There were two aims of this study:
1) to compare the EEG changes caused by cutaneous application of noxious thermal (52°C water bath), mechanical (forceps clamp 20 N), and electrical stimuli (50 V, 50 Hz for 2 s).
2) to identify the most promising modality of noxious stimulation that could be applied to future studies investigating EEG changes during the application of a cutaneous phasic acute pain stimulus.
The authors hypothesized that the stimuli investigated would cause quantitatively different EEG responses, because the perception of pain associated with each stimulus is qualitatively different. Thermal, mechanical, or electrical noxious stimuli are frequently applied in studies investigating EEG responses to noxious stimulation in animals, and these models have been used to investigate modulation of these responses by co-administration of different drugs.
48 (anesthetized) rats were divided into three groups (each group one stimulus).
Exposure duration: 2 seconds
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Different noxious stimuli caused differing EEG alterations. Therefore, extrapolation of data between EEG studies using different modalities should be avoided. The variable EEG response to the mechanical and thermal stimuli suggests that these are unsuitable stimuli to investigate EEG responses to noxious stimulation in anaesthetized rats.