Spectral modification by operant conditioning of cortical theta suppression in rats

Objective: Brain activity is known to be voluntarily controllable by neurofeedback, a kind of electroencephalographic (EEG) operant conditioning. Although its efficacy in clinical effects has been reported, it is yet to be uncovered whether or how a specific band activity is controllable. Here, we examined EEG spectral profiles along with conditioning training of a specific brain activity, theta band (4-8 Hz) amplitude, in rats. Methods: During training, the experimental group received electrical stimulation to the medial forebrain bundle contingent to suppression of theta activity, while the control group received stimulation non-contingent to its own band activity. Results: In the experimental group, theta activity gradually decreased within the training session, while there was an increase of theta activity in the control group. There was a significant difference in theta activity during the sessions between the two groups. The spectral theta peak, originally located at 7 Hz, shifted further towards higher frequencies in the experimental group. Conclusion: Our results showed that an operant conditioning technique could train rats to control their specific EEG activity indirectly, and it may be used as an animal model for studying how neuronal systems work in human neurofeedback.