Figure 6.

The general higher immobility levels under RE inactivation during conditioning and test could be partially attributed to the lower locomotor activity, but not changes in shock sensitivity or innate anxiety state. The locomotor activity and sleeping state of RE_VEH-NoCOND_SAL and RE_MUS-NoCOND_SAL groups during the BL and the 10 ISIs in conditioning session were analyzed. Three control experiments were conducted using these 2 groups of animals after the conclusion of trace conditioning and retrieval. The drug history of the animals during conditioning, as well as the order of the EPM and marble burying test, was counterbalanced. (A) The locomotor activity levels of RE_VEH-NoCOND_SAL group were significantly higher than RE_MUS-NoCOND_SAL group. (B) The time the animals spent in sleep was marginally higher in the RE_MUS-NoCOND_SAL group than the RE_VEH-NoCOND_SAL group. No statistical differences were found between the control and the RE inactivation group in (C) the magnitude of the footshock eliciting any reaction in shock sensitivity test, (D) the percentage of entries into open arms in EPM (left), or (E) the number of buried marbles in the marble burying test. RE inactivation group showed a trend of spending more time in the open arms compared to the control group (right of D; +, .05 ≤ P < .1). BL, baseline; EPM, elevated plus maze; ISIs, interstimulus intervals; RE, nucleus reuniens; VH, ventral hippocampus.