Summary: J. theor. Biol. (1998) 195, 419438
Article No. jt970620
00225193/98/024419 + 20 $30.00/0 7 1998 Academic Press
Hebb and Darwin
Department of Neurobiology, SUNY, Stony Brook, NY 11794, U.S.A.
(Received on 31 March 1997, Accepted in revised form on 19 December 1997)
It is proposed that vertebrate brains, especially those of mammals, operate according to an
algorithm subsumable as ``synaptic Darwinism''. The key postulate is that genes and synapses
follow the same rules, because they act as autocatalytic, hypercyclic, units of selection.
Synapses replicate by quantally strengthening, and mutate by connecting new cells. Because
synapses relate pre- and post-synaptic firing, they perform a translation operation.
Furthermore the product of this operation, conjoint firing, favors replication (by Hebb's
Rule). The result is that variants are selected and patterns of connection automatically adopt
optimal configurations. These configurations are determined by scalar neuromodulatory
``reward'' signals applied globally to layers of neurons, which reduce spike frequency
adaptation and enhance Hebbian replication. Global or local control of mutation rates
provides further improvements in the Darwinian algorithm. All the processes and circuits
postulated have plausible, and often obvious, implementations. The result is that brains
evolve and adapt like large ecosystems.