A role of anterior cingulate cortex in the emergence of worker-parasite relationship.

We studied the brain mechanisms underlying action selection in a social dilemma setting in which individuals' effortful gains are unfairly distributed among group members. A stable "worker-parasite" relationship developed when three individually operant-conditioned rats were placed together in a Skinner box equipped with response lever and food dispenser on opposite sides. Specifically, one rat, the "worker," engaged in lever-pressing while the other two "parasitic" rats profited from the worker's effort by crowding the feeder in anticipation of food. Anatomically, c-Fos expression in the anterior cingulate cortex (ACC) was significantly higher in worker rats than in parasite rats. Functionally, ACC inactivation suppressed the worker's lever-press behavior drastically under social, but only mildly under individual, settings. Transcriptionally, GABAA receptor- and potassium channel-related messenger RNA expressions were reliably lower in the worker's, relative to parasite's, ACC. These findings indicate the requirement of ACC activation for the expression of exploitable, effortful behavior, which could be mediated by molecular pathways involving GABAA receptor/potassium channel proteins.

Evaluation of salivary aspiration in brain-injured patients with tracheostomy.

OBJECTIVE: To determine the useful tool for evaluating salivary aspiration in brain-injured patients with tracheostomy. METHODS: Radionuclide salivagram and laryngoscopy was done in 27 brain-injured patients with tracheostomy. During salivagram, (99m)Tc sulfur colloid was placed sublingually in the supine position, and 50-minute dynamic images and 2-hour delayed images were obtained. Salivary aspiration was detected when the tracer was entered into the major airways or lung parenchyma. Laryngoscopy was done by otolaryngologists, and saliva aspiration, saliva pooling, and vocal cord palsy were evaluated. Videofluoroscopic swallowing study was done in patients who were able to undergo the test. RESULTS: The detection rate of salivary aspiration was 44.4% with salivagram, and 29.6% with laryngoscopy. The correlation of the two tests was 70.4%. Of the laryngoscopy findings, salivary pooling had significant correlation with positive salivagram results (p=0.04). Frequent need of suction correlated with salivary aspiration in both salivagram (p=0.01) and laryngoscopy (p=0.01). Patients with negative results in salivagram or laryngoscopy had higher rates of progressing to oral feeding or tapering tracheostomy. Two patients developed aspiration pneumonia, and both patients only showed aspiration in salivagram. CONCLUSION: Brain-injured patients with tracheostomy have a high risk of salivary aspiration. Evaluation of salivary aspiration is important, as it may predict aspiration pneumonia and aids in clinical decisions of oral feeding or tracheostomy removal. Salivagram is more sensitive than laryngoscopy, but laryngoscopy may be useful for evaluating structural abnormalities or for follow-up examinations to assess the changes.

Measurements of anteroposterior and intersidal asymmetry in patients with diabetic peripheral neuropathy.

OBJECTIVE: The aim of this study was to investigate the anteroposterior and intersidal asymmetric weight bearing and plantar pressure in patients with mild diabetic peripheral neuropathy. DESIGN: A total of 102 subjects were enrolled in this study. Plantar pressure and anteroposterior and intersidal weight-bearing patterns on a foot plate were measured using Gaitview while standing and during dynamic walking. The subjects were evaluated with nerve conduction study, vibration sensory threshold (VST), and Diabetic Neuropathy Symptom (DNS) scores. RESULTS: The subjects were classified into normal nerve conduction study and mild diabetic peripheral neuropathy groups according to the results of the nerve conduction study tests. The two groups differed significantly in asymmetric weight-bearing pattern, DNS score, and VST. The sensitivities of anteroposterior and intersidal asymmetry were similar to those of DNS score and VST, with significant correlations between asymmetric weight bearing and VST and DNS scores. In contrast, highest plantar pressure did not differ significantly in the two groups and was not significantly correlated with nerve conduction study, VST, or DNS score. CONCLUSIONS: Measurements of asymmetric weight bearing may indicate the clinical significance of mild diabetic peripheral neuropathy similar as other screening tools. Asymmetric weight-bearing pattern may be useful for evaluating patients in the early period of diabetes mellitus because proper management would prevent further complications and improve quality-of-life.

Pressure monitoring of multilayer inelastic bandaging and the effect of padding in breast cancer-related lymphedema patients.

OBJECTIVE: This study of pressure monitoring of multilayer inelastic bandaging and the effect of padding in breast cancer-related lymphedema patients aimed to measure the resting and working sub-bandage pressures in compression therapy for lymphedema patients and to determine whether applying additional padding has an additional effect in volume reduction of the limb. DESIGN: Forty-eight patients with breast cancer who were beginning complex decongestive therapy for lymphedema were included. In 24 patients, padding was added to the forearm. A short-stretch bandage with or without padding was applied to the affected arm. The working pressure was measured while the patients squeezed a rubber device. The forearm limb circumference was measured before and after 2 wks of treatment. RESULTS: The mean (SD) of the resting pressure was 36.3 (2.2) mm Hg without padding and 49.5 (3.2) mm Hg with padding. The mean (SD) of the working pressure was 9.5 (3.7) mm Hg without padding and 24.3 (9.1) mm Hg with padding (P < 0.05). The volume loss after treatment was significantly greater in the group with added padding (P < 0.05). CONCLUSIONS: The working pressure during exercising with a force of 50 Pa is approximately 10 mm Hg with a short-stretch bandage applied. Adding a pad increases both the resting and the working pressure and also seems to be effective in increasing volume reduction of the limb.