THE SENSATIONAL
BRAIN
What is it and how it works Dr Veronica Miller
BRAIN
Y
IntroducIng the braIn
our heart beats , fingers feel , muscles move , eyes see , ears hear , toes tingle and tongue tastes . A four year old wouldn ’ t need a degree in anatomy to tell you that . From day one we can feel our body in action . A quick blink tells us our eyes synthesise sight . A nibble on a chilli pepper tells us our tongues taste . And a shock to the system sets our hearts thumping , showing us what makes blood shoot about our bodies .
But , if you ask a four-year old what their brain does , they ’ ll probably just scratch their heads in wonder . And perhaps you would too .
Billions of electrical impulses are produced every millisecond in our brains . These actively motivate our minds , move our limbs , yet , apart from the odd headache , you may wonder how we know the brain is working and what exactly it does ? fake ; if you show people a series of pictures showing smilers most of us will pick out the fake from the true smiles . With age we learn that facial expressions can be faked to some extent , but blushing and shaking with nerves are less likely to be faked . These subtle and not-sosubtle clues about emotional states are all registered within the brain .
Three , two , one , go
So despite the fact that our spines tingle and hearts race with excitement , it ’ s actually the brain that controls our emotions . Inside our brains are pleasure pain and fear centres in our limbic and cortical brain areas . You could rank our emotional responses , much in the way that the James-Lange theory does into three different levels .
Firstly we have the autonomic system response . The primary autonomic areas in the brain are the brainstem and the hypothalamus . The brainstem mediates our heart rate , breathing sweating and eyes dilating and is the first area of the brain to be activated in emotional situations . Then messages are fired from it to the hypothalamus to trigger the release of different chemicals into the bloodstream preparing us for an emotional response . James Olds and Peter Milner discovered this in 1954 after finding that electrical
A cross section through the brain stem .
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To understand the brain it ’ s not enough to know a few physical details , important as they might be , because each is in reality just part of the whole . In many ways this is like an ancient story from India about the “ Three blind men and an elephant .”
In this story , a rajah was asked to settle a dispute in his court between those who believed life was eternal and those who did not . In order to find out how the men could come to a firm conclusion on such an important matter , the rajah gathered six blind men and sent them to the jungle to encounter an elephant . They were told to return to the court and describe the elephant to him .
The first blind man laid his hands on the elephant ’ s side and described the elephant to the rajah as being like a wall . The second man felt the elephant ’ s sharp tusks and told the rajah that the elephant was more like a spear . The third felt the elephant ’ s trunk and said that the elephant was snake-like . The fourth felt the elephant ’ s wrinkly knees and stimulation of the hypothalamus in animals produced euphoric , rage or attack behaviours . Secondly , and up a level , we have the limbic system consisting of the hippocampus and amygdala . The amygdala controls our fear and anxiety responses , and the hippocampus makes short term memories , so that we know what to do next time the emotional response is needed . If you stop the hippocampus and amygdala working in animals by cutting off their blood supply , you find that the animals become very docile and lack normal emotional responses , such as fear or anger .
The third tier of emotional cake is the input to our cortex and output generated by it to the limbic and autonomic areas via the relay station in the thalamus to help us make informed decisions as to how to respond to the emotional situation . Whether to fight or take flight .
Eye sense fear and I feel afraid
BRAIN
Fear can be fast and slow — an instantaneous fright when somebody jumps out at you as you walk along a darkened corridor , and a longer-lasting feeling of unease as you walk home at night-time along a dark road . Quick fears are processed within seconds in our bodies and are mainly processed via the autonomic and limbic systems .
The sensaTional brain
Dr Veronica Miller explains what goes on inside our heads — what makes us smart , why we get emotional , how memories are stored and what happens when things go wrong .
Available from www . sciencespin . com and indepedent bookshops .
Full colour hardback € 25 .
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