PSYCH 109 - Human Neuroscience

Henry Molaison

Henry Molaison - surgery for intractable epilepsy in 1953. Removed much of temporal lobe including hippocampus. Conclusion: These areas are essential for memory. Sadly HM died on December 2, 2008.

Antidepressants

- Prozac - Serotonin agonist - Blocks reuptake - Relieves depression

Dendrites

- Receive nerve impulses from other neurons

Neuropsychology

- 1848 Phineas Gage. - Paul Broca - Henry Molaison

Heroin

- Affects endorphins - which are our pain relieving feel-good hormones - provides euphoria feeling. - Agonist - Mimics at postsynaptic receptor - Analgesia, sedation, euphoria

Left hemisphere function in the split brain

- Can't name objects or words presented in LEFT visual field. - Can't name objects held in LEFT hand. - BUT can understand words in the left visual field (demonstrated by pointing) - Suggests that the right brain can understand, but cannot speak. - Sometimes "cheat". - Right-hemisphere can "tell" the left hemisphere what it sees by looking at an example in the room, so the left hemisphere can then name it. - Coding with the hands, or the tongue! - This is why testing with images in the visual field is very quick.

Neurons

- Communicating elements of the brain. - Perform computations inside the brain that we call "thought". - There are lots of them!

Damage to primary projection areas

- Damage to primary visual cortex causes scotoma - "hole" in the visual field, like a blind spot - Scotoma - missing piece of their vision. - Removal of primary visual cortex on one side > hemianopia on the opposite side - where the right side is damage, and left visual loss (and vice versa).

Damage to prefrontal cortex

- Deficiency in response inhibition. - Inability to plan. - Appear uninvolved, depressed & apathetic. - Some may appear "psychopathic", acting flagrantly and crudely, being sexually promiscuous and may engage in criminal conduct. - perhaps had prefrontal cortex damage, or wired slightly different to normal neural structure. - May find it difficult to changes to a particular task. - Frontal lobes not fully understood.

What can the split-brain tell us?

- Does splitting the brain split the mind? - Split-brain patients seem quite normal. - Everyday evidence of a split mind is rare, but sometimes occurs - "alien hand" - right hand takes on a life of its own. - form of disconnection syndrome. - Left hand would frequently perform oppositely to what she, the patient, desired to do with the right hand. - For example, she would be putting on her clothes with the right hand and pulling them off with the left hand. - Or she opened a door or drawer with the right hand and simultaneously pushed it with the left hand. - Psychological effects of the split brain are best shown by experiment, rather than being evident in everyday life. - Ball isolated in right hemisphere. Speech in the left hemisphere, cannot name ball, but can easily name banana.

Callosal agenesis

- In some people, the corpus callosum does not develop. These people are "naturally" split-brained. - Sometimes accompanied by Probst's bundles, which are remnants of a corpus callosum that failed to cross the midline. - Have other connecting pathways. - Callosal agenesis is often accompanied by other neurological problems, although many of these people seem otherwise normal. - Less evidence of disconnection in callosal agenesis. - Objects and words usually easily named in either visual field. - Interhemispheric transmission time around 20-30 ms, compared with 4-6 ms in normal brain. - So there is some form of compensation, evidence of neural plasticity, probably occurring very early. - brain can cope with these tasks, as it develops other communicating pathways to get information across to other hemisphere. - Also some evidence for plasticity in surgical cases if surgery is early (before puberty). - brain can rewire itself, young enough to do that but not so in older patients.

When a pulse is applied

- In-going channels open, Na+ ions pour into the cell, reversing the voltage difference. - making the inside more positive. - Na+ channels then close, (Potassium) K+ then leaves the cell to restore the original voltage difference. The positive ions are pumped out, retuning the cell to is resting state.

Trigeminal Neuralgia

- Incredibly bad facial pain - aka Suicide Disease - Difficult disorder to treat - May be due to a virus - Takes time for it to go away -

Research looking at normal readers and those with phonological dyslexia:

- Individuals with phonological dyslexia was reading with the right side of their brain, whereas the comprehension is more prominent in the left hemisphere.

Corpus Callosum

- Largest cerebral commissure, over 200 million axons - In constant communication with each other. - In the 1960's ALL forebrain commissures were sectioned - commissurotomy. - all communication between left and right hemisphere were destroyed. - From the 1970's onwards only the corpus callosum was sectioned - callosotomy. - sectioned/cut the front (anterior) of the corpus callosum first and then checked to see if it fixe the epilepsy. If it didn't it will go to the posterior corpus callosum. - Done in two stages - usually anterior, & if this doesn't work, followed by posterior section.

The Split Brain Surgery

- Method of treating and providing relief of intractable, multifocal epilepsy. - abnormal electrical activity would spread very rapidly through the corpus callosum. - Treatment - to prevent the connection. - Separates left & right hemispheres and prevents seizures from spreading through the brain.

Bells Palsy

- People who have one side of their face that droop - no control of facial muscles e.g. may not be able to close/open eye, or smile. - Exists on a continuum on how quickly it gets better. - Do not know what causes it - Do know that some of the cranial nerves are damages. - Do not know how to cure this.

How does it work?

- Resting potential depends on positive sodium ions (Na+) on the outside of the cell membrane. - Ion channels let charged ions in and out of the cell. - In resting state, Na+ ions are kept on the outside by a sodium pump, but in-going ion channels remain closed.

Photic Sneezing

- Sneezing in response to bright light - Genetic

Drugs that stimulate neurotransmitter release

- Stimulate terminal buttons to release neurotransmitters continuously even when the axon is not firing. E.g: Venom of Black Widow Spider: - Acetylcholine agonist - releases lots of acetylcholine. - Exhausts victims supply of acetylcholine - For small prey leads to paralysis and death. - Acetylcholine will paralyse it's muscles.

Axons

- Transmit nerve impulses

Benzodiazepines

- Valium - Tranquilizers essentially. - GABA agonist - exerts sedation. - Reduces anxiety, facilitates sleep

Limbic system (Subcortical Structures of Forebrain)

- located deep in the temporal lobe Amygdala: - Expression of emotion - Responsible for fear - Damaged amygdala = no fear response = not able to survive. Capgrass syndrome: - can recognise faces, but have absolutely no emotional connection to these faces. - they believe that their loved ones are their imposters. - when we looked at loved ones, we have an emotional response. - Loose connection with area between temporal lobe that is associated with recognising faces, and also in the _____ that is associated with emotional responses. Hippocampus: Memory - highly active in the parietal lobe - highly active when we have to find our way in a route. - damage = memory deficits - affects navigation memory as well.

Drugs and the Synapse

1. Stimulate or inhibit neurotransmitter release. 2. Stimulate or block postsynaptic receptor molecules. 3. Inhibit reuptake.

1848 Phineas Gage.

1848, Phineas Gage (construction foreman) had an iron rod rammed through left cheek & skull. Walk & talk, but became unruly, unsociable, bad-mannered, unable to plan. Conclusion: Frontal lobe is important for planning, processing of emotion, rational decision-making. Would this tell us how everyone with frontal lobe damage behaves?

Invasive techniques

1850 brain studied directly by opening skull while subject was alive. Activate/inactivate a region & watch behaviour change. Stimulated with electricity, chemicals, heat or cold. Could also be lesioned (destroyed). If connecting pathways were known tissue could be isolated by cutting (transecting) pathways. Nowadays (thankfully) with arrival of ethics committees - unethical.

Prefrontal lobotomy

1940's - 1950's surgery disconnected prefrontal areas. Helped some - used indiscriminately. Patients - docile but cognitively disabled. No longer widely used after the 1950's due to drugs like Thorazine. Moniz -

The Developing Nervous System

3rd week of embryonic life. Small thickening on top of embryo running from head to (nearly) tail. After a few days left & right edges of the neural plate zip together and fuse lengthwise to form the neural tube. - which forms part of the spinal cord. Brain development happens in day 18 and neural plate fuses into neural tube by day 22. At 1 month the head end of the neural tube develops three thickenings - develop into: -Hindbrain nearest the tail -Forebrain nearest the head -Midbrain between the two Enclosed by cranial bones. Lower edge of hindbrain marks beginning of spinal cord. Brain & spinal cord - Central Nervous System (CNS)

Cell Bodies/Soma:

5-100 microns in diameter - Receives information - Dendrites short - few hundred microns.

Sulgus/Sulci

A sulcus (pl. sulci) is the groove between ridges, also known as a fissure.

Glial Cells

About 90 percent of cells in the brain. Lot of functions within the nervous system. Act as guidewires for growing neurons. Role in repair of damaged tissue. Later in development provide supportive scaffolding for mature neurons, assist in repair process when tissue is damaged.

Prosopagnosia

Agnosia: "not know" Temporal/occipital lobes. Difficulty recognising faces. - Some can't recognise familiar faces. - Some can't recognise a face as a face. Oliver Sacks "The Man who Mistook his Wife for a Hat." However, can form different associations to recognise someone - such as perfume, moment they speak - but cannot recognise by face alone.

How the Nervous System Is Studied

An enormous amount of neurons (individual cells - information processors of nervous system). Each connects to many others. Some techniques allow observation of individual neurons, others a picture of the entire living brain without seriously disturbing its owner.

Drug Effects

Antagonists: - Drugs that block or inhibit postsynaptic effects. Agonists: - Drugs that facilitate postsynaptic effects.

Dyslexia

Any reading disability not associated with obvious problems such as bad eyesight. Occurs more commonly in the left handed. Inability to name letters, read words or sentences, or recognize words directly although they can be sounded out. Acquired: - reading impairment due to left brain damage (including angular gyrus) in those with previously normal language. Deep, phonological, surface - Severe inability to read. - Developmental: - difficulty in learning to read despite adequate intelligence and appropriate educational opportunity. - difficulty distinguishing between words. - might confuse letter P with letter B - 4 times more prevalent in boys than girls. -

Event-related potentials

Average signals across many trials to deal with noise. Stimulus repeated - each EEG response averaged to produce a clearer signal - ERP. Some measure sensory responses to stimuli - N100 - appearing 100 ms after the onset of a stimulus. Some associated with more cognitive functions - P300 & N400.

Occipital lobe

Back of the brain Receives input from the eyes (at the front of the head!) via the thalamus

The Midbrain

Basic role in basic auditory & basic visual stimuli - eye movement. Control animal movements used in sexual behaviour (how they look, movement when they are about to mate) & fighting, decrease sensitivity to pain. e.g. floppy eared animals - hear novel sound - ears would perk up towards sound - this is the midbrain controlling this function.

Dugs that inhibit neurotransmitter release

Botulinum toxin: - Present in improperly canned food - Acetylcholine antagonist - prevents the release of acetylcholine. - Small amount of this toxin - less than one millionth of a gram - victim paralyzed and suffocates to death.

The Left Hemisphere

Broca's area: speech production, syntax Wernicke's area: speech comprehension Arcuate fasciculus: connects the two Angular gyrus: reading - implicated in dyslexia.

Wernicke's aphasia (sensory, receptive, fluent)

Carl Wernicke in 1874. Lack of comprehension. Can't understand what is being said to them. No awareness that anything is wrong with them in terms of conversations. Speaking is fluent & grammatical, but meaningless - jargon aphasia. "T'was brillig and the slithy toves/Did gyre and gimble in the wabe ..." "Well this is ... mother is away here working her work out of here to get her better, but when she's looking, the two boys looking in other part. One there small tile into her time here. She's working another time because she's getting, too" Cookie theft Picture Description from: Carroll, D. (1999) Psychology of Language, 3rd edn, Brooks/Cole Publishing Company.

Branches of the Nervous System

Central nervous system : Brain & spinal cord Peripheral nervous system: 1. Somatic nervous system - Afferent, efferent & cranial nerves - Afferent: take information from sense organs to your brain e.g. eyes, ears. - Efferent: take information from brain to your sense organs e.g. e.g. Afferent = heat from sense organs sending signals to brain. Efferent = brain sends signals to remove hand. 2. Autonomic nervous system Regulation of viscera — heart, lungs, blood vessels, digestion, sex organs. Afferent nerves: Transmit information FROM sense organs TO brain & spinal cord. Efferent nerves: Transmit information from CNS to effectors (muscles/glands that are the organs of action). Cranial Nerves: - 12 pairs - enter/exit from hindbrain (pons/medulla). - Poke through holes in skull - afferent/efferent functions. - Control movements of & carry sensations from head & neck. - Regulate glandular secretions in head. Control visceral functions. - Can create unpleasant side effects as a side effect from illnesses.

TMS Transcranial magnetic stimulation.

Create temporary brain dysfunction, perform experiments that wouldn't be possible otherwise. - Portable, safe, inexpensive and easy to work. Series of strong magnetic pulses (but safe) on scalp, causes temporary disruption in region directly below the area. May have seizures that are generated. Research to see if it is effective in treating depression. Are brain areas used for vision also needed for visual imagery? Not physically

Kluver Bucy Syndrome

Damage to what pathway - don't know what things are, and portray sexual behaviour that is institutionalised.

Medulla (The Hindbrain)

Deals with life support functions. Regulation of heart rate, blood pressure, rate of respiration. Also involved reflexes such as vomiting, defecations, reflexes and swallowing. Simpler animals - looks after basic movements such as crawling or swimming motions.

EEG Electroencephalography

Detects electrical currents generated by neurons on brain surface by affixing metal electrodes to scalp. Used to look at how neurons are working on the outer surface of the brain. Not useful to look for activity any deeper than that. Poor spatial resolution, excellent temporal resolution (picks up fast changes) Squiggly lines - tell you about the person's consciousness at the time of having an EEG. - EEG waves and frequencies. - Output is recorded by a electrocephalogram Resolution improved with high-density arrays.

fMRI Functional Magnetic Resonance Imaging

Detects fast changing aspects of brain physiology (blood flow & oxygen use) without any radioactivity. Blood contains iron, changes in magnetic fields can be detected. More active parts of the brain, would need more oxygen thus would need more blood flowing to these areas. Three dimensional image of brain at work, shows which parts are active. Superimposes activity patterns onto the MRI image. Incredibly expensive to use. fMRI recorded while subjects name animals or tools: - Left hemisphere is more active when asked to name a tool. - Right hemisphere is more active when asked to look at a picture of a screwdriver.

Clinical Observation

Direct clinical observation of patients with brain damage or disease. Link physical brain abnormality with observable changes in behaviour.

Primary Motor Area

Discovered in 1860's. Mild electric currents applied to parts of the cortex in animals. Very specific effects. Evidence of contralateral control - operates in all nervous systems. - left hemisphere, controls movement of right side of body. - right hemisphere, controls movement of left side of body. Canadian Neurosurgeon Wilder Penfield - worked with epileptics needing surgery to remove diseased cells. 400 fully conscious people helped confirm that the primary motor area lies in the frontal lobe and stimulation there led to movement of specific parts of the body.

Spina Bifida

Do not have an intake of folic acid in diet. Central nervous system develops outside the child.

Drugs that stimulate postsynaptic receptor molecules

Dugs can duplicate the effects of some neurotransmitters by directly stimulating particular kinds of receptor molecules. Nicotine stimulates acetylcholine receptors - mimics acetylcholine - similar in shape and structure. Stimulate and bind to the acetylcholine receptors. Low dose: - Pleasurable & addictive - Excitatory effect High dose: - Convulsions & death

The Forebrain

Everything above the midbrain. Mammals (primates) have the largest forebrains. In humans - it's so large that it surrounds & hides from view all the midbrain and half the hindbrain. Most obvious part is the part that is wrinkled - the cortex. The cortex is the outer shell of the brain and is most important for psychological functions.

Lesioning

Experimental brain lesions, usually an injury to brain tissue, in animals. Method use primarily on animal experimentations. Use stereotaxic apparatus to insert a fine wire into a particular location in the brain. - for people who suffer from degenerative diseases, destroying area in brain that deals with movement, to prevent or delay movement problems.

Apraxia

Frontal lobe. - Serious disturbances in initiation or organisation of voluntary action. - Unable to perform well known actions - Other complex, motor movement and actions becomes very disorganised and fragmented.

Unmyelinated Acons

Grey Matter

Preliminary facts about YOUR brain

Huge. About 10 to 100 billion neurons — (units carrying electric signals underlying thought). Single neurons can connect with many other neurons. Brain has enormous computing power! Men's brains are generally bigger than women's. Human brain is 3 times larger, relative to body size, than the chimp (our closest relative). Intricate cerebal cortex - because smarter. Engage in more complex processes. Large amount of area dedicated to sight as it is the main sense we typically use. Consists of two hemispheres - more or less mirror images of each other. Anatomically similar, hemispheres function differently. Left hemisphere dominant for language. Right for spatial awareness, finding your way around space. Brain divided into three major parts, hindbrain, midbrain, forebrain (cortex).

Parietal lobe:

Important for spatial perception. Postcentral gyrus: Receiving area for skin senses (touch, cold, warmth, movement)

Cerebellum (The Hindbrain)

Knows what each part of the body is doing. Receives information from frontal lobes, knows what movements this lobe intends to make the body to accomplish, before you've even moved. Monitors information about posture/balance, produces eye movements that compensate for changes head position. MAY play a role in learning of new movements & movement skills. Very well developed in humans & primates. (1) Controls overall bodily balance = Damage ( direct head injury, disease or alcohol) results in wide stance & staggering gait. (2) Sequencing & timing of precise skilled movements: Damage - tremors during movement & inability to perform rapidly alternating movements. Influences thinking - damage impairs performance of tasks requiring exact sequencing.

Hemispheric specialization

Left-hemispheric dominance for what? Right brain specialities? ... leading to the present-day RIGHT-BRAIN CULT - left and right brain are equally active in specialised task - they are in constant communication with each other.

N400

Linked with language processing. Elicited in sentences where the last word is surprising/inappropriate although linguistically legal: A man who has lost 90% of his brain is called a ______. (zombie) A man who has lost 90% of his brain is called a ______. (widower) N400 would appear in the second sentence. It makes sense however you do not expect that particular word in the end of that sentence. The more difficult the task, the greater the amplitude of the N400.

The homunculus

Mapping body surface onto the motor cortex. It is mapped UPSIDE DOWN Equal sized areas of body DO NOT receive equal amounts of cortical space. Parts that move with greater precision receive more cortical space than those over which we have less control. Top half of primary motor cortex represents the bottom of the body. The top of the body is mapped on the lower half of the primary motor cortex. Equal parts of the body do not receive equal space on the motor cortex. Fine dextrous motor movement: lips, tongue, fingers - get a bigger area of the motor cortex.

Types of Neurons

Motorneurons: - Begin in CNS, exit through spinal cord, end on muscle fibre. Sensory neurons: - Begin at sense organ (retina, skin, tongue) convey information to brain, via spinal cord. Interneurons: - Interposed between other neurons, do much of the computation in the brain. - lie in-between sensory neuron and motoneurons - do much of the computation for thinking.

How do we study how the brain creates mind?

Neuropsychology — the study of how brain injury affects mental processes. Neuroimaging — pictures of the brain's anatomy or function, in relation to mental processes. Technique that allows us to look at brain anatomy. Cognitive neuroscience —modern term that covers both of the above.

Lock and Key Model

Neurotransmitter molecules will only affect the postsynaptic membrane if the molecules shape fits into certain synaptic receptors.

Synaptic reuptake

Neurotransmitters don't sit in the synapse: Repackaged into pre-synaptic membrane. (1) Inactivated by "cleanup" enzymes. (2) Reused in synpatic reuptake.

Roger W. Sperry

Nobel Prize, 1981, "for his discoveries concerning the functional specialization of the cerebral hemispheres" MRI Scan of a split brain - arrows show intact anterior and posterior commissures following callosotomy.

Sign language aphasia

Occurs with sign language, & involves the same areas. Sign language has all the essential properties of spoken language. Professor Corballis's theory - spoken language evolved from sign language! Damage to broca's area - lose grammar in signing Damage to wernickes area - lose meaning in signing.

Why is neglect asymmetrical?

Right side of the brain (parietal lobe) controls attention to both sides of space. Left side controls attention to right side of space only. Therefore damage to the right side causes neglect of the left side. Maybe left side is restricted because of invasive presence of language?

Basal ganglia:

One in the left hemisphere, and one in the right hemisphere (beside the thalamus). Regulation and smoothing of movement. Implicated in a few diseases i.e. parkinsons: degeneration of cells in basal ganglia, causes are unknown, progressive disease that leads to problems of movement of their body. e.g. tremors in the limbs - shaking (Gets worse and more intense as disease progresses) Gait is quite slow and laboured. Trouble with facial muscles - appears quite expressionless and emotionless. Huntingtons disease: - genetic disease - people don't usually find out they have until their 40s-50s - inherited to future generation - uncontrollable jerky limb movements where people lose control. - tremendous difficulty in eating, can lead to choking hazard. Foreign Accent Syndrome: - suffered from a stroke, and speak in different accent. Tourettes Syndrome: - people will have issues with facial ticks. - facial muscle and body will jerk that is out of their own control. - cheek might move uncontrollably. - movement becomes more uncontrollable, when the person is stressed. - rare symptom: vocalisation - people just make a noise, or rare occasion and swear uncontrollable - engage in great profanity without control. Tardive Dyskinesia: - movement problem - Cerebral Palsy:

Drugs that block postsynaptic receptor molecules

Other drugs block receptors, making them inaccesible to the neurotransmitter, & inhibit synaptic transmission Curare - used on darts of blowguns - poison used to hunt animals. Binds to synaptic receptors - and block the ones that are usually taken by acetylcholine. Blocks acetylcholine receptors located on muscle fibres. Victim can't breath & suffocates to death

Hemiplegia

Paralysis of one side of the body. Due to damage to contralateral motor cortex. Paralysis is worse at the extremities (finger movements may be lost, but some movement of the arm maintained). - Depends on the extent of the damage and the areas of the damages. e.g. damage left side of motor cortex - resulting in right side paralysis.

Locked in syndrome

Patients are awake, aware and conscious but they cannot communicate in any form. Traumatic injury, diseases to circulatory and nervous system, overdoses, and myelin which strips neurons of their protective covers which can cause this. Awake & aware but cannot move or speak due to paralysis of all voluntary muscles in the body. Journalist Jean-Dominique Bauby had a stroke in 1995, & when he awoke 20 days later he found that his body was almost completely paralyzed: he could control only his left eyelid. He used this method of communication to write "The Diving Bell and the Butterfly".

Broca's aphasia (expressive, motor, production, nonfluent)

Paul Broca in 1861. Can move tongue, vocalize, swear! Agrammatism - understanding generally alright, but complex syntax not well understood. Language Equivalent ~ 2 year old child. 'Ah ... Monday .... ah Dad and Paul ... and Dad ... hospital. Two ... ah doctors ..., and ah ... thirty minutes ... and yes ... ah ... hospital. And, er Wednesday ... nine o'clock. And er Thursday, ten o'clock ... doctors. Two doctors ... and ah ... .teeth. Yeah, ... fine. Goodglass, 1976, p 278. Picture of a boy being hit in the head by a ball: "The boy is catch ... the boy is hitch .... the boy is hit the ball" Picture of a girl giving flowers to her teacher: "Girl ... wants to ... flowers ... flowers and wants to ... the woman ... wants to ... the girl wants to ... the flowers and the woman"

Paul Broca

Paul Broca studied patients with left frontal lobe damage. Patient called "Tan" - only articulate sound he could make. Conclusion: Broca's area in left hemisphere responsible for articulate speech.

Neglect syndrome

People with right-sided parietal damage tend to neglect the left side of space (seldom vice versa) Refuse to pay attention to the left hand side of their space of the midline. Sustain left-side parietal damage - may lead to disabilities in the right side. Can be visual, auditory, or tactual Problem of attention - sometimes called hemi-inattention - emotional component - when people genuinely believe that nothing is wrong with them, and that the problem lies with other people. An emotional component - denial of any deficit (anosognosia)

Disorders of planning and social cognition

Phineas Gage: "He is fitful, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting but little defense for his fellows, impatient of restraint or advice when it conflicts with his desires, at times pertinaciously obstinate, yet capricious and vacillating, devising many plans of future operation, which are no sooner arranged than they are abandoned in turn for others appearing more feasible. Previous to his injury...he possessed a well balanced mind...was energetic and persistent in executing all his plans of operation. In this regard his mind was radically changed, so decidedly that his friends and acquaintances said he was "no longer Gage" (Valenstein, 1986, p90)

Left Neglect (right brain damage)

Picture drawn, had details from the left omitted. There is some evidence, that people a re processing the left hand side, but refuse to acknowledge it. - Implicit information processed. Tested - by presenting two items that are predominantly the same, with the left one slightly different. - e.g. left house was on fire, even thought its the same house as on the right. - People asked which house they would want to live in - choose the right. - However, their reasoning does not acknowledge the fire - they just think the right house looks nicer.

Pons (The Hindbrain)

Pons - Human arousal - human consciousness, being awake, alert and orienting to things happening around you. - Relays sensory information between cerebellum & cerebrum & other parts of the brain. - Regulates respiration. - Involved in sleep and dreaming. - When damaged in cats, cats act out their dreams, muscles are no long shut down, walking around when they are in fact asleep.

Handedness and the brain

Preceding slides apply mainly to right handers. About 90% of the population are right handed. Nearly all right-handers (97-99%) have language in left brain. About 70% of left handers also have language in the left brain . Remaining 30% have language in the right brain, or bilaterally. More on brain asymmetry shortly! Handed when we are bomb. See this in the womb - babies would suck predominantly with the right thumb or left thumb - children should not be forced to write with their non-dominant hand. - may not help with cognitive tasks further down the track.

Gyrus/Gyri

Precentral gyrus looks after motor. Post central gyrus looks after senses.

Primary & Association Areas

Primary areas - basic input (sensory) & output (motor) Association areas - elaboration, or "higher functions"

Association Areas

Primary areas - less ¼ of cortex. Association areas don't show fixed sensory mapping, implicated in higher mental functions. Cannot point to a particular brain location and say its the organizing centre for "planning" - higher tasks depend on control exerted from many locations.

The Cortex

Primates/complex mammals it accounts for more than ½ the brains volume (80% in humans). Part of the brain that makes us human? Humans gain flexibility of behaviour by having a large cortex. Cortex is 2-3mm thick - made possible by convolutions - if flat would occupy about 2 feet. Tasks performed by nonmammals in subcortical regions (limbic system/midbrain) performed by cortex in mammals. As cortex enlarged in mammalian brain evolution subcortical structures (midbrain) act more as relay stations/ middle managers.

Temporal lobe:

Receiving area for auditory information. Involved in memory. Contains primary auditory cortex - which interprets what you hear. Also important in regards to smell. Damage : can cause olfactory hallucinations. e.g. rotting garbage and excretion

Bling Sight

Report not being able to see an object, but when asked to grasp it, will do so 99 percent of the time, but report that they have no idea where it is & are just guessing randomly. Ancient visual system in midbrain that guides reaching intact, but not connected with higher area of the brain that guides conscious awareness as to object location. Patient TN - blinded by strokes in both hemispheres. Essentially "blind" - no activity in any areas of the brain which control vision. Reacts to facial expressions - scanning shows he can recognize facial emotions (joy/anger/fear)

Frontal lobe:

Responsible for motor output, motor planning. Precentral gyrus Maps onto movements of different parts of the body.

Language Disorders - Aphasia

Result from left-hemisphere damage. - Middle-cerebral artery (MCA) runs close to language areas

Right Neglect (left brain damage)

Right neglect does occur, but is usually transient.

The asymmetrical brain

Right side dominant for: - Spatial attention - neglect. - Melody - amusia. - Facial recognition - prosopagnosia. - Recognition of natural objects - agnosia. Left side dominant for: - Language - aphasia. - Recognition of manufactured objects - agnosia. - Voluntary action - apraxia. - Also for handedness. fMRI recorded naming tools and animals. Tools are represented in the left, animals in the right. Evolutionary - right hand specialisation for use of tools. Therefore perhaps biologically predisposed to wire up Left hemisphere for generativity; language, and manufacture of tools.

MRI Magnetic Resonance Imaging

Safer than CT scanning- no x rays. Magnetic field over head, reverberations produced by hydrogen molecules picked up by scanner. Computer examines signals for subtle differences that identify the tissue that generated them (blood, nerve fibres, or membranes). Creates a 3D anatomical picture of the brain. Very detailed picture: shows tumours, tissue degeneration, blood clots & leaks that may signal strokes. Ventricles - middle bits in the brain. - Filled with spinofluid that nourishes the brain. *

Axon terminals

Secrete neuro transmitters in synapse. Neurons can communicate with each other.

Drugs that inhibit reuptake

Some drugs inhibit the process of reuptake so that molecules of the neurotransmitter continue to stimulate the postsynaptic receptors for a long time. Inhibition of reuptake increases the effect of the neuro transmitter Amphetamins/Cocaine: - Dopamin, norepinephrine, epinephrine agonists. - lot of dopamin left in the synaptic gap and is constantly stimulates the receptors for much longer then they will normally be stimulated. - Affects autonomic arousal, resulting in restlessness, insomnia, loss of appetite, euphoria.

Primary Sensory Areas

Stimulation at particular point - report tingling somewhere in the opposite side of body. Less frequently experiences of cold, warmth or movement. Each part of the body surface sends its sensory information to a particular part of the somatosensory cortex. Sensation is also contralateral Parts of the body that are most sensitive to touch receive more cortical space. e.g. hands and mouth.

Does split-brain surgery work?

Successful in controlling epilepsy - less severe and less damage. Not preferred method of choice - as more successful drugs to treat epilepsy. Dying out with better control through drugs & better understanding of the psychological effects.

Subcortical Structures of Forebrain

Thalamus: Receiving & relay station for sensory input. Receives sensory information from the sense organs (eyes, ears), performs simple brief analyses and passes results on to primary sensory cortex for it to be interpreted. Hypothalamus: Below the thalamus, no relationship with the thalamus. Controls homeostasis & species typical behaviours. Feeding, drinking, body temperature, sex. Controls much of the activity of Autonomic Nervous System. Small, size of a grape (1 cubic centimetre). Controls pituitary glands - control of kidneys, adrenal cortex, and ovaries or testes. - fighting, fleeing, fornication

Neuroimaging

Views of brains anatomy (structure) No invasion of brain tissue, owner of brain is fully awake and conscious. Computerised tomography (CT)** Magnetic resonance imaging (MRI) Positron emission tomography (PET)** Magnetoencephalography (MEG)** Electroencephalography (EEG) Functional magnetic resonance imaging (fMRI) Transcranial magnetic stimulation (TMS)

Agnosia

Visual Agnosia - cannot identify familiar objects. Damage to occipital cortex, parts of temporal & parietal lobes. Can identify separate details of a picture but cannot identify the picture as a whole. Copying drawings. - Individual parts OK, but cannot integrate into coherent whole. Can't put picture together in a coherent format.

How the brain knows where things are:

Visual stimuli (after following an intricate pathway) finally ends up at the occipital lobe, & then is directed to the parietal lobe: "where" system, dorsal stream, location. So if you have damage to the "where" system - you can't locate objects in space, and shape your hand to pick things up, but you know WHAT it is

How the brain knows WHAT things are:

Visual stimuli (after following an intricate pathway) finally ends up at the occipital lobe, & then is directed to the temporal lobe: "what" system, ventral stream, memory. So if you have damage to the "what" system - you can locate objects in space, and shape your hand to pick things up, but you don't know WHAT it is.

Resting Potential

When neuron is not communicating is is in its resting state, the inside of an axon is negative in charge with respect to the surface, by about -70 millivolts. - Not sending an action potential. This is the Resting Potential. If a pulse is applied that exceeds the Excitation Threshold (about -55 millivolts), then an ACTION POTENTIAL occurs. This causes the inside to swing positive relative to the outside. Positive charge moves along axon. Abrupt short-lived reversal of electrical process.

The Synapse

Where one neuron meets another. - neurons don't actually touch - small gaps at end foot of a axon terminal and dendrites of another neuron. Transmission of an action potential along one neuron may cause the next neuron to fire (excitation) or it may inhibit firing (inhibition). Governed by the release of neurotransmitters.

Myelinated Axons

White Matter - wrapped in a protective sheet called myelin - part protein part fat. - insulates the axon - makes action potential faster - about 20m per second - whereas unmyelinated is around 1m per second. Transmission of action potential is faster.

Meninge

White outer surface