On magnopyramidal temporal fields in the human brain - probable morphological counter parts of Wernicke's sensory speech region.

Posterior parts of the human superior temporal gyrus have been examined by means of stereomicroscopical observations of pigment preparations up to 800 microgram thick. As a rule, the proximal half of the first transverse gyrus of Heschl is covered by an extremely lightly pigmented conicortex which is surrounded by belt areas, a proncoinocortex anteriorly and paraconiocortical fields posteriorly and laterally. The paraconiocortex is divisble into a primitively organized part lying just behind the conicortical core and a more advanced portion forming the temporal magnopyramidal region. This extended lateralmost part of the paraconicortex is more or less richly endowed with unusually large and pigment-rich IIIc-pyramids. Third layer pyramidal cells showing densley aggregated lipofuscin deposits are rarely encountered within the human isocortex. As regards the temporal lobe, pyramids of this type, in general, do not occur outside the magnopyramidal region. The magnopyramidal region covers only a part of the temporal plane but extends much more in the lateral direction spreading over distal portions of the first and the second transverse gyri, posterior parts of the exposed surface of the superior temporal gyrus and those of its lower wall. The extension of the magnopyramidal region varies considerably from one side of the brain to the other. It is also subject to a pronounced variation from one individual to another. On account of its localization and its uniqueness in cortical structure, the temporal magnopyramidal region is considered to represent the morphological counterpart of the sensory speech centre of Wernicke.