title: Dynamics of excitation and inhibition underlying stimulus selectivity in rat somatosensory cortex.
abstract: Neurons in sensory systems respond to stimuli within their receptive fields, but the magnitude of the response depends on specific stimulus features. In the rodent whisker system, the response magnitude to the deflection of a particular whisker is, in most cells, dependent on the direction of deflection. Here we use in vivo intracellular recordings from thalamorecipient neurons in layers 3 and 4 of the rat barrel cortex to elucidate the dynamics of the synaptic inputs underlying direction selectivity. We show that cells are direction selective despite a broadly tuned excitatory and inhibitory synaptic input. Selectivity emerges from a direction-dependent temporal shift of excitation relative to inhibition. For preferred direction deflections, excitation precedes inhibition, but as the direction diverges from the preferred, this separation decreases. Our results illustrate a mechanism by which the timing of the synaptic inputs, and not their relative peak amplitudes, primarily determine feature selectivity.
authors.affiliation: Department of Neuroscience, University of Pennsylvania School of Medicine, 215 Stemmler Hall, Philadelphia, Pennsylvania 19106, USA.
authors.forename: W Bryan
authors.initials: WB
authors.lastname: Wilent
authors.forename: Diego
authors.initials: D
authors.lastname: Contreras
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D004553:Electric Conductivity; D004558:Electric Stimulation / Q000379:methods; D008012:Lidocaine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009433:Neural Inhibition / Q000502:physiology* / Q000528:radiation effects; D009474:Neurons / Q000502:physiology* / Q000528:radiation effects; D017711:Nonlinear Dynamics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology / Q000528:radiation effects; D013003:Somatosensory Cortex / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D013569:Synapses / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors; D014738:Vibrissae / Q000502:physiology
chemical_list: D000779:Anesthetics, Local; C012647:QX-314; D008012:Lidocaine