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- Title
Variable Sequencing Is Actively Maintained in a Well Learned Motor Skill.
- Authors
Warren, Timothy L.; Charlesworth, Jonathan D.; Turner, Evren C.; Brainard, Michael S.
- Abstract
Variation in sequencing of actions occurs in many natural behaviors, yet how such variation is maintained is poorly understood. We investigated maintenance of sequence variation in adult Bengalese finch song, a learned skill with rendition-to-rendition variation in the sequencing of discrete syllables (i.e., syllable “b” might transition to “c” with 70% probability and to “d” with 30% probability). We found that probabilities of transitions ordinarily remain stable but could be modified by delivering aversive noise bursts following one transition (e.g., “b→c”) but not the alternative (e.g., “b→d”). Such differential reinforcement induced gradual, adaptive decreases in probabilities of targeted transitions and compensatory increases in alternative transitions. Thus, the normal stability of transition probabilities does not reflect hardwired premotor circuitry. While all variable transitions could be modified by differential reinforcement, some were less readily modified than others; these were cases that exhibited more alternation between possible transitions than predicted by chance (i.e., “b→d ” would tend to follow “b→c ” and vice versa). These history-dependent transitions were less modifiable than more stochastic transitions. Similarly, highly stereotyped transitions (which are completely predictable) were not modifiable. This suggests that stochastically generated variability is crucial for sequence modification. Finally, we found that, when reinforcement ceased, birds gradually restored transition probabilities to their baseline values. Hence, the nervous system retains a representation of baseline probabilities and has the impetus to restore them. Together, our results indicate that variable sequencing in a motor skill can reflect an end point of learning that is stably maintained via continual self-monitoring.
- Subjects
NEUROSCIENCES; SOCIETY finch; NEURAL circuitry; NERVOUS system; MOTOR ability; AVERSIVE stimuli; SELF-monitoring (Psychology)
- Publication
Journal of Neuroscience, 2012, Vol 32, Issue 44, p15414
- ISSN
0270-6474
- Publication type
Article
- DOI
10.1523/JNEUROSCI.1254-12.2012