Two parkinsonian patients who experienced transient hypomanic states when the subthalamic nucleus (STN) was stimulated during postoperative adjustment of the electrical parameters for antiparkinsonian therapy agreed to have the mood disorder reproduced, in conjunction with motor, cognitive, and behavioral evaluations and concomitant functional neuroimaging. During the experiment, STN stimulation again induced a hypomanic state concomitant with activation of cortical and thalamic regions known to process limbic and associative information. This observation suggests that the STN plays a role in the control of a complex behavior that includes emotional as well as cognitive and motor components. The localization of the four contacts of the quadripolar electrode was determined precisely with an interactive brain atlas. The results showed that (i) the hypomanic state was caused only by stimulation through one contact localized in the anteromedial STN; (ii) both this contact and the contact immediately dorsal to it improved the parkinsonian motor state; (iii) the most dorsal and ventral contacts, located at the boundaries of the STN, neither induced the behavioral disorder nor improved motor performance. Detailed analysis of these data led us to consider a model in which the three functional modalities, emotional, cognitive, and motor, are not processed in a segregated manner but can be subtly combined in the small volume of the STN. This nucleus would thus serve as a nexus that integrates the motor, cognitive, and emotional components of behavior and might consequently be an effective target for the treatment of behavioral disorders that combine emotional, cognitive, and motor impairment.basal ganglia ͉ emotion ͉ deep brain stimulation ͉ neuroimaging

The spiking activity of single neurons in the primate motor cortex is correlated with various limb movement parameters, including velocity. Recent findings obtained using local field potentials suggest that hand speed may also be encoded in the summed activity of neuronal populations. At this macroscopic level, the motor cortex has also been shown to display synchronized rhythmic activity modulated by motor behavior. Yet whether and how neural oscillations might be related to limb speed control is still poorly understood. Here, we applied magnetoencephalography (MEG) source imaging to the ongoing brain activity in subjects performing a continuous visuomotor (VM) task. We used coherence and phase synchronization to investigate the coupling between the estimated activity throughout the brain and the simultaneously recorded instantaneous hand speed. We found significant phase locking between slow (2-to 5-Hz) oscillatory activity in the contralateral primary motor cortex and time-varying hand speed. In addition, we report long-range task-related coupling between primary motor cortex and multiple brain regions in the same frequency band. The detected large-scale VM network spans several cortical and subcortical areas, including structures of the frontoparietal circuit and the cerebello-thalamo-cortical pathway. These findings suggest a role for slow coherent oscillations in mediating neural representations of hand kinematics in humans and provide further support for the putative role of long-range neural synchronization in large-scale VM integration. Our findings are discussed in the context of corticomotor communication, distributed motor encoding, and possible implications for brainmachine interfaces.large-scale networks ͉ magnetoencephalography ͉ motor cortex ͉ oscillations ͉ visuomotor integration N europhysiological recordings in nonhuman primates have revealed that neuronal discharges in primary motor cortex (M1) are correlated with various movement parameters, including hand speed (1, 2). Furthermore, recent findings show that information on hand speed may also be accessible, at a more macroscopic level, from the summed synaptic activity of neural populations by recording local field potentials (LFPs) in M1 (3). Velocity-related activity has also been found in other brain areas, including the premotor cortex (2), posterior parietal cortex (4), and cerebellum (5). Recent reports based on simultaneous multielectrode recordings (6, 7) lend further support to the hypothesis that limb kinematics are encoded in multiple cortical areas. In humans, cerebral areas involved in speed control can be detected with functional imaging (8, 9). However, the investigation of the underlying neural mechanisms requires high (millisecond-range) temporal resolution and is still poorly understood.Evidence from a parallel body of research investigating rhythmic activity in motor cortex, its relationship to peripheral motor behavior (10, 11), and its interaction with muscle activity (12)(13)(14)(15)(16)(17)(18)(19)(20) suggests that ne...

How the processing of emotional expression is influenced by perceived gaze remains a debated issue. Discrepancies between previous results may stem from differences in the nature of stimuli and task characteristics. Here we used a highly controlled set of computer-generated animated faces combining dynamic emotional expressions with varying intensity, and gaze shifts either directed at or averted from the observer. We predicted that perceived self-relevance of fearful faces would be higher with averted gaze-signaling a nearby danger; whereas conversely, direct gaze would be more relevant for angry faces-signaling aggressiveness. This interaction pattern was observed behaviorally for emotion intensity ratings, and neurally for functional magnetic resonance imaging activation in amygdala, as well as fusiform and medial prefrontal cortices, but only for mild- and not high-intensity expressions. These results support an involvement of human amygdala in the appraisal of self-relevance and reveal a crucial role of expression intensity in emotion and gaze interactions.

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