An important theme that has emerged from studies of the visual system is the tendency for neurons encoding different types of information to become anatomically segregated . The initial segregation of different types of information within an area, and subsequent anatomical divergence and physiological processing of that information, has a clear precedent in the Vl blob-to-V2 stripe organization of the macaque visual cortex. Results from 2-deoxyglucose experiments (Tootell and Born 1990) suggest that this type of parcellation of information continues within the """"""""motion pathway"""""""" neurons encoding two different kinds of visual motion (large-field vs. local motion contrast) are clustered in interdigitating columns in area MT. It is proposed to explore the nature and extent of this functional clustering to try to understand how information about visual motion is extracted, organized, and used by subsequent areas.
Specific aims of the project are: 1) To study the laminar and horizontal distribution of the receptive field properties in area MT using single unit electrophysiology combined with 2-deoxyglucose functional labelling and cytochrome oxidase histology. 2) To examine the nature of the interaction between center and surround in a subpopulation of surround-inhibited MT neurons. 3) To determine the intrinsic connections within area MT that may lead to the observed receptive field properties, by making tiny injections of horseradish peroxidase into MT. 4) To analyze the outputs of area MT, using conventional tract tracing methods, with respect to its modular organization in order to see how and to what extent different types of motion information remain segregated.
| Groh, J M; Born, R T; Newsome, W T (1997) How is a sensory map read Out? Effects of microstimulation in visual area MT on saccades and smooth pursuit eye movements. J Neurosci 17:4312-30 |
