Description
- Abstract:
- Introduction: Glutamate (Glu) is the major excitatory neurotransmitter in the brain, yet its direct contributions to subjective experience in healthy humans have yet to be explored. Research involving glutamatergic antagonists’ effects on subjective experiences in clinical populations and animal models has been well established, demonstrating a relationship between Glu and positive emotion. Thus, we hypothesized that Glu agonist, i.e. psychostimulant, induced changes in glutamatergic compounds would be positively associated with positive affective states. Methods: Using 1H MRS, we recorded drug induced changes in glutamatergic compounds, such as Glu, glutamate and glutamine (pooled as Glx), glutamine (Gln), creatine (tCr), myo-inositol (Ins), and choline (Cho), in the dorsal anterior cingulate cortex (dACC) of healthy male and female adults (M = 22.3 years). In a placebo-controlled, double-blinded, within-subjects crossover design, healthy participants (N = 26) were administered single clinically relevant doses of d amphetamine (AMP; 20 mg), methamphetamine (MA; Desoxyn®, 20 mg), and placebo (PBO) on three separate test days, each serving as their own control. At 140-150 m post ingestion, 1H MRS was conducted in the dACC. Self report measures of subjective experience were administered outside the scanner 15 mins before taking the capsule and at half hour intervals after ingestion, for a total of eight completion points during each test session. Results: Using principal components analysis, four AMP induced subjective experiences in comparison to PBO: Activated Positive Affect, Somatic Sensations, Activated Negative Affect, and Anxious Distress. We also found three MA induced effects in comparison to PBO: Activated Positive Affect, Activated Negative Affect, and Somatic + Low Negative Affect. In females, AMP-induced changes in Glu were significantly correlated with activated positive affect, r = .609, p < .05, and aversive Somatic Sensations were negatively correlated with AMP-induced changes in tCr, r = -.721, p < .01, and duration of drug liking, r = -.806, p < .01. In males, a negative association was found between AMP induced changes in Gln and Activated Negative Affect, r = -.624, p < .05. Similarly in females, MA induced changes in Gln were negatively related to Activated Negative Affect, r = -.705, p < .05. AMP induced changes in Gln were positively related to Anxious Distress in females, r = .613, p < .05. Conclusions: These findings corroborate the literature on heightened responsivity to the subjective emotional impact of changes in glutamatergic compounds after psychostimulant exposure in females. Future studies should investigate the relationship between ovarian hormones and psychostimulant-induced changes in glutamatergic compounds.
- Notes:
- Thesis (Sc. M.)--Brown University, 2018
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Citation
Gonsalves, Meghan Anne,
"The Relationship Between Neocortical 1H MRS Metabolites and Subjective Experience in Healthy Adults"
(2018).
Public Health Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.26300/8h4g-zd75
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Public Health Theses and Dissertations
Theses and Dissertations for the Public Health department....