Cell F2 from the midbrain central gray is shown firing during three displays of affective defense (A) and silent during lifting and dropping (D) of cat and pinching of tail (P) which occurred between attack trials 2 and 3. The event marker for affective defense has been adjusted to represent one-second and five-second measures of that behavior. Event markers for all other manipulations in this and succeeding figures correspond directly to the original. The two large excursions in trial 2 and one in trial 3, as well as the small excursions prior to dropping the cat, are movement artifacts. Records in this and succeeding figures were made by playing back from tape recorder at 1/32 original speed into a polygraph with time constant of 0.002 sec. Voltage calibrations on all figures were determined from unfiltered records of same data. Positive deflections are upward.