Posts Tagged ‘cell assemblies’

A View of the Reading Brain

October 19, 2018

This post is taken from “READER COME HOME: The Reading Brain in the Digital World” by Maryanne Wolf. Please excuse the detail, but it is important to gain an appreciation of what is involved in reading. The brain’s design is with the principle of “plasticity within limits.” The brain is able to go beyond its original biological functions—like vision and language—to develop biologically unknown capacities such as reading and numeracy. To do so, it forms a new set of pathways by connecting and sometimes repurposing its older and more basic structures. Faced with something new to learn, the human brain not only rearranges its original parts, but is also able to refit some of its existing neuronal groups in those same areas to accommodate the particular needs of the new function. The brain recycles and even repurposes neuronal networks for skills that are cognitive or perceptually related to the new one, Wolf writes, “This ability to form newly recycled circuits enables us to learn all manner of genetically unplanned-for activities—from making the first wheel, to learning the alphabet, to surfing the net while listening to Coldplay and sending tweets. None of the activities is hardwired or has genes specifically dedicated to its development; they are cultural inventions that involved cortical takeovers.” As there is no genetic blueprint for reading, there is no one ideal reading circuit. There can be different ones.

In addition to neuroplasticity, there is the concept of cell assemblies formulated by the Canadian psychologist Donald Hebb. The concept is that cells that fire together wire together. These specialist groups build the networks that allow us to see the smallest features of a letter or hear the tiniest elements in the sounds of language, literally in milliseconds. Cell specialization enables each working group of neurons to become automatic in its specific region and to become virtually automatic in its connections to the other groups or networks in the reading circuit. For reading to occur, there must be sonic-speed automaticity for neuronal networks at a local level, which, in turn, allows for equally rapid connections across entire structural expanses of the brain. So, whenever we name even a single letter, we are activating entire networks of specific neuronal groups in the visual cortex, which correspond to entire networks of equally specific language-based cell groups, which correspond to networks of specific articulatory-motor cell groups—all with millisecond precision. Multiply this scenario a hundredfold when the task is to depict what you are doing when reading with complete (or even incomplete) attention and comprehension of the meanings involved.

“In essence, the combination of these principles forms the basis of what few of us would ever suspect: a reading circuit that incorporates input from the two hemispheres, four lobes in each hemisphere (frontal, temporal, parietal, and occipital) and all five layers of the brain (from the uppermost telencephalon and adjacent diencephalon below it; to the middle layers of the mesencephalon; to the lower levels of the mesencephalon and myelencephalon).” So anyone who still believes that we use only a tiny portion of our brains hasn’t yet become aware of what we do when we read.

Memory, Attention, Consciousness

November 30, 2014

I’ve just begun reading The Organized Mind: Thinking Straight in the Age of Information Overload by Daniel J. Levitin. I’ve already realized that I should have read this book some time ago, and it is already clear that I am going to recommend it. Usually I do not recommend books until I’ve completed reading them, but I am making an exception in this case. It is already clear that much of the advice will involve transactive memory. Before proceeding with advice providing posts, I feel compelled to write a post on memory, attention, and consciousness. These three topics are central to the healthymemory blog, and although Levitin does not necessarily provide new information, I think that his treatment of these topics deserve special consideration.

Here is how Levitin begins Chapter 2 on How Memory and Attention work, “We live in a world of illusions. We think we are aware of everything going around us. We look out and see an uninterrupted picture of the visual world, composed of thousands of little detailed images. We may know that each of us has a blind spot, but we go on blissfully unaware of where it actually is because our occipital cortex does such a good job of filling in the missing information and hence hiding it from us.

“We attend to objects in the environment partly based on our will (we choose to pay attention to some things), partly based on an alert system that monitors our world for danger, and partly based on our brain’s own vagaries. Our brains come preconfigured to create categories and classifications of things automatically and without our conscious intervention. When the systems we’re trying to set up are in collision with the way our brain automatically categorizes things, we end up losing things, missing appointments, or forgetting to do things we needed to do.”

Regular readers of the healthymemory blog should know that memory is not a passive storage system for data. Rather it is dynamic, guiding our perception, helping us to deal with the present and project into the future. Fundamentally it is a machine for time travel. It is not static, but constantly changing, with the sometimes unfortunate consequent in our being highly confident of faulty recollections. Memories are the product of assemblies of neurons firing. New information, learning, is the result of new cell assemblies being formed. Neurons are living cells that can connect to each other, and they can connect to each other in trillions of different ways. The number of possible brain states that each of us can have is so large that it exceeds the number of known particles in the universe. (I once asked a physicist how they computed this number of known particles and he told me. I would pass this on to you had I not forgotten his answer.)

Attention is critical as there is way too much information to process. So we need to select the information to which we want to attend. Sometimes this selection process itself demands.substantial attention. Moreover, switching attention requires attention, which only exacerbates attentional limitations when multitasking.

Consciousness has been explained as the conversation among these neurons. Levitin has offered the explanation that there are multiple different cell assemblies active at one time. Consciousness is the result of the selection of one of these cell assemblies. In other words, there are multiple trains of thought, and we must choose one of them to ride.

A critical question is how to employ our limited consciousness effectively. One way is the practice of mindfulness meditation to try to achieve a Zen-like focus of living in the moment. This can be accomplished through a regular meditation regimen. However, we should not neglect the short time application of this mindfulness. We need to apply this Zen-like focus when putting things down (your keys, important items), so you’ll remember where you put them. Also do not neglect uses of transactive memory and put notes in planners, on calendars, or in your electronic device so you’re sure you’ll be able to access them.