title: Brain state effects on layer 4 of the awake visual cortex.
abstract: Awake mammals can switch between alert and nonalert brain states hundreds of times per day. Here, we study the effects of alertness on two cell classes in layer 4 of primary visual cortex of awake rabbits: presumptive excitatory "simple" cells and presumptive fast-spike inhibitory neurons (suspected inhibitory interneurons). We show that in both cell classes, alertness increases the strength and greatly enhances the reliability of visual responses. In simple cells, alertness also increases the temporal frequency bandwidth, but preserves contrast sensitivity, orientation tuning, and selectivity for direction and spatial frequency. Finally, alertness selectively suppresses the simple cell responses to high-contrast stimuli and stimuli moving orthogonal to the preferred direction, effectively enhancing mid-contrast borders. Using a population coding model, we show that these effects of alertness in simple cells--enhanced reliability, higher gain, and increased suppression in orthogonal orientation-could play a major role at increasing the speed of cortical feature detection.
authors.affiliation: Department of Psychology, University of Connecticut, Storrs, Connecticut 06269, and Department of Biological Sciences, State University of New York College of Optometry, New York, New York 10036.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhuang
authors.forename: Yulia
authors.initials: Y
authors.lastname: Bereshpolova
authors.forename: Carl R
authors.initials: CR
authors.lastname: Stoelzel
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Huff
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Hei
authors.forename: Jose-Manuel
authors.initials: JM
authors.lastname: Alonso
authors.forename: Harvey A
authors.initials: HA
authors.lastname: Swadlow
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D007395:Interneurons / Q000502:physiology*; D016014:Linear Models; D008959:Models, Neurological; D009433:Neural Inhibition / Q000502:physiology*; D009949:Orientation / Q000502:physiology; D011817:Rabbits; D014793:Visual Cortex / Q000166:cytology* / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology; D014851:Wakefulness / Q000502:physiology*