Receptive field tuning properties define the functions of visual areas

The receptive field (RF) of a neuron in visual cortex is the part of the visual field from which action potential responses can be elicited by presenting a stimulus. This stimulus has to meet a number of requirements for the cell to respond; that is, the RF is “tuned” to particular features. For example, cells in primary visual cortex (V1) respond better to some orientations of luminance contrast than to others (Hubel and Wiesel, 1968, 1977). Traditionally, the function of a visual area is derived from the set of features to which the neurons in the area are tuned. MT is called a motion area because many of its cells are tuned to direction, speed, or other aspects of motion (Allman et al., 1985a; Maunsell and Newsome, 1987; Maunsell and Van Essen, 1983; Movshon et al., 1986; Newsome et al., 1986); V4 is a color or form area because cells are tuned to certain wavelengths (Zeki, 1973, 1980) or elementary shapes (Desimone and Schein, 1987; Gallant et al., 1996); and so on. This view is further corroborated by the fact that lesions in these areas typically cause deficits that are related to the processing functions we attribute to these areas by means of their receptive field tuning properties (Dean, 1979; Heywood and Cowey, 1987; Maunsell and Newsome, 1987; Newsome et al., 1985; Schiller, 1993; Schiller and Lee, 1991; Wild et al., 1985). Thus, we arrive at a view whereby visual processing is subdivided into specific modules, each solving a particular subproblem of vision (Livingstone and Hubel, 1988; DeYoe and Van Essen, 1988). Although the strictness of this view is much disputed, it has profoundly pervaded our thinking about the roles of cortical areas in vision.