Electrophysiological study of the basal temporal language area: a convergence zone between language perception and production networks.

OBJECTIVE: Regions involved in language processing have been observed in the inferior part of the left temporal lobe. Although collectively labelled 'the Basal Temporal Language Area' (BTLA), these territories are functionally heterogeneous and are involved in language perception (i.e. reading or semantic task) or language production (speech arrest after stimulation). The objective of this study was to clarify the role of BTLA in the language network in an epileptic patient who displayed jargonaphasia.
METHODS: Intracerebral evoked related potentials to verbal and non-verbal stimuli in auditory and visual modalities were recorded from BTLA. Time-frequency analysis was performed during ictal events.
RESULTS: Evoked potentials and induced gamma-band activity provided direct evidence that BTLA is sensitive to language stimuli in both modalities, 350 ms after stimulation. In addition, spontaneous gamma-band discharges were recorded from this region during which we observed phonological jargon.
CONCLUSION: The findings emphasize the multimodal nature of this region in speech perception. In the context of transient dysfunction, the patient's lexical semantic processing network is disrupted, reducing spoken output to meaningless phoneme combinations. SIGNIFICANCE: This rare opportunity to study the BTLA "in vivo" demonstrates its pivotal role in lexico-semantic processing for speech production and its multimodal nature in speech perception.