The Japanese journal of neuropsychology

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ArticleTitle	The effect of punishment on decision making in Parkinson's disease
Language	J
AuthorList	Mutsutaka Kobayakawa^1)～3), Natsuko Tsuruya⁴⁾, Mitsuru Kawamura³⁾
Affiliation	¹⁾Department of Informatics, Tokyo University of Information Sciences ²⁾Brain Science Institute, Tamagawa University ³⁾Department of Neurology, Showa University School of Medicine ⁴⁾College of Informatics and Human communication, Kanazawa Institute of Technology
Publication	Japanese Journal of Neuropsychology: 30 (3), 233-240, 2014
Received	Sep 30, 2013
Accepted	Apr 21, 2014
Abstract	The Iowa Gambling Task (IGT) is a decision-making task in which participants make decisions according to the consequence of a behavior: reward or punishment. In the IGT, participants choose one of 4 decks that have different amounts and frequency of reward and punishment. Generally, the number of deck selections is used as an index of decision making. However, this index cannot discriminate the effect of reward from that of punishment on decision making, because each deck in the IGT brings about both reward and punishment. In the present study, we aimed to examine the effect of punishment on the IGT. We analyzed "non-used" negative feedback (NNF) following a punishment for the next decisions. NNF was defined as the condition wherein participants received a negative feedback in the previous trial and chose the same risky deck again in the following trial. To examine the effect of the elapsed time from punishment, we counted the number of NNFs after 1-5 and 6-10 trials of the punishment. We compared the NNF between healthy participants and patients with Parkinson's disease (PD), which we previously reported to show decision-making impairments in the IGT. In this study, we found that the NNF of the patients with PD after 1-5 trials of punishment was lower than, or equal to, that of the healthy control (HC) subjects. The NNF of patients with PD was lower than that of HCs for the decks that gave small reward and punishment. Meanwhile, the NNF after 6-10 trials of punishment was higher in the patients with PD. This was observed for the decks that gave large reward and punishment. These results indicate that punishment has an inhibitory effect, within the shorter period, in patients with PD. Moreover, patients with PD inhibit their behavior in response to a small punishment, when only a small reward is expected. In contrast, patients with PD choose "risky" decisions again after a longer period from the punishment. Together, these findings demonstrate that the effect of punishment is dependent on the amount of reward, and time from it.
Keywords	decision making, Parkinson's disease, Iowa gambling task, reward, punishment