Do you like surprises? If you don’t, it might be because our brain works very hard to avoid being surprised.
The brain always tries to predict its own future as accurately as possible. For instance, when we watch a movie scene that appears to be unpredictable, our brain still tries to predict what will happen next.
Researchers suggest that the brain relies on predictions rather than detailed information of each new sensory event.
If this is true, the main task for the sensory neurons is to filter the information it receives and pass on the information that is truly new – the surprising info.
So far predictive coding in neurons has been largely studied in the visual domain in non-human primates, but in humans the research evidence is still little.
In a study newly published in eLife, researchers examined predictive coding in the auditory cortex in human brain.
The experiment was conducted in 3 patients undergoing neurosurgical treatment for epilepsy.
Researchers got a rare opportunity to directly measure the neural oscillations (i.e. rhythmic or repetitive neural activity in the central nervous system). The patients listened to complex tones that sounded random.
Researchers found that “gamma” oscillations encoded the degree of surprise triggered by a given sound, and that slower “alpha” and “beta” oscillations encoded predictions made by the brain.
Previous research has shown that “alpha” and “beta” oscillations encoded predictions in visual cortex, and this study shows that the two types of oscillations also encode predictions in auditory cortex.
The question still remains as to which aspects of neural communication we are missing by not being able to routinely record neural activity directly from the surface of the human brain.
So we are surely in for more surprises, whether we like it or not.
Citations: Sedley W, Gander PE, Kumar S, Kovach CK, Oya H, Kawasaki H, Howard MA, Griffiths TD. (2016). Neural signatures of perceptual inference. eLife, 5: e11476. doi: 10.7554/eLife.11476
Obleser J. (2016). Tell me something I don’t know. eLife, 5. pii: e15853. doi: 10.7554/eLife.15853.
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