Modeling some effects of frontal lobe damage: Novelty and perseveration. 
    Neural networks are presented which simulate some behavioral effects of frontal lobe damage.  On some cognitive tasks, frontal lesions cause perseveration of formerly rewarding choices of action.  On other tasks, frontal lesions cause approach to objects just because they are novel.  Both effects can be explained by weakening of signals between sensory and reinforcement loci. The networks that reproduce these data incorporate neural design principles developed for other purposes by Grossberg and his co-workers.  These design principles include adaptive resonance between two layers of sensory processing; attentional gating of synapses between layers; and competition among gated dipoles containing on-units and off-units.