Receptive Fields

Abstract

Originally (Hartline 1938) the receptive field (RF) was defined as “the region of the retina which must be illuminated to obtain a response of a given fiber. The location of the receptive field is fixed, its extent however depends upon the intensity and size of the spot of light used to explore it, and upon the condition of adaptation; these factors must, therefore, be specified in identifying it”. A somewhat similar concept was defined earlier (Adrian et al. 1931) but named the receptive area, comprising “the cutaneous area from which a single mechanoreceptor can be stimulated”. Both these receptive field concepts actually describe what is now known as the excitatory RF center. Mechanoreceptive units have only excitatory RF’s, sometimes consisting of multiple excitatory zones distributed on circular or oval areas with well-defined boundaries as in the rapidly adapting and type-I slowly adapting units. More gradually changing sensitivity is found for the RF’s of the Pacinian corpuscles and the type-II slowly adapting mechanoreceptors (e.g., Johansson 1978; Ray and Krüger 1983). Visual RF’s measured for retinal ganglion cells are more complex, they combine an excitatory or inhibitory center with an antagonistic surround. The RF’s are concentric. To encompass this, Kuffler (1953) extended the receptive field concept to “all areas of the receptor surface in functional connection with a ganglion cell”. A still more general definition was given by Sejnowski (1976 a) as “the receptive field of a neuron is the set of sensory receptors which significantly affects its rate of firing”.