Ensemble Recording in Rat Somatosensory Cortex for Laminar Activities of Touch and First Component of Nociception
Date Issued
2012
Date
2012
Author(s)
Kao, Yu-Chieh
Abstract
The understanding of cortical microcircuits was traditionally based on the anatomical province, including cytoarchitecture, connections between nuclei, and the relationship to peripheral receptive fields. In this study, with insight into their responses to different sensory modalities, we explore the columnar and laminar functions in the hindpaw region of the primary somatosensory cortex (S1) in the rat.
The 16-channel neural probe was used in this study to simultaneously acquire the neural responses among laminae in a column. High-frequency multi-unit activities (MUAs), as well as low-frequency field potentials (FPs), were recorded and filtered. Rectification and integration for MUAs and current-source-density analysis for FPs were performed to quantitatively analyze their responses respectively. Furthermore, to study the responses of the same column to different modalities, not only non-noxious mechanical stimuli, but also noxious CO2 laser stimuli were delivered to the same receptive field on the hindpaw of the rat.
The results demonstrate that S1 of the rat is actually involved in the processing of nociception, because of the constant latency characteristics of the laser-evoked MUAs and FPs. Comparing non-nociceptive and nociceptive responses in the same column, laminar functions of cortical columns could be examined. The layer Ⅳ and the superficial layer Ⅴ with consistent higher activities, no matter which modality was applied to the periphery, receive the thalamocortical projection, while the superficial cortical lamina, the layer Ⅱ/Ⅲ, just processes innocuous input. The parallel coding of different sensory modalities in a single column further corroborates the columnar organization in S1 and implies the idea that the functional role of a column might depend on the number of cortical columns among different species.
Subjects
Multi-unit activity
field potentials
rectification and integration
current source density
CO2 laser
hindpaw
Type
thesis
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