In the prefrontal cortex, apical dendrites of pyramidal neurons receive parallel input from other parts of the neocortex, whereas the basilar dendrites of Layer III neurons are primarily innervated by reciprocal connections from the mediodorsal and anterior nuclei in the thalamus (Heidbreder & Groenewegen, 2003; Rotaru et al., 2005; Wedzony et al., 2005). Reciprocal connections from the mediodorsal nucleus are directed to Layer III, whereas cortical projections to the mediodorsal nucleus originate from Layer VI (Heidbreder & Groenewegen, 2003). Inputs from the mediodorsal nucleus not only synapse directly onto the spines of pyramidal cells in the mPFC but they also have an indirect influence through the local cortical interneurons; in particular paravalbumin (PV) cells (Rotaru et al., 2005). These inhibitory cells synapse primarily onto the soma, proximal dendrites and axon initial segments of PFC cells. Still, not only do the majority of excitatory mediodorsal neuron axons innervate the basilar dendritic spines of Layer III PFC pyramidal cells (2005) but excitatory projections from the anterior thalamic nuclei also form synaptic contacts on the basilar dendrites of Layer III pyramidal cells (Shibata,
