Stimulus-timing-dependent plasticity in the visual cortex
University of California, Berkeley
Relative timing of pre- and postsynaptic spikes on the order of milliseconds plays a critical role in activity-induced, long-term synaptic modification, but the functional significance of such synaptic plasticity in vivo is only beginning to be examined. Since the timing of visual stimuli directly affects spike timing in visual neurons, it may play an important role in the plasticity of visual circuits. We have studied stimulus-timing-dependent plasticity in the adult visual cortex in both the orientation and the space domain. We found that repetitive pairing of visual stimuli at two orientations or two regions in visual space induced changes in the functional connectivity between cortical neurons and in response properties of individual neurons in the anesthetized cat. Similar stimuli also induced perceptual shifts in human subjects consistent with findings in the physiological experiments. Induction of these changes required that the interval between the pair of stimuli fall within a window on the order of tens of milliseconds, reminiscent of the temporal window for spike-timing-dependent synaptic plasticity. Thus, relative timing of visual stimuli on the order of tens of milliseconds can play a critical role in dynamic modulation of adult cortical function, perhaps through a process involving spike-timing-dependent synaptic plasticity.