University of Twente Student Theses


Infra-slow Electroencephalographic Activity during Stress

Brinkman, S.L. (2018) Infra-slow Electroencephalographic Activity during Stress.

[img] PDF
Abstract:OBJECTIVE: In approximately half of all epilepsy patients stress is the most frequently reported factor precipitating seizures. Additionally, in electroencephalography (EEG) studies, infra-slow oscillations, oscillations with frequencies below 0.1 Hz, have been proven to be enhanced during stress and during seizures, with different types of seizures possessing specific infra-slow spatiotemporal signatures. Because of this, it is very likely that stress and infra-slow activity (ISA) are related. The main goal of this study is to investigate the influence of stress on infra-slow EEG activity. METHODS: The study consisted of a randomised crossover pilot study on healthy adults. For this study, subjects underwent EEG monitoring twice. During each monitoring a stressor was induced. The Cold-Pressor Test (CPT) and physical exercise performed on a treadmill (PET) served as two different stressors. EEGs were recorded for half an hour before and after stressor induction. In this way each measurement included a control at rest. Stress was determined using salivary cortisol levels. For this, saliva samples were collected before and after both tests. EEGs were filtered between 0.01 and 0.1 Hz to obtain the (ISA). Quantitative EEG measures, consisting of the ISA power, mean ISA amplitude, mean ISA frequency and the Modulation Index (MI) were calculated before and after both tests. These measures were also calculated for a separate lead placed on the non-dominant arm to investigate ISA not originating from the brain. RESULTS: ISA was present in all signals. Significant EEG results (p<0.05) consisted of: An increased salivary cortisol concentration after both tests. After the CPT the concentration increased from 9.75 (3.5) to 10.8 (3.8) nmol/L. After the PET the concentration increased from 8.5 (8.6) to 10.6 (8.6) nmol/L. A total increase in power in the ISA frequency band after both tests, from 1.48e7 (2.37e7) to 2.06e7 (3.14e7) μV2/Hz after the CPT, and from 9.62e6 (5.96e6) to 1.93e7 (6.88e6) μV2/Hz after the PET An increased mean infra-slow frequency after the CPT, with a value of 0.031 (0.002) Hz before, and a value of 0.033 (0.003) Hz after the test. The mean infra-slow amplitude increased after the PET, with values of 21.82 (7.6) before, and 28.87 (12.5) μV after the PET. Significant ISA changes were also found in the arm lead. The total power increased from 7.83e7 (1.86e8) to 1.49e8 (2.89e8) μV2/Hz after the CPT. In addition to this, the mean amplitude decreased from 51.52 (23.72) to 38.41 (18.37) μV after the CPT. The MI increased after the CPT from 8.5e-4 (4.9e-4) to 2.3e-3 (2.8e-3). After the PET, the mean frequency increased, from 0.023 (0.004) to 0.028 (0.007) Hz, after the PET. CONCLUSIONS: Significant changes were found in the infra-slow characteristics after stress. Because the ISA of the EEG and the arm-lead changed after the stressors, infra-slow activity could prove useful for monitoring and diagnostic purposes
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine
Programme:Technical Medicine MSc (60033)
Link to this item:
Export this item as:BibTeX
HTML Citation
Reference Manager


Repository Staff Only: item control page