Neuro notes (Karlie Harris) PDF

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Neuro notes; 

key leaders in speech and language - Norman Geschwind (neuro focussing on disorders) - Noam Chomsky (syntax and components of language) - Pierre Paul Broca (1824-1880) localised human language to the left hemisphere of the brain, first to identify aphasia (i.e Brocas aphasia) - Wernicke’s model, worked on the sight of lesion on the brain - Jean Charcot (1825-1893) ‘scanning speech’ associated with MS, scanning the speech of people involved with lesion. - William Gowers surveyed dysarthria (1846-1915)

Time frame of knowledge advancement  

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During WW1 lots of head injuries, so insurgence of info - Lee Edward Travis 1927 1st to study SLP (stuttering) WW2 more progression of info, focus on rehabilitation of aphasia - 1891-1976, Penfield cortical mapping of the brain - 1959, speech brain mechanisms, subcortical speech mechanism and infantile cerebral brain plasticity - 1960-1970, advances in neurological concepts and comm disorders - 1980’s, importance of early stim and brain language developments - 1990 further advances in aphasia , TBI and language and com problems focus on cases - 21st, improvements in neuro imaging Brain imaging/neuro diagnostic models - Computerised tomography - MRI (magnetic resonance imaging) - PET (Positron emission tomography) - (SPECT) Single photon emission tomography

Nerve system review 

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CNS - Inside cranium and vertebral column - Integration and command centre PNS - Everything else - Afferent and efferent (somatic and motor) - Cranial and spinal nerves + ganglia

Classifications of neurons 

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Structural classes - Multipolar 99% moto neurons and most interneurons - Bipolar, rare, occur in some sensory organs - Unipolar (pseudo unipolar) typically sensory Functional - Sensory neurons (afferent) impulses from PNS -> CNS - Motor neurons (efferent) - Interneurons

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Neuroglia - Majority of nervous system - Glial cells don’t send impulses, supportive function - Important - 4 in CNS 1. Astrocytes 2. Oligodendrocytes 3. Microglia 4. ependymal - 2 in PNS 1. Schwann cells 2. Satellite cells

Action potential recap

Topic two, nervous system cortical divisions

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- Gray matter= cell body highly nucleated (thalamus, basal ganglia) - White matter _ myelinated axon Cerebrum ( 3parts) 1. Two cerebral hemisphere connected by corpus collosum 2. Basal ganglia 3. Limbic lobe (rhinencephalon) Landmarks on lobes - Gyri/gyrus - Sulci/sulcus

homeostatic imbalances of CNS - MS

Lobes Frontal lobe 1/3 of hemisphere 

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Boundaries - Anterior, lateral sulcus (Sylvania fissure) - Posterior boundary, central sulcus (rolandic fissure) - Prominent gyrus, precentral gyrus comprises primary motor cortex area 4 (motor strip) - Pyramidal tract descends from primary motor cortex into brain + spinal cord (voluntary control of skeletal muscles to contralateral side of the body Homunculus of cerebral cortex

Frontal lobe function - Motor skills like hand eye coord - Conscious thought - emotions - personality Common tests for frontal lobe function - Wisconsin card sorting (response inhibition) - Finger tapping (motor skills) - Token test (language skill)

Broddmans map

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- Number 44-45 is brocas area, left dominant is important for speech and language - Number 8, attention and eye movements - Prefrontal cortex - 9, 10, 11, 46, 47 frontal association - Area 6 premotor cortex and supplementary motor area Frontal lobe damage - Impaired attention span - Impaired motivation - Poor organisation and poor judgment - Dramatic change in social behaviours

Parietal lobe ‘radar of the brain’ 

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Boundaries - Anterior, central sulcus - Posterior boundary, imaginary border line - Inferior, post end of lateral sulcus - Primary sensory cortex (somatosensory/ somesthetic) (area 1.2.3) housed by post central gyrus - This sensory cortex can map sensory controls of the body - Somesthetic sensations = pain, temp, touch sent to sensory cortex form opp side of body - Mirror image of motor strip called sensory strip Two functional regions 1. Sensation and perception (cognition) 2. Integration of visual sensory input (spatial awareness) Function of parietal lobe - Lt. hemisphere = language - Rt hemisphere= spatial info & selective attention NB parietal gyri for language - Supramarginal gyrus (40) - Angular gyrus (39) Left hemisphere damage (Damage to 39) - Gerstmanns syndrome, - Word finding difficulty (anomia) - Alexia with agraphia (reading and writing_ - L &R disorientation Finger agnosia (cant recognise fingers or touch) - Acalculia (difficulty with maths and numbers) Right hemisphere - Attending difficulty - Complete neglect of contralateral side of space - Visuospatial & constructional deficits Bilateral damage - Balints syndrome - Visual attentional and motor syndrome - Inability to voluntarily control gaze (ocular apraxia) - Inability to integrate components of a visual scene (similtanagnosia) - Inability to accurately reach for an object with visual guidance (optic ataxia) Special deficits - Damage to parietal and temporal, memory & personality (particularly Rt hemisphere) - Left parietal- temporal lesions, verbal memory and ability to recall strings of numbers - Common tests for parietal lobe inc 1. Kimura box test (apraxia) 2. Two point driscrimation test (somatosensory)

Temporal lobe 

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Boundaries - Superior, Sylvain fissure - Posterior, imaginary line that forms ant line of occipital lobe - Herschels gyrus, auditory cortec, cortical centre for hearing in each hemisphere Damage to temporal lobe - Unilateral damage in auditory cortex, difficulty interpreting sound or locations or deafness in one ear - Bilateral = deafness - Damage to Wernicke’s area = Wernicke’s aphasia

Insula lobe (island of reil) -

Gidden under area where temporal, parietal & forntal lobes merge Lobe is not apart of the 4 major lobes Function, receives inputs of pain and viscero-sensory inputs Facilitate the articulation of long, complex sentences Risky decision making, moral choices Damage, difficulty producing well-articulated, fluent speech Can lead to apathy, loss of libido (sexual desire) & and inability to tell fresh food from rotten

Occipital lobe  

Function, vision, and processing visual stimuli Boundary - Small area behind the parietal lobe - Lateral surface, imaginary line rather than prominent sulci - Damage= visual confusion,, potential blindness

Cerebral connections -

Basically how the area of cerebrum connect together 1. Projection fibres, long axons of beuerons sends info to distant strutures CNS 2. Commissural fibres, connects one hemishphere to another

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3. Associated fibres Short, connected areas within lobes Long, connections between lobes

Split brain research (epileptics) Specific cortical areas 3 major divisions

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1. Primary motor projection areas - Broddmans area 4 motor areas , coord of speech, facial expression and precision in motor control 2. Primary sensory reception area - Area 1,2, & 3, bodily sensations, feelings - Auditory, olfaction 3. Association areas (80%) - Cortical motor speech association, Broca - Sensory association area, gnosis (recognition) Limbic system - Medial surface of two hemispheres - Includes oldest part of the brain (rhinencephalon ‘smell brain’) - Made up of smaller structures 1. Sub-callosal gyrus 2. Gyrus singuli 3. Isthmus 4. Hippocampal gyrus 5. Uncus

Note; because of TBIs, dysfunction of deeper structures of the cerebral hemisphere can affect critical cognitive skill, memory & emotional states thus affecting treatment plans -

Autonomic & hormonal responses of hypothalamus therefore controlled by the limbic sstem and thus highly associated with behavioural reactions shaped in limbic system Amygdala, emotions (fear) primitive response Hippocampus, memory

Other structures of the CNS 

Diencephalon - Thalamus, integration sensation in NS, speech - Hypothalamus, autonomic endocrine function, emotional behaviour, sleep, wake, drink. - Epithalamus, pineal gland (melatonin), circadian rhythms - Subthalamus, functionally part of basal ganglia may inhibit motor pathway - Pituitary gland, master gland

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Basal ganglia, Anatomy ******learn - Caudate nucleus - Putamen - Globus pallidus - Substania nigra - Subthalamic nucleus Functions - Regulating and control movement - Muscle tone - Planning & expression on motor movement - Posture reflex - Prepare motor acts Basal ganglia circuits

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Substantia nigra (black substance) - Location in the midbrain but considered a functional part of basal g, because it has reciprocal connections with other brainstem nuclei Two parts (diff connections and neurotransmitters - Pars compacta- NT dopamine - Pars reticulate- NT gamma- aminobutyric acid (GABA) Parkinsons is the reduction of Substania nigra function

Subthalamic nucleus 

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About - Anatomically part of the diencephalon - Functionally part of the basal ganglia - Receives messages and sends, uses excitatory NT glutamate - Is the inhibition of thalamic override Associated disorders Hyperkinesia & Huntington’s chorea

Cerebellum -

Two hemispheres Controls movements on ipsilateral side (same) Fine coordinated movements Postural stability Damage, ataxic dysarthria Friedrerich’s ataxia

Brain stem 

Midbrain - Way to central auditory nerve and visual nerve system

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Pons - Connects two hemisphere of cerebellum, Medulla oblongata - W pyramids - Are formed by crossing motor fibres from precentral gyrus of frontal lobe and spinal cord Spinal cord -

Week 2: organisation of the nervous system part 2 PNS recap, 

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Cranial nerves with roots and rami (branches) Peripheral (spinal) nerves Peripheral aspects of ANS Peripheral ganglia- lie outside CNS

Spinal peripheral nerves - Mixed nerves (sensory and motor fibres) - Connected to spinal cord by two roots 1. Anterior root 2. Posterior root - Both sensory & motor roots leave spinal cord at intervertebral foramina roots units to form spinal nerve= mixed nerve Anterior roots - Bundles of fibres transmit impulses away from CNS (efferent) - Efferent fibres to muscles = motor fibres - Motor fibres of spinal nerves originate from anterior (ventral) horn cells Posterior roots - Afferent (sensory) fibres info carried to CNS - Cell bodies = swelling on the post root of spinal nerve- post. (dorsal) root ganglion 1. Sensation 2. Touch 3. Pain 4. Temp 5. Vibration

Cranial nerves -

7 out of the 12 relate to speech production and hearing Cranial nerves exit brain & pass through foramina of skull sense organs or muscles of necj & face Cranial nerves attached to brain at irregular intervals No dorsal or ventral roots Some have motor, some sensory, or mixed The following cranial nerves have dedicated sensor ganglia originating from the neural crest during embryonic development;

1. 2. 3. 4. 5.

Trigeminal nerve (V) Facial nerve (VII) Glossopharyngeal nerve (IX) Vagus nerve (X) The vestibulocochlear nerve (VIII)

Autonomic nervous system (ANS) -

Involuntary innovation Distributed through CNS & PNS Sympathetic (fight or flight) & parasympathetic divisions (rest & digest) Heart Smooth muscle Glands, vital for hormone secretion Visual reflexes Blood pressure controls

*ANS only indirect action on speech. Language & Hearing 

visceral vs somatic - similarities, 1. lower motor neurons (LMN)= common pathway links brain and skeletal muscles fibres (somatic)

2. sympathetic & parasympathetic= final neural pathway from CNS to visceral effectors differences 1. preganglionic neurons, cell body in brainstem or spinal cord project myelinated preganglionic fibres to autonomic ganglion 2. postganglionic neurons, cell body in ganglion sends un-myelination axon to smooth muscle enteric nervous system - neuronal plexus of gastrointestinal tract (GIT) - considered a division of ANS - direct effect on deglutition -

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protection & nourishment of brain p- pia mater a – arachnoid mater d – dura mater ventricular system

Blood supply of brain -

brain uses approx. 20% of bodies blood 02 of body initially 4 main arteries supply brain, 2 large internal carotids 2 vertebral

Circle of willis Arteries making up Circle of Willis •

Ant,. Communicating

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Ant. Cerebral

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Internal carotid

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Post communicating

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Post. Cerebral

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Basilar arteries

Topic three Neuro-sensory organisation Sherrington's scheme (classification of sensation that has applications for sensory control of speech) Three broad divisions of sensory receptors 1. Exteroreceptors, mediates sight, sound , smell & cutaneous sensation (light touch pressure, itch temp! Feeling of the skin) 2. Proprioceptors, mediate deep somatic sensation beneath skin, muscle and joints. Movement, vibration and deep pain 3. Interceptors, visceral pains, distention visceral pain receptors either form cellular or tissue injury known as nociceptors Sense's classes   

Special senses, sight, hearing, balance, smell & taste General senses, remainder of senses (general visceral) Afferent interceptors monitor, PH change in blood and bladder distention

Sensory association cortices 

Visual cortex (area 17)

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Auditory (area 41 & 42) Somatosensory cortex (areas 1, 2 &3 – post central gyrus)

Agnosia

Visual agnosias  

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Capgras, see person/ item and recognise them but believe it is an imposter. Fusiform face area intact but disconnected to emotional limbic area Prosopagnosia, don’t recognise the face or item but can easily accept what it is with no suspicion. Fusiform face area is damaged (no conscious recognition) but emotionally the body responds Fregoli syndrome, believe many different people are one person just transforming their appearance or putting on a disguise . The limbic system defunct and giving same emotion to all faces.

VISUAL CORTEX (area 17)  

Entire medial surface of occipital lobe & lateral occipital surface (18 &19) Inferior surface of temporal lobe (areas 20, 21 & 37)

The optic nerve The fibres from the retina of each eye originate in two areas 1. Temporal fibres from lateral half of retina (close to temple) 2. Nasal fibres from the other half closer to nose

At optic chiasm nasal fibres from each eye cross over (decussate) while the temporal fibres continue ipsilaterally. This shift makes stereoscopic 3D vision possible The visual cortex in left hemisphere receives info about the contralateral R side and vice versa this is important to know when understanding brain injury

Optic chasm -> lateral geniculate body -> internal capsule -> lateral ventricle -> fibres over temporal horn of lateral ventricle -> fibres terminate in visual cortex below calcarine sulcus -> represent upper part of central visual field -> other fibres from geniculate body -> visual cortex above calcarine sulcus -> represent lower part of central visual field. Primary visual cortex Different receptive fields in neurons of visual cortex    

Simple, cells respond to slit of light of particular width, slant or place in retina Complex, responds to slit shaped stimuli over large area of retina Hyper-complex, line stimuli's must be particular length Higher order hyper complex, require more elaborate visual stimuli to respond

Major visual pathways * 1. Tectal (collicular) pathway  Projects to superior colliculi in the brain stem -> thalamus -> many regions of cortex also receives input from somatosensory &auditory systems  The tectile pathway, ability to orient towards & follow a visual stimulus 2. Pretectal nuclei pathway  Not all Fs go to lateral geniculate body, some project to the subcortical pretectal nuclei & ascend to the thalamus to various cortical area  Control of certain visual reflexes, pupillary reflex & certain eye movements

Visual association cortex (18 & 19) Complex aspects of visual stim such as motion, colour & form Visual integration  

The dorsal stream, directed to parietal lobe processes WHERE stim is and DIRECTION & SPEED The ventral stream directed towards temporal lobe processes stimulus SHAPE , WHAT it is and what its CALLED

AUDITORY CORTEX (AREA 41 & 42)  Areas around Heschls gyrus & area 22  Left temporal lobe (area 22) considered more of a supramodel association area than simply a polymodal processor because of language processing capabilities Cranial & brain stem levels Cochlear division CN VIII (1st order) spiral ganglion, internal auditory canal -> brainstem cerebellopontine angle -> dorsal and ventral cochlear nuclei (2nd order) drapped around inf cerebellar peduncles -> some fibres to upper medulla & pons crossing the midline. Others ascend ipsilaterally in brain stem (lateral lemniscus) -> Fs take several routes & synapse in auditory system; superior olives, inf. Colliculus & nucleus of lateral lemniscus

The superior olivary nuclei- important role in localising sound through neural response to the time & intensity differences from both ears

Lesions of the auditory system Unilateral cortical damage (deafness in one ear)

Lesions in Heschl’s gyrus = may produce cortical deafness, non verbal agnosia or auditory agnosia Pure word deafness = nonverbal stimuli can be identified but speech cannot be understood. patient cannot comprehend verbal language but usually reads, speaks & writes functionally.  In bilateral pure word deafness, the lesions in the temporal lobe spare Heschl’s gyrus.  Lesions on left assumed to cut connections between primary auditory receptor cortex & Wernicke’s area.  Lesion on right cut off the origin of the callosal fibers from the right auditory cortex.  All auditory agnosias occur in the face of normal hearing acuity. Slide 28...