Theta-like rhythm in depth EEG activity of hypothalamic areas during spontaneous or electrically induced locomotion in the rat.

Spontaneous locomotion performed by an awake rat is accompanied by synchronized activity (a theta rhythm) of the hippocampus (Hipp). Locomotion can also be induced by electrical stimulation of various sites within the brain. The effectiveness of electrical stimulation of the subthalamic locomotor region (SLR) and posterior hypothalamus (PH) in inducing locomotor movements has previously shown that they are parts of the system controlling locomotion. Thus, it was of interest to determine whether their electrical activity was correlated with the motor behavior, as it is in the Hipp. The experiments done here on chronic animals with electrodes implanted into the Hipp and hypothalamus showed that rhythmic depth EEG activity (theta-like) similar to that found in the Hipp is present in motor-positive hypothalamic areas during spontaneous locomotion. In addition, our results showed that movements induced by stimulation of various hypothalamic sites are also accompanied by theta-like activity in the Hipp and some hypothalamic areas. Thus, our results support the idea that the well-known and anatomically established connections between the Hipp and hypothalamus are active during locomotion. These connections may constitute a part of the system involved in the control of the motor behavior.