Sex dependency and genetic modulation of emotional processing and memory : a behavioural and imaging study

Emotional processing and episodic memory are topics of great interest in neuroscience
research. It is known that both of these two cognitive processes can be influenced by a variety
of factors. The scope of this thesis is to highlight the importance and describe the role of two
of these factors, namely sex and genetics. Our investigation on this topic consists of results
that have been reported in five peer-reviewed publications, where methods from different
disciplines like neuroimaging, psychoneuroendocrinology, and epigenetics were combined.
In order to assess sex-dependent differences in emotional processing and episodic
memory, we conducted (in our first publication) behavioural and imaging analyses within a
large sample of healthy young subjects. Our results point to differences between the sexes in
emotional appraisal as well as setting-dependent differences in memory performance of
pictorial information, which seem to be independent of each other. We additionally
investigated the modulatory character of endogenous testosterone levels on emotional
processing and memory (in the second publication). The results may suggest a role of
testosterone in enhancing memory performance for neutral stimuli by increasing the
biological salience of this information, as indicated by increased arousal ratings and amygdala
reactivity to these stimuli.
To further investigate the genetic modulation of emotional processing and episodic
memory we focused on the role of three genes (neurotrophic tyrosine kinase receptor type 2
(NTRK2), protein kinase C alpha (PRKCA) and brain derived neurotrophic factor (BDNF)).
We provided (in out third publication) evidence for a role of a NTRK2 variant in the emotion
processing of positive stimuli in healthy young subjects and additionally found NTRK2-
dependent differences in white matter measures as well as methylation levels. In reference to
episodic memory, we found (in the fourth publication) that PRKCA plays a role in memory
performance of healthy subjects and is also associated with specific symptoms of
posttraumatic stress disorder (PTSD) as well as the risk to develop PTSD in genocide
survivors. Finally (in the fifth publication), by combining original data with meta-analytic
techniques, we found no association between a genetic variant of the BDNF gene and
hippocampal volumes in our original data and show that the weak association in the meta-
analysis is moderated by measuring techniques, publication year and sample size.
Taken together, these results support the presence of sex-dependent differences in
emotional processing as well as episodic memory and emphasize the role of specific genes in
these processes.