Adaptive Stimulus Representations: A Computational Theory of Hippocampal-Region Functions

We present a theory of cortico-hippocampal interaction in discrimination learning. The hippocampal region is presumed to form new stimulus representations which facilitate learning by enhancing the discriminability of predictive stimuli and compressing stimulus-stimulus redundancies. The cortical and cerebellar regions, which are the sites of long-term memory. may acquire these new representations but are not assumed to be capable of forming new representations themselves. Instantiated as a connectionist model. this theory accounts for a wide range of trial-level classical conditioning phenomena in normal (intact) and hippocampal-lesioned animals. It also makes several novel predictions which remain to be investigated empirically. The theory implies that the hippocampal region is involved in even the simplest learning tasks; although hippocampal-lesioned animals may be able to use other strategies to learn these tasks. the theory predicts that they will show consistently different patterns of transfer and generalization when the task demands change.

[1]  D. Alkon,et al.  Hippocampal lesions impair memory of short-delay conditioned eye blink in rabbits. , 1989, Behavioral neuroscience.

[2]  J. Theios,et al.  Acquisition and extinction of a classically conditioned response in hippocampectomized rabbits (Oryctolagus cuniculus). , 1972, Journal of comparative and physiological psychology.

[3]  W. Scoville,et al.  LOSS OF RECENT MEMORY AFTER BILATERAL HIPPOCAMPAL LESIONS , 1957, Journal of neurology, neurosurgery, and psychiatry.

[4]  P. Solomon,et al.  Latent inhibition and stimulus generalization of the classically conditioned nictitating membrane response in rabbits (Oryctolagus cuniculus) following dorsal hippocampal ablation. , 1975, Journal of comparative and physiological psychology.

[5]  R. Passingham The hippocampus as a cognitive map J. O'Keefe & L. Nadel, Oxford University Press, Oxford (1978). 570 pp., £25.00 , 1979, Neuroscience.

[6]  R. Hirsh The hippocampus and contextual retrieval of information from memory: a theory. , 1974, Behavioral biology.

[7]  R. Nosofsky Choice, similarity, and the context theory of classification. , 1984 .

[8]  Geoffrey E. Hinton,et al.  Learning internal representations by error propagation , 1986 .

[9]  R. Lubow Latent inhibition. , 1973, Psychological bulletin.

[10]  J N Rawlins,et al.  The hippocampus and conditioning to contextual cues. , 1987, Behavioral neuroscience.

[11]  P. Solomon,et al.  Altered activity in the hippocampus is more detrimental to classical conditioning than removing the structure. , 1983, Science.

[12]  L. Nadel,et al.  The Hippocampus as a Cognitive Map , 1978 .

[13]  R. Sutherland,et al.  Configural association theory: The role of the hippocampal formation in learning, memory, and amnesia , 1989, Psychobiology.

[14]  N. Mackintosh,et al.  Mechanisms of animal discrimination learning , 1971 .

[15]  W. B. Orr,et al.  Hippocampectomy selectively disrupts discrimination reversal conditioning of the rabbit nictitating membrane response , 1983, Behavioural Brain Research.

[16]  R. E. Lubow,et al.  The Context Effect: The Relationship Between Stimulus Preexposure and Environmental Preexposure Determines Subsequent Learning. , 1976 .

[17]  R. Shepard Stimulus and response generalization: deduction of the generalization gradient from a trace model. , 1958, Psychological review.

[18]  R. Nosofsky Choice, similarity, and the context theory of classification. , 1984, Journal of experimental psychology. Learning, memory, and cognition.

[19]  N J Mackintosh,et al.  An analysis of transfer along a continuum. , 1970, Canadian journal of psychology.

[20]  L. Squire Memory and Brain , 1987 .

[21]  G. Winocur,et al.  The hippocampus and conditioning to contextual cues. , 1987, Behavioral neuroscience.

[22]  L. Nadel,et al.  Context and conditioning: A place for space , 1980 .

[23]  Geoffrey E. Hinton Connectionist Learning Procedures , 1989, Artif. Intell..

[24]  H. Eichenbaum,et al.  Hippocampal system dysfunction and odor discrimination learning in rats: impairment or facilitation depending on representational demands. , 1988, Behavioral neuroscience.

[25]  M. Gluck,et al.  Hippocampal mediation of stimulus representation: A computational theory , 1993, Hippocampus.

[26]  R. Rescorla A theory of Pavlovian conditioning : Variations in the effectiveness of reinforcement and nonreinforcement , 1972 .

[27]  G. Buzsáki Two-stage model of memory trace formation: A role for “noisy” brain states , 1989, Neuroscience.