Neuronal activity in behaving rodents during spontaneous social behavior:

Oscillatory brain activity, mostly categorized to the theta (4-10 Hz), beta (10-30 Hz) and gamma (30-80 Hz) bands, is thought to coordinate activity in vast neuronal assemblies dispersed over different brain regions. This type of coordination may underlie high level cognitive functions, such as speech and social communication, which are impaired in ASD. Indeed, accumulating evidence suggest that subjects with ASD show deficits in long range neuronal communication associated with low-frequency rhythms, such as the theta rhythm. A connection between rhythmic brain activity and social behavior has not yet been demonstrated. We use wireless chronic recordings from socially behaving rats to monitor rhythmic neuronal activity in a network of limbic brain regions linked to social behavior, including the AOB, MOB, medial amygdala, lateral septum and piriform cortex. We found that social encounters are associated with enhancement of brain theta rhythmicity in a manner that is positively proportional to the degree of novelty of the social stimulus. This modulation of theta rhythmicity, which is specific for social stimuli, is not due to changes in investigation behavior. Instead, it reflects an internal brain state associated with social arousal. We plan to expand these experiments to other paradigms and brain areas.