Abstract
1. 1. Goldfish ( Carassius auratus) were fitted with ECG electrodes and intra-cranial stainless steel electrodes to monitor cardiac, EEG and SPS responses, during minimal restraint, to presentation of environmental stimuli (light-on, moving shadow, tap). 2. 2. All three stimuli evoked a bradycardia and increases in the EEG frequency; correlates of arousal responses in fish. 3. 3. EEG frequency changes were most evident in the fore- and midbrain regions; in the hindbrain smaller responses nevertheless showed discrimination between stimuli. 4. 4. EEG amplitude changes were more site- and stimulus-specific than frequency changes. 5. 5. SPSs occurred on stimulus presentations which were negative in polarity in the midbrain and positive in the forebrain and hindbrain, though the latter were smaller and less consistent. 6. 6. Principal components analyses and regression analyses were used to examine detailed associations between peripheral and central physiological changes. 7. 7. It was found that increases in the EEG frequency of fore- and midbrain regions were related to cardiac deceleration on early stimulus presentations. 8. 8. This was also shown for the negative SPS of the midbrain to the presentation of the tap stimulus. 9. 9. Positive SPSs of the forebrain were related to the bradycardia on later stimulus presentation i.e. during habituation of the arousal response. 10. 10. The results indicate that in fish, as in other vertebrates, negative SPSs in the midbrain are associated with arousal and implicate the forebrain in the modulation of arousal by its habituation.
Published Version
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