Spatio-temporal dynamics of working memory maintenance and scanning of verbal information

作者：Kambara Toshimune; Brown Erik C; Jeong Jeong Won; Ofen Noa; Nakai Yasuo; Asano Eishi^*

来源：Clinical Neurophysiology, 2017, 128(6): 882-891.

DOI：10.1016/j.clinph.2017.03.005

• High-frequency oscillations (HFOs)
• Subdural electroencephalography (EEG)
• Intracranial electrocorticography (ECoG) recording
• Pediatric epilepsy surgery
• Sternberg paradigm
• 4D brain mapping

Objective: During verbal communication, humans briefly maintain mental representations of speech sounds conveying verbal information, and constantly scan these representations for comparison to incoming information. We determined the spatio-temporal dynamics of such short-term maintenance and subsequent scanning of verbal information, by intracranially measuring high-gamma activity at 70-110 Hz during a working memory task.
Methods: Patients listened to a stimulus set of two or four spoken letters and were instructed to remember those letters over a two-second interval, following which they were asked to determine if a subsequent target letter had been presented earlier in that trial's stimulus set.
Results: Auditory presentation of letter stimuli sequentially elicited high-gamma augmentation bilaterally in the superior-temporal and pre-central gyri. During the two-second maintenance period, high-gamma activity was augmented in the left pre-central gyrus, and this effect was larger during the maintenance of stimulus sets consisting of four compared to two letters. During the scanning period following target presentation, high-gamma augmentation involved the left inferior-frontal and supra-marginal gyri.
Conclusions: Short-term maintenance of verbal information is, at least in part, supported by the left precentral gyrus, whereas scanning by the left inferior-frontal and supra-marginal gyri.
Significance: The cortical structures involved in short-term maintenance and scanning of speech stimuli were segregated with an excellent temporal resolution.

• 出版日期2017-6