NEURONAL INTEGRATIVE MECHANISMS 19 



for behavior and mental phenomena (Sherrington, -1951 ; Eccles, 1953). 

 The gap at present is certainly staggering. It must be realized that much 

 of our knowledge of brain physiology, while contributing to the better 

 localization and fragmentation of the problem, actually still consists in 

 specifying the nature of the phenomena to be explained without un- 

 equivocally helping to decide whether these will be explicable in terms of 

 the known properties of neural units or of those plus as yet unknow^n 

 properties or will not be explicable in any physiological terms. 



I will confine myself here to the mere statement of my own faith — and 

 it is just that — that no extension of the known mechanisms will be found 

 adequate to explain higher activities of central nervous systems, but that 

 we need not fall back on a dualism. Our position is a little like a meteor- 

 ologist or oceanographer trying to account for the great events of the ocean 

 and atmosphere from the known properties of the individual atomic species. 

 I believe we have yet to discover fundamental new properties and relations 

 at the level of masses of neurons — emergents in the old sense of inhering 

 in but not readily predicted from a catalog of unit properties. One example 

 may be the slowly traveling waves of synchronous, slow, subthreshold po- 

 tential change in neuron masses. 



I believe it will require such emergent mechanisms to understand, for 

 example, complex integrations like that which must accompany the central 

 control of afferent influx — now well known for several modalities. There 

 must be a central correction for the control so that the world is interpreted 

 reasonably correctly. Or again we may think of the Efferenzkopien of 

 van Hoist which similarly corrects for the distortions of input caused by our 

 movements. The plausibly postulated energies, drives, appetitive behavior, 

 releasers, and other entities of behavioral science and above all the amazing 

 phenomenon of nearly nonlocalizable, anaesthesia- and shock-proof learn- 

 ing appear to me, at once, to require such still undiscovered physiological 

 parameters and to be the stimulus to new levels of search. 



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