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Mental Time Travel (MTT) allows us to remember past events and imagine future ones. According to previous literature, the Temporal Distance of events affects MTT: our ability to order events worsens for close, compared to far, events. However, those studies established distances a-priori, albeit the way we perceive events' temporal distance may subjectively differ from their objective distance. Thus, in the current study, we aimed to investigate the effects of Perceived Temporal Distance (PTD) on the MTT ability and the brain areas mediating this process. Thirty-three healthy volunteers took part in an fMRI MTT task. Participants were asked to project themselves into the past, present, or future, and to judge a series of events as relative-past or relative-future, in relation to the adopted time location. Outside the scanner, participants provided PTD estimates for each stimulus of the MTT task. Participants' performance and functional activity were analyzed as a function of these estimations. At the behavioural level, PTD predicts the modulation of the performance for relative-past and relative-future. Bilateral angular gyrus, retrosplenial cortex, temporo-parietal region and medial, middle and superior frontal gyri mediate the PTD effect. In addition to these areas, the closer the relative-future events are perceived, the higher the involvement of left parahippocampal and lingual gyri and right cerebellum. Thus, perceived proximity of events activates frontal and posterior parietal areas, which therefore might mediate the processing of PTD in the cognitive spatial representation of time. Future proximity also activates cerebellum and medial temporal areas, known to be involved in imaginative and constructive cognitive functions. [ABSTRACT FROM AUTHOR]

Hypersexuality in medicated patients with PD is caused by an increased influence of motivational drive areas and a decreased influence of inhibitory control areas due to dopaminergic medication. In this pilot study, we test a newly developed paradigm investigating the influence of dopaminergic medication on brain activation elicited by sexual pictures with and without inhibitory contextual framing. Twenty PD patients with and without hypersexuality were examined with fMRI either OFF or ON standardized dopaminergic medication. The paradigm consisted of a priming phase where either a neutral context or an inhibitory context was presented. This priming phase was either followed by a sexual or a neutral target. Sexual, compared to neutral pictures resulted in a BOLD activation of various brain regions implicated in sexual processing. Hypersexual PD patients showed increased activity compared to PD controls in these regions. There was no relevant effect of medication between the two groups. The inhibitory context elicited less activation in inhibition-related areas in hypersexual PD, but had no influence on the perception of sexual cues. The paradigm partially worked: reactivity of motivational brain areas to sexual cues was increased in hypersexual PD and inhibitory contextual framing lead to decreased activation of inhibitory control areas in PD. We could not find a medication effect and the length of the inhibitory stimulus was not optimal to suppress reactivity to sexual cues. Our data provide new insights into the mechanisms of hypersexuality and warrant a replication with a greater cohort and an optimized stimulus length in the future. [ABSTRACT FROM AUTHOR]

The present study examined the impact of white noise on word recall performance and brain activity in 40 healthy adolescents, split in two groups (normal and low) depending on their auditory working memory capacity (AWMC). Using functional magnetic resonance imaging, participants performed a backward recall task under four different signal-to-noise ratio (SNR) conditions: 15, 10, 5, and 0-dB SNR. Behaviorally, normal AWMC individuals scored significantly higher than low AWMC individuals across noise levels. Whole-brain analyses showed brain activation not to be statistically different between groups across noise levels. In the normal group, a significant positive relationship was found between performance and number of activated voxels in the right superior frontal gyrus. In the low group, significant positive correlations were found between performance and number of activated voxels in left superior frontal gyrus, left inferior frontal gyrus, and left anterior cingulate cortex. These findings suggest that the strategic structure involved in the enhancement of AWM performance may differ in normal and low AWMC individuals. [ABSTRACT FROM AUTHOR]

Although learning and adapting to visuo-motor tasks is critical to child development and health conditions requiring rehabilitation, the neural processes involved in learning a new visuo-motor task and adapting it to novel conditions such as execution with an untrained limb are not fully understood. Therefore, we trained 27 healthy, right-hand-dominant individuals aged 18–35 years to perform a multidirectional point-to-point visually rotated aiming task with a joystick during functional magnetic resonance imaging, with 13 participants learning the task with the dominant (D) and 14 with the non-dominant (ND) hand. All individuals performed the task with the trained and untrained hand before and after training. As expected, performance of both the trained and the untrained hand improved significantly over the course of task acquisition. Brain functional changes associated with adaptation to the demands of the task, and execution differed significantly between D and ND groups. In particular, the ND group showed greater recruitment of visual and motor regions (left middle occipital and left precentral gyri) than the D group during task acquisition. In addition, the D group exhibited greater recruitment of motor planning regions (left precuneus) that contribute to performance with the trained hand, even after bilateral transfer—switching from the trained to non-trained hand. The D group showed more persistence of activation in sensorimotor regions—greater activation when returning to the rotated task after a switching to a simpler, non-rotated aiming task for a short interval. Finally, the D group showed more activation after-effects—increases in simpler task activation after training on the visually rotated task. The findings suggest that brain functional changes associated with adaptation to a visuo-motor skill may differ substantially depending on whether the dominant or non-dominant hand is trained, with non-dominant-hand training associated with greater activation during acquisition, and dominant-hand training associated with greater activation during bilateral transfer, persistence, and after-effects. [ABSTRACT FROM AUTHOR]

Stroke has been associated with many changes in motor system function, but there has been limited study of changes in somatotopic organization. This was examined in a group of patients with cortical stroke affecting primary sensorimotor cortex. In 17 patients with good outcome after cortical stroke involving precentral and/or postcentral gyri, plus 14 controls, four functional MRI evaluations of brain activity were obtained: finger, shoulder, and face motor tasks plus a sensory task, passive finger motion. For each, coordinates for contralateral primary sensorimotor cortex activation site were determined, as was a measure of inter-hemispheric balance. The normal motor somatotopy measured in controls was largely preserved after stroke. The main difference found between controls and patients was that the face was lateral to finger motor activation in all controls, but face was centered medial to finger in 43% of patients. Among patients, smaller infarct volume was associated with more ventral, and larger infarct with more dorsal, contralateral primary sensorimotor cortex activation. On the other hand, better behavioral outcome was associated with a more posterior, and poorer outcome with more anterior, activation. Larger infarct and poorer behavioral outcome were each associated with a change in inter-hemispheric balance towards the non-stroke hemisphere. Shifts in contralateral movement representation site did not correlate with changes in inter-hemispheric balance. Motor somatotopy is generally preserved after injury to primary sensorimotor cortex. Greater injury and larger behavioral deficits are associated with distinct effects on movement representation sites. Changes in motor organization within and between hemispheres arise independently after stroke.

Botulinum toxin type A (BoNT) is considered an effective therapeutic option in cervical dystonia (CD). The pathophysiology of CD and other focal dystonias has not yet been fully explained. Results from neurophysiological and imaging studies suggest a significant involvement of the basal ganglia and thalamus, and functional abnormalities in premotor and primary sensorimotor cortical areas are considered a crucial factor in the development of focal dystonias. Twelve BoNT-naïve patients with CD were examined with functional MRI during a skilled hand motor task; the examination was repeated 4 weeks after the first BoNT injection to the dystonic neck muscles. Twelve age- and gender-matched healthy controls were examined using the same functional MRI paradigm without BoNT injection. In BoNT-naïve patients with CD, BoNT treatment was associated with a significant increase of activation in finger movement-induced fMRI activation of several brain areas, especially in the bilateral primary and secondary somatosensory cortex, bilateral superior and inferior parietal lobule, bilateral SMA and premotor cortex, predominantly contralateral primary motor cortex, bilateral anterior cingulate cortex, ipsilateral thalamus, insula, putamen, and in the central part of cerebellum, close to the vermis. The results of the study support observations that the BoNT effect may have a correlate in the central nervous system level, and this effect may not be limited to cortical and subcortical representations of the treated muscles. The results show that abnormalities in sensorimotor activation extend beyond circuits controlling the affected body parts in CD even the first BoNT injection is associated with changes in sensorimotor activation. The differences in activation between patients with CD after treatment and healthy controls at baseline were no longer present. [ABSTRACT FROM AUTHOR]

Acquired auditory-visual synesthesia (AVS) is a rare neurological sign, in which specific auditory stimulation triggers visual experience. In this study, we used event-related fMRI to explore the brain regions correlated with acquired monocular sound-induced phosphenes, which occurred 2 months after unilateral visual loss due to an ischemic optic neuropathy. During the fMRI session, 1-s pure tones at various pitches were presented to the patient, who was asked to report occurrence of sound-induced phosphenes by pressing one of the two buttons (yes/no). The brain activation during phosphene-experienced trials was contrasted with non-phosphene trials and compared to results obtained in one healthy control subject who underwent the same fMRI protocol. Our results suggest, for the first time, that acquired AVS occurring after visual impairment is associated with bilateral activation of primary and secondary visual cortex, possibly due to cross-wiring between auditory and visual sensory modalities. [ABSTRACT FROM AUTHOR]

Previous fMRI studies related to emotional conflict focused on task activation during the specific experimental paradigm. Yet, the underlying spontaneous neural activity was largely unknown. Here, this was the first study using resting-state fMRI to explore the spontaneous neural activity related to emotional conflict. We used the whole-brain analysis to investigate the association between emotional conflict and amplitude of low-frequency fluctuations (ALFF) in a large sample. We found that the emotional conflict effect was negatively correlated with ALFF in the right AMY. These findings implied that AMY was the key region which plays a crucial role in emotional conflict. [ABSTRACT FROM AUTHOR]

We have previously established an fMRI task battery suitable for mapping the language processing network in children. Among the tasks used, the synonyms and the vowel identification task induced robust task-related activations in children with average language abilities; however, the fixed presentation time seems to be a drawback in participants with above- or below-average language abilities. This feasibility study in healthy adults ( n = 20) was aimed at adapting these tasks to the individual level of each patient by implementing a self-paced stimulus presentation. The impact of using a block- versus an event-related statistical approach was also evaluated. The self-paced modification allowed our participants with above-average language abilities to process stimuli much faster than originally implemented, likely increasing task adherence. A higher specificity of the event-related analysis was confirmed by stronger left inferior frontal and crossed cerebellar activations. We suggest that self-paced paradigms and event-related analyses may both increase specificity and applicability. [ABSTRACT FROM AUTHOR]

The primary taste cortex is located in the insula. However, exactly where in the insula the human primary taste cortex is located remains a controversial issue. Human neuroimaging studies have shown prominent variation concerning the location of taste-responsive activation within the insula. A standard protocol for gustatory testing in neuroimaging studies has not been developed, which might underlie such variations. In order to localize the primary taste cortex in an fMRI experiment, we used a taste delivery system to suppress non-taste stimuli and psychological effects. Then, we compared brain response to taste solution during a passive tasting task condition and a taste quality identification task condition to verify whether this cognitive task affected the location of taste-responsive activation within the insula. To examine which part of insula is the primary taste area, we performed dynamic causal modeling (DCM) to verify the neural network of the taste coding-related region and random-effects Bayesian model selection (BMS) at the family level to reveal the optimal input region. Passive tasting resulted in activation of the right middle insula (MI), and the most favorable model selected by DCM analysis showed that taste effect directly influenced the MI. Additionally, BMS results at the family level suggested that the taste inputs entered into the MI. Taken together, our results suggest that the human primary taste cortex is located in the MI. [ABSTRACT FROM AUTHOR]

Object-directed action consists of aspects that range from low-level kinematic patterns to high-level action goals. Although previous studies have suggested that the human mirror neuron system (MNS) is involved in understanding or imitating an observed action, it is unclear precisely which levels of action representation are reflected in MNS activity. In this study, we used an imitation-matching task, which is previously used in behavioral experiments for infants, and fMRI to reveal the neural basis for imitation of multiple representations of observed actions. In our experiment, two video footages showing a pen being grasped and placed into one of two cups were sequentially presented. The participants judged whether an actor's action in the first movie was correctly imitated by an imitator in the second movie, regarding the following four aspects: action goal, a means of manipulation, an effector used, and movement trajectory. Although identical sets of stimuli were presented, different brain regions were activated, depending on the matching judgments made by subjects between the two actions. The current study indicates that distinct brain regions are involved in recognition of multiple aspects of transitive actions, which is largely consistent with a visuomotor circuit of action production by the observer. [ABSTRACT FROM AUTHOR]

Coordination of actions according to the request of another person is frequently observed in daily life. The purpose of this study is to elucidate the neural mechanisms related to the processing of this type of interpersonal action coordination by using functional magnetic resonance imaging (fMRI). In the first experiment, participants viewed movie clips depicting two people (1st and 3rd person) involved in a joint-action situation: one person (passive agent) holding two objects asked the other person to take one object; the other person (active agent) then performing a congruent or incongruent action with regard to the request. fMRI results showed that the right inferior frontal gyrus (IFG) and right cerebellum were more activated during the observation of incongruent actions than that of congruent actions. Greater activation in the right posterior superior temporal sulcus (pSTS) and the medial prefrontal cortex (mPFC) were also found in the same contrast after small volume correction (SVC). In the second experiment, in which only the active person appeared in the movie clip (single-action situation), no significant activation in the right IFG and right cerebellum was found, although greater activation in the right pSTS and the mPFC was found during the observation of the incongruent action than that of the congruent action after SVC. Our study suggests that the right IFG, which is assumed to be a part of the mirror neuron system, is involved in understanding interpersonal action congruency. [ABSTRACT FROM AUTHOR]

It is widely accepted that regions within the dorsal medial frontal cortex are involved in the control of voluntary action. However, recent evidence suggests that a subset of these regions may also be important for unconscious and involuntary motor processes. Indeed, Sumner et al. (Neuron 54:697-711, 2007) showed that two patients with micro-lesions of the supplementary motor area (SMA) and supplementary eye field (SEF) demonstrated an absence of unconscious inhibition as evoked by masked-prime stimuli, while pre-SMA damage had no such effect. Here, we employ fMRI and a similar masked-prime task to test whether SMA and pre-SMA are similarly dissociated in healthy volunteers. Reaction times (RT) revealed that responses to compatible trials were slower than those to incompatible trials (negative compatibility effect, NCE), indicating automatic inhibition in every participant. BOLD signals in the SMA were modulated by prime compatibility, showing greater signal for compatible trials, but there was no change in pre-SMA. There was also no modulation in the hand motor cortex (HMC). These findings imply that the SMA is involved in automatic suppression of manual motor plans. [ABSTRACT FROM AUTHOR]

Worldwide, ethanol abuse causes thousands of fatal accidents annually as well as innumerable social dysfunctions and severe medical disorders. Yet, few studies have used the blood oxygenation level dependent functional magnetic resonance imaging method (BOLD fMRI) to map how alcohol alters brain functions, as fMRI relies on neurovascular coupling, which may change due to the vasoactive properties of alcohol. We monitored the hemodynamic response function (HRF) with a high temporal resolution. In both motor cortices and the visual cortex, alcohol prolonged the time course of the HRF, indicating an overall slow-down of neurovascular coupling rather than an isolated reduction in neuronal activity. However, in the supplementary motor area, alcohol-induced changes to the HRF suggest a reduced neuronal activation. This may explain why initiating and coordinating complex movements, including speech production, are often impaired earlier than executing basic motor patterns. Furthermore, the present study revealed a potential pitfall associated with the statistical interpretation of pharmacological fMRI studies based on the general linear model: if the functional form of the HRF is changed between the conditions data may be erroneously interpreted as increased or decreased neuronal activation. Thus, our study not only presents an additional key to how alcohol affects the network of brain functions but also implies that potential changes to neurovascular coupling have to be taken into account when interpreting BOLD fMRI. Therefore, measuring individual drug-induced HRF changes is recommended for pharmacological fMRI. [ABSTRACT FROM AUTHOR]

Although several features of brain motor function appear to be preserved even in chronic complete SCI, previous functional MRI (fMRI) studies have also identified significant derangements such as a strongly reduced volume of activation, a poor modulation of function and abnormal activation patterns. It might be speculated that extensive motor imagery training may serve to prevent such abnormalities. We here report on a unique patient with a complete traumatic SCI below C5 who learned to elicit electroencephalographic signals β-bursts in the midline region upon imagination of foot movements. This enabled him to use a neuroprosthesis and to “walk from thought” in a virtual environment via a brain–computer interface (BCI). We here used fMRI at 3T during imagined hand and foot movements to investigate the effects of motor imagery via persistent BCI training over 8 years on brain motor function and compared these findings to a group of five untrained healthy age-matched volunteers during executed and imagined movements. We observed robust primary sensorimotor cortex (SMC) activity in expected somatotopy in the tetraplegic patient upon movement imagination while such activation was absent in healthy untrained controls. Sensorimotor network activation with motor imagery in the patient (including SMC contralateral to and the cerebellum ipsilateral to the imagined side of movement as well as supplementary motor areas) was very similar to the pattern observed with actual movement in the controls. We interpret our findings as evidence that BCI training as a conduit of motor imagery training may assist in maintaining access to SMC in largely preserved somatopy despite complete deafferentation. [ABSTRACT FROM AUTHOR]

We investigated the effects of social content of gestures on brain activation patterns. We used a 3 × 3 × 3 factorial design in an event-related functional magnetic resonance imaging experiment with participants observing gestures varied by type (fascist salute, wave, or arm lift), number of images shown at a time, and face frequency. We sought to determine whether increasing the social content of the gesture spreads activation from traditional sensorimotor regions engaged in mirror neuron activity to prefrontal regions concerned with social behavior. Results indicate that viewing a highly provocative gesture (fascist salute) compared to a less provocative but still socially meaningful gesture (wave) reveals activation in prefrontal and limbic areas. In addition, as expected there was more inferior frontal gyrus activation when participants observed a greater number of gesturing actors. Additionally, the psychological characteristics of shame and defeat affected activation in the inferior parietal lobe, which is part of the mirror neuron system, for the fascist salute compared to the wave contrast. We conclude that observing social gestures activates social- and emotion-processing areas of the brain, and the activation varies depending on the observer’s psychological characteristics. [ABSTRACT FROM AUTHOR]

The brain uses gaze orientation to organize myriad spatial tasks including hand movements. However, the neural correlates of gaze signals and their interaction with brain systems for arm movement control remain unresolved. Many studies have shown that gaze orientation modifies neuronal spike discharge in monkeys and activation in humans related to reaching and finger movements in parietal and frontal areas. To continue earlier studies that addressed interaction of horizontal gaze and hand movements in humans (Baker et al. ), we assessed how horizontal and vertical gaze deviations modified finger-related activation, hypothesizing that areas throughout the brain would exhibit movement-related activation that depended on gaze angle. The results indicated finger movement-related activation related to combinations of horizontal, vertical, and diagonal gaze deviations. We extended our prior findings to observation of these gaze-dependent effects in visual cortex, parietal cortex, motor, supplementary motor area, putamen, and cerebellum. Most significantly, we found a modulation bias for increased activation toward rightward, upper-right and vertically upward gaze deviations. Our results indicate that gaze modulation of finger movement-related regions in the human brain is spatially organized and could subserve sensorimotor transformations. [ABSTRACT FROM AUTHOR]

Using an uncertainty paradigm and functional magnetic resonance imaging (fMRI) we studied the effect of nonspatial selective and divided visual attention on the activity of specific areas of human extrastriate visual cortex. The stimuli were single ovals that differed from an implicit standard oval in either colour or width. The subjects’ task was to classify the current stimulus as one of two possible alternatives per stimulus dimension. Three different experimental conditions were conducted: “colour-certainty”, “shape-certainty” and “uncertainty”. In all experimental conditions, the stimulus differed in only one stimulus dimension per trial. In the two certainty conditions, the subjects knew in advance which dimension this would be. During the uncertainty condition they had no such previous knowledge and had to monitor both dimensions simultaneously. Statistical analysis of the fMRI data (with SPM2) revealed a modest effect of the attended stimulus dimension on the neural activity in colour sensitive area V4 (more activity during attention to colour) and in shape sensitive area LOC (more activity during attention to shape). Furthermore, cortical areas known to be related to attention and working memory processes (e.g., lateral prefrontal and posterior parietal cortex) exhibit higher activity during the condition of divided attention (“uncertainty”) than during that of selective attention (“certainty”). [ABSTRACT FROM AUTHOR]

The spatial location of activation for writing individual letters and for writing simple dots was studied using event-related functional MRI. Ten healthy right-handed subjects were scanned while performing two different protocols with self-paced repetitive movement. In the first protocol with self-paced dot writing, we observed significant activation in regions known to participate in motor control: contralateral to the movement in the primary sensorimotor and supramarginal cortices, the supplementary motor area (SMA) with the underlying cingulate, in the thalamus and, to a lesser extent, in the ipsilateral inferior parietal and occipital cortices. In the second protocol, we investigated an elemental writing feature—writing single letters. We observed statistically significant changes in the premotor, sensorimotor and supramarginal cortices, the SMA and the thalamus with left predominance, and in the bilateral premotor and inferior/superior parietal cortices. The parietal region that was active during the writing of single letters spanned the border between the parietal superior and inferior lobuli Brodmann area (BA 2, 40), deep in the intraparietal sulcus, with a surprising right-sided dominance. The direct comparison of the results of the two protocols was not significant with a confidence level of P<0.05 corrected for whole brain volume. Thus, the ROI approach was used, and we tried to find significant differences within the two predefined regions of interest (ROI) (BA 7, BA 37). The differences were found with a confidence level of P<0.05 corrected for the volume of these predicted areas. The ROI were located in the posterior parts of hemispheres, in the ventral and in the dorsal visual pathway. The right-sided posterior cortices may play a role in the elemental mechanisms of writing. It is possible that activation of this region is linked with the spatial dimension of the writing. [ABSTRACT FROM AUTHOR]

Functional MRI (fMRI) combined with the paired-stimuli paradigms (referred as dynamic fMRI) was used to study the “illusory double-flash” effect on brain activity in the human visual cortex. Three experiments were designed. The first two experiments aimed to examine the cross-modal neural interaction between the visual and auditory sensory systems caused by the illusory double-flash effect using combined auditory (beep sound) and visual (light flash) stimuli. The fMRI signal in the visual cortex was significantly increased in response to the illusory double flashes compared to the physical single flash when the inter-stimuli delay between the auditory and visual stimuli was 25 ms. This increase disappeared when the delay was prolonged to ~300 ms. These results reveal that the illusory double-flash effect can significantly affect the brain activity in the visual cortex, and the degree of this effect is dynamically sensitive to the inter-stimuli delay. The third experiment was to address the spatial differentiation of brain activation in the visual cortex in response to the illusory double-flash stimulation. It was found that the illusory double-flash effect in the human visual cortex is much stronger in the periphery than the fovea. This finding suggests that the periphery may be involved in high-level brain processing beyond the retinotopic visual perception. The behavioral measures conducted in this study indicate an excellent correlation between the fMRI results and behavioral performance. Finally, this work demonstrates a unique merit of fMRI for providing both temporal and spatial information regarding cross-modal neural interaction between different sensory systems. [ABSTRACT FROM AUTHOR]

We have compared functional MRI signals in primary sensorimotor cortex (SM1) during a paced motor task of each hand before and after unimanual (right hand) fatiguing exercise. Our aims were to determine whether the degree of activation is different when a motor task is performed after a fatiguing exercise, and whether there are any differences in activation between movement of the fatigued and non-fatigued hands. There was a significant reduction in the number of voxels activated in SM1 in the hemisphere contralateral to movement of both the fatigued hand (38±5 pre-exercise versus 21±3 post-exercise; P<0.05) and the non-fatigued hand (32±4 pre-exercise vs 18±4 post-exercise; P<0.05). There was no significant difference in the magnitude of the functional magnetic resonance imaging signal before or after exercise, however, the variance increased significantly after exercise (6.0±0.5 pre-exercise vs 7.3±0.6 post-exercise; P<0.01). Reduced functional activation in SM1 may reflect increased variability in the activation rather than a reduction in activation of cortical motor networks after fatigue. [ABSTRACT FROM AUTHOR]

The objective of this study was to define cortical and subcortical structures activated during both active and passive movements of the ankle, which have a fundamental role in the physiology of locomotion, to improve our understanding of brain sensorimotor integration. Sixteen healthy subjects, all right-foot dominant, performed a dorsi-plantar flexion task of the foot using a custom-made wooden manipulandum, which enabled measurements of the movement amplitude. All subjects underwent a training session, which included surface electromyography, and were able to relax completely during passive movements. Patterns of activation during active and passive movements and differences between functional MRI (fMRI) responses for the two types of movement were assessed. Regions of common activation during the active and passive movements were identified by conjunction analysis. We found that passive movements activated cortical regions that were usually similar in location to those activated by active movements, although the extent of the activations was more limited with passive movements. Active movements of both feet generated greater activation than passive movements in some regions (such as the ipsilateral primary motor cortex) identified in previous studies as being important for motor planning. Common activations during active and passive movements were found not only in the contralateral primary motor and sensory cortices, but also in the premotor cortical regions (such as the bilateral rolandic operculum and contralateral supplementary motor area), and in the subcortical regions (such as the ipsilateral cerebellum and contralateral putamen), suggesting that these regions participate in sensorimotor integration for ankle movements. In future, similar fMRI studies using passive movements have potential to elucidate abnormalities of sensorimotor integration in central nervous system diseases that affect motor function. [ABSTRACT FROM AUTHOR]

Small-field optokinetic nystagmus (OKN) was performed in seven healthy volunteers in order to analyze the activation and deactivation patterns of visual motion, ocular motor, and multisensory vestibular cortex areas by means of fMRI during coherent visual motion stimulation. BOLD signal decreases (deactivations) were found in the first and second long insular gyri and retroinsular areas (the human homologue of the parietoinsular vestibular cortex and the visual posterior sylvian area in the monkey) of both hemispheres, extending into the transverse temporal gyrus and inferior-anterior parts of the superior temporal gyrus (BA 22), and the precentral gyri at two separate sites (BA 4 and 6). Further deactivations were found in cranioposterior parts of the superior temporal gyrus (BA 22) and the adjacent inferior parietal lobule (BA 40), anterior cingulate gyrus, hippocampus, and corpus callosum. Most of these BOLD signal decreases involved parts of the "multisensory vestibular cortical circuit". These findings support the concept of a reciprocally inhibitory visual–vestibular interaction that has now been demonstrated not only for large-field visual motion stimulation that induces vection (without eye movements) but also for optokinetically induced eye movements (without vection). The functional significance of this concept may be related to the perception of self-motion, since both large-field visual motion stimulation and optokinetic nystagmus are linked to the visual control of self-motion. With respect to activation of the cortical ocular motor system two separate and distinct areas of activations were delineated in the precentral sulcus of both hemispheres, one ventrolaterally (in BA 9) and the other dorsomedially at the junction of the superior frontal sulcus with the precentral sulcus (in BA 6). Both probably correspond to different subregions of the frontal eye field and the premotor cortex for the ocular motor performance of OKN. [ABSTRACT FROM AUTHOR]

We examined brain activation patterns occurring during the production and encoding of a motor sequence. Participants performed a variant of the serial reaction-time task under two conditions. The first condition was designed to foster the engagement of explicit mechanisms of knowledge acquisition. The second condition was intended to encourage the engagement of implicit learning mechanisms that would be more typical of the standard serial reaction-time task. In the first condition, the acquisition of explicit knowledge about an 8-element ordered sequence led to a significant and rapid decline in reaction time. By contrast, the second condition, the task in which a sequence was presented unbeknownst to participants, did not yield changes in reaction time. Several brain regions, including prefrontal cortex, superior and inferior parietal lobules, and cerebellum, exhibited explicit learning-related activation. The prefrontal cortex and inferior parietal lobules increased their levels of activation between the beginning and end of the experiment, while primary motor, primary sensory, and cerebellar cortex decreased their levels of activation from the beginning to the end of the experiment. We propose a model in which two processes, a learning-related increase and a habituation process might interact to produce the activation patterns observed during movement sequence acquisition. In short, the prefrontal cortex and inferior parietal lobule together direct and recruit superior parietal lobule and cerebellum to encode and perform the sequence. The increased activation in prefrontal cortex and inferior parietal lobule may represent the activity of a working memory circuit that functions in the acquisition and recall of sequence information. [ABSTRACT FROM AUTHOR]

Working memory refers to the short-term retention of information that is no longer accessible in the environment, and the manipulation of this information, for subsequent use in guiding behavior. In this review, we will present data from a series of event-related functional magnetic-resonance-imaging (fMRI) studies of delayed-response tasks that were designed to investigate the role of different regions of the prefrontal cortex (PFC) during different working-memory component processes. From these data, we conclude that: (1) lateral PFC is anatomically organized according to the types of cognitive operations that one performs when attempting to temporarily maintain and manipulate information; and (2) consistent with the picture that has emerged from the monkey electrophysiological literature, human lateral PFC is involved in several encoding- and response-related processes as well as mnemonic and nonmnemonic processes that are engaged during the temporary maintenance of information. Thus, lateral PFC activity cannot be ascribed to the function of a single, unitary cognitive operation. [ABSTRACT FROM AUTHOR]

We investigated the activation of sensory and motor areas involved in the production of typing movements using functional magnetic resonance imaging (fMRI). Eleven experienced typists performed tasks, in which the spatial and temporal requirements as well as the number of digits involved were varied. These included a simple uni-digit repetitive task, a uni-digit sequential task, a dual-digit sequential task, a multi-digit sequential task, and typing text from memory. We found that the production of simple repetitive keypresses with the index finger primarily involved the activation of contralateral primary motor cortex (M1), although a small activation of the supplementary motor area (SMA) and other regions was sometimes observed as well. The sequencing of keypresses involved bilateral M1 and a stronger activation of the SMA and to a lesser extent the premotor area, cingulate gyrus, caudate, and lentiform nuclei. However, the activation of these areas did not exclusively depend on the complexity of the movements, since they were often activated during more simple movements, such as alternating two keypresses repeatedly. Somatosensory and parietal regions were also found to be activated during typing sequences. The activation of parietal areas did not exclusively depend on the spatial requirements of the task, since similar activation was observed during movements within intra-personal space (finger-thumb opposition) and may instead be related to the temporal requirements of the task. Our findings suggest that the assembly of well-learned, goal-directed finger movement sequences involves the SMA and other secondary motor areas as well as somatosensory and parietal areas. [ABSTRACT FROM AUTHOR]