CENTRAL AUDITORY MECHANISMS 



393 



press the current area of substantial agreement of 

 several authors. 



In 1937, Kornmiiller (50) published the first map 

 of the cat's auditory cortex determined by recording 

 electrical responses to acoustic stimulation. His map, 

 seen in figure •], includes an area confined to middle 



FIG. 2. Lateral view of brain of cat. FR, rhinal fissure; GEA. 

 anterior ectosylvian gyrus; GEM, middle ectosylvian gyrus, 

 GEP, posterior ectosylvian gyrus; GPA, anterior pseudosylvian 

 gyrus; GPP, posterior pseudosylvian gyrus; GSA, anterior 

 suprasylvian gyrus; GSM, middle suprasylvian gyrus; GSP, 

 posterior suprasylvian gyrus; SEA, anterior ectosylvian sulcus; 

 SEP, posterior ectosylvian sulcus; SP, pseudosylvian sulcus; 

 and SSAI, middle suprasylvian sulcus. 



ectosylvian cortex. Between that time and 1941, two 

 other such maps were published. Bremer & Dow (17) 

 and Ades (i), using brief acoustic stimuli (clicks), 

 defined the area responsive to such stimulation largely 

 in the middle ectosylvian gyrus (fig. 4). The responsive 

 area of Bremer & Dow extends to the pseudosylvian 

 sulcus while that of Ades stops short of the sulcus. 

 Bremer & Dow studied the cytoarchitectonic char- 

 acteristics of the region also and found the somewhat 

 smaller area shown in the same figure to satisfy the 

 criteria of a sensory projection area. The study of 

 WooUard & Harpman (iio), in which they traced 

 Marchi degeneration after electrolytic lesions in the 

 media! geniculate body, defined the area shown in 

 figure 4 as the projection area of that nucleus. It is 

 interesting to note that the Woollard & Harpman 

 map, based on anatomical findings, corresponds more 

 closely with the Bremer & Dow electrical response 

 map than the latter does with their own cytoarchi- 

 tectonic map, which itself more nearly coincides with 

 Ades' electrical response map. 



The maps of the feline auditory cortex derived from 

 the foregoing studies from 1933 to 1941 share the 

 common feature of being considerably more restricted 

 than the much earlier work of Campbell indicated. 

 They were at the time regarded as being reasonably 

 consistent with each other and probably substantially 

 valid in defining the " primary' auditory projection 

 area, the only point of disagreement being the exten 



WOOLLARD 

 AND HARPMAN 



1939 



VOGT 1898 



KORNMULLER 1933 



BREMER AND DOW 1939 



ADES 1941 



FIG. 3 (top). Auditory area of cat as described by individuals named, shown by shaded areas. 

 All redrawn from originals on standard view. 



FIG. 4 (bottom). Auditory area of cat as described by individuals named, shown by shaded 

 areas. All redrawn from originals on standard view. In the map of Bremer & Dow, electrical re- 

 sponses to clicks could be obtained over both the horizonlalh and verlicatly shaded arcaj ; cytoarchi- 

 tectonically, the vertically shaded area satisfied the criteria for a sensory projection area. 



