title: Emergence of spatiotemporal invariance in large neuronal ensembles in rat barrel cortex.
abstract: Invariant sensory coding is the robust coding of some sensory information (e.g., stimulus type) despite major changes in other sensory parameters (e.g., stimulus strength). The contribution of large populations of neurons (ensembles) to invariant sensory coding is not well understood, but could offer distinct advantages over invariance in single cell receptive fields. To test invariant sensory coding in neuronal ensembles evoked by single whisker stimulation as early as primary sensory cortex, we recorded detailed spatiotemporal movies of evoked ensemble activity through the depth of rat barrel cortex using microelectrode arrays. We found that an emergent property of whisker evoked ensemble activity, its spatiotemporal profile, was notably invariant across major changes in stimulus amplitude (up to >200-fold). Such ensemble-based invariance was found for single whisker stimulation as well as for the integrated profile of activity evoked by the more naturalistic stimulation of the entire whisker array. Further, the integrated profile of whisker array evoked ensemble activity and its invariance to stimulus amplitude shares striking similarities to "funneled" tactile perception in humans. We therefore suggest that ensemble-based invariance could provide a robust neurobiological substrate for invariant sensory coding and integration at an early stage of cortical sensory processing already in primary sensory cortex.
authors.affiliation: Department of Neurobiology and Behavior, University of California, Irvine Irvine, CA, USA ; Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine Irvine, CA, USA.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Jacobs
authors.affiliation: Department of Neurobiology and Behavior, University of California, Irvine Irvine, CA, USA.
authors.forename: Cynthia H
authors.initials: CH
authors.lastname: Chen-Bee
authors.affiliation: Department of Neurobiology and Behavior, University of California, Irvine Irvine, CA, USA ; Department of Neurobiology and Behavior, Center for the Neurobiology of Learning and Memory, University of California, Irvine Irvine, CA, USA ; Department of Biomedical Engineering, University of California, Irvine Irvine, CA, USA.
authors.forename: Ron D
authors.initials: RD
authors.lastname: Frostig
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D004594:Electrophysiology; D008297:Male; D009474:Neurons / Q000502:physiology*; D010812:Physical Stimulation; D025341:Principal Component Analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000502:physiology; D013003:Somatosensory Cortex / Q000166:cytology* / Q000502:physiology*; D013223:Statistics as Topic; D014738:Vibrissae / Q000294:innervation*
keywords: barrel cortex; multi-site recording; sensory funneling; stimulus invariance; whisker array