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Behavioural changes after repeated social stress: exploring the neurophysiological mechanisms that determine susceptibility to stress

Boesjes, Rutger (2018) Behavioural changes after repeated social stress: exploring the neurophysiological mechanisms that determine susceptibility to stress. Bachelor's Thesis, Biology.


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The behavioural and physiological responses of long-lasting exposure to social stress differ between individual animals. While some animals avoid social interaction after chronic social stress, others appear unaffected. Social avoidance after chronic stress tends to be interpreted as a pathological, depressive-like state. However, this assumption is challenged by the idea that social avoidance after chronic defeat is an adaptive style of coping with stress, rather than a maladaptive response. Different stress coping styles are known to be determined by individual variation in the activation of a basic, well-conserved corticolimbic circuit. One of the subregions in this circuit is the mesolimbic pathway, which consist of the ventral tegmental area (VTA) and its projections to the nucleus accumbens (NAc). This pathway is associated with the attribution of salience to emotional stimuli, and appears to be activated after social interactions. Additionally, activity of the mesolimbic system is known to play a regulatory role in the behavioural response to stress. Although the neuroanatomical features of the mesolimbic area and its projections to other limbic and cortical regions are well-described, it remains challenging to understand how the properties of individual neurons within this pathway ultimately regulate differences in coping styles. This paper is aimed at explaining the mechanisms that underlie different responses of mesolimbic neurons to social stressors. I will argue that social avoidance of stress-susceptible individuals after chronic social defeat is the consequence of increased excitability of VTA neurons, while animals that are unsusceptible to social stress show no changes in neuronal excitability. Increased excitability has profound influences on transcriptional activity, neuronal plasticity and ultimately the allocation of memory in newly formed neural circuits. Additionally, the initial differences in neuronal excitability in the VTA could be the consequence of epigenetic regulation.

Item Type: Thesis (Bachelor's Thesis)
Supervisor name: Buwalda, B.
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 06 Jul 2018
Last Modified: 10 Jul 2018 05:52

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