Brow and Masticatory Muscle Activity Senses Subjective Hedonic Experiences during Food Consumption

Sensing subjective hedonic or emotional experiences during eating using physiological activity is practically and theoretically important. A recent psychophysiological study has reported that facial electromyography (EMG) measured from the corrugator supercilii muscles was negatively associated with hedonic ratings, including liking, wanting, and valence, during the consumption of solid foods. However, the study protocol prevented participants from natural mastication (crushing of food between the teeth) during physiological data acquisition, which could hide associations between hedonic experiences and masticatory muscle activity during natural eating. We investigated this issue by assessing participants’ subjective ratings (liking, wanting, valence, and arousal) and recording physiological measures, including EMG of the corrugator supercilii, zygomatic major, masseter, and suprahyoid muscles while they consumed gel-type solid foods (water-based gellan gum jellies) of diverse flavors. Ratings of liking, wanting, and valence were negatively correlated with corrugator supercilii EMG and positively correlated with masseter and suprahyoid EMG. These findings imply that subjective hedonic experiences during food consumption can be sensed using EMG signals from the brow and masticatory muscles.

The Relationship between Stress and Masticatory Muscle Activity in Female Students

The aim of the study was to analyze the relationship between stress measured by the perceived stress scale (PSS-10) questionnaire and masticatory muscle activity. Experimental design assumed the study of healthy young women without temporomandibular disorders, dividing them into three groups depending on the result of the stress level and then comparing these groups in terms of bioelectrical activity of the masticatory muscles. After the exclusion criteria were applied, 63 female students (mean age: 22.3 ± 2.4 years) from Medical University of Lublin were included in the study. The subjects were then divided into 3 groups: with low (n = 18), medium (n = 18) and high stress level (n = 27), according to PSS-10 results. Resting and functional activity of temporalis anterior (TA) and masseter (MM) muscles were measured by electromyograph BioEMG III. There were statistically significant effects of group on the absolute value of asymmetry index (AsI) of TA and MM during maximum voluntary clenching on dental cotton rollers (both p = 0.02). Post hoc analysis shows that there were statistically significant differences between medium and high stress groups in AsI TA (p = 0.01) and between low and high stress groups in AsI MM (p = 0.02). Perceived stress measured by PSS-10 questionnaire seems to be associated with changes in muscular asymmetry in functional clenching activity.

Relationships between cortical, cardiac, and arousal-motor activities in the genesis of rhythmic masticatory muscle activity across sleep cycles in primary sleep bruxism children

Study Objectives The present study aimed to clarify the physiological relationships between rhythmic masticatory muscle activity (RMMA) and cyclic changes in cortical, autonomic, and arousal-motor activities during sleep in sleep bruxism (SB) children. Methods Polysomnographic recordings were performed on fifteen SB children (9 boys, 6 girls, 10.3 ± 2.5 years) and eighteen control children (5 boys, 13 girls, 10.7 ± 3.1 years) free from sleep and developmental disorders. Sleep and RMMA were scored by the standard rules. Sleep cycle was divided into NREM and REM sleep segments and the frequency of RMMA, transient arousal and movement, and cortical and cardiac activities were then quantitatively analyzed in relation to sleep cycles. Results Neither sleep architecture nor sleep stage distribution of RMMA significantly differed between two groups. In sleep cycles, SB children showed more frequent RMMA in all segments than controls, while cyclic changes in cortical and autonomic activities did not significantly differ between two groups. In SB children, RMMA was the most frequent in the last NREM segment before REM sleep and was associated with increases in cortical beta activity and arousal; more than 70% of RMMA time-dependently occurred with cortical and motor arousals. Conclusions This is the first study to suggest that the potentiation of RMMA occurrence was associated with transient arousal under cyclic sleep processes in primary SB children.

Novel Functional Indices of Masticatory Muscle Activity

The aim of the present study was to analyze novel functional indices of masticatory muscle activity and compare them to existing and commonly used indices in patients with temporomandibular disorders (TMDs) and healthy adults. Based on the Research Diagnostic Criteria for Temporomandibular Disorders, 78 adult women qualified for the study. Subjects were divided into two groups: diagnosed TMDs (n = 36; mean age: 23.4 ± 2.6 years) and healthy adults (n = 42; mean age: 22.4 ± 2.3 years). Measurements of the bioelectric activity of the temporalis anterior (TA), superficial masseter (MM), and anterior bellies of the digastric muscle (DA) were carried out using the BioEMG III ™. Functional Clenching (FCI) and Functional Opening (FOI) indices were obtained as the ratio of the difference between the mean muscle root mean square (RMS) potentials during functional activity, including clenching (CL) and opening (MMO), and mean muscle resting (REST) potentials. Next, based on FCI and FOI indices, the Functional Clenching Activity Index (FCAI), Functional Clenching Symmetry Index (FCSI), and Functional Opening Symmetry Index (FOSI) were obtained. The statistical analysis showed significant differences in activity index left-sided (AcIL) and Activity index both-sided (AcItot) between TMDs and healthy women during rest measurements. The significant differences between both groups were noted in terms of all Functional Clenching Indices except Functional Clenching Index for MM right-sided (FCIMM-R). In all analyzed FCI indices, the control group showed higher values compared to the TMDs. Moreover, a significant difference between TMDs and controls was observed within Functional Clenching Activity Index left-sided (FCAIL) (14.56 vs. −0.45, p = 0.01). Both functional indices, and asymmetry (AsI) and activity (AcI) indices seem to be reliable in assessing symmetry and activity within masticatory muscles. Further studies should be performed to verify the effectiveness and suitability of the assessment of masticatory muscles using functional indices.