Phasic excitation of ventral tegmental dopamine neurons potentiates the initiation of conditioned approach behavior: Parametric and reinforcement-schedule analyses

Frontiers in Behavioral Neuroscience

Anton eIlango¹  Dong V. Wang¹  Satoshi eIkemoto¹  Carl J. Broker¹  Andrew J. Kesner¹ 

[1] National Institute on Drug Abuse, National Institutes of Health;

关键词: Conditioning, Operant;    Dopamine;    Ventral Tegmental Area;    Reward;    Phasic firing;    optogenetics;   

DOI  :  10.3389/fnbeh.2014.00155

来源: DOAJ

【 摘 要 】

Midbrain dopamine neurons are implicated in motivation and learning.However, it is unclear how phasic excitation of dopamine neurons, which is implicated in learning, is involved in motivation.Here we used a self-stimulation procedure to examine how mice seek for optogenetically-induced phasic excitation of dopamine neurons, with an emphasis on the temporal dimension.TH-Cre transgenic mice received adeno-associated viral vectors encoding channelrhodopsin-2 into the ventral tegmental area, resulting in selective expression of the opsin in dopamine neurons.These mice were trained to press on a lever for photo-pulse trains that phasically excited dopamine neurons.They learned to self-stimulate in a fast, constant manner, and rapidly reduced pressing during extinction.We first determined effective parameters of photo-pulse trains in self-stimulation.Lever-press rates changed as a function of the manipulation of pulse number, duration, intensity and frequency.We then examined effects of interval and ratio schedules of reinforcement on photo-pulse train reinforcement, which was contrasted with food reinforcement.Reinforcement with food inhibited lever pressing for a few seconds, after which pressing was robustly regulated in a goal-directed manner.In contrast, phasic excitation of dopamine neurons robustly potentiated the initiation of lever pressing; however, this effect did not last more than 1 s and quickly diminished.Indeed, response rates markedly decreased when lever pressing was reinforced with inter-reinforcement interval schedules of 3 or 10 s or ratio schedules requiring multiple responses per reinforcement.Thus, phasic excitation of dopamine neurons briefly potentiates the initiation of approach behavior with apparent lack of long-term motivational regulation.

【 授权许可】

Unknown