behavior/neurological
• when suspended by the tail, mice are very active, bobbing up and down and flexing the head and trunk ventrally
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• mice, aged 6 weeks and older, spend 1480 seconds/hour in non-stereotypic behavior compared to 576 sec/hour in littermated controls; phenotype is apparent around 3 weeks of age
• hyperactive behavior is significantly different from control strains and wild-derived strains which spent between 325 and 876 seconds/hour in ambulation
• distance covered in a 1 hour period is 409 meters, significantly different from heterozygous littermates and inbred strain controls
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• mice perform (mean values) 397 clockwise (CR) and 478 counterclockwise (CCR) rotations per hour compared to 50 CR and 45 CCR in heterozygotes
• circling behavior is similar to other waltzing mutants
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hearing/vestibular/ear
• aberrant structure forms at the apex of cochlea by E15.5
• at P21, apical turn of cochlea is absent
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• growth of cochlear duct appears to arrest at E13.5; truncation is more pronounced at E15.5
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• auditory brainstem responses (ABR) measurements show that mutants only respond at high sound pressure levels only
• mice do not show progressive hearing loss; auditory threshold is not age-dependent
• Background Sensitivity: auditory threshold is significantly increased compared to mutants on mixed backgrounds
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• mice have no measurable distortion-product otoacoustic emissions (DPOAEs) at 3 primary-tone levels while heterozygotes fall in normal range for all levels
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• VESPs are absent at the maximum stimulus intensity used
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