Impaired fear processing in right mesial temporal sclerosis: a fMRI study

Area of Science:

• Neuroscience
• Neurology
• Psychology

Background:

• The mesial temporal lobe is vital for recognizing emotions from facial expressions.
• Bilateral amygdala damage impairs fear recognition.
• Unilateral mesial temporal lobe damage effects on facial emotion recognition are less understood.

Purpose of the Study:

• To investigate the impact of unilateral mesial temporal lobe damage on facial expression recognition.
• To examine functional magnetic resonance imaging (fMRI) brain activation during fearful face processing in mesial temporal lobe epilepsy (MTLE) patients.
• To assess the influence of seizure onset age (early vs. late) on these deficits.

Main Methods:

• Thirteen MTLE patients (8 right, 5 left) and 14 healthy controls underwent neuropsychological testing and fMRI.
• Participants incidentally processed fearful faces.
• Patients were categorized by seizure onset age (hippocampal-amygdalar sclerosis with onset before age 5 vs. late onset).

Main Results:

• Right MTLE patients showed impaired recognition of fearful facial expressions.
• Early-onset seizures correlated with the most severe recognition deficits.
• Impaired recognition was associated with altered activation in neural networks for fear processing, including the left inferior frontal cortex and occipito-temporal regions.

Conclusions:

• Unilateral right mesial temporal lobe damage impairs fear recognition.
• Early-onset epilepsy exacerbates these deficits.
• Deficits are linked to disrupted functional brain networks involved in processing fearful facial expressions.