Brain Stories: More Facts

Dyslexia is a specific learning disability characterized by difficulties in learning to read. Testing for dyslexia is complex and a variety of different symptoms can be observed. Children and adults with a diagnosis of dyslexia commonly struggle with reading, writing, and spelling. There is no single sign for all people with dyslexia. Research shows that people with dyslexia have difficulty decoding written words, often relating to the mapping of sounds to letters. Although individuals with dyslexia may reverse letters when reading and spelling, this is also relatively common in typically developing readers. Overall, a diagnosis of dyslexia is therefore complex and takes into account a multitude of factors, including genetic risk, responsiveness to intervention, and better listening comprehension ability relative to reading comprehension ability.

The human brain is result of many complex factors influencing each other. It’s always an interplay of genetic and environmental variables that influence brain function, structure and thus our behaviors, perceptions and interpretations.

The development of the human brain, including its mental capacities, is therefore shaped by biological variables as well as learning and experience. Genes strongly determine when and how the brain and individual brain regions develop. Experience and learning, on the other hand, most strongly influence the effectiveness of the corresponding brain networks, behaviors and systems. In the end, genes, environment and the interaction between both are important.

Individuals cannot be differentiated based on using either side of their brains more heavily. Most activities are linked to activity across the whole brain and thus across both brain hemispheres, especially the execution of cognitive tasks. Thetraditional concept of “localizationism” from the last 1800s has shifted to complex neuronal networks throughout the brain and neuroplasticity. For instance, even though the left hemisphere shows dominance for processing language, the right hemisphere is responsible for certain aspects of language processing. The left hemisphere is dominant, since activity in the right is being suppressed. This is only possible because both hemispheres work together. In sum, every task requires the functioning and coordination of both hemispheres. Thus, people cannot be categorized as left-brained or right-brained.

The birth and death of brain cells (called neurons) is a normal, and necessary, part of brain development. During early brain development, neural connections and neurons rapidly appear, creating a structure with more neurons and connections than the individual needs in adult life. The overproduction of these neurons is balanced out through programmed cell death (called apoptosis). It was once thought that adult brains were unable to generate new brain cells. However, research shows that new cells are produced for a long time. For example, in a part of the brain called the hippocampus, 700 new neurons are added each day in adult humans, with some decline during aging.

Male and female bodies, including their brains, develop at different rates. For instance, females achieve earlier onset of puberty and attainment of adult height, which parallels development of the brain. Females reach maximum brain volume approximately 2 years earlier than males (at age 10.5 on average, compared to age 12.5 in males). Overall, the brains of boys and girls develop at different speeds, as well as in different ways due to anatomical, functional, and biochemical differences. However, while differences are important in understanding known sex-prevalences and manifestations of different psychopathologies, there are on average more similarities than differences amongst the brains of boys and girls. Most importantly, these do not reflect on relative capacities.

Learning occurs through the formation of new connections between already existing brain cells, not by the addition of new brain cells. For example, mathematics practice has been shown to associate with anatomical changes in brain areas that play a role in numerical processing and visuo-spatial ability. These changes are even more pronounced among mathematical experts, who have been shown to have an extended network of brain activation. Similarly, musical practice has been shown to increase the activity of brain cells in sensory and motor regions. Musical practice therefore leads to more connections between these brain cells and therefore a greater connectivity between sensory and motor regions in the brain. Synapses are the part of connection and communication between two neurons. An increase in successful connection, equals an increase in synapses. Learning is thus due to an increase in synapses in the brain.

Learning is thought to occur through the development and strengthening of connections between brain cells. While we develop, grow and learn, new connections are formed and unneeded connections are eliminated. Connections that are used a lot are strengthened. When we learn new things, new connections called synapses form between the brain cells. Brain cells that become active together are more likely to form a connection. These new connections, or modifications, in the brain are therefore associated with learning. For example, musical practice has been shown to increase the activity of brain cells in sensory and motor regions. Musical practice therefore leads to more synapses between these brain cells and therefore a greater connectivity between sensory and motor regions in the brain.

Mental illnesses include health conditions that change a person’s feelings, thoughts or behavior and which cause significant distress and impact everyday life. Many different diagnoses exist. Mental illness is associated with changes in the structure, function or chemistry of the brain. While there are some brain diseases that are not characterized as mental illness, the lines are somewhat blurry. All mental illnesses have been demonstrated to have some biological associations (e.g., brain, genetics or other biological factors).

The human brain is divided into two hemispheres: right and left. Both hemispheres play a critical role in behavior. While each hemisphere of the brain controls movement and feeling in the opposite half of the body, the two hemispheres work together through the corpus callosum which is composed of approximately 200 million nerve fibers. The corpus callosum is somewhat like a bridge between the two hemispheres. Most activities are linked to activity across the whole brain and thus across both brain hemispheres, especially the execution of complex cognitive tasks. The traditional concept of “localizationism” from the last 1800s has shifted to complex neuronal networks throughout the brain and neuroplasticity.

Brain development is a protracted process, reaching a peak only around late adolescence and young adulthood, around 22-25 years of age. Brain development therefore does not stop by the time children reach puberty. While brain size is close to those of adults, there are still massive changes associated with development that continue until young adulthood. These include synapse formation, elimination (pruning) and the development of brain networks. Recent research also indicates that until young adulthood protracted brain development for example includes the strengthening and integration of prefrontal-limbic regulatory functions.

When learning, people have preferred learning modalities. However, that does not exclude other modalities to benefit the individual learner. It is important to remember that learning in preferred learning styles does not necessarily lead to better performance. It can, however, make learning more enjoyable for learners.

In fact, "learning styles" is one of the most widespread myths in education. Despite repeated testing of hypotheses relating to learning styles, there is no evidence to date showing that individuals learn better when they receive information in their preferred learning styles. Multiple reviews have reported no evidence of associations between learning-styles based instruction and learning among adults or children. The use of learning styles may actually hinder learning, because individuals may not seek out all opportunities and the propagation of this myth might foster a fixed mindset.

We use our brain 24 hours a day. This means the brain never ceases to function. More specifically, we use all parts of our brain at any given time. However, some functions are localized to specific parts of the brain which may be more “active” relative to others during the performance of that function. Research shows that our brain remains active, even when we sleep. Importantly, during sleep our brains are involved in memory consolidation and reconsolidation, perceptual and motor learning, as well as different forms of embedding complex skill acquisitions. Similarly, even during tasks which involve relaxation, such as meditation, certain regions of the brain associated with attention increase their activity.