Almond | Define Almond at Dictionary.com Share almond [ah-muh nd, am-uh nd; spelling pronunciation al-muh nd] /ˈɑ mənd, ˈæm ənd; spelling pronunciation ˈæl mənd/ Spell noun 1. the nutlike kernel of the fruit of either of two trees, Prunus dulcis (sweet almond) or P. dulcis amara (bitter almond) which grow in warm temperate regions. 2. anything shaped like an almond, especially an ornament. adjective of the color, taste, or shape of an almond. 6. made or flavored with almonds: almond cookies. Latin 1250-1300 1250-1300; Middle English almande < Old French (dial.) alemande, probably by transposition of -la < Late Latin amandula, with assimilative replacement of the unfamiliar cluster and adaptation to a known suffix, representing Latin amygdala < Greek amygdálē; replacing Old English amigdal < Latin Related forms Examples from the Web for almond Expand Declining bee populations may lead to significant agricultural losses in U.S.

Miranda Green May 7, 2013 Historical Examples The truth is that the candle in question is made out of a piece of apple, with a small peg cut from a nut or almond for a wick. Earl Hubert's Daughter Emily Sarah Holt almond meal is sometimes used as an adulterant in ipecacuanha powder. The Dead Command Vicente Blasco Ibez Cut the turnips in pieces four times the size of an almond, and put to boil in salt water. British Dictionary definitions for almond Expand noun 1. a small widely cultivated rosaceous tree, Prunus amygdalus, that is native to W Asia and has pink flowers and a green fruit containing an edible nutlike seed 2. the oval-shaped nutlike edible seed of this plant, which has a yellowish-brown shell 3. (modifier) made of or containing almonds: almond cake, related adjectives amygdaline amygdaloid 4. (as adjective): an almond skirt 6.

anything shaped like an almond nut Word Origin C13: from Old French almande, from Medieval Latin amandula, from Latin amygdala, from Greek amugdalē Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Word Origin and History for almond Expand n. c.1300, from Old French almande, amande, from Vulgar Latin *amendla, *amandula, from Latin amygdala (plural), from Greek amygdalos "an almond tree," of unknown origin, perhaps a Semitic word. Altered in Medieval Latin by influence of amandus "loveable," and acquiring in French an excrescent -l- perhaps from Spanish almendra "almond," which got it via confusion with the Arabic definite article al-, which formed the beginnings of many Spanish words.

Applied to eyes shaped like almonds, especially of certain Asiatic peoples, from 1870. Online Etymology Dictionary, © 2010 Douglas Harper almond in the Bible Expand a native of Syria and Palestine. In form, blossoms, and fruit it resembles the peach tree. Its blossoms are of a very pale pink colour, and appear before its leaves. Its Hebrew name, _shaked_, signifying "wakeful, hastening," is given to it on account of its putting forth its blossoms so early, generally in February, and sometimes even in January. In Eccl. 12:5, it is referred to as illustrative, probably, of the haste with which old age comes. There are others, however, who still contend for the old interpretation here. "The almond tree bears its blossoms in the midst of winter, on a naked, leafless stem, and these blossoms (reddish or flesh-coloured in the beginning) seem at the time of their fall exactly like white snow-flakes. In this way the almond blossom is a very fitting symbol of old age, with its silvery hair and its wintry, dry, barren, unfruitful condition." In Jer.

1:11 "I see a rod of an almond tree [shaked]...for I will hasten [shaked] my word to perform it" the word is used as an emblem of promptitude. Jacob desired his sons (Gen. 43:11) to take with them into Egypt of the best fruits of the land, almonds, etc., as a present to Joseph, probably because this tree was not a native of Egypt. Aaron's rod yielded almonds (Num. 17:8; Heb. 9:4). Moses was directed to make certain parts of the candlestick for the ark of carved work "like unto almonds" (Ex. 25:33, 34). The Hebrew word _luz_, translated "hazel" in the Authorized Version (Gen. 30:37), is rendered in the Revised Version "almond." It is probable that _luz_ denotes the wild almond, while _shaked_ denotes the cultivated variety. Easton's 1897 Bible Dictionary Amygdala - Scholarpedia Amygdala Dr. Joseph E.

LeDoux, Center for Neural Science, NYU, New York, NY Figure 1: Location of amygdala in the brain (reproduced from Wikipedia under GFDL). The amygdaloid region of the brain (i.e. the amygdala) is a complex structure involved in a wide range of normal behavioral functions and psychiatric conditions. Not so long ago it was an obscure region of the brain that attracted relatively little scientific interest. Today it is one of the most heavily studied brain areas, and practically a household word. This article will summarize the anatomical organization of the amygdala and its functions. Contents 5 See Also Anatomical organization The existence of the amygdala was first formally recognized in the early 19th century. The name, derived from the Greek, was meant to denote the almond-like shape of this region in the medial temporal lobe. Much debate has since ensued, and continues today, about how the amygdala should be subdivided. Also controversial is how the subdivisions relate to other major regions of the brain.

One long-standing idea is that the amygdala consists of an evolutionarily primitive division associated with the olfactory system (cortical, medial and central nuclei) and an evolutionarily newer division associated with the neocortex (lateral, basal, and accessory basal nuclei). The areas of the older division are sometimes grouped as the cortico-medial region (cortical and medial nuclei) and sometimes as the centro-medial region (the central and medial nuclei). In contrast, the newer structures related to the neocortex are often referred to as the basolateral region. The almond shaped structure that originally defined the amygdala included the basolateral region rather than the whole structure now considered to be the amygdala. In recent years, there have been a number of attempts to reclassify the amygdala and its relation to other areas. For example, Heimer and colleagues have argued for the concept of an extended amygdala. In this view, the central and medial amygdala form continuous structures with the lateral and medial divisions of the bed nucleus of the stria terminalis.

A more radical notion comes from Swanson and Petrovich, who propose that idea that “the amygdala,” whether extended or not, does not exist as a structural unit. Instead, they argue that the amygdala consist of regions that belong to other regions or systems of the brain and that the designation “the amygdala” is not necessary. For example, in this scheme, the lateral and basal amygdala are viewed as nuclear extensions of the neocortex (rather than amygdala regions related to the neocortex), the central and medial amygdala are said to be ventral extensions of the striatum , and the cortical nucleus is associated with the olfactory system. While this scheme has some merit, the present review focuses on the organization and function of nuclei and subnuclei that, while traditionally said to be part of the amygdala, nevertheless perform their functions regardless of whether the amygdala itself exists, or whether it is extended. It is easy to be confused by the terminology used to describe the amygdala nuclei, as different sets of terms are used. This problem is especially acute with regards to the basolateral region of the amygdala.

One popular scheme refers to the basolateral region as consisting of the lateral, basal and accessory basal nuclei. Another scheme uses the terms basolateral and basomedial nuclei to refer to the regions named as the basal and accessory basal nuclei in the first scheme. Particularly confusing is the use of the term basolateral to refer to both a specific nucleus (the basal or basolateral nucleus) and to the larger region that includes the lateral, basal and accessory basal nuclei (the basolateral complex). Another confusing point involves the cortical nucleus. Being a cortical structure, albeit a primitive olfactory one, it is sometimes associated with the basolateral region, but is also often grouped with the medial nucleus to form the cortico-medial amygdala. The major nuclei of the amygdala are shown in sections from the rat brain in Figure 2 . Figure 2: Some areas of the amygdala, as shown in the rat brain. The same nuclei are present in primates, including humans. Different staining methods show amygdala nuclei from different perspectives. Left panel: Nissl cell body stain. Middle panel: acetylcholinesterase stain. Right panel, silver fiber stain.

Abbreviations of amygdala areas: AB, accessory basal; B, basal nucleus; Ce, central nucleus; itc, intercalated cells; La: lateral nucleus; M, medial nucleus; CO, cortical nucleus. Non-amygdala areas: AST, amygdalo-striatal transition area; CPu, caudate putamen; CTX, cortex. Figure 3: Some of the major input and output connections of the amygdala. Sensory abbreviations: aud, auditory; vis, visual; somato, somatosensory; gust, gustatory (taste); olf, olfactory. Modulatory arousal systems abbreviations: NE, norepinephrine, DA, dopamine, ACh, acetylcholine; 5HT, serotonin). The amygdala has a wide range of connections with other brain regions, allowing it to participate in a wide variety of behavioral functions. Some of the major connections are shown above in Figure 3 . Different nuclei of the amygdala have unique connections (Figure 4 , Figure 5 , and Figure 6 ), which is why each nucleus makes unique contributions to functions. A thorough discussion of all the connections is beyond the present scope.

Therefore, a few key examples will be given. The lateral amygdala is a major site receiving inputs from visual, auditory, somatosensory (including pain) systems, the medial nucleus of the amygdala is strongly connected with the olfactory system, and the central nucleus connects with brainstem areas that control the expression of innate behaviors and associated physiological responses. In many instances, the subnuclei of a given nucleus also have distinct connections. The lateral nucleus, for example, includes dorsal, medial, and ventrolateral subnuclei, while the central nucleus contains lateral, capsular, and medial subnuclei. The dorsal subnucleus of the lateral nucleus receives much of the direct sensory flow to the amygdala, while the medial division of the central nucleus is the part that connects with response control regions. Figure 4: Inputs to some specific amygdala nuclei. Abbreviations of amygdala areas: basal; B, basal nucleus; Ce, central nucleus; itc, intercalated cells; LA: lateral nucleus; M, medial nucleus. Sensory abbreviations: aud, auditory; vis, visual; somato, somatosensory; gust, gustatory (taste).

Figure 5: Outputs of some specific amygdala nuclei. Abbreviations of amygdala areas: basal; B, basal nucleus; Ce, central nucleus; itc, intercalated cells; LA: lateral nucleus. Modulatory arousal systems abbreviations: NE, norepinephrine, DA, dopamine, ACh, acetylcholine; 5HT, serotonin). Other abbreviations: parasym ns, parasympathetic nervous system ; symp ns, sympathetic nervous system. Figure 6: Flow of sensory information to the lateral amygdala and through amygdala circuits to output systems. Abbreviations of amygdala areas: basal; B, basal nucleus; Ce, central nucleus; itc, intercalated cells; LA: lateral nucleus; M, medial nucleus. Modulatory arousal systems abbreviations: NE, norepinephrine, DA, dopamine, ACh, acetylcholine; 5HT, serotonin). Most of the inputs to the amygdala involve excitatory pathways that use glutamate as a transmitter. These inputs form synaptic connections on the dendrites of excitatory principal neurons that transit signals to other regions or subregions of the amygdala or to extrinsic regions.

Principal neurons are thus also called projection neurons since the project out. However, axons of principal neurons also give rise to local connections to inhibitory interneurons that then provide feedback inhibition to the principal neurons. In addition to terminating on projection neurons, some of the excitatory inputs to the amygdala terminate on local inhibitory interneurons that in turn connect with principal neurons, giving rise to feedforward inhibition. The scheme of connections just described applies to the neurons of the basolateral complex more so than to neurons within the centro-medial group. For example, while the projection neurons of the basolateral group are excitatory, the projection neurons in the central nucleus tend to be inhibitory in nature. Thus, excitation of neurons in the central nucleus leads to inhibition of target neurons, while inhibition of these projection neurons gives rise to increased output of the target neurons. Whether central amygdala cells are activated by excitatory projection neurons or by way of connections from projection neurons to local interneurons thus influences the ultimate output state of the central amygdala. These connections are consistent with the notion described above that the basolateral group is closely associated with the cerebral cortex and the cortico-medial group with the basal ganglia.

The flow of information through amygdala circuits is modulated by a variety of neurotransmitter systems. Thus, norepinephrine, dopamine, serotonin, and acetylcholine released in the amygdala influences how excitatory and inhibitory neurons interact. Receptors for these various neuromodulators are differentially distributed in the various amygdala nuclei. Also differentially distributed are receptors for various hormones, including glucocorticoid and estrogen. Numerous peptides receptors are also present in the amygdala, including receptors for opioid peptides, oxytocin, vasopressin, corticotropin releasing factor, and neuropeptide Y, to name a few. Function In the late 1930s, researchers observed that damage to the temporal lobe resulted in profound changes in fear reactivity, feeding, and sexual behavior. Around mid century, it was determined that damage to the amygdala accounted for these changes in emotional processing. Numerous studies subsequently attempted to understand the role of the amygdala in emotional functions, especially fear.

The result was a large and confusing body of knowledge about the functions of the amygdala because much of the research ignored the nuclear and subnuclear organization of the amygdala, which was not fully appreciated, and partly because the functions measured by behavioral tasks were not well understood. Fear conditioning The early studies of fear used avoidance conditioning tasks. These measure fear in terms of how well an animal leans to avoid shock. However, avoidance is a two stage process in which Pavlovian conditioning establishes fear responses to stimuli that predict the occurrence of the shock, and then new behaviors that allow escape from or avoidance of the shock, and thus that reduce the fear elicited by the stimuli, are learned. In the 1980s, researchers began to use tasks that isolated the Pavlovian from the instrumental components of the task to study the brain mechanisms of fear. This strategy allowed a focus on the fear reaction conditioned by the shock rather than on behaviors that avoid the shock. Figure 7: Auditory fear conditioning paradigm. Studies using this paradigm have helped elaborate the functional role of amygdala nuclei. Rats are habituated to the chamber on day 1 (no stimulation).

On day 2, the rat receives a small number of training trials (typically 1-5) in which a tone CS is paired with a footshock US. Controls receive unpaired presentations of the CS and US. On day 3, the CS is presented in a novel chamber with a unique odor (peppermint) and fear responses (freezing) to the CS assessed. Animals receiving pairings on day 2 show high levels of freezing but animals receiving unpaired training show little freezing. Figure 8: Auditory fear conditioning pathways. The auditory conditioned stimulus (CS) and somatosensory (pain) unconditioned stimulus (US) converge in the lateral amygdala (LA). The LA receives inputs from each system via both thalamic and cortical inputs. CS-US convergence induces synaptic plasticity in LA such that after conditioning the CS flows through the LA to activate the central amygdala (CE) via intra-amygdala connections. CE in turn controls the expression of behavioral (freezing), autonomic and endocrine responses that are components of the fear reaction.

Other abbreviations: B, basal amygdala; CG, central gray; LH, lateral hypothalamus ; ITC, intercalated cells of the amygdala; PVN, paraventricular nucleus of the hypothalamus. In Pavlovian fear conditioning a neutral conditioned stimulus (CS) that is paired with a painful shock unconditioned stimulus (US) comes to elicit fear responses such as freezing behavior and related physiological changes (Figure 7 ). Studies in rodents have mapped the inputs to and outputs of amygdala nuclei and subnuclei that mediate fear conditioning. In particular, it is widely accepted that convergence of the CS and US leads to synaptic plasticity in the dorsal subregion of the lateral amygdala. When the CS then occurs alone later, it flows through these potentiated synapses to the other amygdala targets and ultimately to the medial part of the central nucleus, outputs of which control conditioned fear responses (Figure 8 ). Much has been learned about the cellular and molecular mechanisms within lateral amygdala cells that underlie the plastic changes.

In brief, convergence of the strong US inputs to cells that also receive CS inputs results in an elevation of intracellular calcium, and event that triggers a host of molecular responses leading to protein synthesis (Figure 9 ). The proteins then help strengthen stabilize the CS input synapses, allowing them to respond more strongly to the CS after conditioning. As a result, the CS flows through the amygdala circuits to elicit the fear responses controlled by the central nucleus. Amygdala areas, together with the prefrontal cortex and hippocampus , is involved in the reduction of learned fear through extinction and cognitive regulatory processes. Figure 9: Intracellular signal transduction pathways underlying auditory fear conditioning in LA cells. Reward processing Although fear is the emotion best understood in terms of brain mechanisms, the amygdala has also been implicated in a variety of other emotional functions. A relatively large body of research has focused on the role of the amygdala in processing of rewards and the use of rewards to motivate and reinforce behavior. As with aversive conditioning, the lateral, basal, and central amygdala have been implicated in different aspects of reward learning and motivation , though the involvement of these nuclei differs somewhat from their role in fear.

The amygdala has also been implicated in emotional states associated with aggressive, maternal, sexual, and ingestive (eating and drinking) behaviors. Less is known about the detailed circuitry involved in these emotional states than is known about fear. Other Functions Because the amygdala learns and stores information about emotional events, it is said to participate in emotional memory . Emotional memory is viewed as an implicit or unconscious form of memory and contrasts with explicit or declarative memory mediated by the hippocampus. In addition to its role in emotion and unconscious emotional memory, the amygdala is also involved in the regulation or modulation of a variety of cognitive functions, such as attention , perception, and explicit memory. It is generally thought that these cognitive functions are modulated by the amygdala's processing of the emotional significance of external stimuli. Outputs of the amygdala then lead to the release of hormones and/or neuromodulators in the brain that then alter cognitive processing in cortical areas. For example, via amygdala outputs that ultimately affect the hippocampus, explicit memories about emotional situations are enhanced. For example, glucocorticoid hormone released into the blood stream via amygdala activity travels to the brain and then binds to neurons in the basal amygdala.

The latter then connects to the hippocampus to enhance explicit memory. There is also evidence that the amygdala can, through direct neural connections, modulate the function of cortical areas. Over the past decade, interest in the human amygdala has grown considerably, spurred on by the progress in animal studies and by the development of functional imaging techniques. As in the animal brain, damage to the human amygdala interferes with fear conditioning and functional activity changes in the human amygdala in response to fear conditioning. Further, exposure to emotional faces potently activates the human amygdala. Both conditioned stimuli and emotional faces produce strong amygdala activation when presented unconsciously, emphasizing the importance of the amygdala as an implicit information processor and its role in unconscious memory. Studies of humans and non-human primates also implicate the amygdala in social behavior. Findings regarding the human amygdala are mainly at the level of the whole region rather than nuclei. Structural and/or functional changes in the amygdala are associated with a wide variety of psychiatric conditions in humans. Included are various anxiety disorders (PTSD, phobia, and panic), depression, schizophrenia , and autism, to name a few.

This does not mean that amygdala causes these disorders. It simply means that in people who have these disorders alterations occur in the amygdala. Because each of these disorders involves fear and anxiety to some extent, the involvement of the amygdala in some of these disorders may be related to the increased anxiety in these patients. Conclusion The rise in popularity of the amygdala as a research topic should not overshadow the fact that much remains to be learned. Especially important for the future will be studies that attempt to understand whether the importance of the amygdala in fear reflects the importance of fear to the amygdala or whether fear is just the function that has been studied most. References Aggleton J, ed (2000) The Amygdala: A Functional Analysis, 2nd Edition. Oxford: Oxford University Press. Amaral DG (2003) The amygdala, social behavior, and danger detection. Ann NY Acad Sci 1000:337-47. Balleine BW, Killcross S (2006) Parallel incentive processing: an integrated view of amygdala function. Trends Neurosci 25: 272-279.

Cardinal RN, Parkinson JA, Hall J, Everitt BJ (2002) Emotion and motivation: the role of the amygdala, ventral striatum, and prefrontal cortex. Neurosci Biobehav Rev 26: 321-352. Davis M (2006) Neural systems involved in fear and anxiety measured with fear-potentiated startle. Am Psychol. 61:741-56. Davis M, Walker DL, Myers, KM (2003) Role of the amygdala in fear extinction measured with potentiated startle. NeuroRx 3: 82-96. Dolan RJ (2007) The human amygdala and orbital prefrontal cortex in behavioural regulation. Philos Trans R Soc Lond B Biol Sci. 362(1481):787-99. Everitt BJ, Cardinal RN, Parkinson JA and Robbins TW (2003) Appetitive behavior: impact of amygdala-dependent aspects of emotional learning. Ann NY Acad Sci 985: 233-250.

Fanselow MS, Gale GD (2003) The amygdala, fear, and memory. Ann NY Acad Sci. 985:125-34. Heimer L (2003) A new anatomical framework for neuropsychiatric disorders and drug abuse. Am J Psychiatry 160: 1726-1739. Holland P and Gallagher M (2004) Amygdala-frontal interactions and reward expectancy. Curr Opin Neurobiol 14: 148-155. LeDoux JE (1996) The Emotional Brain. New York: Simon and Schuster. Maren, S (2005) Synaptic mechanisms of associative memory in the amygdala. Neuron 47: 783-786. McDonald A (1998) Cortical pathways to the mammalian amygdala. Prog Neurobiol 55: 257-332. McGaugh JL (2003) Memory and Emotion: The making of lasting memories. London: The Orion Publishing Group.

Paré D, Quirk, GJ, LeDoux JE (2003) New vistas on amygdala networks in conditioned fear. J Neurophysiol 92: 1-9. Phelps EA, LeDoux JE (2005) Contributions of the amygdala to emotion processing: from animal models to human behavior. Neuron 48:175-187. Pitkänen A, Savander V, LeDoux JE (1997) Organization of intra-amygdaloid circuitries in the rat: an emerging framework for understanding functions of the amygdala. Trends Neurosci 20:517-523. Quirk GJ, Mueller D (2008) Neural mechanisms of extinction learning and retrieval. Neuropsychopharmacology 33: 56-72. Rauch SL, Shin LM, Wright CI (2003) Neuroimaging studies of amygdala function in anxiety disorders. Ann NY Acad Sci 985:389-410.

Rodrigues SM, Schafe GE, and LeDoux JE (2004) Molecular mechanisms underlying emotional learning and memory in the lateral amygdala. Neuron 44: 75-91. Rolls, ET (1999) The Brain and Emotion. Oxford, Oxford University Press. Shinnick-Gallagher P, Pitkanen A, Shekhar, A, and Cahill L, eds (2003) The Amygdala in Brain Function: Basic and Clinical Approaches. New York, New York Academy of Sciences. Swanson LW, Petrovich GD (1998) What is the amygdala? Trends Neurosci 21:323-331. Internal references amygdala | anatomy | Britannica.com Amygdala Alternative Titles: amygdaloid body, archistriatum Related Topics forebrain Amygdala, region of the brain primarily associated with emotional processes. The name amygdala is derived from the Greek word amygdale, meaning “almond,” owing to the structure’s almondlike shape.

The amygdala is located in the medial temporal lobe, just anterior to (in front of) the hippocampus . Similar to the hippocampus, the amygdala is a paired structure, with one located in each hemisphere of the brain. The amygdala is part of the limbic system, a neural network that mediates many aspects of emotion and memory . Although historically the amygdala was considered to be involved primarily in fear and other emotions related to aversive (unpleasant) stimuli, it is now known to be involved in positive emotions elicited by appetitive (rewarding) stimuli. Anatomy of the amygdala The amygdala comprises a group of nuclei, or clusters of neurons . The basolateral complex, the largest of the clusters and located roughly in the lateral and middle parts of the amygdala, includes the lateral, basal, and accessory-basal nuclei. The lateral nucleus is the major recipient of input from sensory cortices (cortical brain regions that represent information about sensory stimuli) of all modalities (e.g., vision, hearing).

In addition, it has been established that in rodents information about auditory stimuli arrives in the amygdala directly from a subcortical (beneath the cortex) area of the brain known as the medial geniculate nucleus, which is located in the thalamus. The cortical and medial nuclei of the amygdala form the so-called cortico-medial group. Olfactory (smell) information flows directly into the cortico-medial amygdala from the olfactory bulb and pyriform cortex, both of which function in the sense of smell . The intercalated masses are a ribbon of inhibitory neurons that gate information flow from the basolateral complex to the central nucleus of the amygdala. In addition to sensory input, the amygdala receives input from a number of cortical and subcortical brain systems. Most prominently, the amygdala receives dense input from the prefrontal cortex, especially from the anterior cingulate and orbitofrontal cortices. The amygdala also receives prominent input from the insula and from the hippocampus and rhinal (olfactory) cortices. Subcortical information flows to the amygdala from numerous nuclei, including every neuromodulatory system.

Britannica Stories EU Considers Rules For Robots Output from the amygdala can be directed to both subcortical and cortical brain structures. The central nucleus is directed to numerous subcortical structures known to mediate different autonomic, physiologic, and behavioral expressions of emotional state. The basal and accessory-basal nuclei are the major outputs of the amygdala directed to the cerebral cortex. Those anatomical projections may underlie the role of the amygdala in modulating cognitive processes such as decision making , attention, and memory. Function of the amygdala The amygdala plays a prominent role in mediating many aspects of emotional learning and behaviour. There exist a vast array of human emotions, ranging from joy to sadness, disgust to excitement, and regret to satisfaction. Most emotions possess a valence (positive or negative) and an intensity (low to high) that reflects emotional arousal. Studies of the neural basis of emotion in animal models, including those focusing on the amygdala, typically have utilized physiological (e.g., autonomic) or behavioral (e.g., approach or defense) measures that likely reflect the valence and intensity of an emotional experience.

In the early part of the 20th century, psychologist Heinrich Klüver and neurosurgeon Paul C. Bucy studied monkeys with lesions of the temporal lobe that included the amygdala and observed changes in emotional, feeding, and sexual behaviour. Subsequent studies established that the amygdala was a critical structure mediating those effects. Role in innate and learned emotional behaviour Pheromones and innately appetitive and aversive stimuli, including certain odours, tastes, or sexual imagery, can produce physiological and behavioral expressions of emotional state. For olfactory stimuli, the cortico-medial amygdala is known to mediate innate emotional behaviour. For other innately reinforcing stimuli, including some drugs of abuse , circuitry within the basolateral complex likely also contributes to emotional responses. Science Quiz Emotional learning most commonly has been studied in both animal models and humans, using Pavlovian conditioning , in which an otherwise neutrally conditioned stimulus is paired with an innately aversive unconditioned stimulus. This type of paradigm , often referred to as fear conditioning, can result in robust learning, owing to the convergence of sensory information about the conditioned stimulus and the unconditioned stimulus.

Neuromodulatory input may also contribute to this learning. As an animal learns, the responses of amygdala neurons to conditioned stimuli change, reflecting the learning process. Furthermore, the activation of neurons in the basolateral amygdala can induce learning, suggesting that those neurons play a causal role in emotional learning. After learning, input from the basolateral complex to the central nucleus of the amygdala leads to the orchestration of a range of physiological and behavioral responses that are correlated with emotional states. Measures of fear conditioning include the cessation of movement (“freezing”), a defensive behaviour, and increased skin conductance responses or increased blood pressure (autonomic measures that reflect arousal level). Lesions of the amygdala impair the acquisition and expression of this learning. Listen to a case study about a woman who lost the ability to learn from fear. © American Chemical Society (A Britannica Publishing Partner) Connect with Britannica Facebook Twitter YouTube Instagram Pinterest Although the study of the amygdala has been most extensively pursued by means of aversive stimuli, there is substantial evidence that the amygdala is also involved in the processing of rewarding stimuli and in appetitive learning.

Within the amygdala neural responses to conditioned stimuli change during appetitive learning, and many amygdala neurons respond to different rewarding stimuli. The activation of amygdala neurons that respond to a rewarding stimulus can induce both Pavlovian and instrumental learning (learning in which behaviour is influenced by consequences). A pathway from the amygdala to the ventral striatum, which has been implicated in reward processing in addiction, mediates learned approach behaviours (movements toward objects or other individuals). However, amygdalar lesions often do not impair appetitive learning, indicating that such learning is likely also supported by parallel neural pathways that do not involve the amygdala. Regulation of emotion Emotional responses to sensory stimuli not only arise through innate mechanisms and through learning but also can be altered by extinction and cognitive control mechanisms. Both extinction and cognitive control involve interactions between the prefrontal cortex and the amygdala. Extinction, which itself is a learning process, is induced by the repeated presentation of a conditioned stimulus in the absence of a previously associated unconditioned stimulus, resulting in the elimination of a previously elicited response.

Projections from the prefrontal cortex to the amygdala mediate extinction, with complex circuitry involving the central nucleus, the basolateral complex, and the intercalated masses playing a role in the modification of responses to previously conditioned stimuli. Britannica Lists & Quizzes nut - Dictionary Definition : Vocabulary.com Random Word nut A nut is a kind of fruit made of a large, edible seed with a very hard shell around it. The nuts that squirrels typically gather (sometimes storing them temporarily in their cheek pouches) are acorns. It might seem strange that a nut is a fruit, since until they've been cracked open, most nuts are as hard and inedible as rocks. Think of the meat of a walnut or almond that hides inside — this is the edible seed within the fruit. If someone calls you a nut, or describes you as nuts or nutty, they think you're crazy or wacky, and when you refer to "a tough nut to crack," you're talking about a tricky problem. Amygdala (Definition, Function, Location) Updated April 15, 2016.

Amygdala The amygdala is an almond shaped mass of nuclei (mass of cells) located deep within the temporal lobes of the brain . There are two amygdalae, one situated in each brain hemisphere. The amygdala is a limbic system structure that is involved in many of our emotions and motivations, particularly those that are related to survival. It is involved in the processing of emotions such as fear, anger, and pleasure. The amygdala is also responsible for determining what memories are stored and where the memories are stored in the brain. It is thought that this determination is based on how huge an emotional response an event evokes. Amygdala and Fear The amygdala is involved in autonomic responses associated with fear and hormonal secretions. Scientific studies of the amygdala have led to the discovery of the location of neurons in the amygdala that are responsible for fear conditioning. Fear conditioning is an associative learning process by which we learn through repeated experiences to fear something. continue reading below our video 10 Facts About the Titanic That You Don't Know Our experiences can cause brain circuits to change and form new memories. For example, when we hear an unpleasant sound , the amygdala heightens our perception of the sound.

This heightened perception is deemed distressing and memories are formed associating the sound with unpleasantness. If the noise startles us, we have an automatic flight or fight response. This response involves the activation of the sympathetic division of the peripheral nervous system . Activation of the nerves of the sympathetic division results in accelerated heart rate, dilated pupils, increase in metabolic rate, and increase in blood flow to the muscles . This activity is coordinated by the amygdala and allows us to respond appropriately to danger. Function The amygdala is involved in several functions of the body including: Arousal Autonomic Responses Associated with Fear Emotional Responses Memory Sensory Information The amygdala receives sensory information from the thalamus and from the cerebral cortex . The thalamus is also a limbic system structure and it connects areas of the cerebral cortex that are involved in sensory perception and movement with other parts of the brain and spinal cord that also have a role in sensation and movement. The cerebral cortex processes sensory information obtained from vision, hearing, and other senses and is involved in decision-making, problem solving, and planning. Location Directionally , the amygdala is located deep within the temporal lobes , medial to the hypothalamus and adjacent to the hippocampus .

Amygdala Disorders Hyperactivity of the amygdala or having one amygdala that is smaller than the other has been associated with fear and anxiety disorders. Fear is an emotional and physical response to danger. Anxiety is a psychological response to something that is perceived as dangerous. Anxiety can lead to panic attacks that occur when the amygdala sends signals that a person is in danger, even when there is no real threat. Anxiety disorders that are associated with the amygdala include Obsessive Compulsive Disorder (OCD), Post-Traumatic Stress Disorder (PTSD) , Borderline Personality Disorder (BPD), and social anxiety disorder. More Information

Question: Amygdaloid refers to the shape of what nut?
Answer: Almond