Molecular Signals into the Insular Cortex and Amygdala During Aversive Gustatory Memory Formation

Abstract

In this paper, we will provide evidence of the putative molecular signals and biochemical events that mediate the formation of long-lasting gustatory memory trace. When an animal drinks a novel taste (the conditioned stimulus; CS) and it is later associated with malaise (unconditioned stimulus; US), the animal will reject it in the next presentation, developing a long-lasting taste aversion, i.e., the taste cue becomes an aversive signal, and this is referred to as conditioning taste aversion. Different evidence indicates that the novel stimulus (taste) induces a rapid and strong cortical acetylcholine activity that decreases when the stimulus becomes familiar after several presentations. Cholinergic activation via muscarinic receptors initiates a series of intracellular events leading to plastic changes that could be related to short- and/or long-term memory gustatory trace. Such plastic changes facilitate the incoming US signals carried out by, in part, the glutamate release induced by the US. Altogether, these events could produce the cellular changes related to the switch from safe to aversive taste memory trace. A proposed working model to explain the biochemical sequence of signals during taste memory formation will be discussed.

Acute suppression, but not chronic genetic deficiency, of c- fos gene expression impairs long-term memory in aversive taste learning

“…Lamprecht et al (35) also showed that inhibition of cAMP response element-binding protein (CREB), one of the regulatory transcriptional factors for c-fos gene expression, in the AMY with in vivo AS-ODN technology disrupted the retention, but not the acquisition, of CTA. In line with these results, Bermudez-Rattoni and colleagues (36,37) have suggested that positive interaction between the basolateral AMY-IC enhances the strength of long-term CTA memory.…”

False beliefs about fattening foods can have healthy consequences

“…Humans and other animals can be conditioned to avoid food. Such conditioned taste aversion leads to many documented changes in the brain, in particular, changes in cholinergic and glutamatergic activity (23). It is unclear whether false food beliefs and their accompanying food avoidance, like those observed here, produce neural reorganization similar to that evident with true memories of bad food experiences (24,25).…”

mGluR7 facilitates extinction of aversive memories and controls amygdala plasticity

“…Thus the use of CTA, allows the investigation of the processes involved in both the acquisition and extinction of aversive memories. 30,35 We have established that BALB/c mice are a useful strain for assessing CTA, 36 so we used this strain for our initial pharmacological studies. Also, the time course of extinction in this mouse strain is relatively long (approximately 4-5 days) and, therefore, amenable to assess potential facilitatory responses.…”