Journal: Journal of Neurotrauma

Article Title: Mild Traumatic Brain Injury Decreases Spatial Information Content and Reduces Place Field Stability of Hippocampal CA1 Neurons

doi: 10.1089/neu.2019.6766

Figure Lengend Snippet: Experimental timeline for surgery and object location task paradigm. (A) Timeline showing the time of injury, electrode implantation, and cognitive testing. Rats received either sham surgery or mild lateral fluid percussion injury (mFPI), and on day 7 post-injury, a 32 electrode array was stereotaxically placed into the cornu Ammonis (CA)1 of the dorsal hippocampus ipsilateral to the injury. During the electrode placement, recordings were made to detect neurophysiological ripples of the CA1 pyramidal cell layer. (B) Rats were first habituated to an empty arena containing positional cues on the walls (20 min/day for 3 days). During habituation, the rats were exposed to the arena in the absence of any on-ground objects. During familiarization, rats were allowed to explore two identical objects for 10 min, after which they were placed in a holding box for a 5 min inter-trial interval. During testing, one of the objects was moved to a new location in the box and the animals were allowed to explore for 5 min. Electrophysiological recordings were made and infrared tracking of the head was performed during both the familiarization and testing periods.

Article Snippet: In the present study, we recorded hippocampal CA1 neuronal activity from sham and lateral mild fluid percussion injury (mFPI) animals while the animals were performing an object location task.

Techniques:

Journal: Journal of Neurotrauma

Article Title: Mild Traumatic Brain Injury Decreases Spatial Information Content and Reduces Place Field Stability of Hippocampal CA1 Neurons

doi: 10.1089/neu.2019.6766

Figure Lengend Snippet: Mild lateral fluid percussion injury (mFPI) causes loss of parvalbumin-positive inhibitory neurons in the ipsilateral cornu Ammonis (CA)1 subfield. To assess the histological consequences of mFPI, separate groups of rats (n = 3/group) received either a sham or mFPI surgery but were not implanted with electrodes. (A) Representative montaged photomicrographs of brain sections from a 14 day post-surgery sham and a 14 day post-injury mFPI animal stained with bisbinzimide (pseudo-colored green for maximum visibility). No overt damage or cell loss was observed, consistent with a mild injury magnitude. (B) Representative photomicrograph showing neuronal nuclei (NeuN) (top panels) and microtubule associated protein 2 (MAP2) (bottom panels) immunoreactivity in the dorsal, ipsilateral hippocampus of a sham and an mFPI rat. (C) Confocal images of NeuN and MAP2 immunostaining from the CA1 region (illustrated by the box in panel B) showing no overt cell loss or dendritic disruptions. (D) Representative photomicrograph showing parvalbumin immunoreactivity in the dorsal, ipsilateral hippocampus of a sham and an mFPI rat. (E) Quantification of the number of parvalbumin-positive cells in the pyramidal layer of the CA1.

Article Snippet: In the present study, we recorded hippocampal CA1 neuronal activity from sham and lateral mild fluid percussion injury (mFPI) animals while the animals were performing an object location task.

Techniques: Staining, Immunostaining