Reference code: | PT/FB/BL-2008-127.04 |
Location: | Arquivo PCA - Pasta 6/2008
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Title:
| Neural substrates of withholding impulsive actions in rat frontal cortex
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Publication year: | 2010
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URL:
| http://fens2010.neurosciences.asso.fr/abstracts/R6/A176_42.html
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Abstract/Results: | ABSTRACT:
Withholding impulsive actions for short term gains to achieve longer term goals is an important facet of goal-directed behavior. The frontal cortex has been hypothesized to exert top-down inhibition of impulsive actions, but little is known about the nature of the neural signals responsible for such control. To address this question, we have developed a novel impulse control task in rats and begun to investigate the neural signals of frontal cortical areas, namely medial frontal cortex (MFC) and secondary motor cortex (M2), during the task.
In the impulse control task, subjects interact with a waiting port and a reward port. While waiting, two tones are generated, the first at a fixed short delay (0.4 s) and the second at a longer random delay (exponentially-distributed, min. 0.7 s, approx. 2s mean). Responses after the first tone garner a reward, but the amount is 3-4 times larger after the second tone. For a given set of reward amounts and delays, the time a rat is willing to wait varies randomly from trial to trial, approximating the distribution of second tone delays.
To characterize neural signals related to impulse control, we made single-unit recordings from MFC and M2 neurons, testing for signals that correlated on a trial-by-trial basis with waiting time. While approximately 20% of neurons in M2 (109/548 neurons) showed activity that correlated with and predicted waiting time, only 6.6% of MFC neurons (8/122 neurons) showed such a predictive activity. Waiting-predictive neurons in M2 showed a variety of time courses of activity. The most frequent one was a phasic signal locked to waiting-port entry, but other neurons showed ramping activity peaking at waiting-port exit.
To test whether the predictive activity in M2 is specific to waiting action or not, we compared the activity during two impulse control tasks which require different actions for waiting, nose-poke for one task and lever-press for the other. Most of the predictive signals are specific to one type of waiting, which suggests the action specificity of the predictive signal.
These results establish a task suitable for studying impulse control, reveal properties of single neuronal activity in frontal cortex during the task and suggest a role of M2 in planning timing of actions.
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Accessibility: | Document does not exist in file
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Language:
| eng
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Author:
| Murakami, M.
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Secondary author(s):
| Vicente, M., Costa, G., Mainen, Z.
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Document type:
| Online abstract
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Number of reproductions:
| 1
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Reference:
| Murakami, M., Vicente, M., Costa, G., & Mainen, Z. (2010). Neural substrates of withholding impulsive actions in rat frontal cortex. FENS Abstr., vol.5, 176.42
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Indexed document: | No
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Keywords: | Impulse control / Frontal cortex / Rat / Neural activity
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