Functional MRI Investigation of Memory and Language in Temporal Lobe Epilepsy

Abstract

Purpose: Language and memory impairments are common in patients with temporal lobe epilepsy (TLE). Precise identification of language and memory areas is crucial for both identifying the seizure zone and predicting the preservation or recovery of cognitive functions after brain surgery. Functional MRI (fMRI), with its unique ability to elucidate the brain's compensatory mechanisms in response to epilepsy, aids in visualizing brain activity and reveals how different parts of the brain have adapted.

Methods: We conducted a study on 22 left TLE and 13 right TLE patients, as well as 17 healthy control subjects, using task-based fMRI for memory and language mapping. This was done to examine the effective areas responsible for language and memory functions and detect abnormal activations. All participants underwent the CANTAB® neuropsychological test.

Results: We discovered a significant increase in the participation of the left temporal lobe and parahippocampal gyrus in the encoding of non-verbal memory, and increased activation in the left precuneus and right parahippocampal gyrus during the retrieval of non-verbal memory (P < 0.05). In verbal memory tasks, increased participation of the frontal lobes in the encoding and retrieval of verbal memory, along with a significant contribution from the left cingulate gyrus during memory retrieval, indicates compensatory mechanisms (P < 0.05).

Conclusions: Our findings suggest that, compared to healthy controls, TLE patients exhibited activation in more diverse brain regions during language tasks, yet achieved similar functional test results.