Posts Tagged ‘Edvard Moser’

Navigation

January 6, 2019

A large part of this post is based on Helen Thomson’s book, “Unthinkable: An Extraordinary Journey Through the World’s Strangest Brains.” We have two basic means of navigation. One is to have specific landmarks that tell us what to do at that landmark. And the other is to have a map of the area of interest in our mind, a mental map. Although GPS’s might have an analogue of a mental map in the database they are interrogating, the instructions they provide to the user is a series of instructions as what to do when you arrive at what point. Point to point instructions are fine until you get lost or redirected and need to find an alternative route.

At one time cab drivers in London were tested on whether they had stored a mental map of London in the brains. It took years of study to pass this test, but to get the desired license they needed to memorize twenty-five thousand roads within a six-mile radius of Charing Cross station. An interesting and important question was if this knowledge affected their brains, and if so, which part of their brain. To answer this question, Eleanor Maguire scanned the brains of 79 trainee taxi drivers several times over four years as they began to learn what is called the Knowledge. Those who passed the test had a bigger posterior hippocampus than when they started, whereas there were no changes in trainee taxi drivers who had failed their exams or in 31 people whose age, education and intelligence were similar to the taxi drivers’, but who had never attempted to learn the Knowledge. Clearly, the hipppocampi were growing alongside navigational abilities.

How the hippocampus learns to navigate was done buy using rats as subjects. O’Keene placed a set of thin electrodes into their hippocampi, which could record the little spike of electricity that occurs when an individual neuron is communicating with its neighbors. O’keene discovered a type of cell that fired only when the animal was in a specific location. Each time the rat passed through this location—pop!—that cell would fire. A nearby cell seemed to care only about a different location. Pop! It would fire whenever the rat walked through that location. The next cell would respond only to another location, and so on. The combination of activity of many of these cells could tell you exactly where that rat was to within five square cm. O’keene named them place cells and showed how together they told the rest of the brain.

Place cells don’t do this job alone. They receive input from three other kinds of cells in a nearby region called the entorhinal cortex. One type of cell is called a grid cell, and was discovered by May-Britt Moser and Edvard Moser. The Mosers realized that our ability to navigate relies on us being able to think about how we are moving and where we have come from. Consider the way you head to the ticket machine in a parking lot and then reverse the movements of your body to return to your car. The Mosers discovered that grid cells were the neurons responsible for integrating this information into our cognitive map.

Our ability to recognize familiar landmarks is so important that there’s a part of the brain that is dedicated to the task.. This is the retrosplenial cortex and when it’s damaged it leads to severe problems in navigating.

Here is something we can do to improve our navigational skills. If you’re in a new area you should return to one point—your home base—often this will help you build a better mental map. You should also pay much more attention to your surroundings, take note of specific landmarks and think about their orientation to one another. And don’t forget to turn around or look backwards from time to time: it’s a trick that animals do to make it easier to recognize their way home.

It is also good to have a fold out map of the area of interest. This is a literal map than can inform your mental map.

The Disoriented Ape

December 15, 2018

The title of this post is identical to the first part of a title by Emma Young in the Features section of the 15 Dec. 18 issue of the New Scientist. The second half of the title is “Why clever people can be terrible navigators.” Apart from technology, which does little, if anything, to develop an individual’s ability to navigate. It is likely that a heavy reliance on these devices could reduce or destroy any abilities we might have.

There are two main approaches we use to navigate. Route-based navigation involves remembering landmarks on a particular journey: turn left at the church and then right at the park, and so on. This works pretty well in familiar towns or on regular journey, but what do you do if you are forced to take another route?

Mental mapping involves creating, consciously or unconsciously, a mental map of the environment. This approach is sometimes considered superior because it is more flexible and allows one to take shortcuts when appropriate. But it is more cognitively demanding.

Mary Hegarty of the University of California at Santa Barbara’s (UCSB) Spatial Thinking Lab says that most of us use both strategies, the trick being to get the balance right. “Good navigators probably select the best strategy for the job automatically.

Hegarty and colleagues put 140 UCSB students in a virtual reality maze. The maze contained 12 objects, including a chair and a duck, placed at various junctions. After being taught a route through the maze, the volunteers were started off at one object and asked to navigate to another. Sometimes the learned route was the shortest path and at other times it was quicker to take a novel route. Women were more likely to follow learned routes and to wander. Men showed a greater preference for trying to work out shortcuts, which call for mental mapping. On average, males were faster and covered less ground in reaching their target.

Hugo Spiers of University College London conducted a massive study that surveyed people’s navigational abilities using a mobile-phone-based game called Sea Hero Quest. In an analysis of more than 500,000 people from 57 countries, the best performers were living in nations with greater gender equality and greater economic wealth, which is associated with higher levels of education, which improves abstract problem solving. The presence of four Nordic countries in the top 10 has led Spiers to speculate that there may have been selection for good navigational abilities in their Viking and seafaring past. It might also help to have a culture of participating sports requiring navigation, such as orienteering,

Half of the Nobel Prize in 2014 went to John O’Keefe at University College London for discovering place cells in the hippocampus of rats. Each of these cells fired in a specific location at the animal moved around its enclosure. So by remembering patterns of place cell activity, a rat could effectively map its environment. The other half of the prize went to May-Britt Moser and Edvard Moser at the Norwegian University of Science and Technology for their discover of grid cells. Located near the hippocampus, they fire in groups, each making a discrete hexagonal region of ground as an animal moves across it. It is though that, by essentially unfurling a grid map over a two-dimensional space as it goes, the rat gets precise information about the distance between objects within it, including itself.

Place cells and grid cells have been found in human brains, as have a variety of other neurons specialized for navigation. Head direction cells encode the orientation of your head, providing a reference point for grid and place cells. Border cells fire when you get close to a boundary, such as a wall. Spatial view cells become active when you look at a place, even if you don’t actually go there.

What is the Key to LeBron James Phenomenal Performance?

May 24, 2018

And the answer is his superior memory. Sally Jenkins captured this in her article, “How is LeBron James always one move ahead? Let’s ask the scientists” in the 18 May 2018 issue of the Washington Post. She begins, “Much as his brute-strength shoulders and legs define LeBron James, it’s the stuff in his head that elevates him.”

Ms. Jenkins continues, “Much has been made of James show-offy display of memory in his postgame analysis of Game 1. Replay it and notice not just the accuracy but the detail: in narrating six sequences in proper order, he noted the time on the shot clock, who took each shot and missed what, where the ball was inbounded from, and Jayson Tatum’s use of a Euro-step and right hand on a layup. When he was done, listeners broke into applause.

Zach Hambrick, a cognition-performance expert at Michigan State said, “It’s remarkable, but not surprising.” It is not surprising because there is a strong connection between cognitive science and human performance. Hambrick said, “This is one of the bedrock findings in research on human expertise: that experts have superior memory for information within their domain.”

Research has shown what seems to be “photographic memory” is really extrapolation based on habit-worn paths of knowledge, the vestiges and traces left in the brain by experience.

Adriaan de Groot conducted a famous study of chess players in the 1960s. Pieces were shown on a board for five seconds and then removed. The players were asked to recall what they had seen. Novices remembered poorly. The more expert the players, the more pieces they could recall, and the locations of the pieces. An important point in this study, which is frequently not mentioned, is that the superior recall of the experts only occurred when they pieces on the board were placed in a meaningful manner as would be found in a game between experts. If pieces were arranged in a random, nonsensical manner, the masters’ performance differed little from the novices. If so arranged in a meaningful manner, grandmasters could recall virtually everything.

Masters of games don’t just build static memories, but have a remarkable ability to intuit. Ms. Jenkins writes, “James’s anticipation is inseparable from his memory. Ericsson cited a study of elite soccer players where they were shown a game and the screen was halted at an unpredictable point. The best players remembered not only who was where but also predicted where they would go next.

Ms. Jenkins writes, “Think about the processes involved as James scans the court while moving down the floor. The optic nerves absorb and transmit small peripheral details, then shift to a sudden zoom focus as he throws a glancing no-look bounce pass that hits Kevin Love in the hands mid-stride. Then his attention broadens again stereoscopically to capture the whole floor. The cognitive flexibility to go in and out of those states fluidly is highly learned. And yet little short of magic.”

In 2014 researchers John O’Keefe, Maybritt Moser, and Edvard Moser won the Nobel Prize for explaining how the brain navigates. They answered the questions: How do we perceive position, know where we are, find the way home? O’Keefe found a specific cell in the hippocampus that throws off a signal to mark a specific place. The Mosers found that neurons in the entorhinal cortex fire in fields with regularity. When they drew lines corresponding to the neuronal activity they saw a grid. So LeBron James has a geometric projection in his brain that acts as a computation coordinate system. And so do we, but LeBron makes a much more effective use of this system.

There still is the question as to how James’s brain discriminates among multiple similar memories. Andre Fenton has published a possible answer to this question in the journal “Neuron.” The answer is that the “place” signaling is not so much a constant remapping. Actually it is highly synchronized. Think of the neurons in James’s head as birds. Starlings, “Like a flock of starling that takes on different formations while still maintaining cohesion as a flock,” Fenton said. “He’s not recording like a videotape. He’s not rebuilding. He doesn’t rebuild a picture of what is going on. He watches it evolve continuously and fluidly. There is a flock, and it’s moving down the court, and everybody has a place. All these birds form a structure, and the structure is important. We call it a flock. He calls it a play.”

Fenton says that this is actually what all human beings do. HM would add that this is also what many infra human species do. Our brains learn a series of models over our lives and is constantly making predictions.

Phenoms like James are masters of assessing the likelihoods of things. With an amazingly good set of models and expectations—of opponents, of teammates and of how the ball will move, it can look like total omniscience.