Persistent working memory dysfunction following traumatic brain injury: evidence for a time-dependent mechanism

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Cognitive Function

Background:

• Traumatic brain injury (TBI) frequently impairs prefrontal cortex functions, including working memory.
• Working memory deficits post-TBI can occur without obvious prefrontal cortex damage.
• Excess GABA-mediated inhibition is a known early contributor to post-TBI working memory dysfunction.

Purpose of the Study:

• To investigate if working memory deficits persist long-term after TBI.
• To determine if persistent deficits are treatable by GABA antagonism.
• To elucidate the underlying mechanisms of chronic working memory dysfunction post-TBI.

Main Methods:

• Lateral cortical impact injury in rats.
• Assessment of working memory using delay match-to-place and delayed alternation T-maze tasks.
• Golgi staining to analyze neuronal morphology (dendrite arbors and spine density).
• Electrophysiological assessment of GABA-mediated inhibition.

Main Results:

• Working memory deficits persisted for at least 16 weeks post-TBI.
• GABA receptor antagonists did not improve working memory at 16 weeks post-TBI.
• TBI induced significant dendritic and spine density changes in prelimbic pyramidal neurons by 4 months post-injury, but not at 14 days.
• Excess GABA-mediated inhibition was not the cause of chronic deficits.

Conclusions:

• Working memory dysfunction following TBI is a persistent issue.
• The mechanisms driving chronic working memory deficits differ from acute ones.
• Therapeutic strategies for TBI-related working memory impairment must consider the temporal evolution of the injury and its underlying neural changes.