Introducing: Your Brain!
The brain is your body’s control centre. It is in charge of everything you think, say and do! But how does the brain work? What does it look like? How can we link the brain to behaviour?
Your brain: A number of working parts
Your brain, along with your spinal cord forms your central nervous system (CNS). The central nervous system interacts with the peripheral nervous system which receives sensory input - sends it to your CNS for processing - and then awakens muscles in response to instructions from the brain. Your brain itself is made of a number of parts. The ‘thinking and doing’ part of your brain is called the cerebrum and this is the part of your brain that you often see depicted in the media (like the image below).The cerebellum, at the back of the brain, is largely responsible for balance and coordinating movement - although recent research has discovered that this largely overlooked area may also be involved in executive function, visual spatial processing, linguistic skills and emotional regulation. The brainstem connects the brain to the spinal cord, and consists of the medulla oblongata, pons and midbrain. The brainstem controls basic body functions like breathing, swallowing and heart rate.
Image credit: Laura Marsh
Your brain: A buzzing centre of activity
The cerebrum is the part of the brain the neuropsychologists and cognitive neuroscientists are most interested in. It is made up of soft tissues that are folded into a series of grooves and ridges - kind of like wrinkles! It has two sides that are known as the right and left hemisphere. Each hemisphere controls motor activity on the opposite side of the body, and can be divided into four sections - called lobes - that are traditionally responsible for different functions.
The frontal lobe - often referred to as the air-traffic control system - helps us make decisions and solve problems. The parietal lobe deals with sensory processing, the occipital lobe is in charge of visual processing, and the temporal lobe is important for memory and language. It must be noted, however, that although the occipital lobe is important for vision and the frontal lobe is important for attention - you pull on many different brain areas to complete even the most simple of tasks. Think about all of the cognitive processing involved in riding a bike for example. Motor areas are called upon to move pedals and steer, while the cerebellum is required to coordinate pedalling and maintain balance. Visual processing and attention-related areas are important in detecting potholes, as the frontal lobe helps to navigate around them! At the same time, the brainstem would be concerned with increasing heart rate and breathing in response to the intensity of the exercise.
A recent review of brain imaging studies by Gilmore and colleagues has demonstrated that the brain changes rapidly during development, on both structural and functional levels. Neuroscientists and neuropsychologists use lots of ways to measure the brain-behaviour relationship including event related potential (ERP) and functional magnetic resonance imaging (fMRI). ERPs are small voltages - or brain waves - generated in the brain in response to, or stimulated by, a ‘stimulus’ such as a picture of a face. ERP captures the activity of one or a group of neurons related to a specific sensory or cognitive process like visual attention. fMRI is a brain scan that records changes in blood flow within the brain to identify activated areas during a given task. Remembering our example of riding a bike, below is an fMRI showing brain activity within motor regions and the cerebellum during foot movement.
Image credit: Living Art Enterprises
Your brain: An electrochemical party
Your brain works like a small computer. It takes in information from the senses, processes it, and sends messages back to the rest of the body. Messages are sent to and from the brain by brain cells called neurons. Neurons are cells that look like trees with lots of branches that go in different directions. There are billions of them all around your body, of many different shapes and sizes. The longest neurons travel from the bottom of your spine all the way down to your toes! Neurons comprise of three main parts (cell body, axon and dendrites) and are separated by tiny gaps called synapses. Electrical signals are received by dendrites, travel to the cell body, and continue down the axon until they reach a synapse. Once a signal reaches the end of a neuron it triggers the release of chemicals called neurotransmitters. Neurotransmitters float across the synapse to a neighbouring neuron, which contains receptors that catch them. An electrical signal will then flow down this new neuron to another neighbouring neuron and so on. This is how neurons ‘talk’ to each other!
Image credit: KhanAcademy.org
Neurons are protected and supported by different brain cells. Ependymal cells play a key role in the production of cerebrospinal fluid - the cushion between the brain and the skull. Microglia clean debris from dying neurons, as astrocytes maintain a barrier between brain tissue and blood. Oligodendrocytes produce myelin sheath, which surrounds axons and speeds up signal transmission. Collectively these cells are known as glial cells.
Certain neurons group together to make networks that carry out a specific function when activated. In order to read this blog post, your brain has activated neurons of both visual and language networks. Right now the neurons in your visual system are translating straight and curved lines into letters and grouping these shapes into meaningful information: words. At the same time, your language system is deciding what these words mean! You are also focusing on reading this blog while ignoring everything else going on around you - but how? Find out next time when Jen will be explaining how our brain pays attention. In the meantime, don’t forget to follow us on Twitter and Facebook for all the latest news from our lab!
If you would like to learn more about brain structure and function, then here are some useful resources:
How the Brain Works http://howthebrainworks.science/
Youtube: CrashCourse https://www.youtube.com/playlist?list=PL8dPuuaLjXtOAKed_MxxWBNaPno5h3Zs8
Crossman, A. R., & Neary, D. (2015). Neuroanatomy: an illustrated colour text (5th ed.). Edinburgh: Churchill Livingstone Elsevier.
Gilmore, J. H., Knickmeyer, R. C., & Gao, W. (2018). Imaging structural and functional brain development in early childhood. Nature Reviews Neuroscience, 19(3), 123. https://www.nature.com/articles/nrn.2018.1
Schmahmann, J. D. (2019). The cerebellum and cognition. Neuroscience Letters, 688, 62-75. https://www.sciencedirect.com/science/article/abs/pii/S0304394018304671
