Non-Painful Tactile Stimuli and Sleep

Abstract

Introduction The aim of this study is to examine electrophysiological responses in the brain to painless somatosensory stimulation during sleep. Materials and Methods Fifteen healthy volunteers (8 female, with mean age: 22.13±1.41) participated in the study. Recordings were carried out using NuAmps 40 channeled recording system, pneumatic stimulation unit (Somatosensory Stimulus Generator 4-D Neuroimaging), Embedded Microcontroller Stimulation Unit (EMISU), and additional equipment such as video recording system and analysis computer. Painless air pressure stimulation was applied at constant pressure rate to the fore and middle fingers of the right hand. Infrequent oddball stimulation was applied to one of the fingers (%25 of the time). Continuous electroencephalography (EEG), electrooculography (EOG) and electromyography (EMG) recordings were sorted into sleep phases according to the guidelines set by the American Academy of Sleep Medicine (AASM). Responses recorded from the C3 and C4 electrodes were examined as somatosensory regions of priority. Paired samples T-tests were used for statistical analysis. Results N100, P200, N300, P450, N550, P900 Nlate wave forms were clearly observed for both frequent and infrequent stimuli in light and deep sleep. Responses to both target and non-target stimuli on the right hand were found to be similar to each other. Discussion Brain responsiveness continues in sleep; however electrophysiological response pattern can vary. Furthermore as processes such as directed attention, stimulus discrimination and working memory cannot be voluntarily employed during sleep; responses to both kinds of stimuli are similar to one another.

Keywords

• Sleep
• electroencephalography
• somatosensory event related potential
• electrophysiology