The Amygdala, Social Behavior, and Danger Detection

“Further, it is consistent with the results of the primate mentioned studies above suggesting a role for the amygdala in social emotions (Amaral, 2003).”

“nal in social interaction (Amaral, 2003), both conscious and im-”

“…survival functions such as defense (e.g., LeDoux, 1996, 2012; Phelps and LeDoux, 2005; Motta et al., 2009; Choi et al., 2005; Kalin et al., 2004; Amaral, 2003; Antoniadis et al., 2007), reproduction (e.g., Pfaff, 1999; Oomura et al., 1988; Blaustein, 2008), thermoregulation (Nakamura and…”

“A vast area of research in animal, human lesion, and neuroimaging studies points to the critical role of these brain areas in signaling and modulating fear responses (Adolphs et al., 2005; Amaral, 2003).”

“The amygdala is another candidate region that may be affected in ASD because of its role in modulating fear and social behavior 202,207,208 .”

“The amygdala seems to be particularly involved in the assignment of signal relevance 17,75,91–93 and, as a consequence, in the modulation of brain structures that control behaviour.”

“Amygdala lesions in monkeys confirm that this region is critical in acquisition and appropriate display of fear in social and novel situation”

“Amaral (2003) suggested that the amygdala also plays a major role in surveying and evaluating the environment for danger signals.”

“The primary hypothesis emerging from neuroscience suggests that early developmental disruption of amygdala-PFC circuitry mediates the emergence of attention biases toward threats and subsequent anxiety disorders.(10) If so, then attention to threats should potentiate fear circuit activity differently in youths with an…”

“hippocampus in emotional regulation of activity and social relating, and the relevance of this to child psychopathology is becoming clearer (see Allman et al., 2001; Amaral, 2003).”

“Itwas shown that early developmental disruption of the amygdala-prefrontal circuit indicates an attentional bias toward threats and leads to the development of pathological anxiety (Amaral, 2003; McClure et al., 2007).”

“For example, studies of nonhuman primates show that the developmental timing of amygdala damage profoundly influences social-threatperception.(9,10) These findings raise key questions about the relations between the human amygdala and vPFC function during adolescence when many social-cognitive processes are forming.”

“…Downloaded from http://www.mitpressjournals.org/doi/pdfplus/10.1162/jocn.2008.20114 by guest on 22 May 2021 Studies in nonhuman primates suggest that amygdala lesions produce different effects on social–emotional outcomes as a function of ontogeny (Amaral, 2002, 2003; Prather et al., 2001).”

“With its intricate connections, the amygdala is perfectly situated to code the oscillating value of external threat and for surveying the sensory landscape for potential danger (30).”

“For example, amygdala lesions in adult non-human primates produce broad reductions in fear, whereas the same lesions in childhood produce increases in social fear but reductions in other forms of fear (Amaral, 2003; Bauman, Lavenex et al., 2004).”

“However, amygdala responses in human imaging studies may be linked more tightly to short-term predictive cues than to the core experience of threat or anxiety per se (Amaral, 2003; Anderson et al., 2003; Anderson andPhelps, 2002; Ewbank et al., 2009; Phan et al., 2003; Wager et al., 2008b; Whalen et al., 1998).”

“More recent work has shown that some of the earlier reports with respect to the role in social cognition of the amygdala (Bachevalier, 1994; Kling & Brothers, 1992; Rosvold et al., 1954) were methodologically flawed (see Amaral, 2003).”

“Damage to the primate amygdala during adulthood has inconsistent effects on social interactions but, if occurring during infant development, leads to increased social fear within novel environments.(51,52) Amygdala disturbances early in development, therefore, disrupt the appropriate assignment of emotional significan…”

“, 2008) and corroborates the role played by the amygdala in detecting the occurrence of aversive sensory information (Amaral, 2003; LeDoux, 1995).”

“In this study, we examined the influence of the gut microbiota on expression levels of the common BDNF transcript and BDNF exon-containing transcripts (I IX) in the amygdala, a brain region readily activated in the three-chambered approach paradigm (26) and a central hub in the social brain network (27, 28).”

“The amygdala is hypothesized to play a critical role in a network of brain structures mediating fear responses and triggering threat-related behaviors (Amaral, 2003 ; Blanchard & Blanchard, 1972 ; LeDoux, 2000 ) via its connections with other structures such as the medial prefrontal cortex and the hypothalamus (Ongur…”

“…the amygdala subserves the representation of salience for emotional stimuli, be they either positively or negatively valenced (Adolphs et al., 2005; Amaral, 2003; Anderson, 2005, 2007; Barrett & Niedenthal, 2004; Davis & Whalen, 2001; Kim, Somerville, Johnstone, Alexander, & Whalen, 2003;…”

“Relevant for the present context, via the thalamus the amygdala receives input not only from the visual modality but from all senses (Nishijo et al., 1988; Amaral et al., 1992; Amaral, 2003).”

“But a direct relationship between amygdaloid lesions and reduced fear need not always be the case as the amygdala has been implicated in other functions as well, such as memory (Amaral, 2003; McGaugh et al., 1996) and olfaction (Buck, 1996).”

“Neurons in BLA appear to categorize social events as similar as long as there is a live agent involved (Self, Other, or Both), and do so only during active decision-making, with all its attendant motivational, emotional, and attentional components (17, 21, 24, 56, 57).”

“Several human neuroimaging studies support the idea that amygdala activation is related to the salience or potential information value of visual stimuli (Amaral, 2003; Liberzon, et al., 2003; Whalen et al., 2004), and amygdala engagement has been associated with enhanced memory (e.”

“Such a positive bias effect has also been observed in monkeys after amygdala damage [Amaral, 2003].”

“For example, rhesus monkeys sustaining bilateral amygdaloid lesions do not react appropriately to potentially dangerous social situations (Amaral, 2003).”

“The amygdala is a brain structure essential to the perception of fear (Amaral, 2003; LeDoux, 2003), and activation in the amygdala is reliably produced by presentation of biologically relevant sensory stimuli, and stimuli that predict threat (Whalen, 1998).”

“In primates, a clear role for the amygdala in social, anxious, and depressive behaviors has been established (Brothers, 1990; Drevets, 1999; Baron-Cohen et al., 2000; Emery et al., 2001; Drevets et al., 2002; Amaral, 2003; Bauman et al., 2004; Etkin et al., 2004; Lorberbaum et al., 2004).”

“Human and comparative studies have identified the amygdala as a central component in processing threat-related stimuli (Amaral, 2003; Davis and Whalen, 2001; LeDoux, 2000), playing a predominant role in fear conditioning (LaBar et al., 1995) and processing facial and vocal signals of fear (Adolphs…”

“In considering what neural circuits might mediate associations between the gut microbiota and these outcomes, the amygdala has attracted considerable research attention due to its central role in fear (Amaral 2003; Canteras et al. 2010), stress (Ressler 2010), emotional regulation (Banks et al.”

“therefore argued to be involved in the automatic assessment of threat,(16) and acquisition and extinction of conditioned fear.(6,17,18) Furthermore, the BLA can through mutual connections with the PFC, especially the orbitofrontal cortex (OFC),”

“Consistent with the assumption that amygdala activation represents a danger signal in social interaction (Amaral, 2003), both conscious and implicit distrust of faces predicts amygdala activation (Winston et al.”

“…the amygdala mediates adaptive and maladaptive fear and anxiety responses (Blanchard and Blanchard, 1972;LeDoux, 2000; Davis and Whalen, 2001; Amaral, 2003; Kalin et al., 2004), it is of particular importance that ferret exposure increased c-fos expression within various nuclei of the…”

“A: axial, sagittal, and coronal views of significant response differences between CCHS and control groups in a cluster extending from the right putamen (1) to the claustrum (2) and the ventral insula (3).”

“Pain and fear can signal immediate challenge to survival and warn the organism to prepare for the worst (Amaral, 2006; Rogan, Leon, Perez, & Kandel, 2005).”

“…and memory, it is also a well-established key emotional brain centre for evaluating and responding to social stimuli in humans and other mammals (Allsop et al., 2014; Amaral, 2003; Kliemann et al., 2012; Noonan et al., 2014; Phelps and LeDoux, 2005; Sabatini et al., 2007; Sallet et al., 2011).”

“Many researchers have concluded that anxiety disorders must be linked with changes in the hippocampus and/or amygdala (Amaral, 2003; Hariri et al., 2002; Ledoux & Muller, 1997; Quirk & Gehlert, 2003; Walker, Toufexis, & Davis, 2003), and it is possible that these changes occur because of some interaction between the G…”

“…that panic attacks have a non-associative mode of acquisition, and are most probably triggered by impaired orbitofrontal or mediofrontal governance over innate hardwired danger-detection circuits linking the locus ceruleus to the amygdala (Kent et al., 2005; Gorman, 2004; Amaral, 2003).”

“A role for the amygdala in this process is further supported by data in non-human primates showing impaired responses to fearful stimuli following infant amygdala lesions (Amaral, 2003; Bauman et al., 2006; Marquez et al., 2013).”

“The amygdala has been implicated in threat processing (Amaral, 2003; LeDoux, 1998) and in assigning salience to stimuli more broadly (Liberzon et al.”

“…affect (e.g. Adolphs et al., 1994; Barrett et al., 2007; Lanteaume et al., 2007; LeDoux et al., 1988; Sharot et al., 2007), social behavior (e.g. Amaral, 2003; Machado et al., 2008; Rosvold et al., 1954), attention (e.g. Pessoa et al., 2002a, 2002b; Ursin and Kaada, 1960), perception (e.g.…”

“, 1992], and the amygdala in fear conditioning [Ohman and Mineka, 2001], motivation [Rolls, 1992], social behavior [Adolphs 2010; Amaral, 2003; Meunier and Bechevalier, 2002], and in a wide variety of tasks with an emotional component [Aggleton, 1992; Aggleton, 2000; Gallagher and Chiba, 1996].”

“The amygdala functions as a danger and salience detector and, in turn, plays a key role in social and emotional regulation (Amaral, 2003; Adolphs, 2010).”

“…of the cingulate cortex with other limbic sites, including the insula and amygdala, structures which also respond to loaded breathing tasks inducing dyspnea (Banzett et al., 2000; Evans et al., 2002), and, especially in the case of the amygdala, mediate negative emotions (Amaral, 2003).”

“This structure is established as having a clear role in social, anxious, and depressive behaviors in the nonhuman primate (Baron-Cohen et al., 2000; Emery et al., 2001; Drevets et al., 2002; Amaral, 2003; Bauman et al., 2004; Etkin et al., 2004; Lorberbaum et al., 2004).”

“Amygdala lesions have been shown to specifically increase social interactions with nonfamiliar animals (shown in primates by Amaral (2003)).”

“This is consistent with the nonhuman primate literature, where precocious activation of the amygdala puts a brake on social behavior (36, 52, 53).”

“SD patients may be less aware of and less sensitive to negative affect in others because of comprehension difficulties and degeneration of brain structures such as the amygdala, which are important for social behaviors and threat-perception (Aggleton and Passingham, 1981; Amaral, 2003).”

“…temporal lobe of the brain (Saygin et al. 2011) and is known to have a primary role in processing memory, emotional learning (Davis 1994), decision making (Cohen et al. 2008), social interaction, awareness and fear (Amaral 2003), aggression and sexual behavior (Stoddard-Apter and MacDonnell 1980).”

“…affective processing, it also performs the more basic function of maintaining vigilance (Whalen, 2007) by directing an organism to learn more about a stimulus so as to better determine its predictive value for well-being or survival (Barrett et al., 2007; Rolls, 2005; Whalen, 1998; Amaral, 2003).”

“This inability is thought to underlie generalized anxiety disorder (GAD) (Mennin et al. 2005), characterized by inappropriately high stress responses relative to a situation or event ( Amaral 2003 ).”

“The first consisted of resting baseline measures of CMRgl assessed with the F-FDG (F-labeled 2-fluoro2-deoxy-D-glucose) method and published in Gur et al. (1995). That sample included 60 healthy volunteers (37 men, 23 women), age ± SD 27.”

“The importance of amygdala in generating emotional responses was shown in numerous studies (Adolphs et al., 2002; Amaral, 2003; Davis, 1992a; Davis and Myers, 2002; Hilton SM, 1963; Kaada, 1972; Kapp BS, 1992; LeDoux, 1992; Sanders and Shekhar, 1995).”

“In addition, most brain lesions occur in late adolescence or adulthood, precluding an understanding of the developmental consequences of lesions to structures like the amygdala, damage to which may result in distinct behavioral outcomes in adulthood relative to infancy (Amaral, 2003).”

“The amygdala is particularly sensitive to threatening social signals (Zald, 2003), and is critically involved in the perception of potential of danger (Amaral, 2003).”

“Complicated bidirectional projections also exist between higher sensory areas and single sensory areas and the amygdala (Amaral, 2003).”

“Numerous studies suggest that the amygdala mediates both conditioned and unconditioned fear responses (Amaral 2003; Blanchard & Blanchard 1972; Kalin et al. 2004; LeDoux 2000) and human functional imaging studies show that some patients with anxiety and depressive disorders have increased amygdala activation (Drevets…”

“Indeed, as one of the most extensively connected subcortical regions of the brain, with links to numerous cortical and subcortical regions (Amaral, 2003; Amaral, Price, Pitkanen, & Carmichael, 1992; LeDoux, 2000), the amygdala has a significant role in all the stages of memory.”

“Amaral (2003) has pointed out that the projections of amygdala to visual cortical areas have a typical pattern of feedback-type projections which appear to modulate information processing by enhancing neural responses (Hupe et al., 2001).”