Most Complex Thing Ever Actually More Complex Than We Thought

Many neuroscience textbooks around today will describe sensory modalities like hearing, vision, and touch as having corresponding regions of the brain, called primary sensory areas, that handle early processing of those senses. This is a simple picture pieced together from evidence that has been accumulating for decades, but the picture is beginning to change slightly.

Recent studies like this one published in Nature, have researchers considering the possibility that primary sensory areas for a given sense actually display patterns of activity in response to different types of sensory input. For example, the region known as the primary auditory cortex might respond separately and distinctly to sounds, sights, and even touches.

In past studies, the researchers note, “visual stimuli conveying information related to the auditory modality (like, a silent video clip of a barking dog or of a violin being played) have been shown to elicit activity in the auditory cortex.” In cases like these, however, it has been unclear whether the visual stimuli itself was causing activity in the auditory cortex, or if it was merely causing activity in the visual cortex, which then extended its influence to the auditory cortex.

The authors of this study used “stimuli that were simple … and presented in isolation" to get rid of some of the ambiguity. After exposing human participants to combinations of touch, painful touch, visual, and aural stimuli, the researchers analyzed fMRI scans of the associated primary sensory areas in the cortex. They found that "sensory input of any given modality elicits, per se, a characteristic pattern of activation in non-corresponding [primary sensory areas].” So, even if a visual stimulus had no obvious association to sound of any sort, it still activated the auditory cortex in its own special way.

It might sound like a trivial finding, but the researchers insist that it could well “prompt a reconsideration of how sensory information is coded in the brain,” and, quite frankly, such reconsideration may be coming at just the right time.

Studies in neuroscience are appearing more and more in public discourse. This is a good thing, but with increased attention to these studies comes an increased risk of people either misunderstanding or superficially assessing their results.

This study differs from many in that its results clearly reveal deeper complexities, as opposed to lending themselves easily to generalizations, as so many other findings unavoidably do. It provides an opportunity for people to see that the brain, arguably the most complicated thing humans have ever come across, is actually more complicated than even many researchers have traditionally recognized.

If that sounds disconcerting, take comfort in knowing that we could understand a lot less. The researchers were able to distinguish between visual cortex activity arising from aural versus tactile stimuli, as well as between two different tactile stimuli, which definitely constitutes progress.

The brain is not an unsolvable puzzle. It just takes a bunch of little insights like this to usher in things like new treatments for psychiatric disorders, as well as awesome sci-fi realizations like Luke Skywalker arms and mind-controlled drones.

This is where neuroscience is heading, one experiment at a time. Hold on to your hats.