Your visual cortex makes decisions?
Credit: Michigan State University
Michigan State University neuroscientist Jan Brascamp led a study
suggesting that the brain's visual cortex is more versatile than previously
believed. Here, Brascamp describes the effect that looking at multiple
images through a viewfinder can have on the brain.
Is this of interest to all writers? Probably not, but it is fascinating to this writer. I enjoy crossword puzzles, and I'm always surprised at the arcane information that is floating around inside my head. While I often can't find my keys or glasses, my brain comes up with obscure answers to the damnedest questions. For example, how do I know that Mary Queen of Scots first mother-in law's-name was Catherine de’ Medici when I've been searching for my wallet for twenty minutes? How do I know that? Why was the answer right there when I needed it? I took European history years ago.
Do you have similar experiences? You must. You wouldn't be human if you didn't.
As we learn more about how the 8 billion or so neurons that comprise our brain function, we're learning all sorts of sometimes amazing and sometimes obvious things. One unexpected result is that our optical cortex, a very complex and powerful area in the brain, not only makes sense of a three dimensional world from two dimensional input, it also makes decisions. I'm sure some of the decisions are "duck!", or "jump!" and that sort of life-saving action. This research implies that our visual cortex is involved in other decisions as well.
Here are the reports, with links to the reports in the attribution.
* * * * *
First, the report from a study published in 2014 about the current thinking on how the human brain functions:
How various brain areas interact in decisions
November 26, 2014, University of Zurich: Our decisions can be pictured in the brain. Scientists at the University of Zurich were able to show in a recent study which areas are most active in decision making. Often the so-called prefrontal cortex not only apparently shows increased activity during decisions that require self-control, but in general during decision making. The results could be of use in promoting decision skills in difficult decisions.
The value of a piece of chocolate cake can change. Someone who happens to be on a diet is more likely to choose a fruit dessert and judge the calorie-laden cake as unhealthy. Previous studies have shown that a specific network in the brain is active when a person must decide between various choices that vary depending on context. They emphasize the interaction between neurons in two brain areas of the prefrontal cortex -- the controlling area on the front side of the brain.
Prefrontal cortex shows increased activity in all decisions
Sarah Rudorf and Todd Hare of the Department of Economics of the University of Zurich were able to show those areas of the brain that are most active in the process of decision-making in their new study. Their results indicate that the neuronal interactions between the so-called dorsolateral and ventromedial prefrontal cortex not only play a central role when a person needs to decide between several options, but also are decisive in general for flexible decision making. This contradicts the belief that increased activity in the prefrontal cortex only occurs when self-control is required when deciding between conflicting preferences.
Previously, situations in experiments were only examined where people had to reconcile contradictory wishes in order to achieve an objective. For example, subjects had to measure financial profits against fairness interests or immediate returns against long-term payments. Sarah Rudorf and Todd Hare wondered what happens in the brain if there are no contradictory wishes and no self-control is needed.
In their study, the scientists used functional magnetic resonance imaging to examine the brains of 28 subjects while they answered choice questions. The participants could opt for actions that were always associated with financial profit. However, the rules that defined when an action led to the largest payoff changed several times during the course of the study.
Points of interaction for new therapies
"Decisions that require self-control are extremely important, as they directly affect a person's bodily, social, or financial welfare," explains Sarah Rudorf. The determination of the mechanisms in the brain that are not only involved in decisions requiring self-control but that are also used in general decisions could open new points of interaction for therapies. "We could develop training programs that support certain decision skills in difficult situations that depend on self-control," concludes Todd Hare.
Now, the primary report on your visual cortex making decisions:
Surprise: Your visual cortex is making decisions
The part of the brain responsible for seeing is more powerful than previously believed. In fact, the visual cortex can essentially make decisions just like the brain's traditional "higher level" areas, finds a new study led by a Michigan State University neuroscientist.
The findings, published in Nature Neuroscience, provide another piece of the puzzle in the relatively new quest to unlock the brain's secrets. Jan Brascamp, MSU assistant professor of psychology and lead investigator of the study, noted that the first cognitive psychology textbook didn't come out until the late 1960s.
"As a field, we're only at the beginning of trying to figure out how the brain works, and the visual system is a very good place to start," said Brascamp. "In that light, the current findings, which show that the visual system has a capacity we previously didn't expect, are an important step in the right direction."
Study participants were placed in an MRI scanner and shown two adjacent patterns of dots on a projection screen while their brain activity was monitored. By using a set of prisms, the researchers made sure that, unlike in normal situations, the participant's eyes were each looking at a different dot pattern, each presented on a different part of the screen.
The combination of differing patterns seen by the two eyes creates an optical illusion and perception switches between the two patterns as the brain tries to make sense of the contradictory information the eyes are providing. Previous research using MRI readings indicated the decision to switch perceptions is controlled by the association cortex, which is known for higher-level functions such as making choices, while the visual cortex handles the simpler task of processing visual information.
But in those past studies, participants knew the moment their perception changed because the illusion was obvious (such as the famous duck-rabbit image, meaning they were surprised. And the areas of the brain known to be involved with surprise and those involved with making decisions are very similar.
So Brascamp and colleagues took away the element of surprise by assuring their participants weren't aware the two patterns of dots were different. Although participants' perception went back and forth between the two patterns, the participants didn't notice. Among these participants, the increase in brain activity in the association cortex was gone, indicating the visual cortex was making the choice between perceptions on its own.
"That is one sense in which our study is counterintuitive and surprising," Brascamp said. "The part of the brain that is responsible for seeing, for the apparently 'simple' act of generating the picture in our mind's eye, turns out to have the ability to do something akin to choosing, as it actively switches between different interpretations of the visual input without any help from traditional 'higher level' areas of the brain."
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- Materials provided by University of Zurich. Sarah Rudorf and Todd Hare. Interactions between Dorsolateral and Ventromedial Prefrontal Cortex Underlie Context-Dependent Stimulus Valuation in Goal-Directed Choice. Journal of Neuroscience, November 2014.
- Materials provided by Michigan State University. Jan Brascamp, Randolph Blake, Tomas Knapen. Negligible fronto-parietal BOLD activity accompanying unreportable switches in bistable perception. Nature Neuroscience, 2015