Are Neurons Adapted for Specific Computations? Examples from Temporal Coding in the Auditory System

Are neurons adapted for specific computations? Evolution has led to the appearance of specialized neurons, such as the neurons in the auditory system that encode temporal informationwith great precision (Trussell 1997; Oertel 1999). Nevertheless, it is not clear whether all neurons are adapted for particular computations or even whether specialized computational units are desirable under all circumstances. Some neurons may have more general responses. Other neuron types change their responses under the action of somemodulator, but these might be regarded as being adapted for several computations, rather than for some general input-output function (see Golowasch et al. 1999; Stemmler and Koch 1999; Turrigiano, Abbot, and Marder 1994). It is important to understand the functions of single neurons. Johnston et al (1996) wrote, ‘‘Before one can hope to understand systems of neurons fully, onemust be able to describe the function of the basic unit of the nervous system, that is, the singleneuronand its associated dendritic tree.’’ Tomake the case that neurons may be adapted for particular tasks, we will use the example of temporal coding cells in the vertebrate auditory systembecause their function iswell known. This allows us to tie physiological and morphological observations to function.