A research group from The University of Texas at San Antonio (TX, USA) has identified a new fear pathway in mice between the auditory cortex and the lateral amygdala that may play a role in fear-related behavior driven by auditory stimuli. The results of the study, published in The Journal of Neuroscience, could aid further research into understanding the mechanisms of anxiety, depression and post-traumatic stress disorder.
Utilizing anatomical, electrophysiological, imaging and optogenetics approaches the authors of the study were able to analyze individual neuronal cells connecting the auditory cortex and the lateral amygdala in the brains of mice. They discovered that the amygdala received long-range inhibitory signals from the auditory cortex.
“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,” commented Alfonso Apicella (The University of Texas at San Antonio).
According to previous research, the amygdala, which performs a role in processing emotional responses such as fear and aggression, is considered to receive signals from the auditory cortex that are exclusively excitatory. However, this study has demonstrated that this may not be the case.
You might also like:
The group determined that the newly identified fear pathway contains inhibitory somatostatin neurons. These were able to directly inhibit the principal neurons of the amygdala.
“The discovery that the amygdala receives both excitatory and inhibitory inputs from the [auditory] cortex suggests that the timing and relative strength of these inputs can affect the activity of the amygdala,” explained Apicella.
Looking forward, the group suggested that further study should focus on understanding the mechanisms of this fear pathway and determining whether its disruption could lead to fear-related conditions such as anxiety, depression and post-traumatic stress disorder, or even neurological conditions such as Alzheimer’s disease.
Sources: Bertero A, Feyen PLC, Zurita H, Apicella A. A non-canonical cortico-amygdala inhibitory loop. J. Neurosci. 39(43), 8424–8438 (2019); www.utsa.edu/today/2019/11/story/brain-amygdala.html