Parietal cortex and movement (original) (raw)
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Non-spatial, motor-specific activation in posterior parietal cortex
Nature Neuroscience, 2002
Posterior parietal cortex (PPC) seems to process spatial information in a way that is strongly influenced by how that information will be used 1-3 . The response to a visual and auditory stimulus in a cell's receptive field is often enhanced when that stimulus is behaviorally relevant 3-9 . The enhancement is not merely all or none; activity in the lateral intraparietal area (LIP), for example, seems to be continuously modulated by the return (reward) associated with a given target 10 .
Motor functions of the parietal lobe
Current Opinion in Neurobiology, 2005
There is now general agreement that the posterior parietal cortex is part of the motor system. New data have confirmed its fundamental role in visuomotor transformations. Most interestingly, recent data showed that the inferior parietal lobule codes motor acts (such as grasping) in a specific way according to the action in which they are embedded. This particular motor organization appears to provide a neural mechanism for higher order cognitive motor functions, including understanding of intention. These functions, and peripersonal space representation, are represented in areas of the inferior parietal lobule, where visual information from both the dorsal and the ventral stream is integrated with motor information.
Sensorimotor Transformations in the Posterior Parietal Cortex
The posterior parietal cortex (PPC) sits at the interface between sensory and motor areas and performs sensorimotor transformations. Current research is beginning to unravel the details of this transformation process. The first part of this chapter focuses on planning signals found in the PPC. Experiments show that the thought to reach can be read out from the parietal reach region of monkeys and used to control the position of a computer cursor without any reach movements being made by the monkeys. The second section reviews recent studies of coordinate tral15formations, which are an important aspect of sensorimotor transformations and involve the PPC.
Parietal cortex: from sight to action
Current opinion in neurobiology, 1997
the functional role of the parietal cortex. According to this view, the parietal lobe consists of a multiplicity of areas with specific connections to the frontal lobe. These areas, together with the frontal areas to which they are connected, mediate distinct sensorimotor transformations related to the control of hand, arm, eye or head movements. Space perception is not unitary, but derives from the joint activity of the fronto-parietal circuits that control actions requiring space computation.
Current Biology, 2003
regions include several parietal areas [5, 7, 8] that not only receive afferent inputs from different sensory mo-United Kingdom 2 Wellcome Department of Imaging Neuroscience dalities [10, 11] but also send direct efferent projections to particular premotor and prefrontal areas involved in Institute of Neurology Functional Imaging Laboratory one or another type of motor response [12-14]. Recently, brain imaging techniques have been used 12 Queen Street London, WC1N 3BG to search for multimodal brain areas in humans [15-19]. In one representative study [18], vision, touch, or audi-United Kingdom tion was stimulated. In comparison with baselines, all three modalities activated ventral intraparietal sulcus and inferior parietal cortex (plus premotor regions), con-Summary sistent with convergence of different sensory modalities to human parietal cortex. However, spatial location was Background: Recent neuroimaging studies have found not manipulated systematically in this or related multithat several areas of the human brain, including parietal modal studies [16, 17, 19]. Other crossmodal studies regions, can respond multimodally. But given single-cell used localization tasks [20]
The role of parietal cortex in visuomotor control: What have we learned from neuroimaging
Neuropsychologia, 2006
Research from macaque neurophysiology and human neuropsychology has implicated the parietal cortex in the sensory control of action. Functional neuroimaging has been very valuable in localizing and characterizing specific regions of the human brain involved in visuomotor actions involving different effectors, such as the eyes, head, arms and hands. Here, we review the areas discovered by human neuroimaging, including the putative functional equivalents of the following macaque regions: parietal eye fields (PEF), ventral intraparietal (VIP) area, parietal reach region (PRR) and the anterior intraparietal (AIP) area. We discuss the challenges of studying realistic movements in the imaging environment, the lateralization of visuomotor function, caveats involved in proposing interspecies homologies and the limitations and future directions for neuroimaging studies of visuomotor control.
Frontiers in Human Neuroscience, 2015
To reach for an object, we must convert its spatial location into an appropriate motor command, merging movement direction and amplitude. In humans, it has been suggested that this visuo-motor transformation occurs in a dorsomedial parieto-frontal pathway, although the causal contribution of the areas constituting the "reaching circuit" remains unknown. Here we used transcranial magnetic stimulation (TMS) in healthy volunteers to disrupt the function of either the medial intraparietal area (mIPS) or dorsal premotor cortex (PMd), in each hemisphere. The task consisted in performing steptracking movements with the right wrist towards targets located in different directions and eccentricities; targets were either visible for the whole trial (Target-ON) or flashed for 200 ms (Target-OFF). Left and right mIPS disruption led to errors in the initial direction of movements performed towards contralateral targets. These errors were corrected online in the Target-ON condition but when the target was flashed for 200 ms, mIPS TMS manifested as a larger endpoint spreading. In contrast, left PMd virtual lesions led to higher acceleration and velocity peaks-two parameters typically used to probe the planned movement amplitude-irrespective of the target position, hemifield and presentation condition; in the Target-OFF condition, left PMd TMS induced overshooting and increased the endpoint dispersion along the axis of the target direction. These results indicate that left PMd intervenes in coding amplitude during movement preparation. The critical TMS timings leading to errors in direction and amplitude were different, namely 160-100 ms before movement onset for mIPS and 100-40 ms for left PMd. TMS applied over right PMd had no significant effect. These results demonstrate that, during motor preparation, direction and amplitude of goal-directed movements are processed by different cortical areas, at distinct timings, and according to a specific hemispheric organization.
Multisensory maps in parietal cortex
Current Opinion in Neurobiology, 2014
Parietal cortex has long been known to be a site of sensorimotor integration. Recent findings in humans have shown that it is divided up into a number of small areas somewhat specialized for eye movements, reaching, and hand movements, but also face-related movements (avoidance, eating), lower body movements, and movements coordinating multiple body parts. The majority of these areas contain rough sensory (receptotopic) maps, including a substantial multisensory representation of the lower body and lower visual field immediately medial to face VIP. There is strong evidence for retinotopic remapping in LIP and face-centered remapping in VIP, and weaker evidence for hand-centered remapping. The larger size of the functionally distinct inferior parietal default mode network in humans compared to monkeys results in a superior and medial displacement of middle parietal areas (e.g., the saccade-related LIP's). Multisensory superior parietal areas located anterior to the angular gyrus such as AIP and VIP are less medially displaced relative to macaque monkeys, so that human LIP paradoxically ends up medial to human VIP.
Role of the medial parieto-occipital cortex in the control of reaching and grasping movements
Experimental Brain Research, 2003
The medial parieto-occipital cortex is a central node in the dorsomedial visual stream. Recent physiological studies in the macaque monkey have demonstrated that the medial parieto-occipital cortex contains two areas, the visual area V6 and the visuomotor area V6A. Area V6 is a retinotopically organized visual area that receives form and motion information directly from V1 and is heavily connected with the other areas of the dorsal visual stream, including V6A. Area V6A is a bimodal visual/somatosensory area that elaborates visual information such as form, motion and space suitable for the control of both reaching and grasping movements. Somatosensory and skeletomotor activities in V6A affect the upper limbs and involve both the transport phase of reaching and grasping movements. Finally, V6A is strongly and reciprocally connected with the dorsal premotor cortex controlling arm movements. The picture emerging from these data is that the medial parieto-occipital cortex is well equipped to control both proximal and distal movements in the online visuomotor guidance of prehension. In agreement with this view, selective V6A lesions in monkey produce misreaching and misgrasping with the arm contralateral to the lesion in visually guided movements. These deficits are similar to those observed in optic ataxia patients and suggest that human and monkey superior parietal lobules are homologous structures, and that optic ataxia syndrome is the result of the lesion of a 'human' area V6A.