Traumatic Brain Injury-Induced Fear Generalization in Mice Involves Hippocampal Memory Trace Dysfunction and Is...

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Memory and Cognition

Background:

• Traumatic brain injury (TBI) is a significant cause of neurological damage.
• TBI can lead to persistent cognitive deficits, notably fear generalization, impairing stimulus discrimination.
• Current therapeutic options for TBI-induced fear generalization are limited.

Purpose of the Study:

• To investigate the neural mechanisms underlying fear generalization following TBI.
• To identify specific neural ensembles involved in TBI-related fear memory.
• To evaluate the efficacy of (R,S)-ketamine in mitigating fear generalization in TBI models.

Main Methods:

• Utilized ArcCreER^T2 × EYFP mice for activity-dependent neural ensemble labeling.
• Employed the controlled cortical impact model to induce TBI in mice.
• Assessed fear generalization using a contextual fear discrimination paradigm and quantified memory traces in key brain regions.
• Administered (R,S)-ketamine to TBI mice to assess its effects on behavior and neural activity.

Main Results:

• TBI mice demonstrated significantly increased fear generalization compared to sham controls.
• Altered memory traces were observed in the dentate gyrus, CA3, and amygdala of TBI mice.
• (R,S)-ketamine treatment improved fear discrimination in TBI mice, correlating with normalized dentate gyrus memory trace activity.

Conclusions:

• TBI induces fear generalization through modifications in fear memory traces.
• A single administration of (R,S)-ketamine can ameliorate TBI-induced fear generalization.
• This study provides insights into the neural underpinnings of TBI-related fear generalization and highlights ketamine as a potential therapeutic agent.