Visual sensory-motor gating by serotonin activation in the medial prefrontal and occipital, but not in the rhinal, cortices in rats.

A behavioral reaction to sensory stimulation is a basic mechanism which is pivotal to many complex behavioral responses. In previous studies we found that visual stimulation induces a selective serotonergic and dopaminergic activation in the occipital (OccC), but not temporal (TempC) cortex in freely moving rats. In a behavioral study in rats we demonstrate now that visual stimulation (0, 8, 22, 82, 155 or 440 lux) activates behavioral activity in an intensity-dependent manner. Behavior activating visual stimulation with 82 lux, but not 22 lux or 82 dB white noise, increased extracellular serotonin (5-HT), but not dopamine (DA), in the medial prefrontal cortex (mPFC) in freely moving animals measured by in vivo microdialysis. There was no effect on 5-HT or DA in the entorhinal and perirhinal cortex. Visual stimulation with 82 lux increased extracellular 5-HT in the mPFC and OccC also in anesthetized animals, but had no effect in the TempC. Auditory stimulation reduced 5-HT in the TempC, but had no effect in the mPFC or OccC. Neither visual nor auditory stimulation had a significant effect on DA in all three cortical areas. We conclude that visual stimulation induces behavioral activation by increasing 5-HT activity in the mPFC and OccC.