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Year 2 LCRS > Neurology 18 - Cerebral Cortex > Flashcards

Neurology 18 - Cerebral Cortex Flashcards

1
Q

List the fibre types present in cerebral white matter

A
  • Association fibres (connect areas within the same hemisphere)
  • Commisural fibres (connect the left to the right hemisphere - corpus callosum, anterior and posterior commisural)
  • Projection fibres (connect the cortex with lower brain structures, brain stem and spinal cord - corticospinal tract)
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2
Q

What is present in the different layers of the grey matter in the cortex?

A

Dorsal (outside)
- Layers 1 to 3 are mainly cortico-cortical connections (association). Layer 1 has few cells.
- Layer 4 is input from the thalamus
- Layers 5 and 6 are connections with subcortical, brainstem and spinal cord (output layers - Betz cells)
Ventral (inside)

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3
Q

How is the neocortex arranged?

A
  • In layers (amina) and columns
  • More dense vertical connections (basis for topographical organisation)
  • Neurons with similar properties are connected in the same column
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4
Q

List the lobes of the neocortex

A
  • Occipital
  • Parietal
  • Temporal
  • Frontal
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5
Q

What is the function of the occipital lobe?

A
  • Visual association cortex analyses different attributes of visual image in different places
  • Form and colour analysed along ventral pathway, spatial and movement along dorsal pathway
  • Lesions affect visual perception
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6
Q

List the functions of the parietal lobe

A
  • Posterior parietal association cortex creates spatial map of body in surroundings, from multi-modality information
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7
Q

List the functions of the temporal lobe

A
  • Language, object recognition, memory, emotion
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8
Q

List the functions of the frontal lobe

A
  • Judgement, foresight, personality, appreciation of self in relation to world
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9
Q

Compare the primary and association cortices

A

Primary

  • Function is predictable
  • Organised topographically
  • Left-right symmetry

Association

  • Function less predictable
  • Not organised topographically
  • Left-right symmetry is weak or absent
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10
Q

List the primary cortices

A
  • Primary motor cortex
  • Primary somatosensory cortex
  • Visual cortex
  • Auditary cortex
  • Gustatory cortex (taste)
  • Olfactory cortex (smell)
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11
Q

List the association cortices and their functions

A
  • Primary motor cortex + motor association area (skeletal muscle movement)
  • Primary somatosensory cortex and sensory association area (sensory from skin, muscoskeletal, viscera and taste buds)
  • Visual association cortex (vision)
  • Auditory association area (hearing)
  • Prefrontal association area (coordinates information from other association areas, and controls some behaviours)
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12
Q

What is the result of lesion in the visual posterior association cortex?

A
  • Image attributes are processed separately (localisation in space is dorsal stream, and visual identification is ventral stream)
  • Lesions result in inability to recognise familiar faces or learn new faces (prosopagnosia)
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13
Q

What is the result of frontal cortex lesions?

A
  • Lack of planning
  • Behaviour becomes disorganised
  • Attention span and concentration diminish
  • Self control is impaired
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14
Q

What is the result of parietal cortex lesions?

A
  • Disorientation
  • Inability to read maps or understand spatial relationships
  • Apraxia
  • Hemispatial neglect (don’t see one of the sides)
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15
Q

What is the result of lesions in the temporal cortex?

A
  • Agnosia (inability to recognise things)

- Receptive aphasia (impairment of language)

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16
Q

What is seen in patients who have had a callosotomy?

A
  • Split brain (can be born without a corpus callosum)
  • Lateralised deficits in function
  • Some processes are hemispheric
17
Q

Explain hemispheric specialisation

A

The left hemisphere is language dominant, and the right is largely spatial processing

18
Q

What is used to measure the effect of lesions?

A
  • Structural imaging

- Tractography (diffusion tensor imaging)

19
Q

What is the function of transcranial magnetic stimulation?

A
  • Magnetic field induces an electric current in the cortex, causing neurons to fire
  • Can be used to test whether a specific brain area is responsible for function
20
Q

What is the effect of transcranial direct current stimulation?

A
  • Changes local excitability of neurons

- Increases or decreases the firing rate, but does not directly induce neuronal firing

21
Q

What could transcranial direct current stimulation be used to treat?

A
  • Motion sickness

- By suppressing the area of the cortex associated with processing vestibular information

22
Q

Describe the process of positron emission tomography (PET)

A
  • Uses a radioactive tracer attached to a molecule to locate brain areas where that particular molecule is being absorbed in the brain
  • Expensive, but with good spatial resolution and specificity
23
Q

Describe the process of magnetoencephalography (MEG)

A
  • Functional neuroimaging technique for mapping brain activity by recording magnetic fields produced by electrical currents occuring naturally in the brain
  • Uses sensitive magnetometrs
24
Q

Describe the process of electroencephalography (EEG)

A
  • An electrophysiological monitoring method to record electrical activity of the brain.
  • Typically noninvasive, with the electrodes placed along the scalp, although invasive electrodes are sometimes used in specific applications (intracortical EEG, for example to localise function during neurosurgery).
  • Measures voltage fluctuations resulting from ionic current within the neurons of the brain
25
Q

What can MEG and EEG not measure?

A

The activity of interior structures - they can only measure the surface activity of the brain

26
Q

What is the issue with MEG/EEG?

A
  • Noisy signals

- A large number of trials must be performed so an average can be used

27
Q

Describe the process of functional magnetic resonance imaging

A
  • Measures brain activity by detecting changes associated with blood flow
  • Relies on the fact CBF and neuronal activation are coupled - more activity = more blood flow
28
Q

How is optimism measured?

A
  • Measure brain response to imagining positive and negative events in the future or past
  • fMRI

Year 2 LCRS (128 decks)

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