title: Spontaneous Changes in Taste Sensitivity of Single Units Recorded over Consecutive Days in the Brainstem of the Awake Rat.
abstract: A neuron's sensitivity profile is fundamental to functional classification of cell types, and underlies theories of sensory coding. Here we show that gustatory neurons in the nucleus of the solitary tract (NTS) and parabrachial nucleus of the pons (PbN) of awake rats spontaneously change their tuning properties across days. Rats were surgically implanted with a chronic microwire assembly into the NTS or PbN. Following recovery, water-deprived rats had free access to a lick spout that delivered taste stimuli while cellular activity was recorded. In 12 rats for the NTS and 8 rats for the PbN, single units could be isolated at the same electrode on consecutive days (NTS, 14 units for 2-5 consecutive days, median = 2 days; PbN, 23 units for 2-7 days, median = 2.5 days). Waveforms were highly similar (waveform template correlation > 0.99) across days in 13 units in NTS and 13 units in PbN. This degree of similarity was rare (0.3% of pairs in NTS, 1.5% of pairs in PbN) when the waveforms were from presumed-different neurons (units recorded on nonconsecutive days with at least one intervening day in which there were no spikes, or from different wires or rats). Analyses of multi-day recordings that met this criterion for "same unit" showed that responses to taste stimuli appeared, disappeared, or shifted in magnitude across days, resulting in changes in tuning. These data imply, generally, that frameworks for cell classification and, specifically, that theories of taste coding, need to consider plasticity of response profiles.
authors.affiliation: Department of Psychology, Binghamton University, Binghamton, New York, United States of America.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Sammons
authors.affiliation: Department of Psychology, Binghamton University, Binghamton, New York, United States of America.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Weiss
authors.affiliation: Department of Psychology, Binghamton University, Binghamton, New York, United States of America.
authors.forename: Olga D
authors.initials: OD
authors.lastname: Escanilla
authors.affiliation: Department of Psychology, Binghamton University, Binghamton, New York, United States of America.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Fooden
authors.affiliation: Feil Family Brain and Mind Research Institute and Department of Neurology, Weill Cornell Medical College, New York, New York, United States of America.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Victor
authors.affiliation: Department of Psychology, Binghamton University, Binghamton, New York, United States of America.
authors.forename: Patricia M
authors.identifier: http://orcid.org/0000-0003-3935-1089
authors.initials: PM
authors.lastname: Di Lorenzo
mesh_terms: D000818:Animals; D004567:Electrodes, Implanted; D055724:Electrophysiological Phenomena; D008297:Male; D065823:Parabrachial Nucleus / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000502:physiology*; D013649:Taste / Q000502:physiology*; D055697:Taste Perception / Q000502:physiology*; D014851:Wakefulness