title: Head-cocking as a form of exploration in the common marmoset and its development.
abstract: Head-cocking of 15 infant marmosets (Callithrix jacchus) was scored from Day 1 to 60 of postnatal life, the growth period with overproduction of interneuronal synapses. Head-cocking was scored during four 30 min intervals daily, including angle of head-cocking and objects being fixated. Mean age of onset of head-cocking was Day 13 (+/-1.3) and frequency increased to a fixed rate by Day 24-29, at the time of maturation of the foveal representation in layer 6 of the visual cortex, thus lending further support to the importance of head-cocking to visual processing. The most common distance of objects fixated during head-cocking was up to .5 m. Angle of head-cocking increased with age, and some asymmetry of direction was noted. Fewer head-cocking events occurred in the morning than in the afternoon. We also scored anogenital licking of offspring. Head-cocking occurred at higher levels in marmosets receiving more anogenital licking. As this was associated positively with increased exploration, head-cocking may be regarded as an exploratory behavior.
authors.affiliation: Centre for Neuroscience and Animal Behaviour, University of New England, Armidale, NSW-2351, Australia. gkaplan@une.edu.au
authors.forename: Gisela
authors.initials: G
authors.lastname: Kaplan
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Rogers
mesh_terms: D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal; D002144:Callithrix; D005106:Exploratory Behavior; D005403:Fixation, Ocular; D006120:Grooming / Q000502:physiology; D019416:Head Movements; D008425:Maternal Behavior