# Transient selective aphasia in highly proficient bilinguals triggered by electrical stimulation of the left superior temporal gyrus

## TL;DR

This study shows that first and second languages in bilinguals are represented in both shared and distinct areas of the brain.

## Contribution

The study identifies distinct language representations in the left temporal lobe using intraoperative mapping in bilingual patients.

## Key findings

- Stimulation of the posterior and anterior superior temporal gyri caused language-selective aphasias.
- Mid-temporal and inferior fronto-occipital fasciculus stimulation led to non-specific naming errors.
- The findings reveal both shared and distinct loci for L1 and L2 in the bilingual brain.

## Abstract

Are an individual’s first (L1) and second (L2) languages represented in shared or distinct brain territories? Using intraoperative electrical stimulation mapping (ESM) in two Basque-Spanish bilinguals with non-growing lesions—thus avoiding confounding effects of adaptive plasticity—this study identified distinct language representations within the left temporal lobe. Stimulation of posterior and anterior superior temporal gyri induced language-selective aphasias, whereas stimulation of the mid-temporal region and inferior fronto-occipital fasciculus produced naming errors without language specificity. These findings highlight both shared and distinct loci for L1 and L2, advancing our understanding of bilingual brain organization.

The online version contains supplementary material available at 10.1007/s00701-025-06508-5.