A common framework for perceptual learning. Seitz, Dinse. Current Opinion in Neurobiology 2007.

  1. Perceptual learning can occur in periods of “… unattended and  passive sensory stimulation.”
  2. Although adults lose plasticity, “… perceptual abilities can be sharpened with extensive exposure and training.”
    1. Example: radiologists learn to distinguish patterns that laypeople generally can’t detect
  3. The effects of this training is often very closely fitted to the training stimulus. “The lack of generalization is taken as evidence that learning might be mediated by cells in early sensory areas.”
  4. How do we know what to learn?
  5. There are two common theories, which have opposing viewpoints
    1. Evidence that shows that attention does have a role in perceptual learning is taken to mean that passive learning doesn’t occur or isn’t important
    2. On the other hand, there is evidence that passive learning does occur
  6. This paper attempts to reconcile those two perspectives
  7. Vision is most commonly studied in perceptual learning.  Studies there show the nature of the task, and not only the stimulus itself effects what is learned
    1. There are similar results in studies on touch
  8. These results indicate that attention is necessary for learning
  9. On the other hand results show that exposure to stimulus without external reinforcement can lead to learning 
    1. The literature on this seems to be stronger for auditory stimulus than visual
  10. There is also a link to “… acetylcholine and dopamine, which gate learning, and thus restrict sensory plasticity and protect sensory systems from undesirable plasticity.”  Theese neuromodulators are also linked to attention, so they may provide a mechanism by which attention and reinforcement are related
  11. <Discuss an experiment involving coactivation showing that when that occurred unreinforced learning occurred.  What is coactivation though?  I assume it means two stimuli being presented in a way that makes them correlated>
  12. One experiment shows that passive learning is learning is possible in instances where either coactivation occurs, or the frequency has certain temporal characteristics (high frequency)
  13. High frequency direct electrical stimulation has been shown to cause changes in cortical map. Magnetic stimulation through TMS can as well
  14. “In this review, we have summarized recent findings showing that perceptual learning can occur only under training conditions but also in situations that lack attention and reinforcement.  To explain their effectiveness, we suggest that all these types of learning occur through a similar process – namely, that the key to learning is that sensory stimulation needs to be sufficient to drive the neural system past the point of a learning threshold.”
  15. Typical sensory inputs aren’t sufficient to drive learning by themselves, but attention or reinforcement can shift the learning threshold to a point where learning does occur with the same stimulus
  16. Electrical/magnetic stimulation can also shift this threshold
  17. “We postulate that this common learning mechanism involves a Hebbian learning process gated neuromodulatory signals (e.g. acetylcholine and dopamine) that are activated both in attentional and reinforcement paradigms.”  But more research is needed to test this theory

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