Amygdala's involvement in facilitating associative learning-induced plasticity: a promiscuous role for the amygdala in memory acquisition

Abstract

It is widely accepted that the amygdala plays a critical role in acquisition and consolidation of fear-related memories. Some of the more widely employed behavioral paradigms that have assisted in solidifying the amygdala's role in fear-related memories are associative learning paradigms. With most associative learning tasks, a neutral conditioned stimulus (CS) is paired with a salient unconditioned stimulus (US) that elicits an unconditioned response (UR). After multiple CS-US pairings, the subject learns that the CS predicts the onset or delivery of the US, and thus elicits a learned conditioned response (CR). Most fear-related associative paradigms have suggested that an aspect of the fear association is stored in the amygdala; however, some fear-motivated associative paradigms suggest that the amygdala is not a site of storage, but rather facilitates consolidation in other brain regions. Based upon various learning theories, one of the most likely sites for storage of long-term memories is the neocortex. In support of these theories, findings from our laboratory, and others, have demonstrated that trace-conditioning, an associative paradigm where there is a separation in time between the CS and US, induces learning-specific neocortical plasticity. The following review will discuss the amygdala's involvement, either as a site of storage or facilitating storage in other brain regions such as the neocortex, in fear- and non-fear-motivated associative paradigms. In this review, we will discuss recent findings suggesting a broader role for the amygdala in increasing the saliency of behaviorally relevant information, thus facilitating acquisition for all forms of memory, both fear- and non-fear-related. This proposed promiscuous role of the amygdala in facilitating acquisition for all memories further suggests a potential role of the amygdala in general learning disabilities.

Breathe out and learn: Expiration‐contingent stimulus presentation facilitates associative learning in trace eyeblink conditioning

“…This could lead to a state of the nervous system that is more favorable for plasticity, such as enhanced SPW‐R activity in the hippocampus (Buzsáki, ; Nokia et al, ). In further studies, it would be interesting to investigate how respiration phase (or other bodily rhythms) affects, for example, neural activity in the amygdala, which also seems to play a significant role in TEBC (Büchel, Dolan, Armony, & Friston, ; Chau & Galvez, ).…”

Anatomy and computational modeling of networks underlying cognitive-emotional interaction

“…It has long been established that both emotional salience and direct stimulation in the amygdala promote memory formation (McGaugh, 2004; Chau and Galvez, 2012), a process which may involve the substantial projections from midbrain dopaminergic areas to amygdalar nuclei (Björklund and Dunnett, 2007; Cho and Fudge, 2010). Dopaminergic signals can serve as teaching signals that affect synaptic plasticity and memory, often in conjunction with other neurotransmitters (Nader and LeDoux, 1999; LaLumiere et al, 2004).…”

“…The amygdala can mediate widespread effects via projections to cortical areas (especially prefrontal cortex and the medial temporal lobe), as well as the striatum, nucleus accumbens, thalamus, hypothalamus, and the neurotransmitter systems (Cardinal et al, 2002; Whalen and Phelps, 2009), i.e., the cholinergic, dopaminergic, noradrenergic, and serotonergic structures. Within the forebrain, these projections are strongly implicated in attention, learning, and memory (e.g., Kilgard and Merzenich, 1998; Bao et al, 2001; McGaugh, 2004; Hasselmo, 2006; Parikh and Sarter, 2008; Miasnikov et al, 2009; Ramanathan et al, 2009; Froemke and Martins, 2011; Chau and Galvez, 2012; Medalla and Barbas, 2012). …”

Dysfunctional or hyperfunctional? The amygdala in posttraumatic stress disorder is the bull in the evolutionary China shop

“…Thus, the amygdala is critically involved in different forms of instinctual and learned fear and in modulating attention to fear-related stimuli as well as fear recognition and perception. Although the scope of information that is processed by the amygdala is not limited to fear-provoking cues (Burgdorf and Panksepp, 2006;Berridge et al, 2010;Pessoa, 2010;Markowitsch and Staniloiu, 2011;Chau and Galvez, 2012;Fernando et al, 2013;Hermans et al, 2014), extensive research suggests that fear-provoking stimuli are prominently featured in the domain of amygdala functioning (Phillips et al, 1998;Phelps and LeDoux, 2005;Johansen et al, 2012).…”