Dendritic anatomy and electrotonic transfer properties of cat superior colliculus neurons

Detailed morphometrical and corresponding electrotonic characteristics on three classes of cat superior colliculus (SC) neurons have been derived. The sample of cells selected for analysis comprised ascending projection neurons (APNs), inter-layer neurons (ILNs) and tecto-reticulo-spinal neurons (TRSNs) recorded intracellularly and stained with HRP. Superficial SC neurons (APNs, ILNs) could be attached to the allo- and idiodendritic type while deep layer neurons (TRSNs) belong to the isodendritic type. For each neuron, the branching pattern, lengths and diameters of the dendritic trees were determined. These data served as input to the computer program "DENDRIT" from which electrotonic membrane and transfer properties were calculated. Both the morphometrical data and the electronic properties underline the contrasting features of superficial vs deep layer neurons in the SC. Our results support the hypothesis that on the neuron level a close relationship between dendritic pattern and neuron function might exist.