2.4. Behavioral analysis

To monitor activity in a novel environment, an open field apparatus was used, consisting of a square area 76 cm × 76 cm with walls 42 cm high. The floor was divided by lines into 25 equal squares. To determine activity, a rat was placed in the center square of the open field. The numbers of squares crossed with all four paws were scored for 5 minutes.

To monitor activity in a familiar environment, activity boxes were used. The rectangular Perspex activity cage consisted of small square area (26 cm × 26 cm × 26 cm) with sawdust-covered floor. Before monitoring the activity an animal was placed in it for 15 minutes for habituation. Numbers of crossings across the box were monitored for 10 minutes.

Motor coordination was assessed for all rats on a rota-rod. The rota-rod had a 7 cm radius and a speed of 16 revolutions/ minute. Prior to any treatment rats were trained in a single session until they attained 150 seconds on the rota-rod.

Animals were placed individually in an activity box (26 cm × 26 cm × 26 cm) with sawdust-covered floor and were allowed to adapt the observation cage for a period of 15 minutes. VCMs were monitored during a 10-minute observation period. For calculation purposes, each burst of purposeless chewing was counted as one, if its duration was at least 3 seconds.