Neuropsych lectures 830:310
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This 68 page Class Notes was uploaded by Mumana Ahmed on Tuesday August 9, 2016. The Class Notes belongs to 830:310 at Rutgers University taught by Anthony Dick in Fall 2016. Since its upload, it has received 21 views. For similar materials see Neuropsychology in Psychology at Rutgers University.
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Date Created: 08/09/16
09.16.15 Neuropsych Lecture 5 Spinal cord & cranial nerves Bloodbrain barrier Endothelial cells of brain capillaries have tight junctions Astrocyte feet cover endothelial cells Small uncharged molecules can pass Other molecules get across with active transport Absent bloodbrain barrier Circumventricular organs: rd 3 ventricle SFO and OVLT 4 ventricle area postrema Three germ layers: Ectoderm develops into nervous tissue and epidermis Mesoderm middle layer; develops into skeletal system and muscles Entoderm develops into organs (Non)closure Neuropore closing (day 2428) Anencephaly no brain; frontal neuropore does not close Spina bifida Lissencephaly (agyria) Due to defective neuronal migration Genetic, viral, hypoxia during 1 trimester Vertebra (identified by area and number ex. L3) Cervical vertebrae (8) in the neck Thoracic vertebrae (12) chest cavity Lumbar vertebrae (5) lower back Sacral vertebrae (5) Coccygeal vertebrae (1) Spinal cord ends after thoracic Spinal cord Dermatomes body segments innervated by spinal nerves Lumbar puncture Area is made numb by local anesthetic A small needle is passed between the vertebrae of the spine and posterior to the end of the spinal cord No risk of paralysis 09.21.15 Neuropsych Lecture 6 Spinal cord & cranial nerves (2) A motor neuron of the peripheral nervous system Cell body is located in spinal cord But axon runs through spinal nerve Sensory neuron of peripheral nervous system Sensory neuron of the PNS sending afferent information to the spinal cord from the skin Cell body in dorsal root ganglion a cluster of nerve cell bodies (a ganglion) in a posterior root of a spinal nerve Tactile stimulation light touch, painful stimulus, thermal stimulus A nerve is a bundle of axons from many neurons. Therefore, a nerve is a collective targeting of information. Gray matter cell bodies, dendrites, synapses White matter myelinated axon tracts In brain gray matter is located in the middle In spinal cord gray matter is located in the middle with white matter surrounding it Spinal cord injuries Spinal cord damage Most common in men (sports/working accidents) The higher up on spinal cord the damage is, worse the consequences Christopher Reeve: C1C2 (spinal cord damage) Paraplegic loss of control over lower limbs Quadriplegic/tetraplegic loss of control over all limbs Sympathetic branch thoraciclumbar region Parasympathetic branch craniosacral region Decussation crossing (each hemisphere of brain runs opposite side of body) Structure of the vertebrate nervous system Medulla: Located just above the spinal cord and could be regarded as an enlarged extension of the spinal cord Several tracts cross (decussate) here Responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing and sneezing Cranial nerves Cranial nerves are functionally homologous to the spinal nerves Provide both somatic and visceral sensory and motor innervations of the head and neck Traditionally numbered I through XII in rostrocaudal sequence The Cranial Nerves I. Olfactory smell II. Optic vision III. Oculomotor control of eye movements, pupil constriction IV. Trochlear control of eye movements V. Trigeminal skin sensations from most of the face, control of jaw muscles for chewing and swallowing VI. Abducens control of eye movements VII. Facial taste from the anterior twothirds of the tongue, control of facial expressions, crying, salivation, and dilation of the head’s blood vessels VIII. Statoacoustic hearing (auditory), equilibrium (vestibular/balance) IX. Glossopharyngeal taste and other sensations from throat and posterior third of the tongue; control of swallowing, salivation, throat movements during speech X. Vagus sensations from neck and thorax; control of throat, esophagus, and larynx; parasympathetic nerves to stomach, intestines, and other organs XI. Accessory (spinal accessory) control of neck and shoulder movements XII. Hypoglossal control of muscles of the tongue On Old Olympus’ Towering Top A Fin And German Viewed Some Hops Some Say Marry Money But My Brother Says Big Brains Matter More 09.08.15 Neuropsych Lecture 2 History/theoretical issues/terminology Ancient Neurosurgery Trephination/trephining or trepanning Holes made in the skull to relieve pressure on the brain Holes were scratched out by rocks Not uncommon Where does behavior originate? Cardiac hypothesis idea that the heart is the seat of such emotions as love and anger Brain hypothesis Hippocrates Believed the brain was the seat of intelligence and controller of senses, emotions, and movement Galen Believed the mind controlled fluids known as pneuma (animal spirits) Physical functioning was dictated by the balance of four bodily fluids or humors blood, mucus, yellow bile, black bile Better anatomical knowledge Galen knew most about animal brains, had performed dissections Vesalius (anatomist) made detailed diagrams of human brain anatomy Thomas Willis published first book on the brain and nerves But where’s the mind? Descartes Dualism, mind is immaterial, brain is material Problems with causalityhow does the mind cause the body to move? Materialism all that exists is physical, so no mind Monism mind and brain are identical Dual aspect theory two views on same thing Dual property two properties of the same entity Localization of Function: Phrenology Phrenology the idea that brain is the organ of the mind, and that different parts of the brain have different functions Franz Joseph Gall introduced idea that the brain is made up of separate organs, each localized and responsible for a basic psychological trait There is no relationship between bumps on skull and underlying brain tissue Johann Caspar/Gaspar Spurzheim published a book Localization of Function: Broca & Wernicke Broca’s area speaking/expression of language localized to left frontal lobe Wernicke’s area comprehending language localized to posterior of (usually) left parietal lobe Equipotentiality Pierre Flourens (experimentalist) Cut different parts out of the brain and studied resulting changes in behavior Concluded that loss of function in the brain is more due to amount of damage rather than location of damage Brain has plasticity and can adjust to damage Cortex can make up for other lost cortex Equipotentiality the capacity of any intact tissue of the brain to carry out the functions of the damaged area John Hughlings Jackson & Alexander Romanovich Luria Jackson claimed that the nervous system is an evolutionary hierarchy of three levels connected by the process of weighted ordinal representation Cortex is highest evolutionary level of nervous system, controls and inhibits function of lower levels The synthesis of localization of function with equipotentiality Nervous system Central nervous system things encased Brain encased by skull Spinal cord encased by vertebrae Peripheral nervous system neurons that connect CNS to the rest of the body Somatic nervous system controls muscles (voluntary) o Afferent nerves go towards the brain o Efferent nerves go away from the brain Autonomic nervous system automatic control of internal organs (involuntary) o Afferent nerves go towards the structure o Efferent nerves go away from the structure Parasympathetic nervous system calms body, conserves energy Sympathetic nervous system arouses body, uses energy Directions Terminology Dorsal back Ventral stomach Caudal tail Rostral snout/beak Anterior in front Posterior behind Superior above/upper Inferior below/lower Lateral to the side Medial to the middle 09.09.15 Neuropsych Lecture 3 Cells & Development Two general types of cells in the brain neurons and glial cells Sensory neurons send sensory messages towards the brain Motor neurons send messages away from the brain to muscles and glands Interneurons within brain and spinal cord; communicate internally and intervene between sensory and motor information Dendrite bushy, branching extensions of a neuron that receive messages and conduct impulses toward cell body Axon extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles/glands Myelin sheath layer of fatty tissue encasing fibers of many neurons (axons), enables faster transmission speed of neural impulses Synapse junction between axon tip of the sending neuron and dendrite or cell body of receiving neuron Glial cells support, nourish, and protect neurons; clean up cell damage Microglia primary immune cells and brain defense Macroglia Oligodendrocytes cells that coat axons in CNS to form myelin Schwann cells cells that become myelin in peripheral nervous system (PNS) Astrocytes most abundant; regulate external chemical environment of neurons Name of neuron is determined by the number of processes that come off the cell body (unipolar neuron, bipolar neuron, multipolar neuron, multipolar interneuron) Neuron bodies and axons (in the brain) White matter mostly axons Gray matter mostly cell bodies Multiple sclerosis (multiple scars) Demyelinating disorder (myelin is damaged) Mechanism: demyelination Proximal cause: autoimmune (body starts attacking own body) Body attacks oligodendrocytes in myelin Distal cause: possible genetic susceptibility and environmental trigger Symptoms: sensory, motor, cognitive, emotional problems Onset, diagnosis, progression: commonly 2040, more often in women, various forms of progressionattacks, remissions Treatment: attacks, progression, symptoms Incidence: 1 in 2000 in US No cure; life expectancy of 5 years less than average Basic processes in development of nervous system Neurogenesis (formation of neurons) and migration Synaptogenesis formation of synapses/connections between neurons Myelination creation of myelin Synaptic pruning getting rid of unnecessary synapses to increase efficiency 09.23.15 Neuropsych Lecture 7 Anatomy & Brain Damage Structure of the Vertebrate Nervous System Located at caudal portion of brain Forebrain Telencephalon Cerebral cortex o Receives sensory information and controls motor movement from the opposite (contralateral) side of the body Limbic system (mostly subcortical) o Traditionally viewed as involved in the expression of emotions Basal ganglia (subcortical) o Concerned with the control and coordination of movement patterns Diencephalon (subcortical lying below the cerebral cortex) Thalamus consciousness, sleep, alertness Hypothalamus motivated behaviors, sends messages to pituitary gland Midbrain Mesencephalon Tectum roof of the midbrain o Superior colliculus and inferior colliculus swellings on each side of the tectum o Superior colliculus visual processing and control of eye movements o Inferior colliculus auditory processing Tegmentum the intermediate level of the midbrain Substantia nigra has many dopamineproducing neurons; provides dopamine for parts higher up in brain. When dopamine production here stops, it causes Parkinson’s disease Hindbrain Metencephalon Pons o Origin of neuronal activity that serves to increase arousal and readiness of other parts of the brain Cerebellum o Structure with many deep regular folds o 3 functional parts: 1. Flocculonodular lobe vestibulocerebellum helps regulate balance and eye movements 2. Spinocerebellum helps regulate body and limb movements 3. Cerebrocerebellum helps in planning movements and evaluating sensory information for action, and has some purely cognitive functions (important for shifting attention between auditory and visual stimuli) Myelencephalon Medulla helps regulate breathing, heart and blood vessel function (center for respiration and circulation) Reticular formation A diffusely arranged network of neurons that extends from the mesencephalon (midbrain) through the metencephalon (where it is most concentrated) to the myelencephalon (hindbrain) Descending portion is one of the several brain areas that control the motor neurons of the spinal cord Ascending portion projects to much of the cerebral cortex, selectively increasing arousal and attention Limbic System Consists of a number of other interlinked subcortical structures that form a ringlike border (limbus) around the brainstem Olfactory bulb Hypothalamus Hippocampus learning and memory storage, including emotional memory Parahippocampal gyrus Amygdala expression of fear Cingulate gyrus of the cerebral cortex (belts/goes around the corpus callosum) Associated with motivation, emotion, drives and aggression Hypothalamus Small area near the base of the brain Conveys messages to the pituitary gland to trigger the release of hormones Pituitary gland hormone producing gland found at the base of the hypothalamus Associated with behaviors such as eating, drinking, sexual behavior, and other motivated behaviors Basal Ganglia Includes: Caudate nucleus (aka striatum) Putamen (aka striatum) Globus pallidus Associated with planning of motor movement Execution of automatic action sequences Involved in aspects of memory and emotional expression Diseases that affect the BG are notable by virtue of the dramatic change in motor performance Cerebral Cortex Sulci small grooves (sulcus singular) Fissures large grooves Longitudinal fissure the groove that separates the right and left hemispheres Sylvian or lateral fissure the groove that separates the frontal and parietal lobes from the temporal lobes under them Gyri bulges (gyrus singular) Corpus callosum a large tract of myelinated fibers (bundled axons) connecting the two hemispheres Neuropsychological Research Methods Main categories of research methods: 1. Examine the effects of brain damage on behavior 2. Image brain 3. Record brain activity during behavior 4. Examine the effects of stimulating particular parts of the brain Brain Injury Main types: 1. Traumatic brain injuries (TBI) 2. Tumors 3. Cerebrovascular accidents/disorders 4. Infections Less common: 5. Neurotoxins 6. Genetic factors Brain Tumors Tumor “neoplasm” (new tissue) Morbid enlargement or new growth of tissue Cell division and proliferation is uncontrolled 3 classifications (can overlap) “Badness” Malignant progressive (keeps growing) Benign cell growth stopped o Still capable of producing neurobiological problems Tendency to grow into adjacent areas (infiltrative vs. noninfiltrative) Place of origin of tumor Local (originates from the brain can be either infiltrative or noninfiltrative) Metastasized arises elsewhere Characteristics of Brain Tumors Local tumors arise from any local cells residing in affected organ Blood vessels Meningioma tumor in meninges 15%+ of brain tumors (usually benign) Glioma tumor in glial cells 4050% of brain tumors Astrocytomas Glioblastoma multiforme (GBM) aggressive local malignant infiltrative tumor Ependymal cells lining ventrides: ependymomas, oligodendriomas, oligoastrocytomas Acoustic neuroma tumor in myelinating cells surrounding auditory nerve Cancerous neurons are rare Metastasized Tumors Metastasis Circulation and spreading of cancer cells to locations distal to organ/tissue of origin Metastatic tumors in secondary sites are not of the same type as the infiltrated organ/tissue Growth in secondary sites upsets metabolic needs and functions of the resident cells Regarded as primary tumor and secondary (metastatic) tumor *40% of brain tumors are metastatic 09.14.15 Neuropsych Lecture 4 Parts of CNS, Meninges, CSF, Blood supply Seven basic parts of the CNS: 1. Spinal cord Receives sensory messages from periphery Orders to muscles travel through 2. Medulla oblongata Includes nuclei for several autonomic centers 3. Pons 4. Cerebellum “little brain” 5. Midbrain Contains sensory and motor functions Visual and auditory reflexes are coordinated 6. Diencephalon Contains thalamus and hypothalamus 7. Cerebral hemispheres Occipital lobes vision Temporal lobes auditory functions Parietal lobes movement and space Frontal lobes control of movement, judgment, reasoning, thinking Phylogenetics the study of evolutionary relationships b/w different groups of organisms Vertebrate brains Prosencephalon (forebrain) Mesencephalon (midbrain) Rhombencephalon (hindbrain) Spinal cord Mammalian brains Telencephalon (endbrain) Diencephalon (between brain) Mesencephalon Metencephalon (across brain) Myelencephalon (spinal brain) Spinal cord Fully developed human brain Forebrain neocortex, basal ganglia, limbic system, olfactory bulb, lateral ventricles Brainstem Thalamus, hypothalamus, pineal body, third ventricle Tectum, tegmentum, cerebral aqueduct Cerebellum, pons, fourth ventricle Medulla oblongata, fourth ventricle Spinal cord Divisions of the brain Hindbrain Metencephalon cerebellum, pons Myelencephalon medulla Midbrain Mesencephalon Forebrain Telencephalon Brain hemispheres Diencephalon Thalamus, hypothalamus The Meninges A series of three membranes protecting the CNS Dura mater outer layer Dura folds and divides brain into hemispheres and separates cerebrum from cerebellum Arachnoid middle layer Overlies the subarachnoid space Contains blood vessels Pia mater inner layer Overlies every detail of the outer brain Major division Ventricles Subdivision Forebrain Lateral Telencephalon Third Diencephalon Midbrain Cerebral aqueduct Mesencephalon Hindbrain Fourth Metencephalon Myelencephalon Cerebrospinal fluid (CSF) Steps: 1. Produced in the lateral ventricles 2. Circulates around lateral ventricles and third and fourth ventricles 3. Gets into subarachnoid space 4. Circulates around brain Contained within four brain ventricles (CSF buildup results in hydrocephalus) Produced by the choroid plexus of ventricles Floats the brain so it doesn’t crush arteries and veins under the brain Protects brain as a physical buffer Does some waste removal and distribution of chemicals Cerebral blood supply Main supply arteries Vertebral arteries (2 in back) Internal carotid arteries (2 in front) Circle of Willis Vertebral arteries join together to form the basilar artery Posterior cerebral arteries come off of basilar artery Posterior communicating arteries communicate b/w posterior cerebral arteries and middle cerebral arteries (comes off internal carotid arteries) Anterior cerebral arteries come off of internal carotid arteries One small anterior communicating artery connecting the anterior cerebral arteries There can be slight variance in anatomy in some people Major Arterial Supply of Principal Structures (vascularization) Frontal lobe Lateral surface Middle cerebral artery Medial surface Anterior cerebral artery Inferior surface Middle and anterior cerebral arteries Temporal lobe Lateral surface Middle cerebral artery Medial surface Middle and posterior cerebral arteries Inferior surface Posterior cerebral artery Parietal lobe Lateral surface Middle cerebral artery Medial surface Anterior cerebral artery Occipital lobe All surfaces Posterior cerebral artery Cerebellum Receives arterial supply coming off basilar artery 09.30.15 Neuropsych Lecture 9 Infections Caused by exogenous pathogen Viruses (encapsulated nucleic acid ex. DNA or RNA) Bacteria Fungus Inflammation response to presence of microbial agents Meningitis Inflammation of meninges Fungal is most serious Encephalitis inflammation of brain; affects medial temporal lobe (and limbic system in general) Seizures (epileptic) Hallucinations Muscle stiffness Personality changes Impaired judgment Dementia Can be caused by rabies, HPV, polio, and measles Herpes virus Genital and oral (cold sores) blistering Affects the CNS Infection can occur outside CNS Once in nervous system, Remains dormant Upon activation leaves cells and induces immune response Neurotoxins Toxins that work specifically on nerve cells (venoms) Environmental chemical toxicants Examples: Mercury Lead Drugs of abuse Alcohol Stimulants (ex. cocaine, methamphetamine) Glutamate excitotoxin 10.12.15 Neuropsych Lecture Methods of Visualizing the Brain Histology the study of tissue Radiological procedures using xrays General xray images Computerized axial tomography (CT or CAT) Magnetic resonance imaging (MRI) Functional MRI (fMRI) Diffusion tensor imaging (DTI) Positron emission tomography (PET) Electrophysiological procedures Histology Determination of the structure and morphology of tissue Need to stain tissue in order to be able to see cells For brain: only postmortem or biopsy Golgi stains using silver chromate on brain tissue stains some neurons all black Nissl stains dyes only and all cell bodies; allows you to count cells and see organelles Myelin stains stains myelin Tracing procedures Ex. horse radish peroxidase (HRP) Retrograde transport Ramon y Cajal Drew picture of neurons with Golgi stains Introduced microscopic structure of brain Noninvasive procedures Cranial (skull) xrays Discrimination of low and high density regions in the body High density areas (ex. bone) seen as white on xray film Low density seen as dark Disadvantage: poor discrimination between brain tissue and CSF Advantages: picks up tumors, skull fractures and hemorrhage, cheap, easily available Disadvantages: only 2dimensional images, poor structural resolution (i.e. brain regions difficult to discern), cumulative radiation Angiography (graphing blood vessels) Visualization of cerebral vasculature Catheter inserted via an external artery (ex. femoral artery) and guided close to the site of entry of arterial supply of the brain (ex. internal carotid) Contrasting dye is injected Take skull xray or CT Of diagnostic use only Aneurysms Tumors with new vasculature Vascular shifting due to lesions or degeneration of brain tissue CAT (computerized axial tomography) Xray scanner is rotated slowly until a measurement has been taken at each angle and a computer constructs the image Xray delivered as a thin beam This allows for “slices” of the brain to be constructed along each of the planes of axis A computer reconstructs a 3D image Discrimination between brain structures is superior to that of skull xrays Can use contrast medium to enhance image MRI (magnetic resonance imaging) Involves the application of a powerful magnetic field to image the brain Magnetic field aligns axes of the natural spin or rotation of atoms in water molecules (esp. hydrogen atoms) Radiofrequency signal causes all aligned axes to spin like gyros Termination of radiofrequency signal causes nuclear atoms to return to original state, releasing electromagnetic energy in the process Released energy is measured and used to visualize the structure of the brain MRI is applicable to any body organ Functional MRI (fMRI) Uses oxygen consumption in the brain to provide a moving (dynamic) and detailed image of the functioning brain fMRI will also calculate regional blood flow (CBF: cerebral blood flow) Subtraction techniques are used to ensure that a given task or stimulus is responsible for the activity detected in a particular area of the brain The fMRI is a powerful tool since it reveals the level of activity of a particular brain region, as well as the size and appearance of various areas of the brain DTI (diffusion tensor imaging) MRI in which water diffusion at a location is calculated Shows preferred direction of diffusion Allows for visualization of directional fibers Shows white matter tracts PET (positron emission tomography) Records emission of radioactivity from injected radioactive chemicals to produce a highresolution image PET typically uses radioactively labeled glucose Radiolabeled neurotransmitterrelated substances now used Variants of PET are rCBF (regional cerebral blood flow) Shows tumors well because tumors like glucose 10.14.15 Neuropsych Lecture Recording the brain’s electrical activity Three techniques for electrical recording: Single cell recording Electroencephalograph (EEG) recording Event related potential (ERP) recording Neuronal activity Membrane potential voltage difference between the interior and exterior environment of a cell Negatively charged and positively charged elemental ions (e.g. chloride, sodium, potassium, calcium) provide the concentration gradients responsible for voltage difference across the cell membrane Single Cell Recording An electrode is inserted into the brain, adjacent to a neuron, the neurons activity is recorded Most commonly done with animals (nonhuman primates cats, rodents) Many individual neurons can be recorded simultaneously Can record a single action potential or many action potentials Not conducted in humans Electroencephalographic (EEG) recording Discovered by Hans Berger in the 1930s EEG records electrical potentials or “brain waves” in the brain Reflects the collective (and synchronous) activity of neurons in the cortex Electrodes are attached to the skull corresponding to specific areas of the brain Requires a “generator” Neurons that produce the rhythmical signal EEG used for: Sleep studies Epilepsy diagnosis Monitoring the depth of anesthesia Studying normal brain function Event Related Potentials (ERPs) Brief change in a slowwave EEG signal in response to a discrete sensory stimulus is classified as an ERP Often referred to as evoked potentials (e.g. auditory evoked potential) Averaging of auditory evoked potential: Stimulus is presented repeatedly and the recorded responses are averaged P300 phenomenon typically associated with meaning of a stimulus (e.g. stimulus predicts reward or a variation in a stimulus pattern is detected) Transcranial Magnetic Stimulation (TMS) Transcranial magnetic stimulation the application of intense magnetic fields to temporarily inactivate neurons Can be used as therapy for depression Can be used for improving motor function in people with Parkinson’s disease Sleep (machines involved) Electroencephalogram (EEG) Electrooculogram (EOG) for recording eye movement Electromyogram (EMG) Sleep distinctions Waves (EEG) Stages Types of sleep EEG and states of awareness EEG patterns are associated with particular behavioral states Beta rhythm alert awake state Alpha waves calm and resting Theta waves drowsiness Delta waves deep sleep Four distinct NREM stages of sleep N1 drowsy, slowed frequency, increased amplitude of waves N2 asleep slower, higher amplitude delta waves (sleep spindle and K complex) N3 deep sleep appearance of slower waves N4 deep sleep slow wave sleep, high amplitude Coma is not deeper sleep very slow, low amplitude waves Sleep Sleep stages marked by types of waves Slowwave sleep defined by percent of delta waves Stage 3 and stage 4 sleep (caveats) Sleep ‘rhythm’ NREM (75%) vs. REM (25%) Changes with age Babies have a lot of REM (80%) Old people have shorter sleep and less REM Stage 4 (delta waves) is restorative sleep REM sleep Can’t move during REM sleep Vivid dreams happen during this stage Lack of core muscle tone 09.28.15 Neuropsych Lecture Brain damage 2 Inflammation Normal response to harmful stimuli Vasodilation (redness/warm) Tissue swelling Edema fluid buildup (can cause drowsiness or loss of consciousness) Cell infiltration o Cells of the immune system Pain Loss of function Signs of inflammation Dolor pain Rubor redness Tumor swelling Calor warmth Funciolasa broken function Vascular changes (early after injury, depends on severity of injury) Vasodilation leads to increased blood flow causing redness and warmth Increased permeability leads to exudation of protein rich fluid into the extravascular space causing swelling Concentration of red cells caused by loss of fluid from vessels; results in decreased velocity and stasis of blood flow Leukocyte rolling, adhesion and migration leads to accumulation of inflammatory cells Traumatic brain injuries (TBI) Penetrating/open head injuries (through skull and meninges) Closed head injuries A concussion is a TBI (mild) 80% of hospital admissions for head injury are mild TBI (mTBI) In high school athletes: 15% of all evaluated sportrelated injuries are concussions Less than 50% of concussions are reported, so that percentage will likely rise Coup brain damage at site of blow Contrecoup brain damage opposite to site of blow Coupcontrecoup brain damage on both sites Hemorrhage an escape of blood from a ruptured blood vessel Can cause a hematoma a solid swelling of clotted blood Edema and the inflammatory cascade Diffuse axonal injury damage in the form of extensive lesions in white matter tracts occurs over a widespread area. One of most common and devastating types of TBI. Caused by rapid acceleration or deceleration of the brain (as in motor accidents). Axons are disrupted Concussion symptoms Observed Can’t recall events prior to or after a hit or fall Appears dazed or stunned Forgets an instruction, is confused about an assignment or position, or is unsure of the game, score, or opponent Moves clumsily Answers questions slowly Loses consciousness (even briefly) Shows mood, behavior, or personality changes Reported Headache or “pressure” in head Nausea or vomiting Balance problems or dizziness; double or blurry vision Bothered by light or noise Feeling sluggish, hazy, foggy, or groggy Confusion; concentration or memory problems Not feeling right or feeling down Assessing the damage: Glasgow coma scale Scale 315 Eye, verbal, motor responses Classification brain injury Severe with GCS 38 Moderate GCS 912 Mild GCS 1315 Assessing the damage Loss of consciousness and length of amnesia Postconcussion syndrome a set of symptoms that may continue for weeks, months, a year or more after a concussion Chronic traumatic encephalopathy a progressive degenerative disease found in athletes (and others) with a history of repetitive brain trauma Secondimpact syndrome brain swells rapidly and catastrophically after a person suffers a second concussion before symptoms from an earlier one have subsided Adolescents especially… Adolescents’ brains more sensitive than children or adults Don’t want to stand out Don’t want to be benched ImPACT testing test adolescents take before being admitted back on athletics after having brain damage ‘Stroke’/Cerebrovascular Accidents Anoxia vs. hypoxia Anoxia no oxygen in your blood Hypoxia not a lot of oxygen in your blood (ex. at high altitudes) Ischemia vs. infarction Ischemia not a lot of blood flow to the tissue (eventually results in anoxia) Infarction no blood flow to tissue (leads to heart attack) Cerebrovascular accidents (including cerebral infarction) Stroke not enough oxygen supply to the brain Transient ‘strokes’ don’t count as CVA Transient ischemic attack (TIA) Anterior circulation: temp clumsiness, weak limbs, aphasia (speech problems) Posterior circulation: dizziness, double vision, numb or weak extremities Cerebrovascular Accidents Causes of CVA blockage of brain artery (or arteries) Clot (i.e. thrombus) clump of coagulated blood Embolus (air bubble or some other particle) typically a substance that travels in blood until it creates a blockage Symptoms Sudden reduction or loss of: Consciousness Sensation (numbness, vision problems) Voluntary movement F.A.S.T. face (symmetry), arms (holding both up), speech, time (get to hospital asap) Other vascular problems possibly leading to CVA Aneurysms bloodfilled balloonlike bulge in a weakened blood vessel wall Hemorrhages rupture in a blood vessel Intracerebral Subarachnoid 10.21.15 Neuropsych Lecture Epilepsy Primary symptom: seizures Not all seizures are a result of epilepsy (ex. brain damage, tumors) Epileptics have seizures generated by their own brain dysfunction Prevalence: 14% of the population for whom there will be multiple seizure episodes (but 1:20 will have a mild, insignificant seizure once) Difficult to diagnose due to the diversity and complexity of epileptic seizures Old classification Grand mal Loss of consciousness and equilibrium Tonicclonic convulsions Rigidity (tonus) and jerking (clonus) Resulting hypoxia may cause brain damage Petit mal Not associated with convulsions A disruption of consciousness associated with a cessation of ongoing behavior New classification Partial seizure does not involve the whole brain Generalized seizure involves the entire brain Seizure phases/types Phases: Aura can have weird sensations (touch, vision, smell, hearing) Seizure Postictal regain consciousness but confused and tired Types of symptoms: Tonic rigidity Clonic jerking motions Tonicclonic rigidity and jerking motions Myotonic tremors Atonic no tone at all; collapse (more common in children) Partial seizures Simple no alterations in consciousness (only changes in sensory or motor) Complex altered awareness and sensory/motor symptoms Secondarily generalized seizure begins in one place and spreads via thalamus “Jacksonian march” (after Hughlings Jackson, 1870) Originates in cortical region controlling the moving body part Diagnosis Seizure careful history, what type of seizure was it? Tests: EEG electroencephalogram, blood work, scans Differential diagnosis i.e. ruling out other conditions: Syncope Narcolepsy Migraines Panic disorder Determine what type of seizure disorder Decide on therapy Neuronal columns in the cortex Each column consists of several laminae Neurons in a given column have similar properties E.g. in the somatosensory cortex, all the neurons within a given column respond to stimulation of the same area of skin Brodmann’s map Cytoarchitectonic map based on organization, structure, and distribution of cortical cells BA 17 (Brodmann’s area, # of area in brain) Vision Cornea does 80% of refraction of light that comes in Iris controls pupil size, pupil is like a hole through which light comes in Lens does rest of light refraction; can change shape Vitreous humor is liquid in the eyeball Sclera is the white case of the eye Fovea area with a lot of receptors Retina has 3 cell layers Ganglion cell layer Bipolar cell layer (horizontal cells and amacrine cells) Photoreceptor layer (rods and cones take in the light) 10.25.15 Neuropsych Lecture The Senses Most of your knowledge comes from senses Information comes through light waves, air pressure changes, chemicals in air or liquid, and mechanical forces acting on the body What you perceive is compiled by your perceptual system General organization of sensory systems 1. Sensory receptors 2. Neural relays 3. Central representations in the neocortex Sensory receptors 1. Receptors only respond to a range of stimuli Sensory receptors respond to narrow band of energy Some respond only to certain shape molecule Transduction 2. Receptors transduce energy Vision: light energy chemical energy in photoreceptors APs (action potentials) Audition: air pressure mechanical energy auditory receptors APs Somatosensory: mechanical energy mechanoreceptors APs Taste and olfaction: chemicals fit into receptors APs Pain: tissue damage release of chemical acting on pain fibers APs Sensory receptors characteristics 3. Receptive fields locate sensory events 4. Receptors allow identification of change and constancy Rapidly/slowly adapting receptors 5. Receptors allow distinction between self and other Exteroceptive/interoceptive receptors Exteroceptive perceive body’s position, motion, and state Interoceptive perceive sensations in internal organs 6. Receptor density determines sensitivity Neural relays 1. Relays determine the hierarchy of motor responses 2. Message modification takes place at relays ex. impulses descending from cortex can block or amplify pain signals at level of brainstem or spinal cord 3. Relays allow sensory interactions Central representations in neocortex 1. Sensory information is coded 2. Each sensory system is composed of subsystems 3. Sensory systems have multiple representations You rub your toe after stubbing it in the dark. Rubbing the toe leads to “gating” of the pain signal, where descending fibers from the cortex block the pain signal. Nonpainful input around a pain receptor closes the gates to the pain signal which prevents pain sensation from traveling to CNS 10.19.15 Neuropsych Lecture Why do we sleep? Memory processing, recuperation, adaptation, or all of them? What are the effects of sleep deprivation? Increased sleepiness and faster sleep onset Poor mood Poor vigilance Poor executive function Physiological: body temp down, blood pressure up, immune function down, hormonal changes, metabolic changes Circadian Rhythm Suprachiasmatic nucleus (SCN) in hypothalamus Lightentraining sunlight makes cycle adjust Melatonin (pineal gland) Manipulating sleep 90 minute cycles 20 minute naps are ideal Find out if you’re a long or short sleeper Alcohol decreases sleep onset Polyphasic sleep 20 min nap every 4 hours Insomnia most common sleep disorder Incidence 1 in 4 adults Various kinds trouble falling asleep, trouble staying asleep Various medications Sleep hygiene Go to bed at the same time every night Melatonin helps Magnesium citrate helps Sleep disorders Sleep apneas Obstructive (most cases) incidence 34%; tongue relaxes and blocks airway Central (rare) CPAP/EPAP continuous positive airway pressure; excretory positive airway pressure Narcolepsy Excessive daytime sleepiness Sleep attack, cataplexy, hypnagogic hallucination (from wakefulness to sleep), sleep paralysis Incidence: 2045/100,000 Types With cataplexy lack of tone in core muscles (collapsing) Without cataplexy Result of medical condition 10.26.15 Neuropsych Lecture Visual pathways Photons converted to neuronal signals Geniculostriate pathway most important Axons convey information to lateral geniculate nucleus (LGN) in thalamus Information then relayed (via optic radiations) to striate cortex Striate cortex = primary visual cortex = V1 = BA 17 Tectopulvinar pathway phylogenetically older Eye to superior colliculus to pulvinar in thalamus then to visual areas in temporal and parietal lobes Each visual field is perceived by only one cerebral hemisphere Optic chiasm crossover point for optic nerve fibers (nasal fibers only) Results in contralateral projections of information from nasal ganglion cells Ipsilateral same side for temporal processing Contralateral opposite side for nasal processing Nasal hemiretina has nasal ganglion cells Temporal hemiretina Retinotopic presentation places on retina where information Striate (primary) cortex Different neurons respond to different stimulus attributes E.g. orientation and movement simple and complex cells Visual association cortex Integrates information from primary visual cortex Information flow: Primary cortex striate occipital cortex (BA 17) Secondary cortex extrastriate occipital cortex Tertiary cortex inferior temporal and posterior parietal cortex (and STS) Two “streams” from secondary to tertiary: Dorsal stream Ventral stream Processing areas MT (V5) motion V4 color Ventral Fusiform face area face analysis Fusiform body area Parahippocampal place area interested in scenes/views Dorsal Anterior intraparietal sulcus object directed grasping 10.28.15 Neuropsych Lecture Disorders Optic tracts: fundamental visual sensation Blindness (partial or complete) Hemianop(s)ia blindness in one side of visual field Parts of visual field missing E.g. scotoma V1 up: higherorder disorders of construction, space, and meaning Disorders in occipital lobe Disturbances involving ventral and dorsal streams Disorders in occipital cortex Akinetopsia Inability to identify objects in motion, very rare Cerebral achromatopsia Loss of ability to detect color Hemiachromatopsia Loss of ability to detect color on only one side Hearing Sound transmission Pinna flaps on ears catch sound waves and funnel them to external auditory canal Ear drum vibrates when sound waves hit it Hammer, anvil, stirrup (middle ear) Cochlea Receptors Basilar membrane in cochlea Hair cells N. VIII The nerve with many names in charge of hearing and vestibular sense Sound entering each ear is processed by both the ipsilateral and contralateral hemisphere Primary auditory cortex A1, or Heschl’s gyrus/i, or Brodmann’s 41 and 42, or transverse temporal gyri Temporal lobe anatomy & connections Superior temporal gyrus Middle temporal gyrus Inferior temporal gyrus Superior temporal sulcus (STS) between superior and middle temporal gyri Five main types of connections: 1. Hierarchical sensory pathway 2. Dorsal auditory pathway 3. Polymodal pathway 4. Medial temporal pathway 5. Frontal lobe projection Connections of the temporal cortex 1. Hierarchical sensory pathway From primary and secondary auditory and visual cortical regions lateral temporal cortex terminate in temporal pole (BA 38) Visual travels through inferior temporal gyrus Auditory travels through superior temporal gyrus (STG) Then relayed to the medial aspects of the temporal lobe 2. Dorsal auditory pathway Connections with the posterior parietal cortex Effects: Enables location of sounds in space Promotes orienting and initiation of movements relative to sound location 3. Polymodal pathway to STS Connections emerging from the auditory and visual hierarchical pathways Directed to neurons enfolded within the superior temporal sulcus Polymodal region i.e. multiple sensory modalities Believed to be involved in assigning stimuli to categorical classes 4. Medial temporal projection pathway Major destinations: Amygdala and hippocampus This results in the integration of information into memory and emotional tone Direction of projections: Perirhinal cortex Entorhinal cortex amygdala/hippocampus Perforant pathway forms the main projection to the hippocampus Damage in this region severely affects memory Ultimate effect: Stimulus recognition The familiar conscious experience of knowing, assimilating, and feeling 5. Frontal lobe projection Neurons from the temporal lobe have strong connections with the frontal lobe Posterior temporal cortex Projects to the dorsolateral prefrontal cortex Anterior temporal cortex Projects to the orbitofrontal cortex 11.02.15 Neuropsych Lecture Ventral visual stream Object perception Biological motion Face perception How does object perception work, possibly? Edges and bars of lengths, contrasts and orientations Grouping elements into higherorder units, separating figure and ground Viewercentered description matched onto stored 3D descriptions of structure of objects (rotation if needed) Meaning attributed to the stimulus Naming of different terms Neurons respond to increasingly complex stimuli Viewdependent vs. viewinvariant object recognition Viewdependent theories of object recognition posit that recognition processes depend on the vantage point from which the object is seen (recognizing that all four drawings depict a bicycle requires matching the distinct sensory inputs to viewdependent representations). Whole objects are stored in memory with multiple viewpoints. Requires a lot of memory Viewinvariant object recognition theories say that recognition is based on structural info or individual parts, allowing recognition to take place regardless of viewpoint. Recognition is possible from any viewpoint as long as object can be rotated to see each part of the object. Requires little memory because only parts need to be encoded Disorders of ventral stream Agnosia failure to “know” Apperceptive visual agnosia no recognition of objects Associative visual agnosia disorder of meaning (e.g. inability to name what is seen) Biological Motion Motion of biological entities Superior temporal sulcus (STS) analyzes biological motion Basis of social perception and development of social cognition STS neurons also respond to approach motions of bodies Damage to STS results in impaired recognition and recall of faces Impaired perception of subtle social signals (e.g. glances at watch or clock) Face processing Core: V1 (inferior occipital gyri), FFA (fusiform face area), STS FFA & PPA FFA fusiform face area PPA parahippocampal place area Prosopagnosia Inability to recognize faces Different levels of impairment in different people Also congenital forms in various degrees Auditory problems Impaired auditory sensation and perception Disordered perception of music Impaired language comprehension Hearing disorders (two classes): Conductive Problems in conduction of sound due to outer ear, eardrums, ear bones in middle ear Sensorineural Dysfunction of inner ear (cochlea), auditory nerve, or higher auditory processing centers Mostly dysfunction of hair cells Viruses, meningitis, measles, mumps, etc. Hearing loss can occur from infections, exposure to loud noise, and oxotoxic drugs Cochlear implant Microphone Speech processor Transmitter Receiver Stimulator 11.04.15 Neuropsych Lecture Auditory perception Paradoxically, bilateral damage to the primary cortex does not usually lead to cortical deafness Auditory hallucinations Auditory hallucinations when you hear one or more talking voices One can have auditory hallucinations without having mania or schizophrenia Research suggests that spontaneous neural activity in the auditory cortex gives rise to such hallucinations, interacting with the language areas of the temporal lobe Dierks et al (1999) Conducted fMRI on schizophrenic patients during auditory hallucinations Compared results to neural activity in response to acoustic stimuli Results: activation seen in Broca’s area, primary auditory cortex, and speech zone in posterior temporal cortex Additional limbic areas also recruited (amygdala and hippocampus) This was probably due to the engagement of memory as well as emotional responses to hallucinatory content Auditory cortex Discriminates two forms of auditory processing Rapidly presented stimuli E.g. rapid presentation of language needs to be quickly analyzed Complex patterns of stimuli E.g. music has slower changes in frequency Speech perception Speech sounds differ from other auditory input: Speech sounds come from 3 restricted ranges of frequencies (formants) Same speech sounds are different depending on spoken context but perceived as same sound. Auditory system categorizes sounds as equivalent Speech sounds change rapidly with regard to each other, and the order is crucial Patients with left temporal lobe damage have difficulty: 1. Discriminating sounds Complain that people are talking too fast E.g. like learning a new language 2. Judging the temporal sequence of heard sounds Normally, two sounds resolved within 5060 ms Damage results in 10fold increase in temporal requirement for discrimination (i.e. about 500 ms) Patients with right temporal lobe damage have difficulty understanding emotional intention of language Music perception Musical sounds Loudness Pitch Timbre Timing in music Rhythm L & other (left temporal lobe)
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