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ThesisItem Open Access Electroencephalographic responses to somato-sensory and visual stimuli in goats(G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand), 2009-01) Madan, Arun Kumar; Rastogi, S.K.EEG can serve as an index of mental state, which can be particularly useful for studies in animals, where mental states are much less accessible for objective study as in humans. Changes in EEG variables can be considered as reliable indicators of pain perception and visual assessment utilized for providing important diagnostic information. Keeping this in view the study was undertaken to develop a suitable montage under multiple electrode system in goats and utilizing it for possibility of pain assessment and perception area of brain through EEG. Fifteen heads of local X Jamunapari goats of about 2 years of age were fixed in 10% formalin-phenol solution and a mathematical relationship was developed between the underlying brain structures and surface points on the skull so that the electrode placement sites could be standardized. The findings were corroborated radiologically in live animals also. Seven goats were trained to experimental conditions and a seven channel monopolar montage was used for assessment of various somatic and visual stimuli. The somatic stimulations provided were skin brushing, intravenous, intramuscular and subcutaneous injection with 18G and 20 G needles. In addition intradermal injection with 24 G needle was given. All the injections had NSS as injection material. The visual stimuli were blind folding with the help of cloth, lights off, lights off with photic stimuli at 2 Hz, 11Hz and 15 Hz. Visual stimuli was also provided with photic stimulations at 2 Hz, 5 Hz, 11 Hz, 13Hz and 15 Hz with lights on. After the EEG traces were screened for interference, three records of 3 seconds of qEEG was utilized for spectral analysis through FFT to raise Total Power, Spectral Edge Frequency, Median Frequency and Peak Power Frequency over entire spectrum and Relative Power over four bandwidths. The data was analyzed by ANOVA to statistical difference between different electrodes. The parietal and vertex areas of right side brain were identified as most active during the resting phase in goats. The somatic stimuli like skin brushing and intravenous injections were assessed on the contralateral side of the brain in the parietal electrode regions. These regions of the electrodes overlie the primary and secondary somatic areas of the brain. The intramuscular injections induced higher bioelectric activity in the parietal cortex but the extent of activation of ipsilateral or contralateral somato-sensory areas were variable and non-specific. The subcutaneous and intradermal injections were given on the back of the animals in lumbar region and in their case clear cut contralateral assessment could not be made, possible due to less representation of trunk in sensory cortex of ruminants or some ipsilateral projections from thalamic nuclei. The visual stimuli like blind folding was not able to provide a clear cut description of visual assessment in brain cortex however, other stimulations produced changes in right occipital with closely followed by left occipital regions with passage of stimulus from frontal to occipital through vertex region of brain in both, the light adapted and dark adapted goats.
