Sperry (1968) Hemispheric disconnection and unity in consciousness. Physiological Psychology

Plan for today Recap of Maguire (handout and quiz) Sperry (1968) Context, aim, sample, procedure, results and conclusion Quiz to test knowledge of Sperry.

Recap handout for Maguire

Recap quiz for Maguire

Question 1 – The taxi drivers were A)Male, right-handed and aged B)Male, right-handed and aged C)Male, left-handed and aged D)Female and male, left-handed and aged

Question 2 – What was the average time that the taxi drivers had been licensed for? A)1.5 years B)5.8 years C)10.1 years D)14.3 years

Question 3 – Which of the following is false A)Controls were all male. B)Controls were all right-handed. C)Controls were all healthy. D)Controls attended the laboratory to take part in the experiment.

Question 4 – The method was A)Independent measures quasi experiment B)Repeated measure quasi experiment C)Independent measures laboratory experiment D)Matched pairs laboratory experiment

Question 5 – Which of the following is false A)VBM is an objective technique to examine the brain. B)VBM identifies differences in grey matter in different areas of the brain. C)VBM is a 2D technique. D)Grey matter is associated with higher order thinking.

Question 6 - Which of the following was not a control used for the pixel counting technique A)One person analysed the images. B)The pixel counter did not know if the scan belonged to a taxi driver or someone from the control group. C)Pixel counting is a well-established technique to measure the brain. D)The pixel counter did not know the findings from the VBM technique.

Question 7 – Which two results (for VBM) were found? A)Significantly increased grey matter volume in right and left posterior hippocampi for taxi drivers. B)No differences between hippocampi of taxi drivers and the control group. C)No differences between the brains of taxi drivers and controls other than in their hippocampi. D)Significantly increased grey matter volume in right and left posterior hippocampi for controls.

Question 8 – Pixel count results found A)No significant difference in overall volume of hippocampi between taxi drivers and controls. B)Increased posterior hippocampi in taxi drivers compared to controls. C)Increased anterior and body hippocampi in controls compared to taxi drivers (especially the right). D)All of the above.

Question 9 - Where did Maguire et al conclude that we store mental maps? A)Body of hippocampus B)Anterior of hippocampus C)Posterior of hippocampus

BONUS POINT What did Maguire et al say the LEFT hippocampus stores? Complements its partner by storing memories i.e. people and events that occur in the taxi drivers world (but not necessarily integrating this information into an existing map).

Sperry (1968) Hemispheric disconnection and unity in consciousness. Physiological Psychology

By the end of this session, you will be able to; Describe the function of the corpus callosum. Identify the functions of the left and right hemisphere. Describe the procedure and results of this study. Be able to identify the actions of a ‘split brain’ patient when given different visual cues.

Some background Right hemisphere Left hemisphere Corpus Callosum Our brain is divided into two halves or ……….. Each half is associated with different abilities.

Are you left or right brain dominant?

To score … Give yourself one point for each time you answered "A" for questions: 1, 2, 3, 7, 8, 9, 13, 14, 15, 19, 20, 21. Give yourself one point for each time you answered "B" for questions: 4,5, 6, 10, 11, 12, 16, 17, 18.

Add all the points together … The 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

Lateralisation of function The two hemispheres have different functions from each other.

The brain

The Corpus Callosum  The Corpus Callosum is responsible for communicating messages from the left to the right hemisphere and vice versa.  The CC is made up of a think bundle of nerve fibres called commissural fibres. These are attached to both the R and L hemisphere.

Right and Left hemispheres and the Right and Left sides of the body Which side of the brain controls the left side of the body? Which side of the brain controls the right side of the body?

Class brain

What is a visual field? If you look straightforward everything to the left of your nose is the left visual field and everything to the right is your right visual field. Right Visual Field Left Visual Field

Visual fields – a little more detail HOWEVER! It’s more complex than right eye -> left hemisphere and left eye -> left hemisphere. Information from both eyes goes to both hemispheres. EXAMPLE

Humans are … cross- wired Left Visual Field Right Visual Field Left hemisphere (Language) Right hemisphere (drawing) Left side Right side

Complete brain hemisphere and visual fields worksheet

What do we know about epilepsy? Symptoms can range from; Brief loss of consciousness  severely thrashing the legs and arms uncontrollably (Grand Mal). What is the cause? Abnormal firing of electrical impulses throughout the brain which interrupts normal brain patterns.

During a seizure, electrical impulses pass from one hemisphere of the brain to the other. How (using what we have learned today) might we be able to stop this? Cut the Corpus Callosum This procedure is known as a Split Brain Surgery. (Is carried out as a last resort when medication has failed).

The study AIM - To study the effects of hemispheric disconnection in split-brain patients and to show that each hemisphere has different functions (lateralisation). Participants - 11 ‘split-brain’ patients who had undergone surgery (hemisphere disconnection) for epilepsy – compared to ‘normal’ group.

Sperry’s apparatus Based on Overhead Projector.

Visual apparatus and procedure Participants had one eye covered and asked to stare at a point (fixation point) on a projector screen. Information (picture/word/symbol) was flashed to either the left visual field (LVF) or right visual field (RVF) for 1/10 th second. WHY?? CONTROLS?

Tactile apparatus and procedure Below the screen was a gap so participants could be handed objects or reach into a ‘grab bag’ and touch objects but could not see the objects or his hands. CONTROLS?

Controls The fixation point. Image flashed for 0.1 seconds. Always had one eye covered. Standard pictures/words/symbols shown to each participant. Participants can’t see their hands. Same experimenter used.

Procedure So the participants completed various visual and tactile tasks (with the experimenters attempting to see how the two hemispheres functioned). Participants remained in silence during trials unless asked question by experimenter. WHY?

The study Independent Variable? Dependent Variable? Methodology? Hemisphere disconnection (or not). Performance on visual (sight) and tactile (touch) tasks. Quasi-experiment (no control over IV) and case studies.

Role of right and left hemisphere Use your LEFT and RIGHT signs in response to the following questions …. LEFT RIGHT

Language is processed in which hemisphere? LEFT

The right visual field is controlled by which hemisphere? LEFT

Information from the left hand is sent to which hemisphere for processing? RIGHT

If a patient had a seizure in their left hemisphere, which side of the body might be in danger of paralysis? RIGHT

Information from the right hand is sent to which hemisphere for processing? LEFT

Information from the left visual field is controlled by which hemisphere? RIGHT

Left handed people tend to be which hemisphere dominant? RIGHT

Video of split brain patient h?v=lfGwsAdS9Dc

Different tasks – Visual and Tactile 1)Recognising pictures 2)Matching pictures 3)$ and ? 4)Composite words i.e. KEY CASE 5)Identify objects in hand or find from grab bag. 6)Dual processing task.

Instructions for task You will be given a paragraph explaining 1 method out of the 6. In pairs, you have 10 minutes to do two things 1) Prepare and learn the actions to do a role-play of procedure and results. 1 person is Sperry 1 person is the split-brain participant

2) Prepare an A3 poster (include pictures) to show the procedure and results. As each pair presents their poster and role-plays their procedure and results – the rest of you can complete your procedure and results handout. Instructions for task

Visual - Recognising pictures Stimulus flashed to left side of screen Then flashed to right side P doesn't recognise he has seen it before. If stimulus was flashed to right side again, participant responded as if he had seen it before. Each hemisphere has its own memories - separate consciousness

Visual - Matching pictures Picture projected to Right Visual Field (goes to Left Hemisphere) P can talk and write about it BUT… If the same picture projected to Left Visual Field (goes to Right Hemisphere) P says he saw nothing or just a flash of light. BUT if you then ask the same participant to use his left hand (controlled by Right Hemisphere) to pick up a matching object from a grab bag, he will pick up the object that he has just said he didn’t see. What does this tell us about the right hemisphere?

Right Hemisphere Left Hemisphere LVF RVF What did you see? ? ? ? ? ? ? ? Can you pick out (with your left hand) the object that you saw? EXAMPLE

Right Hemisphere Left Hemisphere LVF RVF What did you see? A happy face! Can you pick out (with your right hand) the object that you saw? ? ? ?

Visual - $ & ? signs If a $ is flashed to the Left Visual Field and a ? to the Right Visual Field …. The participant will draw (using the left hand out of sight) the $ shown to the Left Visual Field but if asked what they had drawn would name the stimulus presented to their Right Visual Field – the ?

Right Hemisphere Left Hemisphere LVF What did you see? A question mark Draw (with your left hand) what you saw. RVF $ ? $? $

Visual - Composite words Two words flashed simultaneously LVFRVF KEYCASE P can say CASE and spell out the word CASE with his right hand P can pick up key from the grab bag with left hand BUT can not say KEY OR join the words together

Touch – Objects in the hands Objects placed in right hand (LH) can be named in speech and writing. Objects placed in left hand (RH) – participants will make wild guesses or seem unaware that they are holding anything at all.

Touch – Objects in the hands continued HOWEVER – if that same object is placed in a grab bag with other objects, the participant could find the original object with his left hand. Participants cannot retrieve the object with their right hand if it was first sensed with their left hand.

Touch – Dual processing If two objects are placed simultaneously one in each hand and then hidden two separate grab bags, both hands can select their own object but will ignore the other hand’s objects.

Visual results summary If shown an object to the RFV, participants can name and describe the object. If shown an object to the LVF, participants cannot name the object but can draw it with their left hand or pick it out of group of objects. If shown an object to both visual fields and given a pen in their left hand, they will name what is in RVF but draw what is in the LFV.

Tactile results summary Objects placed in the right hand (left hemisphere) could be named. Objects placed into the left hand (right hemisphere) could not be named but could be drawn or picked up with their left hand.

Conclusion For split-brain patients One half of the brain does not know what the other half is doing!

Where is our evidence for lateralisation of function?

Evidence for lateralisation of function LEFT HEMISPHERE What is this hemisphere specialised in? Speech and writing. What can this hemisphere do? Can communicate the visual experiences of the right side of the body and the right visual field. RIGHT HEMISPHERE What can’t this hemisphere do? Is mute and cannot speak or write. What can this hemisphere do? Can show non-verbally that mental processes centred around the left side of the body and the left visual field have taken place.

An important question! Why don’t split-brain patients have problems in daily life? In everyday life the patients can overcome their deconnection by … BECAUSE THEY SEE THINGS FOR LONGER THAN 0.1 SECONDS. Moving their eyes Saying an answer out loud (heard by both hemispheres).

Sperry (along with two others) won the 1981 Nobel Prize in Medicine for his work with split-brain research

By the end of this session, you will be able to; Describe the function of the corpus callosum. Identify the functions of the left and right hemisphere. Describe the procedure and results of this study. Be able to identify the actions of a ‘split brain’ patient when given different visual cues.

Summary quiz 1)What did all of the 11 patients suffer from before surgery? 2)Which part of the brain was removed for split brain patients? 3)Which hemisphere is language located in? 4)How long were the symbols/words flashed to visual fields? 5)What was the Dependent Variable?

Summary quiz 6) Which visual field does an object need to be presented to in a split brain patient in order that they can name that object? 7) What happens if an object is presented to the left visual field? 8) Which hemisphere cannot speak or write? 9) What does cross-wired mean? 10) How do the two hemispheres work in split brain patients compared to ‘normal’ brains?

Key Terms Hemisphere (right and left) Corpus callosum Visual field (right and left). Epilepsy Lateralisation of function Quasi-experiment Case study Split brain surgery Cross-wiring Tactile task Visual task

Finish with wordle (Choose your own word to define and link to the study)