Synaptic Function in the Fish Spinal Cord: Dendritic Integration

Publisher This chapter describes the spinal circuitry involved in the startle response in teleost fish. The achievement of very constant and precise time discrimination depends partly upon the special properties of the first activated synaptic region of the motoneuron. The initiation of the spike is determined by the integration, in this same region, of local synaptic activity. This is expressed as dendritic integration. Dendritic integration, in dendrites that support spikes, provides opportunities for precise timing arrangements that are otherwise achieved only with the less economical provision of large numbers of neurons. The synaptic noise that originates in the main part of the primary motoneuron is attenuated to a negligible level by the time it is conducted electrotonically to the special synaptic region of the junctional branch. The branch is connected to the main part of the dendrite by a relatively high-resistance transitional region that allows electrical excitation in the orthodromic direction (from junctional region to the main part of motoneuron) but possibly not in the reverse direction.