Neural tracking of speech mental imagery during rhythmic inner counting

Abstract

The subjective inner experience of mental imagery is among the most ubiquitous human experiences in daily life. Elucidating the neural implementation underpinning the dynamic construction of mental imagery is critical to understanding high-order cognitive function in the human brain. Here, we applied a frequency-tagging method to isolate the top-down process of speech mental imagery from bottom-up sensory-driven activities and concurrently tracked the neural processing time scales corresponding to the two processes in human subjects. Notably, by estimating the source of the magnetoencephalography (MEG) signals, we identified isolated brain networks activated at the imagery-rate frequency. In contrast, more extensive brain regions in the auditory temporal cortex were activated at the stimulus-rate frequency. Furthermore, intracranial stereotactic electroencephalogram (sEEG) evidence confirmed the participation of the inferior frontal gyrus in generating speech mental imagery. Our results indicate that a disassociated neural network underlies the dynamic construction of speech mental imagery independent of auditory perception.

Cortical Correlates of Gait Compensation Strategies in Parkinson Disease

“…Compared to uncued gait, the application of external cueing, internal cueing, and action observation during gait resulted in spectral power changes over sensorimotor, frontal, parietal, and occipital cortical areas, which is in agreement with previous findings of walking under goal‐directed conditions (eg, following internal or external cues). 33 , 36 In contrast to earlier work, we were able to confirm that the altered cortical activation we found was not merely attributable to increased cortical recruitment due to processing sensory input related to the cueing modality (ie, listening to a metronome, 37 watching another person walking 38 ) or engaging in a cognitive task (such as rhythmic counting 39 ). By including control conditions during stance (during which the same compensation strategies were applied) into our experimental protocol, we were able to correct for the stimulus‐related cortical activity, and consequently distil the cortical activation patterns that were most likely contributing to gait control.…”

Neural Signatures of Hierarchical Linguistic Structures in Second Language Listening Comprehension

“…Future research with larger sample sizes and increased statistical power will for allow more representative sampling and thorough investigation of how the listener's L1 experience (for example, with different preferred word orders) influences L2 speech comprehension. Second, we adopted a previously developed paradigm of concurrent neural tracking (Ding et al, 2016(Ding et al, , 2017(Ding et al, , 2018Makov et al, 2017;Lu et al, 2019Lu et al, , 2021Blanco-Elorrieta et al, 2020), in which the neural responses to hierarchical linguistic structures were simultaneously tagged at different frequencies. Since this paradigm risks contamination from harmonics on the tracking responses, separate conditions of linguistic structures (Sheng et al, 2019;Gui et al, 2020) should be considered in future neural tracking studies.…”

Studying rhythm processing in speech through the lens of auditory-motor synchronization

“…The finger-tapping task externalizes internal rhythms, with or without an external pacemaker. Constructing imagined rhythm requires the engagement of higher-order brain function in which auditory mental imagery is formed and accurately organized (Lu et al, 2019(Lu et al, , 2021. Thus, studying finger-tapping to imagined rhythms could shed light on the top-down mechanisms in encoding and maintaining the hierarchical rhythms.…”