title: Cortical brightness adaptation when darkness and brightness produce different dynamical states in the visual cortex.
abstract: Darkness and brightness are very different perceptually. To understand the neural basis for the visual difference, we studied the dynamical states of populations of neurons in macaque primary visual cortex when a spatially uniform area (8° × 8°) of the visual field alternated between black and white. Darkness evoked sustained nerve-impulse spiking in primary visual cortex neurons, but bright stimuli evoked only a transient response. A peak in the local field potential (LFP) γ band (30-80 Hz) occurred during darkness; white-induced LFP fluctuations were of lower amplitude, peaking at 25 Hz. However, the sustained response to white in the evoked LFP was larger than for black. Together with the results on spiking, the LFP results imply that, throughout the stimulus period, bright fields evoked strong net sustained inhibition. Such cortical brightness adaptation can explain many perceptual phenomena: interocular speeding up of dark adaptation, tonic interocular suppression, and interocular masking.
authors.affiliation: State Key Laboratory of Cognitive Neuroscience and Learning and International Data Group (IDG)/McGovern Institute for Brain Research, and Center for Collaboration and Innovation in Brain and Learning Sciences, Beijing Normal University, Beijing 100875, China.
authors.forename: Dajun
authors.initials: D
authors.lastname: Xing
authors.forename: Chun-I
authors.initials: CI
authors.lastname: Yeh
authors.forename: James
authors.initials: J
authors.lastname: Gordon
authors.forename: Robert M
authors.initials: RM
authors.lastname: Shapley
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000222:Adaptation, Physiological; D000818:Animals; D003624:Darkness; D004594:Electrophysiology; D005074:Evoked Potentials, Visual; D008252:Macaca fascicularis; D009474:Neurons / Q000502:physiology; D010775:Photic Stimulation; D012815:Signal Processing, Computer-Assisted; D014785:Vision, Ocular; D014793:Visual Cortex / Q000502:physiology*; D014794:Visual Fields; D014796:Visual Perception / Q000502:physiology
keywords: cortical inhibition; laminar pattern; light adaptation