The role of the insula in speech and language processing

• Insular involvement in speech and language processing was examined.
• Activation Likelihood Estimation (ALE) meta-analyses were conducted on fMRI data.
• Language and speech stimuli activated similar regions of bilateral anterior insula.
• Left dorsal mid-insula activation was associated with speech perception.
• Insular cortex shows regional differences for speech and language functions.

Lesion and neuroimaging studies indicate that the insula mediates motor aspects of speech production, specifically, articulatory control. Although it has direct connections to Broca’s area, the canonical speech production region, the insula is also broadly connected with other speech and language centres, and may play a role in coordinating higher-order cognitive aspects of speech and language production. The extent of the insula’s involvement in speech and language processing was assessed using the Activation Likelihood Estimation (ALE) method. Meta-analyses of 42 fMRI studies with healthy adults were performed, comparing insula activation during performance of language (expressive and receptive) and speech (production and perception) tasks. Both tasks activated bilateral anterior insulae. However, speech perception tasks preferentially activated the left dorsal mid-insula, whereas expressive language tasks activated left ventral mid-insula. Results suggest distinct regions of the mid-insula play different roles in speech and language processing.