Role of serotoniergic system Flashcards
Forebrain 5-HT depletion disinhibits punished responding
Tye and colleagues
Brain 5-HT systems are known to mediate acute responding to punishment. This study investigated 5-HT involvement in learned resistance to punishmend.
Forebrain 5-HT was depleted by intracerebral injection of 5,7-dihydroxytryptamine.
- Lesioned rats were fully able to learn resistance to punishment, although acute responding to punishment was impaired.
Thus forebrain 5-HT does not mediate learned resistance to punishment
Davis and Gray 1983
Examined performance of healthy male volunteers on executive tasks following transient reduction of central 5-HT levels via method of acute tryptophan depletion.
15 healthy males, within-subject, double-blind, counterbalanced crossover study.
WCST, Stroop, verbal fluency, trail making. Visual analogue scales used to assess mood.
Improvement in simple motor speed/attention- in keeping with ascribed role of 5-HT in the cortex, although executive function is not robustly altered.
Presence of interaction effects suggested that subtle changes may occur but are masked, possibly by simple learning effects.
Gallagher et al 2003
Selective serotonin depletion in the orbito-frontal PFC of marmosets.
Used a serial discrimination reversal paradigm.
Marmosets trained preopertively on two discriminations, before recieving either multiple 5,7-DHT injections through the PFC or a sham control proceedure. Postoperatively, retested on the retention of the discrimination, on the acquisition of a novel discrimination, and then on four reversals.
Postoperatively, lesion had no effect on ability to remember previously learned visual discrimination or acquire a new discrimination. However, upon reversal of the reward contingency, lesioned monkeys made significantly more errors than controls.
Highlights importance of serotonin in behavioral flexibility, highly relevant to OCD, schizophrenia, and the cognitive sequaelae of drug abuse in which preservation is prominent.
Clarke et al 2004
