A Pharmacological Analysis of an Associative Learning Task: 5-HT₁to 5-HT₇Receptor Subtypes Function on a Pavlovian/Instrumental Autoshaped Memory

Abstract

Recent studies using both invertebrates and mammals have revealed that endogenous serotonin (5-hydroxytryptamine [5-HT]) modulates plasticity processes, including learning and memory. However, little is currently known about the mechanisms, loci, or time window of the actions of 5-HT. The aim of this review is to discuss some recent results on the effects of systemic administration of selective agonists and antagonists of 5-HT on associative learning in a Pavlovian/instrumental autoshaping (P/I-A) task in rats. The results indicate that pharmacological manipulation of 5-HT 1-7 receptors or 5-HT reuptake sites might modulate memory consolidation, which is consistent with the emerging notion that 5-HT plays a key role in memory formation.

Role of GSK3<i>β</i> and PP2A on Regulation of Tau Phosphorylation in Hippocampus and Memory Impairment in ICV-STZ Animal Model of Alzheimer’s Disease

“…After a number of such presentations, the animal approaches the CS and presents instrumental responses (conditioned response [CR]), such as peck, nose-poke, and lever-press responses. Then, CR or autoshaped responses result from the S-S association and are sustained by response-stimulus (R-S) association [35]. Importantly, within the continued progress of behavioral memory tasks development, a Pavlovian/Instrumental autoshaping (P/I-A) task combines both Pavlovian and instrumental conditioning; which offers the opportunity to study hippocampus-mediated declarative memory and striatum-mediated R-S "habit formation" [36].…”

“…The latest is quite important, as it allows the study of bidirectional expression of an enhanced or impaired memory formation. P/I-A clearly separates training for testing sessions, and it has been useful to detect changes in memory formation elicited by drugs or aging [35].…”

“…The criterion was that once the animal ate all 50 food-pellets and presented 150 nose-pokes (as measured by a photocell) into the food-magazine, the autoshaping training program was initiated [35] [37]. The autoshaping program had been reported previously [37] [38], and this consisted of discrete trials.…”

The Serotonin1AReceptor Partial Agonist S15535 [4-(Benzodioxan-5-yl)1-(indan-2-yl)piperazine] Enhances Cholinergic Transmission and Cognitive Function in Rodents: A Combined Neurochemical and Behavioral Analysis

“…Correspondingly, the aim of the present work was to characterize the influence of S15535, a selective partial agonist at 5-HT 1A receptors (Millan et al, 1994(Millan et al, , 1997aNewman-Tancredi et al, 1999, 2003, upon cholinergic transmission and cognitive-attentional function in rodents. First, using a dialysis procedure not requiring the use of AChEIs (Ichikawa et al, 2002;Gobert et al, 2003), we evaluated the influence of S15535 upon extracellular levels of ACh in the FCX and dorsal hippocampus (DH).…”

Regulation of serotonin levels by multiple light-entrainable endogenous rhythms

“…The decrease in serotonin levels during the early subjective morning hours coincides with the onset of a low activity period in lobsters (Ennis, 1983;Chabot et al, 2001). The fact that serotonin has been repeatedly associated with learning and memory mechanisms (Harvey, 2003;Meneses, 2003;Orsetti et al, 2003;Wolff et al, 2003) may also be relevant to the rhythms we measure in brain regions. Certainly, the fact that serotonin is differentially regulated in specific brain regions may reflect the potential importance of time-ofday performance of those areas.…”