EEG and ERP recordings were collected in one recording session in a sound-attenuated and electrically grounded BRS/LVE recording chamber (90 × 90 × 85 cm). The auditory ERP session consisted of 312 individual tone presentations or trials. A three-tone auditory ‘oddball’ paradigm that has been developed to directly model studies employed in humans was used (Putnam and Roth, 1990, Kaneko et al., 1996). Three tone types were presented: a standard tone (1000 Hz square wave, 70 dB, 84% probability), a rare tone (2000 Hz square wave, 85 dB, 10% probability), and a noise tone (white noise, 100 dB, 6% probability). For study 2, the standard tone generated was 75 dB. All tones were presented for 20 ms with rise and fall times of < 1 ms. Individual trials were 1000 ms in duration (100 ms pre-stimulus + 900 ms post-stimulus) and were separated by variable intervals ranging from 500 to 1000 ms. At the conclusion of the testing, all mice were euthanized using CO2 asphyxiation. Further details about the auditory ERP sessions were described previously (Ehlers and Somes, 2002: Slawecki et al., 2003).
