TEMPERATURE REGULATION "CENTERS" 
an anatomical center, to constitute a focus of activity. This focus 
was manifested either by an evoked potential or (much later) by 
trains of EEG waves. Hypothetical centers were conceived as main- 
taining levels of such energy of activity, and these levels of activity 
could be raised or lowered by synaptic activation. Eventually, this 
localized concentration of energy became identified with the central 
excitatory state of Sherrington, and subsequently with pools of unit 
potentials in the spinal cord or other spatially distinct volumes of 
brain tissue. Sherrington apparently had a great deal to do with the 
informal application of 19th century thermodynamics to analysis of 
the brain, perhaps less in his scientific publications than in philo- 
sophical works such as Man on His Nature (1953), in which he de- 
scribes his more tenuous analogies. He wrote, for example, "A 
nerve centre is a place of junction of nerve-lines, and of departure 
for fresh ones.... Signals convergent via many lines may in the 
centres coalesce and reinforce.... It is at such junctions that inhib- 
itions occur. It canthere suppress action, or, no less important, can 
grade it by mode rating it. In the net work of conductors, it can switch 
off one line as another is switched on." (p. 164). This was clearly 
analogous to a telephonic relay system, which is not too different 
from the idea of a thermostat, a mechanical contrivance, which by 
analogy was also conceived to exist in the brain. 
This conception of the brain as a mosaic of centers, each with 
its characteristic levels of energy, involved assumptions that were 
particularly appropriate for the prevailing technique of testing. 
The electrode inherently has a focal relationship to the brain. The 
application of an electric current through the electrode was con- 
ceived to raise the energy level of a given center in the brain much 
as the release of energy of a peripheral nerve was increased by 
electrical stimulation. It is characteristic of the looseness of think- 
ing involving "centers" that the logical possibility that electrical 
stimulation might increase a central inhibitory state was seldom 
considered. In the early part of this century the electrode began to 
be used also for making circumscribed lesions, which were thought 
to diminish the level of energy available or producible by a center. 
This was conceived as an algebraic effect rather than in terms of 
altering a pattern of function in the brain. More recently, the elec- 
trode has been used to record the level of electrical activity at 
various points in the brain, and the assumption has been made that 
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