The Central Nervous System

The Central Nervous System Year 12 Psychology Unit 3 – The Conscious Self Area of Study 1: Mind, Brain and Body Chapter 4 (pages 177 to 270) PART 1 – Brain Structure, Aphasias

The brain

Think, Think… True or False? • Bigger brains are smarter brains. • You only use about 10% of your brain. • Sleep aids memory formation. • You can grow new brain cells. • Bad diets can cause brain damage. • Thinking bad things can make you sick. • You can be brain dead but remain alive. • The brain is the most complex structure in the known universe. • There is a ‘you’ part of the brain that controls the rest. • The brain is partly made of fat. • No two nerve cells in your brain actually touch. • Your brain uses electricity to think. • Depression is a physiological disease.

Think, Think… Answers • Bigger brains are smarter brains (only between species, sorry big heads don’t mean your smart!) • You only use about 10% of your brain • Sleep aids memory formation • You can grow new brain cells • Bad diets can cause brain damage • Thinking bad things can make you sick • You can be brain dead but remain alive • The brain is the most complex structure in the known universe • There is a ‘you’ part of the brain (that controls the rest) • The brain is partly made of fat • No two nerve cells in your brain actually touch • Your brain uses electricity to think • Depression is a physiological disease

Humans – The Ones With Big Heads!

Characteristics of the brain • 1.5kg of flour – weighs roughly the same as an adult human brain • a ripe avocado – has the same consistency as a human brain • a walnut – represents the convoluted appearance of the cerebral cortex • half a small honey melon – roughly the size of an adult brain

The Brain • Control center for all human behaviour: without understanding our brains and nervous systems we can never fully understand behaviour. • Some scientists argue that all human behaviour can be traced to biological functioning. • Our brains are our most important organ, they make us who we are. • The bigger an organism’s cortex the more intelligent it seems to be – this is NOT true within species. • Whether or not the brain is the sole seat of consciousness it is most certainly part of the puzzle…… • Learning and Memory involve physical changes in your brain!

Your brain will be physically different when you leave this class today!

Famous Brains!

Cerebral Cortex • Is the outer layer of the forebrain; • About 3mm thick, between 2 and 5mm; • Folded to increase cortical surface area; • Contains three-quarters of the entire brain’s neurons; • Divided into 2 hemispheres, each containing 4 lobes; • Responsible for voluntary muscle movements, language, memory, learning, thinking and solving complex problems; • No two brains are the same.

Primary Cortical areas • Somatosensory cortex areas – receive,process and sends information from the senses. • In parietal lobe • Motor cortex area – receives, processes and sends information about voluntary bodily movements. • In frontal lobe • Visual cortex area – receives, processes and sends information about visual stimuli received by both eyes. • In occipital lobe • Auditory cortex area – receives, processes and sends information about auditory stimuli received by both ears. • In temporal lobe

Association areas • Association cortex– describes parts of the cerebral hemisphere other than those that have specialised functions • Association area - combines and integrate sensory(sight, touch, smell, taste, hearing), motor and other information and are involved in complex mental abilities. • These are found in all four lobes

Corpus Callosum • Band of nerve fibres. • Connects the two hemispheres of the brain. • Main function is to enable transfer of information from one hemisphere to the other. • The gap between the hemispheres is called the longitudinal fissure. • Made up of 200 million nerve fibres.

Lobes of the brain

Frontal Lobe • Largest lobe. • Front of the cerebral cortex “forehead”. • Responsible for: • Higher mental functioning: logical thinking, planning and reasoning; • Receiving and coordinating messages from the other lobes; • Broca’s area (in left hemisphere only).

Frontal Lobe (continued…) • Motor control: planning, initiating and performing voluntary movement. • Primary motor cortex: • Controls voluntary bodily movements through control of skeletal muscles; • Cortex in each hemisphere controls movements in the opposite side of the body; • Different areas along the cortex control different parts of the body; • Body parts with more ‘precise’ movement take up more space.

Primary motor cortex • Wiggle each of your fingers one at a time. Remove your shoes and socks. Then try wiggling each of your toes. Try holding a pencil and writing with your toes, now your hands. • The area of your brain devoted to the motor cortex for your fingers is much larger than for your toes, allowing greater flexibility and movement(precise control and dexterity) of the fingers than the toes.

Broca’s Area • Generally in the left hemisphere. • Responsible for production of articulate speech. • Involved with coordinating movements of the muscles required for speech. • If damage is done to this area Broca’s aphasia (also known as non-fluent aphasia) results. • Broca’s aphasia causes speech to be: • slow and deliberate but makes sense; • Leaves out small words like ‘if’ ‘and’ ‘but’. • Eg. “Yes...Monday... Dad and Dick...Wednesday...nine o’clock...ten o’clock...doctors...and...teeth...”

Broca’s Aphasia • Trouble with speech production: • Speech consists of very short and simple sentences, mainly verbs and nouns; • Reading and writing not as effected (can be in some cases though). • Deaf people can sometimes have difficulty signing if Broca’s is damaged. Although this depends on whether they were deaf from birth…..

Example of Broca’s Aphasia ‘stool, is it boy, is it that landing down, girl is laughing, and cookie jar……….ok um…..window….curtains and out the garden and trees low grass and um lady washing the dishes and hot and cold water….plashing running, floor , and the two cups of a, two cups of ah, two cups of ah, coffee or um….empty um……..cupboard and cupboards …..um……washing…..flashing and um earth to roof’

Parietal Lobe • Top of the head. • Registers sensory information: touch, pressure, pain, temperature, bodily movements. • Contains the somatosensory cortex: • More sensitive parts of the body take up more room in this cortex, eg. Hands and face. Homunculus (Latin for ‘Little Human’)

Damage to the parietal lobe • Damage to the parietal lobe may result in difficulty with spatial skills. Spatial Neglect (only for damage in the right hemisphere)

Occipital Lobe • Visual information. • Primary visual cortex: • Involved in receiving and processing visual information; • Where visual information is first transmitted to; • Visual information entering the eye is processed in the occipital lobes of both hemispheres. • See box 4.12 on page 224.

Temporal Lobe • Sides of the brain above ears behind temples. • Auditory perception, language comprehension, some emotional control, and memory (Face recognition). • The task that you would find most difficult if damage occurred in this lobe would be fitting an object into a space. • Wernicke’s Area (in left hemisphere only).

Wernicke’s Area • Stores the receptor codes for language. • Enables comprehension of speech/language. • Enables interpretation of the written word. • Locates words from memory to express a particular meaning. • Creates meaningful and/or grammatically correct speech. • If damage is done to this area Wernicke’s aphasia (also known as fluent aphasia) results: • Trouble with speech comprehension. • Can’t produce meaningful sentences - can string words together but what they say is nonsensical.

Example of Wernicke’s Aphasia ‘Mother is away here working her work to get her better, but when she’s looking the two boys looking in the other part. She’s working another time.’

Wernicke’s Aphasia: example SP: Could you tell me where you are? Frank: …Yes, er, I just don’t feel too good. SP: Are you in hospital at the present time? Frank: …That is really one thing, really I feel bad you know. Mm… I’m not really feeling too good. SP: What’s wrong with you Frank? Frank: Well I don’t know, to be honest you just, er, there will be a few days I feel shy. Saturday was bad, I get bad, Sunday and today. SP: Where do you live? Frank: …I don’t know to be honest, we’ve got a lot of things my dad. SP: Do you live in East Keilor? Frank: …Sorry? Yeh well fair outside things, you can’t do warn. I can talk but I can’t show up myself. I can’t put the voice. It would be one thing if I could talk. But I can’t talk so people can see it. SP: Are you married Frank? Frank: …I was news to due to be.

Jargon Aphasia (a type of wernicke’s) • Poor comprehension but use of neologisms: • Neologisms are invented words which are used as substitutes for actual words. • No awareness of what they are doing. • This is just additional, interesting info – you do not need to remember this!

Jargon aphasia: example Activity: 4.14 • Interviewer: Can you tell me your address Tom. • Tom: Four and pleasant, Plain Sodars. (There is no such district) • Interviewer: How long have you lived there? • Tom: I think that was only Five, no, eight prentices. Small plut be in there. • Interviewer: How old are you? • Tom: 80, 85 no 83 cheldren. (His age is 83 years old) • Interviewer: What month is it? • Tom: Today? Well that would be ten. If I say, it used to be called Naym Prentice. • Interviewer: If I said it was May, what would you say? • Tom: That’s correct, Naym Prentice. • Interviewer: Could you count up to ten. • Tom: A, B, C, D, E, F, M, P, M.

Right Hemisphere and Language? • Patients with left hemisphere damage can sometimes still use emotive words and swear! • Emotion is more a right hemisphere function. • Also, sometimes they can sing what they can’t speak! • Music is more a right hemisphere function. • Interesting Stuff: ‘The Brain That Changes Itself’.

Brain Structure: Task • Create a table that compares and contrasts Broca’s Area with Wernicke’s Area.

The Central Nervous System