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La holografía es una técnica corrientemente utilizada en el registro de imágenes tridimensionales de objetos que se encuentran tanto en reposo como en movimiento. Sin embargo, la realización de estereogramas por técnicas de Speckle, como en el propuesto en este trabajo, está justificada al tener en consideración el exceso de información normalmente presente en holografía, así como las limitaciones de la visión. La utilización de un láser de colorante pulsado coherente y de energía suficiente permite la obtención de estereograma de objetos en movimiento. El par estereográfico es logrado al registrar simultáneamente dos perspectivas levemente diferentes sobre una película. Mediante un sistema de polarizadores adecuadamente colocados y una pupila compuesta por dos sectores circulares se logra por una imágen formada por un registro de speckle modulados, que al ser iluminada en la reconstrucción, conservan una selectividad angular que permite visualizar en forma independiente ambas perspectivas de la imágen real Fil: Bolognini, N.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina Fil: Duchowicz, R.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina Fil: Scaffardi, L.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina Fil: Trivi, M.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina

El pseudocoloreado consiste en asignar colores arbitrario a los niveles de gris de una imágen blanco y negro. La importancia de esta operación se basa en la mayor eficiencia de la visión humana para distinguir colores que niveles de gris¹ ̍ ³. En esta comunicación se propone un nuevo método de pseudocoloreado que emplea cristales fotorrefractivos⁴ ̍ ⁸ e iluminación incoherente o coherente. La imágen pseudocoloreada se obtiene mediante la superposición de una imágen directa ( en la longitud de onda λ₁) y una imágen de contraste invertido ( en la longitud de onda λ₂). Esta última imágen es producida al leer con λ₂ un cristal BSO polarizado en el cual se registró una imágen del objeto origina con λ₁. Esta imágen induce birrefrigencia en el cristal debido al efecto fotorrefractivo y una apropiada orientación de los polorizadores produce la inversión de contraste. Los resultados experimentales fueron obtenidos con luz blanca filtrada en λ₁ = 5200 Å (registro) y λ₂ = 6350 Å (lectura) (Δλ = 100 Å). Se empleó un voltaje de polarización de 6 kV Fil: Grosz, S. I.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina Fil: Zerbino, L. M.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina Fil: Bolognini, N.. Universidad Nacional de La Plata - CONICET. Centro de Investigaciones Ópticas (CIOP). Buenos Aires. Argentina

The feeling that physical events are caused by us is tied to our action planning rather than being a mere post hoc deduction., Every day, we do things that cause effects in the outside world with little doubt about who caused what. To some, this sense of agency derives from a post hoc reconstruction of a likely causal relationship between an event and our preceding movements; others propose that the sense of agency originates from prospective comparisons of motor programs and their effects. Using functional magnetic resonance imaging, we found that the sense of agency is associated with a brain network including the pre–supplementary motor area (SMA) and dorsal parietal cortex. Transcranial magnetic stimulation affected the sense of agency only when delivered over the pre-SMA and specifically when time-locked to action planning, rather than when the physical consequences of the actions appeared. These findings make a prospective theory of the sense of agency more likely.

Event-related potentials (ERPs) are obtained from the electroencephalogram (EEG) or the magnetoencephalogram (MEG, event-related fields (ERF)), extracting the activity that is time-locked to an event. Despite the potential utility of ERP/ERF in cognitive domain, the clinical standardization of their use is presently undefined for most of procedures. The aim of the present review is to establish limits and reliability of ERP medical application, summarize main methodological issues, and present evidence of clinical application and future improvement. The present section of the review focuses on well-standardized ERP methods, including P300, Contingent Negative Variation (CNV), Mismatch Negativity (MMN), and N400, with a chapter dedicated to laser-evoked potentials (LEPs). One section is dedicated to proactive preparatory brain activity as the Bereitschaftspotential and the prefrontal negativity (BP and pN). The P300 and the MMN potentials have a limited but recognized role in the diagnosis of cognitive impairment and consciousness disorders. LEPs have a well-documented usefulness in the diagnosis of neuropathic pain, with low application in clinical assessment of psychophysiological basis of pain. The other ERP components mentioned here, though largely applied in normal and pathological cases and well standardized, are still confined to the research field. CNV, BP, and pN deserve to be largely tested in movement disorders, just to explain possible functional changes in motor preparation circuits subtending different clinical pictures and responses to treatments.

Multisensory processing can be assessed by measuring susceptibility to crossmodal illusions such as the Sound-Induced Flash Illusion (SIFI). When a single flash is accompanied by 2 or more beeps, it is perceived as multiple flashes (fission illusion); conversely, a fusion illusion is experienced when more flashes are matched with a single beep, leading to the perception of a single flash. Such illusory perceptions are associated to crossmodal changes in visual cortical excitability. Indeed, increasing occipital cortical excitability, by means of transcranial electrical currents, disrupts the SIFI (ie, fission illusion). Similarly, a reduced fission illusion was shown in patients with episodic migraine, especially during the attack, in agreement with the pathophysiological model of cortical hyperexcitability of this disease. If episodic migraine patients present with reduced SIFI especially during the attack, we hypothesize that chronic migraine (CM) patients should consistently report less illusory effects than healthy controls; drugs intake could also affect SIFI. On such a basis, we studied the proneness to SIFI in CM patients (n = 63), including 52 patients with Medication Overuse Headache (MOH), compared to 24 healthy controls. All migraine patients showed reduced fission phenomena than controls (P

Objective: Sound-induced flash illusions depend on visual cortical excitability. In this study, we explored whether sound-induced flash illusions are perceived differently in migraine, a condition associated with pathologic cortical hyperexcitability. Methods: Sound-induced flash illusions were examined in 59 migraine patients (mean age = 32 ± 16 years; 36 females), 32 without aura and 27 with aura, and in 24 healthy controls (mean age = 42 ± 17 years; 16 females). Patients were studied during attacks and interictally. Visual stimuli (flashes) accompanied by sounds (beeps) were presented in different combinations: a single flash with multiple beeps was given to induce the perception of multiple flashes (“fission” illusion), and multiple flashes with a single beep were used to reduce the number of perceived flashes (“fusion” illusion). Results: For migraineurs, the fission illusion was reduced, especially during the attack, and almost abolished when a single flash was combined with 2 beeps (except for those without aura tested interictally); the fusion illusion was less consistently reported in both migraine groups, but not completely disrupted. Conclusions: Results from this study add novel clues to our understanding of visual cortex hyperexcitability in migraine, especially migraine with aura. Furthermore, these analyses underscore how pathologic changes in cortical excitability affect multisensory interactions. Cross-modal illusions represent a valid tool for exploration of functional connectivity between sensory areas, which likely has an important role in the pathophysiology of migraine.

Recent neuropsychological evidence suggests that acquired brain lesions can, in some instances, abolish the ability to integrate inputs from different sensory modalities, disrupting multisensory perception. We explored the ability to perceive multisensory events, in particular the integrity of audio-visual processing in the temporal domain, in brain-damaged patients with visual field defects (VFD), or with unilateral spatial neglect (USN), by assessing their sensitivity to the 'Sound-Induced Flash Illusion' (SIFI). The study yielded two key findings. Firstly, the 'fission' illusion (namely, seeing multiple flashes when a single flash is paired with multiple sounds) is reduced in both left- and right-brain-damaged patients with VFD, but not in right-brain-damaged patients with left USN. The disruption of the fission illusion is proportional to the extent of the occipital damage. Secondly, a reliable 'fusion' illusion (namely, seeing less flashes when a single sound is paired with multiple flashes) is evoked in USN patients, but neither in VFD patients nor in healthy participants. A control experiment showed that the fusion, but not the fission, illusion is lost in older participants (>50 year-old), as compared with younger healthy participants (

Background Despite the relevance of telephone-based cognitive screening tests in clinical practice and research, no specific test assessing executive functioning is available. The present study aimed at standardizing and providing evidence of clinical usability for the Italian telephone-based Frontal Assessment Battery (t-FAB). Methods The t-FAB (ranging 0–12), comprising two subtests, has two versions: one requiring motor responses (t-FAB-M) and the other verbal responses (t-FAB-V). Three hundred and forty-six Italian healthy adults (HPs; 143 males; age range = 18–96 years; education range = 4–23 years) and 40 participants with neurological diseases were recruited. To HPs, the t-FAB was administered along with a set of telephone-based tests: MMSE, verbal fluency (VF), backward digit span (BDS). The in-person version of the FAB was administered to both HPs and clinical groups. Factorial structure, construct validity, inter-rater and test–retest reliability, t-FAB-M vs. t-FAB-V equivalence and diagnostic accuracy were assessed. Norms were derived via Equivalent Scores. Results In HPs, t-FAB measures yielded high inter-rater/test–retest reliability (ICC = .78–.94), were internally related (p ≤ .005) and underpinned by a single component, converging with the telephone-based MMSE, VF, BDS (p ≤ .0013). The two t-FAB versions were statistically equivalent in clinical groups (ps of both equivalence bounds p p ≤ .004). t-FAB scores converge with the in-person FAB in HPs and clinical groups (rs = .43–.78). Both t-FAB versions were accurate in discriminating HPs from the clinical cohort (AUC = .73-.76). Discussion The t-FAB is a normed, valid, reliable and clinically usable telephone-based cognitive screening test to adopt in both clinical and research practice.

Objective The sound-induced flash illusion (SIFI) is a valid paradigm to study multisensorial perception. In the “fission” SIFI, multiple flashes are perceived when observing a single flash paired with two or more beeps. SIFI is largely dependent on visual and acoustic cortex excitability; in migraine, dysfunctional cortical excitability affects SIFI perception. Since estrogen peak occurring during ovulation can increase neuronal excitability, the present study aims to verify whether cortical excitability shifts linked to the menstrual cycle could influence SIFI. Methods In a comparative prospective study, we tested the effect of estrogens on crossmodal perception using the SIFI. We recruited 27 females in reproductive age, including 16 healthy and 11 menstrually related migraine females, testing their proneness to SIFI on day 14 (high estradiol) and day 27 (low estradiol) of menstrual cycle. Results Women on day 14 reported less flashes than on day 27 (p = 0.02) in the fission illusion, suggesting a pro-excitatory effect of estradiol on visual cortex excitability during ovulation. Moreover, we confirmed that migraine women perceived less flashes (p = 0.001) than controls, independently from cycle phase. Non-migraineurs women significantly reported more flashes on day 27 than on day 14 (p = 0.04). Conclusions This study suggests that estradiol may influence the multisensory perception due to changes of visual cortex excitability, with high estradiol peak leading to increased visual cortical sensitivity during ovulation in non-migraineurs. Visual cortex hyperresponsiveness, here reflected by reduced SIFI, is not influenced by estradiol fluctuations in migraine women, as shown by reduced fission effects on day 14 and 27.

The Mini-Balance Evaluation Systems Test (Mini-BESTest), a 14-item scale, has high content validity for balance assessment. This study further examines the construct validity of the Mini-BESTest with an emphasis on its measurement invariance. The Mini-BESTest was administered to 292 neurological patients in two sessions (before and after rehabilitation) and evaluated with the Rasch analysis (Many-Facet Rating Scale Model: persons, items, sessions). Categories’ order and fit to the model were assessed. Next, maps, dimensionality, and differential item functioning (DIF) were examined for construct validity evaluation. DIF was inspected for several clinically important variables, including session, diagnosis, and assistive devices. Mini-BESTest items had ordered categories and fitted the Rasch model. The item map did not flag severe construct underrepresentation. The dimensionality analysis showed that another variable extraneous to balance affected the score of a few items. However, this multidimensionality had only a modest impact on measures. Session did not cause DIF. DIF for assistive devices affected six items and caused a severe measurement artefact. The measurement artefact caused by DIF for diagnosis was negligible. The Mini-BESTest returns interval measures with robust construct validity and measurement invariance. However, caution should be used when comparing Mini-BESTest measures obtained with and without assistive devices.

In the human brain, paired associative stimulation (PAS), a non-invasive brain stimulation technique based on Hebbian learning principles, can be used to model motor resonance, the inner activation of an observer's motor system by action observation. Indeed, the newly developed mirror PAS (m-PAS) protocol, through the repeatedly pairing of transcranial magnetic stimulation (TMS) pulses over the primary motor cortex (M1) and visual stimuli depicting index–finger movements, allows the emergence of a new, atypical pattern of cortico-spinal excitability. In the present study, we performed two experiments to explore (a) the debated hemispheric lateralization of the action-observation network and (b) the behavioral after-effects of m-PAS, particularly concerning a core function of the MNS: automatic imitation. In Experiment 1, healthy participants underwent two sessions of m-PAS, delivered over the right and left M1. Before and after each m-PAS session, motor resonance was assessed by recording motor-evoked potentials induced by single-pulse TMS applied to the right M1 while observing contralateral (left) and ipsilateral (right) index–finger movements or static hands. In Experiment 2, participants performed an imitative compatibility task before and after the m-PAS targeting the right M1. Results showed that only m-PAS targeting the right hemisphere, non-dominant in right-handed people, induced the emergence of motor resonance for the conditioned movement, absent before the stimulation. This effect is not present when m-PAS target the M1 of the left hemisphere. Importantly, the protocol also affects behavior, modulating automatic imitation in a strictly somatotopic fashion (i.e., influencing the imitation of the conditioned finger movement). Overall, this evidence shows that the m-PAS can be used to drive new associations between the perception of actions and their corresponding motor programs, measurable both at a neurophysiological and behavioral level. At least for simple, not goal-directed, movements, the induction of motor resonance and automatic imitation effects are governed by mototopic and somatotopic rules.

Amnesia is a frequent claim in major crimes, and it is estimated that the complete or partial absence of memory following a crime ranges from 25% to 50% of total cases. Although some cases may constitute a genuine form of amnesia, due to organic-neurological defects or psychological causes, and possibly combined with a dissociative or repressive coping style after an extreme experience, malingering is still fairly common in offenders. Therefore, one of the main goals in medico-legal proceedings is to find methods to determine the credibility of crime-related amnesia. At present, a number of lie and memory detection techniques can assist the forensic assessment of the reliability of declarative proof, and have been devised and improved over the past century: for example, modern polygraphs, event-related potentials, thermal imaging, functional magnetic resonance imaging, kinematic, and facial analysis. Other ad hoc psychological tests, such as the so-called Symptom Validity Test (SVT) and Performance Validity Test (PVT), as well as the autobiographical Implicit Association Test (aIAT), can also be used. To date, however, there is little evidence or case reports that document their real usefulness in forensic practice. Here, we report two cases of crime-related amnesia, whereby both defendants, who were found guilty of homicide, appeared to exhibit dissociative amnesia but where the application of SVTs, PVTs, and aIAT detected a malingered amnesia.

Background: To quantify the degree of ganglion cell degeneration through spectral domain optical coherence tomography (SD-OCT) in adult patients with post-stroke homonymous visual field defect. Methods: Fifty patients with acquired visual field defect due to stroke (mean age = 61 years) and thirty healthy controls (mean age = 58 years) were included. Mean deviation (MD) and pattern standard deviation (PSD), average peripapillary retinal nerve fibre layer thickness (pRNLF-AVG), average ganglion cell complex thickness (GCC-AVG), global loss volume (GLV) and focal loss volume (FLV) were measured. Patients were divided according to the damaged vascular territories (occipital vs. parieto-occipital) and stroke type (ischaemic vs. haemorrhagic). Group analysis was conducted with ANOVA and multiple regressions. Results: pRNFL-AVG was significantly decreased among patients with lesions in parieto-occipital territories compared to controls and to patients with lesions in occipital territories (p =.04), with no differences with respect to stroke type. GCC-AVG, GLV and FLV differed in stroke patients and controls, regardless of stroke type and involved vascular territories. Age and elapsed time from stroke had a significant effect on pRNFL-AVG and GCC-AVG (p

Seminal studies in monkeys report that the viewing of actions performed by other individuals activates frontal and parietal cortical areas typically involved in action planning and execution [1-3]. That mirroring actions might rely on both motor and somatosensory components is suggested by reports that action observation and execution increase neural activity in motor [4-13] and in somatosensory areas [8-10, 14-17]. This occurs not only during observation of naturalistic movements [4-17] but also during the viewing of biomechanically impossible movements that tap the afferent component of action, possibly by eliciting strong somatic feelings in the onlooker [18, 19]. Although somatosensory feedback is inherently linked to action execution [20], information on the possible causative role of frontal and parietal cortices in simulating motor and sensory action components is lacking. By combining low-frequency repetitive and single-pulse transcranial magnetic stimulation, we found that virtual lesions of ventral premotor cortex (vPMc) and primary somatosensory cortex (S1) suppressed mirror motor facilitation contingent upon observation of possible and impossible movements, respectively. In contrast, virtual lesions of primary motor cortex did not influence mirror motor facilitation. The reported double dissociation suggests that vPMc and S1 play an active, differential role in simulating efferent and afferent components of observed actions. © 2007 Elsevier Ltd. All rights reserved.

Background The Italian telephone-based Mini-Mental State Examination (Itel-MMSE), despite being psychometrically sound, has shown relevant ceiling effects, which may negatively impact the interpretation of its scores. In address to overcome such an issue, this study aimed at providing item-level insights on the Itel-MMSE through Item Response Theory (IRT) analyses. Methods Five-hundred and sixty-seven healthy Italian adults (227 males, 340 females; mean age: 51 ± 17 years, range 18–96; mean education: 13.31 ± 4.3 years). A two-parameter logistic IRT model was implemented to assess item discrimination and difficulty of the Itel-MMSE. Construct unidimensionality, statistical independence of items, and model and item fit were tested. Informativity levels were also assessed graphically. Results With respect to the Itel-MMSE total score, ceiling effects were found in 92.7% of participants. Unidimensionality was violated; both model and item fit were poor; a few items showed statistical dependence. Both the whole test and its items proved to be scarcely informative, especially for medium-to-high levels of ability, except for attention and spatial orientation subtests, which consistently yielded the highest discriminative capability. Discussion The Itel-MMSE appears to be most informative in low-performing healthy individuals. However, the present findings should not lead practitioners to aprioristically equate ceiling effects/low informativity to clinical uselessness. Items assessing attention and, to a lesser extent, spatial orientation appear to be the most informative. Supplementary Information The online version contains supplementary material available at 10.1007/s40520-021-02041-4.

Background Telephone-based cognitive screening (TBCS) is crucial to telehealth care of neurological patients, prevention campaigns, and epidemiological studies on cognitive impairment. The Telephone Interview for Cognitive Status (TICS) is one of the most widespread and psychometrically/diagnostically sound TBCS test, with several versions developed worldwide (e.g., with and without a delayed recall item). In Italy, only attempts of adaptation and preliminary evidence of its statistical features have been provided so far. This study thus aimed at (1) developing an Italian version of the TICS and assessing its (2) psychometric and (3) diagnostic properties. Methods A back-translated and culturally adapted version of the TICS was developed. Three-hundred and sixty-five healthy individuals from different regions of Italy (147 males, 216 females; age: 53.2 ± 16 years; education: 13 ± 4.5 years) were administered the TICS and the Italian telephone-based Mini-Mental State Examination (Itel-MMSE). Validity was tested by convergence and at the structure level, whereas reliability as internal consistency, test–retest, and inter-rater. Diagnostic accuracy, item difficulty, and discrimination were also examined. Results The TICS featured a single component and its score converged with that of the Itel-MMSE (rs = .37). Reliability was excellent as inter-rater (ICC = .94), good as test–retest (ICC = .78), and acceptable as internal consistency (Cronbach’s α = .63). Accuracy was high as tested against the Itel-MMSE (AUC = .83) and did not improve when adding the delayed recall. Backward subtraction was the most difficult and discriminative task. Discussion The Italian TICS is a valid, reliable, and diagnostically accurate TBCS test. The original format of the TICS can be thus adopted in both clinical and research settings. Supplementary Information The online version contains supplementary material available at 10.1007/s10072-021-05729-7.

Chronic migraine is a burdensome disease presenting with episodic pain and several symptoms that may persist even among headache attacks. Multisensory integration is modified in migraine, as assessed by the level of the perception of sound-induced flash illusions, a simple paradigm reflecting changes in cortical excitability which reveals to be altered in migraineurs. OnabotulinumtoxinA is an effective preventive therapy for chronic migraineurs, reducing peripheral and central sensitization, and may influence cortical excitability. Patients affected by chronic migraine who started onabotulinumtoxinA preventive therapy were included. Clinical effects (headache diaries and migraine related questionnaires) were assessed at the beginning of the therapy and after 12 weeks. Contextually, patients underwent the evaluation of multisensory perception by means of the sound-induced flash illusions. OnabotulinumtoxinA showed effectiveness both in migraine prevention and in reducing headache burden. Even one session of therapy was able to restore, at least partially, multisensory processing, as shown by patients’ susceptibility to the sound-induced flash illusion. OnabotulinumtoxinA could influence migraineurs cortical excitability concurrently to the beneficial effects in headache prevention.

Paired associative stimulation (PAS) protocols can be used to induce Hebbian plasticity in the human brain. A modified, cross-modal version, of the PAS (cross-modal PAS, cm-PAS) has been recently developed. The cm-PAS consists in the repetitive pairings of a transcranial magnetic stimulation (TMS) pulse over the primary somatosensory cortex (S1) and a visual stimulus depicting a hand being touched; a 20 ms of inter-stimulus interval (ISI) is required to affect S1 plasticity, in turn modulating tactile acuity and somatosensory evoked potentials. The present study explores the role of anticipatory simulation in the cm-PAS efficacy, which could be responsible for such a short ISI. To this aim, we compared the effect of the original, fixed-frequency, cm-PAS to that of a jittered version, in which the time interval between trials was not steady but jittered, hence avoiding the anticipation of the upcoming visual-touch stimulus. Moreover, in the jittered PAS, the ISI between the paired stimulations was varied: it could match the early, somatosensory-driven, activation of S1 (20 ms), or the mirror recruitment of S1 by touch observation (150 ms). Results showed that tactile acuity is enhanced by the fixed-frequency cm-PAS, with an ISI of 20 ms between paired stimulation (visual-touch stimulus and TMS pulse over S1), and also by the jittered cm-PAS but only if the ISI is of 150 ms. These findings suggest that the cm-PAS with a jittered frequency, by preventing an anticipatory pre-activation of S1, delays the timing of the interaction between the visual-touch stimulus and the cortical pulse. On a broader perspective, our study highlights the possible involvement of sensory anticipation, likely through mirror-like simulation mechanisms, in tactile mirroring, as well as its influence of the optimal interval between the afferent and the magnetic pulse during PAS protocols.