Posts Tagged ‘Catherine de Lange’

Memory Special: How Can Two People Recall an Event So Differently?

November 30, 2018

This post has the same title as a Feature article by Catherine de Lange in 27 Oct ’18 issue of the “New Scientist.” The article begins, “ We each have a personal memory style determined by the brain, so next time you argue with someone about what really happened, remember that you may both be right.”

Signy Sheldon of McGill University notes that memories are only built when we retrieve them. And if they are retrieved a second time, they are built again. So if we’ve had an argument with someone it would be when you called the event to mind that you created a mental representation of what happened. And of all the details you could have picked out, you can bet you didn’t focus on the same ones as your sparring partner.

Sheldon says, “We are now understanding that there are strong individual differences in how people remember. And these differences are etched in our brain. This can be seen in people who have aphantasia, the inability to form mental images in the minds eye. It is not surprising that such people’s memories also lack a visual component, even though they can recall facts.

To study this further Sheldon and her colleagues asked people to complete a questionnaire about how they tend to remember, before having their brain scanned. The researchers found that people’s memory style was reflected in their brain connectivity. Those who were better remembering facts had more physical links between the hippocampus and the prefrontal cortex, which is involved in reasoning. Those with richly detailed “autobiographical memories”, by contrast, had more connectivity between the hippocampus and areas involved in visual processing. Sheldon says, “People’s brains are wired differently depending on how they naturally approach the act of retrieval.

In addition to individual brain differences, there are other reasons why two people might have conflicting memories of the same event. Their emotional response is one. Sheldon says, “Emotional events can be recalled much more naturally, almost like they are stamped in out minds.” It is as if we shine a spotlight on the things that really matter to us. What we remember will also be affected by whether we consider it useful. This is beneficial as it helps us learn lessons and bond with others. Sheldon notes, “The malleability of memory is often seen as something that’s broken, “but it’s really very adaptive.”

Memory Special: What Happens to Your Memories While You Sleep?

November 26, 2018

The title of this post is identical to a feature article by Catherine de Lange in the 27 Oct ’18 issue of the New Scientist.” We don’t need sleep to create a memory, but Bob Stickgold at Harvard Medical School says, “Sleep plays a critical role in determining what happens to newly formed memories.” Sleep determines what goes into long-term storage. It can also select which parts of a memory to retain. It also links new memories with established networks of remembrances. It discovers patterns and rules, and it is doing this every night all night long.

Somehow the sleeping brain chooses which memories to strengthen and which to ignore. Sleep is special. Anna Schipiro, also at the Harvard school says, “During slow-wave sleep, there is this release, a kind of beautiful set of interactions between different brain areas, that is specialized, and it looks different than what we see during awake periods. There is conversation between regions key to memory, including the hippocampus, where memories are processed into the cortex where long-term memories end up. This chatter might be allowing the cortex to pull out and see important information from new memories.

There is no need to recall everything, and sleep favors certain types of memory. It homes in on information that might be useful at a later date, and puts it into longer-term storage. Shapiro has found that merely telling people they will be tested on certain material helps them remember more of it after sleep.

Memories with an emotional component also get preferential treatment—especially negative emotions. Schipiro says, “If you have a memory that was really intense, sleep will help to preserve the memory, but decrease the emotionality. Obviously this could be crucial for our mental health. Stickgold says, “Post traumatic stress disorder might actually be a direct consequence of failure of those sleep-dependent processes that waken the intensity of emotional responses to memories.” And it could also help explain why getting too little sleep is bad for you. Negative memories become dominant over neutral and positive ones, for a start. Stickgold says, “We remember facts and events, but don’t manage to figure out what they really mean for us and our future.”

Here is Schipiro’s advice on studying for exams: “It’s much better to go to sleep between studying and taking a test than to stay awake all night studying.”

VR Headset Helps People Who Are Legally Blind to See

August 9, 2018

The title of this post is identical to the title of an article by Catherine de Lange in the News section of the 4 August 2018 issue of the New Scientist. Although this virtual reality headset does not cure the physical cause of blindness, the device does let people with severe macular degeneration resume activities like reading and gardening—tasks they previously found impossible.

Macular degeneration is a common, age-related condition. It affects about 11 million people in the US and around 600,000 people in the UK. Damage to blood vessels causes the central part of the eye, the macula, to degrade. This leaves people with a blind spot in the center of their vision, and can make those with the condition legally blind. Bob Massof at Johns Hopkins University says, “You can still see with your periphery, but it is difficult or impossible to recognize people, to read, to perform everyday activities.”

This new system is called IrisVision. It uses virtual reality (VR) to make the most of peripheral vision. The user puts on a VR headset that holds a Samsung Galaxy phone. It records the person’s surrounding and displays them in real time, so that the user can magnify the image as many times as they need for their peripheral vision to become clear. Doing so also helps to reduce or eliminate their blind spot.

Tomi Perski at Iris Vision, who also has severe macular degeneration, says “Everything around the blind spot looks, say, 10 times bigger, so the relative size of the blind spot looks so much smaller that the brain can’t perceive it anymore. When he first started using the device it was an emotional experience. He says, “I sensed that I could see again and the tears started coming.”

Perski says, “If I were to look at my wife—and I’m standing 4 or 5 feet away—my blind spot is so large I couldn’t see her head at all.” But when he uses IrisVision the magnification causes the blind spot to be relatively much smaller, so that it no longer covers his wife’s whole head, just a small part of her face. He says, “If I just move that blind spot I can see her whole face and her expression and everything.”

The software automatically focuses on what the person is looking at, enabling them to go from reading a book on their lap to looking at the distance without adjusting the magnification or zoom manually. Colors are given a boost because many people with macular generation have trouble distinguishing them (the cones are largely in the macular region), and users can place the magnification bubble over anything they want to see in even more detail, for example to read small print.

In a trial, 30 people used the system for two weeks, filling out questionnaires on their ability to complete daily activities before and after the period. David Rhew at Samsung Electronics Americas says, “They can now read, they can watch TV, they can interact with people, they can do gardening, They can can stuff that for years was not even a consideration.”
According to Rhew, the vision of participants was all but restored with the headset. Whew says, “The baseline rate of vision in the individuals came in at 20/400, which is legally blind, and with the use of this technology it improved to 20/30, which is pretty close to 20/20 vision.” 20/40 is usually the standard that lets people drive without glasses. 20/30 is even better. This is not to say they can drive with this device, but rather to indicate the quality of the vision.

The results have been presented at the Association for Research in Vision and Opthalmology annual meeting.

The headset is now being used in 80 ophthalmology centers around the US, and the next step is to adapt the software to work of other vision disorders.

The system costs $2500, which includes a Samsung Gear VR headset and a Galaxy S7 or S8 smartphone customized with the software.