Tactile motion lacks momentum.

The displacement of the final position of a moving object in the direction of the observed motion path, i.e. an overestimation, is known as representational momentum. It has been described both in the visual and the auditory domain, and is suggested to be modality-independent. Here, we tested whether a representational momentum can also be demonstrated in the somatosensory domain. While the cognitive literature on representational momentum suggests that it can, previous work on the psychophysics of tactile motion perception would rather predict an underestimation of the perceived endpoint of a tactile stimulus. Tactile motion stimuli were applied on the left and the right dorsal forearms of 32 healthy participants, who were asked to indicate the subjectively perceived endpoint of the stimulation. Velocity, length and direction of the trajectory were varied. Contrary to the prediction based on the representational momentum literature, participants in our experiment significantly displaced the endpoint against the direction of movement (underestimation). The results are thus compatible with previous psychophysical findings on the perception of tactile motion. Further studies combining paradigms from classical psychophysics and cognitive psychology will be needed to resolve the apparently paradoxical predictions by the two literatures.

Patient response to sleep apnea screening in a dental practice.

OBJECTIVE: This study investigated patient response to a recommendation for physician evaluation following screening for obstructive sleep apnea (OSA) in a dental practice. METHODS: In a community-based dental practice in Raleigh, North Carolina, 119 patients were recruited by nonprobability purposive sampling and administered both a validated subjective (STOP questionnaire) and objective (pulse oximeter) screening instrument for OSA. Patients who screened high-risk for OSA on either instrument were recommended to consult their physician within three months. All patients were contacted via telephone after three months to determine if they had consulted a physician regarding their screening results. Multivariate log-binomial models estimated prevalence ratios (PR) and 95 percent confidence limits (95% CL) for physician consultation according to OSA risk, adjusting for potential confounders. RESULTS: Overall, 18.5 percent of patients screened high-risk on the STOP questionnaire alone, 26.1 percent on pulse oximetry alone, and 31.9 percent on both instruments. Follow-up of 111 subjects (93.3%) found that 40 (47.1%) of those high-risk for OSA on one or both instruments sought physician evaluation. Patients who screened high-risk on pulse oximetry were 2.55 times as likely to seek physician evaluation compared with those who screened low-risk on both instruments (PR = 2.55, 95% CL: 1.02, 6.37). Screening high-risk on the STOP questionnaire did not significantly increase the likelihood of physician evaluation. CONCLUSIONS: Nearly, half of dental patients who screen high-risk for OSA may be responsive to a recommendation to seek physician evaluation.

Sleep medicine content in dental hygiene education.

According to the National Research Council, 70 million Americans chronically suffer from approximately 60 medically recognized sleep disorders. With most clinicians unaware of these disorders, many individuals remain undiagnosed. To effectively address this issue, health care professionals must work collaboratively to educate, identify, and treat patients with sleep disorders. However, medical and dental clinicians do not receive adequate education in sleep medicine. On the frontline regarding prevention and counseling, dental hygienists play an important role in patient education, screening, and management of sleep disorders. The aim of this study was to assess the amount of sleep medicine content in U.S. dental hygiene programs. An electronic survey was emailed to all 334 accredited U.S. dental hygiene programs. The 18-question survey assessed the sleep medicine content presented during the 2012-13 academic year. A total of 35.3% (n=118) of the programs responded. The mean number of hours devoted to sleep medicine in their curricula was 1.55 hours (SD=1.37). Although 69% (n=79) of the responding programs reported spending time on sleep bruxism (mean=1.38 hours, SD=0.85), only 28% (n=32) reported spending time on other topics such as snoring and obstructive sleep apnea (mean=1.39 hours, SD=0.72). These results suggest that sleep medicine is included in the majority of U.S. dental hygiene programs, but the content is limited and focused on sleep bruxism. This level of training is inadequate to prepare dental hygienists for their potential role in patient education, screening, and management of sleep-related breathing disorders.

Electromyographic evaluation of masticatory muscles in dentate patients versus conventional and implant-supported fixed and removable denture wearers- a preliminary report comparing model foods.

PURPOSE: To evaluate differences in masticatory muscle function during chewing of model foods designed to differ in fracture strength between dentate subjects (n = 5, ages 59 to 68 years) versus patients treated with a maxillary conventional complete denture opposing natural dentition or one of the following types of mandibular complete dentures: conventional, implant-supported overdenture, implant-supported fixed denture (n = 20, ages 45 to 83 years). The authors hypothesized that denture wearers would differ in duration of chewing, frequency of chewing, and masticatory muscle activity while preparing a bolus for swallowing. MATERIALS AND METHODS: Surface electromyography was recorded bilaterally from the masseter, anterior temporalis, and anterior digastric. Masticatory muscle activity was evaluated using scaled values of the area under the electromyographic curve, while subjects chewed agar-based model foods with different fracture strengths. Chewing duration and frequency also were calculated from electromyographic recordings. Mixed model analysis of variance with "subject" as a random factor was used during statistical analysis. Logarithmic transformation was required to achieve normalization of residuals for the duration of chewing and the relative masticatory muscles activity, but not for the chewing frequency. RESULTS: Relative masticatory muscle activity was 2.57 times higher for the denture wearers than for the dentate subjects during chewing of model foods (P < .0001). The reduction in masticatory muscle activity from the 1st to the 10th chewing cycle was proportionally less in magnitude and occurred more gradually for denture wearers compared to dentate subjects. While chewing sequence duration increased with food fracture strength, it did not differ significantly in treatment versus dentate groups. Chewing cycle frequency did not differ between groups or with food fracture strength. CONCLUSIONS: The observed increases in relative masticatory muscle activity for denture wearers compared to the dentate subjects during oral food processing likely reflect supplemental mechanical efforts to accommodate the use of dentures for preparing a bolus for swallowing.

Nonverbal patient with autism spectrum disorder and obstructive sleep apnea: use of desensitization to acclimatize to a dental appliance.

Patients with autism spectrum disorders (ASDs) may have difficulty tolerating conventional dental treatment due to aberrant sensory responsiveness. The purpose of this report was to describe the successful treatment of obstructive sleep apnea (OSA) in a nonverbal 20-year-old male patient with ASD using a dental appliance. A series of appointments prepared the patient for the required treatment procedures and desensitized him for use of the final appliance. The final appliance improved outcomes of a post-treatment sleep study, indicating successful treatment of OSA. Understanding the specific challenges of patients with ASD and the patience and foresight of providers in approaching these challenges, in collaboration with caregivers, can contribute to improved health outcomes for these patients.

Perceptual and neural response to affective tactile texture stimulation in adults with autism spectrum disorders.

Autism spectrum disorders (ASD) are associated with differences in sensory sensitivity and affective response to sensory stimuli, the neural basis of which is still largely unknown. We used psychophysics and functional magnetic resonance imaging (fMRI) to investigate responses to somatosensory stimulation with three textured surfaces that spanned a range of roughness and pleasantness in a sample of adults with ASD and a control group. While psychophysical ratings of roughness and pleasantness were largely similar across the two groups, the ASD group gave pleasant and unpleasant textures more extreme average ratings than did controls. In addition, their ratings for a neutral texture were more variable than controls, indicating they are less consistent in evaluating a stimulus that is affectively ambiguous. Changes in brain blood oxygenation level-dependent (BOLD) signal in response to stimulation with these textures differed substantially between the groups, with the ASD group exhibiting diminished responses compared to the control group, particularly for pleasant and neutral textures. For the most unpleasant texture, the ASD group exhibited greater BOLD response than controls in affective somatosensory processing areas such as the posterior cingulate cortex and the insula. The amplitude of response in the insula in response to the unpleasant texture was positively correlated with social impairment as measured by the Autism Diagnostic Interview-Revised (ADI-R). These results suggest that people with ASD tend to show diminished response to pleasant and neutral stimuli, and exaggerated limbic responses to unpleasant stimuli, which may contribute to diminished social reward associated with touch, perpetuating social withdrawal, and aberrant social development.

Temporomandibular disorder modifies cortical response to tactile stimulation.

UNLABELLED: Individuals with temporomandibular disorder (TMD) suffer from persistent facial pain and exhibit abnormal sensitivity to tactile stimulation. To better understand the pathophysiological mechanisms underlying TMD, we investigated cortical correlates of this abnormal sensitivity to touch. Using functional magnetic resonance imaging (fMRI), we recorded cortical responses evoked by low-frequency vibration of the index finger in subjects with TMD and in healthy controls (HC). Distinct subregions of contralateral primary somatosensory cortex (SI), secondary somatosensory cortex (SII), and insular cortex responded maximally for each group. Although the stimulus was inaudible, primary auditory cortex was activated in TMDs. TMDs also showed greater activation bilaterally in anterior cingulate cortex and contralaterally in the amygdala. Differences between TMDs and HCs in responses evoked by innocuous vibrotactile stimulation within SI, SII, and the insula paralleled previously reported differences in responses evoked by noxious and innocuous stimulation, respectively, in healthy individuals. This unexpected result may reflect a disruption of the normal balance between central resources dedicated to processing innocuous and noxious input, manifesting itself as increased readiness of the pain matrix for activation by even innocuous input. Activation of the amygdala in our TMD group could reflect the establishment of aversive associations with tactile stimulation due to the persistence of pain. PERSPECTIVE: This article presents evidence that central processing of innocuous tactile stimulation is abnormal in TMD. Understanding the complexity of sensory disruption in chronic pain could lead to improved methods for assessing cerebral cortical function in these patients.

Tactile perception in adults with autism: a multidimensional psychophysical study.

Although sensory problems, including unusual tactile sensitivity, are heavily associated with autism, there is a dearth of rigorous psychophysical research. We compared tactile sensation in adults with autism to controls on the palm and forearm, the latter innervated by low-threshold unmyelinated afferents subserving a social/affiliative submodality of somatosensation. At both sites, the groups displayed similar thresholds for detecting light touch and innocuous sensations of warmth and cool, and provided similar hedonic ratings of the pleasantness of textures. In contrast, increased sensitivity to vibration was seen in the autism group on the forearm, along with increased sensitivity to thermal pain at both sites. These findings suggest normal perception along with certain areas of enhanced perception in autism, consistent with previous studies.