Behind your eyes several regions of your brain are devoted to processing the information the retinas send their way. Discoveries in the lab of Picower Professor Mark Bear have shown that the visual cortex is not just sorting out shapes, colors and motion, but is even capable of storing and acting on simple forms of memory that affect behavior.

The type of “visual recognition memory” his lab characterized is fundamental to human behavior. It helps us account for (and ignore) what we’ve already seen so that we are better able to focus on what’s new. Notably, this kind of memory appears to be disrupted in conditions like autism and schizophrenia.

In 2003 Bear Lab graduate student Nate Sawtell (now a professor at Columbia) was trying to assay visual responses in the visual cortex of mice (V1) when he observed something surprising. Mice shown the same visual pattern every day produced a steadily increasing electrophysiological response. Novel patterns reset the response at the initial baseline level. The lab called this phenomenon “stimulus-selective response potentiation” or SRP and in 2010 they reported evidence that it is produced by a common memory-making molecular mechanism called long-term potentiation.

Above: A blue coronal mouse brain section shows green highlighting in the visual cortex

In a paper in 2015, the lab showed how SRP reveals the basis of visual recognition memory. Mice are so excited by new visual patterns they will try to explore them but this behavior diminishes, or habituates, over days as a pattern becomes familiar and SRP emerges in V1. Bear’s team showed in V1 that by blocking various synaptic processes and receptors – the same protocols that can be used to disrupt SRP – they could prevent that habituation. The ability the mice developed to recognize and ignore innocuous familiar stimuli was based their visual cortex using SRP to form a visual recognition memory.

In 2021 the lab went on to report that the emergence of SRP takes hold with significant shifts in brain activity. Gamma brain waves give way to lower frequency beta waves (and the activity of PV neurons dies out in favor of a rise in activity by inhibitory somatostatin expressing neurons). Because the study provides an externally measurable indicator of the transition from novel to familiar—the brain wave shift—the findings could provide a test for disorders in which visual recognition memory is reduced.