Since the anterior boundary of the excitable precentral cortex cannot be accurately defined in anatomical terms, and since the functions of the anterior part of the excitable cortex obviously differ from those of the posterior, a more precise terminology is needed to designate these functionally discrete regions. The term “premotor area” has been used in the past synonymously with the “intermediate precentral” region, but adequate anatomical definition has not hitherto been given. Since these regions correspond roughly with well-recognized cytoarchitectural fields, it is suggested that the following conventions be adopted (fig. 1). That:

  1. Motor area be restricted to the area giganto-pyramidalis, i.e. Area 4 of Brodmann, the Vogts and Foerster.

  2. Premotor area, which is also motor in function, include Area 6a (upper part) of the Vogts, the posterior part being designated 6a α and the anterior part 6a β.

  3. Frontal association areas include Areas 9, 10, 11 and 12 of Brodmann.

The term “excitable area” is applicable to both the motor and premotor regions.