A team of researchers led by the University of California, Irvine has discovered that a neural marker for error detection in the brain’s visual system, previously thought to be premonitory, may actually require attention, and that subtle visual irregularities can be detected by other neural markers.
The results of the study were published in June in Plos Biology in a new study titled “Attention is required for a canonical brain signature of prediction error despite early stimulus encoding.”
According to predictive coding theory, a popular theory of how the brain efficiently processes its immediate sensory environment, additional processing is reserved for irregularities in sensory input that are labeled prediction errors.”
Alie G. Male, PhD, co-author and assistant project scientist, Department of Psychiatry and Human Behavior, UCI School of Medicine
For example, imagine that a person’s brain is a car engine; prediction errors are like a check engine light signaling that something is wrong. This check engine light is critical to starting the investigation process to fix the problem.
“However, there is a growing number of studies that have failed to show the well-known neural marker of prediction error in the brain’s visual system,” Male said. It is therefore problematic for those investigating atypical early visual processing indexed by absent or impaired prediction error signaling, she explained.
“For example, if a well-known neural marker for prediction error is not detected in a patient sample, aberrant early sensory processing, namely a failure to detect irregularities, may be erroneously inferred, when in fact the absence can be explained by the need to unmet experimental conditions, such as attention,” Male said.
To explain a failed condition with the earlier check engine light analogy, it’s like failing to see the check engine light before the engine overheats and assuming the sensors are malfunctioning when in fact overheating is indicated with another error signal, such as the temperature gauge, and the check engine light only comes on after the vehicle has been in motion for more than 10 minutes.
This study aims to qualify the electrophysiology of typical early sensory processing without attention, allowing others to later qualify the electrophysiology of atypical early sensory processing without attention, Male explained.
“We find that a well-known neural marker of prediction error in the brain’s visual system does not emerge for unobserved, subtle, visual irregularities, despite evidence that their relevant regularities are indeed encoded, even though such irregularities can be indexed by earlier electrophysiological signal in primary visual cortices,” she said.
In addition to this finding, their study also showed that subtle visual patterns are indeed encoded and monitored by electrophysiology. Further investigation of the conditions necessary for both indices of error signaling will provide a more robust model of early visual processing in the visual cortex.
Male’s research was motivated by the frustration of colleagues and peers with whom she discussed the difficulty of obtaining a reliable signal of the well-known neural correlate of prediction error signaling in the visual system, she said. They concluded that if there is no signal but they find evidence of encoding, they could further support the argument that the known neural correlate may not be the only index of signaling irregularities.
“We intend to further qualify the conditions required to display the well-known neural marker for error detection so that other researchers can adopt optimal parameters in their own error detection studies,” she said.
Male co-authored this study with Robert P. O’Shea of the Department of Psychology in the College of Science, Health, Engineering and Education at Murdoch University in Perth, Australia.
University of California, Irvine
Male, AG, et al. (2023) Attention is required for a canonical brain signature of prediction error despite early stimulus encoding. PLOS Biology. doi.org/10.1371/journal.pbio.3001866.