Subplate neuron ablation alters neurotrophin expression and ocular dominance column formation

Ocular dominance column formation in visual cortex depends on both the pres ence of subplate neurons and the endogenous expression of neurotrophins, He re we show that deletion of subplate neurons, which supply glutamatergic in puts to visual cortex, leads to a paradoxical increase in brain-derived neu rotrophic factor mRNA in the same region of visual cortex in which ocular d ominance columns are absent. Subplate neuron ablation also increases glutam ic acid decarboxylase-67 levels, indicating an alteration in cortical inhib ition. These observations imply a role for this special class of neurons in modulating activity-dependent competition by regulating levels of neurotro phins and excitability within a developing cortical circuit.