Prepulse inhibition mechanisms and cognitive processes: a review and model.
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Acoustic Stimulation↗
Biomedical subjects
Nestor Schmajuk
Publications and source records attributed to Nestor Schmajuk.
Brain-behaviour relationships in latent inhibition: a computational model.
In a series of studies, we applied a neural network to study the neural bases of latent inhibition. We first designed a model able to handle behavioral data and then we investigated whether structures and neural elements in the brain were able to carry out the operations described by network. We demonstrated that the network was able to describe many of the behavioral properties of LI, and elucidate the effects of several manipulations of the dopaminergic system, the hippocampus, and the nucleus accumbens on LI, as well as some of the positive symptoms of schizophrenia. The results support the idea that a 'conceptual nervous system' can be successfully used to relate brain and behavior.
Animals↗
Latent learning, shortcuts and detours: a computational model.
Voicu and Schmajuk (Rob. Auto. Syst. 35 (2001a) 23) described a model of spatial navigation and exploration that includes an action system capable of guiding, with the help of a cognitive system, the search for specific goals as determined by a motivation system. Whereas in the original model the cognitive map stores information about the connectivity between places in the environment, in the present version the cognitive map also stores information about the paths traversed by the agent. Computer simulations show that the network correctly describes experimental results including latent learning in a maze, detours in a maze, and shortcuts in an open field. In addition, the model generates novel predictions about detours and shortcuts in an open field.
Journal Article↗
The Transition from Automatic to Controlled Processing.
The transition from automatic (unconscious) to controlled (conscious) processing is described in terms of a neural network model of classical conditioning ([Schmajuk et al., 1996]). In the framework of the network, an environmental stimulus is processed in controlled or conscious mode when Novelty and attention to the stimulus are large, and in automatic or unconscious mode otherwise. In the model, indirect dopamine (DA) agonists, such as amphetamine or nicotine, enhance the DA representation of Novelty, thereby increasing attention and engaging conscious processing of environmental stimuli. By contrast, DA receptor antagonists, such as haloperidol, reduce the DA representation of Novelty, thereby decreasing attention, and engaging unconscious processing of the stimuli.
Journal Article↗