title: Modifications of the responses of barrel field neurons to vibrissal stimulation during theta in the awake and undrugged rat.
abstract: In partially restrained but awake and undrugged rats, excitatory unit responses of the somatic cortex barrel field to vibrissal stimulation, were recorded in two conditions: during spontaneous episodes of theta and in the absence of this rhythm. Two main variables were considered: a signal-to-noise ratio and an index of the "afferent inhibition". Both measures were extracted from peristimulus time histograms. "Theta effects" were characterized by an increase in signal-to-noise ratio and afferent inhibition. They were most important in neurons located in infragranular layers of the cortex; they went in the same direction but only approached significance in supragranular neurons; neurons of the granular layer were not affected. Spontaneous unit activity and latencies were not modified in any group. These data were obtained during a preliminary step of a sensory-sensory conditioning procedure which in some cases modified the receptive field of the neurons. Theta effects were less marked in future "conditioned" than in future non-conditioned neurons but this was probably due to the fact that conditioned neurons had significantly higher signal-to-noise ratio and afferent inhibition. The origin of these "theta effects", hippocampal versus non-hippocampal, and their functional significance, relation to selective attention, are discussed.
authors.affiliation: Laboratoire de Psychophysiologie, Université Paris 7, France.
authors.forename: J
authors.initials: J
authors.lastname: Delacour
authors.forename: O
authors.initials: O
authors.lastname: Houcine
authors.forename: J C
authors.initials: JC
authors.lastname: Costa
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D004569:Electroencephalography; D006624:Hippocampus / Q000502:physiology; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology*; D009475:Neurons, Afferent / Q000502:physiology; D051381:Rats; D013003:Somatosensory Cortex / Q000502:physiology; D013238:Stereotaxic Techniques; D013826:Theta Rhythm