Transition from Initial Hypoactivity to Hyperactivity in Cortical Layer v Pyramidal Neurons after Traumatic Brain Injury in Vivo

Xingjie Ping, Xiaoming Jin

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

Traumatic brain injury (TBI) often results in structural damage and a loss of neurons that is commonly accompanied by early changes in neuronal electrical activity. Loss of neuronal activity has been hypothesized to contribute to post-traumatic epileptogenesis through the regulation of homeostatic plasticity. The existence of activity loss in cortical neurons after TBI and its subsequent transition into hyperactivity over time is not well characterized, however, particularly in models of TBI in vivo. In the current study, changes in neuronal activity in the primary motor cortex after moderate controlled cortical impact (CCI) in mice were studied using a single-unit recording technique in vivo. Recordings were made at different time points after CCI from cortical layer V pyramidal neurons that were within 1-2 mm from the anterior edge of the injured foci. Within 1-4 h after CCI, the frequency of spontaneous single-unit activity depressed significantly, with the mean firing frequency decreasing from 2.59 0.18 Hz in the sham group to 1.05 0.20 Hz of the injured group. The firing frequencies recovered to the normal level at 1 day and 7 days post-CCI, but became significantly higher at 3 days and 14 days post-CCI. The results suggest that TBI caused initial loss of activity in neurons of the perilesional cortical region, which was followed by compensatory recovery and enhancement of activity. These time-dependent changes in neuronal activity may contribute to the development of hyperexcitability through homeostatic activity regulation.

Original languageEnglish (US)
Pages (from-to)354-361
Number of pages8
JournalJournal of Neurotrauma
Volume33
Issue number4
DOIs
StatePublished - Feb 15 2016

Keywords

  • action potential
  • neuronal activity
  • post-traumatic epilepsy
  • single-unit recording
  • traumatic brain injury

ASJC Scopus subject areas

  • Clinical Neurology

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