"Science Briefs" summarize the findings and implications of a recent study in basic science or clinical research. This Brief reports on the study "Perinatal Exposure to a Noncoplanar Bichlorinated Biphenol Alters Tonotopy, Receptive Fields and Plasticity in the Auditory Cortex" (T. Kenet; R. C. Froemke; C. E. Schreiner; I. N. Pessah; and M. M. Merzenich). The study found that animals exposed to PCBs, an environmental pollutant, had impaired ability to recognize sounds of different frequencies, as well as impaired development of auditory circuits, a key mechanism for learning new skills [Title and Authors: Perinatal exposure to a noncoplanar bichlorinated biphenol alters tonotopy, receptive fields and plasticity in the auditory cortex. Proceedings of the National Academy of Science, USA 104:7646-7651. Kenet, T., Froemke, R.C., Schreiner, C.E., Pessah, I.N. and Merzenich, M.M.]