Fearful memories from the past may be stored in the sensory cortex, and not the amygdala. The corresponding study was published in Current Biology.
The amygdala, a small almond-shaped structure in the center of the brain, has long been known as the brain’s ‘fear center’, responsible for processing and responding to perceived threats.
However, in recent years, evidence has been emerging suggesting that the sensory cortex- all cortical areas linked to sensory function such as seeing, hearing, etc.- may be implicated in threat processing and long-term threat memory. However, a lack of mechanistic insights has obscured a direct linkage until now.
In the present study, researchers assessed human olfactory threat conditioning and long-term threat memory. To do so, they exposed individuals to neutral smells alongside disgusting images and sounds, and assessed their responses via fMRI.
They found that the human sensory cortex- in this case that for smelling- stores memories from frightening events in the past. They noted associative plasticity in the olfactory cortex, including immediate and lasting pattern differentiation between conditioned and unconditioned stimuli.
The researchers write that their findings show the mechanisms underlying the sensory cortex are key components of threat circuitry. As this system appears to be hyper-functioning in anxiety, they further say that their findings contribute to theories suggesting an exaggerated sensory cortical representation of threats in anxiety.
“We were hoping to find neural evidence supporting long-term threat memory in the olfactory cortex at the outset of this research,” said Yuqi You, one of the study’s authors and Research Assistant at Florida State University. “What surprised me was that long-term threat memory in the olfactory cortex could take many forms, and these different neural mechanisms were all consistently hyperfunctioning in anxiety.”
“This research reveals mechanistic insight into how threat memory forms and is stored in our sensory cortex. Knowing that this sensory-based threat memory is hyperactive in anxiety takes us a step closer to helping people with anxiety disorders change their maladaptive threat perception and memory,” she added.