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Automated detection and characterisation of rumination in sheep using in vivo electrophysiology.

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Nicol, Alister U 
Perentos, Nicholas 
Martins, Amadeu Q 
Morton, A Jennifer 


Rumination is a precisely timed process that occupies a large part of a sheep's day. The complex motor coordination required to chew and swallow means that quantification of rumination may provide a surrogate marker for effective motor function. Here, data from 24h in vivo electrophysiological recordings, collected as part of an earlier study, were reanalysed for chewing- and swallowing-related activity. The electroencephalographic (EEG) and electromyographic (EMG) data were collected from sheep with surgically-implanted electrodes. An algorithm was designed to detect coordinated, rhythmic muscle activity. This could distinguish episodes of eating from those of rumination. Normal sheep spent ~29% of their time ruminating. Rumination comprised ~40s bouts of regular (~1.7s(-1)) chewing interspersed by ~6.5s intervals during which time no chewing took place. Eating was significantly less regular than rumination, with quicker chewing (~2.7s(-1)). Biomarkers for measuring progression of disease would be invaluable for studying neurodegenerative disease such as Huntington's disease (HD). To test the feasibility of using rumination as such a biomarker, we also made recordings from two neurologically impaired sheep. These showed deviations from the pattern of rumination and eating seen in normal sheep. This validates not only our use of rumination as a measure of normal motor function, but also as a surrogate biomarker for measuring motor dysfunction in impaired sheep.



Dysphagia, Electroencephalogram, Electromyogram, Electrooculogram, Mastication, Algorithms, Animals, Eating, Electroencephalography, Electromyography, Electronic Data Processing, Electrophysiological Phenomena, Sheep, Sleep

Journal Title

Physiol Behav

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Elsevier BV
This work was funded by CHDI Inc. (AJM). Costs in New Zealand relating to the rearing and genotyping of the CLN5 animal from which one of the data sets used here were derived were provided by grants from the Neurological Foundation of NZ and the Batten Disease Support and Research Association (Nadia Mitchell and David Palmer, Dept. of Molecular Biosciences, Faculty of Agricultural and Life Sciences, Lincoln University, Christchurch, New Zealand) and CHDI Inc. (AJM).