Abstracts

Rationale: One can readily identify and name an object based on its looks, sounds, or descriptive sentence. Though any naming tasks are expected to activate the left perisylvian cortices, it remains under-reported how well naming tasks share the spatiotemporal characteristics of naming-related frontal lobe activation. We determined if naming-related cortical modulations differed between picture and non-speech environmental sound stimuli. We then determined if cortical modulations differed between non-speech environmental and spoken sentence sound stimuli.

Methods: We studied 13 children (age: 6-19 years) who underwent epilepsy surgery following extraoperative intracranial EEG (iEEG) recording at Children’s Hospital of Michigan, Detroit, between 2015 and 2018. Each patient underwent naming tasks during the iEEG recording. The stimuli consisted of either picture, environmental sounds (e.g., a meow sound), or spoken sentence sounds (e.g., ‘What flies in the sky?’). We generated a four-dimensional dynamic atlas animating when and where the high-gamma amplitude (at 70-110 Hz) was increased or decreased. The mixed model analysis determined when and where the high-gamma amplitude differed between the tasks.

Results: There was a double dissociation in naming-related high-gamma activation sites between the visual and auditory stimuli. Within 100 ms after stimulus onset, picture stimuli induced greater high-gamma augmentation in the ventral occipital-temporal regions, whereas environmental sounds in the superior temporal gyri (STG). Within 150 ms after stimulus onset, such sounds induced greater high-gamma augmentation in the left precentral gyrus. A double dissociation was also noted in high-gamma activation sites between the environmental and spoken sentence sounds. Within 200 ms after stimulus onset, environmental sounds induced greater high-gamma augmentation in the posterior STG, whereas spoken sentence sounds in the anterior STG. Within 500 ms after stimulus onset, environmental sounds induced greater high-gamma augmentation in the left inferior frontal gyrus (IFG). Between the sound offset and response onset, sentence-based naming induced greater high-gamma augmentation in the left posterior middle frontal gyrus (MFG).

Conclusions: Environmental sounds may activate the phonological loop involving the left precentral gyrus within 150 ms and facilitate the lexical retrieval process in the left IFG within 500 ms. Sentence-based naming may require the function of the left posterior MFG more than naming based on the sound features not requiring syntactic processing. This observation is consistent with the notion that high-gamma measurement during auditory sentence-based naming may maximize the localization of naming-related areas in the left MFG.

Funding: Please list any funding that was received in support of this abstract.: NIH grant NS64033.