The connectionist simulation of aphasic naming.
The simulation of language disorders using interactive activation (IA) networks and connectionist systems is discussed. An existing IA account of aphasic naming is described, in which two network parameters (decay rate and connection strength) are varied to fit the error production of an aphasic patient. Fairly similar results can be obtained through modification of additional parameters, including the so-called "shared weight increase factor" linking lexical and semantic units. This leads us to consider simulation of aphasic naming using connectionist networks which do not require explicit variation of network parameters. A modular connectionist architecture is presented, in which semantic-lexical and phonological knowledge are instantiated using self-organizing Kohonen maps, while connections between them are implemented using Hebbian networks; a linear connectionist network (Madaline) is used to simulate nonword repetition. The Hebbian connections are lesioned in order to reproduce the patient's naming errors.
Wright
J F
JF
Department of Mathematical and Computing Sciences, University of Surrey, Guildford, United Kingdom. J.Wright@surrey.ac.uk
Ahmad
K
K
D001037:Aphasia / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology; D003198:Computer Simulation; D006801:Humans; D008297:Male; D016571:Neural Networks, Computer; D014705:Verbal Behavior