amygdala-fear.ml


The phylogenetically ancient Amygdala: The neuroanatomical correlate of Fear, Anxiety, and Aggression

 

The amygdala (also corpus amygdaloideum; Greek, ἀμυγδαλή, amygdalē, ‘Almond’, ‘tonsil’) is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain in complex vertebrates, including humans. Shown in research to perform a primary role in the processing of memory, decision-making and emotional responses (including fear, anxiety, and aggression), the amygdalae are considered part of the limbic system.

Each side holds a specific function in how we perceive and process emotion. The right and left portions of the amygdala have independent memory systems, but work together to store, encode, and interpret emotion.

The right hemisphere is associated with negative emotion. t plays a role in the expression of fear and in the processing of fear-inducing stimuli. Fear conditioning, which occurs when a neutral stimulus acquires aversive properties, occurs within the right hemisphere. When an individual is presented with a conditioned, aversive stimulus, it is processed within the right amygdala, producing an unpleasant or fearful response. This emotional response conditions the individual to avoid fear-inducing stimuli and more importantly, to assess threats in the environment.

www.brainfacts.org/3d-brain#intro=false&focus=Brain-limbic_system-amygdala

Structure

Subdivisions of the mouse amygdala

The regions described as amygdala nuclei encompass several structures with distinct connectional and functional characteristics in humans and other animals. Among these nuclei are the basolateral complex, the cortical nucleus, the medial nucleus, the central nucleus, and the intercalated cell clusters. The basolateral complex can be further subdivided into the lateral, the basal, and the accessory basal nuclei.

MRI coronal view of the amygdala

MRI coronal view of the right amygdala

Anatomically, the amygdala, and more particularly its central and medial nuclei have sometimes been classified as a part of the basal ganglia.

Hemispheric specializations

There are functional differences between the right and left amygdala. In one study, electrical stimulations of the right amygdala induced negative emotions, especially fear and sadness. In contrast, stimulation of the left amygdala was able to induce either pleasant (happiness) or unpleasant (fear, anxiety, sadness) emotions. Other evidence suggests that the left amygdala plays a role in the brain’s reward system.


Further References

Baxter, M. G., & Murray, E. A.. (2002). The amygdala and reward. Nature Reviews Neuroscience

Plain numerical DOI: 10.1038/nrn875
DOI URL
directSciHub download

Li, H., Penzo, M. A., Taniguchi, H., Kopec, C. D., Huang, Z. J., & Li, B.. (2013). Experience-dependent modification of a central amygdala fear circuit. Nature Neuroscience, 16(3), 332–339.

Plain numerical DOI: 10.1038/nn.3322
DOI URL
directSciHub download

Morris, J. S., Ohman, A., & Dolan, R. J.. (1999). A subcortical pathway to the right amygdala mediating “unseen” fear. Proceedings of the National Academy of Sciences, 96(4), 1680–1685.

Plain numerical DOI: 10.1073/pnas.96.4.1680
DOI URL
directSciHub download

Phillips, R. G., & LeDoux, J. E.. (1992). Differential Contribution of Amygdala and Hippocampus to Cued and Contextual Fear Conditioning. Behavioral Neuroscience, 106(2), 274–285.

Plain numerical DOI: 10.1037/0735-7044.106.2.274
DOI URL
directSciHub download

Phelps, E. A., Delgado, M. R., Nearing, K. I., & Ledoux, J. E.. (2004). Extinction learning in humans: Role of the amygdala and vmPFC. Neuron, 43(6), 897–905.

Plain numerical DOI: 10.1016/j.neuron.2004.08.042
DOI URL
directSciHub download

Duvarci, S., & Pare, D.. (2014). Amygdala microcircuits controlling learned fear. Neuron

Plain numerical DOI: 10.1016/j.neuron.2014.04.042
DOI URL
directSciHub download

Ehrlich, I., Humeau, Y., Grenier, F., Ciocchi, S., Herry, C., & Lüthi, A.. (2009). Amygdala Inhibitory Circuits and the Control of Fear Memory. Neuron

Plain numerical DOI: 10.1016/j.neuron.2009.05.026
DOI URL
directSciHub download

LeDoux, J. E.. (2009). Emotion Circuits in the Brain. Focus, 7(2), 274–274.

Plain numerical DOI: 10.1176/foc.7.2.foc274
DOI URL
directSciHub download

Maren, S., & Quirk, G. J.. (2004). Neuronal signalling of fear memory. Nature Reviews Neuroscience

Plain numerical DOI: 10.1038/nrn1535
DOI URL
directSciHub download

Gross, C. T., & Canteras, N. S.. (2012). The many paths to fear. Nature Reviews Neuroscience

Plain numerical DOI: 10.1038/nrn3301
DOI URL
directSciHub download

Karalis, N., Dejean, C., Chaudun, F., Khoder, S., R Rozeske, R., Wurtz, H., … Herry, C.. (2016). 4-Hz oscillations synchronize prefrontal-amygdala circuits during fear behavior. Nature Neuroscience, 19(4), 605–612.

Plain numerical DOI: 10.1038/nn.4251
DOI URL
directSciHub download

Haubensak, W., Kunwar, P. S., Cai, H., Ciocchi, S., Wall, N. R., Ponnusamy, R., … Anderson, D. J.. (2010). Genetic dissection of an amygdala microcircuit that gates conditioned fear. Nature, 468(7321), 270–276.

Plain numerical DOI: 10.1038/nature09553
DOI URL
directSciHub download

Adolphs, R.. (2008). Fear, faces, and the human amygdala. Current Opinion in Neurobiology

Plain numerical DOI: 10.1016/j.conb.2008.06.006
DOI URL
directSciHub download

Kirsch, P.. (2005). Oxytocin Modulates Neural Circuitry for Social Cognition and Fear in Humans. Journal of Neuroscience, 25(49), 11489–11493.

Plain numerical DOI: 10.1523/JNEUROSCI.3984-05.2005
DOI URL
directSciHub download

Davis, M., Walker, D. L., Miles, L., & Grillon, C.. (2010). Phasic vs sustained fear in rats and humans: Role of the extended amygdala in fear vs anxiety. Neuropsychopharmacology

Plain numerical DOI: 10.1038/npp.2009.109
DOI URL
directSciHub download

SAH, P., FABER, E. S. L., LOPEZ DE ARMENTIA, M., & POWER, J.. (2003). The Amygdaloid Complex: Anatomy and Physiology. Physiological Reviews, 83(3), 803–834.

Plain numerical DOI: 10.1152/physrev.00002.2003
DOI URL
directSciHub download

Davis, M., & Whalen, P. J.. (2001). The amygdala: Vigilance and emotion. Molecular Psychiatry

Plain numerical DOI: 10.1038/sj.mp.4000812
DOI URL
directSciHub download

LeDoux, J.. (2003). The emotional brain, fear, and the amygdala. Cellular and Molecular Neurobiology

Plain numerical DOI: 10.1023/A:1025048802629
DOI URL
directSciHub download

Senn, V., Wolff, S. B. E., Herry, C., Grenier, F., Ehrlich, I., Gründemann, J., … Lüthi, A.. (2014). Long-range connectivity defines behavioral specificity of amygdala neurons. Neuron, 81(2), 428–437.

Plain numerical DOI: 10.1016/j.neuron.2013.11.006
DOI URL
directSciHub download

Ciocchi, S., Herry, C., Grenier, F., Wolff, S. B. E., Letzkus, J. J., Vlachos, I., … Lüthi, A.. (2010). Encoding of conditioned fear in central amygdala inhibitory circuits. Nature, 468(7321), 277–282.

Plain numerical DOI: 10.1038/nature09559
DOI URL
directSciHub download

Wolff, S. B. E., Gründemann, J., Tovote, P., Krabbe, S., Jacobson, G. A., Müller, C., … Lüthi, A.. (2014). Amygdala interneuron subtypes control fear learning through disinhibition. Nature, 509(7501), 453–458.

Plain numerical DOI: 10.1038/nature13258
DOI URL
directSciHub download

Feinstein, J. S., Adolphs, R., Damasio, A., & Tranel, D.. (2011). The human amygdala and the induction and experience of fear. Current Biology, 21(1), 34–38.

Plain numerical DOI: 10.1016/j.cub.2010.11.042
DOI URL
directSciHub download

Phelps, E. A., & LeDoux, J. E.. (2005). Contributions of the amygdala to emotion processing: From animal models to human behavior. Neuron

Plain numerical DOI: 10.1016/j.neuron.2005.09.025
DOI URL
directSciHub download

Olsson, A., & Phelps, E. A.. (2007). Social learning of fear. Nature Neuroscience

Plain numerical DOI: 10.1038/nn1968
DOI URL
directSciHub download

Adolphs, R.. (1997). Fear and the human amygdala. Neurocase, 3(4), 267–274.

Plain numerical DOI: 10.1093/neucas/3.4.267
DOI URL
directSciHub download