Thalamocortical network dynamics can explain visual impulse responses and perceptual echoes

Abstract

Although temporal information is ubiquitous in natural vision, the cortex shows strong intrinsic rhythmicity. Recent electroencephalogram (EEG) studies have revealed a component of the visual impulse response function (IRF) resembling a narrow alpha-band (7–13 Hz) filter with a slow decay (the "perceptual echo"), but so far this has not been investigated at the cellular level. Here, we characterize responses in marmoset V1 to broadband visual flicker. The stimulus-locked dynamics were characterized by a non-oscillatory IRF and dominated by low frequencies. Spiking activity was coupled to the stimulus in a temporally sparse steady state, with individual units showing expected temporal frequency tuning. These dynamics can be explained by an established thalamocortical network model. We further show that under reduced damping the model reproduces the oscillatory dynamics observed in the awake human IRF. Our findings newly suggest a role for thalamocortical alpha resonance in the generation of the perceptual echoes.