Browsing by Subject "stress"

Faculty: Faculty of Biological and Environmental Sciences Degree programme: Master’s Programme in Neuroscience Study track: Neuroscience Author: Emma-Helka Erkkilä Title: The brain physiology of stress and the effects of burnout on executive functions Level: Master’s thesis Month and year: 08/2022 Number of pages: 35 Keywords: executive functions, emotion, cognition, stress, burnout Supervisor or supervisors: Docent Kaisa Hartikainen and Lic.Med. Mia Pihlaja Where deposited: Helsinki University Library Additional information: Abstract: BACKGROUND- Burnout as a result of prolonged and excessive stress may impair higher order cognitive functions of the brain such as executive functions and their efficiency. This Master's thesis examines the effects of chronic stress on the brain, more specifically the effects of burnout on executive functions. The aim of this study was to specifically research the effects of burnout on executive and emotional functions and their interaction. The research was conducted at the Behavioral Neurology Research Unit, Tampere University Hospital as part of Sustainable Brain Health project funded by the European Social Fund. MATERIAL AND METHODS- 54 voluntary examinees of whom 51 were analyzed. The examinees were divided into two groups based on BBI-15 survey (27 suffering from burnout and 24 control subjects without burnout). The examinees performed a computer-based Executive reaction time (RT) test, during which a 64-channel electroencephalogram (EEG) was recorded. In additions all examinees received alternating transcutaneous vagus nerve stimulation (tVNS) and placebo stimulation. From the Executive RT test, we obtained objective measures reflecting the efficiency of executive functions (RT and total errors) and specific executive functions such as working memory, inhibition and attention. Additionally, the emotional stimulus included in the test enabled the assessment of the emotional functions and the interaction between emotional and executive functions. The EEG and tVNS results were not in the scope of this master’s thesis, and they will be reported later on. RESULTS- The results of this thesis are preliminary. Distinct positive correlation was observed between burnout assessment based on the BBI-15 survey and the results of the BRIEF-A self-report which measures the subjective experience of challenges in executive functions in daily life. There was no statistically significant (p<0.05) difference between the groups in RTs or errors made in the Executive function RT test. Instead, the groups differed on how the threatening emotional stimulus affected the accuracy of responses. Subjects suffering from burnout made less errors with a threatening emotional stimulus compared to a neutral stimulus and vice versa the control subjects made more errors with the threatening emotional stimulus compared to neutral. This difference was statistically significant (p=0,025). DISCUSSION- Challenges experienced in everyday executive functions were linked with burnout. However, RTs and errors in the Executive reaction time test did not correlate with the severity of the burnout nor were the self-evaluated problems in executive functions depicted in the test performance. Instead, the subjects suffering from burnout differed from the control group in how the threatening stimulus affected the accuracy of responses in the test. It is possible that the subjects suffering from burnout benefit from the increase in arousal caused by the threatening emotional stimulus which was shown as improved accuracy of responses when there was a threatening stimulus, whereas the control group's accuracy of responses was disrupted by the threatening stimulus. We speculate that if the control group’s baseline level of arousal was optimal then the threatening emotional stimulus may have increased arousal to suboptimal level causing decrease in performance. Subjectively experienced challenges in executive functions and objective changes in the interaction between emotions and the executive functions were observed in the study. In conclusion, burnout causes changes in executive functions.

Domesticated horses have been used for various tasks over their thousands of years of shared history with humans. To be able to perform these tasks every horse needs to learn the needed skills, and this requires systematic training. Training of adult horses has been studied for a long time and comparisons between the efficacy of different training methods have been done. There have also been some studies comparing how much and when young foals need to be handled for them to grow into easily trainable adults. From adult horses it is known that emotional state affects cognitive processes and with that also their learning efficiency and speed. The early stages of training young horses have not been studied very well. There is no clear picture about how young horses feel during training and how that affects their learning. In my thesis I studied young horses’ emotional states while learning new tasks and how that affects their learning. I followed the early training of 19 young horses (11 one-year-olds and 8 two- and three-year-olds) by videotaping five training sessions and collecting saliva samples before and after three of those sessions to analyse cortisol and oxytocin. From the videos I analysed how fast horses responded to trainer’s asks and how unfocused they were. From the hormone samples I measure the change in cortisol and oxytocin levels during training. Salivary cortisol has been widely used to measure acute stress. Oxytocin on the other hand is a newer indicator for positive emotions. To the best of my knowledge salivary oxytocin has never been used in horses. My data showed that the horses learned the required tasks: they became quicker at their responses and focused better during the course of training. Because my data was quite small and individual variation in the hormone levels was high, the results might have been affected by these factors. Linear mixed effect models showed that higher oxytocin levels before training session predicted quicker responses during training and lower levels after training predicted lower focusedness. Bigger increase in cortisol levels during training compared to the before level explained quicker responses and better focusedness, but higher levels before training resulted to lower focusedness and slower responses. This is in line with previous studies of adult horses, that showed that horses in a better emotional state and with less stress learn faster and are more interested in working with humans. This shows that it is important to not only focus on physical wellbeing but also mental wellbeing from early on in horses’ life.