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Deep brain stimulation (DBS) involves surgically implanting electrodes within targeted subcortical structures and applying chronic electrical stimulation to produce therapeutic effects. DBS has utility for a range of movement and psychiatric disorders, with DBS of the subthalamic nucleus (STN) for the treatment of Parkinson’s disease a common application. Although DBS can be remarkably effective, several challenges can limit its application and efficacy, including 1) the target neural structures are very small and challenging to accurately implant with electrodes; 2) DBS implantation surgery commonly requires the patient to be awake; 3) selection of beneficial stimulation parameters for chronic therapy is a laborious manual process prone to suboptimal outcomes; 4) chronic therapy is applied constantly regardless of the patient’s present therapeutic needs; and 5) the mechanisms of action of DBS are yet to be fully elucidated. Electrophysiological feedback signals may provide the means for addressing these challenges. A signal localised to the target neural structure could be used like a homing beacon to guide electrode implantation and configuration for chronic therapy. Furthermore, if the signal was measurable under general anaesthesia, it could be used to guide implantation in unconscious patients. A signal that varies with patient symptomatic state and the application of DBS could also guide selection of stimulation parameters, inform on mechanisms of action, and act as a feedback signal for monitoring patient state in real-time and automatically adapting stimulation settings to optimise therapy. This thesis identifies a novel evoked potential – termed evoked resonant neural activity (ERNA) – elicited by DBS pulses applied in the vicinity of the STN and investigates its potential for improving DBS therapy. ERNA is confirmed to be of neural origin and is shown to have largest amplitude in the dorsal subregion of the STN, where DBS for Parkinson’s disease is typical

In recent years, biometrics such as fingerprints and iris scans has been used in authentication. However, conventional biometrics is vulnerable to identity theft, especially in user management systems. As a new biometric without this vulnerability, we focused on brain waves. In this paper, we show that individuals can be authenticated using evoked potentials when they are subjected to ultrasound. We measured the electroencephalograms (EEGs) of 10 experimental ubjects. Individual features were extracted from the power spectra of the EEGs using the principle component analysis and verification was achieved using the support vector machine. We found that for the proposed authentication method, the equal error rate for a single electrode was about 22-32 %. For a multi-electrode, the equal error rate was 4.4 % using the majority decision rule., source:Nakanishi Isao, Maruoka Takehiro. Biometric authentication using evoked potentials stimulated by personal ultrasound. Proceedings of 2019 42nd International Conference on Telecommunications and Signal Processing (TSP), pp. 365-368, Jul. 2019.

Biometrics such as fingerprints and iris scans has been used in authentication. However, conventional biometrics is vulnerable to identity theft, especially in user-management systems. As a new biometrics without this vulnerability, brain waves have been a focus. In this paper, brain waves (electroencephalograms (EEGs)) were measured from ten experiment subjects. Individual features were extracted from the log power spectra of the EEGs using principal component analysis, and verification was achieved using a support vector machine. It was found that, for the proposed authentication method, the equal error rate (EER) for a single electrode was about 22–32%, and that, for a multiple electrodes, was 4.4% by using the majority decision rule. Furthermore, nonlinear features based on chaos analysis were introduced for feature extraction and then extended to multidimensional ones. By fusing the results of all electrodes when using the proposed multidimensional nonlinear features and the spectral feature, an EER of 0% was achieved. As a result, it was confirmed that individuals can be authenticated using induced brain waves when they are subjected to ultrasounds., source:Isao Nakanishi, Takehiro Maruoka. Biometrics Using Electroencephalograms Stimulated by Personal Ultrasound and Multidimensional Nonlinear Features. Electronics. 2020, 9, 24.

Introduction. Aerobic exercise interventions may affect different cognitive domains such as attention, working memory, inhibition, etc. However, the neural mechanisms underlying this relationship, remains uncertain. Objective. To perform a systematic review on exercise intervention studies that use event-related potentials (ERPs) as outcome for cognitive performance. Methods. We identified studies through searches in four databases reporting the effects of either an acute bout or chronic exercise on any ERP associated with cognitive performance. Study population included participants >17 years of age with or without a diagnosis. Results. A total of 5,797 records were initially identified through database searching of which 52 were eligible for inclusion. Most studies were of acute aerobic exercise with moderate intensity. Results were heterogenious across studies, but there was a trend that ERP amplitude increased and (to a lesser extent) latencies decreased post-exercise. The P3 ERP was the most often reported ERP. Conclusion. Heterogeneity across studies regarding methodology limited the possibility to draw definitive conclusions but the most consistent findings were that acute aerobic exercise was associated with higher amplitudes, and to a lesser extent shorter latencies, of ERPs.

Introduction. Aerobic exercise interventions may affect different cognitive domains such as attention, working memory, inhibition, etc. However, the neural mechanisms underlying this relationship, remains uncertain. Objective. To perform a systematic review on exercise intervention studies that use event-related potentials (ERPs) as outcome for cognitive performance. Methods. We identified studies through searches in four databases reporting the effects of either an acute bout or chronic exercise on any ERP associated with cognitive performance. Study population included participants >17 years of age with or without a diagnosis. Results. A total of 5,797 records were initially identified through database searching of which 52 were eligible for inclusion. Most studies were of acute aerobic exercise with moderate intensity. Results were heterogenious across studies, but there was a trend that ERP amplitude increased and (to a lesser extent) latencies decreased post-exercise. The P3 ERP was the most often reported ERP. Conclusion. Heterogeneity across studies regarding methodology limited the possibility to draw definitive conclusions but the most consistent findings were that acute aerobic exercise was associated with higher amplitudes, and to a lesser extent shorter latencies, of ERPs.

This article presents the design and development of a portable prototype for the acquisition, processing and classification of EEG signals with the aim of characterizing visual and auditory stimuli. Two different patients were worked with to validate the results, and the signals were recorded for 4 seconds at a frequency of 500Hz. The patients were exposed to visual and auditory stimuli in different cases, whose frequency of appearance remained constant. For the recording of the signals, a 4-channel acquisition system was designed, which could be configured to work with unipolar or bipolar derivation, as required by the experiment. The selection of the best base in the multi-resolution wavelet analysis, two important parameters were taken into account, the measurement of entropy and the percentages of classification of these levels, because the evoked potentials are generally constant in their morphology, it was made coherent averaging giving as a result the space-time location where this evoked potential appears, Once the characteristics of the treated signal were obtained, they were classified using two different methods of artificial intelligence, neural networks and vector support machines. At this stage, the measurement of the standard deviation of the data was taken into account to ensure that the learning machine was trained correctly. The results obtained reliably demonstrate the general behaviour of the evoked potentials as a result of the stimuli presented. In addition, it was possible to verify the variation of the patient's alpha waves according to his or her state of relaxation or alert in each case, it is advisable to carry out a much more robust filtering system to increase the signal-to-noise ratio of the EEG signal, facilitate its analysis and improve the results., Este artículo presenta el diseño y desarrollo de un prototipo portátil para la adquisición, procesamiento y clasificación de señales EEG con el objetivo de caracterizar estímulos visuales y auditivos, se trabajó con dos pacientes diferentes para la validación de los resultados, se realizó el registro de las señales durante 4 segundos a una frecuencia de 500Hz. Los pacientes fueron expuestos a estímulos visuales y auditivos en diferentes casos, cuya frecuencia de aparición permanecía constante. Para el registro de las señales se diseñó un sistema de adquisición de 4 canales configurables entre sí para trabajar con derivación unipolar o bipolar según requiera el experimento. La selección de la mejor base en el análisis multi-resolución de wavelet se tuvieron en cuenta dos parámetros importantes, la medida de la entropía y los porcentajes de clasificación de dichos niveles, debido a que los potenciales evocados son generalmente constantes en su morfología, se hizo promediación coherente dando como resultado la ubicación espacio-tiempo donde aparece dicho potencial evocado, una vez se obtuvo las características de la señal tratada se procedió a clasificarlas mediante dos métodos diferentes de inteligencia artificial, redes neuronales y máquinas de soporte vectorial, en esta etapa se tomó en cuenta la medida de la desviación estándar de los datos, para garantizar que la máquina de aprendizaje se entrene de manera correcta. Los resultados obtenidos demuestran de manera fidedigna el comportamiento general de los potenciales evocados como resultado a los estímulos presentados, además de que se pudo comprobar la variación de las ondas alfa del paciente según su estado de relajación o alerta en cada caso, es recomendable realizar un sistema de filtrado mucho más robusto para aumentar la relación señal a ruido de la señal EEG, facilitar su análisis y mejorar los resultados.

Biometrics such as fingerprints and iris scans has been used in authentication. However, conventional biometrics is vulnerable to identity theft, especially in user-management systems. As a new biometrics without this vulnerability, brain waves have been a focus. In this paper, brain waves (electroencephalograms (EEGs)) were measured from ten experiment subjects. Individual features were extracted from the log power spectra of the EEGs using principal component analysis, and verification was achieved using a support vector machine. It was found that, for the proposed authentication method, the equal error rate (EER) for a single electrode was about 22–32%, and that, for a multiple electrodes, was 4.4% by using the majority decision rule. Furthermore, nonlinear features based on chaos analysis were introduced for feature extraction and then extended to multidimensional ones. By fusing the results of all electrodes when using the proposed multidimensional nonlinear features and the spectral feature, an EER of 0% was achieved. As a result, it was confirmed that individuals can be authenticated using induced brain waves when they are subjected to ultrasounds.

In recent years, biometrics such as fingerprints and iris scans has been used in authentication. However, conventional biometrics is vulnerable to identity theft, especially in user management systems. As a new biometric without this vulnerability, we focused on brain waves. In this paper, we show that individuals can be authenticated using evoked potentials when they are subjected to ultrasound. We measured the electroencephalograms (EEGs) of 10 experimental ubjects. Individual features were extracted from the power spectra of the EEGs using the principle component analysis and verification was achieved using the support vector machine. We found that for the proposed authentication method, the equal error rate for a single electrode was about 22-32 %. For a multi-electrode, the equal error rate was 4.4 % using the majority decision rule.

Auditory verbal hallucinations (AVH) are common in patients with borderline personality disorder (BPD). We examined two candidate mechanisms of AVH in patients with BPD, suggested to underlie sensory processing systems that contribute to psychotic symptoms in patients with schizophrenia; sensory gating (P50 ratio and P50 difference) and change detection (mismatch negativity; MMN). Via electroencephalographic recordings P50 amplitude, P50 ratio, P50 difference and MMN amplitude were compared between 23 borderline patients with and 25 without AVH, and 26 healthy controls. Borderline patients with AVH had a significantly lower P50 difference compared with healthy controls, whereas no difference was found between borderline patients without AVH and healthy controls. The groups did not differ on MMN amplitude. The impaired sensory gating in patients with borderline personality disorder who experience AVH implies that P50 sensory gating deficiencies may underlie psychotic vulnerability in this specific patient group. Patients with borderline personality disorder with or without AVH did not have problems with auditory change detection. This may explain why they are spared from the poor outcome associated with negative symptoms and symptoms of disorganization in patients with chronic schizophrenia.

Auditory verbal hallucinations (AVH) are common in patients with borderline personality disorder (BPD). We examined two candidate mechanisms of AVH in patients with BPD, suggested to underlie sensory processing systems that contribute to psychotic symptoms in patients with schizophrenia; sensory gating (P50 ratio and P50 difference) and change detection (mismatch negativity; MMN). Via electroencephalographic recordings P50 amplitude, P50 ratio, P50 difference and MMN amplitude were compared between 23 borderline patients with and 25 without AVH, and 26 healthy controls. Borderline patients with AVH had a significantly lower P50 difference compared with healthy controls, whereas no difference was found between borderline patients without AVH and healthy controls. The groups did not differ on MMN amplitude. The impaired sensory gating in patients with borderline personality disorder who experience AVH implies that P50 sensory gating deficiencies may underlie psychotic vulnerability in this specific patient group. Patients with borderline personality disorder with or without AVH did not have problems with auditory change detection. This may explain why they are spared from the poor outcome associated with negative symptoms and symptoms of disorganization in patients with chronic schizophrenia.

It is known that the longer an information has been memorized, the stronger is its memory trace, and that emotionally-valenced information is more solid than neutral one. We investigated whether the emotional content of recent information might enhance its memory, making it as familiar as information known for a long time. We compared ERPs alternately recorded in response to old and solid information from long term memory (i.e., faces of popular movie stars), to recently acquired emotional information (faces of fictional characters), and to completely new information (faces of previously unknown people). Initially participants familiarized with the fictional police dossiers of 10 victims of dramatic deaths (recent faces), twice a day for seven days before EEG recordings. Recent faces were compared with faces of movie stars and unknown faces in an old/new recognition task. N200 and FN400 responses were affected by face familiarity (with no difference between old and recent faces), while parietal late positivity (LP) was sensitive to temporal recency, being it greater to old than recent faces. Interestingly, LP amplitude was similar for old and recent own-sex faces (victims) that were therefore equally memorable. It is shown that emotional memory can overcome temporal recency thus improving memory recall.

The variety of electrophysiological tests currently available allows objective audiograms to be reliably obtained in patients who cannot participate in behavioral (psycho-acoustical) measurements. However, many patients with thresholds within the normal range, report difficulties in understanding speech in noisy environment. One possible cause of such supra-threshold deficit is related to a faulty mode of neural coding, called temporal coding that is in part responsible to convey the full spectro-temporal characteristics of the sound pressure wave into the neural pathways. One electrophysiological measure that could prove itself to be more sensible to probing the neural temporal code is the Frequency-Following Response (FFR). The FFR is a steady-state auditory evoked potential that can be recorded with scalp electrodes following an auditory stimulation. The FFR is a short latency response ($<$10ms), that mimics the spectro-temporal profile of sustained stimuli. Depending on the recording parameters and subjects characteristics, FFR generators can be of pre-neural and neural origin, reflecting different stages of auditory stimuli processing operating from the cochlea to the cortex. In particular, the neural origin of the FFR, reflect the neural phase-locking process and thus offers a means to probe the quality of the neural temporal code representing one of the sensory versions of the stimulus in the auditory pathways.In addition to the sustained components, most stimuli also evoke the transient Auditory Brainstem Response (ABR) triggered by stimulus onset and offset. Complex stimuli evoke FFRs exhibiting phase-locking to both the stimulus Envelope (ENV) and its Temporal Fine Structure (TFS), i.e. to the instantaneous sound pressure variations. The former, also called the envelope-following response (EFR), mainly results from the half-wave rectification process at the inner hair cell synapse and therefore, is usually considered of neural origin. Specifically, for the, Doctorat en Sciences biomédicales et pharmaceutiques (Médecine), info:eu-repo/semantics/nonPublished

We investigated how the brain represents and processes proper and common names by measuring event-related brain potentials (ERPs) while participants performed a lexical decision task. We capitalized on the fact that in Italian proper names require an upper-case initial letter. Stimuli were either in their typical (proper names with upper-case letter and common names with lower-case letter, Teresa, matita ‘pencil’) or atypical/less frequent written format (proper names with lower-case letter and upper-case with upper-case letter, teresa, Matita). Results showed effects on both early and late negativities (N100 and N400) and early and late positivities (P200 and Late Positivity). Interestingly, the positivities showed an interaction between orthographic typicality and name category, while negativities were associated with letter case independently of name category (N100), or with category membership independently of case (N400). Our results indicate that the brain detects the difference between proper and common names early on and tracks this distinction at different points in time during processing.

Exercise-induced hypoalgesia (EIH) refers to an acute reduction in pain that occurs during or following exercise. It is well described in healthy adults, but is more varied in people with chronic pain. In both healthy adults and people with chronic pain, the mechanisms responsible for EIH are not clear. therefore, the aim of this thesis was to enhance understanding of the mechanisms of EIH in healthy adults. Four studies were designed to achieve this. In Chapter 3, somatosensory evoked potential amplitude was unchanged after isometric exercise whereas laser evoked potential amplitude decreased. This suggested a possible role of the peripheral nociceptor in EIH because nociceptor excitation was a primary difference between the electrical and laser stimuli used to elicit somatosensory and laser evoked potentials, respectively. Greater effects of exercise on reduce pressure pain compared to thermal pain were also observed. In Chapter 4, aerobic exercise reduced laser evoked potential amplitudes and again, EIH was greater for pressure compared to thermal stimuli. In Chapter 5, occlusion of blood flow during exercise to a non-exercise limb attenuated EIH in the limb, implying that a factor released into the blood during exercise acts at the periphery to influence EIH. Chapters 3-5 provide evidence for a peripheral mechanisms of EIH that is larger for mechanosensitive compared to thermosensitive nociceptive pathways. However, identification of this peripheral mechanism does not preclude involvement of central and/or cognitive changes in EIH. This was explored in Chapter 6, where it was shown that preceding exercise with education about EIH augmented EIH. This suggests that cognitive processes involved in the appraisal of pain contribute to EIH, and can be manipulated to influence it. Chapter 7 showed, by meta-analysis, that the magnitude of EIH is disrupted in people with fibromyalgia or knee osteoarthritis compared to healthy adults. Overall, this thesis revealed that EI

Epilepsy affects around 50 million people worldwide. Brain injuries and lesions, such as traumatic brain injury, central nervous system infection and stroke, are associated with higher risk of developing epilepsy. It is hypothesised that electrically-induced brain responses (probing responses) can reflect physiological changes during epileptogenesis, which may provide insights into epileptogenesis and possible new therapies. A systematic continuous longitudinal study of probing responses in a well-controlled environment with both normal and epileptic brains is presented. The objective of this study is to demonstrate how electrically-induced neural responses (probing) track the physiological changes in the brain during epileptogenesis. Intrahippocampal tetanus toxin rat models were used as the model of epilepsy. Control rats received injections without tetanus toxin. Epidural electrodes were implanted to deliver electrical stimulation and record EEG over periods of 9 to 10 weeks in a room with controlled temperature and automatic dark/light switching. It is demonstrated that probing responses can expose sleep/wake cycles, recovery from surgery and epileptogenesis over the study period. The differences between probing responses in sleep and wake states are quantified by a two-level mixed-effects linear regression model. The changes of probing responses related to the recovery from surgery are modelled by a modified logistic function. The probing responses related to epileptogenesis in tetanus toxin models are uncovered after the effects of surgical recovery and sleep/wake cycle are removed. The changes can be observed in the infradian time scale and several markers are found that are associated with the time of the peak of seizure occurrence and the time of seizure remission. This study is the first step to identify stages of epileptogenesis using probing responses. The potential clinical application of probing can be a biomarker for epileptogenesis, a prognostic tool

Increasing context heterogeneity has been found to reduce attention deployment towards an embedded target item. Heterogeneity in visual search tasks is typically induced by segmenting the background into several perceptual groups. In the present study, however, context heterogeneity was induced by varying whole-field heterogeneity, i.e., the degree of distractor variability within the entire context. This allowed us to (i) more gradually vary context heterogeneity, and (ii) investigate attention deployment on a whole-field scale. Results showed that both search performance and amplitude of the N2pc (lateralized ERP; posterior contralateral negativity in the N2 range) monotonically decreased with increasing context heterogeneity, which confirmed that there was less efficient attention deployment for more heterogeneous contexts. The amplitude of the bilateral N2 exhibited a U-shaped function, suggesting global perception for the lowest and highest levels of heterogeneity, but local processing for intermediate heterogeneity levels. Independent component analyses revealed an occipital ERP-contributing effective source cluster that may reflect stimulus representations on a saliency map. With increasing heterogeneity, these sources exhibited more theta band activity for distractors and less theta band activity for targets. Alpha band activity of a second component cluster varied with heterogeneity level, and low-theta/delta activity of a third source cluster distinguished target presence versus absence. In sum, our results suggest that independent brain sources contributed to the differential processing of heterogeneous versus homogeneous contexts

In recent years, several studies have reported a relatively high frequency of polyneuropathy in patients with Parkinson’s disease (PD), in particular, in patients receiving levodopa-carbidopa intestinal gel (LCIG) infusion. In spite of the several patients investigated with nerve conduction studies, no study has prospectively explored a possible central nervous system involvement of patients receiving LCIG infusion. We prospectively evaluated eight PD patients receiving LCIG infusion, who underwent neurophysiological evaluations with nerve conduction studies, visual, somatosensory and motor evoked potentials before LCIG infusion, and 1 and 6 months after. At 6 months follow-up, we found significant reduction in sural nerve SNAP amplitude, increase of central sensory conduction time N22-P40, and increases of central motor conduction time recorded from I dorsal interosseous and tibialis anterior. In PD patients with LCIG infusion, we found a subclinical neurophysiological impairment of both peripheral and central nervous system.

Inhibitory control refers to the ability to inhibit an action once it has been initiated. Impaired inhibitory control plays a key role in triggering relapse in some pathological states, such as addictions. Therefore, a major challenge of current research is to establish new methods to strengthen inhibitory control in these "high-risk" populations. In this attempt, the right inferior frontal cortex (rIFC), a neural correlate crucial for inhibitory control, was modulated using transcranial direct current stimulation (tDCS). Healthy participants (n = 31) were presented with a "Go/No-go" task, a well-known paradigm to measure inhibitory control. During this task, an event-related potential (ERP) recording (T1; 32 channels) was performed. One subgroup (n = 15) was randomly assigned to a condition with tDCS (anodal electrode was placed on the rIFC and the cathodal on the neck); and the other group (n = 16) to a condition with sham (placebo) tDCS. After one 20- minute neuromodulation session, all participants were confronted again with the same ERP Go/No-go task (T2). To ensure that potential tDCS effects were specific to inhibition, ERPs to a face-detection task were also recorded at T1 and T2 in both subgroups. The rate of commission errors on the Go/No-go task was similar between T1 and T2 in both neuromodulation groups. However, the amplitude of the P3d component, indexing the inhibition function per se, was reduced at T2 as compared with T1. This effect was specific for participants in the tDCS (and not sham) condition for correctly inhibited trials. No difference in the P3 component was observable between both subgroups at T1 and T2 for the face detection task. Overall, the present data indicate that boosting the rIFC specifically enhances inhibitory skills by decreasing the neural activity needed to correctly inhibit a response., SCOPUS: ar.j, info:eu-repo/semantics/published

Purpose: The present study examined dynamic changes in neural activity of the anterior cingulate cortex (ACC) and the midbrain periaqueductal gray (PAG) during the micturition reflex in a Parkinson's disease (PD) model as well as the effects of direct stimulation of the ACC on the micturition reflex. Materials and Methods: Electrodes were inserted into the ACC or the PAG, and the effects of intravenous (i.v.) administration of ZM24138 (ZM: adenosine A2A receptor antagonist) on the pelvic nerve evoked field potentials were examined. The effect of electrical stimulation of the ACC was also examined. Results: PD rats showed bladder overactivity evidenced by a significant decrease in intercontraction intervals (ICI) compared with sham rats. I.v. administration of ZM increased ICI in both groups with the inhibitory effects being greater in PD; and dose-dependently increased the amplitude of evoked potentials in the ACC of PD rats but not in sham rats. I.v. administration of ZM reduced the evoked potential amplitude in the PAG of both groups with the inhibitory effects being greater in PD vs. sham rats. Electrical stimulation of the ACC significantly increased ICI. Conclusions: These results suggest that ACC neurons have an inhibitory role in bladder control because neural activity in the ACC was significantly increased along with suppression of bladder overactivity after ZM administration in the PD model, and the stimulation of the ACC inhibited the micturition reflex. Understanding the roles of the ACC in the modulation of micturition could provide further insights into the pathophysiology of OAB.

Purpose: The present study examined dynamic changes in neural activity of the anterior cingulate cortex (ACC) and the midbrain periaqueductal gray (PAG) during the micturition reflex in a Parkinson's disease (PD) model as well as the effects of direct stimulation of the ACC on the micturition reflex. Materials and Methods: Electrodes were inserted into the ACC or the PAG, and the effects of intravenous (i.v.) administration of ZM24138 (ZM: adenosine A2A receptor antagonist) on the pelvic nerve evoked field potentials were examined. The effect of electrical stimulation of the ACC was also examined. Results: PD rats showed bladder overactivity evidenced by a significant decrease in intercontraction intervals (ICI) compared with sham rats. I.v. administration of ZM increased ICI in both groups with the inhibitory effects being greater in PD; and dose-dependently increased the amplitude of evoked potentials in the ACC of PD rats but not in sham rats. I.v. administration of ZM reduced the evoked potential amplitude in the PAG of both groups with the inhibitory effects being greater in PD vs. sham rats. Electrical stimulation of the ACC significantly increased ICI. Conclusions: These results suggest that ACC neurons have an inhibitory role in bladder control because neural activity in the ACC was significantly increased along with suppression of bladder overactivity after ZM administration in the PD model, and the stimulation of the ACC inhibited the micturition reflex. Understanding the roles of the ACC in the modulation of micturition could provide further insights into the pathophysiology of OAB.

Purpose: The present study examined dynamic changes in neural activity of the anterior cingulate cortex (ACC) and the midbrain periaqueductal gray (PAG) during the micturition reflex in a Parkinson's disease (PD) model as well as the effects of direct stimulation of the ACC on the micturition reflex. Materials and Methods: Electrodes were inserted into the ACC or the PAG, and the effects of intravenous (i.v.) administration of ZM24138 (ZM: adenosine A2A receptor antagonist) on the pelvic nerve evoked field potentials were examined. The effect of electrical stimulation of the ACC was also examined. Results: PD rats showed bladder overactivity evidenced by a significant decrease in intercontraction intervals (ICI) compared with sham rats. I.v. administration of ZM increased ICI in both groups with the inhibitory effects being greater in PD; and dose-dependently increased the amplitude of evoked potentials in the ACC of PD rats but not in sham rats. I.v. administration of ZM reduced the evoked potential amplitude in the PAG of both groups with the inhibitory effects being greater in PD vs. sham rats. Electrical stimulation of the ACC significantly increased ICI. Conclusions: These results suggest that ACC neurons have an inhibitory role in bladder control because neural activity in the ACC was significantly increased along with suppression of bladder overactivity after ZM administration in the PD model, and the stimulation of the ACC inhibited the micturition reflex. Understanding the roles of the ACC in the modulation of micturition could provide further insights into the pathophysiology of OAB.

The brain activity, considered in its hemodynamic (optical imaging: functional Near-Infrared Spectroscopy, fNIRS) and electrophysiological components (event-related potentials, ERPs, N200) was monitored when subjects observed (visual stimulation, V) or observed and heard (visual + auditory stimulation, VU) situations which represented inter-species (human-animal) interactions, with an emotional positive (cooperative) or negative (uncooperative) content. In addition, the cortical lateralization effect (more left or right dorsolateral prefrontal cortex, DLPFC) was explored. Both ERP and fNIRS showed significant effects due to emotional interactions which were discussed at light of cross-modal integration effects. The significance of inter-species effect for the emotional behavior was considered. In addition, hemodynamic and EEG consonant results and their value as integrated measures were discussed at light of valence effect.

Purpose: The present study examined dynamic changes in neural activity of the anterior cingulate cortex (ACC) and the midbrain periaqueductal gray (PAG) during the micturition reflex in a Parkinson's disease (PD) model as well as the effects of direct stimulation of the ACC on the micturition reflex. Materials and Methods: Electrodes were inserted into the ACC or the PAG, and the effects of intravenous (i.v.) administration of ZM24138 (ZM: adenosine A2A receptor antagonist) on the pelvic nerve evoked field potentials were examined. The effect of electrical stimulation of the ACC was also examined. Results: PD rats showed bladder overactivity evidenced by a significant decrease in intercontraction intervals (ICI) compared with sham rats. I.v. administration of ZM increased ICI in both groups with the inhibitory effects being greater in PD; and dose-dependently increased the amplitude of evoked potentials in the ACC of PD rats but not in sham rats. I.v. administration of ZM reduced the evoked potential amplitude in the PAG of both groups with the inhibitory effects being greater in PD vs. sham rats. Electrical stimulation of the ACC significantly increased ICI. Conclusions: These results suggest that ACC neurons have an inhibitory role in bladder control because neural activity in the ACC was significantly increased along with suppression of bladder overactivity after ZM administration in the PD model, and the stimulation of the ACC inhibited the micturition reflex. Understanding the roles of the ACC in the modulation of micturition could provide further insights into the pathophysiology of OAB.

The brain activity, considered in its hemodynamic (optical imaging: functional Near-Infrared Spectroscopy, fNIRS) and electrophysiological components (event-related potentials, ERPs, N200) was monitored when subjects observed (visual stimulation, V) or observed and heard (visual + auditory stimulation, VU) situations which represented inter-species (human-animal) interactions, with an emotional positive (cooperative) or negative (uncooperative) content. In addition, the cortical lateralization effect (more left or right dorsolateral prefrontal cortex, DLPFC) was explored. Both ERP and fNIRS showed significant effects due to emotional interactions which were discussed at light of cross-modal integration effects. The significance of inter-species effect for the emotional behavior was considered. In addition, hemodynamic and EEG consonant results and their value as integrated measures were discussed at light of valence effect.

Ultrasound waves are mechanical undulations above the threshold for human hearing, and have been used widely in both the human body and brain for diagnostic and therapeutic purposes. Ultrasound can be controlled using specially designed transducers into a focus of a few millimeters in diameter. Low intensity ultrasound, such as used in imaging applications, appears to be safe in adults. It is also known that ultrasound waves can penetrate through the skull and be focused within the brain for ablation purposes, employing the heat generation properties of high intensity focused ultrasound. High intensity focused ultrasound is thus used to irreversibly ablate brain tissue in localized areas without observable damage to intermediate tissue and vasculature. Ablation with high intensity focused ultrasound guided by magnetic resonance imaging is used for abolishing brain tumors, and experimentally for pain. Low intensity ultrasound can be utilized beyond imaging in neuroscience and neurology by focusing the ultrasound beam to investigate the structure and function of discrete brain circuits. In contrast to high intensity focused ultrasound, the effects of low intensity focused ultrasound on neurons are reversible. Considering the volume of work on high intensity focused ultrasound, low intensity focused ultrasound remains decidedly underdeveloped. Given the great potential for impact of low intensity focused ultrasound in both clinical and scientific neuromodulation applications, we sought to advance the use of low intensity focused ultrasound for noninvasive, transcranial neuromodulation of human cortex. This dissertation contains novel research on the use of low intensity transcranial focused ultrasound for noninvasive neuromodulation of human cortex. The importance of mechanical forces in the nervous system is highlighted throughout to expand beyond the stigma that nervous function is governed chiefly by electrical and chemical means. Methods of transcranial focused ult

Much of our understanding of the neuronal mechanisms of spatial navigation is derived from chronic recordings in rodents in which head-direction, place, and grid cells have all been described. However, despite the proposed importance of self-reference information to these internal representations of space, their congruence with vestibular signaling remains unclear. Here we have undertaken brain-wide functional mapping using both fMRI and electrophysiological methods to directly determine the spatial extent, strength, and time course of vestibular signaling across the rat forebrain. We find distributed activity throughout thalamic, limbic, and particularly primary sensory cortical areas in addition to known head-direction pathways. We also observe activation of frontal regions, including infralimbic and cingulate cortices, indicating integration of vestibular information throughout functionally diverse cortical regions. These whole-brain activity maps therefore suggest a widespread contribution of vestibular signaling to a self-centered framework for multimodal sensorimotor integration in support of movement planning, execution, spatial navigation, and autonomic responses to gravito-inertial changes.

This study aimed to characterize neuropsychological and linguistic skills in children with Developmental Dyslexia (DD) with and without Language Impairment (LI). Behavioral tests of short-term memory, phonemic awareness, and morphosyntactic processing and electrophysiological responses to agreement violations were administered to 32 DD children (16 with additional LI) and 16 controls. Behavioral data revealed quantitative differences among groups: DD+LI children showed the worst performance, followed by DD-only children and controls. Event-related potential results confirmed atypical morphosyntactic processing in the DD-only group, highlighting qualitative differences between groups. These results support multifactor models of learning disabilities, where different patterns of deficits characterize different subgroups. © 2015

Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis.

The body of work presented is comprised of an analysis of three electronic devices developed for different purposes within the area of brain-computer interface research. The goal of these devices was to optimize effectiveness at as low of a cost as possible. Readily available components were chosen for their cost and abilities relative to similar devices used by other institutions that may require significant funding to achieve. The devices are presented in the order they were developed and represent an increase in complexity. The first was a device for measurement of motion, a simple task requiring only a single component. Secondly, a device to provide a stimulus to aid in treatment of neuropathy of the lower leg is reviewed. This device used a combination of a previously FDA approved stimulation system and electronic components used by hobbyists. Finally, a prototype for a novel device to be used for diagnosis of brain lesions is described, one which combines the scientific protocols used for brain lesion diagnosis and easy to use components into a single comprehensive piece of equipment.

The body of work presented is comprised of an analysis of three electronic devices developed for different purposes within the area of brain-computer interface research. The goal of these devices was to optimize effectiveness at as low of a cost as possible. Readily available components were chosen for their cost and abilities relative to similar devices used by other institutions that may require significant funding to achieve. The devices are presented in the order they were developed and represent an increase in complexity. The first was a device for measurement of motion, a simple task requiring only a single component. Secondly, a device to provide a stimulus to aid in treatment of neuropathy of the lower leg is reviewed. This device used a combination of a previously FDA approved stimulation system and electronic components used by hobbyists. Finally, a prototype for a novel device to be used for diagnosis of brain lesions is described, one which combines the scientific protocols used for brain lesion diagnosis and easy to use components into a single comprehensive piece of equipment.

Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Biosignal Interpretation: Advanced Methods for Neural Signals and Images“. Objectives: An efficient way to investigate the neural basis of nociceptive responses is the analysis of the event-related brain potentials (ERPs). The main objective of this work was to study how adaptation and fatigue affect the ERPs to stimuli of different modalities, by characterizing the responses to infrequent and frequent stimulation in different recording periods. Methods: In this work, series of averaged EEG epochs recorded after thermal, electrical and auditory stimulation were analyzed with time-frequency representation and non-linear measures as spectral entropy and auto-mutual information function. The study was performed by considering the traditional EEG frequency bands. Results: The defined measures presented a statistical significance p-value < 0.01 and accuracy higher than 60% by differentiating windows of response to infrequent (I) and frequent (F) stimuli between the start and end of the EEG recording. Conclusions: These measures permitted to observe some aspects of the subject’s adaptation and the nociceptive response, Peer Reviewed, Postprint (published version)

Compound words in Romance languages may have the head either in the initial or in the final position. In the present event-related potential (ERP) study, we address the hypothesis that Italian compounds are processed differently according to their head position and that this is mostly due to the perceived change in the canonical order of syntactic elements. Compound stimuli (head-initial, head-final, or exocentric) were visually displayed in two presentation modes, as whole words or separated into their constituents, in the context of a lexical decision task. Behavioural results showed an increased split cost in head-final and exocentric compounds as compared to head-initial compounds. ERP results showed an enhanced left anterior negativity (LAN) for head-final and exocentric compounds as compared to head-initial compounds, regardless of the presentation mode. Results suggest that the analogy with syntactic order may influence the internal structure of a compound and, as a consequence, its processing, but other characteristics (such as the grammatical properties of constituents) may affect the processing itself. © 2013 Taylor & Francis.

To determine the optimal use and indications of electroencephalography (EEG) in critical care management of acute brain injury (ABI). An electronic literature search was conducted for articles in English describing electrophysiological monitoring in ABI from January 1990 to August 2013. A total of 165 studies were included. EEG is a useful monitor for seizure and ischemia detection. There is a well-described role for EEG in convulsive status epilepticus and cardiac arrest (CA). Data suggest EEG should be considered in all patients with ABI and unexplained and persistent altered consciousness and in comatose intensive care unit (ICU) patients without an acute primary brain condition who have an unexplained impairment of mental status. There remain uncertainties about certain technical details, e.g. the minimum duration of EEG studies, the montage, and electrodes. Data obtained from both EEG and EP studies may help estimate prognosis in ABI patients, particularly following CA and traumatic brain injury. Data supporting these recommendations is sparse, and high quality studies are needed. EEG is used to monitor and detect seizures and ischemia in ICU patients and indications for EEG are clear for certain disease states, however, uncertainty remains on other applications., SCOPUS: ar.j, info:eu-repo/semantics/published

Metoda merenja i analize električnih potencijala snimljenih površinskim elektrodama sa skeletnih mišića naziva se elektromiografija. Primenom ove metode omogućeno je praćenje mišićne i nervne aktivnosti, a samim tim omogućena je i direktna ocena motornog i indirektna ocena senzornog sistema. Cilj istraživanja je usavršavanje tehnologije merenja i analize elektromiografskih signala koje bi omogućile razvoj novih modela u senzorno-motornom sistemu čoveka. Novorazvijeni sistem, koji je prikazan u ovoj disertaciji, ima dve osnovne namene: podrška bazičnim istraživanjima u domenu neuronauka i podrška kliničkom radu. Prikazana je efikasnost sistema u oceni senzorno-motornog statusa kod pacijenata koji su preživeli moždani udar. Kroz 2 prilaza u merenju i analizi elektromiografskih signala prikazano je kako se može oceniti status senzorno-motornog sistema kod zdravih i kod pacijenata. Prvi prikaz se sastoji u proučavanju spontane mišićne aktivnosti tokom kontrolisanog voljnog pokreta članka i tokom hoda. Ovaj prikaz je iskorišćen za proučavanje kratkoročnih i dugoročnih efekata terapije na senzorno-motorni oporavak pacijenata. Drugi prikaz se sastoji iz proučavanja evociranih motornih potencijala. Na primeru zdravih ispitanika pokazano je kako se na pouzdan i ponovljiv način može iskoristiti projektovana instrumentacija za ocenu senzornomotornog sistema. U analizi mišićnih signala predstavljene su dve nove metode proučavanja spontanih i evociranih potencijala mišića. Za potrebe ocene spontane mišićne aktivnosti uvedene su nove mere kokontrakcije koje omogućavaju ocenu mišićnih aktivacija i koje omogućavaju istovremenu ocenu vremenskih i amplitudskih osobina signala. U oceni evociranih potencijala uvedeni su novi algoritmi za automatsko upravljanje električnom stimulacijom i akvizicijom signala, kao i novi vid vizuelizacije i ocene prostorne raspodela evociranih potencijala. Klinička primena projektovanog mernog sistema i V procedura merenja i analize elektromiografskih sig, Electromyography is a method for measurement and analysis of electrical potentials of muscles in human. Nervous and muscular systems in humans can be assessed by the means of electromyography. This assessment enables direct evaluation of motor status, and indirect evaluation of sensory status. The aim of this research is the development of new technologies for measurement and analysis of electromyography signals, which would enable design of new sensory-motor models. The novel system, presented in this dissertation, has two main purposes: to improve research methodology in basic neurosciences and to support clinical practice. The functioning of the system is presented for the assessment of sensory-motor recovery in stroke patients. Two main approaches are used in measurement and analysis of electromyography signals in healthy subjects and in patients. The first approach consists of studying voluntary contractions by the means of electromyography during ankle movement and during gait. This approach is used for the studying long-term and short-term therapy effects on sensory-motor system during rehabilitation process in stroke patients. The second approach enables measurement and analysis of evoked motor potentials. Reliability and reproducibility of a designed instrumentation for assessment of motor status by studying evoked motor potentials is presented in healthy subjects. Two new methods for the analysis of voluntary muscle contraction and evoked potentilas are presented. For studying voluntary muscle contraction, the cocontraction measurement was introduced. These parameters reflected amplitude and temporal characteristics of recorded signals. For the analysis of evoked motor potentials new algoritms for the control of electrical stimulation and acquisition are presented. The novel method for vizualisation and assessment of spatial distribution of evoked potential is designed for the purposes of sensory-motor assessment. Clinical applications of the designed inst

Thirty-six blast-exposed patients and twenty-nine non-blast-exposed control subjects were tested on a battery of behavioral and electrophysiological tests that have been shown to be sensitive to central auditory processing deficits. Abnormal performance among the blast-exposed patients was assessed with reference to normative values established as the mean performance on each test by the control subjects plus or minus two standard deviations. Blast-exposed patients performed abnormally at rates significantly above that which would occur by chance on three of the behavioral tests of central auditory processing: the Gaps-In-Noise, Masking Level Difference, and Staggered Spondaic Words tests. The proportion of blast-exposed patients performing abnormally on a speech-in-noise test (Quick Speech-In-Noise) was also significantly above that expected by chance. These results suggest that, for some patients, blast exposure may lead to difficulties with hearing in complex auditory environments, even when peripheral hearing sensitivity is near normal limits., Published in the Journal of Rehabilitation Research & Development, v49 n7 p1005-1024, 2012. The original document contains color images.

Kmenové sluchové evokované potenciály (Brainstem Auditory Evoked Potentials) jsou odpovědi na podráždění vláskových buněk vnitřního ucha zdrojem stimulu. Podnětem podráždění je v případě evokovaných potenciálů zvuk. Ten se transformuje na elektrický potenciál, jehož vznik je metodou BERA (BAEP) zaznamenáván v místě od sluchového nervu až do kmene mozkového. Jedná se tedy o evokované potenciály s krátkou latencí (Short Latency Responses - SLR), vyskytují se mezi 0 - 10 ms po stimulaci. Odpovědi vyvolané stimuly jsou detekovány pomocí elektrod umístěných na povrchu lebky. Napěťová úroveň vzniklého evokovaného potenciálu je velice malá, proto je zapotřebí tento signál zesilovat a průměrovat pomocí počítačové techniky, aby bylo možné dosáhnout hodnotitelných výsledků. Tato práce je zaměřena na popis těchto potenciálů a návod k jejich vyšetření metodou BERA., Brainstem auditory evoked potentials are responses to irritations of the inner ear hair cells by the source of stimuli. In case of evoked potentials, a sound is an impulse of irritation. It is transformed into an electrical potential and its formation is recorded by the BERA method from auditory nerve to brainstem. They are evoked potentials with short latency (Short Latency Responses - SLR) and occur between 0 - 10 ms after stimulation. Responses induced by stimuli are detected by electrodes placed on the surface of the skull. Voltage level of generated evoked potential is very small, therefore it is necessary to amplify and average the signal using computer techniques to achieve evaluable results. This bachelor thesis is focused on the description of these potentials and instructions for their examination by BERA., Ve zpracování, Import 03/08/2012

Každé podráždění smyslových orgánů má za následek odpověď, která se šíří nervovými drahami do mozku, kde dochází ke zpracování. Pomocí neinvazivního vyšetření evokovanými potenciály zkoumáme funkčnost nervového systému za pomoci stimulu. Vyšetření se využívá při předpokladu poruchy sluchových, zrakových či somatosenzorických nervových drah. Nalezení poškozené oblasti či příčiny poruchy lékařům napomáhá k určení diagnózy a následné léčbě. V mé práci se zabývám evokovanými potenciály, které nám dávají souhrnné stejnostranné odezvy na intenzivní zvuk. Jedná se o vestibulární evokované myogenní potenciály. Test nám udává, zda přední vestibulární nerv, kulovitý váček a vestibulární nervové cesty pracují správně. V bakalářské práci se zaměřuji na správné nalezení a nastavení technických parametrů pro metodu měření vestibulárních evokovaných myogenních potenciálů a práci s přístrojem ICS Chartr EP 200., Each sensory irritation results in a response which is spread by nerve pathways to the brain where it is processed. By using non-invasive examination of evocated potentials, we try to explore the functionality of the nervous system with the help of stimulus. The examination is used when we assume malfunction of hearing, visual or somatosensory nerve pathways. Finding any damaged area or cause of damage helps doctors determine the diagnosis and subsequent treatment. In my work I deal with evocated potentials which give us summary ipsilateral responses to intensive sound. The evocated potentials are vestibular evocated myogenic potentials. The test tells us if the anterior vestibular nerve, saccule and vestibular nerve pathways work correctly. My Bachelor's thesis is focused on the right finding and setting of technical parameters for a measurement of vestibular evocated myogenic potentials, and my work with the device ICS Chartr EP 200., Ve zpracování, Import 03/08/2012

Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder characterized by myokymia and attacks of ataxic gait often precipitated by stress. Several genetic mutations have been identified in the Shaker-like K+ channel Kv1.1 (KCNA1) of EA1 individuals, including V408A, which result in remarkable channel dysfunction. By inserting the heterozygous V408A, mutation in one Kv1.1 allele, a mouse model of EA1 has been generated (Kv1.1V408A/+). Here, we investigated the neuromuscular transmission of Kv1.1V408A/+ ataxic mice and their susceptibility to physiologically relevant stressors. By using in vivo preparations of lateral gastrocnemius (LG) nerve-muscle from Kv1.1+/+ and Kv1.1V408A/+ mice, we show that the mutant animals exhibit spontaneous myokymic discharges consisting of repeated singlets, duplets or multiplets, despite motor nerve axotomy. Two-photon laser scanning microscopy from the motor nerve, ex vivo, revealed spontaneous Ca2+ signals that occurred abnormally only in preparations dissected from Kv1.1V408A/+ mice. Spontaneous bursting activity, as well as that evoked by sciatic nerve stimulation, was exacerbated by muscle fatigue, ischemia and low temperatures. These stressors also increased the amplitude of compound muscle action potential. Such abnormal neuromuscular transmission did not alter fiber type composition, neuromuscular junction and vascularization of LG muscle, analyzed by light and electron microscopy. Taken together these findings provide direct evidence that identifies the motor nerve as an important generator of myokymic activity, that dysfunction of Kv1.1 channels alters Ca2+ homeostasis in motor axons, and also strongly suggest that muscle fatigue contributes more than PNS fatigue to exacerbate the myokymia/neuromyotonia phenotype. More broadly, this study points out that juxtaparanodal K+ channels composed of Kv1.1 subunits exert an important role in dampening the excitability of motor nerve axons during fatigue or ischemic

This study investigated the temporal dynamics of emotional and cognitive processing underlying decision-making in moral judgment. Thirty-seven participants were presented with a set of 60 dilemmas varying in whether killing one individual was an intended means to save others (instrumental dilemmas) or a foreseen but unintended consequence (incidental dilemmas). Participants were required to decide between Options A (letting a specific number of people die) and B (killing one person to save a specific number of people). ERPs were recorded to a slide displaying the letters A and B while subjects were deciding between the options, and movement-related potentials were recorded time-locked to the behavioral response, thus allowing the investigation of both stimulus- and response-related processes during decision-making. Ratings of emotional valence and arousal experienced during decision-making were collected after each decision. Compared with incidental dilemmas, instrumental dilemmas prompted a lower number of B choices and significantly more unpleasant decisions. A larger P260 component was found in the frontopolar and frontal areas when subjects were deciding on instrumental than incidental dilemmas, possibly reflecting an immediate affective reaction during the early stage of assessment and formation of preferences between available options. On the other hand, decisions on incidental dilemmas required greater attentional resources during the fairly controlled later processing, as reflected in the larger slow wave amplitudes. In addition, facilitation of action selection and implementation was found for incidental dilemmas during the second stage of decision-making, as supported by the larger amplitudes of both components of the Bereitschaftspotential. © 2012 Massachusetts Institute of Technology.

Background. A visual prosthesis is a conceptual device designed to activate residual functional neurons in the visual pathway of blind individuals to produce artificial vision. Such device, when applied to stimulate the vitreous surface of the retina, has proven feasible in producing patterned light perception in blind individuals suffering from dystrophic diseases of the retina, such as aged-related macular degeneration (AMD). However the practicality of such approach has been challenged by the difficulty of surgical access and the risks of damaging the neuroretina. Positioning a visual implant over the scleral surface of the eye could present a safer alternative but this stimulation modality has not been tested in diseased retinas. Additionally, recent research has shown that the adult neocortex retains substantial plasticity following a disruption to its visual input and the potential deterioration in visual capabilities as a result of such experience modification may undermine the overall bionic rescue strategy.Methods. Two animal models mimicking the principal pathologies found in AMD, namely photoreceptor degeneration and reduced retinal ganglion cell mass, were used to evaluate the efficacy of trans-scleral stimulation of the retina by recording electrical evoked potentials in the visual cortex. The visual performance following the loss of pattern vision induced by bilateral eyelid suturing in adult mice was examined by analysing visual evoked potentials.Findings. Spatially differentiated cortical activations were obtained notwithstanding the underlying retinopathy in the experiment animals. The charge density thresholds were found to be similar to controls and below the bioelectric safety limit. After prolonged visual deprivation (weeks) in the mouse, the visual cortical responses evoked by either electrical or photic stimuli were both significantly reduced. An assessment of different visual capabilities using patterned stimuli demonstrated that whilst visua

Evoked potential modulation allows the study of dynamic brain processing. The mechanism of movement gating of the frontal N30 component of somatosensory evoked potentials (SEP) produced by the stimulation of the median nerve at wrist remains to be elucidated. At rest, a power enhancement and a significant phase-locking of the electroencephalographic (EEG) oscillation in the beta/gamma range (25-35 Hz) are related to the emergence of the N30. The latter was also perfectly identified in presence of pure phase-locking situation. Here, we investigated the contribution of these rhythmic activities to the specific gating of the N30 component during movement. We demonstrated that concomitant execution of finger movement of the stimulated hand impinges such temporal concentration of the ongoing beta/gamma EEG oscillations and abolishes the N30 component throughout their large topographical extent on the scalp. This also proves that the phase-locking phenomenon is one of the main actors for the N30 generation. These findings could be explained by the involvement of neuronal populations of the sensorimotor cortex and other related areas, which are unable to respond to the phasic sensory activation and to phase-lock their firing discharges to the external sensory input during the movement. This new insight into the contribution of phase-locked oscillation in the emergence of the N30 and in its gating behavior calls for a reappraisal of fundamental and clinical interpretation of the frontal N30 component., Journal Article, Research Support, Non-U.S. Gov't, FLWIN, info:eu-repo/semantics/published

Evoked potential modulation allows the study of dynamic brain processing. The mechanism of movement gating of the frontal N30 component of somatosensory evoked potentials (SEP) produced by the stimulation of the median nerve at wrist remains to be elucidated. At rest, a power enhancement and a significant phase-locking of the electroencephalographic (EEG) oscillation in the beta/gamma range (25-35 Hz) are related to the emergence of the N30. The latter was also perfectly identified in presence of pure phase-locking situation. Here, we investigated the contribution of these rhythmic activities to the specific gating of the N30 component during movement. We demonstrated that concomitant execution of finger movement of the stimulated hand impinges such temporal concentration of the ongoing beta/gamma EEG oscillations and abolishes the N30 component throughout their large topographical extent on the scalp. This also proves that the phase-locking phenomenon is one of the main actors for the N30 generation. These findings could be explained by the involvement of neuronal populations of the sensorimotor cortex and other related areas, which are unable to respond to the phasic sensory activation and to phase-lock their firing discharges to the external sensory input during the movement. This new insight into the contribution of phase-locked oscillation in the emergence of the N30 and in its gating behavior calls for a reappraisal of fundamental and clinical interpretation of the frontal N30 component., Journal Article, Research Support, Non-U.S. Gov't, FLWIN, info:eu-repo/semantics/published

While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2–22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

It is mandatory to explore the new diagnostic tools in order to gain a new insight into a variety of gastrointestinal pathologies in the field of pediatric surgery. For that purpose, we applied the technique of somatosensory evoked potential to analyze the afferent nervous system from the anal canal. Magnetic spinal stimulation technique was also used in children to examine the efferent pathway from the sacrum to the external anal sphincter. These studied revealed some important findings in the understanding of pathophysiology of chronic constipation and anorectal malformations. Further application of recent sophisticated modalities such as repetitive magnetic stimulation or PET will be promising for future investigation.

ObjectiveTo examine the affects of aging on auditory cortical activity during a short-term memory task.MethodsYoung and elderly subjects performed a working memory task using acoustically presented digits while evoked potential components (N100, P200) generated by auditory cortex were recorded. Reaction time and N100/P200 amplitudes and latency were analyzed as a function of memory load.ResultsN100 amplitude to probes decreased as a function of memory load in young subjects, but increased as a function of memory load in the elderly. Young subjects also exhibited changes in N100 latency during memorization of list items, a result not found in elderly subjects.ConclusionsWe conclude that normal aging is associated with a qualitatively different pattern of N100 responses during memory retrieval, and a static N100 response during encoding. The findings suggest that aging is accompanied by functional reorganization of the neural network that supports retrieval in auditory working memory.

ObjectiveTo examine the affects of aging on auditory cortical activity during a short-term memory task.MethodsYoung and elderly subjects performed a working memory task using acoustically presented digits while evoked potential components (N100, P200) generated by auditory cortex were recorded. Reaction time and N100/P200 amplitudes and latency were analyzed as a function of memory load.ResultsN100 amplitude to probes decreased as a function of memory load in young subjects, but increased as a function of memory load in the elderly. Young subjects also exhibited changes in N100 latency during memorization of list items, a result not found in elderly subjects.ConclusionsWe conclude that normal aging is associated with a qualitatively different pattern of N100 responses during memory retrieval, and a static N100 response during encoding. The findings suggest that aging is accompanied by functional reorganization of the neural network that supports retrieval in auditory working memory.

Agrin controls the formation of the neuromuscular junction. Whether it regulates the differentiation of other types of synapses remains unclear. Therefore, we have studied the role of agrin in cultured hippocampal neurons. Synaptogenesis was severely compromised when agrin expression or function was suppressed by antisense oligonucleotides and specific antibodies. The effects of antisense oligonucleotides were found to be highly specific because they were reversed by adding recombinant agrin and could not be detected in cultures from agrin-deficient animals. Interestingly, the few synapses formed in reduced agrin conditions displayed diminished vesicular turnover, despite a normal appearance at the EM level. Thus, our results demonstrate the necessity of agrin for synaptogenesis in hippocampal neurons.

Objectives - To assess the diagnostic value of electrophysiological tests in patients with sciatica. Materials and methods - The diagnostic value of electrophysiological tests were evaluated in 25 patients with mono- radicular sciatica. The electrophysiological study included dermatomal somatosensory evoked potentials, electromyography, F-wave latencies, H- reflexes and motor and sensory nerve conduction determinations. The results of the electrophysiological examinations were evaluated blindly, and the test results were analysed separately by a receiver operating characteristic (ROC) analysis. Furthermore, the 5 modalities were evaluated jointly and analysed by a decision-analytic regret function. Results - A high predictive value was found for the H-reflex examination, but low for the other modalities. When the 5 modalities were evaluated jointly, a non-significant decrease in expected regret from the pre-test situation of 0.96 to a value of 0.93 in post-test situation was revealed. Conclusion - Electrophysiological testing is not sufficient as stand-alone examination in patients with sciatica.

Objectives - To assess the diagnostic value of electrophysiological tests in patients with sciatica. Materials and methods - The diagnostic value of electrophysiological tests were evaluated in 25 patients with mono- radicular sciatica. The electrophysiological study included dermatomal somatosensory evoked potentials, electromyography, F-wave latencies, H- reflexes and motor and sensory nerve conduction determinations. The results of the electrophysiological examinations were evaluated blindly, and the test results were analysed separately by a receiver operating characteristic (ROC) analysis. Furthermore, the 5 modalities were evaluated jointly and analysed by a decision-analytic regret function. Results - A high predictive value was found for the H-reflex examination, but low for the other modalities. When the 5 modalities were evaluated jointly, a non-significant decrease in expected regret from the pre-test situation of 0.96 to a value of 0.93 in post-test situation was revealed. Conclusion - Electrophysiological testing is not sufficient as stand-alone examination in patients with sciatica.