Right hemisphere ventral stream for emotional prosody identification

Objective To determine whether right ventral stream and limbic structures (including posterior superior temporal gyrus [STG], STG, temporal pole, inferior frontal gyrus pars orbitalis, orbitofrontal cortex, amygdala, anterior cingulate, gyrus, and the sagittal stratum) are implicated in emotional prosody identification.

Methods Patients with MRI scans within 48 hours of unilateral right hemisphere ischemic stroke were enrolled. Participants were presented with 24 sentences with neutral semantic content spoken with happy, sad, angry, afraid, surprised, or bored prosody and chose which emotion the speaker was feeling based on tone of voice. Multivariable linear regression was used to identify individual predictors of emotional prosody identification accuracy from a model, including percent damage to proposed right hemisphere structures, age, education, and lesion volume across all emotions (overall emotion identification) and 6 individual emotions. Patterns of recovery were also examined at the chronic stage.

Results The overall emotion identification model was significant (adjusted r² = 0.52; p = 0.043); greater damage to right posterior STG (p = 0.038) and older age (p = 0.009) were individual predictors of impairment. The model for recognition of fear was also significant (adjusted r² = 0.77; p = 0.002), with greater damage to right amygdala (p = 0.047), older age (p < 0.001), and less education (p = 0.005) as individual predictors. Over half of patients with chronic stroke had residual impairments.

Conclusions Right posterior STG in the right hemisphere ventral stream is critical for emotion identification in speech. Patients with stroke with damage to this area should be assessed for emotion identification impairment.