As Novel Sights Become Familiar, High Frequency Brain Rhythms Transition to Lower Frequency Brain Rhythms

Article: As novel sights become familiar, different brain rhythms, neurons take over
Source: Picower Institute for Learning and Memory at MIT, via NEI
Published: June 9, 2021

High frequency gamma oscillation was higher for novel images
and low frequency beta oscillation was higher for familiar images

Attending to novel stimuli in one's environment is a behavioral response that benefits survival. However, once you learn that the novel stimulus is nothing of significance, it is equally adaptive to no longer pay attention to it. Thus, determining whether a stimulus is novel or not is integral to normal brain function. Dubbed "visual cognition memory," the researchers used a mouse model to study how stimulus selective response plasticity (SRP) correlated with habituation, the behavioral loss of interest in exploring an increasingly familiar stimulus. Their research showed that long-term potentiation (LTP), a strengthening of neural connections amid frequent activity, is involved but does not fully explain visual cognition memory. Inhibitory neurons called parvalbumin (PV) expressing neurons, which produce high frequency gamma rhythms in the cortex, also seem to be involved. As novel visual stimuli become familiar, the gamma rhythms of these PV neurons give way to lower frequency beta rhythms by inhibitory somatostatin (SOM) expressing neurons. The experiments involved engineered mice whose PV or SOM neurons would flash brightly when active, and could be detected with two-photon microscopy. These mice were shown the same grating patterns over several days (including challenge trials) as researchers measured changes in their neuronal activity. This brain rhythm shift provides an externally measurable indicator of the transition from the novel to the familiar. The senior author further explains, "It also offers a new hypothesis for how visual recognition memory is enforced: PV activity, which initially inhibits the SRP electrical response, eventually itself becomes inhibited by SOM activity." The researchers next plan to use optogenetics to manipulate SOM neurons to further test the hypothesis that SOM neurons inhibit PV neurons in the perception of stimuli as novel versus familiar. They also intend to explore whether this neural frequency transition could be used as a biomarker for autism spectrum disorders.

Additional note : The project lead was also recently awarded for amblyopia research.

My rating of this study: ⭐⭐⭐

Hayden DJ, Montgomery DP, Cooke SF, et al. "Visual recognition is heralded by shifts in local field potential oscillations and inhibitory networks in primary visual cortex." Journal of Neuroscience.  JN-RM-0391-21. 8 June 2021. https://doi.org/10.1523/JNEUROSCI.0391-21.2021