Posts tagged visual perception
EyeWire launches today with J Day!
It’s time to mobilize a global community of citizen neuroscientists to trace the 3D structure of J Cells and understand how retinal connectomes relate to visual perception.
A specific type of retinal neurons called J Cells respond to stimuli that move downward on the retina (which is the same as upward in the visual world). Neuroscientists do not currently understand how the neural circuits of the retina cause the J Cell to respond in this way. That’s one of the reasons we built EyeWire. By playing EyeWire, you map the 3D structure of retinal neurons and their connections, and collaborate with neuroscientists at MIT, the Max Planck Institute for Medical Research, and Harvard.
Over the past several months, members of Sebastian Seung’s lab at MIT have been hard at work making sure EyeWire allows users to accurately contribute to research. During our beta period, an average of 30 to 50 people played EyeWire each day. Collectively, EyeWirers have mapped over 160,000 individual cubes since the beta went live in spring. We hope to dwarf these numbers in the coming months.
Check out a short video from Sebastian Seung, who shares why we created EyeWire and how you can get involved.
Filed under EyeWire J cells visual perception retinal connectomes neuroscience science
Learning to control brain activity improves visual sensitivity
Researchers at the Wellcome Trust Centre for Neuroimaging at UCL used non-invasive, real-time brain imaging that enabled participants to watch their own brain activity on a screen, a technique known as neurofeedback. During the training phase, they were asked to try to increase activity in the area of the brain that processes visual information, the visual cortex, by imagining images and observing how their brains responded.
After the training phase, the participants’ visual perception was tested using a new task that required them to detect very subtle changes in the contrast of an image. When they were asked to repeat this task while clamping brain activity in the visual cortex at high levels, those who had successfully learned to control their brain activity could improve their ability to detect even very small changes in contrast.
This improved performance was only observed when participants were exercising control over their brain activity.
Lead author Dr Frank Scharnowski, who is now based at the University of Geneva, explains: “We’ve shown that we can train people to manipulate their own brain activity and improve their visual sensitivity, without surgery and without drugs.”
In the past, researchers have used recordings of electrical activity in the brain to train people on various tasks, including cutting their reaction times, altering their emotional responses and even improving their musical performance. In this study, the researchers used functional magnetic resonance imaging (fMRI) to provide the volunteers with real-time feedback on brain activity. The advantage of this technique is that you can see exactly where in the brain the training is having an effect, so you can target the training to particular brain areas that are responsible for specific tasks.
"The next step is to test this approach in the clinic to see whether we can offer any benefit to patients, for example to stroke patients who may have problems with perception, even though there is no damage to their vision," adds Dr Scharnowski.
Filed under brain brain activity neurofeedback visual perception visual cortex neuroscience psychology science
The man whose brain ignores one half of his world
Alan Burgess doesn’t need a rhyme to remember the 5th of November. He’ll never forget the day he had his stroke. It left him with a syndrome known as hemispatial neglect and a strange new perspective.
I asked him how he explains this to other people. “I say it’s two different worlds,” says Burgess. “My old world finished on 5 November 2007 and the new world started the same day.”
His stroke damaged the parietal lobe on the right side of his brain, the part that deals with the higher processing of attention. The damage causes him to ignore people, sounds, and objects on his left.
"Hemispatial neglect typically occurs after a stroke," says Dr Paresh Malhotra, senior lecturer in neurology at Imperial College London. "It is not blindness in one eye, and it’s not damage to the primary sensory cortex, it’s a process of ignoring, for want of a better word, one side of space."
Read more
(Image credit: zeably.com)
Filed under brain hemiagnosia hemispatial neglect stroke visual perception psychology neuroscience science
Wouldn’t it be amazing if our bodies prepared us for future events that could be very important to us, even if there’s no clue about what those events will be?
Presentiment without any external clues may, in fact, exist, according to new Northwestern University research that analyzes the results of 26 studies published between 1978 and 2010.
Researchers already know that our subconscious minds sometimes know more than our conscious minds. Physiological measures of subconscious arousal, for instance, tend to show up before conscious awareness that a deck of cards is stacked against us.
"What hasn’t been clear is whether humans have the ability to predict future important events even without any clues as to what might happen," said Julia Mossbridge, lead author of the study and research associate in the Visual Perception, Cognition and Neuroscience Laboratory at Northwestern.
A person playing a video game at work while wearing headphones, for example, can’t hear when his or her boss is coming around the corner.
"But our analysis suggests that if you were tuned into your body, you might be able to detect these anticipatory changes between two and 10 seconds beforehand and close your video game," Mossbridge said. "You might even have a chance to open that spreadsheet you were supposed to be working on. And if you were lucky, you could do all this before your boss entered the room."
This phenomenon is sometimes called “presentiment,” as in “sensing the future,” but Mossbridge said she and other researchers are not sure whether people are really sensing the future.
"I like to call the phenomenon ‘anomalous anticipatory activity,’" she said. "The phenomenon is anomalous, some scientists argue, because we can’t explain it using present-day understanding about how biology works; though explanations related to recent quantum biological findings could potentially make sense. It’s anticipatory because it seems to predict future physiological changes in response to an important event without any known clues, and it’s an activity because it consists of changes in the cardiopulmonary, skin and nervous systems."
(Source: eurekalert.org)
Filed under vision visual perception conscious awareness future neuroscience psychology science
Electrical stimulation of the visual cortex may one day give image perception to blind people.
Work presented at the Society for Neuroscience meeting in New Orleans today suggests a way to create a completely new kind of visual prosthetic—one that restores vision by directly activating the brain.
In a poster session, researchers presented results showing how electrical stimulation of the visual cortex can evoke the sensation of simple flashes of light—including spatial information about those flashes.
While other researchers are trying to develop artificial retinas that feed visual signals into existing sensory pathways (see “A Retinal Prosthetic Powered by Light" and "Now I See You" for instance), the team behind the new work, from the Baylor College of Medicine and the University of Texas Health Science Center in Houston, is exploring the possibility of bypassing those routes all together. This could be vital for those whose retinas are unable to receive retinal stimulation.
The researchers used electrodes to stimulate the brains of three patients who were already undergoing brian surgery to treat epilepsy. All three were able to detect bright spots of light, called phosphenes, when certain regions of their brains were stimulated. And, in seven out of eight trials, the patients were able to correctly see the orientation of a phosphene—in one of two orientations, depending on the stimulation they received.
The work builds upon a study published by the same team in Nature Neuroscience this summer. In that study, the researchers defined which areas of the brain produce phosphene perception when patients’ brains were electrically stimulated.
A press release related to the earlier work says that the researchers “plan to conduct a larger patient study and create multiple flashes of light at the same time. Twenty-seven or so simultaneous flashes might allow participants to see the outline of a letter.”
Filed under blindness neuroscience prosthetics retina vision visual perception Neuroscience 2012 science
