Researchers Discover New Pathways in the Brain's Fear Center

Researchers are pioneering an innovative brain study that sheds light on how the amygdala portion of the brain functions and could contribute to a better understanding of post-traumatic stress disorder, anxiety, depression and Alzheimer’s disease.

Conditions such as PTSD, anxiety and depression are thought to be linked to the abnormal functioning of the amygdala, which is located within the temporal lobes and plays a key role in processing emotions, actions and cognition.

“This novel research paper provides anatomical and physiological evidence for the existence of a long-range inhibitory pathway from the auditory cortex to the amygdala in the mouse brain,” Alfonso Apicella, corresponding author, said. “For the first time, in our paper we show this emotional pathway.”

Apicella explained that advances in the techniques for labeling individual neuronal cells made it possible to study the individual neurons extending from the auditory cortex to the amygdala.

He added that the inhibitory cortical neurons can alter the activity of the amygdala’s principal neurons and can therefore directly control the output of the amygdala. The neurons contain a substance called somatostatin, and it regulates physiological functions and forms a connection with principal neurons that project to other brain regions outside the amygdala that are involved in fear and aversive behavior.

“The discovery that the amygdala receives both excitatory and inhibitory inputs from that cortex suggests that the timing and relative strength of these inputs can affect the activity of the amygdala,” Acipella said.

Apicella and his research team noted that future experiments should examine whether this is a general mechanism by which sensory stimuli can influence the processes controlled by the amygdala, such as fear/aversive behavior and how the disruption of this pathway can lead to several neurological and psychiatric disorders, such as Alzheimer’s, anxiety, depression and PTSD.

Research related to this topic will continue in Apicella’s lab. His research group investigates the neural basis of perception. More specifically, the researchers want to understand how cortical microcircuits process sensory information leading to behavioral outcomes. 

Reference

Bertero et al. (2019) A Non-Canonical Cortico-Amygdala Inhibitory Loop. Journal of Neuroscience. DOI: https://doi.org/10.1523/JNEUROSCI.1515-19.2019

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