A study from Cedars-Sinai Health Sciences University reports that activity in particular neurons in the amygdala can predict whether a newly viewed image will later be remembered. The findings, published in Nature Neuroscience, broaden the picture of a brain region most often associated with emotional and social behavior.
The amygdala is a small structure located deep in the temporal lobe. Its role in memory has traditionally been linked most closely to experiences involving fear or other strong emotion. The new work instead points to a wider role: helping determine which ordinary, novel experiences are selected for long-term storage.
A filter for lasting experiences
The researchers describe the amygdala as acting like a filter that tags a small subset of ongoing experiences. Those tagged experiences are then available for later retrieval as long-term memories.
According to Ueli Rutishauser, director of the Center for Neural Science and Medicine at Cedars-Sinai and the study’s corresponding author, the activity of specific amygdala neuron types predicted, while a person was seeing an image for the first time, whether that image would later be remembered.
The kind of memory at issue is episodic autobiographical memory: recollections connected to the events of everyday life, such as where someone parked a car or how they spent a recent family vacation. These memories support day-to-day navigation and contribute to a person’s sense of identity.
Category-selective neurons
The study identified neurons in the amygdala that responded selectively to categories of images, including faces, animals and landscapes. These category neurons were not simply responding to the fact that an image was new. Their level of activity was related to a later memory outcome.
When a category neuron responded more strongly as a participant viewed an image from the category to which that cell was tuned, the participant was better able to recall that image later. In that sense, the neural signal observed at first viewing carried information about whether an experience was likely to persist.
The result does not mean every image is stored, or that the amygdala alone creates memories. Rather, it supports the idea that the region helps mark a limited portion of what people encounter for long-term retention. That framing is important because people are continuously exposed to far more information than they can later recall.
Rare recordings in people
The evidence came from recordings of single-neuron activity in 112 surgical patients. The participants had electrodes implanted in their brains for clinical monitoring of epileptic seizures, allowing investigators to record neural activity while people took part in memory tasks.
Participants were shown images, and the researchers assessed later recall. The approach let the team compare the firing of individual neurons at the moment an image was first seen with whether that same image was later remembered.
Single-neuron recordings in human participants offer a direct view of brain activity that cannot be obtained through broad measures alone. Here, they enabled the researchers to distinguish the responses of specific amygdala cells and relate those responses to memory performance.
What the finding could mean
The work suggests that the amygdala’s contribution to memory is not restricted to highly emotional events. Specific neurons may help identify novel experiences that are worth retaining, even when the material does not appear to be defined by fear or another strong feeling.
That distinction could matter for efforts to understand memory disorders. Cedars-Sinai said the discovery points to the amygdala as a potential target for treating such conditions. The study itself establishes an association between neural activity and later recall; it does not establish a treatment or show that altering the neurons improves memory.
Further research will be needed to determine how these signals interact with other memory-related brain systems and whether they can be safely used to guide clinical approaches. For now, the study supplies evidence that the amygdala contains neurons whose responses can forecast which new images are likely to become part of a person’s longer-term record.
This article is based on reporting by Medical Xpress. Read the original article.
Originally published on medicalxpress.com
