Distinguishable brain activation networks for short- and long-term motor skill learning

The acquisition of a new motor skill is characterized first by a short-term, fast learning stage in which performance improves rapidly, and subsequently by a long-term, slower learning stage in which additional performance gains are incremental. Previous functional imaging studies have suggested that distinct brain networks mediate these two stages of learning, but direct comparisons using the same task have not been performed. Here we used a task in which subjects learn to track a continuous 8-s sequence demanding variable isometric force development between the fingers and thumb of the dominant, right hand. Learning-associated changes in brain activation were characterized using functional MRI (fMRI) during short-term learning of a novel sequence, during short-term learning after prior, brief exposure to the sequence, and over long-term (3 wk) training in the task. Short-term learning was associated with decreases in activity in the dorsolateral prefrontal, anterior cingulate, posterior parietal, primary motor, and cerebellar cortex, and with increased activation in the right cerebellar dentate nucleus, the left putamen, and left thalamus. Prefrontal, parietal, and cerebellar cortical changes were not apparent with short-term learning after prior exposure to the sequence. With long-term learning, increases in activity were found in the left primary somatosensory and motor cortex and in the right putamen. Our observations extend previous work suggesting that distinguishable networks are recruited during the different phases of motor learning. While short-term motor skill learning seems associated primarily with activation in a cortical network specific for the learned movements, long-term learning involves increased activation of a bihemispheric cortical-subcortical network in a pattern suggesting "plastic" development of new representations for both motor output and somatosensory afferent information.     

How is a motor skill learned? Change and invariance at the levels of task success and trajectory control

The public pays large sums of money to watch skilled motor performance. Notably, however, in recent decades motor skill learning (performance improvement beyond baseline levels) has received less experimental attention than motor adaptation (return to baseline performance in the setting of an external perturbation). Motor skill can be assessed at the levels of task success and movement quality, but the link between these levels remains poorly understood. We devised a motor skill task that required visually guided curved movements of the wrist without a perturbation, and we defined skill learning at the task level as a change in the speed-accuracy trade-off function (SAF). Practice in restricted speed ranges led to a global shift of the SAF. We asked how the SAF shift maps onto changes in trajectory kinematics, to establish a link between task-level performance and fine motor control. Although there were small changes in mean trajectory, improved performance largely consisted of reduction in trial-to-trial variability and increase in movement smoothness. We found evidence for improved feedback control, which could explain the reduction in variability but does not preclude other explanations such as an increased signal-to-noise ratio in cortical representations. Interestingly, submovement structure remained learning invariant. The global generalization of the SAF across a wide range of difficulty suggests that skill for this task is represented in a temporally scalable network. We propose that motor skill acquisition can be characterized as a slow reduction in movement variability, which is distinct from faster model-based learning that reduces systematic error in adaptation paradigms.     

Motor learning after stroke: Is skill acquisition a prerequisite for contralesional neuroplastic change?

Limited data directly characterize the dynamic evolution of brain activity associated with motor learning after stroke. The current study considered whether sequence-specific motor skill learning or increasing non-specific use of the hemiparetic upper extremity drive functional reorganization of the contralesional motor cortex after stroke. Eighteen individuals with chronic middle cerebral artery stroke practiced one of two novel motor tasks; a retention test occurred on a separate fifth day. Using the hemiparetic arm, participants performed a serial targeting task during two functional MRI scans (day one and retention). Participants were randomized into either a task-specific group, who completed three additional sessions of serial targeting practice, or a general arm use group, who underwent three training sessions of increased but non-task specific use of the hemiparetic arm. Both groups performed a repeated sequence of responses that may be learned, and random sequences of movement, which cannot be learned. Change in reaction and movement time for the repeated sequence indexed motor learning; shifts in the laterality index (LI) within primary motor cortex (M1) for repeated and random sequences illustrated training effects on brain activity. Task-specific practice of the repeated sequence facilitated motor learning and shifted the LI for M1 as shown by a reduced volume of contralesional cortical activity. Random sequence performance did not stimulate motor learning or alter the LI within the task-specific training group. Further, between-group comparisons showed that increasing general arm use did not induce motor learning or alter brain activity for either random or repeated sequences. Motor skill learning of a repeated sequence altered cortical activation by inducing a more normal, contralateral pattern of brain activation. Our data suggest that task-specific motor learning may be an important stimulant for neuroplastic change and can remediate maladaptive patterns of brain activity after stroke.     

Aberrant brain activation following motor skill learning in schizophrenic patients as shown by functional magnetic resonance imaging

BACKGROUND: Motor skill learning may be impaired in schizophrenia. While functional brain imaging studies have shown reduced activation during motor task performance in schizophrenic patients, brain activity changes with motor skill learning in these patients have not been studied by functional imaging. METHODS: A sequential complex motor task involving the right hand was performed by nine medicated schizophrenic patients and 10 age-matched healthy controls. Functional magnetic resonance images were obtained using a gradient echo, echoplanar imaging (EPI) pulse sequence before and after 1 week of training in performing the task. RESULTS: Bilaterally, patients showed significantly less blood oxygenation level-dependent (BOLD) signal response in the premotor area (PMA) before beginning motor training than controls. BOLD signal response increased in the left PMA of schizophrenic patients after 1 week of motor training; in contrast, the signal decreased in the left PMA of control subjects. Training effects concerning the number of finger movement sequences achieved did not differ between groups. Daily neuroleptic dose did not significantly affect changes with training in BOLD signal response in the PMA. CONCLUSIONS: These preliminary results suggest that schizophrenic patients have dysfunction of neural networks in areas including the PMA that are involved in executing a complex motor task. In terms of brain activity, motor learning may be less efficient or slower in the patients than in healthy subjects.     

Adaptive Plasticity in Primate Motor Cortex as a Consequence of Behavioral Experience and Neuronal Injury

It is now clear that the motor cortex of adult mammals is capable of widespread functional reorganization. After specific types of motor skill training, the cortical representations of the movements used to perform the task expand, invading adjacent motor representations. After peripheral nerve injury, representations of unaffected muscles expand, invading those of the denervated muscles. After focal cortical injury, representations in the uninjured, adjacent cortical tissue undergo widespread alterations. Specific changes are dependent upon the use of the affected limb during the postinjury period. It now appears likely that motor map alterability results from changes in synaptic efficacy of intrinsic horizontal connections within motor cortex. Taken together, these studies suggest that the neurophysiological circuitry underlying muscle and movement maps within primary motor cortex is continually remodeled throughout an individual's life. The functional organization of motor cortex is constantly reshaped by behavioral demands for the learning of new motor skills.     

Strengthening of horizontal cortical connections following skill learning

Learning a new motor skill requires an alteration in the spatiotemporal pattern of muscle activation. Motor areas of cerebral neocortex are thought to be involved in this type of learning, possibly by functional reorganization of cortical connections. Here we show that skill learning is accompanied by changes in the strength of connections within adult rat primary motor cortex (M1). Rats were trained for three or five days in a skilled reaching task with one forelimb, after which slices of motor cortex were examined to determine the effect of training on the strength of horizontal intracortical connections in layer II/III. The amplitude of field potentials in the forelimb region contralateral to the trained limb was significantly increased relative to the opposite 'untrained' hemisphere. No differences were seen in the hindlimb region. Moreover, the amount of long-term potentiation (LTP) that could be induced in trained M1 was less than in controls, suggesting that the effect of training was at least partly due to LTP-like mechanisms. These data represent the first direct evidence that plasticity of intracortical connections is associated with learning a new motor skill.     

Identification of cortical activation and white matter architecture according to short-term motor learning in the human brain: functional MRI and diffusion tensor tractography study

Objectives

The purpose of this study was to examine whether two weeks of short-term motor training led to changes of cortical activation patterns and white matter integrity in cortical and subcortical structures according to motor skill acquisition, using functional MRI (fMRI) and diffusion tensor image (DTI).

Methods

We enrolled twenty healthy volunteers, who were randomly assigned to training and control groups. The training group was trained with a serial reaction time (SRT) task, one hour a day for 10 days within two weeks, whereas the control group had no training. Movement accuracy (MA) and movement time (MT) were tested twice before and after training, while fMRI was scanned during SRT task. Immediately after these tests, DTI was conducted.

Results

The training group showed significant differences in the increase of MA and the reduction of MT, compared with control group. The activated volume of cortices related to motor function was gradually decreased in the training group, according to motor skill acquisition. DTI analysis showed no significant differences between pre- and post-tests in both groups.

Conclusions

Our findings indicated that short-term motor training led to cortical activation patterns of the cerebral cortex according to implicit motor learning. However, changes of white matter integrity were not observed. It seems that short-term motor training may not be enough to change white matter architectures, due to lack of the training period.     

Neuroanatomical correlates of motor acquisition and motor transfer

The acquisition of new motor skills is dependent on task practice. In the case of motor transfer, learning can be facilitated by prior practice of a similar skill. Although a multitude of studies have investigated the brain regions contributing to skill acquisition, the neural bases associated with the savings seen at transfer have yet to be determined. In the current study, we used functional MRI to examine how brain activation differs during acquisition and transfer of a visuomotor adaptation task. Two groups of participants adapted manual aiming movements to three different rotations of the feedback display in a sequential fashion, with a return to baseline display conditions between each rotation. Subjects showed a savings in the rate of adaptation when they had prior adaptive experiences (i.e., positive transfer of learning). This savings was associated with a reduction in activity of brain regions typically recruited early in the adaptation process, including the right inferior frontal gyrus, primary motor cortex, inferior temporal gyrus, and the cerebellum (medial HIII). Moreover, although these regions exhibit activation that is correlated across subjects with the rate of acquisition, the degree of savings at transfer was correlated with activity in the right cingulate gyrus, left superior parietal lobule, right inferior parietal lobule, left middle occipital gyrus, and bilaterally in the cerebellum (HV/VI). The cerebellar activation was in the regions surrounding the posterior superior fissure, which is thought to be the site of storage for acquired internal models. Thus we found that motor transfer is associated with brain activation that typically characterizes late learning and storage. Transfer seems to involve retrieval of a previously formed motor memory, allowing the learner to move more quickly through the early stage of learning.     

Levodopa-sensitive, dynamic changes in effective connectivity during simultaneous movements in Parkinson's disease

Changes in effective connectivity during the performance of a motor task appear important for the pathogenesis of motor symptoms in Parkinson's disease (PD). One type of task that is typically difficult for individuals with PD is simultaneous or bimanual movement, and here we investigate the changes in effective connectivity as a potential mechanism. Eight PD subjects off and on l-DOPA medication and 10 age-matched healthy control subjects performed both simultaneous and unimanual motor tasks in an fMRI scanner. Changes in effective connectivity between regions of interest (ROIs) during simultaneous and unimanual task performance were determined with structural equation modeling (SEM), and changes in the temporal dynamics of task performance were determined with multivariate autoregressive modeling (MAR). PD subjects demonstrated alterations in both effective connectivity and temporal dynamics compared with control subjects during the performance of a simultaneous task. l-DOPA treatment was able to partially normalize effective connectivity and temporal patterns of activity in PD, although some connections remained altered in PD even after medication. Our results suggest that difficulty performing simultaneous movements in PD is at least in part mediated by a disruption of effective communication between widespread cortical and subcortical areas, and l-DOPA assists in normalizing this disruption. These results suggest that even when the site of neurodegeneration is relatively localized, study of how disruption in a single region affects connectivity throughout the brain can lead to important advances in the understanding of the functional deficits caused by neurodegenerative disease.     

Transcranial magnetic stimulation and the motor learning-associated cortical plasticity

It has been well established that repetitive motor performance and skill learning alter the functional organization of human corticomotoneuronal system. Over the past decade, transcranial magnetic stimulation (TMS) has helped to demonstrate motor practice and learning-related changes in corticomotoneuronal excitability and representational plasticity. It has also provided some insights into the mechanisms underlying such plasticity. TMS-derived indices show that motor practice, skill acquisition and learning are associated with an increase in cortical excitability and a modulation of intracortical inhibition partly related to the amount of GABA-related inhibition. It has been suggested that these changes in excitability might be related to learning and motor memory formation in the motor cortex. However, it has proved difficult to relate different aspects of TMS-derived representational plasticity with specific behavioral outcomes. A better understanding of the relationship between TMS measurements of practice-related cortical plasticity and underlying mechanisms, in the context of associated changes in behavior, will facilitate the development of techniques and protocols that will allow predictable modulation of cortical plasticity in health and disease.     

Skilled motor learning does not enhance long-term depression in the motor cortex in vivo

Learning of motor skills may occur as a consequence of changes in the efficacy of synaptic connections in the primary motor cortex. We investigated if learning in a reaching task affects the excitability, short-term plasticity, and long-term plasticity of horizontal connections in layers II-III of the motor cortex. Because training in this task requires animals to be food-deprived, we compared the trained animals with similarly food-deprived untrained animals and normal controls. The results show that the excitability, short-term plasticity, and long-term plasticity of the studied horizontal connections were unaffected by motor learning. However, stress-related effects produced by food deprivation and handling significantly enhanced the expression of long-term depression in these pathways. These results are compatible with the hypothesis that the acquisition of a complex motor skill produces bi-directional changes in synaptic strength that are distributed throughout the complex neural networks of motor cortex, which remains synaptically balanced during learning. The results are incompatible with the idea that learning causes large unidirectional changes in the population response of these neural networks, which may occur instead during certain behavioral states, such as stress.     

Motor sequence learning with the nondominant left hand

Whereas the human right hemisphere is active during execution of contralateral hand movements, the left hemisphere is engaged for both contra- and ipsilateral movements, at least for right-handed subjects. Whether this asymmetry is also found during motor learning remains unknown. Implicit sequence learning by the nondominant left hand was examined with the serial reaction time (SRT) task during functional brain imaging. As learning progressed, increases in brain activity were observed in left lateral premotor cortex (PMC) and bilaterally in supplementary motor areas (SMA), with the increase significantly greater in the left hemisphere. The left SMA site was similar to one previously identified with right-hand learning, suggesting that this region is critical for representing a sequence independent of effector. Learning with the left hand also recruited a widespread set of temporal and frontal regions, suggesting that motor skill learning with the nondominant hand develops within both cognitive and motor-related functional networks. After skill acquisition, subjects performed the SRT task with their right hands, and sequence transfer was tested with the original and a mirror-ordered sequence. With the original sequence, the stimulus sequence and series of response locations remained unchanged, but the finger movements were different. With the mirror-ordered sequence, the response sequence involved finger movements homologous to those used during training. Performance of the original and mirror sequence by the right hand was significantly better than with random stimuli. Mirror transformation of the sequence by the right hand was associated with a marked increase in regional activity in the left motor cortex, consistent with a role for sequential transformation at this level of the motor output pathway.     

Similar network activated by young and old adults during the acquisition of a motor sequence

In this functional MRI (fMRI) study, we investigated ageing effects on motor skill learning. We applied an adapted version of the serial reaction time (SRT) task to extensive groups of young (N=26) and elderly (N=40) subjects. Since indications have been provided for age-related shrinkage of brain regions assumed to be critical to motor skill learning, we tested the hypothesis that age effects on implicit sequence learning are larger on a neurofunctional level than on a behavioural level. The SRT task consisted of two identical scan sessions, in which subjects had to manually trail an asterisk appearing serially in one of four spatial positions by means of button-pressing. Reliable response time reductions were already found in the first session for both the young and the elderly groups, when comparing a fixed sequence condition to a random sequence, but the learning effect was greater for the young subjects. In the second session, though, both groups showed a similar degree of learning. This indicates that implicit sequence learning is still intact in elderly adults, but that the rate of learning is somewhat slower. Reliable learning-related changes in brain activity were also observed. A similar network of brain regions was recruited by both groups during the fixed compared to the random sequence, involving several regions that have been previously associated with implicit sequence learning, including bilateral parietal, and frontal regions, the supplementary motor area (SMA), cerebellum and the basal ganglia. The direct group comparison did not reveal any differences in brain activity. In addition, we did not observe any significant differences in activity when comparing the different sessions either, neither for the young nor for the elderly subjects. Hence, we did not find indications for an age-related functional reorganisation of neural networks involved in motor sequence learning. In view of earlier reports of pronounced ageing effects on the performance on declarative memory tasks, our finding of age-related sparing of processes that sustain motor skill learning, provides further support for the proposition of different memory systems relying on different brain substrates.     

Time course and temporal order of changes in movement kinematics during learning of fast and accurate elbow flexions

Learning of a motor task, such as making accurate goal-directed movements, is associated with a number of changes in limb kinematics and in the EMG activity that produces the movement. Some of these changes include increases in movement velocity, improvements in end-point accuracy, and the development of a biphasic/triphasic EMG pattern for fast movements. One question that has remained unanswered is whether the time course of the learning-related changes in movement parameters is similar for all parameters. The present paper focuses on this question and presents evidence that different parameters evolve with a specific temporal order. Neurologically normal subjects were trained to make horizontal, planar movements of the elbow that were both fast and accurate. The performance of the subjects was monitored over the course of 400 movements made during experiments lasting approximately 1.5 h. We measured time-related parameters (duration of acceleration, duration of deceleration, and movement duration) and amplitude-related parameters (peak acceleration, peak deceleration, peak velocity), as well as movement distance. In addition, each subject’s reaction time and EMG activity was monitored. We found that reaction time was the parameter that changed the fastest and that reached a steady baseline earliest. Time-related parameters decreased at a somewhat slower rate and plateaued next. Amplitude-related parameters were slowest in reaching steady-state values. In subjects making the fastest movements, a triphasic EMG patterns was observed to develop. Our findings reveal that movement parameters change with different time courses during the process of motor learning. The results are discussed in terms of the neural substrates that may be responsible for the differences in this aspect of motor learning and skill acquisition. Received: 28 December 1998 / Accepted: 22 June 1999     

Medial frontal negativities predict performance improvements during motor sequence but not motor adaptation learning

Alterations in our environment require us to learn or alter motor skills to remain efficient. Also, damage or injury may require the relearning of motor skills. Two types have been identified: movement adaptation and motor sequence learning. Doyon et al. (2003, Distinct contribution of the cortico‐striatal and cortico‐cerebellar systems to motor skill learning. Neuropsychologia, 41(3), 252‐262) proposed a model to explain the neural mechanisms related to adaptation (cortico‐cerebellar) and motor sequence learning (cortico‐striatum) tasks. We hypothesized that medial frontal negativities (MFNs), event‐related electrocortical responses including the error‐related negativity (ERN) and correct‐response‐related negativity (CRN), would be trait biomarkers for skill in motor sequence learning due to their relationship with striatal neural generators in a network involving the anterior cingulate and possibly the supplementary motor area. We examined 36 participants' improvement in a motor adaptation and a motor sequence learning task and measured MFNs elicited in a separate Spatial Stroop (conflict) task. We found both ERN and CRN strongly predicted performance improvement in the sequential motor task but not in the adaptation task, supporting this aspect of the Doyon model. Interestingly, the CRN accounted for additional unique variance over the variance shared with the ERN suggesting an expansion of the model.     

Combined visual attention and finger movement effects on human brain representations

Sensory and motor systems interact in complex ways; visual attention modifies behavior, neural encoding, and brain activation; and dividing attention with simultaneous tasks may impede performance while producing specific brain activation patterns. We hypothesized that combining voluntary movement with visual attention would yield unique brain representations differing from those occurring for movement or visual attention alone. Hemodynamic signals in humans were obtained with functional magnetic resonance imaging (MRI) while participants performed one of four tasks that required only a repetitive finger movement, only attending to the color of a visual stimulus, simultaneous finger movement and visual attention, or no movement and no visual attention. The movement-alone task yielded brain activation in structures commonly engaged during voluntary movement, including the primary motor cortex, supplementary motor area, and cerebellum. Visual attention alone resulted in sparse cerebral cortical and substantial bilateral cerebellar activation. Simultaneous performance of visual attention and finger movements yielded widespread cerebral cortical, cerebellar, and other subcortical activation, in many of the same sites activated for the movement or attention tasks. However, the movement-related plus attention-related activation extended beyond the movement-alone or attention-alone activation sites, indicating a novel activation pattern related to the combined performance of attention and movement. Additionally, the conjoint effects of visual attention and movement upon brain activation were probably not simple gain effects, since we found activation-related interactions in the left superior parietal lobule, the right fusiform gyrus, and left insula, indicating a potent combinatory role for visual attention and movement for activation patterns in the human brain. In conclusion, performing visual attention and movement tasks simultaneously, even though the tasks had no specific interrelationship, resulted in novel activation patterns not predicted by performing movements or visual attention alone. Electronic Publication     

Changes in corticospinal drive to spinal motoneurones following visuo-motor skill learning in humans

We have previously demonstrated an increase in the excitability of the leg motor cortical area in relation to acquisition of a visuo-motor task in healthy humans. It remains unknown whether the interaction between corticospinal drive and spinal motoneurones is also modulated following motor skill learning. Here we investigated the effect of visuo-motor skill training involving the ankle muscles on the coupling between electroencephalographic (EEG) activity recorded from the motor cortex (Cz) and electromyographic (EMG) activity recorded from the left tibialis anterior (TA) muscle in 11 volunteers. Coupling in the time (cumulant density function) and frequency domains (coherence) between EEG–EMG and EMG–EMG activity were calculated during tonic isometric dorsiflexion before and after 32 min of training a visuo-motor tracking task involving the ankle muscles or performing alternating dorsi- and plantarflexion movements without visual feedback. A significant increase in EEG–EMG coherence around 15–35 Hz was observed following the visuo-motor skill session in nine subjects and in only one subject after the control task. Changes in coherence were specific to the trained muscle as coherence for the untrained contralateral TA muscle was unchanged. EEG and EMG power were unchanged following the training. Our results suggest that visuo-motor skill training is associated with changes in the corticospinal drive to spinal motorneurones. Possibly these changes reflect sensorimotor integration processes between cortex and muscle as part of the motor learning process.     

Alcohol dementia: "cortical" or "subcortical" dementia?

Most dementias are considered to exhibit either a predominantly "cortical" (e.g. Alzheimer's disease, AD) or "subcortical" (e.g. Parkinson's disease) pattern. A double dissociation has been reported, such that cortical and subcortical dementias can be differentiated based on performance on tests of declarative and procedural learning. The goal of this study was to determine if subjects with alcohol dementia exhibit a predominantly cortical or subcortical dementia profile. The performance of 10 elderly subjects diagnosed with alcohol dementia, 29 elderly subjects with histories of alcohol dependence but who were not demented, and 11 subjects with AD was compared to 20 elderly control subjects. The results indicated that the procedural learning task did not differentiate among the groups, whereas the discriminability index from the California Learning Test (the declarative learning task) did. Thus, alcohol dementia cannot clearly be ascribed to either dementia classification.     

High-Resolution EEG Analysis of Power Spectral Density Maps and Coherence Networks in a Proportional Reasoning Task

Proportional reasoning is very important logical skill required in mathematics and science problem solving as well as in everyday life decisions. However, there is a lack of studies on neurophysiological correlates of proportional reasoning. To explore the brain activity of healthy adults while performing a balance scale task, we used high-resolution EEG techniques and graph-theory based connectivity analysis. After unskilled subjects learned how to properly solve the task, their cortical power spectral density (PSD) maps revealed an increased parietal activity in the beta band. This indicated that subjects started to perform calculations. In addition, the number of inter-hemispheric connections decreased after learning, implying a rearrangement of the brain activity. Repeated performance of the task led to the PSD decrease in the beta and gamma bands among parietal and frontal regions along with a synchronization of lower frequencies. These findings suggest that repetition led to a more automatic task performance. Subjects were also divided in two groups according to their scores on the test of logical thinking (TOLT). Although no group differences in the accuracy and reaction times were found, EEG data showed higher activity in the beta and gamma bands for the group that scored better on TOLT. Learning and repetition induced changes in the pattern of functional connectivity were evident for all frequency bands. Overall, the results indicated that higher frequency oscillations in frontal and parietal regions are particularly important for proportional reasoning.     

Neural networks active during tactile form perception: common and differential activity during macrospatial and microspatial tasks.

Prior studies have shown that tactile perception recruits activity not only in somatosensory but also in visual cortical areas. The present study used functional magnetic resonance imaging to investigate the distribution of neural activity during tactile perception of 2D form. In a macrospatial form task, raised letters (uppercase T and V) were presented upside-down. In a microspatial form task, a bar, either with or without a gap, was presented. Stimuli were applied to the immobilized right index fingerpad. Six neurologically normal volunteers were studied in a block design paradigm, with alternating blocks of rest and covert discrimination between the two alternatives for a task. Each task was studied in a separate run. Contrasting macrospatial form discrimination against rest revealed activity in an extensive, bilateral network of cortical and subcortical regions, including areas of somatosensory cortex and the intraparietal sulcus (IPS), occipito-temporal cortex, dorsal and ventral premotor cortex, medial superior frontal cortex, lateral inferior frontal cortex, thalamus and cerebellar hemispheres. Contrasting (microspatial) gap detection against rest showed activity in a similar network, with the notable exception of the occipito-temporal cortical regions. A direct contrast between the two tasks yielded greater activity for the macrospatial than microspatial task in these occipito-temporal regions bilaterally, and also in foci near the right IPS and in the right cerebellar hemisphere. The occipito-temporal cortical activations were in the lateral occipital complex, a part of the ventral visual pathway active during visual form perception. Thus, macrospatial form perception preferentially recruits this region of extrastriate visual cortex, compared to microspatial form perception.