PubMed Health⌕ Search

Biomedical subjects

Dieter F Kutz

Publications and source records attributed to Dieter F Kutz.

5 recordsLinked to original sources
PubMed2005

The relationship between V6 and PO in macaque extrastriate cortex.

The cerebral cortex of three macaque monkeys, electrophysiologically studied in chronic preparations in order to recognize functionally the medial parieto-occipital area V6, was reconstructed using the software CARET. Locations of cells recorded from area V6 (n = 553) and from neighbouring cortical areas V2/V3 and V6A (n = 1341) were displayed on surface-based reconstructions of individual brains, and on a surface-based atlas of the macaque cerebral cortex. Results show that area V6 occupies the ventral part and fundus of the parieto-occipital sulcus, as well as the ventral part of the precuneate cortex. V6 borders areas V2/V3 posteriorly and laterally, and area V6A anteriorly. The visualization of individual cases on a common template (atlas), and the use of atlas datasets, allowed us to compare data coming from different individuals and different laboratories. In particular, a comparison of the location and extent of the medial parieto-occipital areas V6 and PO indicates that area PO occupies different locations according to different authors but in general includes parts of both areas V6 and V6A. We therefore suggest that the term V6 is a more appropriate designation of the visuotopically-organized area located on the anterior wall of the parieto-occipital sulcus.

Action Potentials↗
PubMed2005

Spatial tuning of reaching activity in the medial parieto-occipital cortex (area V6A) of macaque monkey.

We recorded neural activity from the medial parieto-occipital area V6A while three monkeys performed an instructed-delay reaching task in the dark. Targets to be reached were in different spatial positions. Neural discharges were recorded during reaching movements directed outward from the body (towards visual objects), during the holding phase (when the hand was on the target) and during inward movements of the hand towards the home button (which was near the body and outside the field of view). Reach-related activity was observed in the majority of 207 V6A cells, during outward (78%) and inward (65%) movements as well as during the holding phase (62%). Most V6A reaching neurons (84%) were modulated in more than one phase of the task. The reach-related activity in V6A could depend on somatosensory inputs and/or on corollary discharges from the dorsal premotor cortex. Although visual and oculomotor inputs are known to have a strong influence on V6A activity, we excluded the possibility that the reach-related activity which we observed was due to visual stimulation and/or oculomotor activity. Reach-related activity for movements towards different locations was spatially modulated during outward (40%) and inward (47%) reaching movements. The position of the hand/arm in space modulated about 40% of V6A cells. Preferred reach directions and spatial locations were represented uniformly across the workspace. These data suggest that V6A reach-related neurons are able to code the direction of movement of the arm and the position of the hand/arm in space. We suggest that the V6A reach-related neurons are involved in the guidance of goal-directed arm movements, whether these actions are visually guided or not.

Action Potentials↗
PubMed2003

Role of the medial parieto-occipital cortex in the control of reaching and grasping movements.

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.

Animals↗
PubMed2002

Somatosensory cells in the parieto-occipital area V6A of the macaque.

The aim of this study was to assess whether neurones of area V6A, a part of Brodmann's area 19, are modulated by passive somatosensory stimulations. Extracellular activity was recorded in four awake while passive tactile stimulations of the skin and passive rotations of the joints were performed in complete darkness and under eye movement control. Out of 240 V6A units, 78 (32%) were modulated by somatosensory stimulations. The majority of somatic receptive fields were located on both proximal and distal parts of the contralateral arm. V6A somatosensory cells may play a role in the feedback control of the actual state of the arm while reaching its target in peripersonal space.

Animals↗