Cognitive Enhancement Through Vagus Nerve Stimulation: Methodological Considerations for Behavioral Studies in Rats

Optimal cognition is maintained by a balance of excitatory and inhibitory signaling in brain regions such as the prefrontal cortex and hippocampus. Alterations in excitatory/inhibitory balance are linked to cognitive deficits in aging and a variety of neuropsychiatric disorders. Thus, therapeutic interventions such as electrical vagus nerve stimulation (VNS), which has been shown to modulate excitability and effectively regulate seizure activity in intractable epilepsy, may have benefits for improving cognition. In both humans and rodents, VNS can enhance multiple forms of neuroplasticity and cognition, and recent work from our labs in rats has shown that VNS can reliably enhance cognitive flexibility. In this chapter, we present experimental guidelines and considerations for performing studies of VNS effects on cognition in young and aged rats. Our goal is to provide the reader with examples of specific parameters and methods for conducting such experiments.