* I have initiated a new blog for my Brain Manual. You can find it at: brainausersguide.wordpress.com Please bear in mind the topic is a huge one and this is only just the beginning. The brain is so complex it’s going to take a very long time indeed to cover all that is does in any useful detail.
I hope that with your help and input I can start to put together a very basic (though occasionally highly detailed) Manual for the Human Brain that people can read and hopefully use to improve their understanding of what they do and why they do it and will give them choices in how to improve the parts of their lives they may be having difficulties with, which i am quite sure, for the most part, comes down to how they learned to use their brain, or what their brains were taught, via experience, to do.
Potential chapter titles:
- Structure – what the brain is made up of and how it performs its various functions in our body. The various brain regions and sub sections, their locations and what functions they are mostly responsible for controlling/performing/assisting in.
- General Functions – brief synopsis of the brain’s role in everything we do as human beings. Broadly classified as sensory input/output and feedback functions, motor (muscle) function, and associative functioning (the way parts of the brain interconnect with other parts of the brain and body when performing complex tasks).
- Mind. Our Consciousness – our states of awareness and our degree of control over them. Healthy versus unhealthy states of mind.
- The Concept of Self. Being aware of, and identifying with, your ‘self’. Who are we and what makes us the way we are? Does our Self change? Should we have more ‘say’ in what we are, or think we are? Self delusion, personal bias, confirmation bias.
- Brain Psychology.
- Dreaming. Being unconscious. Are dreams ‘real’ – can we tell the difference between a dream state and an aware one? What is real to the brain?
- Meditation. How to gain more control over the way your brain works for you.
- Learning. What are the most effective methods of training the brain, improving our performance in various tasks/functions.
- Memory. Recall and recognition. How are memories created, retained, recalled? what can be done to improve memory/what things interfere with it?
- Sleep and the Brain. How sleep affects brain activity. What are the benefits/costs?
- Hypnosis. Can our brains be fooled (can they not be?) Can another person direct our consciousness without our awareness?
- Addiction. What is the brain’s role in addictive behaviour. Can it be self-regulated effectively?
- Mental health. What is mental health – what is mental unhealth? How can we best maintain a healthy mind?
- Thoughts and rational thinking.
- Creativity and productivity. Can a well-disciplined mind produce truly original creative thoughts/ ideas?
- Communication – with our self; with other ‘Selves’, with other sentient beings, eg. pets, other creatures.
- What is ‘Real’/Reality?
It has always amazed me that despite the fact every single human has a brain, without which we would be incapable of doing a single thing – not even breathing, we generally have such a poor understanding of it; what it is, what it looks like, how it is made up, how we ‘use’ it every second of our lives (often without even being aware of what it is doing) and particularly how each one of us might learn to use it to our greatest human advantage.
There is no manual for a human brain, we simply have trial and error as the most popular way of working out how best to use it. (Some just simply learn how to get it to do a few basic tasks to meet certain personal needs and let it wander off to do whatever it likes the rest of the time).
Our brain is possibly the most complex organism in the known Universe and is capable of almost unlimited potential in our lives. Although relatively small in size, representing around 2% of our total body mass at a little over a kilogram (2-3lb) in weight, it contains some 86 billion neuron cells (+/- 10%) and a similar number of non-neuronal cells. Each neuron may be connected to up to 10,000 other neurons, passing electro-chemical signals to each other via as many as 1,000 trillion synaptic connections, equivalent by some estimates to a computer with a 1 trillion bit per second processor!¹
It literally controls and processes everything we do, everything we are. From before we leave the womb to shortly after we die (or could be pronounced ‘brain dead’ which is a bit of a ‘fuzzy’ term capable of differing interpretation)!
Fig 1. Two diagrams representing a typical human brain – the colours were added to more clearly display areas of our brains that serve mostly one type of function.
Fig 2. A closer to real image of a human brain which is largely pink when living, with red blood flowing through it. Human brains we are most likely to see are generally greyish in colour having no blood and most likely have been stored in a preservative, hence ‘grey’ matter referred to when someone is using their brain.
Although the Cerebrum, which is the main part of the brain we normally can see with all the folds and valleys, is the largest part of our brain it only contains about 20% of the neuron cells, while the large majority – 80% – are contained in the smaller cerebellum region tucked in the back and underneath the cerbrum/cortex. (You can just see it sticking out in Fig 2.)
Chapter 1. Structure
Brain structure is very complex having several ‘layers’ and components and specific regions to which certain body and mental function are attributed. Roughly 50% of the brain comprises of nerve cells called Neurons of which there are 5 main types including interneurons, pyramidal cells including Betz cells, motor neurons (upper and lower motor neurons), and cerebellar Purkinje cells. Betz cells are the largest cells (by size of cell body) in the nervous system.
Of the remaining 50% of brain cells they include:
Glial cells of which there are also 5 main types: astrocytes (including Bergmann glia), oligodendrocytes, ependymal cells (including tanycytes), radial glial cells and microglia. Astrocytes are the largest of the glial cells.
Cerebrospinal fluid acts as a cushion or buffer for the brain, providing basic mechanical and immunological protection to the brain inside the skull. CSF also serves a vital function in cerebral autoregulation of cerebral blood flow. There may be other functions it serves but little experimental documentation currently exists on these.
Blood cells and blood vessels including a specific form of white blood cells known as Mast cells.
Purkinje cells form the heart of the cerebellar circuit, and their large size and distinctive activity patterns have made it relatively easy to study their response patterns in behaving animals using extracellular recording techniques. Purkinje cells normally emit action potentials at a high rate even in the absence of the synaptic input. In awake, behaving animals, mean rates averaging around 40 Hz are typical. The spike trains show a mixture of what are called simple and complex spikes. A simple spike is a single action potential followed by a refractory period of about 10 ms; a complex spike is a stereotyped sequence of action potentials with very short inter-spike intervals and declining amplitudes. Physiological studies have shown that complex spikes (which occur at baseline rates around 1 Hz and never at rates much higher than 10 Hz) are reliably associated with climbing fiber activation, while simple spikes are produced by a combination of baseline activity and parallel fiber input. Complex spikes are often followed by a pause of several hundred milliseconds during which simple spike activity is suppressed
Arguably the cells of most interest in the brain are the neurons. Brain activity is made possible by the interconnections of neurons and their release of neurotransmitters in response to nerve impulses. The whole circuitry is driven by the process of neurotransmission. Neurons can transmit and receive electrochemical signals to/from other neurons via a synapse, which allows multiple neurons to form neural pathways, neural circuits, and large elaborate network systems, in some ways comparable to computer networks. Unlike a computer however where the circuits are pre-designed and of a fixed nature, neural networks are adaptable and are able to change continually, some being created, some reinforced and some reduced/reprogrammed.
The brain uses both release of chemicals and electric current to allow the transfer of signals between neurons; there are chemicals that inhibit an action as well as chemicals that stimulate an action and the brain relies upon maintaining the correct balance between these activities and also getting the timing right. These chemical neurotransmitters include dopamine, serotonin, GABA, glutamate, and acetylcholine. Neuron electrical activity depends upon concentrations of surrounding chemical ion solutions of such elements as sodium, potassium, chloride, and calcium.
That’s a ‘brief’ description of what the brain is made up of and the sort of internal activity it generally comprises. Let’s now look at the physical structure – where all the various internal structures are located, and learn a few key terms and a short coverage on what roles each one serves.
Our brain is built up from 3 main groups of structures. They are the Cerebrum, the Cerebellum and the Brain Stem. The Cerebrum is the largest part of the brain, consisting of the outer cerebral cortex as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. In the human brain, the cerebrum is the uppermost region of the central nervous system.. The cerebral cortex is the outer layer of neural tissue of the cerebrum of the brain, in humans and other mammals.
It is separated into two cortices, by the longitudinal fissure that divides the cerebrum into the left and right cerebral hemispheres. The two hemispheres are joined beneath the cortex by the corpus callosum. The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in memory, attention, perception, awareness, thought, language, and consciousness. The cerebral cortex is an outer layer of ‘grey’ matter, covering the core of white matter. The cortex is split into the neocortex and the much smaller allocortex. The neocortex is made up of six neuronal layers, while the allocortex has three or four. Each hemisphere is conventionally divided into four lobes² – the frontal, temporal, parietal, and occipital lobes as per Fig 1 above.
The frontal lobe is associated with executive functions including self-control, planning, reasoning, and abstract thought, while the occipital lobe is dedicated to vision. Within each lobe, cortical areas are associated with specific functions, such as the sensory, motor and association regions. Although the left and right hemispheres are broadly similar in shape and function, some functions are associated with one side, such as language in the left and visual-spatial ability in the right. The hemispheres are connected by commissural nerve tracts, the largest being the corpus callosum.
The cortex directs the conscious or volitional motor functions of the body. These functions originate within the primary motor cortex and other frontal lobe motor areas where actions are planned.
As the name suggests the sensory areas of the Cortex deal with information received from our (5) senses; The senses of sight, hearing, and touch are served by the primary visual cortex, primary auditory cortex and primary somatosensory cortex respectively.
The association areas are the parts of the cerebral cortex that do not belong to the primary regions. They function to produce a meaningful perceptual experience of the world, enable us to interact effectively, and support abstract thinking and language. The parietal, temporal, and occipital lobes – all located in the posterior part of the cortex – integrate sensory information and information stored in memory. The frontal lobe or prefrontal association complex is involved in planning actions and movement, as well as abstract thought. Globally, the association areas are organized as distributed networks. Each network connects areas distributed across widely spaced regions of the cortex. Distinct networks are positioned adjacent to one another yielding a complex series of interwoven networks.
Chapter 2. General Functions.
To most people our brain is just the lump of matter encased in our skull – it’s a single organ. The reality however, is that as shown in the previous chapter our ‘one’ brain has many components and can simultaneously perform many different functions – it acts like a number of different organs.
It’s most basic functions are the ones we need to keep our body alive and there are quite a number of individual ones that have to be co-ordinated and adequate resources applied to ensure they all work effectively together. Even if our human body is almost totally immobile our brain has to control the operation of:
Our breathing – to ensure our lungs draw in Air for the Oxygen gas essential for supplying energy to our cells via our blood circulation system that the brain controls and simultaneously ensures the same blood extracts waste from our cells and transfers it through the lungs as Carbon Dioxide back into the air. (This is known as the Respiration System).
Our digestion – besides the oxygen we need to live we also need to consume both food and water, otherwise known as eating and drinking which our gut breaks down so we can absorb the required nutrients our cells need to grow and maintain themselves; in addition we also need to remove waste products other than carbon dioxide from our bodies, both solid and liquid, through the Digestive System.
Our balance – whether we are standing on 2 legs, sitting down, on all fours or lying down we need to accurately determine our body position in space and activate muscles and other parts of our body to help us remain in or move from that position. The primary method of determining this is from input from a tiny organs in our inner ears, the semi-circular canals, which are part of the Vestibular System.
Our blood circulation – our body’s cells need oxygen and nutrients to survive and the delivery system is the blood and blood vessels which are fed by our pumping mechanism, the Heart. This forms the Circulatory system.
Chapter 3. Mind.
Chapter 4. The Concept Of Self.
Chapter 5. Brain Psychology.
² – Brain research is an ongoing and fluid study and new discoveries are constantly updating older ideas and pictures of the brain. Some research indicated there might be 5 or 6 lobes per hemisphere.