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The brain
explained
Understanding how a healthy human brain functions can be a huge help in better appreciating the impact that dementia can have
Cerebral cortex
What we are looking at is the cerebral cortex. This is the outermost layer of the brain, otherwise known as grey matter. Although it is only a few millimetres thick, it accounts for about half of the weight of the brain.
The cortex has a folded surface, which, if flattened out, would be much larger than it looks when folded. The folds allow the cortex to accommodate a large surface area in the limited space in the skull. This allows more neurons to be packed into the cortex and maximises the brain’s processing power.
Brain power
Neurons – otherwise known as nerve cells – are the cells of the brain. They pass electrical impulses with the help of chemicals called neurotransmitters, relaying information across the brain and from the brain to the body and back again.
Below the cortex are various sub-cortical structures which are involved in many different complex activities. We will mainly focus on the cortex as this is primarily what is affected by dementia.
Sections of the brain
It is widely understood that different regions of the brain are involved in specific functions but we also know that the brain is a highly complex organ with an elaborate interaction of parts. The cortex is divided into two halves called hemispheres:
The left hemisphere tends to be thought of as our ‘computer’ brain, a centre of logic and facts. Most dementias affect the left hemisphere first.
Our right hemisphere is more about our emotional memories and creative abilities. Right hemisphere skills may be retained for longer
Each hemisphere contains 4 lobes, connected to each other by a superhighway of neurons called the corpus callosum. So altogether we have 8 lobes, 4 on the right and 4 on the left. The lobes of the brain are:
The occipital lobe is the primary visual centre and it works in tandem with the eye to help us interpret what the eyes are looking at. The occipital lobe helps us judge distance, speed, depth and controls our field of vision.
Next to the occipital lobe lies the parietal lobe, which plays a role in developing reading skills. It’s also the part of the cortex that interprets sensation such as touch, temperature, pain and proprioception or the position of the body in space.
The temporal lobe contains the primary auditory cortex, which sits at the side next to the ear. This is where the brain makes sense of the sounds the ears capture, such as discerning birdsong from speech. The temporal lobe is heavily involved in understanding language and speaking and is where we store knowledge about objects, for example understanding what a fork is and how it’s used and knowing how it is different from a knife.
Finally, we have one of our memory centres deep in the temporal lobe on the border of the limbic system which we will touch on later. A small structure called the hippocampus, is involved in memory, especially recalling new information but it also helps in reconstructing longer term memories
The frontal lobe has a role in controlling our impulses and social behaviour. It’s what stops us saying out loud what we may be thinking if we know it would hurt someone’s feelings. It also helps us to be empathetic and put ourselves in someone else’s shoes. In addition, the frontal lobe is our centre of executive functioning. This includes cognitive skills such as planning, organising, problem solving, concentrating, anticipating, reflecting etc.
Sub-cortical brain
Beneath the cortex lies the limbic system which is a set of structures in the brain that deal with emotions and memory. The amygdala is also part of the limbic system and is one of the structures in the brain that processes emotion. It also helps us to assess threats, manage fear and drives our ‘fight or flight’ reactions.
More about the brain
You can find plenty more resources about the brain in this section of the site. Including a video version of this tour of the brain.
This tour of the brain is best viewed on large screens where you can explore a 3D model of the human brain
Scroll down to continue on mobile
Cerebral cortex
The cerebral cortex is the outermost layer of the brain, otherwise known as grey matter. Although it is only a few millimetres thick, it accounts for about half of the weight of the brain.
The cortex has a folded surface, which, if flattened out, would be much larger than it looks when folded. The folds allow the cortex to accommodate a large surface area in the limited space in the skull. This allows more neurons to be packed into the cortex and maximises the brain’s processing power.
Brain power
Neurons – otherwise known as nerve cells – are the cells of the brain. They pass electrical impulses with the help of chemicals called neurotransmitters, relaying information across the brain and from the brain to the body and back again.
Below the cortex are various sub-cortical structures which are involved in many different complex activities. We will mainly focus on the cortex as this is primarily what is affected by dementia.
Sections of the brain
It is widely understood that different regions of the brain are involved in specific functions but we also know that the brain is a highly complex organ with an elaborate interaction of parts. The cortex is divided into two halves called hemispheres.
The left hemisphere
The left hemisphere tends to be thought of as our ‘computer’ brain, a centre of logic and facts. Most dementias affect the left hemisphere first.
The right hemisphere
The right hemisphere is more about our emotional memories and creative abilities. Right hemisphere skills may be retained for longer
Each hemisphere contains 4 lobes, connected to each other by a superhighway of neurons called the corpus callosum. So altogether we have 8 lobes, 4 on the right and 4 on the left. The lobes of the brain are:
The occipital lobe
The occipital lobe is the primary visual centre and it works in tandem with the eye to help us interpret what the eyes are looking at. The occipital lobe helps us judge distance, speed, depth and controls our field of vision.
The parietal lobe
Next to the occipital lobe lies the parietal lobe, which plays a role in developing reading skills. It’s also the part of the cortex that interprets sensation such as touch, temperature, pain and proprioception or the position of the body in space.
The temporal lobe
The temporal lobe contains the primary auditory cortex, which sits at the side next to the ear. This is where the brain makes sense of the sounds the ears capture, such as discerning birdsong from speech. The temporal lobe is heavily involved in understanding language and speaking and is where we store knowledge about objects, for example understanding what a fork is and how it’s used and knowing how it is different from a knife.
Finally, we have one of our memory centres deep in the temporal lobe on the border of the limbic system which we will touch on later. A small structure called the hippocampus, is involved in memory, especially recalling new information but it also helps in reconstructing longer term memories
The frontal lobe
The frontal lobe has a role in controlling our impulses and social behaviour. It’s what stops us saying out loud what we may be thinking if we know it would hurt someone’s feelings. It also helps us to be empathetic and put ourselves in someone else’s shoes. In addition, the frontal lobe is our centre of executive functioning. This includes cognitive skills such as planning, organising, problem solving, concentrating, anticipating, reflecting etc.
Sub-cortical brain
Beneath the cortex lies the limbic system which is a set of structures in the brain that deal with emotions and memory. The amygdala is also part of the limbic system and is one of the structures in the brain that processes emotion. It also helps us to assess threats, manage fear and drives our ‘fight or flight’ reactions.
More about the brain
You can find plenty more resources about the brain in this section of the site. Including a video version of this tour of the brain.