If you close your eyes you can still image the world around you, and, with your eyes closed point to the spatial location of objects in the world. Patients with lesions of the parietal cortex have deficits in visual memory, and cannot locate objects in the world with their eyes closed. We have discovered that neurons in the lateral intraparietal area, a region in the parietal lobe, maintain a memory of objects in the environment across several trials. When a subject makes a saccade that brings the spatial location of a remembered object into the receptive field of a neuron, the neuron responds as if the object were still there, although with a longer latency and lesser (although still significant) response.
The aims of this proposal are to determine the brain areas upon which this environmental memory depends. We will examine the role of three candidates: the frontal eye field, the parahippocampal gyrus, and the eye position region of primary somatosensory cortex.
Normal humans have a detailed visual memory of their environment. With their eyes closed they can point to objects in their environment, or describe familiar places. Patients with lesions of the parietal lobe cannot do this, and the absence of visual memory for action interferes with their rehabilitative potential. This proposal seeks to understand the basic neurophysiology responsible for this environmental memory, in order better to be able to plan rehabilitative strategies.
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