Peak Morphology and Scalp Topography of the Pharyngeal Sensory-Evoked Potential

Abstract

The initiation of the pharyngeal stage of swallowing is dependent upon sensory input to the brainstem and cortex. The event-related evoked potential provides a measure of neuronal electrical activity as it relates to a specific stimulus. Air-puff stimulation to the posterior pharyngeal wall produces a sensory evoked potential (PSEP) waveform. The goal of this study was to characterize the scalp topography and morphology for the component peaks of the PSEP waveform. Twenty-five healthy men and women served as research participants. PSEPs were measured via 32 electrode cap (10-20 system) connected to SynAmps2 Neuroscan EEG System. Air puffs were delivered directly to the oropharynx using a thin polyethylene tube connected to a flexible laryngoscope. The PSEP waveform is characterized by 4 early and mid-latency components peaks: an early positivity (P1), and negativity (N1), followed by a mid-latency positivity (P2), and negativity (N2). The early positive peak P1 is localized bilaterally to the lateral parietal scalp, the N1 medially in the fronto-parietal region, and the P2 and N2 with diffuse scalp locations. Somatosensory and premotor regions are possible anatomical correlates of peak locations. Based on the latencies of the peaks, they are likely analogous to somatosensory and respiratory related evoked potential peaks.

Alterations in oropharyngeal sensory evoked potentials (PSEP) with Parkinson’s disease

“…The aim of this study was to examine the effect of PD on pharyngeal somato-sensation using the PSEP protocol (Wheeler-Hegland et al, 2010, 2011). P1, N1, P2 component peaks were identified in all study participants, while N2 peaks were present in 85% (17/20) of the total participants.…”

“…The oropharyngeal air-puff elicited various sensations including urge to swallow, cough and gag. In fact, Wheeler-Hegland, et al (2011) examined urge-to-cough, in response to the same pharyngeal air-puff stimulation in young adults, and found that 68% of air-puff trials elicited an urge-to-cough response. Thus, due to the placement of the scope and the sensations reported, it is unlikely that the participants were able to ignore the stimulus throughout the experiment.…”

“…The PSEP protocol was conducted according to the technique of Wheeler-Hegland and colleagues (Wheeler-Hegland et al, 2010, 2011). Participants were seated comfortably with the back, neck and head supported.…”

“…A mouthpiece with a polyethylene tube was placed in the mouth, and a flexible laryngoscope was inserted through the tube (identical to Wheeler-Hegland et al (2011) Figure 1). The laryngoscope images were displayed, but not recorded, on a computer screen.…”

“…The cerebral cortex is thought to be important in sensory processing, attention, and the affective process of the stimulus (Ashraf et al, 2008; Babiloni et al, 1999; Chan and Davenport, 2008; Colon et al, 1983; Crowley and Colrain, 2004; Davenport et al, 2007; Davenport et al, 1996; Davenport et al, 2000; Davenport et al, 1986; Desmedt et al, 1983; Folstein and Van Petten, 2008; von Leupoldt et al, 2013). To evaluate this sensory system, an air-puff was applied to the oropharyngeal wall and cortical sensory evoked potentials (EP) were recorded from the scalp using electroencephalography (EEG) (Wheeler-Hegland et al, 2010, 2011). Wheeler-Hegland, et.…”