title: Rate and Temporal Coding Convey Multisensory Information in Primary Sensory Cortices.
abstract: Optimal behavior and survival result from integration of information across sensory systems. Modulation of network activity at the level of primary sensory cortices has been identified as a mechanism of cross-modal integration, yet its cellular substrate is still poorly understood. Here, we uncover the mechanisms by which individual neurons in primary somatosensory (S1) and visual (V1) cortices encode visual-tactile stimuli. For this, simultaneous extracellular recordings were performed from all layers of the S1 barrel field and V1 in Brown Norway ratsin vivoand units were clustered and assigned to pyramidal neurons (PYRs) and interneurons (INs). We show that visual-tactile stimulation modulates the firing rate of a relatively low fraction of neurons throughout all cortical layers. Generally, it augments the firing of INs and decreases the activity of PYRs. Moreover, bimodal stimulation shapes the timing of neuronal firing by strengthening the phase-coupling between neuronal discharge and theta-beta band network oscillations as well as by modulating spiking onset. Sparse direct axonal projections between neurons in S1 and V1 seem to time the spike trains between the two cortical areas and, thus, may act as a substrate of cross-modal modulation. These results indicate that few cortical neurons mediate multisensory effects in primary sensory areas by directly encoding cross-modal information by their rate and timing of firing.
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf , Hamburg 20251, Germany.
authors.forename: Malte
authors.identifier: 0000-0001-5685-0109
authors.initials: M
authors.lastname: Bieler
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf , Hamburg 20251, Germany.
authors.forename: Kay
authors.initials: K
authors.lastname: Sieben
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf , Hamburg 20251, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Cichon
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf , Hamburg 20251, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Schildt
authors.affiliation: Biological Psychology and Neuropsychology, University Hamburg , Hamburg 20146, Germany.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Röder
authors.affiliation: Developmental Neurophysiology, Institute of Neuroanatomy, University Medical Center Hamburg-Eppendorf , Hamburg 20251, Germany.
authors.forename: Ileana L
authors.initials: IL
authors.lastname: Hanganu-Opatz
mesh_terms: D000200:Action Potentials; D000818:Animals; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism; D007395:Interneurons / Q000166:cytology / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D017966:Pyramidal Cells / Q000166:cytology / Q000502:physiology*; D051381:Rats; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology; D013997:Time Factors; D055698:Touch Perception / Q000502:physiology*; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*
chemical_list: D018698:Glutamic Acid
keywords: barrel field; multisensory; neuronal firing; oscillation; primary visual cortex; rate coding; temporal coding 