title: Early experience and domestication affect auditory discrimination learning, open field behaviour and brain size in wild Mongolian gerbils and domesticated laboratory gerbils (Meriones unguiculatus forma domestica).
abstract: The influence of early experience and strain differences on auditory discrimination learning, open field behaviour and brain size was investigated in wild-type Mongolian gerbils (strain Ugoe:MU95) raised in the wild (wild F-0) or in the laboratory (wild F-1) and in domesticated Laboratory Gerbils (LAB). Adult males were conditioned for 10 days in a shuttle box go/no-go paradigm to discriminate two frequency-modulated tones. Significant learning was established within 5 days in wild F-0 and within 3 days in wild F-1 and LAB. Spontaneous jumps in the shuttle box (inter-trial crossings) were frequently seen in wild F-0 and F-1, but rarely in LAB. All groups exhibited nearly the same ability to remember after 2 weeks without training. In the open field test applied on 5 consecutive days, no differences in locomotion patterns and inner field preferences were found. Rearing frequency decreased over 5 days in wild gerbils. Running distances (4-6m/min) were similar in wild F-0 and LAB, but higher in wild F-1. The ratio of brain size to body weight did not differ between wild F-0 and F-1, but was 17.1% lower in LAB. Correspondingly high brain weights in wild F-1 and F-0 support our domestication hypothesis and negate any serious effect of early experience or captivity on brain size in Mongolian gerbils. In contrast, wild F-1 raised in the laboratory show a rapid improvement in learning performance, indicating that early experience rather that genetic differences between strains affect shuttle box discrimination learning in gerbils.
authors.affiliation: Georg-August-University of Goettingen, Department of Phoniatrics and Pedaudiology, Sensory Developmental and Voice Research Group, Robert-Koch-Str. 40, D-37075 Goettingen, Germany. stuermer@med.uni-goettingen.de
authors.forename: Ingo W
authors.initials: IW
authors.lastname: Stuermer
authors.forename: Wolfram
authors.initials: W
authors.lastname: Wetzel
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D000830:Animals, Laboratory; D000835:Animals, Wild; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000033:anatomy & histology*; D004193:Discrimination Learning / Q000502:physiology*; D004777:Environment; D005106:Exploratory Behavior / Q000502:physiology*; D005849:Gerbillinae / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D011939:Mental Recall / Q000502:physiology; D009929:Organ Size; D013045:Species Specificity