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George E. Carvell, PhD, PT   University of Pittsburgh
 
NERVOUS SYSTEM ORGANIZATION: HETERARCHY MODEL
muscles
muscles
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Hierarchy
Heterarchy
1. functional polarization
1. reciprocal connectivity
3. functional segregation
3. distributed function
2. elemental properties
2. emergent network properties
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 = command neuron
 = oscillator neuron
 = motor neuron
 = ‘multitasking’ neuron
W. J. Davis “Organizational Concepts in the Central Motor Networks of Invertebrates” IN: Neural Control of Locomotion R.M. Herman, S. Grillner, P.S.G. Stein, & D.G. Stuart (eds) Advances in Behavioral Biology. Vol. 18  New York: Plenum Press, pp. 265-292, 1976 (adapted from fig. 5 pp. 282-283)
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Motor Control modeled as a distributed system. Neurons are capable of multiple ‘tasks’ when networked and reciprocally connected. In Davis’ model most neurons are capable of some degree of ‘multi-tasking’, and control is distributed among neurons at multiple ‘levels’ in a more ‘democratic’ fashion. However, some neurons still have privileged access to information in complex brains. His model is based on invertebrate nervous systems.