title: Efficient population coding of naturalistic whisker motion in the ventro-posterior medial thalamus based on precise spike timing.
abstract: The rodent whisker-associated thalamic nucleus (VPM) contains a somatotopic map where whisker representation is divided into distinct neuronal sub-populations, called "barreloids". Each barreloid projects to its associated cortical barrel column and so forms a gateway for incoming sensory stimuli to the barrel cortex. We aimed to determine how the population of neurons within one barreloid encodes naturalistic whisker motion. In rats, we recorded the extracellular activity of up to nine single neurons within a single barreloid, by implanting silicon probes parallel to the longitudinal axis of the barreloids. We found that play-back of texture-induced whisker motion evoked sparse responses, timed with millisecond precision. At the population level, there was synchronous activity: however, different subsets of neurons were synchronously active at different times. Mutual information between population responses and whisker motion increased near linearly with population size. When normalized to factor out firing rate differences, we found that texture was encoded with greater informational-efficiency than white noise. These results indicate that, within each VPM barreloid, there is a rich and efficient population code for naturalistic whisker motion based on precisely timed, population spike patterns.
authors.affiliation: School of Life Sciences, University of Sussex Brighton, UK ; Faculty of Life Sciences, University of Manchester Manchester, UK ; Instituto de Neurociencias Alicante UMH-CSIC Sant Joan d'Alacant, Spain.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Bale
authors.affiliation: Faculty of Life Sciences, University of Manchester Manchester, UK ; Institute of Neuroscience and Psychology, University of Glasgow Glasgow, UK.
authors.forename: Robin A A
authors.initials: RA
authors.lastname: Ince
authors.affiliation: Faculty of Life Sciences, University of Manchester Manchester, UK.
authors.forename: Greta
authors.initials: G
authors.lastname: Santagata
authors.affiliation: Faculty of Life Sciences, University of Manchester Manchester, UK.
authors.forename: Rasmus S
authors.initials: RS
authors.lastname: Petersen
mesh_terms: D000818:Animals; D004569:Electroencephalography; D055724:Electrophysiological Phenomena / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013003:Somatosensory Cortex / Q000502:physiology*; D020651:Ventral Thalamic Nuclei / Q000502:physiology*; D014738:Vibrissae / Q000502:physiology*
keywords: VPM; information theory; neural coding; somatosensory; synchrony; vibrissa