Acute Cortical Transhemispheric Diaschisis after Unilateral Traumatic Brain Injury

Area of Science:

• Neuroscience
• Traumatic Brain Injury Research
• Cortical Plasticity

Background:

• Focal brain injuries cause widespread functional changes, including in the undamaged hemisphere (transhemispheric diaschisis).
• Understanding early transhemispheric changes is vital for deciphering brain injury pathophysiology and recovery.
• Little is known about acute-subacute (24-48h) changes in the hemisphere contralateral to injury.

Purpose of the Study:

• Investigate early (24-48h) transhemispheric functional alterations after unilateral traumatic brain injury (TBI).
• Elucidate the role of the undamaged hemisphere in early functional reorganization post-TBI.

Main Methods:

• Induced unilateral TBI in mice via controlled cortical impact targeting motor and somatosensory cortex.
• Performed in vitro extracellular multi-unit and single-cell patch-clamp recordings in the contralateral cortical network.
• Analyzed neuronal activity, intrinsic properties, and GABAergic transmission.

Main Results:

• Observed transient neuronal hyperactivity in the intact hemisphere 24-48h post-TBI.
• Found no alterations in neuronal intrinsic properties.
• Detected impaired phasic GABAergic transmission and increased GABA A receptor subunits related to tonic inhibition in the contralateral hemisphere.

Conclusions:

• Early transhemispheric functional alterations occur within 24-48h after unilateral cortical injury.
• These changes, including neuronal hyperactivity and altered GABAergic signaling, may compensate for disrupted functions.
• The undamaged hemisphere plays a significant role in early functional reorganization processes following TBI.