title: A spontaneous state of weakly correlated synaptic excitation and inhibition in visual cortex.
abstract: Cortical spontaneous activity reflects an animal's behavioral state and affects neural responses to sensory stimuli. The correlation between excitatory and inhibitory synaptic input to single neurons is a key parameter in models of cortical circuitry. Recent measurements demonstrated highly correlated synaptic excitation and inhibition during spontaneous "up-and-down" states, during which excitation accounted for approximately 80% of inhibitory variance (Shu et al., 2003; Haider et al., 2006). Here we report in vivo whole-cell estimates of the correlation between excitation and inhibition in the rat visual cortex under pentobarbital anesthesia, during which up-and-down states are absent. Excitation and inhibition are weakly correlated, relative to the up-and-down state: excitation accounts for less than 40% of inhibitory variance. Although these correlations are lower than when the circuit cycles between up-and-down states, both behaviors may arise from the same circuitry. Our observations provide evidence that different correlational patterns of excitation and inhibition underlie different cortical states.
authors.affiliation: Center for Perceptual Systems, Section of Neurobiology, School of Biological Sciences, College of Natural Sciences, The University of Texas at Austin, 2400 Speedway, Austin, TX 78705, USA. atyy@alum.mit.edu
authors.forename: A Y Y
authors.initials: AY
authors.lastname: Tan
authors.forename: S
authors.initials: S
authors.lastname: Andoni
authors.forename: N J
authors.initials: NJ
authors.lastname: Priebe
mesh_terms: D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D005260:Female; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D009435:Synaptic Transmission / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*
keywords: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; CI; HEPES; confidence interval; correlation; excitation; in vivo; inhibition; primary visual cortex; spontaneous activity