EN
The development of the central auditory system is an activitydependent process. Hence, any manipulation of the hearing organ that temporarily alters the input to the central auditory nuclei can have a serious and mostly permanent impact on their structure and function. Our previous study showed that adult rats exposed to intense brief noise as juvenile had signifi cantly deteriorated frequency selectivity of the inferior colliculus neurons. In this study, we focused on sound level processing in inferior colliculus neurons in rats exposed for 8 min to intense broad-band noise on postnatal day 14. At the age of 3–6 months, the neuronal activity in the central nucleus of the inferior colliculus was recorded under ketamine-xylazine anaesthesia, and the parameters of the rate-level functions were compared between the neurons of noisetreated rats (n=116) and age-matched controls (n=94). While the neuronal thresholds in the two groups did not differ signifi cantly, the neurons of the exposed animals exhibited a signifi cantly short er dynamic range and a steeper slope of the rate-level function compared with controls. The results indicate that a short-lasting exposure to intense sound during the sensitive period of postnatal development disrupts the normal coding of sound intensity in the inferior colliculus neurons. Supported by grants AV0Z50390512, GACR 309/07/1336, GACR 309/08/H079, IGA NR 8113-4 and LC 554.