We can literally see how the circuit board of the mind – this amazing machine comprised of billions of nerve cells, with trillions of connections between them – shifts and changes as we make decisions and experience the world around us. Dr. Hannah Critchlow, a British author, neuroscientist, and fellow of Magdalene College Cambridge, who is at the frontline of neuroscience writes: “We are learning about the brain at an exponential rate now – there are as many as five to ten thousand new research papers coming out each month. We still have a lot to learn of course, and there are still major problems, as we can see with mental health, but we are discovering the real underpinnings of the brain’s operation and this information will help us to better treat some of the debilitation conditions of the mind. UT South western medical college center identified more than one hundred genes linked to memory which are helping us to unlock many of the mysteries behind the body’s most complex organ and are leading to advancements in the treatments of various brain disorders.
As part of the body’s nervous system, the brain coordinates all of the body’s functions. Weighing in at around 1.4 kg, the human brain is more complex than any other known structure in the universe and is responsible for all of the body’s functions and learning. It is comprised of 4 regions:
Cerebrum: ¾ of the brain’s volume – controls higher functions such as learning, reasoning, speech and senses (sight and hearing).
Cerebellum: Coordinates muscle movements (balance and posture).
Brain stem: Sensory information, movement, auditory and visual processing – the motor and sensory pathways responsible for cardiac activity, respiration, digestion and sleep.
Diencephalon: Made up of the thalamus, hypothalamus and pituitary gland – these regulate sensations, control weight, energy and instinctual behaviors.
The human brain is a learning machine. Thanks to a phenomenon called neuroplasticity, the brain learns in a range of ways and many different circumstances, including in the classroom. Neuroplasticity is central to learning. It is essential to remember that learning is a function of memory encoding and consolidation, which, in turn, are processes that change the brain physically. We refer to the brain as being ‘plastic’, because it can change at the cellular level (mostly at the connections between neurons i.e. the synaptic gaps) by creating and reinforcing neural networks. The brain discards, retains and changes information in response to new and repeated experiences. We learn through repetition e.g. when children learn to tie their shoes, they repeatedly practice the steps. In so doing, the associated neurons repeatedly activate in sequence, strengthening the circuit of connected neurons each time. Practice results in the establishment of a ‘shoe-tying’ network. Through neuroplasticity, the brain is molded by experience to reshape and reorganize itself so that we awake with a ‘new’ brain each morning. Whether implicitly or explicitly, neuroplasticity must be a central concept when we think about or discuss learning and memory.
Stages of memory. McLeod suggests that there are three recognized stages of memory development. These are:
Encoding: Memories can be encoded visually (picture), acoustically (sound) or semantically (meaning). Acoustic encoding, as an example, has been found to be effective for short-term memory (STM). Semantic encoding appears to be the principle encoding system for long-term memory (LTM).
Storage: There is a difference in the way we store STM and LTM. We do know that if we ‘chunk’ information together, we can store a lot more in our STM.
Retrieval: Data becomes a memory if we can retrieve it. Our STM and LTM retrieval is very different – STM are stored and retrieved sequentially, while LTM is retrieved by association.
Neurologically, memories are formed when experience is encoded through patterns, whereby cells interact with each other. Almost 20 years ago, scientists at the University of California discovered that brain cells could form connections, temporary and permanent, in response to stimuli. This was the first evidence that the brain could change structurally, influencing how we store and retrieve memory. This discovery proved what scientists had suspected for some time. The important discovery also noted the link between the stimulation of cells, and the creation of a memory.
The researchers found that actin (a protein) inside cells could be stimulated to move toward neurons to which they are connected. Activity in the first cell prompted movement of actin in neighboring neurons. This temporary movement is quite normal, and the activation would last up five minutes, and then disappear quickly. However, they found that if the original cell was stimulated repeatedly (in this case, four times) within an hour, the synapse would physically split, producing new synapses. This potentially produces a permanent change.
The key finding here is that we can induce or consolidate memory through repetition or exposure to experience. We also know that new memories can be quite unstable, but become more ‘consolidated’ over time. This occurs physiologically, through an interaction between glutamate release, protein synthesis, and neuron growth and rearrangement.
Sensory Memory: Takes information from the environment through the human senses (sight, hearing, touch, taste and smell) – stored for a very short time from 0.5 seconds to 4 seconds.
Working Memory: Working memory (WM) is a system responsible for retaining and using memories. This is what you are conscious of, or what you are thinking about at any given moment. Only a small amount of information can be processed in the working memory at one time, anywhere from 5-9 bits of information depending on the research you follow. This is stored for about five to 20 seconds unless we actively try to remember information by repeating it. The STM is a sub-system of WM but its function is to briefly retain information. If additional processing is required, the memories are passed to WM or long term memory (LTM) as appropriate.
Long Term Memory: We hold all our memories in here. The goal of learning is to move information here so we can use it later when we need it. LTM can be explicit and implicit. For memories to become long term memories, they need to be retrieved regularly. Unlike sensory and working memory, long-term memory capacity is unlimited.
For learning to be achieved, three processes need to occur:
Attention: to begin with, a student must pay attention and focus.
Encoding: Learners connect new information to what they already know.
Retrieval: Taking information out of long-term memory and into our conscious working memory – the more times you retrieve something from your long term memory, the easier it becomes. People who have been tested on material are more likely to remember it later, and apply it, than those who only study the material.