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Reward and Decision Making

開催日 2014/9/12
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Activity of midbrain dopamine neurons evoked by visual conditioned stimuli presented in the V1 lesion-affected visual field

  • P2-231
  • 高桑 徳宏 / Norihiro Takakuwa:1,2 加藤 利佳子 / Rikako Kato:1 Redgrave Peter / Peter Redgrave:3 伊佐 正 / Tadashi Isa:1,2 
  • 1:自然科学研究機構・生理学研究所・認知行動発達機構研究部門 / Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan 2:総合研究大学院大学・生命科学研究科 / The Graduate Univ for Advanced Studies, Hayama, Japan 3:Dept Psychol, Univ of Sheffield, Sheffield, United Kingdom / Dept Psychol, Univ of Sheffield, Sheffield, United Kingdom 

Classical or Pavlovian conditioning is how animals learn associations between a reward-predicting (conditioned) stimulus (CS) and unconditioned reward (or punishment) (UCS). We hypothesized that the direct projection from the superior colliculus (SC) to dopamine (DA) neurons in the substantia nigra pars compacta (SNc) (Comoli E, et al, 2003) plays a key role in Pavlovian associative learning with conditioned visual stimuli. To test this hypothesis, we classically conditioned two monkeys with unilateral primary visual cortex (V1) lesions using visual CSs presented either in the lesion-affected or intact visual fields.
After the V1 lesion, our previous studies showed that residual visual inputs critically processed via the superior colliculus (Takaura et al. 2011; Kato et al. 2011).
In this study, the monkeys fixated a point in the center of screen, and visual reward-predicting CSs were presented in the lesion-affected visual field. Two kinds of CSs were included; one that predicted an immediate large reward (LR trial), while another that predicted a delayed small reward (SR trial). The cues could be discriminated by their position relative to the fixation point. The development of anticipatory conditioned responses showed that Pavolvian conditioning could be established when the visual CS was presented to the V1 lesion-affected visual field.
After conditioning, we recorded the responses of SNc dopamine neurons when the CSs were presented in the lesion-affected visual field. Clear visually-evoked phasic responses were elicited. In many cases, the amplitude of the phasic DA-response was larger in LR trials than that in the SR trials. Furthermore, the latencies of the responses were comparable to those elicited by CSs presented in the intact visual field. We conclude that the visual CS-related responses of the midbrain dopamine neurons were largely unaffected by the unilateral V1 lesion and that residual visual systems, most likely the superior colliuclus input.

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