The contributions of inhibition and noise to responses in V1

Thomas Z. Lauritzen, Kenneth D. Miller

Abstract: We include a recently described class of inhibitory cells, complex cells untuned for orientation, as well as simple cells in a model of V1 to study their contribution in shaping simple cell responses. Untuned complex cell inhibition can suffice to explain contrast-invariant orientation-tuning and low-pass temporal frequency tuning of cortical simple cells. Given this complex cell inhibition, antiphase (“push–pull”) inhibition from tuned simple inhibitory neurons acts to sharpen spatial frequency tuning and increase the stability of cortical activity. Intracortical inhibition is needed to achieve contrast-invariance of the voltage tuning, which is converted by physiological noise levels into contrast-invariant spike tuning.