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Representation of reward feedback in primate auditory cortex.

Brosch M, Selezneva E, Scheich H - Front Syst Neurosci (2011)

Bottom Line: Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback.Correct identifications were rewarded with either a large or a small amount of water.Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institut für Neurobiologie Magdeburg, Germany.

ABSTRACT
It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

No MeSH data available.


(A,B) Reward-size coding of a sample multiunit in auditory cortex for two reward delays. The large reward arrived either early (530 ms, upper panel) or late (850 ms, lower panel) after bar release. Conventions as in Figure 2. (C) Reward-size coding in auditory cortex for the large (0.22 ml, red curve, 142 trials) and extra-large rewards (0.29 ml, orange curve, 53 trials). Symbols as in Figure 2.
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Figure 6: (A,B) Reward-size coding of a sample multiunit in auditory cortex for two reward delays. The large reward arrived either early (530 ms, upper panel) or late (850 ms, lower panel) after bar release. Conventions as in Figure 2. (C) Reward-size coding in auditory cortex for the large (0.22 ml, red curve, 142 trials) and extra-large rewards (0.29 ml, orange curve, 53 trials). Symbols as in Figure 2.

Mentions: We can thus rule out that reward-size responses were solely due to sounds or to motor acts associated with the monkeys licking the water reward. Similar initial licking activities during the time of significant firing differences always occurred, independent of whether there was water on the spout, and therefore did not explain the firing decrease in the no-reward condition (Figure 2, gray histograms). Only the subsequent periodic structure of the licking in the rewarded conditions was reflected to some extent by the firing periodicity of the neurons. The missing correlation between initial licking and initial firing was confirmed in a control experiment on 70 multiunits by comparing reward responses for two reward delays (Figures 6A,B). Licking commenced during the time of bar release, yet before arrival of the water; the subsequent firing pattern showed precisely the delays in water delivery. The encoding of the reward-size was further indicated in another control experiment on 12 multiunits that responded more strongly to an occasional extra-large reward (0.29 ml) than to the standard large reward of 0.22 ml (Figure 6C).


Representation of reward feedback in primate auditory cortex.

Brosch M, Selezneva E, Scheich H - Front Syst Neurosci (2011)

(A,B) Reward-size coding of a sample multiunit in auditory cortex for two reward delays. The large reward arrived either early (530 ms, upper panel) or late (850 ms, lower panel) after bar release. Conventions as in Figure 2. (C) Reward-size coding in auditory cortex for the large (0.22 ml, red curve, 142 trials) and extra-large rewards (0.29 ml, orange curve, 53 trials). Symbols as in Figure 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3037499&req=5

Figure 6: (A,B) Reward-size coding of a sample multiunit in auditory cortex for two reward delays. The large reward arrived either early (530 ms, upper panel) or late (850 ms, lower panel) after bar release. Conventions as in Figure 2. (C) Reward-size coding in auditory cortex for the large (0.22 ml, red curve, 142 trials) and extra-large rewards (0.29 ml, orange curve, 53 trials). Symbols as in Figure 2.
Mentions: We can thus rule out that reward-size responses were solely due to sounds or to motor acts associated with the monkeys licking the water reward. Similar initial licking activities during the time of significant firing differences always occurred, independent of whether there was water on the spout, and therefore did not explain the firing decrease in the no-reward condition (Figure 2, gray histograms). Only the subsequent periodic structure of the licking in the rewarded conditions was reflected to some extent by the firing periodicity of the neurons. The missing correlation between initial licking and initial firing was confirmed in a control experiment on 70 multiunits by comparing reward responses for two reward delays (Figures 6A,B). Licking commenced during the time of bar release, yet before arrival of the water; the subsequent firing pattern showed precisely the delays in water delivery. The encoding of the reward-size was further indicated in another control experiment on 12 multiunits that responded more strongly to an occasional extra-large reward (0.29 ml) than to the standard large reward of 0.22 ml (Figure 6C).

Bottom Line: Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback.Correct identifications were rewarded with either a large or a small amount of water.Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

View Article: PubMed Central - PubMed

Affiliation: Leibniz Institut für Neurobiologie Magdeburg, Germany.

ABSTRACT
It is well established that auditory cortex is plastic on different time scales and that this plasticity is driven by the reinforcement that is used to motivate subjects to learn or to perform an auditory task. Motivated by these findings, we study in detail properties of neuronal firing in auditory cortex that is related to reward feedback. We recorded from the auditory cortex of two monkeys while they were performing an auditory categorization task. Monkeys listened to a sequence of tones and had to signal when the frequency of adjacent tones stepped in downward direction, irrespective of the tone frequency and step size. Correct identifications were rewarded with either a large or a small amount of water. The size of reward depended on the monkeys' performance in the previous trial: it was large after a correct trial and small after an incorrect trial. The rewards served to maintain task performance. During task performance we found three successive periods of neuronal firing in auditory cortex that reflected (1) the reward expectancy for each trial, (2) the reward-size received, and (3) the mismatch between the expected and delivered reward. These results, together with control experiments suggest that auditory cortex receives reward feedback that could be used to adapt auditory cortex to task requirements. Additionally, the results presented here extend previous observations of non-auditory roles of auditory cortex and shows that auditory cortex is even more cognitively influenced than lately recognized.

No MeSH data available.