Swallowing‐related neural oscillation: an intracranial EEG study

Abstract

Objective: Swallowing is a unique movement due to the indispensable orchestration of voluntary and involuntary movements. The transition from voluntary to involuntary swallowing is executed within milliseconds. We hypothesized that the underlying neural mechanism of swallowing would be revealed by high-frequency cortical activities. Methods: Eight epileptic participants fitted with intracranial electrodes over the orofacial cortex were asked to swallow a water bolus and cortical oscillatory changes, including the high c band (75-150 Hz) and b band (13-30 Hz), were investigated at the time of mouth opening, water injection, and swallowing. Results: Increases in high c power associated with mouth opening were observed in the ventrolateral prefrontal cortex (VLPFC) with water injection in the lateral central sulcus and with swallowing in the region along the Sylvian fissure. Mouth opening induced a decrease in b power, which continued until the completion of swallowing. The high c burst of activity was focal and specific to swallowing; however, the b activities were extensive and not specific to swallowing. In the interim between voluntary and involuntary swallowing, swallowing-related high c power achieved its peak, and subsequently, the power decreased. Interpretation: We demonstrated three distinct activities related to mouth opening, water injection, and swallowing induced at different timings using high c activities. The peak of high c power related to swallowing suggests that during voluntary swallowing phases, the cortex is the main driving force for swallowing as opposed to the brain stem.

Motor and sensory cortical processing of neural oscillatory activities revealed by human swallowing using intracranial electrodes

“…The cortex may trigger swallowing and modulate the brainstem (Ertekin and Aydogdu, 2003), and HG activities appeared in the cortex during the voluntary swallowing phase rather than during the involuntary swallowing phase (Hashimoto et al, 2021b). These findings support that the cooperation between voluntary and involuntary movements and the cortex and the brainstem is necessary for normal swallowing.…”

“…Therefore, swallowing is divided into two components: voluntary and involuntary movement (Jean, 2001). Our iEEG study showed that HG activities in the cortex along the Sylvian fissure achieved the maximum values at the transition time from the voluntary to the involuntary phase (Hashimoto et al, 2021b). Moreover, swallowing is a unique movement since cooperation between motor output and sensory input is involved.…”

“…A total of eight participants were enrolled (Table 1), and the patient group in this study was the same as that used in our other published study (Hashimoto et al, 2020a(Hashimoto et al, , 2021b. All contacts showing HG power increase in eight participants were plotted on the left hemisphere of the Montreal Neurological Institute (MNI) normalized brain (Figure 3B).…”

“…The distribution pattern of the contacts observed in this study was concordant with that reported previously. In another study, we reported the distribution and dynamic changes of cortical oscillations, including HG activities, in detail (Hashimoto et al, 2021b).…”

“…Eight patients with intractable temporal lobe epilepsy participated in this study (four females, 15-51 years of age; mean and standard deviation (SD) of age 27.8 G 11.6 years) (Table 1), and the patient group in this study was the same group used in our other published study (Hashimoto et al, 2020a(Hashimoto et al, , 2021b…”