Functional substrate for memory function differences between patients with left and right mesial temporal lobe...

Area of Science:

• Neuroscience
• Epilepsy Research
• Cognitive Electrophysiology

Background:

• Mesial temporal lobe epilepsy (mTLE) with hippocampal sclerosis (HS) significantly impacts memory function.
• Electrophysiological differences underlying memory deficits in left vs. right mTLE remain poorly understood.

Purpose of the Study:

• To investigate resting-state hippocampal theta connectivity as a functional substrate for memory differences in patients with left or right mTLE and HS.
• To correlate electrophysiological findings with memory performance.

Main Methods:

• Whole-brain magnetoencephalography (MEG) was used to assess resting-state hippocampal theta connectivity.
• Connectivity and memory function were compared between 41 mTLE with HS patients (22 left, 19 right), 46 healthy controls, and 28 focal cortical dysplasia (FCD) patients.

Main Results:

• Right mTLE patients exhibited stronger theta connectivity between the right hippocampus and left middle frontal gyrus compared to left mTLE patients and FCD patients.
• This connectivity positively correlated with delayed verbal recall and recognition scores.
• Left mTLE patients showed greater impairments in delayed recall and recognition than right mTLE and FCD patients.

Conclusions:

• Right hippocampal-left middle frontal theta connectivity may explain memory function disparities between left and right mTLE patients.
• This connectivity pattern might reflect distinct compensatory mechanisms against hippocampal lesions.
• Hemispheric-specific hippocampal-frontal theta connectivity assessment could serve as an electrophysiological indicator for delayed verbal memory function in mTLE with HS.