Thyroid hormones are modulators of cognitive functions, and changes in
hormone levels affect intelligence, memory, attention and executive
function. Single nucleotide polymorphisms (SNPs) of transporter proteins
MCT8, MCT10 and deiodinase 2 (DIO2) influence thyroid metabolism and could
therefore contribute to inter-individual variance of cognitive functions.
This study investigates the influence of these SNPs using an extensive
neuropsychological test battery. 656 healthy participants aged 18–39
years were genotyped for four SNPs: MCT8 (rs5937843 and rs6647476), MCT10
(rs14399) and DIO2 (rs225014) and underwent eleven different
neuropsychological tests as well as four personality questionnaires. Test
results were compared between homo- and heterozygous carriers and for the
X-linked MCT8 additionally between men and women. Personality questionnaires
revealed that Risk Seeking was reduced in homozygous T carriers and highest
in homozygous C carriers of the DIO2 SNP and that both polymorphisms of MCT8
had an additive effect on Physical Aggression in men. Neuropsychological
testing indicated that MCT10 affects nonverbal reasoning abilities, DIO2
influences working memory and verbal fluency and MCT8 influences attention,
alertness and planning. This pilot study suggests an influence of
polymorphisms in thyroid hormone transporter genes and deiodinase on
cognitive domains and personality traits.
Background
Increasing familiarity and practice might free up mental resources during laparoscopic surgical skills training. The aim of the study was to track changes in mental resource allocation during acquisition of laparoscopic surgical skills.
Methods
Medical students with no previous experience in laparoscopic surgery took part in a 5-week laparoscopic training curriculum. At the beginning and end of the training period, one of the training tasks was combined with a secondary auditory detection task that required pressing a foot switch for defined target tones, creating a dual-task situation. During execution of the two concurrent tasks, continuous electroencephalographic measurements were made, with special attention to the P300 component, an index of mental resources. Accuracy and reaction times of the secondary task were determined.
Results
All 14 participants successfully completed the training curriculum. Target times for successful completion of individual tasks decreased significantly during training sessions (P <0.001 for all tasks). Comparing results before and after training showed a significant decrease in event-related brain potential amplitude at the parietal electrode cluster (P300 component, W = 67, P = 0.026), but there were no differences in accuracy (percentage correct responses: W = 48, P = 0.518) or reaction times (W = 42, P = 0.850) in the auditory detection task.
Conclusion
The P300 decrease in the secondary task over training demonstrated a shift of mental resources to the primary task: the surgical exercise. This indicates that, with more practice, mental resources are freed up for additional tasks.
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