Like most ERP studies using rodents as subjects a “passive” auditory oddball paradigm has been used to generate ERPs in rats. The advantages of a passive paradigm are that it can be administered to human and other animal subjects without extensive prior training, and it does not require the subject to respond to the stimuli. While ERPs have been successfully recorded in a number of animal species the use of ERO technology to study brain function in animal models has been less applied. The present studies extend and confirm our previous findings demonstrating that EROs can be recorded in rodents (Ehlers and Criado, 2009; Criado and Ehlers, 2009). Collapsing across lines, our findings showed that parietal theta and alpha/beta ERO energy was significantly reduced in response to the rare and noise tones, compared to the standard tones. Results from the present study also found that PLI in the parietal delta and theta bands was significantly increased in response to rare and noise tones, compared to the standard tones. These findings suggest that presentation of the standard tone produces an evoked
