Early lead exposure affects auditory temporal processing in chicks

✍ Scribed by Lincoln Gray; Andrij Holian

• Publisher: John Wiley and Sons
• Year: 1999
• Weight: 106 KB
• Volume: 1
• Category: Article
• ISSN: 1095-1539
• DOI: 10.1002/(sici)1099-1301(199904/06)1:2<87::aid-jem14>3.0.co;2-z

✦ Synopsis

The effects of low-level lead on hearing were investigated in newborn chicks. lead Hearing was measured using an unconditioned response-a delay in subjects' perception ongoing peeping when they detect a new sound. Lead acetate was introduced masking into the air space of the egg at either 12 or 14 days of incubation in doses that thresholds varied between 36 and 88 mg kg ؊1 . Subjects were then tested at 0 and 4 days hearing after hatching. A test of absolute thresholds showed no effect of the lead. A development test of backward masking, however, showed a significant deficit in temporal chickens processing. In backward masking a short tone pip is followed by a brief silent period and then by a longer and louder noise. Ability to hear the brief signal despite the subsequent masker is a test of rapid hearing. Lead-exposed chicks were deficient in this task, especially at 4 days of age and with a brief silent period between signal and masker. Human children with reading disabilities show a similar deficit. It is thus possible that variations of this test can elucidate basic developmental deficits that are also involved in human perceptual disorders and dyslexia.