Grant Number: 5R01EY013135-07
Project Title: Spatiotemporal Maps & Interactions in Directional Cells
PI Information: PROFESSOR MARGARET S. LIVINGSTONE, mlivingstone@hms.harvard.edu 

Abstract: DESCRIPTION (provided by applicant):
The goal of this project is to describe how an extrastriate visual area, MT, generates response properties not present in its inputs. One novel aspect of this study is that the average input properties will be determined first from 2nd order properties of the MT cell, then stimuli tailored to match the inputs will be used to study how the inputs are combined and modified by the MT cell. A full mathematical description of the local-motion detectors making up each MT cell's receptive field will be used to determine which response properties can be accounted for by the cell's inputs and which properties require further processing. For response properties that do require higher-level processing, the computations underlying these properties will be explored by comparing the response properties with the spatial distribution of the inputs and the interactions between those inputs. Understanding how excitatory and inhibitory inputs to an extrastriate area are spatially distributed and combined should elucidate fundamental principles of information processing and cortical organization. The proposed interaction studies will explore integrative processes that might underlie such phenomena as hysteresis in motion perception, motion cooperativity, speed tuning, and sensitivity to continuous trajectories. The proposed studies on speed selectivity as a function of contrast may have implications for the kinds of automobile driving errors expected for medical conditions that reduce vision contrast, such as early cataracts. This laboratory has used similar stimuli and analytical approaches to study direction, disparity, and color processing in primary visual cortex, achieving most of the goals for the previous proposal, and has recently successfully applied these approaches to extrastriate area MT. The proposed studies, and the novel iterative mapping technique, are an extension of these studies to the next-higher stage of motion processing.

Thesaurus Terms:
brain mapping, cell cell interaction, interneuron, motion perception, neuroanatomy, synapse, visual cortex
eye movement, visual field, visual pathway, visual stimulus
Macaca mulatta, electrophysiology

Institution: HARVARD UNIVERSITY (MEDICAL SCHOOL)
MEDICAL SCHOOL CAMPUS
BOSTON, MA 02115
Fiscal Year: 2006
Department: NEUROBIOLOGY
Project Start: 30-SEP-2000
Project End: 31-JUL-2008
ICD: NATIONAL EYE INSTITUTE
IRG: CVP

Cerebral Cortex Advance Access originally published online on November 23, 2005

Cerebral Cortex 2006 16(9):1332-1337

V1 Partially Solves the Stereo Aperture Problem
 
Piers D. L. Howe and Margaret S. Livingstone

Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue Alpert 232, Boston, MA 02115, USA

Address correspondence to Piers D. L. Howe. Email: phowe@hms.harvard.edu

In brief, these experiments used a male (R) and female (J) rhesus macaque monkey (Macaca mulatta). During the experiment the alert monkey was seated comfortably in a standard primate chair (Crist Instruments, Hagerstown, Maryland) with its head fixed and maintained foveation on a fixation point for a juice reward. We isolated approximately 315 single units but only 55 were both disparity sensitive and sufficiently stable to allow further study.