The Association between Symptoms of Autonomic Neuropathy and the Heart Rate Variability in Diabetics.

BACKGROUND: There are few tools to detect the diabetic autonomic neuropathy at an earlier stage. This study was conducted to investigate the association between symptoms of autonomic neuropathy and the heart rate variability (HRV) in diabetics. METHODS: Study subjects consisted of 50 diabetic patients and 30 outpatient hospital control patients at a university family medicine department. The patients completed a Korean version of composite autonomic symptom scale (COMPASS). Electrocardiography was recorded in the supine position, on standing, and during deep breathing, for 5 minutes each. HRV of frequency domain was calculated by power spectral analysis. RESULTS: The COMPASS score was higher in female diabetic patients compared with that in controls. Among 50 diabetic patients, the total COMPASS score correlated positively with normalized low frequency (LF) score (normalized units, n.u.) (r = 0.62, P < 0 .001) and low frequency/high frequency (LF/HF) (r = 0.77, P < 0.001), negatively with normalized HF score (n.u.) (r = -0.59, P < 0.001) and RMSSD (square root of the mean of the sum of the square of differences between adjacent NN interval; r = -0.33, P = 0.031). The decrease in LF (n.u) and the increase in HF (n.u) by deep breathing from the supine position were higher in diabetic patients compared with those in controls. The increase in LF (n.u) and the decrease in HF (n.u) by standing from the supine position were lower in diabetic patients compared with those in controls. CONCLUSION: The COMPASS score correlated with some component score of the HRV in diabetics. The HRV may be used as a tool to detect diabetic autonomic neuropathy by augmentation with position change.

Ecologically relevant stressors modify long-term memory formation in a model system.

Stress can alter adaptive behaviours, and as well either enhance or diminish learning, memory formation and/or memory recall. We focus attention on how environmentally relevant stressors (e.g. predator detection, crowding, and low concentrations of environmental Ca(++)) alter memory formation in the pond snail, Lymnaea stagnalis. We specifically look at operant conditioning of aerial respiration and whether or not long-term memory forms following the acquisition of the learned event, not performing aerial respiration. We will also examine the strain differences in Lymnaea which allow or cause isolated populations to possess different heritable cognitive capabilities, as manifested by differing abilities to form long-term memory.