The cortex of the anterior ectosylvian gyrus and adjoining ectosylvian and suprasylvian sulci was explored with tungsten microelectrodes to determine the distribution of responses to light cutaneous stimulation in barbiturate-anesthetized cats. Recordings were spaced between 125 and 250 micrometers and, in several cases, nearly all of the somatic areas in this cortex were explored in the same brain. Four somatic sensory areas were identified on the basis of responses properties, sequences of receptive fields, and cytoarchitecture. The largest area, which occupied the rostral and medial two-thirds to three-fourths of the exposed, relatively flat portion of the anterior ectosylvian gyrus, was called the second somatic sensory area (SII). Receptive fields in SII were primarily from the contralateral side of the body; they were well defined and somatotopically organized into an erect representation of the body. The top of the head was located next to a similar representation of the periphery in a portion of the first somatic sensory area (SI). Individual distal digits and toes occupied discrete components of the SII map. Another representation for the distal forelimb and hindlimb was noted medially along the lateral bank of the anterior suprasylvian sulcus. Receptive fields and response properties in this region were equivalent to those seen in SII proper. However, only a crude anteroposterior, fore- to hindlimb topographical organization was noted, but with more distal parts of the limbs generally located closer to the fundus of the sulcus in this medial representation. As the cytoarchitecture in this medial region was similar to the rest of SII it was considered a medial subdivision of SII. A third, topographically organized zone was located lateral to SII largely within the upper bank of the anterior ectosylvian sulcus and adjoining lateral crest of the anterior ectosylvian gyrus. Large, stockinglike, contralateral receptive fields were common; ipsilateral components to the receptive fields were present. Some individual digit receptive fields were located in the rostral part of the forelimb zone within the anterior ectosylvian sulcus. This lateral somatic area is probably equivalent to a fourth somatic sensory area (SIV) recently identified by Clemo and Stein ('82). Posterior to the hindlimb zones of SII and medial to SIV was another region that responded to cutaneous plus auditory stimulation. There was no detectable topography in this area; nearly all of the receptive fields were large, frequently bilateral, and often involved the whole body or all four extremities. This area's cytoarchitecture was comparable to previous descriptions of the suprasylvian fringe (Rose, '49). The location and physiology of these four areas were discussed in reference to previous controversies regarding the topography of the body representation in SII and the location of an acallosal zone in this region of cortex.

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Clinical and research workers are occasionally confronted by problems concerning cardiac innervation that may not be answered by the scanty details given in textbooks, and special articles usually deal with only one facet of the subject. A resume of available information may therefore prove helpful.The heart is innervated by both sympathetic and parasympathetic nerves, and afferents from the parietal pericardium are also conveyed through the intercostal and phrenic nerves. The autonomic nerves, like the somatic, are under the control of higher centres. HIGHER CENTRES CONTROLLING VISCERAL ACTIVITIESThe idea that visceral functions are controlled by higher centres was expressed by Willis (1664), but despite many intervening suggestive observations Hughlings Jackson (1873-74) was the first to state clearly, as a result of his clinical and pathological observations, that visceral activities must be represented at various levels in the central nervous system. Until comparatively recently the cerebral cortex was regarded as of subsidiary or negligible impoitance in relation to the autonomic nervous system, but it is now recognized that there is both motor and sensory autonomic representation in the cortex, with overlapping and close integration of somatic, autonomic, and other cortical areas, a fact explaining the common association of somatic and visceral effects and the correlation between somatic, autonomic, and mental states. Evidence on these matters has been obtained mainly by comparative researches, and the observations reported by many workers on the autonomic effects produced by stimulation, section, or ablation of various parts of the brain and cord have been reviewed or evaluated by Spiegel (1932), Hoff (1940), Miller (1942), Gellhorn (1943), Bucy (1949), Walshe (1951), Cloake (1952), and others. They reveal how gradually the importance of the frontal cortex, hypothalamus, and brain stem in controlling visceral activities was established. Recently, information about autonomic representation in the human brain has begun to accumulate as a result of clinical, operative, and pathological observations (Penfield and Rasmussen, 1950;Meyer et. al., 1947;Freeman andWatts, 1947, 1948;and Beck, 1950). These observations on the human brain tend to confirm in several respects the findings in animals, although the localization of centres, the pathways of the tracts involved, and the degree of response to stimulation are not always similar in man and animals. It can be stated, however, with reasonable certainty that the frontal lobes influence autonomic activities. This cortical participation in the control of visceral innervation is shared by subcortical centres in the hypothalamus, and perhaps in the corpus striatum and the anterior lobe of the cerebellum. These activities are correlated and integrated by two-way cortico-hypothalamic interconnections (Le Gros Clark, 1948

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