Figure 3.

Maternally directed orienting behaviors in P0 pups. A, For video monitoring, pups were placed in a Plexiglas corral in the middle tier of a nest temperature-controlled three-tiered chamber, first alone (the control condition; data not shown) and then under the anesthetized dam placed in the upper tier (test condition; as illustrated). A mirror was placed below the pup in the bottom tier at a 45° angle to provide a simultaneous ventrum-angle view of the pup; a microphone was mounted on the right side of the corral to record barking (adapted from Polan et al., 2002). For each litter, pups were monitored sequentially for 4 min under the control condition (open bars in subsequent graphs) and then for 4 min under the test condition with an anesthetized dam (filled bars in subsequent graphs). B1–B3, Pups were scored for the time they spent prone (B1), on their side (B2), or supine (B3). Wild-type mice responded to the introduction of the dam by rotating to the supine position (B3), whereas nulls showed no significant response (p values for effects of genotype, test condition, and their interaction were all <0.01). Nulls spent more time on their side than wild types and heterozygotes (p < 0.05). C, Mean number of total awake behaviors was scored. There were no overall genotypic differences in activity counts. Awake behaviors included dorsal/ventral turning; limb, torso, or head movement; mouth/lick; bark; and locomotion. D, Nulls rarely barked or locomoted, either when they were alone or with the dam (genotype effect, p < 0.1 and p < 0.05, respectively; test condition effect, p < 0.01). Nulls mouthed and licked excessively (p < 0.01). Error bars represent SEM.