Attention during natural vision warps semantic representation across the human brain
Unfortunately I could not access this article, so I’ve provided a video of the first author, Tolga Çukur at Berkeley, talking about the experiment published in Nature this year. He begins with an introduction and presents the results around 3:25. Here’s a nice summary from a wall street journal article:
People in an fMRI scanner watched a half-hour-long sequence combining very short video clips of everyday scenes. The scientists organized the video content into hundreds of categories, describing whether each segment included a plant or a building, a cat or a clock.
Then they divided the whole brain into small sections with a three-dimensional grid and recorded the activity in each section of the grid for each second. They then found the relationship between the patterns of brain activity and the content of the videos.
The twist was that the participants either looked for human beings in the videos or looked for vehicles. When they looked for humans, great swaths of the brain became a “human detector”—more sensitive to humans and less sensitive to vehicles. Looking for vehicles turned more of the brain into a “vehicle detector.” And when people looked for humans their brains also became more sensitive to related objects, like cats and plants. When they looked for vehicles, their brains became more sensitive to clocks and buildings as well.
In fact, the response patterns of most brain areas changed when people changed the focus of their attention. Something as ineffable as where you focus your attention can make your whole brain work differently.
Little is known about how attention changes the cortical representation of sensory information in humans. On the basis of neurophysiological evidence, we hypothesized that attention causes tuning changes to expand the representation of attended stimuli at the cost of unattended stimuli. To investigate this issue, we used functional magnetic resonance imaging to measure how semantic representation changed during visual search for different object categories in natural movies. We found that many voxels across occipito-temporal and fronto-parietal cortex shifted their tuning toward the attended category. These tuning shifts expanded the representation of the attended category and of semantically related, but unattended, categories, and compressed the representation of categories that were semantically dissimilar to the target. Attentional warping of semantic representation occurred even when the attended category was not present in the movie; thus, the effect was not a target-detection artifact. These results suggest that attention dynamically alters visual representation to optimize processing of behaviorally relevant objects during natural vision.
This is one of the most beautiful things I have ever seen. Never thought I would say that about a rat brain.
(Image via Harvard Center for Brain Studies)
…we are quite literally addicted to our guns. (…) …because the human brain evolved in an era of immediacy—when threats and rewards were of the lions, tigers and food variety—the dopamine circuitry has an inborn timing mechanism. If the reward follows the stimulus by roughly 100-200 milliseconds, it’s sitting in dopamine’s sweet spot. Firing a muzzle loader—for example—would certainly release dopamine, but it takes too long between multiple firings for a significant reward loop to be created. Firing an automatic weapon, though, sits close to the sweet spot—an assault weapon can fire a round every 100 milliseconds. Meaning not only are guns addictive, but automatic weaponry is far more addictive than most. [via, img]
Sleep and dreaming: The how, where and why
Within a few hours of reading this you will lose consciousness and slip into a strange twilight world. Where does your mind go during that altered state – or more accurately states – we call sleep? And what is so vital about it that we must spend a third of our lives sleeping? In these articles, we review the latest ideas on why we sleep and look at new ways to enhance its benefits.
Why do we spend roughly 10 percent of our waking hours with our eyes closed - blinking far more often than is actually necessary to keep our eyeballs lubricated? Scientists have pried open the answer to this mystery, finding that the human brain uses that tiny moment of shut-eye to power down.
Classical music, whether you love it or hate it, has been a powerful cultural force for centuries. While it no longer dominates the music scene, the argument for continued appreciation of the genre goes far beyond pure aural aesthetics. Classical music has been lauded for its ability to do everything from improve intelligence to reduce stress, and despite some exaggeration of its benefits, science shows us that it actually does have a marked effect on the brain in a number of positive ways.
With September being Classical Music Month, there’s no better time to learn a bit more about some of the many ways classical music affects the brain. Over the past few decades, there have been numerous studies on the brain’s reaction to classical music, and we’ve shared the most relevant, interesting, and surprising here, some of which may motivate you to become a classical aficionado yourself.
What if the external reality that each of us was observing and perceiving wasn’t the actual reality? What if we all saw things simply from a subjective experience, both as individuals and as a species? Is this a reality or the reality?
There are many reasons to ask such questions but one of them is they very way in which our brain perceives the world around us and conjectures experiences. Nerve cells in the brain are never really experienced for what they are; natural electrical activity. We don’t feel zips and zaps of impulses as we think and feel. Instead we transform them into a feeling attached to some outer reality. Rather than simply calculating the wavelength of blue and taking in the number, we see an ineffable sensation of blue in the sky, one that would be difficult to describe to a blind person. Rather than feeling pain, we experience stomach aches and headaches. As you can see, our brains attach interpretations for things such as brain to other parts of the body when all the experiences are simply in the brain itself. Color and pain are two of the many things that are created in the brain but appear to be part of an external reality.
So in other words, we could all probably be experiencing absolutely nothing for the way it truly is - but rather an interpretation of it in our minds.