title: Transformation of adaptation and gain rescaling along the whisker sensory pathway.
abstract: Neurons in all sensory systems have a remarkable ability to adapt their sensitivity to the statistical structure of the sensory signals to which they are tuned. In the barrel cortex, firing rate adapts to the variance of a whisker stimulus and neuronal sensitivity (gain) adjusts in inverse proportion to the stimulus standard deviation. To determine how adaptation might be transformed across the ascending lemniscal pathway, we measured the responses of single units in the first and last subcortical stages, the trigeminal ganglion (TRG) and ventral posterior medial thalamic nucleus (VPM), to controlled whisker stimulation in urethane-anesthetized rats. We probed adaptation using a filtered white noise stimulus that switched between low- and high-variance epochs. We found that the firing rate of both TRG and VPM neurons adapted to stimulus variance. By fitting the responses of each unit to a Linear-Nonlinear-Poisson model, we tested whether adaptation changed feature selectivity and/or sensitivity. We found that, whereas feature selectivity was unaffected by stimulus variance, units often exhibited a marked change in sensitivity. The extent of these sensitivity changes increased systematically along the pathway from TRG to barrel cortex. However, there was marked variability across units, especially in VPM. In sum, in the whisker system, the adaptation properties of subcortical neurons are surprisingly diverse. The significance of this diversity may be that it contributes to a rich population representation of whisker dynamics.
authors.affiliation: Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Maravall
authors.affiliation: Instituto de Neurociencias de Alicante, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández, Sant Joan d'Alacant, Alicante, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Alenda
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bale
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Petersen
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000222:Adaptation, Physiological; D000818:Animals; D008959:Models, Neurological; D009068:Movement; D009474:Neurons / Q000502:physiology; D017711:Nonlinear Dynamics; D051381:Rats; D012677:Sensation / Q000502:physiology*; D013003:Somatosensory Cortex / Q000502:physiology; D014738:Vibrissae / Q000502:physiology*