Abstract
The prefrontal cortex (PC), hippocampus (HP) or amygdala (AM) reportedly control locomotor activity, which is an essential index of the standardized animal test for several neurotoxicity studies. To investigate the relationship between the brain regions/pathways and locomotor control, we compared the effects of bilateral and crossed unilateral lesions induced by ibotenic acid on locomotor and rearing activities, and studied the effect of repetitive measurement at a 24-h interval by applying footshock (below 0.3 mA, reportedly insufficient to condition fear) at the first measurement. In an open-field cage (45 cm square) equipped with shock grids, all the sham-operated groups gradually decreased their locomotor or rearing counts to 30% during the first measurement for 1 h. During the second measurement, each curve was consistently lower than the initial version. Remarkably, HP-AM disconnection increased the initial curves for locomotor and rearing activities to about 200 and 400% of the sham group but not to the extent of the second ones. We will report on other lesion effects on locomotor and rearing activities and discuss the relationship among these brain regions/pathways, locomotor/rearing control, and learning/memory/emotion. [Jpn J Physiol 55 Suppl:S182 (2005)]
