PHYSIOLOGICAL APPROACH BACKGROUND AND CONTEXT Core Study: Sperry (1968)

So… which ‘side’ are you on? PLEASE REMEMBER THIS IS TONGUE IN CHEEK! Have a go at the ‘which side’ quiz

So… which ‘side’ are you on? PLEASE REMEMBER THIS IS TONGUE IN CHEEK! 1.Give yourself one point for each time you answered "A" for questions: 1, 2, 3, 7, 8, 9, 13, 14, 15, 19, 20, Give yourself one point for each time you answered "B" for questions: 4,5, 6, 10, 11, 12, 16, 17, Add all points. Totals imply: 0-4: strong left brain 5-8: moderate left brain 9-13: middle brain 14-16: moderate right brain 17-21: strong right brain

Extracts from Guardian Article: Amy Novotney theguardian.com, Saturday 16 November GMT Amy Novotney theguardian.com In a new two-year study published in the journal Plos One, University of Utah neuroscientists scanned the brains of more than 1,000 people, ages 7 to 29, while they were lying quietly or reading, measuring their functional lateralization – the specific mental processes taking place on each side of the brain. They broke the brain into 7,000 regions, and while they did uncover patterns for why a brain connection might be strongly left or right-lateralized, they found no evidence that the study participants had a stronger left or right-sided brain network.Plos One

Extracts from Guardian Article: “It's absolutely true that some brain functions occur in one or the other side of the brain, language tends to be on the left, attention more on the right. But the brain isn't as clear-cut as the myth makes it out to be. For example, the right hemisphere is involved in processing some aspects of language, such as intonation and emphasis.” Jeff Anderson, University of Utah

Extracts from Guardian Article: The neuroscience community has never accepted the idea of 'left-dominant' or 'right-dominant' personality types. Lesion studies don't support it, and the truth is that it would be highly inefficient for one half of the brain to consistently be more active than the other.neuroscience Jeff Anderson, University of Utah

Background Truth, half-truth or myth? Using your iPads, see what you can find out about the following statements: Remember – try to use websites which cite evidence True/false/half-truth? Language is lateralised to (specialised to) the left side of the brain. People are either right or left ‘brained’. The right side of our brain controls the left side of our body.

Background For a long time, the concept of ‘left brain’ and ‘right brain’ has endured While we now know that it isn’t that simple, and that both sides of our brain are involved in the majority of things we do, there is some evidence of lateralisation of function of some abilities It is also true that that information from the left visual field, goes to the right of the brain and vice versa The left side of the brain controls the right side of the body (contralateral)

Lateralisation of Function Language: Broca’s area – responsible for speech production Wernicke’s area – reposible for speech comprehension These areas are located in the left hemisphere for the majority of people Damage to these areas may lead to aphasia or an inability to produce language

The Corpus Callosum

A large band of axons that link the two hemispheres. It is the largest of the commissures in the brain but is not the only one. It is located deep within the brain and is approximately 10cm long and ¾ cm wide. It facilitates the transfer of information from one cortical hemisphere to another. In the early days people did not believe that it had a function but thought that it was just there to keep the two hemispheres together.

The brain is divided into two halves: The left and right hemispheres In most people the opposite side of the brain controls the opposite side of the body Hold up the arm that is controlled by the right hemisphere of your brain The two hemispheres are joined by the corpus callosum

Commissurotomies Given to patients with severe epilepsy for whom drugs had not been effective First performed by Wilder Penfield Involve the severing of the corpus callosum to prevent neural messages passing from one hemisphere to another. Effectively separating the two hemispheres and thus ‘splitting’ the brain in half Appeared to be no side effects Sperry had been performing similar operations on animals and felt that there were some side effects that were not obviously visible in day-to-day life. As a result of his work on animals, who had demonstrated behavioural changes following commissurotomies, Sperry believed in lateralisation of function, although up until this point it had not been demonstrated in humans With the patients permission, Sperry decided to perform some experiments on patients who had undergone commissurotomies.

Vision and our brain: Information from the Left Visual Field ends up in the ______ Hemisphere. Information from the Right Visual Field ends up in the ______ Hemisphere. LVF RVF

Ideas about lateralisation of function: As mentioned earlier, though both sides of your brain are involved in most things, there are certain functions which seem to be more reliant on one hemisphere than the other. This is true in all people and it is unlikely that you are ‘left’ or ‘right’ brained The supposition: The left half of the brain is specialised for language linguistic expression both symbolic and logical The right half of the brain is specialised for perception visuospatial and artistic

In order for humans to function properly, the two sides of the brain must be able to communicate The corpus callosum gives each hemisphere access to the other The corpus callosum has been severed in some case of severe epilepsy, in order to stop their seizures The procedure is known as a commissurotomy Most patients suffered very few side effects, however, the one that was observed was particularly interesting…

SPLIT-BRAIN PATIENT ‘JOE’ VIDEO OM/WATCH?V=RFGTGIL7V EY

What was interesting/surprising about the video? What part of Joe’s brain was severed? What COULD Joe do to describe the object? What does this example suggest to us about the brain?

ROGER SPERRY Neuropsychologist 1950s – undertook research which involved splitting the brains of cats and monkeys (ethical?) He discovered that it was possible to teach one hemisphere a task, while the other remained unaware This led to the idea that the two hemispheres of the brain were separate modules, not one unified whole

HOMEWORK APRC SPERRY’S STUDY DUE NEXT LESSON Challenge yourself: use the original journal article