Dynamics of directional selectivity in MT receptive field centre and surround
Perge, János A. ; Borghuis, Bart G. ; Bours, Roger J.E. ; Lankheet, Martin J.M. ; Wezel, Richard J.A. Van - \ 2005
European Journal of Neuroscience 22 (2005)8. - ISSN 0953-816X - p. 2049 - 2058.
Electrophysiology - Extrastriate cortex - Macaque monkey - Middle temporal area - Motion perception
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.