Evaluation of implantable multi-channel neuroprobe based on neuronal activities among layers of the primary somatosensory cortex of the rat
Date Issued
2012
Date
2012
Author(s)
Chang, Chia-Ming
Abstract
Presently, electrophysiological studies focus primarily on recording and analyzing signals while testing animals are in conscious state. New research suggests the idea that differences in state of brain as well as type of anesthetics could result in different activity of neurons. In addition, some research studies point out the limitations of doing animal testing under states of anesthesia since higher brain function will be inhibited at the time. Thus research animals should be maintained consciousness. The purpose of this study is to design a protocol of electrophysiological study with animals in conscious states and evaluate the feasibility of applying implantable multi-channel neuroprobe in future studies.
In this study, signals were recorded from hindpaw region of the primary somatosensory cortex (S1) in adult rats. Due to the response properties of neurons in primary somatosensory cortex and the conformation of multi-channel neuroprobe, the responses to mechanical stimuli of neurons were recorded in same column, however, in different laminar in order to evaluate the usability of the implantable multi-channel neuroprobe.
After implantation, the changes of evoked action potential were examined for three months. The results recorded were analyzed in three different ways: (1) amplitude of signals; (2) latency of evoked action potential; and (3) statistical analysis on layers. First of all, although the decline was different in laminar, the amplitude of the signal was found becoming smaller over time. Additionally, the probability of signal overlap increased. Secondly, regarding to the latency of evoked action potential, in long-term recording, the shortest one was found in layer IV which corresponded to the previous studies. Last but not least, there was a declining trend of signal integration in laminar, and the greatest decline was in layer V. Moreover, in long-term recording, the differences between the activity of layer II/III and layer IV could be distinguished utilizing statistical analysis. Therefore, although neuroprobe would influence the activity of neurons after implantation, it could be utilized to record signals for analysis. Furthermore, since there are multi-channels in one neuroprobe, this will be the superiority on studying differences in activity in S1 laminar with animals in conscious states.
Subjects
conscious state
long-tern recording
implantable multi-channel neuroprobe
primary somatosensory cortex
touch
hindpaw
Type
thesis
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