Indeed, several molecules and signaling pathways

recently shown to be involved in visual map development were initially identified through differential screens for genes regulated by neuronal activity (e.g., Shatz, 2009). The results described here show that even rather subtle genetic manipulations that only alter patterns of spontaneous activity without changing the levels of activity can have a profound impact on brain development. This may have significant implications for diseases check details of multigenetic origin, such as schizophrenia and autism, in which brain wiring may be negatively affected not because of direct effects of genes on neural circuits or synaptic function, but because of indirect effects on patterns of spontaneous or evoked activity during neural circuit development. β2-nAChR subunit knockout β2(KO) and transgenic β2(TG) mice with retina-specific expression of β2-nAChRs were generated as described (King et al., 2003). Wild-type (WT) mice (C57BL/6J) were

obtained from Jackson Laboratory (Bar Harbor, ME). Doxycycline administration was provided through the mothers of experimental Afatinib clinical trial mice via water containing doxycycline (1mg/ml) from E0 to P8. Animals were treated in compliance with the Yale IACUC, U.S. Department of Health and Human Services, and Institution guidelines. Focal DiI injections (2.3 nl) for measurements of retinotopy were performed,

imaged and quantified blind to genotype as described (Chandrasekaran et al., 2005). Injections were localized along the perimeter of the retina, using as a reference the insertion points of the four major eye muscles (Plas et al., 2005). Retinal injection size, quantified by measuring the area of fluorescent signal in the retina above one-half of the maximum fluorescent signal after background subtraction, showed no difference across all genotypes and injection locations, and there was no relationship between TZ area and retinal injection area (Figure S7; McLaughlin et al., 2003). Measurements of eye-specific segregation were performed with whole eye injections (1 μl into the vitreous) of Alexa Fluor 488-conjugated cholera toxin (left eye) and Alexa Fluor 594 (right eye) at P6, then returned to their mother for 24–48 hr crotamiton to allow transport of tracer from the retina to the SC and dLGN. CPT-cAMP treated animals were injected daily with 500 nl of saline or CPT-cAMP (5 mM) into both eyes from P2 to P6, then received whole eye injections of Alexa dye at P7. Eye-specific segregation in the SC was quantified by measuring the fraction of fluorescence signal labeled from the ipsilateral eye in the SGS layer, and also by measuring the overlap (in % of pixels) of ipsilateral eye fluorescence signal with contralateral eye fluorescence signal in the SGS layer.