Interhemispheric transfer deficit in alexithymia: a transcranial magnetic stimulation study

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Alexithymia, a personality trait characterized by difficulty identifying and describing emotions, has been hypothesized to involve interhemispheric transfer deficits.
• Previous research noted alexithymic features in split-brain patients, suggesting impaired communication between brain hemispheres.
• Direct evidence for interhemispheric transfer deficits in alexithymia has been lacking.

Purpose of the Study:

• To investigate the hypothesis of a transcallosal interhemispheric transfer deficit in individuals with alexithymia.
• To explore functional differences in interhemispheric communication in high alexithymia.

Main Methods:

• Screened 300 students for alexithymia using the Toronto Alexithymia Scale.
• Selected high and low alexithymia groups (8 males, 8 females each).
• Utilized paired-pulse transcranial magnetic stimulation to assess transcallosal inhibition between motor cortices.

Main Results:

• High alexithymia subjects demonstrated significantly reduced transcallosal inhibition compared to low alexithymia subjects.
• This reduction was observed in both left-to-right and right-to-left interhemispheric transfer directions.
• Specific interstimulus intervals (10, 12, 14 ms) revealed significant differences.

Conclusions:

• The findings support the hypothesis of an interhemispheric transfer deficit in alexithymia.
• Results indicate functional differences in transcallosal interactions in high alexithymia.
• This study provides direct evidence for impaired brain hemisphere communication in alexithymia.