Dynamics of directional selectivity in MT receptive field centre and surround.
We studied receptive field organization of motion-sensitive neurons in macaque middle temporal cortical area (MT), by mapping direction selectivity in space and in time. Stimuli consisted of pseudorandom sequences of single motion steps presented simultaneously at many different receptive field locations. Spatio-temporal receptive field profiles were constructed by cross-correlating stimuli and spikes. The resulting spike-triggered averages revealed centre-surround organization. The temporal dynamics of the receptive fields were generally biphasic with increased probability for the preferred direction at short latency (50-70 ms) and decreased probability at longer latency (80-100 ms). The response latency of the receptive field surround was on average 16 ms longer than that of the centre. Our results show that surround input and biphasic behaviour reflect two different mechanisms, which make MT cells specifically sensitive to motion contrast in space and time.
Perge
János A
JA
Functional Neurobiology, Helmholtz Institute, Faculty Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, Netherlands.
Borghuis
Bart G
BG
Bours
Roger J E
RJ
Lankheet
Martin J M
MJ
van Wezel
Richard J A
RJ
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D016014:Linear Models; D008253:Macaca mulatta; D008297:Male; D008954:Models, Biological; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D017711:Nonlinear Dynamics; D010812:Physical Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D013028:Space Perception / Q000502:physiology*; D013997:Time Factors; D014793:Visual Cortex / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology