Applications granted in 2022
- The Charismatic Brain: Do Charismatic Leaders Downregulate Followers’ Executive Network?
Lara Engelbert, Michiel van Elk, Mark van Vugt & Jan Theeuwes (scanning costs)
- Sex differences in the acute effect of guanfacine on prefrontal glutamate concentrations in individuals with an alcohol use disorder
Anne Marije Kaag & Mieke Schulte (scanning costs)
Review
While the prevalence of alcohol use disorder (AUD) is 2-3 times higher in men than in women, this gap is quickly closing. Moreover, women are suggested to be more prone to stress-related relapse compared to men, which is thought to be related to more severe impairments in prefrontal control over the amygdala. Consequently, treatment strategies that target prefrontal control could be specifically effective in the treatment of AUD in women. Guanfacine, an α2-adrenoreceptor agonist, is suggested to improve prefrontal control over the amygdala by suppressing glutamate transmission in the prefrontal cortex. Importantly, guanfacine has been shown to reduce stress-induced arousal and craving and to improve cognitive control in women but not men with a substance use disorder. Unfortunately, research examining sex differences in the working mechanisms of guanfacine in AUD is lacking.
Aim
Using the iBBA funding a 1H magnetic resonance spectroscopy scan was added to an already planned study, which allowed us to investigate the acute effects of guanfacine on dorsal anterior cingulate cortex (dACC) glutamate concentrations in individuals with an AUD, and to investigate sex-specific effects of guanfacine on dACC glutamate concentrations. It was hypothesized that guanfacine (compared to placebo) would decrease dACC glutamate concentrations and that this effect would be stronger in women compared to men.
30 cisgender men and 26 cisgender women with an AUD were scanned twice one week apart with 1H-MRS four hours following counterbalanced administration of a single dose of extended release guanfacine (2mg) and placebo in a single-blind, placebo-controlled cross-over design. Single-voxel localized spectra were collected from the bilateral dACC with point-resolved spectroscopy (PRESS) to measure Glx, a composite measure of glutamate and glutamine.
Preliminary analyses did not demonstrate a significant effect of guanfacine (versus placebo) on dACC Glx concentrations, nor was this effect moderated by sex. However, after correcting for medication order (guanfacine in the first session and placebo in the second, or the other way around) and BMI, a trend significant medication by BMI interaction was demonstrated, suggesting that guanfacine might increase, instead of decrease, Glx concentrations only in individuals with a higher BMI. subsequent exploratory analyses, controlling for BMI and medication order, furthermore demonstrated that in individuals with a longer history of alcohol use, guanfacine administration led to an increase of Glx in women, but a decrease in men. This effect was not seen in individuals with a shorter duration of regular use. Additional exploratory analyses with AUD symptom severity or daily alcohol intake did not reveal such significant interaction effects.
The current preliminary analyses do not provide evidence that guanfacine administration acutely decreases dACC glutamate concentrations in individuals with an AUD, or that this effect is stronger in women compared to men. On the contrary, exploratory analyses suggest that guanfacine (compared to a placebo) decreases dACC glutamate concentrations in men only, while it increases dACC glutamate concentrations in women. Speculatively, higher BMI scores in the current sample might be indicative of more several overall addictive behaviour, including overeating. As such, the significant effects found specifically in individuals with higher BMIs, might reflect the hypothesis that guanfacine is specifically effective in individuals with more severe addiction profiles. We are currently working on optimization the MRS preprocessing protocol, to improve the quality of the individual MRS spectra, before proceeding with the publication of these findings
- The Arrow of Time: Predictive Processing Based On World Knowledge
Tomas Knapen & Heleen Slagter (scanning costs)
Review
Extensive sampling of neural activity during rich cognitive phenomena is critical for robust understanding of brain function. To this end, we introduce the Arrow of Time dataset, a novel resource that captures high-resolution functional magnetic resonance imaging (fMRI) responses to thousands of richly annotated short (2.5s) naturalistic videos.
Extensive sampling of neural activity during rich cognitive phenomena is critical for robust understanding of brain function. To this end, we introduce the Arrow of Time dataset, a novel resource that captures high-resolution functional magnetic resonance imaging (fMRI) responses to thousands of richly annotated short (2.5s) naturalistic videos.
The dataset is generated using whole-brain 7 Tesla fMRI optimized for SNR.
This type of high-quality fMRI data allows for rigorous testing and refinement of models related to brain function and cognition. As a reusable resource, the Arrow of Time dataset will help elucidate the neural basis of naturalistic visual processing in the hands of researchers in the fields of cognitive neuroscience, psychology, and artificial intelligence.