The amygdala is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain's cerebrum in complex vertebrates, including humans. Shown to perform a primary role in the processing of memory, decision making, and emotional responses, the amygdalae are considered part of the limbic system. The term "amygdala" was first introduced by Karl Friedrich Burdach in 1822.
The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.
The mesolimbic pathway, sometimes referred to as the reward pathway, is a dopaminergic pathway in the brain. The pathway connects the ventral tegmental area in the midbrain to the ventral striatum of the basal ganglia in the forebrain. The ventral striatum includes the nucleus accumbens and the olfactory tubercle.
Pavlovian fear conditioning is a behavioral paradigm in which organisms learn to predict aversive events. It is a form of learning in which an aversive stimulus is associated with a particular neutral context or neutral stimulus, resulting in the expression of fear responses to the originally neutral stimulus or context. This can be done by pairing the neutral stimulus with an aversive stimulus. Eventually, the neutral stimulus alone can elicit the state of fear. In the vocabulary of classical conditioning, the neutral stimulus or context is the "conditional stimulus" (CS), the aversive stimulus is the "unconditional stimulus" (US), and the fear is the "conditional response" (CR).
The locus coeruleus (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system.
Explicit memory is one of the two main types of long-term human memory, the other of which is implicit memory. Explicit memory is the conscious, intentional recollection of factual information, previous experiences, and concepts. This type of memory is dependent upon three processes: acquisition, consolidation, and retrieval.
Dominique de Quervain is a Swiss neuroscientist. He is professor of neuroscience and director of the Division of Cognitive Neuroscience at the University of Basel, Switzerland. He is known for his pioneering research into the use of glucocorticoids (cortisol) in the treatment of PTSD and phobias. He is understood to have found a link between cortisol and forgetting, specifically that cortisol can inhibit memory retrieval. Furthermore, he is known for his contributions to the field of genetics of human memory.
The amygdalofugal pathway is one of the three major efferent pathways of the amygdala, meaning that it is one of the three principal pathways by which fibers leave the amygdala. It leads from the basolateral nucleus and central nucleus of the amygdala. The amygdala is a limbic structure in the medial temporal lobe of the brain. The other main efferent pathways from the amygdala are the stria terminalis and anterior commissure.
Michael Hasselmo is an American neuroscientist and professor in the Department of Psychological and Brain Sciences at Boston University. He is the director of the Center for Systems Neuroscience and is editor-in-chief of Hippocampus (journal). Hasselmo studies oscillatory dynamics and neuromodulatory regulation in cortical mechanisms for memory guided behavior and spatial navigation using a combination of neurophysiological and behavioral experiments in conjunction with computational modeling. In addition to his peer-reviewed publications, Hasselmo wrote the book How We Remember: Brain Mechanisms of Episodic Memory.
The reward system is a group of neural structures responsible for incentive salience, associative learning, and positively-valenced emotions, particularly ones involving pleasure as a core component. Reward is the attractive and motivational property of a stimulus that induces appetitive behavior, also known as approach behavior, and consummatory behavior. A rewarding stimulus has been described as "any stimulus, object, event, activity, or situation that has the potential to make us approach and consume it is by definition a reward". In operant conditioning, rewarding stimuli function as positive reinforcers; however, the converse statement also holds true: positive reinforcers are rewarding.
The basolateral amygdala, or basolateral complex, consists of the lateral, basal and accessory-basal nuclei of the amygdala. The lateral nuclei receives the majority of sensory information, which arrives directly from the temporal lobe structures, including the hippocampus and primary auditory cortex. The basolateral amygdala also receives dense neuromodulatory inputs from ventral tegmental area (VTA), locus coeruleus (LC), and basal forebrain, whose integrity are important for associative learning. The information is then processed by the basolateral complex and is sent as output to the central nucleus of the amygdala. This is how most emotional arousal is formed in mammals.
Exceptional memory is the ability to have accurate and detailed recall in a variety of ways, including hyperthymesia, eidetic memory, synesthesia, and emotional memory. Exceptional memory is also prevalent in those with savant syndrome and mnemonists.
Memory consolidation is a category of processes that stabilize a memory trace after its initial acquisition. A memory trace is a change in the nervous system caused by memorizing something. Consolidation is distinguished into two specific processes. The first, synaptic consolidation, which is thought to correspond to late-phase long-term potentiation, occurs on a small scale in the synaptic connections and neural circuits within the first few hours after learning. The second process is systems consolidation, occurring on a much larger scale in the brain, rendering hippocampus-dependent memories independent of the hippocampus over a period of weeks to years. Recently, a third process has become the focus of research, reconsolidation, in which previously consolidated memories can be made labile again through reactivation of the memory trace.
The neuroanatomy of memory encompasses a wide variety of anatomical structures in the brain.
Activity-regulated cytoskeleton-associated protein is a plasticity protein that in humans is encoded by the ARC gene. The gene is believed to derive from a retrotransposon. The protein is found in the neurons of tetrapods and other animals where it can form virus-like capsids that transport RNA between neurons.
The cellular transcription factor CREB helps learning and the stabilization and retrieval of fear-based, long-term memories. This is done mainly through its expression in the hippocampus and the amygdala. Studies supporting the role of CREB in cognition include those that knock out the gene, reduce its expression, or overexpress it.
The management of traumatic memories is important when treating mental health disorders such as post traumatic stress disorder. Traumatic memories can cause life problems even to individuals who do not meet the diagnostic criteria for a mental health disorder. They result from traumatic experiences, including natural disasters such as earthquakes and tsunamis; violent events such as kidnapping, terrorist attacks, war, domestic abuse and rape. Traumatic memories are naturally stressful in nature and emotionally overwhelm people's existing coping mechanisms.
The effects of stress on memory include interference with a person's capacity to encode memory and the ability to retrieve information. Stimuli, like stress, improved memory when it was related to learning the subject. During times of stress, the body reacts by secreting stress hormones into the bloodstream. Stress can cause acute and chronic changes in certain brain areas which can cause long-term damage. Over-secretion of stress hormones most frequently impairs long-term delayed recall memory, but can enhance short-term, immediate recall memory. This enhancement is particularly relative in emotional memory. In particular, the hippocampus, prefrontal cortex and the amygdala are affected. One class of stress hormone responsible for negatively affecting long-term, delayed recall memory is the glucocorticoids (GCs), the most notable of which is cortisol. Glucocorticoids facilitate and impair the actions of stress in the brain memory process. Cortisol is a known biomarker for stress. Under normal circumstances, the hippocampus regulates the production of cortisol through negative feedback because it has many receptors that are sensitive to these stress hormones. However, an excess of cortisol can impair the ability of the hippocampus to both encode and recall memories. These stress hormones are also hindering the hippocampus from receiving enough energy by diverting glucose levels to surrounding muscles.
Parental experience, as well as changing hormone levels during pregnancy and postpartum, cause changes in the parental brain. Displaying maternal sensitivity towards infant cues, processing those cues and being motivated to engage socially with her infant and attend to the infant's needs in any context could be described as mothering behavior and is regulated by many systems in the maternal brain. Research has shown that hormones such as oxytocin, prolactin, estradiol and progesterone are essential for the onset and the maintenance of maternal behavior in rats, and other mammals as well. Mothering behavior has also been classified within the basic drives.
Stephen Andrew Maren is an American behavioral neuroscientist investigating the brain mechanisms of emotional memory, particularly the role context plays in the behavioral expression of fear. He has discovered brain circuits regulating context-dependent memory, including mapping functional connections between the hippocampus, prefrontal cortex, and amygdala that are involved in the expression and extinction of learned fear responses.
