Modulation of memory storage

“By contrast, acute mild stress exposure has no effect on or can actually improve the memory consolidation functions of the hippocampus and the amygdal”

“Cahill and McGaugh (1996) have shown that when a person is administered propranolol, emotional situations that would normally be given preferential treatment in perception and memory are processed in an emotionally flat manner.”

“Pharmacological studies have provided evidence that noradrenaline, interacting with other neuromodulators and hormones, modulates memory formation, mainly through actions in the amygdala and the hippocampus (see ref”

“Moreover, very low, very high, or chronically elevated levels of catecholamines and glucocorticoids appear to have disruptive effects on memory processes [188,199,202,204,264,269,270] and this adds complexity to the interpretation of affective influences on memory.”

“A second view relates to the manner in which the strength of memory representations in a given brain area are modulated as a result of activity from other areas or hormonal influence”

“For example, infusion of β adrenergic antagonists into the amygdala impairs, whereas infusion of a β adrenergic agonist improves memory consolidation (reviewed in (Cahill & McGaugh, 1996).”

“This enhanced memory for emotional events has been attributed to interactions between the amygdala and other neural areas such as the hippocampus and prefrontal cortex (PFC) ( Cahill & McGaugh, 1996 ).”

“In contrast to the PFC, uncontrollable stressors such as upsetting images increase the ability of the amygdala to enhance consolidation of the memory of the stressful event, a mechanism that has been documented in both animals and humans (Cahill and McGaugh, 1996).”

“…findings go together with the behavioral and electrophysiological evidence indicating that the long-term acquisition of information is severely dampened if not blocked during sleep (Tononi and Cirelli, 2000), whereas it is facilitated by an increase in arousal levels (Cahill and McGaugh, 1996).”

“Such emotional cues can engage multiple psychological processes, including attention and associability, the effectiveness of memory consolidation, pavlovian arousal, and goal-directed action (Dickinson and Balleine, 1994; Cahill and McGaugh, 1996; Holland, 1997; Killcross et al., 1997; Holland and Gallagher, 1999; Par…”

“Most of the work on stress and cognition has looked at memory, finding that intrinsic emotion affects memory in an inverted-Ushaped fashion (e.g., Cahill & McGaugh, 1996; Joseph, 1999; Van Londen et al., 1998).”

“In general, the noradrenaline signal is thought to be involved in sensory processing, decision-making, working memory, and memory formation (Cahill and McGaugh, 1996; Robbins and Roberts, 2007). acetylcholIne Cholinergic neurons in the basal forebrain nuclei are activated during arousal and…”

“Substantial evidence from animal experiments indicates that enhanced memory associated with emotional experiences involves activation of the β-adrenergic system (Introini-Collison et al. 1992; Packard et al. 1995; Cahill and McGaugh 1996 ).”

“Emotional arousal induced by aversive stressors results in adrenalin (epinephrine) and cortisol (glucocorticoids) release from the adrenal glands (Cahill and McGaugh, 1996; Cahill et al., 1994; McIntyre et al., 2012).”

“Many reviews have reported that the amygdala is involved in highly aversive conditions and is considered part of the repertoire of emotional responses (Cahill, 2000; Cahill & McGaugh, 1996; LeDoux, 2000).”

“Emotionally arousing situations can modulate this process of memory consolidation [Cahill and McGaugh, 1996].”

“Memory bias refers to the fact that events associated with positive or negative emotions are more readily remembered than neutral events, and includes memory storage, consolidation and retrieval processes (Cahill and McGaugh, 1996; Hamann et al., 1999).”

“Thus the present findings are consistent with a large number of studies examining the role of the BLC in memory consolidation in both rats and humans (Cahill and McGaugh, 1998; McGaugh et al., 1999).”

“Although memory is affected by stress, the relationship is not always straightforward, and it is important to consider that stress-reactivity is no longer conceptualized as a simple relationship (Cahill and McGaugh, 1996).”

“Hence, brain mechanisms have evolved for storing information that reflects the degree to which the information is worth storing (13).”

“A wide array of studies focused on the eVect of these stress hormones (nor) adrenaline and cortisol on memory performance in animals and humans ( Cahill & McGaugh, 1996; Lupien et al., 2005a; McGaugh, 2004; van Stegeren, Everaerd, Cahill, McGaugh, & Gooren, 1998) and on the mechanisms and structures involved in this p…”

“One manner by which the amygdala carries out this critical function is by modulating mnemonic processes (3).”

“Memories for emotionally charged events tend to be stronger and more persistent ( Cahill and McGaugh, 1996; McGaugh and Roozendaal, 2002).”

“A number of studies suggest that the level of arousal may underlie emotional enhancement [7,8,33,42,43].”

“Amygdala activity modulates the strength of emotional memories (Cahill and McGaugh, 1996), possibly by facilitating cortical processing during salient learning events (Armony et al., 1998; Paz et al., 2006).”

“A number of hypotheses have been proposed suggesting that the amygdala may modulate mnemonic and attentional processing in cortical areas (Kapp et al., 1992; Rolls, 1992; Gallagher and Holland, 1994; McGaugh et al., 1995; Packard et al., 1995; Weinberger, 1995; Cahill and McGaugh, 1996; Armony et al., 1997b).”

“In the amygdala, stress-induced stimulation of alpha-1 (Ferry, Roozendaal, & McGaugh, 1999) and beta-1 (Cahill & McGaugh, 1996; Debiec & LeDoux, 2006; Ferry & McGaugh, 1999; Introini-Collison, Miyazaki, & McGaugh, 1991; Roozendaal, Quirarte, & McGaugh, 2002) receptors strengthens its function, for…”

“An enhanced learning of emotional compared to neutral material (Cahill and McGaugh, 1995, 1996; LaBar and Cabeza, 2006) is related to the activation of the amygdala resulting from a noradrenergic input from the brain stem into the basolateral nucleus (Cahill et al., 1994; McGaugh et al., 1996;…”

“Interestingly, these hormones are reported to enhance instrumental learning when injected either systemically or directly into the amygdala, and the enhancement is prevented by lesions to the basolateral nucleus (Cahill and McGaugh 1996; Roozendaal and McGaugh 1997).”

“Other potential mediating mechanisms for the observed effects of nutrients on mood and simple cognitive functions are changes in the energy supply to nerve cells and fluctuations in plasma metabolite or hormone levels [5,17,31].”

“These findings are consistent with the hypothesis that emotional responses influence memory, at least in part, through amygdala by modulating long-term memory storage (Bianchin, Mello-e-Souza, Medina, & Izquierdo, 1999; Cahill & McGaugh, 1996).”

“The amygdalae are well known to act as modulators of emotional memory (Cahill and McGaugh 1996, 1998) while the hippocampi are more generally engaged in declarative memory functions, irrespective of emotion processing (Nadel and Moscovitch 1997; Squire 1992).”

“…contributes to numerous brain functions, including arousal, sensory-motor processing, attention, learning, and memory (Jouvet, 1969; Harley, 1987; Cahill and McGaugh, 1996; Berridge and Waterhouse, 2003; Aston-Jones and Cohen, 2005; Sara, 2009; Carter et al., 2010; Howells et al., 2012; Sara…”

“Cahill & McGaugh, 1996; Cahill, Prins,Weber,&McGaugh,1994).”

“Improved cognitive functioning as a consequence of an optimal state of metabolic activation or arousal was reported by others (Nielson & Jensen, 1994; Cahill & McGaugh, 1996; Fery et al. 1997), and an ‘inverted U’-shaped relationship was discussed (Davis et al. 1996; Fery et al. 1997).”

“edu siderable support for the hypothesis that peripheral stress hormones released during an emotionally arousing event influence memory storage processes for the event (Cahill and McGaugh, 1996 ; Gold et al., 1995 ; McGaugh, 1989).”

“Furthermore, post-learning interferences of newly formed memory with electroconvulsive shock or protein synthesis blockers also modulate or disrupt LTM, but leave STM intact (7).”

“Infusion of a β-adrenergic receptor agonist improves memory consolidation (Cahill and McGaugh, 1996) and systemic propranolol impaired memory retrieval on a water maze spatial task (Murchison et al.”

“The subsequent longitudinal study could widely replicate our cross-sectional results and – like Ennemoser and Schneider (2007) or Hancox et al.”

“Presumably, the stimulation of peripheral -adrenergic receptors during emotionally arousing events modulates the HR changes (Cahill and McGaugh, 1996).”

“…role in the modulation of emotional memories – via its interaction with other MTL regions – has been well established (Gallagher and Chiba, 1996; Cahill and McGaugh, 1998; Kensinger and Schacter, 2006), and although its role has been investigated more thoroughly for memories that are…”

“Using an inhibitory avoidance procedure in animals, McGaugh and colleagues have shown that administration of propranolol, a b-adrenergic blocker, prior to, or immediately after, training inhibited the enhancement effects of norepinephrine on memory consolidation (Cahill and McGaugh, 1996; Miranda et al., 2003; Salinas…”

“His conclusions are informed by Cahill and McGaugh (1998), who examined how arousal and stress impacted hormones and glucose levels, and ultimately learning.”

“They also experience neuron loss in the amygdala (6, 7), a brain structure involved in emotion and the modulation of memory by exposure to emotional events (8-10).”

“Indeed neural substrates for feeling states initially formed subcortically are sufficient for retrieval, despite their long-term storage in the cortex (Cahill and MacGaugh, 1996).”

“…or stress are beneficial for strengthening memory up to an optimal level, after which, however, an additional rise in stress leads to a decrease or loss of memory (Cahill and McGaugh, 1996; Diamond et al., 2007; Sandi and PineloReceived Feb. 25, 2015; revised Sept. 22, 2015; accepted Oct. 22, 2015.”

“Some data suggest that the main role of the amygdala would be to actually modulate memories laid down in the hippocampus and other places, particularly the caudate nucleus (Cahill & McGaugh, 1996; McGaugh et ai., 1995).”

“M maintenance or persistence depends on the degree of emotional arousal present at the time of consolidation (1, 2), and apparently on several different biochemical and behavioral variables over the next several hours or days (3–9), especially in the hippocampus, which is widely recognized as the region in charge of c…”

“Inhibitory avoidance is strongly modulated by the basolateral amygdala (BLA) in the Wrst few minutes of consolidation (Bianchin, Mello e Souza, Medina, & Izquierdo, 1999; Cahill & McGaugh, 1996).”