Decline in hippocampal theta activity during cessation of locomotor approach sequences: amplitude leads frequency and relates to instrumental behavior.

Hippocampal theta frequency and amplitude decrease as locomotor approach slows and the goal is reached. This study compared the declines of these theta parameters and related them to behavioral events. Theta activity was recorded with bipolar electrodes spanning cornu Ammon, sector 1 or cornu Ammon, sectors 2/3 cell layers of the dorsal hippocampus in 12 rats trained to approach and depress a treadle which exposed a milk dipper.

Hippocampal theta activity and behavioral sequences in a reward-directed approach locomotor task.

Hippocampal rhythmic slow wave activity (theta) has been implicated in the processing of stimuli associated with movement. This study determined whether the theta rhythm showed phase relationships or changes in amplitude and frequency with the onset of stimuli and behavioral sequences in a skilled locomotor approach task. Rats with bipolar electrodes spanning CA1 approached a stall, turned to enter it, approached and depressed a treadle, waited 1.

Hippocampal theta activity related to elicitation and inhibition of approach locomotion.

This study determined if the hippocampal theta rhythm showed phase relationships or changes in amplitude and frequency with the onset of stimuli and locomotion in a task in which auditory cues initiated and suppressed approach locomotion. Rats with electrodes in the dorsal hippocampus lapped at a milk dipper and were presented a tone which predicted the delivery of a food pellet. In some trials the pellet cue tone was negated by 60-Hz clicks beginning 0.

Brainstem regions with neuronal activity patterns correlated with priming of locomotor stepping in the anesthetized rat.

Locomotor stimulation in the perifornical hypothalamus produces a transient facilitation of subsequent locomotion, a priming effect, such that stepping to a second train of stimulation occurs with a shorter latency of onset and increased amplitude. Neurons responsible for the initiation of this facilitated stepping presumably respond to locomotor stimulation with a similar priming effect, i.e.

Priming pattern determines the correlation between hippocampal theta activity and locomotor stepping elicited by stimulation in anesthetized rats.

The after-effects of locomotor stimulation are a transient facilitation of locomotor initiation (the priming effect), and a transient increase in hippocampal rhythmic slow activity in the 3-6 Hz band of the theta range. The similar time course of the two effects suggests that hippocampal 3-6 Hz activity may be linked to the excitability of locomotor initiation. This study tested the hypothesis that power in the 3-6 Hz band that is present prior to stimulation would predict the magnitude of elicited stepping.