A theory of cerebellar cortex

Marr, David

doi:10.1113/jphysiol.1969.sp008820

Cited by 2,828 publications

(1,290 citation statements)

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“…7). Neurons carrying prediction errors are also found in brain structures other than the dopamine system 7 , particularly in the climbing ®bre projection to cerebellar Purkinje cells 11,12,14,15 .…”

Section: Discussionmentioning

confidence: 99%

Dopamine responses comply with basic assumptions of formal learning theory

Waelti

Dickinson

Schultz

2001

Nature

930

749

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According to contemporary learning theories, the discrepancy, or error, between the actual and predicted reward determines whether learning occurs when a stimulus is paired with a reward. The role of prediction errors is directly demonstrated by the observation that learning is blocked when the stimulus is paired with a fully predicted reward. By using this blocking procedure, we show that the responses of dopamine neurons to conditioned stimuli was governed differentially by the occurrence of reward prediction errors rather than stimulus±reward associations alone, as was the learning of behavioural reactions. Both behavioural and neuronal learning occurred predominantly when dopamine neurons registered a reward prediction error at the time of the reward. Our data indicate that the use of analytical tests derived from formal behavioural learning theory provides a powerful approach for studying the role of single neurons in learning.Classic theories assume that predictive learning occurs whenever a stimulus is paired with a reward or punishment 1,2 . However, more recent analyses of associative learning argue that simple temporal contiguity between a stimulus and a reinforcer is not suf®cient for learning and that a discrepancy between the reinforcer that is predicted by a stimulus and the actual reinforcer is also required 3±6 . This discrepancy can be characterized as a`prediction error' 7 . Presentations of surprising or unpredicted reinforcers generate positive prediction errors, and thereby support learning, whereas omissions of predicted reinforcers generate negative prediction errors and lead to reduction or extinction of learned behaviour. Expected reinforcers do not generate prediction errors and therefore fail to support further learning even when the stimulus is consistently paired with the reinforcer. Modelling studies have shown that neuronal messages encoding prediction errors can act as explicit teaching signals for modifying the synaptic connections that underlie associative learning 8±17 .Current research suggests that one of the principal reward systems of the brain involves dopamine neurons 18±21 . Both psychopharmacological manipulations and lesions of the dopamine system impair reward-driven behaviour of animals 18,21 , and drugs of abuse, which provide strong arti®cial rewards, act via dopamine neurons 19,20 . Neurobiological investigations of associative learning have shown that dopamine neurons respond phasically to rewards in a manner compatible with the coding of prediction errors 22±28 , whereas slower dopamine changes are involved in a larger spectrum of motivating events 18,28,29 . Dopamine neurons show short-latency, phasic activations when rewards occur unpredictably, they are not modulated by fully predicted rewards and show phasically reduced activity when predicted rewards are omitted. During initial learning, when rewards occur unpredictably, dopamine neurons are activated by rewards. They gradually lose the response as the reward becomes increasingly predicted 24,25,27 . The co...

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Section: Discussionmentioning

confidence: 99%

Dopamine responses comply with basic assumptions of formal learning theory

Waelti

Dickinson

Schultz

2001

Nature

930

749

View full text Add to dashboard Cite

show abstract

“…However, one needs to be cautious about the implications of this data. A replay of recent memories in hippocampus would certainly be useful for training downstream structures [24,102,215], but, as yet, there is no direct evidence that replay of hippocampal representations have any influence on neocortical representations.…”

Section: A1 Hippocampal Representational Replaymentioning

confidence: 99%

“…Place fields are only seen during theta states; during LIA states, cells fire during sharp-waves, independent of the location of the animal [94,150]. The theories that predicted replay of hippocampal states during sleep suggest that information is written into hippocampus during theta and read out during LIA [24,102,215]. While superficial entorhinal cortex (input to hippocampus) shows cellular activity correlated to theta [29,31], deep entorhinal cortex (output from hippocampus) shows cellular activity related to LIA and sharp-waves [30,31].…”

Section: A1 Hippocampal Representational Replaymentioning

confidence: 99%

The hippocampal debate: are we asking the right questions?

Redish

2001

Behavioural Brain Research

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For years, the debate has been: 'Is the hippocampus the cognitive map?' or 'Is the hippocampus the core of memory?' These two hypotheses derived their original power from two key experiments-the cognitive map theory from the remarkable spatial correlates seen in recordings of hippocampal pyramidal cells and the memory theory from the profound amnesias seen in the patient H.M. Both of these key experiments have been reinterpreted over the years: hippocampal cells are correlated with much more than place and H.M. is missing much more than just his hippocampus. However, both theories are still debated today. The hippocampus clearly plays a role in both navigation and memory processing. The question that must be addressed is rather: 'What is the role played by the hippocampus in the navigation and memory systems?' By looking at the navigation system as a whole, one can identify the major role played by the hippocampus as correcting for accumulation errors that occur within idiothetic navigation systems. This is most clearly experimentally evident as reorientation when an animal is lost. Carrying this over to a more general process, this becomes a role of recalling a context, bridging a contextual gap, or, in other words, it becomes a form of recognition memory. I will review recent experimental data which seems to support this theory over the more general spatial or memory theories traditionally applied to hippocampus.

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“…The alignment of parallel ¢bres (PFs) along the length axis of a folium (the PF or coronal axis) and perpendicular to the plane of Purkinje cell (PC) dendrites is the basis for most theories of cerebellar functioning (Braitenberg and Atwood, 1958;Marr, 1969;Eccles, 1973;Braitenberg et al, 1997). However, most experimental studies failed to demonstrate the beam-like patterns of PC activity that were predicted to emerge from this anisotropy (Bower and Woolston, 1983;Cohen and Yarom, 1998; but see Garwicz and Andersson, 1992).…”

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confidence: 99%