How Basal Ganglia Outputs Generate Behavior

Figure 5

Negative feedback and control. (a) An example of the wrong application of control theory to the study of behavior in oculomotor studies [57]. In this diagram, there is no reference signal internal to the organism. The comparison function is performed in the external environment. Consequently, what is computed inside the organism is attributed to the external environment. And instead of receiving perceptual inputs, the input function receives error signals. This incorrect application of control theory has misled researchers for decades, leading to repeated rejections of negative feedback as an explanatory principle. (b) Illustration of cascade control proposed here. Two closed loop negative feedback control systems arranged hierarchically. Note that what is controlled is the perceptual variable, and the reference signal always comes from within the organism. In a hierarchy the higher level can adjust the reference of a lower level by sending a projection to the comparator function of the latter [58].

(a)

(b)