title: Cortical and thalamic contributions to response dynamics across layers of the primary somatosensory cortex during tactile discrimination.
abstract: Tactile information processing in the rodent primary somatosensory cortex (S1) is layer specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the primary somatosensory cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), whereas the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (POM). Selective inactivation of contralateral S1 specifically switched infragranular neural dynamics from POM-like to those resembling VPM neurons. Meanwhile, ipsilateral M1 inactivation profoundly modulated the firing suppression observed in infragranular layers. This latter effect was counterbalanced by contralateral S1 block. Tactile stimulus encoding was layer specific and selectively affected by M1 or contralateral S1 inactivation. Lastly, causal information transfer occurred between all neurons in all S1 layers but was maximal from infragranular to the granular layer. These results suggest that tactile information processing in the S1 of awake behaving rodents is layer specific and state dependent and that its dynamics depend on the asynchronous convergence of modulations originating from ipsilateral M1 and contralateral S1.
authors.affiliation: Department of Neurobiology, Duke University, Durham, North Carolina; Center for Neuroengineering, Duke University, Durham, North Carolina; and.
authors.forename: Miguel
authors.initials: M
authors.lastname: Pais-Vieira
authors.affiliation: Edmond and Lily Safra International Institute for Neuroscience of Natal, Natal, Brazil.
authors.forename: Carolina
authors.initials: C
authors.lastname: Kunicki
authors.affiliation: Department of Neurobiology, Duke University, Durham, North Carolina;
authors.forename: Po-He
authors.initials: PH
authors.lastname: Tseng
authors.affiliation: Department of Neurobiology, Duke University, Durham, North Carolina;
authors.forename: Joel
authors.initials: J
authors.lastname: Martin
authors.affiliation: Department of Neurobiology, Duke University, Durham, North Carolina; Center for Neuroengineering, Duke University, Durham, North Carolina; and.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Lebedev
authors.affiliation: Department of Neurobiology, Duke University, Durham, North Carolina; Department of Biomedical Engineering, Duke University, Durham, North Carolina; Department of Psychology and Neuroscience, Duke University, Durham, North Carolina; Center for Neuroengineering, Duke University, Durham, North Carolina; and Edmond and Lily Safra International Institute for Neuroscience of Natal, Natal, Brazil nicoleli@neuro.duke.edu.
authors.forename: Miguel A L
authors.initials: MA
authors.lastname: Nicolelis
mesh_terms: D000818:Animals; D004192:Discrimination, Psychological; D005260:Female; D009474:Neurons / Q000166:cytology; D020656:Posterior Thalamic Nuclei / Q000166:cytology / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology*; D055698:Touch Perception
keywords: barrel cortex; cortical loop modulations; dynamics; thalamocortical loop