Speech Processing in Cochlear-Implant Patients: Results of Corresponding EEG and Brain Perfusion-SPECT Measurements

Introduction:

The current study examines the underlying mechanisms of speech processing in CI patients using a multimodal approach. Data are collected by single photon emission tomography (SPECT) and electroencephalography (EEG).

Methods:

So far, 16 post-lingually deafened CI patients (59.8 ± 12 years, 9 f) participated in the study with two sessions. One session includes a task in which sentences are classified as semantically correct or incorrect. During the task, a 96-channel EEG is being recorded. Two minutes after the start of the task, 740 MBq of 99mTc-HMPAO are injected intravenously. A SPECT scan 1.5 hours after injection shows the cortical activity during the task. A second session includes a SPECT scan after injection at rest.

Results:

The first results show bilateral activation of the auditory cortex during the task. A larger N400 (EEG) is associated with greater activity in temporal areas (Brodmann area (BA) 20, left). Better working memory is associated with greater activity in Broca's area, premotor cortex, as well as in auditory and frontal areas (BA8, left). Poor CI performers show a stronger activation of Broca's area, parietal (BA40/2, left), frontal (BA8) and prefrontal areas (BA9/46), as well as in premotor cortex (left). In contrast, good CI performers show greater activity in auditory and temporal regions (BA20/38).

Conclusion:

Combined SPECT/EEG measurements in the context of a speech processing task show the recruitment of a temporo-frontal network with good and bad CI performers showing different activation patterns. Correlations were shown between SPECT/EEG, speech data and cognitive data.

Publication History

Publication Date:
23 April 2019 (online)