This work focuses on the role played by certain eliminatory events which occur during the normal development of the cerebral cortex. We have utilized neuroanatomical techniques to study these events and much of our effort has concentrated on the transient visual cortical pyramidal tract which we previously identified. We have also studied the collateral elimination which occurs during the development of the projections of the locus coeruleus. Experiments involving heterotopic cortical transplants have allowed us to identify position within the tangential plane of the cortex as a critical factor in determining which of the initially extended projections, a cortical neuron will maintain. Results of these and other experiments support the notion that certain neocortical cell types are present throughout the tangential plane of the neocortex. Our recent observations with an antibody to a soluble brain protein corroborate this idea.
