Hole-Board Test for Spatial Novelty Recognition

The HB test has been shown to involve the dorsal hippocampus and utilized to test the ability of rats to recognize environmental spatial novelty (Lemon and Manahan-Vaughan, 2006 (link); Costa et al., 2012 (link)). The recording chamber measured 40 × 40 × 40 cm was made of opaque gray Plexiglas. A hole-board (39.8 × 39.8 × 5 cm) was inserted into the floor of the recording chamber before the test. Each corner of the hole-board contained a hole, 5.5 cm in diameter and 5 cm deep. On the other side, there were no holes. Dim illumination was provided by a white bulb (120 Lx) suspended 1.2 m above the apparatus. On the day before the first trial, the home cages were transferred to experiment room till the end and rats were allowed to explore the hole-board without holes for 10 min for habituation. After 24 h, a hole-board (39.8 × 39.8 × 5 cm) was inserted into the floor of the recording chamber. Each corner of the hole-board contained a hole. Then the rats were allowed to explore the hole-board for 10 min (first trial), and the number of holes nose-poke was counted. After 2 h, the same experimental context was maintained and the animals were allowed to re-explore the hole-board for 10 min (second trial) and the number of holes nose-poke was counted. To ensure that no odor cues were available, the recording chamber and hole-board were wiped with 20% alcohol after each trial. A reduction of head-dippings into the holes in the second trial indicates better recognition of novel context feature. For evaluating the dose and time dependent effects of iTBS on the HB performance, the first trial of the HB test started 30 or 80 min after real or sham-iTBS (n = 8 rats/group).