title: Sound exposure accelerates reflex emergence and development in young rats.
abstract: Early sensory experience affects brain development. In rats, most somatic reflexes are not expressed at birth but may take as long as 2 weeks to emerge. Whether sensory enrichment during this early period affects reflex maturation remains unknown. Here, we exposed rat pups to a pure tone (4kHz, 65dB SPL, 8h/day) with their nursing mother during the first 3 postnatal weeks and measured the times when reflexes appeared on the basis of video recordings. Sound exposure accelerated by about 15% the appearance of all reflexes assessed (righting, cliff avoidance, vibrissa placing, negative geotaxis and auditory startle, p<0.001). In addition, sound exposure accelerated the appearance of developmental characteristics: incisor eruption, ear unfolding and eye opening. These changes occurred concomitantly with an increase in pups' body and brain weights, together with a dramatic increase in fluid intake of the nursing mother. These findings are the first evidence that early sound exposure, even before opening of ear canals, accelerates reflex development. We speculate that the observed changes could involve the nursing mother.
authors.affiliation: Department of Anaesthesia, Chi Mei Medical Center (Yong Kang & Loui Ying), Yong Kang City, Tainan, Taiwan.
authors.forename: Edmund Cheung
authors.initials: EC
authors.lastname: So
authors.forename: Ying-Hui
authors.initials: YH
authors.lastname: Chen
authors.forename: Chieh-Yu
authors.initials: CY
authors.lastname: Huang
authors.forename: Jen-Yin
authors.initials: JY
authors.lastname: Chen
authors.forename: Bu-Miin
authors.initials: BM
authors.lastname: Huang
authors.forename: Paul Wai-Fung
authors.initials: PW
authors.lastname: Poon
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D000831:Animals, Newborn; D001307:Auditory Perception; D049628:Body Size; D001835:Body Weight; D001921:Brain / Q000033:anatomy & histology / Q000254:growth & development; D004327:Drinking Behavior; D005247:Feeding Behavior; D005260:Female; D008297:Male; D009929:Organ Size; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex; D014741:Video Recording; D014867:Water
chemical_list: D014867:Water