# Serotonin transporter knockout in rats reduces beta- and gamma-band functional connectivity between the orbitofrontal cortex and amygdala during auditory discrimination

## TL;DR

This study shows that serotonin transporter knockout in rats affects brain connectivity between the orbitofrontal cortex and amygdala during an auditory task.

## Contribution

The study identifies how SERT genotype modulates functional connectivity in specific frequency bands during decision-making.

## Key findings

- SERT−/− rats showed reduced beta- and gamma-band synchronization between the orbitofrontal cortex and amygdala during response selection.
- This reduction was associated with decreased hubness and clustering coefficient in both brain regions.
- Theta synchronization during reward-related behavior was unaffected by SERT genotype.

## Abstract

The orbitofrontal cortex and amygdala collaborate in outcome-guided decision-making through reciprocal projections. While serotonin transporter knockout (SERT−/−) rodents show changes in outcome-guided decision-making, and in orbitofrontal cortex and amygdala neuronal activity, it remains unclear whether SERT genotype modulates orbitofrontal cortex–amygdala synchronization. We trained SERT−/− and SERT+/+ male rats to execute a task requiring to discriminate between two auditory stimuli, one predictive of a reward (CS+) and the other not (CS−), by responding through nose pokes in opposite-side ports. Overall, task acquisition was not influenced by genotype. Next, we simultaneously recorded local field potentials in the orbitofrontal cortex and amygdala of both hemispheres while the rats performed the task. Behaviorally, SERT−/− rats showed a nonsignificant trend for more accurate responses to the CS−. Electrophysiologically, orbitofrontal cortex—amygdala synchronization in the beta and gamma frequency bands during response selection was significantly reduced and associated with decreased hubness and clustering coefficient in both regions in SERT−/− rats compared to SERT+/+ rats. Conversely, theta synchronization at the time of behavioral response in the port associated with reward was similar in both genotypes. Together, our findings reveal the modulation by SERT genotype of the orbitofrontal cortex—amygdala functional connectivity during an auditory discrimination task.