Cardiac, ventilatory and behavioural arousal responses evoked by electrical brain stimulation in the goldfish (Carassius auratus)

Goldfish (Carassius auratus) were fitted with intracranial stainless steel microelectrodes for electrical evocation of behavioural arousal and its cardiac and ventilatory correlates. Behaviour was monitored on a videosystem and ECG electrodes and a buccal catheter were implanted to monitor physiological responses. Thresholds for responses were described in relation to the current spread likely to excite CNS tissue. Two types of responses were obtained. These were (A) cardiac and ventilatory responses alone, apparently due to stimulation of primary sensory pathways and (B) these responses and behavioural arousal responses which were elicited at higher thresholds. These latter, more complete expressions of arousal resulted from stimulation of the Dm/Dc region of the telencephalon, the dorsal diencephalon and the midbrain tegmentum. Response thresholds were higher and physiological response magnitudes lower in the midbrain tegmentum compared to the forebrain regions.