The Brain, Scanning and Sperry

Spec check: 4.2.2 Biopsychology Localisation of function in the brain and hemispheric lateralisation: motor, somatosensory, visual, auditory and language centres; Broca’s and Wernicke’s areas, split brain research. Plasticity and functional recovery of the brain after trauma.

Lesson Objectives Recall the key terms already known Identify the 5 areas of the brain Describe all 4 brain scanning techniques used within biopsychology Develop at least 2 strengths of each technique Develop at least 2 weakness of each technique Distinguish between the 2 hemispheres and the tasks they complete Complete an APRC for Sperry’s research Consider a GRAVE for Sperry’s research

SCANNING PET Radioactive material (tracer) is injected (s the brain uses glucose as energy), the areas of the brain which are most active absorb it. Computer produces coloured images of the level of activity occurring throughout the brain.

EEG Based on the assumption that info is processed as electrical activity – action potentials / nerve impulses transmitted along neurons Electrodes attached to the scalp A record of the brain wave patterns produced by millions of neurons, producing characteristic patterns

ERP’s Similar to EEG but key difference is… Isolating specific responses of neurons to specific stimuli or tasks Stimulus presented, picture, … researcher looks for activity related to that stimulus

fMRI Measures brain activity in specific areas by detecting associated changes in blood flow Based on the idea that when we perform a task, the neurons that are most active will use the most energy 3D map of the brain is produced highlighting different areas that are involved in different neural activities

Post Mortem examinations Correlating behaviours before death with brain structures after death Study physical brain of an individual who displayed a certain behaviour which could suggest brain damage Broca is a good example – Tan displayed speech problems – PM highlighted problems with his frontal lobe - - - the specific area known now as Broca’s area

How good is a split brain? SPLIT BRAIN RESEARCH How good is a split brain?

Brains come in two halves… You can see the brain has two hemispheres, the left and right. They appear, from the outside, to be identical.

These halves are normally held together… By the corpus callosum - communication between the hemisphere is predominately via these pathways. By the corpus callosum - communication between the hemisphere is predominately via these pathways. Pathways are severed in some patients with severe epilepsy. NOTE: the OPTIC CHIASM is not severed, and the MOTOR CONNECTIONS from the contra-lateral side of the body are also left intact with this procedure. Thus, the left hand is still controlled by the right hemisphere and the right hand by the left hemisphere. Key term

Sometimes this bridge is cut through… Pathways are severed in some patients with severe epilepsy Why? See http://nawrot.psych.ndsu.nodak.edu/Courses/465Projects05/splitbrain/splitbrain2.htm Specifically, in split brain patients, it is the corpus callosum which is severed. For more info : http://nawrot.psych.ndsu.nodak.edu/Courses/465Projects05/splitbrain/splitbrain2.htm

NOTE: the OPTIC CHIASM is not severed, and the MOTOR CONNECTIONS from the contra-lateral side of the body are also left intact with this procedure. Therefore, the left hand is still controlled by the right hemisphere and the right hand by the left hemisphere.

So what did he actually do?! Sperry won the Nobel Prize in Medicine & Physiology in 1981 "for his discoveries concerning the functional specialization of the cerebral hemispheres" as a result of this work. So what did he actually do?! Sperry won the Nobel Prize in Medicine & Physiology in 1981 "for his discoveries concerning the functional specialization of the cerebral hemispheres" as a result of this work.

severed in a split brain operation). It is more complex with vision because the fields overlap and information is exchanged over the optic chiasm (not severed in a split brain operation). Following a split brain operation, the view of the left visual field is represented only in the right hemisphere and the view of the right visual field is represented only in the left hemisphere. It is more complex with vision because the fields overlap and information is exchanged over the optic chiasm (not severed in a split brain operation). Following a split brain operation, the view of the left visual field is represented only in the right hemisphere and the view of the right visual field is represented only in the left hemisphere.

REMEMBER: left hemisphere, responsible for speech The participant is asked to look at the fixation point in the middle of the screen. The dollar sign, presented to the left visual field, is passed only to the right hemisphere. The question mark, presented to the right visual field is passed only to the left hemisphere. The patient will therefore respond to ‘point with your left hand to what you saw’ by pointing to the ‘dollar sign’ …. …..but when asked ‘say what you saw’, they will respond by saying ‘a question mark’. This is because the left hand, controlled by the right hemisphere, is only aware of the dollar sign. The left hemisphere, responsible for speech, is only aware of the question mark. REMEMBER: left hemisphere, responsible for speech The participant is asked to look at the fixation point in the middle of the screen. The dollar sign, presented to the left visual field, is passed only to the right hemisphere. The question mark, presented to the right visual field is passed only to the left hemisphere. The patient will therefore respond to ‘point with your left hand to what you saw’ by pointing to the ‘dollar sign’ but when asked ‘say what you saw’, they will respond by saying ‘a question mark’. This is because the left hand, controlled by the right hemisphere, is only aware of the dollar sign. The left hemisphere, responsible for speech, is only aware of the question mark. Have a look at http://web.umr.edu/~pfyc212b/ch2b%5B1%5D/sld018.htm

Two different objects are flashed up on either side of the fixation point. When the participant is asked to find the thing they have seen with his left hand (which he cannot see because it is behind the screen) he feels for and locates the pear. The image of the pear, presented to the left visual field, has only entered the right hemisphere and this is guiding the left hand. When, in contrast, the participant is asked to verbally report what he has seen, he says ‘five’. This is because a number five was presented to the right visual field and is available to the speech areas in the left hemisphere. Two different objects are flashed up on either side of the fixation point. When the participant is asked to find the thing he has seen with his left hand (which he cannot see because it is behind the screen) he feels for and locates the pear. The image of the pear, presented to the left visual field, has only entered the right hemisphere and this is guiding the left hand. When, in contrast, the participant is asked to verbally report what he has seen, he says ‘five’. This is because a number five was presented to the right visual field and is thus available to the speech areas in the left hemisphere. See also websites: http://erraticwisdom.com/2006/02/24/split-brain http://faculty.washington.edu/chudler/split.html http://www.its.caltech.edu/~jbogen/text/ref130.htm

An object flashed to one visual field only, pts responds differently depending on the side. If the object is shown to the right visual field it enters the left hemisphere and is reported verbally (eg ‘I see a ball’). The participant cannot however find the object with their left hand because the right hemisphere is unaware of what has been presented. If the object is shown to the left visual field it enters the right hemisphere and the participant can find the object with their left hand (eg the pencil). The participant will claim, verbally, to have seen nothing because the left hemisphere is unaware of what has been presented. When a participant has an object flashed to one visual field only, they respond differently depending on the side. If the object is shown to the right visual field it enters the left hemisphere and is reported verbally (eg ‘I see a ball’). The participant cannot however find the object with their left hand because the right hemisphere is unaware of what has been presented. If the object is shown to the left visual field it enters the right hemisphere and the participant can find the object with their left hand (eg the pencil). The participant will claim, verbally, to have seen nothing because the left hemisphere is unaware of what has been presented. Another illustration can be seen at: http://cwx.prenhall.com/bookbind/pubbooks/morris2/chapter2/medialib/summary/6.html

Since the images reaching the left and right hemispheres from the two visual fields are independent in split brain patients, like Nicola, they can perform two tasks at once without interference. They are, in fact, somewhat quicker than normal participants at such responses! Since the images reaching the left and right hemispheres from the two visual fields are independent in split brain patients they can perform two tasks at once without interference. They are, in fact, somewhat quicker than normal participants at such responses! See http://physics.weber.edu/carroll/Wonder/split_brain.htm

So what’s going on? So what’s going on? Normally, communication is possible between the left and right hemispheres so both sides of the brain have access to information about both visual fields and have access to speech. This is because information is transferred across the corpus callosum. See also http://www.richmond.edu/~pli/teaching/psy333/neuro_60splus.html Normally, communication is possible between the left and right hemispheres so both sides of the brain have access to information about both visual fields and have access to speech. This is because information is transferred across the corpus callosum

So, what does all this tell us? A little about what it’s like to be human – we talk about having a stream of consciousness, but that seems to be composed of two trains of thought that have to be united: the function of the corpus callosum, which integrates our understanding, especially of emotional, spatial, creative and other aspects of our interpretation of the world and combines it with our ability to sequence, to speak and to apply logic. It allows us to express our grasp of a complex physical and social world. A little about what it’s like to be human – we talk about having a stream of consciousness, but that seems to be composed of two trains of thought that have to be united: the function of the corpus callosum, which integrates our understanding, especially of emotional, spatial, creative and other aspects of our interpretation of the world and combines it with our ability to sequence, to speak and to apply logic. It allows us to express our grasp of a complex physical and social world.

How do the hemispheres differ? Left hemisphere Right hemisphere Speech Production of speech, comprehension of the literal meaning of speech Emotional inflections, understanding jokes & humour, sarcasm, emotional content of speech Auditory System Sounds related to speech Non-language environmental sounds (e.g., rain) and music Emotions Expressions of happiness Expressions of anger, fear, disgust; interpreting the emotional expressions of other people Vision Details Spatial processing (eg arranging pieces of a puzzle or drawing a picture) How information is used Details, parts, pieces Overall configuration What information is used High spatial frequency: many and frequent visual changes  Low spatial frequencies: few visual changes  How do the hemispheres differ? How do the left and right hemispheres differ?

A man who had been trying to quit smoking tried to light up a cigarette and once he got it lit his left hand would grab the cigarette and put it out!

A man and his wife were having a discussion that his right brain must not have agreed with. In order to show its dismay with the topic of conversation, the left arm tried to hit the wife! The man had to physically wrestle the left arm in order to stop it.

After her commisurotomy a woman was oversleeping for work, but her right brain heard her alarm and woke up. It realized that the left brain was not aware of the alarm and that she, therefore, wasn’t aware of it either. The left hand (right brain) was so frustrated with the situation and slapped her across the face to wake her up!

Where to now? If you’ve found this interesting, you might enjoy this ‘game’ on the Nobel Prize website! YouTube for more videos! In the seminars this week we will explore Nicolas condition in more depth Also, we need to be able to evaluate this research http://nobelprize.org/educational_games/medicine/split-brain/

4.2.2 Biopsychology • The divisions of the nervous system: central and peripheral (somatic and autonomic). • The structure and function of sensory, relay and motor neurons. The process of synaptic transmission, including reference to neurotransmitters, excitation and inhibition. • The function of the endocrine system: glands and hormones. • The fight or flight response including the role of adrenaline. • Localisation of function in the brain and hemispheric lateralisation: motor, somatosensory, visual, auditory and language centres; Broca’s and Wernicke’s areas, split brain research. Plasticity and functional recovery of the brain after trauma. • Ways of studying the brain: scanning techniques, including functional magnetic resonance imaging (fMRI); electroencephalogram (EEGs) and event-related potentials (ERPs); post-mortem examinations. • Biological rhythms: circadian, infradian and ultradian and the difference between these rhythms. The effect of endogenous pacemakers and exogenous zeitgebers on the sleep/wake cycle.

So, ensure you have notes I would have an APRC and GRAVE of Sperry Use your text books to add to todays info Start reading about plasticity of the brain Add to your glossary's Always exam questions to practice as well 