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The cerebellum contributes to goal-directed navigation abilities and place coding in the hippocampus. Here we investigated its contribution to foraging strategies. We recorded hippocampal neurons in mice with impaired PKC-dependent cerebellar functions (L7-PKCI) and in their littermate controls while they performed a task where they were rewarded for visiting a subset of hidden locations. We found that L7-PKCI and control mice developed different foraging strategies: while control mice repeated spatial sequences to maximize their rewards, L7-PKCI mice persisted to use a random foraging strategy. Sequential foraging was associated with more place cells exhibiting theta-phase precession and theta rate modulation. Recording in the dark showed that PKC-dependent cerebellar functions controlled how self-motion cues contribute to the selectivity of place cells to both position and direction. Thus, the cerebellum contributes to the development of optimal sequential paths during foraging, possibly by controlling how self-motion and theta signals contribute to place cell coding., Competing Interests: The authors declare no competing interests., (© 2023 The Author(s).)

Cerebellar abnormalities have been reported in autism spectrum disorder (ASD). Beyond its role in hallmark features of ASD, the cerebellum and its connectivity with forebrain structures also play a role in navigation. However, the current understanding of navigation abilities in ASD is equivocal, as is the impact of the disorder on the functional anatomy of the cerebellum. In the present study, we investigated the navigation behavior of a population of ASD and typically developing (TD) adults related to their brain anatomy as assessed by structural and functional MRI at rest. We used the Starmaze task, which permits assessing and distinguishing two complex navigation behaviors, one based on allocentric learning and the other on egocentric learning of a route with multiple decision points. Compared to TD controls, individuals with ASD showed similar exploration, learning, and strategy performance and preference. In addition, there was no difference in the structural or functional anatomy of the cerebellar circuits involved in navigation between the two groups. The findings of our work suggest that navigation abilities, spatio-temporal memory, and their underlying circuits are preserved in individuals with ASD., (© 2022 The Authors. Autism Research published by International Society for Autism Research and Wiley Periodicals LLC.)

This review focuses on the functional and anatomical links between the cerebellum and the hippocampus and the role of their interplay in goal-directed navigation and spatial cognition. We will describe the interactions between the cerebellum and the hippocampus at different scales: a macroscopic scale revealing the joint activations of these two structures at the level of neuronal circuits, a mesoscopic scale highlighting the synchronization of neuronal oscillations, and finally a cellular scale where we will describe the activity of hippocampal neuronal assemblies following a targeted manipulation of the cerebellar system. We will take advantage of this framework to summarize the different anatomical pathways that may sustain this multiscale interaction. We will finally consider the possible influence of the cerebellum on pathologies traditionally associated with hippocampal dysfunction., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This article describes navigation data of 14 month-old APPPS1 and C57Bl6 in the Starmaze task. These data were acquired as positive controls of memory deficit in a model of the familial form of Alzheimers's disease (see Schmitt et al., Flexibility as a marker of early cognitive decline in humanized Apolipoprotein E ε4 (ApoE4) mice, Neurobiol Aging, 2021). They were acquired in a reduced version of the Starmaze environment and accompanied by a number of acquisitions in different control groups at 6 and 14 months to assess the robustness of the procedure and its associated memory scores. These data illustrate the extraction of a variety of navigation scores (including search strategy, spatial learning and memory) and provide a reference of navigation data in the Starmaze task for healthy 6-month-old controls, normal aging and a model of pathological memory deficit., Competing Interests: JS, PB and LA were full-time employees of Sanofi when this study was performed. The CNRS, LRR and her lab have financial interest in the sale of the Starmaze task. This work was supported by Sanofi (PB, JS, LA), the CNRS and Sorbonne University through UMR 8246 (LRR). The group of LRR is a member of the Labex BioPsy and ENP Foundation. This work also received support under the program Investissements d'Avenir launched by the French Government and implemented by the ANR, with the references ANR-10-LABX-BioPsy (LRR). Labex are supported by French State funds managed by the ANR within the Investissements d'Avenir program under reference ANR-11-IDEX-0004–02., (© 2021 The Author(s). Published by Elsevier Inc.)

To test the hypothesis that ApoE4 may be involved in cognitive deficits associated with aging, we investigated the impact of APOE4 status and aging on the flexibility and memory components of spatial learning in mice. Young adult (6 months) and middle-aged (14 months) ApoE4, ApoE3 and C57BL/6 male mice were tested for flexibility in an aquatic Y-maze, and for spatio-temporal memory acquisition in the Starmaze. Our results revealed a flexibility deficit of the 6-month-old ApoE4 mice compared to controls. However, this deficit was not associated with spatio-temporal memory deficit at the same age. Importantly, the ApoE4 flexibility deficit did not increase with age, nor turn into memory deficit, or was able to predict individual variations of memory performance at 14 months. By contrast, control ApoE3 mice showed a decline of flexibility at 14 months resulting in performance similar to that of ApoE4. Overall, our results suggest that ApoE4 could be associated with an acceleration of the flexibility decrease otherwise observed in normal aging., (Copyright © 2021. Published by Elsevier Inc.)

Background: The neuroanatomical bases of autism spectrum disorder remain largely unknown. Among the most widely discussed candidate endophenotypes, differences in cerebellar volume have been often reported as statistically significant., Methods: We aimed at objectifying this possible alteration by performing a systematic meta-analysis of the literature and an analysis of the ABIDE (Autism Brain Imaging Data Exchange) cohort. Our meta-analysis sought to determine a combined effect size of autism spectrum disorder diagnosis on different measures of the cerebellar anatomy as well as the effect of possible factors of variability across studies. We then analyzed the cerebellar volume of 328 patients and 353 control subjects from the ABIDE project., Results: The meta-analysis of the literature suggested a weak but significant association between autism spectrum disorder diagnosis and increased cerebellar volume (p = .049, uncorrected), but the analysis of ABIDE did not show any relationship. The studies meta-analyzed were generally underpowered; however, the number of statistically significant findings was larger than expected., Conclusions: Although we could not provide a conclusive explanation for this excess of significant findings, our analyses would suggest publication bias as a possible reason. Finally, age, sex, and IQ were important sources of cerebellar volume variability, although independent of autism diagnosis., (Copyright © 2017 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

How do we translate self-motion into goal-directed actions? Here we investigate the cognitive architecture underlying self-motion processing during exploration and goal-directed behaviour. The task, performed in an environment with limited and ambiguous external landmarks, constrained mice to use self-motion based information for sequence-based navigation. The post-behavioural analysis combined brain network characterization based on c-Fos imaging and graph theory analysis as well as computational modelling of the learning process. The study revealed a widespread network centred around the cerebral cortex and basal ganglia during the exploration phase, while a network dominated by hippocampal and cerebellar activity appeared to sustain sequence-based navigation. The learning process could be modelled by an algorithm combining memory of past actions and model-free reinforcement learning, which parameters pointed toward a central role of hippocampal and cerebellar structures for learning to translate self-motion into a sequence of goal-directed actions.

To examine the cerebellar contribution to human spatial navigation we used functional magnetic resonance imaging and virtual reality. Our findings show that the sensory-motor requirements of navigation induce activity in cerebellar lobules and cortical areas known to be involved in the motor loop and vestibular processing. By contrast, cognitive aspects of navigation mainly induce activity in a different cerebellar lobule (VIIA Crus I). Our results demonstrate a functional link between cerebellum and hippocampus in humans and identify specific functional circuits linking lobule VIIA Crus I of the cerebellum to medial parietal, medial prefrontal, and hippocampal cortices in nonmotor aspects of navigation. They further suggest that Crus I belongs to 2 nonmotor loops, involved in different strategies: place-based navigation is supported by coherent activity between left cerebellar lobule VIIA Crus I and medial parietal cortex along with right hippocampus activity, while sequence-based navigation is supported by coherent activity between right lobule VIIA Crus I, medial prefrontal cortex, and left hippocampus. These results highlight the prominent role of the human cerebellum in both motor and cognitive aspects of navigation, and specify the cortico-cerebellar circuits by which it acts depending on the requirements of the task., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The cerebellum has already been shown to participate in the navigation function. We propose here that this structure is involved in maintaining a sense of direction and location during self-motion by monitoring sensory information and interacting with navigation circuits to update the mental representation of space. To better understand the processing performed by the cerebellum in the navigation function, we have reviewed: the anatomical pathways that convey self-motion information to the cerebellum; the computational algorithm(s) thought to be performed by the cerebellum from these multi-source inputs; the cerebellar outputs directed toward navigation circuits and the influence of self-motion information on space-modulated cells receiving cerebellar outputs. This review highlights that the cerebellum is adequately wired to combine the diversity of sensory signals to be monitored during self-motion and fuel the navigation circuits. The direct anatomical projections of the cerebellum toward the head-direction cell system and the parietal cortex make those structures possible relays of the cerebellum influence on the hippocampal spatial map. We describe computational models of the cerebellar function showing that the cerebellum can filter out the components of the sensory signals that are predictable, and provides a novelty output. We finally speculate that this novelty output is taken into account by the navigation structures, which implement an update over time of position and stabilize perception during navigation.

Electrophysiological oscillations in different frequency bands co-occur with perceptual, motor and cognitive processes but their function and respective contributions to these processes need further investigations. Here, we recorded MEG signals and seek for percept related modulations of alpha, beta and gamma band activity during a perceptual form/motion integration task. Participants reported their bound or unbound perception of ambiguously moving displays that could either be seen as a whole square-like shape moving along a Lissajou's figure (bound percept) or as pairs of bars oscillating independently along cardinal axes (unbound percept). We found that beta (15-25 Hz), but not gamma (55-85 Hz) oscillations, index perceptual states at the individual and group level. The gamma band activity found in the occipital lobe, although significantly higher during visual stimulation than during base line, is similar in all perceptual states. Similarly, decreased alpha activity during visual stimulation is not different for the different percepts. Trial-by-trial classification of perceptual reports based on beta band oscillations was significant in most observers, further supporting the view that modulation of beta power reliably index perceptual integration of form/motion stimuli, even at the individual level.

Waves of activity following a focal stimulation are reliably observed to spread across the cortical tissue. The origin of these waves remains unclear and the underlying mechanisms and function are still debated. In this study, we ask whether waves of activity modulate the magnetoencephalography (MEG) signals recorded in humans during visual stimulation with Gabor patches sequentially flashed along a vertical path, eliciting a perception of vertical apparent motion. Building upon the functional properties of long-rang horizontal connections, proposed to contribute to spreading activity, we specifically probe the amplitude and latency of MEG responses as a function of Gabor contrast and orientation. The results indicate that in the left hemisphere the response amplitude is enhanced and the half height response latency is shortened for co-aligned Gabor as compared to misaligned Gabor patches at a low but not at a high contrast. Building upon these findings, we develop a biologically plausible computational model that performs a "spike time alignment" of the responses to elongated contours with varying contrast, endowing them with a phase advance relative to misaligned contours.

There is converging evidence that electrophysiological responses over posterior cortical regions in the 200-300 ms range distinguish between physically identical stimuli that reach consciousness or remain unseen. Here, we attempt at determining the sources of this awareness-related activity using magneto-encephalographic (MEG). Fourteen subjects were presented with faint colored gratings at threshold for contrast and reported on each trial whether the grating was seen or unseen. Subjects were primed with a color cue that could be congruent or incongruent with the color of the grating, to probe to what extent two co-localized features (color and orientation) would be bound in consciousness. The contrast between neural responses to seen and unseen physically identical gratings revealed a sustained posterior difference between 190 and 350 ms, thereby replicating prior studies. We further show that the main sources of the awareness-related activity were localized bilaterally on the lateral convexity of the occipito-temporal region, in the Lateral Occipital (LO) complex, as well as in the right posterior infero-temporal region. No activity differentiating seen and unseen trials could be observed in frontal or parietal regions in this latency range, even at lower threshold. Color congruency did not improve grating's detection, and the awareness-related activity was independent from color congruency. However, at the neural level, color congruency was processed differently in grating-present and grating-absent trials. The pattern of results suggests the existence of a neural process of color congruency engaging left parietal regions that is affected by the mere presence of another feature, whether this feature reaches consciousness or not. Altogether, our results reveal an occipital source of visual awareness insensitive to color congruency, and a simultaneous parietal source not engaged in visual awareness, but sensitive to the manipulation of co-localized features.

Visual shape and motion information, processed in distinct brain regions, should be combined to elicit a unitary coherent percept of an object in motion. In an fMRI study, we identified brain regions underlying the perceptual binding of motion and shape independently of the features-contrast, motion, and shape-used to design the moving displays. These displays alternately elicited a bound (moving diamond) or an unbound (disconnected moving segments) percept, and were either physically unchanging yet perceptually bistable or physically changing over time. The joint analysis of the blood-oxygen-level-dependent (BOLD) signals recorded during bound or unbound perception with these different stimuli revealed a network comprising the occipital lobe and ventral and dorsal visual regions. Bound percepts correlated with in-phase BOLD increases within the occipital lobe and a ventral area and decreased activity in a dorsal area, while unbound percepts elicited moderate BOLD modulations in these regions. This network was similarly activated by bistable unchanging displays and by displays periodically changing over time. The uncovered interplay between the two regions is proposed to reflect a generic binding process that dynamically weights the perceptual evidence supporting the different shape and motion interpretations according to the reliability of the neural activity in these regions.

This study investigates neural magneto-encephalographic (MEG) correlates of visual form and motion binding. Steady-state visual evoked fields (SSVEF) were recorded in MEG while observers reported their bound or unbound perception of moving bars arranged in a square shape. By using pairs of oscillating vertical and horizontal bars, "frequency-tagged" at f1 and f2, we identified a region with enhanced sustained power at 2f1+2f2 intermodulation frequency correlated with perceptual reports. Intermodulation power is more important during perceptual form/motion integration than during the perceptual segmentation of the stimulus into individual component motions, indicating that intermodulation frequency power is a neuromarker of form/motion integration. Source reconstruction of cortical activities at the relevant frequencies further reveals well segregated activity in the occipital lobe at the fundamental of the stimulation, f1 and f2, widely spread activity at 2f1 and 2f2 and a focal activity in the medial part of the right precentral sulcus region at the intermodulation component, 2f1+2f2. The present findings indicate that motion tagging provides a powerful way of investigating the processes underlying visual form/motion binding non-invasively in humans., (Copyright © 2011. Published by Elsevier B.V.)

This study explores the extent to which a display changing periodically in perceptual interpretation through smooth periodic physical changes-an inducer-is able to elicit perceptual switches in an intrinsically bistable distant probe display. Four experiments are designed to examine the coupling strength and bistable dynamics with displays of varying degree of ambiguity, similarity, and symmetry-in motion characteristics-as a function of their locations in visual space. The results show that periodic fluctuations of a remote inducer influence a bistable probe and regulate its dynamics through coupling. Coupling strength mainly depends on the relative locations of the probe display and the contextual inducer in the visual field, with stronger coupling when both displays are symmetrical around the vertical meridian and weaker coupling otherwise. Smaller effects of common fate and symmetry are also found. Altogether, the results suggest that long-range interhemispheric connections, presumably involving the corpus callosum, are able to synchronize perceptual transitions across the vertical meridian. If true, bistable dynamics may provide a behavioral method to probe interhemispheric connectivity in behaving human. Consequences of these findings for studies using stimuli symmetrical around the vertical meridian are evaluated.

This study uses a rapid-serial-visual-presentation (RSVP) paradigm to test the extent to which shape and motion direction can be independently accessed and processed during the perception of structure-from-motion (SFM) stimuli. Subjects reported the number of occurrences of shape or motion direction during RSVP sequences of 3D-SFM stimuli. Overall, performance was better for motion than shape. In the motion task, observers were less accurate when the motion direction was repeated revealing a repetition blindness (RB) effect. In addition, the repetition of shape, although irrelevant to the motion task, resulted in increased performance, without change in RB rate. In contrast, there was no RB at the group level in the shape task and the repetition of the irrelevant motion direction had no effect on the performance. A closer look at the data showed that observers fall in two statistically distinct groups for the shape task. Some observers (N = 6) show a repetition advantage (RA) while the others (N = 5) show a repetition blindness (RB) effect. No behavioral differences between groups could be found for the motion task. The implications of these results for models of SFM processing are discussed in the light of the type/token theory (N. Kanwisher, 2001).

This study aims at segregating the neural substrate for the 3D-form and 3D-motion attributes in structure-from-motion perception, and at disentangling the stimulus-driven and endogenous-attention-driven processing of these attributes. Attention and stimulus were manipulated independently: participants had to detect the transitions of one attribute--form, 3D motion or colour--while the visual stimulus underwent successive transitions of all attributes. We compared the BOLD activity related to form and 3D motion in three conditions: stimulus-driven processing (unattended transitions), endogenous attentional selection (task) or both stimulus-driven processing and attentional selection (attended transitions). In all conditions, the form versus 3D-motion contrasts revealed a clear dorsal/ventral segregation. However, while the form-related activity is consistent with previously described shape-selective areas, the activity related to 3D motion does not encompass the usual "visual motion" areas, but rather corresponds to a high-level motion system, including IPL and STS areas. Second, we found a dissociation between the neural processing of unattended attributes and that involved in endogenous attentional selection. Areas selective for 3D-motion and form showed either increased activity at transitions of these respective attributes or decreased activity when subjects' attention was directed to a competing attribute. We propose that both facilitatory and suppressive mechanisms of attribute selection are involved depending on the conditions driving this selection. Therefore, attentional selection is not limited to an increased activity in areas processing stimulus properties, and may unveil different functional localization from stimulus modulation.

Functional magnetic resonance imaging was used to compare the neural correlates of three different types of spatial coding, which are implicated in crucial cognitive functions of our everyday life, such as visuomotor coordination and orientation in topographical space. By manipulating the requested spatial reference during a task of relative distance estimation, we directly compared viewer-centered, object-centered, and landmark-centered spatial coding of the same realistic 3-D information. Common activation was found in bilateral parietal, occipital, and right frontal premotor regions. The retrosplenial and ventromedial occipital-temporal cortex (and parts of the parietal and occipital cortex) were significantly more activated during the landmark-centered condition. The ventrolateral occipital-temporal cortex was particularly involved in object-centered coding. Results strongly demonstrate that viewer-centered (egocentric) coding is restricted to the dorsal stream and connected frontal regions, whereas a coding centered on external references requires both dorsal and ventral regions, depending on the reference being a movable object or a landmark.

The brain plays a central role in sexual motivation. To identify cerebral areas whose activation was correlated with sexual desire, eight healthy male volunteers were studied with functional magnetic resonance imaging (fMRI). Visual stimuli were sexually stimulating photographs (S condition) and emotionally neutral photographs (N condition). Subjective responses pertaining to sexual desire were recorded after each condition. To image the entire brain, separate runs focused on the upper and the lower parts of the brain. Statistical Parametric Mapping was used for data analysis. Subjective ratings confirmed that sexual pictures effectively induced sexual arousal. In the S condition compared to the N condition, a group analysis conducted on the upper part of the brain demonstrated an increased signal in the parietal lobes (superior parietal lobules, left intraparietal sulcus, left inferior parietal lobule, and right postcentral gyrus), the right parietooccipital sulcus, the left superior occipital gyrus, and the precentral gyri. In addition, a decreased signal was recorded in the right posterior cingulate gyrus and the left precuneus. In individual analyses conducted on the lower part of the brain, an increased signal was found in the right and/or left middle occipital gyrus in seven subjects, and in the right and/or left fusiform gyrus in six subjects. In conclusion, fMRI allows to identify brain responses to visual sexual stimuli. Among activated regions in the S condition, parietal areas are known to be involved in attentional processes directed toward motivationally relevant stimuli, while frontal premotor areas have been implicated in motor preparation and motor imagery. Further work is needed to identify those specific features of the neural responses that distinguish sexual desire from other emotional and motivational states.

Many event-related functional magnetic resonance imaging paradigms performed so far have been designed to study a limited part of the brain with high temporal resolution. However, event-related paradigms can be exploratory, therefore requiring whole brain scans and so repetition times (TR) of several seconds. For these large TR values, the slice acquisition order may have an important effect on the detection of event-related activation. Indeed, when the scanning is interleaved, the temporal delay between the acquisition of two contiguous slices can reach a few seconds. During this time, the subject is likely to move, and the haemodynamic response will vary significantly. In this case, the interpolation applied between contiguous slices for motion correction induces a temporal smoothing between voxels that are spatially close but temporally sampled a few seconds apart. This should modify the frequency structure of the response and may impair the detection of short events. We, therefore tested the effect of three acquisition schemes (sequential, sequential with gap and interleaved, INT) at two repetition times (TR=3 and 6 s on six and seven subjects, respectively) on activation detection and frequency content in a visual motion event-related paradigm. Unexpectedly, for large TR (6 s), results were found in favour of the INT acquisition scheme (P<0.05). For smaller TR, no strong bias could be found. Generally, intra-subject variability (across acquisition schemes) is found to be much smaller than inter-subject variability, confirming the importance of multi-subjects analyses. Our study also shows that important physiological information is carried by high frequency components that should not be filtered out.

A methodology for fMRI data analysis confined to the cortex, Cortical Surface Mapping (CSM), is presented. CSM retains the flexibility of the General Linear Model based estimation, but the procedures involved are adapted to operate on the cortical surface, while avoiding to resort to explicit flattening. The methodology is tested by means of simulations and application to a real fMRI protocol. The results are compared with those obtained with a standard, volume-oriented approach (SPM), and it is shown that CSM leads to local differences in sensitivity, with generally higher sensitivity for CSM in two of the three subjects studied. The discussion provided is focused on the benefits of the introduction of anatomical information in fMRI data analysis, and the relevance of CSM as a step toward this goal.

Functional magnetic resonance imaging was used to study the cortical bases of 3-D structure perception from visual motion in human. Nine subjects underwent three experiments designed to locate the areas involved in (i) motion processing (random motion versus static dots), (ii) coherent motion processing (expansion/ contraction versus random motion) and (iii) 3-D shape from motion reconstruction (3-D surface oscillating in depth versus random motion). Two control experiments tested the specific influence of speed distribution and surface curvature on the activation results. All stimuli consisted of random dots so that motion parallax was the only cue available for 3-D shape perception. As expected, random motion compared with static dots induced strong activity in areas V1/V2, V5+ and the superior occipital gyrus (SOG; presumptive V3/V3A). V1/V2 and V5+ showed no activity increase when comparing coherent motion (expansion or 3-D surface) with random motion. Conversely, V3/V3A and the dorsal parieto-occipital junction were highlighted in both comparisons and showed gradually increased activity for random motion, coherent motion and a curved surface rotating in depth, which suggests their involvement in the coding of 3-D shape from motion. Also, the ventral aspect of the left occipito-temporal junction was found to be equally responsive to random and coherent motion stimuli, but showed a specific sensitivity to curved 3-D surfaces compared with plane surfaces. As this region is already known to be involved in the coding of static object shape, our results suggest that it might integrate various cues for the perception of 3-D shape.

Although it is largely accepted that visual-mental imagery and perception draw on many of the same neural structures, the existence and nature of neural processing in the primary visual cortex (or area V1) during visual imagery remains controversial. We tested two general hypotheses: The first was that V1 is activated only when images with many details are formed and used, and the second was that V1 is activated whenever images are formed, even if they are not necessarily used to perform a task. We used event-related functional magnetic resonance imaging (ER-fMRI) to detect and characterize the activity in the calcarine sulcus (which contains the primary visual cortex) during single instances of mental imagery. The results revealed reproducible transient activity in this area whenever participants generated or evaluated a mental image. This transient activity was strongly enhanced when participants evaluated characteristics of objects, whether or not details actually needed to be extracted from the image to perform the task. These results show that visual imagery processing commonly involves the earliest stages of the visual system.

In this note we draw attention to a source of potential ambiguity in functional neuroimaging results when data analysis is based on the resolution of a linear model. This ambiguity arises whenever there exists correlation between the model covariates. A single-subject PET activation experiment helps to illustrate to what extent correlation can affect statistical results interpretation, possibly leading to misinterpretation of part of the activation pattern. This note is intended to clarify this point and to suggest the use of a simple and well-known procedure to deal with these situations. In the Appendix, we suggest a convenient mathematical formulation for statistical tests particularly useful in such cases., (Copyright 1999 Academic Press.)

The present study aimed at determining the distribution and somatotopical organization of striatal activation during performance of simple motor tasks. Ten right-handed healthy volunteers were studied by using a 3-T whole-body magnetic resonance unit and echo planar imaging. The tasks consisted of self-paced flexion/extension of the right fingers or toes. Motor activation was found mainly in the putamen posterior to the anterior commissure (10 of 10 subjects) and the globus pallidus (6 subjects), whereas the caudate nucleus was activated in only 3 subjects, and in a smaller area. Thus, performance of a simple motor task activated the sensorimotor territory of the basal ganglia. Within the putamen, there was a somatotopical organization of the foot and hand areas similar to that observed in nonhuman primates. These data suggest that functional magnetic resonance imaging can be used to study normal function of the basal ganglia and should therefore also allow investigation of patients with movement disorders.

In BOLD fMRI a detailed analysis of the MRI signal time course sometimes shows time differences between different activated regions. Some researchers have suggested that these latencies could be used to infer the temporal order of activation of these cortical regions. Several effects must be considered, however, before interpreting these latencies. The effect of a slice-dependent time shift (SDTS) with multi-slice acquisitions, for instance, may be important for regions located on different slices. After correction for this SDTS effect the time dispersion between activated regions is significantly decreased and the correlation between the MRI signal time course and the stimulation paradigm is improved. Another effect to consider is the latency which may exist between perception and stimulus presentation. It is shown that the control of perception can be achieved using a finger-spanning technique during the fMRI acquisition. The use of this perception profile rather than an arbitrary waveform derived from the paradigm proves to be a powerful alternative to fMRI data processing, especially with chemical senses studies, when return to baseline is not always correlated to stimulus suppression. This approach should also be relevant to other kinds of stimulation tasks, as a realistic way of monitoring the actual task performance, which may depend on attention, adaptation, fatigue or even variability of stimulus presentation.