Journal articles on the topic 'Amygdala'
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1
Staniloiu, Angelica, and Hans J. Markowitsch. "A rapprochement between emotion and cognition: Amygdala, emotion, and self-relevance in episodic-autobiographical memory." Behavioral and Brain Sciences 35, no. 3 (May 23, 2012): 164–66. http://dx.doi.org/10.1017/s0140525x11001543.
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AbstractLindquist et al. remark that not all fear instances lead to heightened amygdalar activity and, instead, point to roles of the amygdala in detecting “motivationally salient “or “emotionally impactful” stimuli. By reviewing research on the amygdala's functions in episodic-autobiographical memory, we further emphasize the involvement of the amygdala in coding the subjective relevance and extracting the biological and social significance of the stimuli.
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Nolan, Mark, Elena Roman, Anurag Nasa, Kirk J. Levins, Erik O’Hanlon, Veronica O’Keane, and Darren Willian Roddy. "Hippocampal and Amygdalar Volume Changes in Major Depressive Disorder: A Targeted Review and Focus on Stress." Chronic Stress 4 (January 2020): 247054702094455. http://dx.doi.org/10.1177/2470547020944553.
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Medial temporal lobe structures have long been implicated in the pathogenesis of major depressive disorder. Although findings of smaller hippocampal and amygdalar volumes are common, inconsistencies remain in the literature. In this targeted review, we examine recent and significant neuroimaging papers examining the volumes of these structures in major depressive disorder. A targeted PubMed/Google Scholar search was undertaken focusing on volumetric neuroimaging studies of the hippocampus and amygdala in major depressive disorder. Where possible, mean volumes and accompanying standard deviations were extracted allowing computation of Cohen’s ds effect sizes. Although not a meta-analysis, this allows a broad comparison of volume changes across studies. Thirty-nine studies in total were assessed. Hippocampal substructures and amygdale substructures were investigated in 11 and 2 studies, respectively. The hippocampus was more consistently smaller than the amygdala across studies, which is reflected in the larger cumulative difference in volume found with the Cohen’s ds calculations. The left and right hippocampi were, respectively, 92% and 91.3% of the volume found in controls, and the left and right amygdalae were, respectively, 94.8% and 92.6% of the volume of controls across all included studies. The role of stress in temporal lobe structure volume reduction in major depressive disorder is discussed.
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Tsai, Sheng-Feng, Hung-Tsung Wu, Pei-Chun Chen, Yun-Wen Chen, Megan Yu, Shun-Fen Tzeng, Pei-Hsuan Wu, Po-See Chen, and Yu-Min Kuo. "Stress Aggravates High-Fat-Diet-Induced Insulin Resistance via a Mechanism That Involves the Amygdala and Is Associated with Changes in Neuroplasticity." Neuroendocrinology 107, no. 2 (2018): 147–57. http://dx.doi.org/10.1159/000491018.
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Background: The notion that exposure to chronic stress predisposes individuals to developing type 2 diabetes (T2D) has gained much attention in recent decades. Long-term stress induces neuroadaptation in the amygdala and increases corticosterone levels. Corticosterone, the major stress hormone in rodents, induces insulin resistance and obesity in mice. However, little is known about whether the stress-induced amygdalar neuroadaptation could promote the risk of T2D. Methods: We used an 11-week high-fat diet (HFD) feeding paradigm to induce insulin dysfunction in mice, followed by implementation of a 10-day social defeat (SD) stress protocol. Results: Mice receiving SD at the beginning of the HFD feeding aggravated HFD-induced insulin resistance and white adipose tissue expansion. HFD mice had higher levels of plasma corticosterone, which was not affected by the SD. The SD stress upregulated the expression of TrkB and synaptotagmin-4 in the amygdala of HFD mice. Bilateral lesions of the central amygdalae before SD stress inhibited the stress-induced aggravating effect without affecting the HFD-induced elevation of plasma corticosterone. Conclusions: Stress aggravates HFD-induced insulin resistance and neuroadaptation in the amygdala. The HFD-induced insulin resistance is amygdala-dependent. Understanding the role of stress-induced amygdalar adaptation in the development of T2D could inform therapies aimed at reducing chronic stressors to decrease the risk for T2D.
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Oshri, Assaf, Joshua C. Gray, Max M. Owens, Sihong Liu, Erinn Bernstein Duprey, Lawrence H. Sweet, and James MacKillop. "Adverse Childhood Experiences and Amygdalar Reduction: High-Resolution Segmentation Reveals Associations With Subnuclei and Psychiatric Outcomes." Child Maltreatment 24, no. 4 (April 28, 2019): 400–410. http://dx.doi.org/10.1177/1077559519839491.
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The aim of the present study was 2-fold: (1) to utilize improved amygdala segmentation and exploratory factor analysis to characterize the latent volumetric structure among amygdala nuclei and (2) to assess the effect of adverse childhood experiences (ACEs) on amygdalar morphometry and current psychiatric symptoms. To investigate these aims, structural (T1) MRI and self-report data were obtained from 119 emerging adults. Regression analysis showed that higher ACE scores were related to reduced volume of the right, but not the left, amygdalar segments. Further, exploratory factor analysis yielded a two-factor structure, basolateral and central-medial nuclei of the right amygdala. Stractual equation modeling analyses revealed that higher ACE scores were significantly related to a reduced volume of the right basolateral and central-medial segments. Furthermore, reduction in the right basolateral amygdala was associated with increased anxiety, depressive symptoms, and alcohol use. This association supports an indirect effect between early adversity and psychiatric problems via reduced right basolateral amygdalar volume. The high-resolution segmentation results reveal a latent structure among amygdalar nuclei, which is consistent with prior work conducted in nonhuman mammals. These findings extend previous reports linking early adversity, right amygdala volume, and psychopathology.
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Tomasino, B., M. Bellani, C. Perlini, G. Rambaldelli, R. Cerini, M. Isola, M. Balestrieri, et al. "Altered microstructure integrity of the amygdala in schizophrenia: a bimodal MRI and DWI study." Psychological Medicine 41, no. 2 (May 12, 2010): 301–11. http://dx.doi.org/10.1017/s0033291710000875.
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BackgroundThe amygdala plays a central role in the fronto-limbic network involved in the processing of emotions. Structural and functional abnormalities of the amygdala have recently been found in schizophrenia, although there are still contradictory results about its reduced or preserved volumes.MethodIn order to address these contradictory findings and to further elucidate the possibly underlying pathophysiological process of the amygdala, we employed structural magnetic resonance imaging (MRI) and diffusion weighted imaging (DWI), exploring amygdalar volume and microstructural changes in 69 patients with schizophrenia and 72 matched healthy subjects, relating these indices to psychopathological measures.ResultsMeasuring water diffusivity, the apparent diffusion coefficients (ADCs) for the right amygdala were found to be significantly greater in patients with schizophrenia compared with healthy controls, with a trend for abnormally reduced volumes. Also, significant correlations between mood symptoms and amygdalar volumes were found in schizophrenia.ConclusionsWe therefore provide evidence that schizophrenia is associated with disrupted tissue organization of the right amygdala, despite partially preserved size, which may ultimately lead to abnormal emotional processing in schizophrenia. This result confirms the major role of the amygdala in the pathophysiology of schizophrenia and is discussed with respect to amygdalar structural and functional abnormalities found in patients suffering from this illness.
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Adolphs, Ralph, and Daniel Tranel. "Impaired Judgments of Sadness But Not Happiness Following Bilateral Amygdala Damage." Journal of Cognitive Neuroscience 16, no. 3 (April 2004): 453–62. http://dx.doi.org/10.1162/089892904322926782.
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Although the amygdala's role in processing facial expressions of fear has been well established, its role in the processing of other emotions is unclear. In particular, evidence for the amygdala's involvement in processing expressions of happiness and sadness remains controversial. To clarify this issue, we constructed a series of morphed stimuli whose emotional expression varied gradually from very faint to more pronounced. Five morphs each of sadness and happiness, as well as neutral faces, were shown to 27 subjects with unilateral amygdala damage and 5 with complete bilateral amygdala damage, whose data were compared to those from 12 braindamaged and 26 normal controls. Subjects were asked to rate the intensity and to label the stimuli. Subjects with unilateral amygdala damage performed very comparably to controls. By contrast, subjects with bilateral amygdala damage showed a specific impairment in rating sad faces, but performed normally in rating happy faces. Furthermore, subjects with right unilateral amygdala damage performed somewhat worse than subjects with left unilateral amygdala damage. The findings suggest that the amygdala's role in processing of emotional facial expressions encompasses multiple negatively valenced emotions, including fear and sadness.
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Knuepfer, M. M., A. Eismann, I. Schutze, H. Stumpf, and G. Stock. "Responses of single neurons in amygdala to interoceptive and exteroceptive stimuli in conscious cats." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 268, no. 3 (March 1, 1995): R666—R675. http://dx.doi.org/10.1152/ajpregu.1995.268.3.r666.
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The amygdala is critical for behavioral arousal and must therefore integrate a wide variety of inputs. We examined sensory inputs and the degree of convergence to single neurons in the amygdala in conscious freely moving cats. A pressor stimulus elicited responses, predominantly inhibitory, in one-half of the amygdalar neurons tested. Most neurons in the central and basal nuclei responded to carotid chemoreceptor activation typically with an excitation. Almost one-half of all amygdalar neurons tested, particularly in the central nucleus, received orthodromic input from the locus ceruleus, the substantia nigra, and/or the contralateral central nucleus of the amygdala. Exteroceptive sensory stimulation with optic, acoustic, tactile, and olfactory stimuli elicited responses in 33, 55, 39, and 59% of amygdalar neurons, respectively. Two-thirds of the neurons tested with more than one external stimulus modality responded in the same manner to the various stimuli (usually excitation), demonstrating a convergence of exteroceptive stimuli on single amygdalar neurons, particularly in the basal nucleus. Spontaneous and induced behavioral arousal elicited responses in 92 and 86% of neurons, respectively. Most neurons responded to multimodal exteroceptive stimuli and behavioral arousal in the same manner. We suggest that amygdalar inputs are highly varied and, in many cases, relatively nonspecific and that the amygdala integrates a large number of external and internal sensory modalities to regulate autonomic and behavioral responsiveness to various stimuli.
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Luo, Wenting, Yue Zhang, Zhaoxian Yan, Xian Liu, Xiaoyan Hou, Weicui Chen, Yongsong Ye, Hui Li, and Bo Liu. "The Instant Effects of Continuous Transcutaneous Auricular Vagus Nerve Stimulation at Acupoints on the Functional Connectivity of Amygdala in Migraine without Aura: A Preliminary Study." Neural Plasticity 2020 (December 10, 2020): 1–13. http://dx.doi.org/10.1155/2020/8870589.
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Background. A growing body of evidence suggests that both auricular acupuncture and transcutaneous auricular vagus nerve stimulation (taVNS) can induce antinociception and relieve symptoms of migraine. However, their instant effects and central treatment mechanism remain unclear. Many studies proved that the amygdalae play a vital role not only in emotion modulation but also in pain processing. In this study, we investigated the modulation effects of continuous taVNS at acupoints on the FC of the bilateral amygdalae in MwoA. Methods. Thirty episodic migraineurs were recruited for the single-blind, crossover functional magnetic resonance imaging (fMRI) study. Each participant attended two kinds of eight-minute stimulations, taVNS and sham-taVNS (staVNS), separated by seven days in random order. Finally, 27 of them were included in the analysis of seed-to-voxel FC with the left/right amygdala as seeds. Results. Compared with staVNS, the FC decreased during taVNS between the left amygdala and left middle frontal gyrus (MFG), left dorsolateral superior frontal gyrus, right supplementary motor area (SMA), bilateral paracentral lobules, bilateral postcingulum gyrus, and right frontal superior medial gyrus, so did the FC of the right amygdala and left MFG. A significant positive correlation was observed between the FC of the left amygdala and right SMA and the frequency/total time of migraine attacks during the preceding four weeks. Conclusion. Continuous taVNS at acupoints can modulate the FC between the bilateral amygdalae and pain-related brain regions in MwoA, involving the limbic system, default mode network, and pain matrix, with obvious differences between the left amygdala and the right amygdala. The taVNS may produce treatment effects by modulating the abnormal FC of the amygdala and pain networks, possibly having the same central mechanism as auricular acupuncture.
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Perez-Diaz, Oscar, Daylín Góngora, José L. González-Mora, Katya Rubia, Alfonso Barrós-Loscertales, and Sergio Elías Hernández. "Enhanced amygdala–anterior cingulate white matter structural connectivity in Sahaja Yoga Meditators." PLOS ONE 19, no. 3 (March 28, 2024): e0301283. http://dx.doi.org/10.1371/journal.pone.0301283.
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Objective To study the white matter connections between anterior cingulate cortex, anterior insula and amygdala as key regions of the frontal-limbic network that have been related to meditation. Design Twenty experienced practitioners of Sahaja Yoga Meditation and twenty nonmeditators matched on age, gender and education level, were scanned using Diffusion Weighted Imaging, using a 3T scanner, and their white matter connectivity was compared using diffusion tensor imaging analyses. Results There were five white matter fiber paths in which meditators showed a larger number of tracts, two of them connecting the same area in both hemispheres: the left and right amygdalae and the left and right anterior insula; and the other three connecting left anterior cingulate with the right anterior insula, the right amygdala and the left amygdala. On the other hand, non-meditators showed larger number of tracts in two paths connecting the left anterior insula with the left amygdala, and the left anterior insula with the left anterior cingulate. Conclusions The study shows that long-term practice of Sahaja Yoga Meditation is associated with larger white matter tracts strengthening interhemispheric connections between limbic regions and connections between cingulo-amygdalar and cingulo-insular brain regions related to top-down attentional and emotional processes as well as between top-down control functions that could potentially be related to the witness state perceived through the state of mental silence promoted with this meditation. On the other hand, reduced connectivity strength in left anterior insula in the meditation group could be associated to reduced emotional processing affecting top-down processes.
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Wieser, Heinz Gregor. "Mesial temporal lobe epilepsy versus amygdalar epilepsy: Late seizure recurrence after initially successful amygdalotomy and regained seizure control following hippocampectomy." Epileptic Disorders 2, no. 3 (September 2000): 141–51. http://dx.doi.org/10.1684/j.1950-6945.2000.tb00374.x.
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ABSTRACT We summarise the concept of mesial temporal lobe epilepsy and the pros and cons in order to define amygdala epilepsy. We present a patient with stereotactically proven right amygdalar seizure onset, associated with fear and vegetative autonomic signs and symptoms as the most prominent clinical ictal features. Following a right stereotactic amygdalotomy, the patient experienced an 11‐year seizure‐free period. Similar, but not identical, semeiology of complex partial seizures then recurred. A right‐sided selective hippocampectomy and excision of the previously lesioned amygdala was performed. Except for 2 complex partial seizures associated with withdrawal of antiepileptic drugs, the patient remained seizure‐free 9.5 years. This case underscores the important role of the amygdala in generating the semiology, and raises several questions concerning the existence of “amygdalar epilepsy”. The 11‐year seizure‐free period following the stereotactic destruction of the amygdala is a strong argument for this notion. The late seizure recurrence requiring a second operation might, however, be seen as an argument for the important role of the hippocampal formation in the syndrome of mesial temporal lobe epilepsy even when the amygdala has been identified as the seizure onset zone. The role of stereotactic amygdalotomy is briefly reviewed.
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Joseph, JT. "The Amygdala in Neurodegeneration." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 48, s1 (May 2021): S5—S6. http://dx.doi.org/10.1017/cjn.2021.97.
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The amygdala is a key anatomic structure that has multiple different nuclei and is involved in several critical aspects of cognition and systemic functions. Several different neurodegenerative diseases have major pathological effects on distinct amygdala nuclei. This presentation will describe the classic and characteristic anatomic distributions in the amygdala of “pure” Alzheimer disease and “pure” Lewy body disease, as well as “normal aging”. In addition, data will be presented on how these classic distributions are altered in either “mixed dementias” or in some atypical forms of neurodegeneration. Amygdala pathology will also be illustrated in several other neurodegenerative diseases. The implications of the differing anatomic distributions in different neurodegenerative diseases will be discussed.LEARNING OBJECTIVESThis presentation will enable the learner to:Recognize key anatomic divisions of the amygdala 1.Describe how different neurodegenerative diseases affect the amygdala2.Consider how anatomic specificity of protein aggregation is important in the classification of neurodegenerative diseases
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Wei, Yuanyuan, Nianwei Huang, Yong Liu, Xi Zhang, Silun Wang, and Xiaoying Tang. "Hippocampal and Amygdalar Morphological Abnormalities in Alzheimer’s Disease Based on Three Chinese MRI Datasets." Current Alzheimer Research 17, no. 13 (March 2, 2021): 1221–31. http://dx.doi.org/10.2174/1567205018666210218150223.
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Background: Early detection of Alzheimer’s disease (AD) and its early stage, the mild cognitive impairment (MCI), has important scientific, clinical and social significance. Magnetic resonance imaging (MRI) based statistical shape analysis provides an opportunity to detect regional structural abnormalities of brain structures caused by AD and MCI. Objective: In this work, we aimed to employ a well-established statistical shape analysis pipeline, in the framework of large deformation diffeomorphic metric mapping, to identify and quantify the regional shape abnormalities of the bilateral hippocampus and amygdala at different prodromal stages of AD, using three Chinese MRI datasets collected from different domestic hospitals. Methods: We analyzed the region-specific shape abnormalities at different stages of the neuropathology of AD by comparing the localized shape characteristics of the bilateral hippocampi and amygdalas between healthy controls and two disease groups (MCI and AD). In addition to group comparison analyses, we also investigated the association between the shape characteristics and the Mini Mental State Examination (MMSE) of each structure of interest in the disease group (MCI and AD combined) as well as the discriminative power of different morphometric biomarkers. Results: We found the strongest disease pathology (regional atrophy) at the subiculum and CA1 subregions of the hippocampus and the basolateral, basomedial as well as centromedial subregions of the amygdala. Furthermore, the shape characteristics of the hippocampal and amygdalar subregions exhibiting the strongest AD related atrophy were found to have the most significant positive associations with the MMSE. Employing the shape deformation marker of the hippocampus or the amygdala for automated MCI or AD detection yielded a significant accuracy boost over the corresponding volume measurement. Conclusion: Our results suggested that the amygdalar and hippocampal morphometrics, especially those of shape morphometrics, can be used as auxiliary indicators for monitoring the disease status of an AD patient.
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Markowitsch, Hans J. "Differential Contribution of Right and Left Amygdala to Affective Information Processing." Behavioural Neurology 11, no. 4 (1999): 233–44. http://dx.doi.org/10.1155/1999/180434.
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Evidence for a differential involvement of the human left and right amygdala in emotional and cognitive behaviour is reviewed, with a particular emphasis on functional imaging results and case reports on patients with amygdalar damage. The available evidence allows one to conclude that there is definitely a hemisphere specific processing difference between the left and right amygdala. However, between studies the direction of the asymmetry is partly incongruent. In spite of this, the following tentative proposals are made: the left amygdala is more closely related to affective information encoding with a higher affinity to language and to detailed feature extraction, and the right amygdala to affective information retrieval with a higher affinity to pictorial or image-related material. Furthermore, the right amygdala may be more strongly engaged than the left one in a fast, shallow or gross analysis of affect-related information.
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Bernabe, Cristian S., Izabela F. Caliman, William A. Truitt, Andrei I. Molosh, Christopher A. Lowry, Anders Hay-Schmidt, Anantha Shekhar, and Philip L. Johnson. "Using loss- and gain-of-function approaches to target amygdala-projecting serotonergic neurons in the dorsal raphe nucleus that enhance anxiety-related and conditioned fear behaviors." Journal of Psychopharmacology 34, no. 4 (March 10, 2020): 400–411. http://dx.doi.org/10.1177/0269881119900981.
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Background: The central serotonergic system originating from the dorsal raphe nucleus (DR) plays a critical role in anxiety and trauma-related disorders such as posttraumatic stress disorder. Although many studies have investigated the role of serotonin (5-HT) within pro-fear brain regions such as the amygdala, the majority of these studies have utilized non-selective pharmacological approaches or poorly understood lesioning techniques which limit their interpretation. Aim: Here we investigated the role of amygdala-projecting 5-HT neurons in the DR in innate anxiety and conditioned fear behaviors. Methods: To achieve this goal, we utilized (1) selective lesion of 5-HT neurons projecting to the amygdala with saporin toxin conjugated to anti-serotonin transporter (SERT) injected into the amygdala, and (2) optogenetic excitation of amygdala-projecting DR cell bodies with a combination of a retrogradely transported canine adenovirus-expressing Cre-recombinase injected into the amygdala and a Cre-dependent-channelrhodopsin injected into the DR. Results: While saporin treatment lesioned both local amygdalar 5-HT fibers and neurons in the DR as well as reduced conditioned fear behavior, optical activation of amygdala-projecting DR neurons enhanced anxious behavior and conditioned fear response. Conclusion: Collectively, these studies support the hypothesis that amygdala-projecting 5-HT neurons in the DR represent an anxiety and fear-on network.
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Liu, Janelle, Jessica B. Girault, Tomoyuki Nishino, Mark D. Shen, Sun Hyung Kim, Catherine A. Burrows, Jed T. Elison, et al. "Atypical functional connectivity between the amygdala and visual, salience regions in infants with genetic liability for autism." Cerebral Cortex 34, no. 13 (May 1, 2024): 30–39. http://dx.doi.org/10.1093/cercor/bhae092.
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Abstract The amygdala undergoes a period of overgrowth in the first year of life, resulting in enlarged volume by 12 months in infants later diagnosed with ASD. The overgrowth of the amygdala may have functional consequences during infancy. We investigated whether amygdala connectivity differs in 12-month-olds at high likelihood (HL) for ASD (defined by having an older sibling with autism), compared to those at low likelihood (LL). We examined seed-based connectivity of left and right amygdalae, hypothesizing that the HL and LL groups would differ in amygdala connectivity, especially with the visual cortex, based on our prior reports demonstrating that components of visual circuitry develop atypically and are linked to genetic liability for autism. We found that HL infants exhibited weaker connectivity between the right amygdala and the left visual cortex, as well as between the left amygdala and the right anterior cingulate, with evidence that these patterns occur in distinct subgroups of the HL sample. Amygdala connectivity strength with the visual cortex was related to motor and communication abilities among HL infants. Findings indicate that aberrant functional connectivity between the amygdala and visual regions is apparent in infants with genetic liability for ASD and may have implications for early differences in adaptive behaviors.
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Schaefer, Stacey M., Daren C. Jackson, Richard J. Davidson, Geoffrey K. Aguirre, Daniel Y. Kimberg, and Sharon L. Thompson-Schill. "Modulation of Amygdalar Activity by the Conscious Regulation of Negative Emotion." Journal of Cognitive Neuroscience 14, no. 6 (August 1, 2002): 913–21. http://dx.doi.org/10.1162/089892902760191135.
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Lesion and neuroimaging studies suggest the amygdala is important in the perception and production of negative emotion; however, the effects of emotion regulation on the amygdalar response to negative stimuli remain unknown. Using event-related fMRI, we tested the hypothesis that voluntary modulation of negative emotion is associated with changes in neural activity within the amygdala. Negative and neutral pictures were presented with instructions to either “maintain” the emotional response or “passively view” the picture without regulating the emotion. Each picture presentation was followed by a delay, after which subjects indicated how they currently felt via a response keypad. Consistent with previous reports, greater signal change was observed in the amygdala during the presentation of negative compared to neutral pictures. No significant effect of instruction was found during the picture presentation component of the trial. However, a prolonged increase in signal change was observed in the amygdala when subjects maintained the negative emotional response during the delay following negative picture offset. This increase in amygdalar signal due to the active maintenance of negative emotion was significantly correlated with subjects' self-reported dispositional levels of negative affect. These results suggest that consciously evoked cognitive mechanisms that alter the emotional response of the subject operate, at least in part, by altering the degree of neural activity within the amygdala.
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Kim, Earnest, Eun Joo Kim, Regina Yeh, Minkyung Shin, Jake Bobman, Franklin B. Krasne, and Jeansok J. Kim. "Amygdaloid and non-amygdaloid fear both influence avoidance of risky foraging in hungry rats." Proceedings of the Royal Society B: Biological Sciences 281, no. 1790 (September 7, 2014): 20133357. http://dx.doi.org/10.1098/rspb.2013.3357.
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Considerable evidence seems to show that emotional and reflex reactions to feared situations are mediated by the amygdala. It might therefore seem plausible to expect that amygdala-coded fear should also influence decisions when animals make choices about instrumental actions. However, there is not good evidence of this. In particular, it appears, though the literature is conflicted, that once learning is complete, the amygdala may often not be involved in instrumental avoidance behaviours. It is therefore of interest that we have found in rats living for extended periods in a semi-naturalistic ‘closed economy’, where they were given random shocks in regions that had to be entered to obtain food, choices about feeding behaviour were in fact influenced by amygdala-coded fear, in spite of the null effect of amygdalar lesions on fear of dangerous location per se . We suggest that avoidance of highly motivated voluntary behaviour does depend in part on fear signals originating in the amygdala. Such signalling may be one role of well-known projections from amygdala to cortico-striate circuitry.
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Guyer, Amanda E., Christopher S. Monk, Erin B. McClure-Tone, Eric E. Nelson, Roxann Roberson-Nay, Abby D. Adler, Stephen J. Fromm, Ellen Leibenluft, Daniel S. Pine, and Monique Ernst. "A Developmental Examination of Amygdala Response to Facial Expressions." Journal of Cognitive Neuroscience 20, no. 9 (September 2008): 1565–82. http://dx.doi.org/10.1162/jocn.2008.20114.
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Several lines of evidence implicate the amygdala in face-emotion processing, particularly for fearful facial expressions. Related findings suggest that face-emotion processing engages the amygdala within an interconnected circuitry that can be studied using a functional-connectivity approach. Past work also underscores important functional changes in the amygdala during development. Taken together, prior research on amygdala function and development reveals a need for more work examining developmental changes in the amygdala's response to fearful faces and in amygdala functional connectivity during face processing. The present study used event-related functional magnetic resonance imaging to compare 31 adolescents (9–17 years old) and 30 adults (21–40 years old) on activation to fearful faces in the amygdala and other regions implicated in face processing. Moreover, these data were used to compare patterns of amygdala functional connectivity in adolescents and adults. During passive viewing, adolescents demonstrated greater amygdala and fusiform activation to fearful faces than did adults. Functional connectivity analysis revealed stronger connectivity between the amygdala and the hippocampus in adults than in adolescents. Within each group, variability in age did not correlate with amygdala response, and sex-related developmental differences in amygdala response were not found. Eye movement data collected outside of the magnetic resonance imaging scanner using the same task suggested that developmental differences in amygdala activation were not attributable to differences in eye-gaze patterns. Amygdala hyperactivation in response to fearful faces may explain increased vulnerability to affective disorders in adolescence; stronger amygdala-hippocampus connectivity in adults than adolescents may reflect maturation in learning or habituation to facial expressions.
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Gerlach, Gabriele, and Mario F. Wullimann. "Neural pathways of olfactory kin imprinting and kin recognition in zebrafish." Cell and Tissue Research 383, no. 1 (January 2021): 273–87. http://dx.doi.org/10.1007/s00441-020-03378-4.
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Abstract Teleost fish exhibit extraordinary cognitive skills that are comparable to those of mammals and birds. Kin recognition based on olfactory and visual imprinting requires neuronal circuits that were assumed to be necessarily dependent on the interaction of mammalian amygdala, hippocampus, and isocortex, the latter being a structure that teleost fish are lacking. We show that teleosts—beyond having a hippocampus and pallial amygdala homolog—also have subpallial amygdalar structures. In particular, we identify the medial amygdala and neural olfactory central circuits related to kin imprinting and kin recognition corresponding to an accessory olfactory system despite the absence of a separate vomeronasal organ.
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Thijssen, Sandra, Ryan L. Muetzel, Marian J. Bakermans-Kranenburg, Vincent W. V. Jaddoe, Henning Tiemeier, Frank C. Verhulst, Tonya White, and Marinus H. Van Ijzendoorn. "Insensitive parenting may accelerate the development of the amygdala–medial prefrontal cortex circuit." Development and Psychopathology 29, no. 2 (April 12, 2017): 505–18. http://dx.doi.org/10.1017/s0954579417000141.
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AbstractThis study examined whether the association between age and amygdala–medial prefrontal cortex (mPFC) connectivity in typically developing 6- to 10-year-old children is correlated with parental care. Resting-state functional magnetic resonance imaging scans were acquired from 124 children of the Generation R Study who at 4 years old had been observed interacting with their parents to assess maternal and paternal sensitivity. Amygdala functional connectivity was assessed using a general linear model with the amygdalae time series as explanatory variables. Higher level analyses assessing Sensitivity × Age as well as exploratory Sensitivity × Age × Gender interaction effects were performed restricted to voxels in the mPFC. We found significant Sensitivity × Age interaction effects on amygdala–mPFC connectivity. Age was related to stronger amygdala–mPFC connectivity in children with a lower combined parental sensitivity score (b = 0.11, p = .004, b = 0.06, p = .06, right and left amygdala, respectively), but not in children with a higher parental sensitivity score, (b = –0.07, p = .12, b = –0.06, p = .12, right and left amygdala, respectively). A similar effect was found for maternal sensitivity, with stronger amygdala–mPFC connectivity in children with less sensitive mothers. Exploratory (parental, maternal, paternal) Sensitivity × Age × Gender interaction analyses suggested that this effect was especially pronounced in girls. Amygdala-mPFC resting-state functional connectivity has been shown to increase from age 10.5 years onward, implying that the positive association between age and amygdala–mPFC connectivity in 6- to 10-year-old children of less sensitive parents represents accelerated development of the amygdala–mPFC circuit.
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Kogler, Lydia, Veronika I. Müller, Ewald Moser, Christian Windischberger, Ruben C. Gur, Ute Habel, Simon B. Eickhoff, and Birgit Derntl. "Testosterone and the Amygdala’s Functional Connectivity in Women and Men." Journal of Clinical Medicine 12, no. 20 (October 13, 2023): 6501. http://dx.doi.org/10.3390/jcm12206501.
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The amygdala contains androgen receptors and is involved in various affective and social functions. An interaction between testosterone and the amygdala’s functioning is likely. We investigated the amygdala’s resting-state functional connectivity (rsFC) network in association with testosterone in 94 healthy young adult women and men (final data available for analysis from 42 women and 39 men). Across the whole sample, testosterone was positively associated with the rsFC between the right amygdala and the right middle occipital gyrus, and it further predicted lower agreeableness scores. Significant sex differences appeared for testosterone and the functional connectivity between the right amygdala and the right superior frontal gyrus (SFG), showing higher testosterone levels with lower connectivity in women. Sex further predicted the openness and agreeableness scores. Our results show that testosterone modulates the rsFC between brain areas involved in affective processing and executive functions. The data indicate that the cognitive control of the amygdala via the frontal cortex is dependent on the testosterone levels in a sex-specific manner. Testosterone seems to express sex-specific patterns (1) in networks processing affect and cognition, and (2) in the frontal down-regulation of the amygdala. The sex-specific coupling between the amygdala and the frontal cortex in interaction with the hormone levels may drive sex-specific differences in a variety of behavioral phenomena that are further associated with psychiatric illnesses that show sex-specific prevalence rates.
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Garcia-Calero, Elena, and Luis Puelles. "Development of the mouse anterior amygdalar radial unit marked by Lhx9-expression." Brain Structure and Function 226, no. 2 (January 30, 2021): 575–600. http://dx.doi.org/10.1007/s00429-020-02201-8.
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AbstractThe amygdala in mammals plays a key role in emotional processing and learning, being subdivided in pallial and subpallial derivatives. Recently, the cortical ring model and the pallial amygdalar radial model (Puelles et al. 2019; Garcia-Calero et al. 2020) described the pallial amygdala as an histogenetic field external to the allocortical ring, and subdivided it in five major radial domains called lateral, basal, anterior, posterior and retroendopiriform units. The anterior radial unit, whose cells typically express the Lhx9 gene (see molecular profile in Garcia-Calero et al. 2020), is located next to the pallial/subpallial boundary. This radial domain shows massive radial translocation and accumulation of its derivatives into its intermediate and superficial strata, with only a glial palisade representing its final periventricular domain. To better understand the development of this singular radial domain, not described previously, we followed the expression of Lhx9 during mouse amygdalar development in the context of the postulated radial subdivisions of the pallial amygdala and other telencephalic developmental features.
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Warnell, Katherine Rice, Meredith Pecukonis, and Elizabeth Redcay. "Developmental relations between amygdala volume and anxiety traits: Effects of informant, sex, and age." Development and Psychopathology 30, no. 4 (November 21, 2017): 1503–15. http://dx.doi.org/10.1017/s0954579417001626.
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AbstractAlthough substantial human and animal evidence suggests a role for the amygdala in anxiety, literature linking amygdala volume to anxiety symptomatology is inconclusive, with studies finding positive, negative, and null results. Clarifying this brain–behavior relation in middle to late childhood is especially important, as this is a time both of amygdala structural maturation and the emergence of many anxiety disorders. The goal of the current study was to clarify inconsistent findings in previous literature by identifying factors moderating the relation between amygdala volume and anxiety traits in a large sample of typically developing children aged 6–13 years (N = 72). In particular, we investigated the moderating effects of informant (parent vs. child), age, and sex. We found that children's reports (i.e., self-reports) were related to amygdala volume; children who reported higher anxiety levels had smaller amygdalae. This negative relation between amygdala volume and anxiety weakened with age. There was also an independent effect of sex, such that relations were stronger in males than in females. These results indicate the importance of considering sample and informant characteristics when charting the neurobiological mechanisms underlying developmental anxiety.
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Gaier, E. D., R. M. Rodriguiz, J. Zhou, M. Ralle, W. C. Wetsel, B. A. Eipper, and R. E. Mains. "In vivo and in vitro analyses of amygdalar function reveal a role for copper." Journal of Neurophysiology 111, no. 10 (May 15, 2014): 1927–39. http://dx.doi.org/10.1152/jn.00631.2013.
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Mice with a single copy of the peptide amidating monooxygenase ( Pam) gene (PAM+/−) are impaired in contextual and cued fear conditioning. These abnormalities coincide with deficient long-term potentiation (LTP) at excitatory thalamic afferent synapses onto pyramidal neurons in the lateral amygdala. Slice recordings from PAM+/− mice identified an increase in GABAergic tone (Gaier ED, Rodriguiz RM, Ma XM, Sivaramakrishnan S, Bousquet-Moore D, Wetsel WC, Eipper BA, Mains RE. J Neurosci 30: 13656–13669, 2010). Biochemical data indicate a tissue-specific deficit in Cu content in the amygdala; amygdalar expression of Atox-1 and Atp7a, essential for transport of Cu into the secretory pathway, is reduced in PAM+/− mice. When PAM+/− mice were fed a diet supplemented with Cu, the impairments in fear conditioning were reversed, and LTP was normalized in amygdala slice recordings. A role for endogenous Cu in amygdalar LTP was established by the inhibitory effect of a brief incubation of wild-type slices with bathocuproine disulfonate, a highly selective, cell-impermeant Cu chelator. Interestingly, bath-applied CuSO4 had no effect on excitatory currents but reversibly potentiated the disynaptic inhibitory current. Bath-applied CuSO4 was sufficient to potentiate wild-type amygdala afferent synapses. The ability of dietary Cu to affect signaling in pathways that govern fear-based behaviors supports an essential physiological role for Cu in amygdalar function at both the synaptic and behavioral levels. This work is relevant to neurological and psychiatric disorders in which disturbed Cu homeostasis could contribute to altered synaptic transmission, including Wilson's, Menkes, Alzheimer's, and prion-related diseases.
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Cardinale, Elise M., Justin Reber, Katherine O'Connell, Peter E. Turkeltaub, Daniel Tranel, Tony W. Buchanan, and Abigail A. Marsh. "Bilateral amygdala damage linked to impaired ability to predict others' fear but preserved moral judgements about causing others fear." Proceedings of the Royal Society B: Biological Sciences 288, no. 1943 (January 27, 2021): 20202651. http://dx.doi.org/10.1098/rspb.2020.2651.
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The amygdala is a subcortical structure implicated in both the expression of conditioned fear and social fear recognition. Social fear recognition deficits following amygdala lesions are often interpreted as reflecting perceptual deficits, or the amygdala's role in coordinating responses to threats. But these explanations fail to capture why amygdala lesions impair both physiological and behavioural responses to multimodal fear cues and the ability to identify them. We hypothesized that social fear recognition deficits following amygdala damage reflect impaired conceptual understanding of fear. Supporting this prediction, we found specific impairments in the ability to predict others' fear (but not other emotions) from written scenarios following bilateral amygdala lesions. This finding is consistent with the suggestion that social fear recognition, much like social recognition of states like pain, relies on shared internal representations. Preserved judgements about the permissibility of causing others fear confirms suggestions that social emotion recognition and morality are dissociable.
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Garcia-Calero, Elena, Lara López-González, Margaret Martínez-de-la-Torre, Chen-Ming Fan, and Luis Puelles. "Sim1-expressing cells illuminate the origin and course of migration of the nucleus of the lateral olfactory tract in the mouse amygdala." Brain Structure and Function 226, no. 2 (January 25, 2021): 519–62. http://dx.doi.org/10.1007/s00429-020-02197-1.
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AbstractWe focus this report on the nucleus of the lateral olfactory tract (NLOT), a superficial amygdalar nucleus receiving olfactory input. Mixed with its Tbr1-expressing layer 2 pyramidal cell population (NLOT2), there are Sim1-expressing cells whose embryonic origin and mode of arrival remain unclear. We examined this population with Sim1-ISH and a Sim1-tauLacZ mouse line. An alar hypothalamic origin is apparent at the paraventricular area, which expresses Sim1 precociously. This progenitor area shows at E10.5 a Sim1-expressing dorsal prolongation that crosses the telencephalic stalk and follows the terminal sulcus, reaching the caudomedial end of the pallial amygdala. We conceive this Sim1-expressing hypothalamo-amygdalar corridor (HyA) as an evaginated part of the hypothalamic paraventricular area, which participates in the production of Sim1-expressing cells. From E13.5 onwards, Sim1-expressing cells migrated via the HyA penetrate the posterior pallial amygdalar radial unit and associate therein to the incipient Tbr1-expressing migration stream which swings medially past the amygdalar anterior basolateral nucleus (E15.5), crosses the pallio-subpallial boundary (E16.5), and forms the NLOT2 within the anterior amygdala by E17.5. We conclude that the Tbr1-expressing NLOT2 cells arise strictly within the posterior pallial amygdalar unit, involving a variety of required gene functions we discuss. Our results are consistent with the experimental data on NLOT2 origin reported by Remedios et al. (Nat Neurosci 10:1141–1150, 2007), but we disagree on their implication in this process of the dorsal pallium, observed to be distant from the amygdala.
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Chiao, Joan Y., Tetsuya Iidaka, Heather L. Gordon, Junpei Nogawa, Moshe Bar, Elissa Aminoff, Norihiro Sadato, and Nalini Ambady. "Cultural Specificity in Amygdala Response to Fear Faces." Journal of Cognitive Neuroscience 20, no. 12 (December 2008): 2167–74. http://dx.doi.org/10.1162/jocn.2008.20151.
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The human amygdala robustly activates to fear faces. Heightened response to fear faces is thought to reflect the amygdala's adaptive function as an early warning mechanism. Although culture shapes several facets of emotional and social experience, including how fear is perceived and expressed to others, very little is known about how culture influences neural responses to fear stimuli. Here we show that the bilateral amygdala response to fear faces is modulated by culture. We used functional magnetic resonance imaging to measure amygdala response to fear and nonfear faces in two distinct cultures. Native Japanese in Japan and Caucasians in the United States showed greater amygdala activation to fear expressed by members of their own cultural group. This finding provides novel and surprising evidence of cultural tuning in an automatic neural response.
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Bellani, M., M. Baiano, and P. Brambilla. "Brain anatomy of major depression II. Focus on amygdala." Epidemiology and Psychiatric Sciences 20, no. 1 (March 2011): 33–36. http://dx.doi.org/10.1017/s2045796011000096.
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Here, we briefly summarize the most consistent structural magnetic resonance imaging (MRI) studies on amygdala in major depression and debate the effects of clinical variables on amygdalar morphology.
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Inman, Cory S., Joseph R. Manns, Kelly R. Bijanki, David I. Bass, Stephan Hamann, Daniel L. Drane, Rebecca E. Fasano, Christopher K. Kovach, Robert E. Gross, and Jon T. Willie. "Direct electrical stimulation of the amygdala enhances declarative memory in humans." Proceedings of the National Academy of Sciences 115, no. 1 (December 18, 2017): 98–103. http://dx.doi.org/10.1073/pnas.1714058114.
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Emotional events are often remembered better than neutral events, a benefit that many studies have hypothesized to depend on the amygdala’s interactions with memory systems. These studies have indicated that the amygdala can modulate memory-consolidation processes in other brain regions such as the hippocampus and perirhinal cortex. Indeed, rodent studies have demonstrated that direct activation of the amygdala can enhance memory consolidation even during nonemotional events. However, the premise that the amygdala causally enhances declarative memory has not been directly tested in humans. Here we tested whether brief electrical stimulation to the amygdala could enhance declarative memory for specific images of neutral objects without eliciting a subjective emotional response. Fourteen epilepsy patients undergoing monitoring of seizures via intracranial depth electrodes viewed a series of neutral object images, half of which were immediately followed by brief, low-amplitude electrical stimulation to the amygdala. Amygdala stimulation elicited no subjective emotional response but led to reliably improved memory compared with control images when patients were given a recognition-memory test the next day. Neuronal oscillations in the amygdala, hippocampus, and perirhinal cortex during this next-day memory test indicated that a neural correlate of the memory enhancement was increased theta and gamma oscillatory interactions between these regions, consistent with the idea that the amygdala prioritizes consolidation by engaging other memory regions. These results show that the amygdala can initiate endogenous memory prioritization processes in the absence of emotional input, addressing a fundamental question and opening a path to future therapies.
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Anderson, Adam K., and Elizabeth A. Phelps. "Is the Human Amygdala Critical for the Subjective Experience of Emotion? Evidence of Intact Dispositional Affect in Patients with Amygdala Lesions." Journal of Cognitive Neuroscience 14, no. 5 (July 1, 2002): 709–20. http://dx.doi.org/10.1162/08989290260138618.
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It is thought that the human amygdala is a critical component of the neural substrates of emotional experience, involved particularly in the generation of fear, anxiety, and general negative affectivity. Although many neuroimaging studies demonstrate findings consistent this notion, little evidence of altered emotional experience following amygdala damage has been gathered in humans. In a preliminary test of the amygdala's role in phenomenal affective states, we assessed the extent of experienced positive and negative affective states in patients with amygdala damage and age-, sex-, and education-matched controls. To assess chronic changes in experienced affect, all groups were administered the Positive and Negative Affect Schedules (PANAS, Watson, Clark, & Tellegen, 1988). In the first study, we examined the effects of amygdala lesions on affective traits in 10 left and 10 right amygdala-damaged patients, 1 patient with bilateral amygdala damage (SP), and 20 control subjects. Subjects were asked to indicate the typicality of different experiential states of positive (e.g., inspired, excited) and negative (e.g., afraid, nervous) valence. In a second study, we examined more closely the effects of bilateral amygdala damage on the day-to-day generation of affective states by administering the PANAS daily for a 30-day period to patient SP and age-, sex-, and education-matched controls. In both experiments, no differences in the magnitude and frequency of self-reported positive or negative affect were found between control subjects and patients with amygdala damage. Moreover, principal components analyses of the covariation among different affects (across individuals in Study 1 and within individuals across days in Study 2) confirmed a two-factor (positive vs. negative) description of experienced affect in controls. A highly similar two-factor description of experienced affect was found in patients with amygdala lesions. This suggests that the underlying structure of affective states was intact following amygdala damage. It is concluded that the human amygdala may be recruited during phenomenal affective states in the intact brain, but is not necessary for the production of these states.
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Ait bali, Yassine, Nour-eddine Kaikai, Saadia Ba-M’hamed, Marco Sassoè-Pognetto, Maurizio Giustetto, and Mohamed Bennis. "Anxiety and Gene Expression Enhancement in Mice Exposed to Glyphosate-Based Herbicide." Toxics 10, no. 5 (April 29, 2022): 226. http://dx.doi.org/10.3390/toxics10050226.
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Growing evidence demonstrates that serotonin (5-HT) depletion increases activity in the amygdala and medial prefrontal cortex (mPFC), ultimately leading to anxiety behavior. Previously, we showed that glyphosate-based herbicides (GBHs) increased anxiety levels and reduced the number of serotoninergic fibers within the mPFCs and amygdalas of exposed mice. However, the impact of this 5-HT depletion following GBH exposure on neuronal activity in these structures is still unknown. In this study, we investigated the effects of GBH on immediate early gene (IEG) activation within the mPFCs and amygdalas of treated mice from juvenile age to adulthood and its subsequent effects on anxiety levels. Mice were treated for subchronic (6 weeks) and chronic (12 weeks) periods with 250 or 500 mg/kg/day of GBH and subjected to behavioral testing using the open field and elevated plus maze paradigms. Then, we analyzed the expression levels of c-Fos and pCREB and established the molecular proxies of neuronal activation within the mPFC and the amygdala. Our data revealed that repeated exposure to GBH triggers anxiogenic behavior in exposed mice. Confocal microscopy investigations into the prelimbic/infralimbic regions of the mPFC and in basolateral/central nuclei of the amygdala disclosed that the behavioral alterations are paralleled by a robust increase in the density and labelling intensity of c-Fos- and pCREB-positive cells. Taken together, these data show that mice exposed to GBH display the hyperactivation of the mPFC–amygdala areas, suggesting that this is a potential mechanism underlying the anxiety-like phenotype.
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Yasmin, Farhana, Roberto Colangeli, Maria Morena, Sarah Filipski, Mario van der Stelt, Quentin J. Pittman, Cecilia J. Hillard, et al. "Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala." Proceedings of the National Academy of Sciences 117, no. 1 (December 16, 2019): 650–55. http://dx.doi.org/10.1073/pnas.1910322116.
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Even a brief exposure to severe stress strengthens synaptic connectivity days later in the amygdala, a brain area implicated in the affective symptoms of stress-related psychiatric disorders. However, little is known about the synaptic signaling mechanisms during stress that eventually culminate in its delayed impact on the amygdala. Hence, we investigated early stress-induced changes in amygdalar synaptic signaling in order to prevent its delayed effects. Whole-cell recordings in basolateral amygdala (BLA) slices from rats revealed higher frequency of miniature excitatory postsynaptic currents (mEPSCs) immediately after 2-h immobilization stress. This was replicated by inhibition of cannabinoid receptors (CB1R), suggesting a role for endocannabinoid (eCB) signaling. Stress also reducedN-arachidonoylethanolamine (AEA), an endogenous ligand of CB1R. Since stress-induced activation of fatty acid amide hydrolase (FAAH) reduces AEA, we confirmed that oral administration of an FAAH inhibitor during stress prevents the increase in synaptic excitation in the BLA soon after stress. Although stress also caused an immediate reduction in synaptic inhibition, this was not prevented by FAAH inhibition. Strikingly, FAAH inhibition during the traumatic stressor was also effective 10 d later on the delayed manifestation of synaptic strengthening in BLA neurons, preventing both enhanced mEPSC frequency and increased dendritic spine-density. Thus, oral administration of an FAAH inhibitor during a brief stress prevents the early synaptic changes that eventually build up to hyperexcitability in the amygdala. This framework is of therapeutic relevance because of growing interest in targeting eCB signaling to prevent the gradual development of emotional symptoms and underlying amygdalar dysfunction triggered by traumatic stress.
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Ziccardi, Stefano, Marco Pitteri, Helen M. Genova, and Massimiliano Calabrese. "Social Cognition in Multiple Sclerosis: A 3-Year Follow-Up MRI and Behavioral Study." Diagnostics 11, no. 3 (March 9, 2021): 484. http://dx.doi.org/10.3390/diagnostics11030484.
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Social cognition (SC) has become a topic of widespread interest in the last decade. SC deficits were described in multiple sclerosis (MS) patients, in association with amygdala lesions, even in those without formal cognitive impairment. In this 3-year follow-up study, we aimed at longitudinally investigating the evolution of SC deficits and amygdala damage in a group of cognitive-normal MS patients, and the association between SC and psychological well-being. After 3 years (T3) from the baseline examination (T0), 26 relapsing-remitting MS patients (RRMS) were retested with a neuropsychological battery and SC tasks (theory of mind, facial emotion recognition, empathy). A SC composite score (SCcomp) was calculated for each patient. Emotional state, fatigue, and quality of life (QoL) were also evaluated. RRMS patients at T3 underwent a 3T-MRI as performed at T0, from which were calculated both volume and cortical lesion volume (CLV) of the amygdalae. Compared to T0, at T3 all RRMS patients were still cognitive-normal and remained stable in their global SC impaired performance. At T0, SCcomp correlated with amygdala CLV (p = 0.002) while, at T3, was more associated with amygdala volume (p = 0.035) rather than amygdala CLV (p = 0.043). SCcomp change T3-T0 correlated with global emotional state (p = 0.043), depression (p = 0.046), anxiety (p = 0.034), fatigue (p = 0.025), and QoL-social functioning (p = 0.033). We showed the longitudinal stability of SC deficits in cognitive-normal RRMS patients, mirroring the amygdala structural damage and the psychological well-being. These results highlight that SC exerts a key role in MS.
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ST. JACQUES, PEGGY L., BRANDY BESSETTE-SYMONS, and ROBERTO CABEZA. "Functional neuroimaging studies of aging and emotion: Fronto-amygdalar differences during emotional perception and episodic memory." Journal of the International Neuropsychological Society 15, no. 6 (November 2009): 819–25. http://dx.doi.org/10.1017/s1355617709990439.
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AbstractEmotional processes are enhanced in aging, such that aging is characterized by superior emotional regulation. This article provides a brief review of the neural bases supporting this effect with a focus on functional neuroimaging studies of perception and episodic memory. The most consistent finding across these studies is that older adults show an alteration in the recruitment of the amygdala, but greater recruitment of the frontal cortex. These Fronto-amygdalar Age-related Differences in Emotion (FADE) may reflect emotional regulation strategies mediated by frontal brain regions that dampen emotion-related activations in the amygdala. (JINS, 2009, 15, 819–825.)
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Zald, David H., Mathew C. Hagen, and José V. Pardo. "Neural Correlates of Tasting Concentrated Quinine and Sugar Solutions." Journal of Neurophysiology 87, no. 2 (February 1, 2002): 1068–75. http://dx.doi.org/10.1152/jn.00358.2001.
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Behavioral, ethological, and electrophysiological evidence suggests that the highly unpleasant, bitter taste of a concentrated quinine hydrochloride (QHCL) should activate the human amygdala. In the present study, healthy subjects tasted 0.02 M QHCL or water while regional cerebral blood flow (rCBF) was assayed with H2 15O PET. Subjects were also studied while tasting a pleasant sucrose solution and resting with eyes closed (ECR). Tasting QHCL significantly increased rCBF within the left amygdala relative to control conditions of tasting water and ECR. Sucrose and water caused small to moderate rCBF increases in the amygdala relative to ECR, but sucrose did not significantly increase activity within either amygdalae relative to water. In the frontal lobe, QHCL and sucrose both activated the right posterior orbitofrontal cortex (OFC) relative to water, but portions of the anterior OFC and inferior frontal pole showed valence specific responses to QHCL. These data indicate that the left amygdala responds robustly to QHCL and more moderately to nonaversive sapid stimuli, both pleasant and unpleasant gustatory stimuli activate the right posterior OFC, and the left inferior frontal pole/anterior OFC demonstrates valence-specific responses to aversive gustatory stimuli.
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Sripada, Chandra Sekhar, K. Luan Phan, Izelle Labuschagne, Robert Welsh, Pradeep J. Nathan, and Amanda G. Wood. "Oxytocin enhances resting-state connectivity between amygdala and medial frontal cortex." International Journal of Neuropsychopharmacology 16, no. 2 (May 30, 2012): 255–60. http://dx.doi.org/10.1017/s1461145712000533.
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Abstract The neuropeptide oxytocin (OXT) plays an important role in complex socio-affective behaviours such as affiliation, attachment, stress and anxiety. Previous studies have focused on the amygdala as an important target of OXT's effects. However, the effects of OXT on connectivity of the amygdala with cortical regions such as medial frontal cortex, an important mediator of social cognition and emotion regulation, remain unexplored. In a randomized, double-blind, cross-over design, 15 volunteers received intranasal OXT or placebo prior to resting-state functional magnetic resonance imaging. OXT significantly increased connectivity between both amygdalae and rostral medial frontal cortex (rmFC), while having only negligible effects on coupling with other brain regions. These results demonstrate that OXT is a robust and highly selective enhancer of amygdala connectivity with rmFC, a region critical to social cognition and emotion regulation, and add to our understanding of the neural mechanisms by which OXT modulates complex social and cognitive behaviours.
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MERVAALA, E., J. FÖHR, M. KÖNÖNEN, M. VALKONEN-KORHONEN, P. VAINIO, K. PARTANEN, J. PARTANEN, et al. "Quantitative MRI of the hippocampus and amygdala in severe depression." Psychological Medicine 30, no. 1 (January 2000): 117–25. http://dx.doi.org/10.1017/s0033291799001567.
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Background. There is little evidence to support possible structural changes in the amygdala and hippocampus of patients with severe depression.Methods. Quantitative MRI of the amygdala and hippocampus, as well as proton spectroscopy (MRS) of mesial temporal structures were studied in 34 drug-resistant in-patients with major depression and compared with 17 age-matched controls. Volumetric MRI data were normalized for brain size.Results. The volume of the left hippocampus was significantly smaller in the patients compared with the controls. Both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The patients, but not the controls, had significant asymmetry of the amygdalar volumes (right smaller than left). No differences were observed between the patients and controls in the T2 relaxation times for the hippocampus and amygdala. Mesial temporal lobe MRS revealed a significantly elevated choline/creatine ratio in the patients compared with the controls.Conclusions. This quantitative MRI study provides support for a possible association between structural and biochemical substrates and severe drug-resistant major depression.
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Gadziola, Marie A., Jasmine M. S. Grimsley, Sharad J. Shanbhag, and Jeffrey J. Wenstrup. "A novel coding mechanism for social vocalizations in the lateral amygdala." Journal of Neurophysiology 107, no. 4 (February 15, 2012): 1047–57. http://dx.doi.org/10.1152/jn.00422.2011.
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The amygdala plays a central role in evaluating the significance of acoustic signals and coordinating the appropriate behavioral responses. To understand how amygdalar responses modulate auditory processing and drive emotional expression, we assessed how neurons respond to and encode information that is carried within complex acoustic stimuli. We characterized responses of single neurons in the lateral nucleus of the amygdala to social vocalizations and synthetic acoustic stimuli in awake big brown bats. Neurons typically responded to most of the social vocalizations presented (mean = nine of 11 vocalizations) but differentially modulated both firing rate and response duration. Surprisingly, response duration provided substantially more information about vocalizations than did spike rate. In most neurons, variation in response duration depended, in part, on persistent excitatory discharge that extended beyond stimulus duration. Information in persistent firing duration was significantly greater than in spike rate, and the majority of neurons displayed more information in persistent firing, which was more likely to be observed in response to aggressive vocalizations (64%) than appeasement vocalizations (25%), suggesting that persistent firing may relate to the behavioral context of vocalizations. These findings suggest that the amygdala uses a novel coding strategy for discriminating among vocalizations and underscore the importance of persistent firing in the general functioning of the amygdala.
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Roy, Bhaskar, Michael Dunbar, Juhee Agrawal, Lauren Allen, and Yogesh Dwivedi. "Amygdala-Based Altered miRNome and Epigenetic Contribution of miR-128-3p in Conferring Susceptibility to Depression-Like Behavior via Wnt Signaling." International Journal of Neuropsychopharmacology 23, no. 3 (March 2020): 165–77. http://dx.doi.org/10.1093/ijnp/pyz071.
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Abstract Background Recent studies suggest that microRNAs (miRNAs) can participate in depression pathogenesis by altering a host of genes that are critical in corticolimbic functioning. The present study focuses on examining whether alterations in the miRNA network in the amygdala are associated with susceptibility or resiliency to develop depression-like behavior in rats. Methods Amygdala-specific altered miRNA transcriptomics were determined in a rat depression model following next-generation sequencing method. Target prediction analyses (cis- and trans) and qPCR-based assays were performed to decipher the functional role of altered miRNAs. miRNA-specific target interaction was determined using in vitro transfection assay in neuroblastoma cell line. miRNA-specific findings from the rat in vivo model were further replicated in postmortem amygdala of major depressive disorder (MDD) subjects. Results Changes in miRNome identified 17 significantly upregulated and 8 significantly downregulated miRNAs in amygdala of learned helpless (LH) compared with nonlearned helpless rats. Prediction analysis showed that the majority of the upregulated miRNAs had target genes enriched for the Wnt signaling pathway. Among altered miRNAs, upregulated miR-128-3p was identified as a top hit based on statistical significance and magnitude of change in LH rats. Target validation showed significant downregulation of Wnt signaling genes in amygdala of LH rats. A discernable increase in expression of amygdalar miR-128-3p along with significant downregulation of key target genes from Wnt signaling (WNT5B, DVL, and LEF1) was noted in MDD subjects. Overexpression of miR-128-3p in a cellular model lead to a marked decrease in the expression of Dvl1 and Lef1 genes, confirming them as validated targets of miR-128-3p. Additional evidence suggested that the amygdala-specific diminished expression of transcriptional repressor Snai1 could be potentially linked to induced miR-128-2 expression in LH rats. Furthermore, an amygdala-specific posttranscriptional switching mechanism could be active between miR-128-3p and RNA binding protein Arpp21 to gain control over their target genes such as Lef1. Conclusion Our study suggests that in amygdala a specific set of miRNAs may play an important role in depression susceptibility, which could potentially be mediated through Wnt signaling.
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Assari, Shervin. "Neighborhood Poverty and Amygdala Response to Negative Face." Journal of Economics and Public Finance 6, no. 4 (November 26, 2020): p67. http://dx.doi.org/10.22158/jepf.v6n4p67.
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Introduction: Considerable research has established a link between socioeconomic status (SES) and brain function. While studies have shown a link between poverty status and amygdala response to negative stimuli, a paucity of knowledge exists on whether neighborhood poverty is also independently associated with amygdala hyperactive response to negative stimuli. Purpose: Using functional brain imaging data, this study tested the association between neighborhood SES and the amygdala’s response to negative stimuli. Considering race as a sociological rather than a biological construct, we also explored racial heterogeneity in this association between non-Hispanic Black and non-Hispanic White youth. Methods: We borrowed the functional Magnetic Resonance Imaging (fMRI) data of the Adolescent Brain Cognitive Development (ABCD) study. The sample was 2,490 nine to ten years old non-Hispanic Black and non-Hispanic White adolescents. The independent variable was neighborhood income which was treated as a continuous measure. The primary outcomes were the right and left amygdala response to negative face during an N-Back task. Age, sex, race, marital status, and family SES were the covariates. To analyze the data, we used linear regression models. Results: Low neighborhood income was independently associated with a higher level of amygdala response to negative face. Similar results were seen for the right and left amygdala. These effects were significant net of race, age, sex, marital status, and family SES. An association between low neighborhood SES and higher left but not right amygdala response to negative face could be observed for non-Hispanic Black youth. No association between neighborhood SES and left or right amygdala response to negative face could be observed for non-Hispanic White youth. Conclusions: For American youth, particularly non-Hispanic Black youth, living in a poor neighborhood predicts the left amygdala reaction to negative face. This result suggested that Black youth who live in poor neighborhoods are at a high risk of poor emotion regulation. This finding has implications for policy making to reduce inequalities in undesired behavioral and emotional outcomes. Policy solutions to health inequalities should address inequalities in neighborhood SES.
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Papini, C., T. P. White, A. Montagna, P. J. Brittain, S. Froudist-Walsh, J. Kroll, V. Karolis, et al. "Altered resting-state functional connectivity in emotion-processing brain regions in adults who were born very preterm." Psychological Medicine 46, no. 14 (August 15, 2016): 3025–39. http://dx.doi.org/10.1017/s0033291716001604.
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BackgroundVery preterm birth (VPT; <32 weeks of gestation) has been associated with impairments in emotion regulation, social competence and communicative skills. However, the neuroanatomical mechanisms underlying such impairments have not been systematically studied. Here we investigated the functional integrity of the amygdala connectivity network in relation to the ability to recognize emotions from facial expressions in VPT adults.MethodThirty-six VPT-born adults and 38 age-matched controls were scanned at rest in a 3-T MRI scanner. Resting-state functional connectivity (rs-fc) was assessed with SPM8. A seed-based analysis focusing on three amygdalar subregions (centro-medial/latero-basal/superficial) was performed. Participants’ ability to recognize emotions was assessed using dynamic stimuli of human faces expressing six emotions at different intensities with the Emotion Recognition Task (ERT).ResultsVPT individuals compared to controls showed reduced rs-fc between the superficial subregion of the left amygdala, and the right posterior cingulate cortex (p = 0.017) and the left precuneus (p = 0.002). The VPT group further showed elevated rs-fc between the left superficial amygdala and the superior temporal sulcus (p = 0.008). Performance on the ERT showed that the VPT group was less able than controls to recognize anger at low levels of intensity. Anger scores were significantly associated with rs-fc between the superficial amygdala and the posterior cingulate cortex in controls but not in VPT individuals.ConclusionsThese findings suggest that alterations in rs-fc between the amygdala, parietal and temporal cortices could represent the mechanism linking VPT birth and deficits in emotion processing.
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Suvrathan, Aparna, Sharath Bennur, Supriya Ghosh, Anupratap Tomar, Shobha Anilkumar, and Sumantra Chattarji. "Stress enhances fear by forming new synapses with greater capacity for long-term potentiation in the amygdala." Philosophical Transactions of the Royal Society B: Biological Sciences 369, no. 1633 (January 5, 2014): 20130151. http://dx.doi.org/10.1098/rstb.2013.0151.
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Prolonged and severe stress leads to cognitive deficits, but facilitates emotional behaviour. Little is known about the synaptic basis for this contrast. Here, we report that in rats subjected to chronic immobilization stress, long-term potentiation (LTP) and NMDA receptor (NMDAR)-mediated synaptic responses are enhanced in principal neurons of the lateral amygdala, a brain area involved in fear memory formation. This is accompanied by electrophysiological and morphological changes consistent with the formation of ‘silent synapses’, containing only NMDARs. In parallel, chronic stress also reduces synaptic inhibition. Together, these synaptic changes would enable amygdalar neurons to undergo further experience-dependent modifications, leading to stronger fear memories. Consistent with this prediction, stressed animals exhibit enhanced conditioned fear. Hence, stress may leave its mark in the amygdala by generating new synapses with greater capacity for plasticity, thereby creating an ideal neuronal substrate for affective disorders. These findings also highlight the unique features of stress-induced plasticity in the amygdala that are strikingly different from the stress-induced impairment of structure and function in the hippocampus.
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Pearce, J. M. S. "Amygdala." European Neurology 59, no. 5 (2008): 283. http://dx.doi.org/10.1159/000115646.
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LeDoux, Joseph. "Amygdala." Scholarpedia 3, no. 4 (2008): 2698. http://dx.doi.org/10.4249/scholarpedia.2698.
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Tubbs, R. Shane, Joseph H. Miller, Aaron A. Cohen-Gadol, and Dennis D. Spencer. "Intraoperative Anatomic Landmarks for Resection of the Amygdala during Medial Temporal Lobe Surgery." Neurosurgery 66, no. 5 (May 1, 2010): 974–77. http://dx.doi.org/10.1227/01.neu.0000368105.64548.71.
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Abstract OBJECTIVE To establish reliable gross landmarks for resecting the amygdala intraoperatively, especially during anteromedial temporal lobectomy and amygdalohippocampectomy for epilepsy surgery. Reliable landmarks would allow its safe and complete resection as well as its potential en bloc removal for detailed electrophysiological and histopathological analyses. METHODS Ten adult cadavers (20 sides) were used. Two adjacent anatomic structures were identified: the bifurcation of the middle cerebral artery (MCA point) and the entry point of the anterior choroidal artery (AChoA) at the anterior origin of the choroid plexus into the temporal horn (inferior choroidal point referred to as the AChoA point). Following removal of the brain tissue inferior and anterior to the imaginary line connecting these 2 anatomic landmarks, cross sectional histopathological analysis of the remaining temporal and frontal lobes was performed to verify the presence or absence of any nervous tissue belonging to the amygdala complex. RESULTS In all 20 sides, the entire amygdala complex was found anterior and inferior to the transection made along the MCA-AChoA line. No apparent injury to the adjacent striatum was discovered. CONCLUSION Two easily identifiable points, including the middle cerebral artery bifurcation and the inferior choroidal point, may define a line that reliably disconnects the amygdala complex from the remaining temporal and frontal lobes. These landmarks may assist in resection of the amygdale while preserving important adjacent structures, including the striatum.
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Grabowska, Anna, Elżbieta Łuczywek, Ewa Fersten, Anna Herman, and Iwona Szatkowska. "Memory impairment in patients with stereotaxic lesions to the hippocampus and amygdala." Acta Neurobiologiae Experimentalis 54, no. 4 (December 31, 1994): 393–403. http://dx.doi.org/10.55782/ane-1994-1045.
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The study aimed at testing: (1) whether stereotaxic damage to the hippocampus and amygdala results in a memory deficit, (2) whether the memory functions subserved by the hippocampus are lateralized and (3) whether time limited storage of sensory information is impaired after focal hippocampal and amygdalar lesions. Seven patients with unilateral stereotaxic damage to the anterior part of hippocampus and unilateral or bilateral damage to the medial part of amygdala and 11 control subjects with no brain damage participated in the research. They were presented with memory tests that required either remembering a spatial arrangement of simultaneously presented verbal vs. nonverbal stimuli or a temporal order of sequentially presented items. Moreover, a sensory information storage test was used. The results indicate that even small damage limited to the anterior part of the hippocampus and medial part of the amygdala results in a mild memory deficit. Memory impairment was not related to the side of hippocampal lesion. This suggests that memory function subserved by the hippocampus is not lateralized. Differential effects of left and right lobectomies found in previous studies were, thus, probably due to the damage to temporal cortex. The results showed, however, that sensory information storage limited to 3 s is not impaired after focal damage to the hippocampus and amygdala. A clear lateralization effect showing right hemisphere advantage in that function was found.
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Wang, Shuo, Virginia Falvello, Jenny Porter, Christopher P. Said, and Alexander Todorov. "Behavioral and Neural Adaptation in Approach Behavior." Journal of Cognitive Neuroscience 30, no. 6 (June 2018): 885–97. http://dx.doi.org/10.1162/jocn_a_01243.
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People often make approachability decisions based on perceived facial trustworthiness. However, it remains unclear how people learn trustworthiness from a population of faces and whether this learning influences their approachability decisions. Here we investigated the neural underpinning of approach behavior and tested two important hypotheses: whether the amygdala adapts to different trustworthiness ranges and whether the amygdala is modulated by task instructions and evaluative goals. We showed that participants adapted to the stimulus range of perceived trustworthiness when making approach decisions and that these decisions were further modulated by the social context. The right amygdala showed both linear response and quadratic response to trustworthiness level, as observed in prior studies. Notably, the amygdala's response to trustworthiness was not modulated by stimulus range or social context, a possible neural dynamic adaptation. Together, our data have revealed a robust behavioral adaptation to different trustworthiness ranges as well as a neural substrate underlying approach behavior based on perceived facial trustworthiness.
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Iidaka, Tetsuya, Masao Omori, Tetsuhito Murata, Hirotaka Kosaka, Yoshiharu Yonekura, Tomohisa Okada, and Norihiro Sadato. "Neural Interaction of the Amygdala with the Prefrontal and Temporal Cortices in the Processing of Facial Expressions as Revealed by fMRI." Journal of Cognitive Neuroscience 13, no. 8 (November 1, 2001): 1035–47. http://dx.doi.org/10.1162/089892901753294338.
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Some involvement of the human amygdala in the processing of facial expressions has been investigated in neuroimaging studies, although the neural mechanisms underlying motivated or emotional behavior in response to facial stimuli are not yet fully understood. We investigated, using functional magnetic resonance imaging (fMRI) and healthy volunteers, how the amygdala interacts with other cortical regions while subjects are judging the sex of faces with negative, positive, or neutral emotion. The data were analyzed by a subtractive method, then, to clarify possible interaction among regions within the brain, several kinds of analysis (i.e., a correlation analysis, a psychophysiological interaction analysis and a structural equation modeling) were performed. Overall, significant activation was observed in the bilateral fusiform gyrus, medial temporal lobe, prefrontal cortex, and the right parietal lobe during the task. The results of subtraction between the conditions showed that the left amygdala, right orbitofrontal cortex, and temporal cortices were predominantly involved in the processing of the negative expressions. The right angular gyrus was involved in the processing of the positive expressions when the negative condition was subtracted from the positive condition. The correlation analysis showed that activity in the left amygdala positively correlated with activity in the left prefrontal cortex under the negative minus neutral subtraction condition. The psychophysiological interaction revealed that the neural responses in the left amygdala and the right prefrontal cortex underwent the condition-specific changes between the negative and positive face conditions. The right amygdaloid activity also had an interactive effect with activity in the right hippocampus and middle temporal gyrus. These results may suggest that the left and right amygdalae play a differential role in effective processing of facial expressions in collaboration with other cortical or subcortical regions, with the left being related with the bilateral prefrontal cortex, and the right with the right temporal lobe.
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Steinmetz, Peter N. "Alternate Task Inhibits Single-neuron Category-selective Responses in the Human Hippocampus while Preserving Selectivity in the Amygdala." Journal of Cognitive Neuroscience 21, no. 2 (February 2009): 347–58. http://dx.doi.org/10.1162/jocn.2008.21017.
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One fifth of neurons in the medial-temporal lobe of human epilepsy patients respond selectively to categories of images, such as faces or cars. Here we show that responses of hippocampal neurons are rapidly modified as subjects alternate (over 60 sec) between two tasks (1) identifying images from a category, or (2) playing a simple video game superimposed on the same images. Category-selective responses, present when a subject identifies categories, are eliminated when the subject shifts to playing the game for 87% of category-selective hippocampal neurons. By contrast, responses in the amygdala are present during both tasks for 72% of category-selective amygdalar neurons. These results suggest that attention to images is required to evoke selective responses from single neurons in the hippocampus, but is not required by neurons in the amygdala.
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Jain, Suman, Rashmi Mathur, Ratna Sharma, and Usha Nayar. "Recovery from Lesion-Associated Learning Deficits by Fetal Amygdala Transplants." Neural Plasticity 9, no. 1 (2002): 53–63. http://dx.doi.org/10.1155/np.2002.53.
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Bilateral lesions of the amygdaloid complex result in elimination or attenuation of the conditioned freezing that is normally seen in the conditioned emotional response (CER) paradigm and the active avoidance (AA) task. We observed the effect of amygdalar tissue transplantation on the ability of lesioned (central nucleus of amygdala, CeA) rats to learn CER and AA. In two groups of adult Wistar rats, sham operation or bilateral lesions of the CeA were produced electrolytically (2mA for 8 sec). In a third group, fetal amygdalar tissue was transplanted at the CeA-lesioned site 2 d postoperatively. All rats were trained on CER and AA from the6thpostoperative day. In comparison with the shamoperated group, bilaterally CeA-lesioned rats showed a significant (p<0.001) increase in all CER scores, indicating an acquisition deficit. After fetal amygdalar tissue transplantation, the CER scores significantly decreased (p<0.05) when compared with the lesioned group. A significant (p<0.01) decrease in the percentage of avoidance in the AA task occurring after CeA lesion returned to control values after amygdalar tissue transplantation. In conclusion, in CeA-lesioned rats a complete behavioral deficit in learning CER and AA was restored by transplanting fetal amygdalar tissue at the lesioned site.