Neocortical ectopias are associated with attenuated neurophysiological responses to rapidly changing auditory stimuli

Developmental dyslexia has been separately associated with the presence of ectopic collections of neurons in layer I of neocortex (ectopias) and with alterations in processing rapidly changing stimuli. We have used BXSB/MpJ-Y aa mice, some of which have neocortical ectopias, to directly test the hypo thesis that ectopias may alter auditory processing. Auditory event related potentials (AERPs) were elicited by pairs of 10.5 kHz tones separated by si lence, 0.99 kHz, or 5.6 kHz tones of variable duration. Half of the mice te sted had 1-3 ectopias in frontal or parietal cortex, and half had no ectopi as. Mice with ectopias showed a reduced response to the second 10.5 kHz sti muli only when it was preceded by short duration 5.6 kHz tones. These resul ts indicate that BXSB mice are an excellent model for determining how focal neocortical anomalies alter sensory processing. NeuroReport 11:575-579 (C) 2000 Lippincott Williams & Wilkins.