Running head : The EEG changes during wheel and treadmill running Voluntary and Involuntary Running in the Rat Show Different 1 Patterns of Theta Rhythm , Physical Activity and Heart Rate

20 Involuntary exercising rats undergo more physical and mental stress than voluntary exercising 21 rats; however these findings still lack electrophysiological evidence. Many studies have reported 22 that theta rhythm appears when there is mental stress and that it is affected by emotional status. 23 Thus, we hypothesized that the differences between voluntary and involuntary movement should 24 also exist in the hippocampal theta rhythm. Using the wheel and treadmill exercise models as 25 voluntary and involuntary exercise models, respectively, this study wirelessly recorded the 26 hippocampal electroencephalogram, electrocardiogram, and three dimensional accelerations of 27 male young rats. Treadmill and wheel exercise produce different theta patterns in the rats before 28 and during running. Even though the waking baselines for the two exercise types were recorded 29 in different environments, there do not exist any significant difference after distinguishing their 30 sleep/wake status. When the same movement related parameters are considered, the treadmill 31 running group showed more changes in their theta frequency (4-12 Hz), in their theta power 32 between 9.5-12 Hz, and in their heart rate than the wheel running group. A positive correlation 33 between the changes in high frequency (9.5-12 Hz) theta power and heart rate was identified. 34 Our results reveal various voluntary and involuntary changes in hippocampal theta rhythm as 35 well as divergences in heart rate and high frequency theta activity that may represent the effects 36 of an additional emotional state or the sensory interaction during involuntary running by rats. 37 38 39