Functional connectivity of human chewing: an fcMRI study

Mastication is one of the most important orofacial functions. The neurobiological mechanisms of masticatory control have been investigated in animal models, but less so in humans. This project used functional connectivity magnetic resonance imaging (fcMRI) to assess the positive temporal correlations among activated brain areas during a gum-chewing task. Twenty-nine healthy young-adults underwent an fcMRI scanning protocol while they chewed gum. Seed-based fcMRI analyses were performed with the motor cortex and cerebellum as regions of interest. Both left and right motor cortices were reciprocally functionally connected and functionally connected with the post-central gyrus, cerebellum, cingulate cortex, and precuneus. The cerebellar seeds showed functional connections with the contralateral cerebellar hemispheres, bilateral sensorimotor cortices, left superior temporal gyrus, and left cingulate cortex. These results are the first to identify functional central networks engaged during mastication.

Brain activity and human unilateral chewing: an FMRI study

Brain mechanisms underlying mastication have been studied in non-human mammals but less so in humans. We used functional magnetic resonance imaging (fMRI) to evaluate brain activity in humans during gum chewing. Chewing was associated with activations in the cerebellum, motor cortex and caudate, cingulate, and brainstem. We also divided the 25-second chew-blocks into 5 segments of equal 5-second durations and evaluated activations within and between each of the 5 segments. This analysis revealed activation clusters unique to the initial segment, which may indicate brain regions involved with initiating chewing. Several clusters were uniquely activated during the last segment as well, which may represent brain regions involved with anticipatory or motor events associated with the end of the chew-block. In conclusion, this study provided evidence for specific brain areas associated with chewing in humans and demonstrated that brain activation patterns may dynamically change over the course of chewing sequences.

Use of mental health services by formerly homeless adults residing in group and independent housing

OBJECTIVE

The study examined patterns of mental health service use among 112 formerly homeless mentally ill adults to determine whether clients in a staffed group living situation would need fewer types of services or lesser amounts of some services than those living independently in single apartments.

METHODS

Clients in the Boston McKinney demonstration project were randomly assigned to two housing types: individual apartments or a group living situation designed to teach residents to manage the house and their own affairs with minimal staff presence. The types and amounts of services these clients used during an 18-month period were documented and compared.

RESULTS

Service use by all clients was heavy, especially use of inpatient psychiatric services. It did not differ by housing type. The large majority of clients in both housing types were able to remain housed and avoid homelessness. Clients who did not stay in assigned housing for the duration of the study had higher levels of inpatient service use, including detoxification and substance abuse treatment.

CONCLUSIONS

When homeless mentally ill adults are provided permanent housing and accessible mental health treatment and specialized social services, they are likely to avoid unstable housing patterns, which are associated with higher use of inpatient services.