Inhibitory Loop Connects Auditory Cortex And Lateral Amygdala

Researchers at The University of Texas at San Antonio (UTSA) are pioneering an innovative brain study that sheds light on how the amygdala functions and could contribute to a better understanding of post-traumatic stress disorder, anxiety, depression, and Alzheimer’s disease.

“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. For the first time, in our paper, we show this emotional pathway,”

said Alfonso Apicella, an associate professor in the Department of Biology.

Inhibitory Cortical Neurons

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.

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.

Behavioral Processes

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 processes include 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.

[1] Alice Bertero, Paul Luc Caroline Feyen, Hector Zurita, Alfonso junior Apicella. A Non-Canonical Cortico-Amygdala Inhibitory Loop. Journal of Neuroscience 23 October 2019, 39 (43) 8424-8438; DOI: 10.1523/JNEUROSCI.1515-19.2019