The Amygdaloid Body as the Anatomical Substrate of Emotional Memory: Implications in Health and Disease (original) (raw)
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How the amygdala affects emotional memory by altering brain network properties
Neurobiology of Learning and Memory, 2014
The amygdala has long been known to play a key role in supporting memory for emotionally arousing experiences. For example, classical fear conditioning depends on neural plasticity within this anterior medial temporal lobe region. Beneficial effects of emotional arousal on memory, however, are not restricted to simple associative learning. Our recollection of emotional experiences often includes rich representations of, e.g., spatiotemporal context, visceral states, and stimulus-response associations. Critically, such memory features are known to bear heavily on regions elsewhere in the brain. These observations led to the modulation account of amygdala function, which postulates that amygdala activation enhances memory consolidation by facilitating neural plasticity and information storage processes in its target regions. Rodent work in past decades has identified the most important brain regions and neurochemical processes involved in these modulatory actions, and neuropsychological and neuroimaging work in humans has produced a large body of convergent data. Importantly, recent methodological developments make it increasingly realistic to monitor neural interactions underlying such modulatory effects as they unfold. For instance, functional connectivity network modeling in humans has demonstrated how information exchanges between the amygdala and specific target regions occur within the context of large-scale neural network interactions. Furthermore, electrophysiological and optogenetic techniques in rodents are beginning to make it possible to quantify and even manipulate such interactions with millisecond precision. In this paper we will discuss that these developments will likely lead to an updated view of the amygdala as a critical nexus within large-scale networks supporting different aspects of memory processing for emotionally arousing experiences.
The amygdala modulates the consolidation of memories of emotionally arousing experiences
Annual Review of Neuroscience, 2004
Converging findings of animal and human studies provide compelling evidence that the amygdala is critically involved in enabling us to acquire and retain lasting memories of emotional experiences. This review focuses primarily on the findings of research investigating the role of the amygdala in modulating the consolidation of long-term memories. Considerable evidence from animal studies investigating the effects of posttraining systemic or intra-amygdala infusions of hormones and drugs, as well as selective lesions of specific amygdala nuclei, indicates that (a) the amygdala mediates the memory-modulating effects of adrenal stress hormones and several classes of neurotransmitters; (b) the effects are selectively mediated by the basolateral complex of the amygdala (BLA); (c) the influences involve interactions of several neuromodulatory systems within the BLA that converge in influencing noradrenergic and muscarinic cholinergic activation; (d) the BLA modulates memory consolidation via efferents to other brain regions, including the caudate nucleus, nucleus accumbens, and cortex; and (e) the BLA modulates the consolidation of memory of many different kinds of information. The findings of human brain imaging studies are consistent with those of animal studies in suggesting that activation of the amygdala influences the consolidation of long-term memory; the degree of activation of the amygdala by emotional arousal during encoding of emotionally arousing material (either pleasant or unpleasant) correlates highly with subsequent recall. The activation of neuromodulatory systems affecting the BLA and its projections to other brain regions involved in processing different kinds of information plays a key role in enabling emotionally significant experiences to be well remembered.
The Possible Contribution of the Amygdala to Memory
Behavioural Neurology, 1993
The processing of episodic memories is believed to depend on the proper functioning of so-called bottleneck structures through which information apparently must pass in order to be stored long term. These regions are seen in the basal forebrain, the medial diencephalon, and the medial temporal lobe. We here report a case with circumscribed bilateral temporal lobe damage, principally involving the amygdaloid area. Neuropsychological investigation demonstrated preserved intelligence, intact general memory and several other undisturbed cognitive functions, but a specific, affect-related, memory disorder. We conclude from these findings that the role of the amygdala is to process mnemonic events in a way that a specific emotional significance can be found and reactivated. Therefore it is suggested that the amygdala is likely to be a bottleneck structure for affect-related long-term memory functions.
Neuroimage, 2003
Considerable evidence from both animal and human subject research supports the hypothesis that the amygdala, when activated by emotional arousal, modulates memory storage processes in other brain regions. By this hypothesis, changes in the functional interactions of the amygdala with other brain regions during emotional conditions should underlie, at least in part, enhanced memory for emotional material. Here we examined the influence of the human amygdala on other brain regions under emotional and nonemotional learning conditions using structural equation modeling (SEqM). Eleven male subjects received two PET scans for regional cerebral glucose metabolism-one scan while viewing a series of emotionally provocative (negative) film clips and a second scan while viewing a series of more emotionally neutral film clips. Enhanced activity in the right amygdala was related to enhanced memory for the emotional films. To identify potential candidate voxels for SEqM, the functional connectivity of the maximally activated voxel within the right amygdala was investigated using partial least squares. A subset of regions identified by this analysis showing differences functional connectivity with the amygdala between the emotional versus neutral film conditions were then submitted to SEqM, which revealed significantly increased amygdala influences on the ipsilateral parahippocampal gyrus and ventrolateral prefrontal cortex during the emotional relative to the neutral film viewing condition. These findings support the view that increased influences from the amygdala, presumably reflecting its memorymodulation function, occur during emotionally arousing learning situations.
Amygdala and Emotional Modulation of Multiple Memory Systems
The Amygdala - Where Emotions Shape Perception, Learning and Memories
Stress and anxiety can either enhance or impair memory, and the direction of the effect partially depends on the type of memory being affected. Behavioral or pharmacological stressors typically impair cognitive memory mediated by the hippocampus, but enhance stimulus-response habit memory mediated by the dorsolateral striatum. Evidence also indicates that the effect of emotion on different kinds of memory critically depends on a modulatory role of the basolateral amygdala (BLA). BLA modulation of multiple memory systems may be achieved through its glutamatergic projections to other brain regions, which may enhance stress hormone activity, modulate competition between memory systems, and alter synaptic plasticity. The neurobiology underlying the emotional modulation of multiple memory systems may be relevant to understand the impact of emotional arousal on the development and expression of human psychopathologies characterized by maladaptive habitual behaviors (e.g., drug addiction and relapse).
Functional activities of the amygdala: an overview
Journal of psychiatry & neuroscience : JPN, 2000
Research to date into the amygdala shows that it has an integrative role in behavioural, vegetative and endocrine activities of animals in their relation with their environment. Animal studies show that amygdala has a role in emotional response, integrating input signals and initiating activities related to them. Different nuclei seem to have different effects. A complete picture of the functional roles of the amygdala is unavailable, and it has been suggested that the amygdala is functionally and anatomically heterogeneous. Amygdaloid subnuclei appear to have a role in the modulation of fear, in memory and attention, and in some sexual and sex-related behaviour of rats. In humans, functional magnetic resonance imaging shows that the amygdala responds preferentially to emotionally charged stimuli. Bilateral amygdala damage in humans can compromise the recognition of fear in facial expressions, an important ability in social judgement. Future study of the amygdala promises to shed li...