Cortical Organisation & Function Flashcards

-> Organisation of the nervous system: Compare and contrast the structure of the central, peripheral and autonomic (sympathetic and parasympathetic) nervous systems -> Nervous system disorders: Summarise the pathology and pathophysiology of central and peripheral nervous system disorders.

1
Q

How is the cerebral cortex organised superficially?

A
  • Highly folded surface with gyri (pumps) and sulci (folds)
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2
Q

How are the microscopic layers of the cerebral cortex organised?

A
  • Organised into layers and columns
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3
Q

What are the total number of cytoarchitecture classifications (Brodmann classification)?

A
  • 52
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4
Q

Which cytoarchitecture regions are associated with the primary somatosensory cortex?

A
  • 1, 2 & 3
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5
Q

Which cytoarchitecture region is associated with the primary motor cortex?

A
  • 4
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6
Q

What are the four cerebral lobes?

A
  • Occipital lobe
  • Parietal lobe
  • Temporal lobe
  • Frontal lobe
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7
Q

What are the main signs of cerebellar dysfunction (5)?

A
  • Ataxia
  • Dysmetria
  • Intention tremor
  • Dysdiadochokinesia
  • Scanning speech
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8
Q

What is dysmetria?

A
  • Inappropriate force and distance for target directed movements
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9
Q

What is intention tremor?

A
  • Increasingly oscillatory trajectory of a limb in a target-directed movement
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10
Q

What is dysdiadochokinesia?

A
  • Inability to perform rapidly alternating movements (rapidly pronating and supinating hands and forearms)
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11
Q

What is the function of the frontal lobe (4)?

A
  • Regulating and initiating motor function (Primary motor cortex)
  • Language (Broca’s area)
  • Cognitive (executive, including planning and problem solving)
  • Attention and memory
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12
Q

What is the function of the parietal lobe (3)?

A
  • Processing somatic sensations (primary somatosensory cortex)
    • Touch, pain, temperature, proprioception, fine touch and vibration
  • Sensory aspects of language
  • Spatial orientation and self-perception
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13
Q

What is the function of the temporal lobe (4)?

A
  • Processes auditory information (primary auditory cortex)
  • Comprehension and understanding of speech (Wernicke’s area)
  • Emotions
  • Memory
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14
Q

What is the function of the occipital lobe?

A
  • Processes visual information (Primary visual cortex & visual association area)
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15
Q

What four structures are connected within the limbic system?

A
  • Amygdala
  • Hippocampus
  • Mamillary body
  • Cingulate gyrus
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16
Q

Where is the insular cortex?

A
  • Resides deep within the lateral fissure
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17
Q

What five functions are concerned with the insular cortex?

A
  • Visceral sensations
  • Autonomic control
  • Interocepetion (the sense of the internal state of the body)
  • Auditory processing
  • Visual-vestibular integration (Input from balance organs)
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18
Q

What are the grey matter structures?

A
  • Neuronal cell bodies & glial cells
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19
Q

What are the white matter structures?

A
  • Myelinated neuronal axons arranged in tracts (resides deep)
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20
Q

What is the function of the association fibres?

A
  • Connect areas within the same hemisphere
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21
Q

What is the function of the commissural fibres?

A
  • Connect homologous structure in left and right hemisphere
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22
Q

What is the function of the projection fibers?

A
  • Connect cortex within lower brain structure (Thalamus, brainstem and spinal cord)
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23
Q

What are the 2 types of association fibres?

A
  • Short fibres / U-fibres (Green)
  • Long fibres (Orange / Pink / Purple / Blue)
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24
Q

What are the 4 long association fibres?

A
  • Superior longitudinal fasciculus (Pink)
  • Arcuate fasciculus (Purple)
  • Inferior longitudinal fasciculus (Blue)
  • Uncinate fasciculus (Orange)
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25
Q

What does the superior longitudinal fasciculus connect?

A
  • (Pink) Frontal lobe & Occipital lobe
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26
Q

What does the arcuate fasciculus connect?

A
  • (Purple) Frontal lobe & Temporal lobe
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27
Q

What does the inferior longitudinal fasciculus connect?

A
  • (Blue) Temporal lobe & Occipital lobes
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28
Q

What does the uncinate fasciculus connect?

A
  • (Orange) Anterior frontal lobe & Temporal lobe
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29
Q

What are the two commissural fibres?

A
  • Corpus callosum
  • Anterior commissure
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30
Q

What are the afferent projection fibres?

A
  • Fibres that project towards the cortex
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31
Q

What are the efferent projection fibres?

A
  • Fibres that project away from the cortex
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32
Q

Where do the projection fibres (corona radiata) radiate?

A
  • Radiate out from the cortex and then come together in the brain stem
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33
Q

Where does the corona radiata converge through?

A
  • The internal capsule
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34
Q

Where is the internal capsule?

A
  • Resides between the thalamus and basal ganglia
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35
Q

Where does the primary motor cortex reside?

A
  • Within the pre-central gyrus
36
Q

What is the function of the primary motor cortex?

A
  • Controls fine, discrete, precise voluntary movements
  • Provides descending signals to execute movements
37
Q

What is the function of the supplementary motor area?

A
  • Involved in planning complex movements (internally cued)
38
Q

What is the function of the premotor area?

A
  • Involved in planning complex movements (externally cued)
39
Q

What is the function of the primary somatosensory cortex?

A
  • Processes somatic sensations arising from receptors in the body (i.e. fine touch, vibration, two-point discrimination, proprioception, pain and temperature)
40
Q

Where does the primary somatosensory cortex reside?

A
  • Post-central gyrus
41
Q

What is the function of the somatosensory association cortex?

A
  • Interpret significance of sensory information e.g. recognising an object placed in the hand
  • Awareness of self and awareness of personal space
42
Q

What are the two regions associated with the occipital lobe?

A
  • Primary visual cortex
  • Visual association area
43
Q

What is the function of the primary visual cortex?

A
  • Receives visual input from the optic nerve via the optic radiations
44
Q

What is the visual association area?

A
  • Gives meaning and interpretation of visual input
45
Q

What is the function of the primary auditory cortex?

A
  • Processes auditory stimuli
  • Tonographically arranged to specific frequencies
46
Q

What is the function of the auditory association area?

A
  • Gives meaning and interpretation of auditory input
47
Q

What is the function of the prefrontal cortex (5)?

A
  • Concerned with:
    • Attention
    • Adjusting social behaviour
    • Planning
    • Personality expression
    • Decision making
48
Q

What is the function of the Broca’s area?

A
  • Responsible for the production of language (Associated with motor regions)
49
Q

What is the function of Wernicke’s area?

A
  • Associated with comprehension and understanding of language
50
Q

What are the symptoms of a frontal lobe lesion?

A
  • Changes in personality and inappropriate behaviour
51
Q

What are the symptoms of a right parietal lobe lesion (3)?

A
  • Contralateral neglect (Hemispatial)
    • Lack of awareness of self on left side
    • Lack of awareness of left side of extra-personal space
52
Q

How are the Wernicke’s and Broca’s area connected?

A
  • Via the arcuate fasciculus (from frontal and temporal lobe)
53
Q

What imaging modalities are used in assessing cortical fucntion?

A
  • PET scan
  • fMRI scan
54
Q

What does a PET scan assess?

A
  • Detects blood flow directly to a brain region associated with a particular active function, using radioactively labelled glucose (fluorodeoxyglucose)
55
Q

What does a fMRI assess?

A
  • Assesses blood oxygenation in a particular brain region (determines the increase in oxygen being delivered to a region of the brain implies increased activity)
56
Q

What is an Encephalography (EEG)?

A
  • Measures the electrical signals produced by the brain frequently used in the diagnosis of epilepsy and sleep disorders
  • Event-evoked potentials:
    • Used to ascertain where the signal is blocked
57
Q

What is an MEG?

A
  • Measures magnetic signals produced by the brain
58
Q

What is transcranial magnetic stimulation?

A
  • Assesses the functional integrity of neural circuits
    • Stimulator (magnetic) relies on the production of changing magnetic field which gives rise to electric fields obeying Faraday’s law
59
Q

What is Transcranial direct current stimulation (tDCS)?

A
  • Uses low direct current over the scalp to increase or decrease neuronal firing rates
    • Power dimes can be used to alter the firing rates of neurones
60
Q

Which imaging modality is used to assess structure of the cerebrum?

A
  • Diffusion tensor imaging - based on diffusion of water molecules
61
Q

What is DTI with tractography?

A
  • 3D reconstruction to assess neural tracts
62
Q

Which wave corresponds to a fast motor response?

A
  • M (motor) wave
63
Q

What is the H-reflex?

A
  • Induces an indirect response of the motor neurone via a monosynaptic reflex in the spinal cord
64
Q

What is an F-wave?

A
  • Later response is called the F-wave (not a reflex)
    • A large electrical stimulus can cause activation of the motor axons to conduct antidromically. These action potentials travel along the motor nerve to the spinal cord Cause lower motor neurones in the spinal cord to become activated.Action potentials in the motor axons can travel along the motor neuron to the muscle where they causemuscle contraction, a twitch.
65
Q

What is an orthodromic wave?

A
  • Wave travelling in the normal direction in a nerve fibre
66
Q

What is an antidromic wave?

A
  • Travelling in the opposite direction to that normal in a nerve fibre
67
Q

What happens when increasing the stimulus intensity to the F wave?

A
  • Results in action potential being generated antidromically
68
Q

What is the function of the limbic lobe (5)?

A
  • Concerned with:
    • Learning
    • Memory
    • Emotion
    • Motivation
    • Reward
69
Q

Where does the Broca’s area reside?

A
  • Resides within the left cerebral hemisphere in the frontal lobe
70
Q

Where does the Wernicker’s area reside?

A
  • Resides within the left temporal lobe
71
Q

What are the three white matter tracts?

A
  • Association fibres
  • Comnissural fibres
  • Projection fibres
72
Q

What are the differences between primary cortices and secondary / association cortices (3)?

A
  • Primary:
    • Function predictable
    • Organised topographically
    • Symmetry between left and right
  • Secondary / association:
    • Function less predictable
    • Not organised topographically
    • Left-right symmetry weak or absent
73
Q

What are the clinical manifestations with temporal lobe lesions?

A
  • Leads to agnosia (inability to recognise)
  • Anterograde amnesia (inability tp form new memories)
  • Aphasia
74
Q

What is anterograde amnesia?

A
  • Cannot form new memories
75
Q

What is the risk implicated in a Bilateral resection of anterior medial temporal lobe structures to cure epilepsy?

A
  • Anterograde amnesia
76
Q

What is the risk of a Broca’s area lesion?

A
  • Expressive aphasia - impaired production of speech, comprehension is intact
77
Q

What is the risk of a Wernicke’s area lesion?

A
  • Receptive aphasia - poor comprehension of speech, production of speech is maintained
78
Q

Damage to the primary visual cortex leads to what clinical manifestation?

A
  • Blindness in the corresponding part of the visual field
79
Q

Damage to the visual association area will lead to what clinical manifestation?

A
  • Deficits in interpretation of visual information e.g.prosopagnosia
80
Q

What is prosopagnosia?

A
  • Inability to recognise familiar faces or learn new faces (face blindness)
81
Q

What is spatial resolution in fMRI?

A
  • The ability to zoom in onto a specific region
82
Q

What are the research areas of TMS?

A
  • TMS can be used to modulate or downregulate overactive brain regions by interfering with transmission
    • Can reduce the onset of epilepsy
    • TMS in tinnitus patients
    • Preventative for migraine
    • Treatment in depressive disorders
83
Q

What is multiple sclerosis (MS)? What is the cause of MS? What are the symptoms of MS (6)?

A
  • An inflammatory demyelinating disease characterised by episodic neurological dysfunction of the central nervous system (brain and spinal cord)
  • It is an autoimmune disorder
  • Symptoms:
    • Blurred vision
    • Fatigue
    • Difficulty walking
    • Numbness
    • Paraesthesia throughout the body
    • Muscle stiffness and spasms
84
Q

What is the total motor conduction time (TMCT)?

A
  • Total time from primary motor cortex to muscle (MEP latency)
85
Q

What is the peripheral motor conduction time (PMCT)?

A
  • Time from spinal cord to muscle along the motor axon
    • PMCT = (M latency + F latency-1) /2
86
Q

What is temporal resolution in fMRI?

A
  • How quickly certain things are changing