奖励学习

论文：The cerebellum is involved in reward-based reversal learning.

 

 

奖励学习中的神经变化

一些个体在完成有具体目标的任务时能够比其他个体更成功地获得奖励，但有可能调控这种以奖励为目的的学习活动的神经变化却不是很清楚。Tye等人训练大鼠来自己管理一种蔗糖奖励，发现奖励学习依赖于杏仁核（大脑中一个对情绪学习很重要的区域）中增加的活动及突触力量。不同动物所达到的学习水平与突触力量增强的程度有很强关联。增强对奖励学习过程中大脑变化的了解，将有助于为自然奖励学习缺陷或失常的奖励学习症状如药物上瘾或饮食失调等制定治疗干预方案。

Further, the greater the

proportion of neurons recruited to encode the reward-predictive cue,

the better the rat learned the cue–reward association, and the more

successful the rat was at earning rewards.

Because our in vivo recordings showed rapidly occurring changes

in cue-related firing in the LA during successful cue–reward learning,

we proposed that the mechanism underlying these changes was an

increase in synaptic strength of thalamic or cortical sensory afferents

onto LA neurons; we tested this hypothesis with ex vivo experimentation

(Supplementary Fig. 6). Rats were trained on a single session of

the same behavioural model and classified as learners (top 50%) or

non-learners (bottom 50%) as defined by our learning indices of task

efficiency and task accuracy (Supplementary Fig. 7).

These findings provide evidence of

a connection between LA synaptic plasticity and cue–reward learning,

potentially representing a key mechanism underlying goaldirected

behaviour.

Basolateral amygdala (BLA) neurons are phasically responsive to

reward-predictive cues8–11, which is consistent with the idea that cueevoked

neuronal firing emerges as a consequence of cue–reward

associations.

Recognizing that a cue predicts a reward enhances an

animal’s ability to acquire that reward; however, the cellular and

synaptic mechanisms that underlie cue–reward learning are

unclear. Here we show that marked changes in both cue-induced

neuronal firing and input-specific synaptic strength occur with the

successful acquisition of a cue–reward association within a single

training session.

but the results are generally consistent in showing that  training results in activity changes within a network of

brain regions previously implicated in domain-general aspects of WM (e.g., dorsolateral prefrontal cortex,posterior parietal cortex, basal ganglia)

 

Bray S, Shimojo S, O’Doherty JP. 2007. Direct instrumental

conditioning of neural activity using functional magnetic

resonance imaging-derived reward feedback. J Neurosci

27:7498–507.

 

Gläscher J, Daw N, Dayan P, O’Doherty JP. 2010. States versus

rewards: dissociable neural prediction error signals underlying

model-based and model-free reinforcement learning.

Neuron 66:585–95.

Grice GR. 1948. The relation of secondary reinforcement to

delayed reward in visual discrimination learning. J Exp Psychol

38:1–16.