Attentional Modulation of Tilt Aftereffect Caused by Cholinergic Basal Forebrain Projections

Psychophysical experiments show that adaptation induced tilt aftereffect gets modulated under controlled conditions of attention. The underlying neurophysiological mechanisms are unknown. Here using a population model of primary visual cortex having detailed intrinsic and synaptic mechanisms we model orientation adaptation and the effect of attention. We report that increased attention to orientation of adapting stimulus reduces magnitude of the tilt aftereffect by modulating feedforward and intracortical synaptic efficacies. Without mechanisms for synaptic modulation, increased alertness tends to increase the magnitude of the tilt aftereffect via modulation of intrinsic membrane mechanisms. Our model is the first to relate multiple acetylcholine-induced modulations of membrane and synaptic conductances to adaptation induced aftereffects. We also report that attention to stimulus orientation opposes adaptation induced orientation plasticity, reducing the adaptation induced repulsive shift of orientation preferences.