FIG. 2.

Higher-order thalamocortical pathways are intact in the modified auditory slice; conventions as in Fig. 1. A and B: focal biocytin injections in the dorsal division of the medial geniculate body (MGd) labels intact fibers that traverse around the lateral geniculate nucleus, thalamic reticular nucleus, and internal capsule, before penetrating into layer 4 of the second auditory area (AII) (B; tracings of labeled axons). Inset in B indicates the horizontal blocking angle for preparing the higher-order auditory slice (see methods). C–E: photostimulation with caged glutamate in MGd (D) results in EPSCs in a layer 4 neuron in AII (C). E: mean EPSC at each stimulation site.