Functional brain network mechanism of executive control dysfunction in temporal lobe epilepsy.

BACKGROUND: Executive control dysfunction is observed in a sizable number of patients with temporal lobe epilepsy (TLE). Neural oscillations in the theta band are increasingly recognized as having a crucial role in executive control network. The purpose of this study was to investigate the alterations in the theta band in executive control network and explore the functional brain network mechanisms of executive control dysfunction in TLE patients. METHODS: A total of 20 TLE patients and 20 matched healthy controls (HCs) were recruited in the present study. All participants were trained to perform the executive control task by attention network test while the scalp electroencephalogram (EEG) data were recorded. The resting state signals were collected from the EEG in the subjects with quiet and closed eyes conditions. Functional connectivity among EEGs in the executive control network and resting state network were respectively calculated. RESULTS: We found the significant executive control impairment in the TLE group. Compared to the HCs, the TLE group showed significantly weaker functional connectivity among EEGs in the executive control network. Moreover, in the TLE group, we found that the functional connectivity was significantly positively correlated with accuracy and negatively correlated with EC_effect. In addition, the functional connectivity of the executive control network was significantly higher than that of the resting state network in the HCs. In the TLE group, however, there was no significant change in functional connectivity strengths between the executive control network and resting state network. CONCLUSION: Our results indicate that the decreased functional connectivity in theta band may provide a potential mechanism for executive control deficits in TLE patients.

Mood Disorders are Correlated with Autonomic Nervous Function in Chronic Insomnia Patients with OSA.

Purpose: To evaluate the correlation between sleep microstructure, autonomic nervous system activity, and neuropsychological characteristics in chronic insomnia (CI) patients with obstructive sleep apnea (OSA). Patients and Methods: Forty-five CI-OSA patients, forty-six CI patients and twenty-two matched healthy control subjects (HCs) were enrolled. CI-OSA patients were then divided into two groups: mild OSA and moderate-to-severe OSA. All participants completed neuropsychological tests, which included the Hamilton Depression and Anxiety Scales (HAMD and HAMA), the Pittsburgh Sleep Quality Index (PSQI), the Insomnia Severity Index (ISI), the Epworth Sleepiness Scale (ESS), and the Mini-mental State Examination (MMSE). The autonomic nervous system activity and sleep microstructure were examined by the PSM-100A. Results: The CI-OSA patients exhibited higher scores on the PSQI, ESS, ISI, HAMA, and HAMD than HCs and CI patients (all p < 0.01). The CI-OSA patients had a lower proportion of stable sleep, REM sleep and a higher proportion of unstable sleep ratio (all p < 0.01) than HCs and CI patients (all p < 0.01). The CI-OSA patients had higher ratios of LF and LF/HF, and lower ratios of HF and Pnn50% (all p < 0.01) than HCs and CI patients (all p < 0.01). Compared to CI-mild OSA patients, the CI-moderate-to-severe OSA patients presented with a higher ESS scores, higher ratios of LF and LF/HF, and lower ratios of HF (all p < 0.05). In CI-OSA patients, higher HAMD scores were correlated with decreased MMSE scores (r=-0.678, p < 0.01). A higher LF ratio was correlated with higher HAMD and HAMA scores (r=0.321, p=0.031, r =0.449, p =0.002), and a higher HF ratio was correlated with lower HAMD and HAMA scores (r=-0.321, P =0.031, r =-0.449, p =0.002). Conclusion: OSA exacerbates the abnormalities of sleep microstructure and the autonomic nervous dysfunction in CI patients. Dysfunction of the autonomic nervous system could contribute to mood deterioration in CI with OSA patients.

Theta oscillation and functional connectivity alterations related to executive control in temporal lobe epilepsy with comorbid depression.

OBJECTIVE: Depression is widely acknowledged as the most common comorbidity of temporal lobe epilepsy (TLE), and executive control (EC) may be particularly impaired in patients with TLE with comorbid depression. The purpose of this study was to investigate brain network alterations in patients with TLE with or without depression using scalp electroencephalography (EEG), and to explore the potential mechanisms of TLE with comorbid depression. METHODS: Forty patients with TLE and 20 healthy controls (HC) were recruited for administered the BDI-II and HAMD-17 surveys. The patients with TLE were divided into those with depression (PDS, n = 20) and those without depression (nPDS, n = 20) according to the surveys. Neural oscillations and functional connectivity during performance of EC tasks were calculated during EEG. RESULTS: Theta oscillation and functional connectivity were significantly weakened in the PDS group compared to the nPDS and HC groups. Furthermore, the PDS group showed more serious EC dysfunction than nPDS group. CONCLUSIONS: Our results indicated that weakened theta oscillation and functional connectivity in the frontal lobe may be a mechanism of EC dysfunction in TLE with comorbid depression. SIGNIFICANCE: The present results suggest that the alterations in frontal lobe connections may help predict the depression in patients with TLE.