Neuro 13: Cerebral Cortex Flashcards
What are the 3 types of fibres in cerebral white matter?
- association fibres
- commissural fibres
- projection fibres
What do association fibres do?
- they connect arose within the same hemisphere
What do association fibres do?
- they connect left hemisphere to right hemisphere
What do projection fibres do?
- they connect cortex with lower brain structures, brainstem + spinal cord
What are the 6 grey matter cortical layers
6 layers
layer 1 - 3 = usually cortico-cortical connections
(2-3) you can see neurones
layer 4 = receives input from thalamus
layer 5-6 = has connections with lower cortex/braintem/spinal cord (projection fibres)
The cortex = divided into lobes.
What are the major lobes?
OCCIPITAL
PARIETAL
TEMPORAL
FRONTAL
what are the major function of the lobes?
OCCIPITAL
OCCIPITAL
- -> ventral pathway = analyses form + color
- -> dorsal pathway = spatial relationship + movement
what are the major function of the PARIETAL LOBE?
posterior parietal cortex
PARIETAL
–>(posterior parietal cortex) creates spatial map of body
Injury to parietal lobe may cause :
- disorientation
- inability to read map / understand spatial relationships
- apraxia
what is the definition of apraxia?
inability to make skilled movement with accuracy
what are the major function of the temporal LOBE?
- language
- object recognition
- memory
- emotion
lesion / Injury of temporal lobe may lead to :
- agnosia
- -> patient can’t interpret sensations correctly although organs/nerves are functioning normally
- receptive aphasia
- -> patient can’t understand language in its spoken/written form
what are the major function of the frontal LOBE?
- judgement
- foresight
- personality
Injury/ lesion of frontal lobe may lead to :
- deficit in planning
- inappropriate behavior
- attention span + concentration diminishes
- self control is impaired
Compare between primary cortices and association cortices ?
primary cortices:
- predictable function
- organized topographically
- has left right symmetry
association cortices:
- function is less predictable
- not organized topographically
- left right symmetry is weak/absent
What is prosopagnosia?
- inability to recognize faces or learn new faces
what is prosopagnosia caused by?
caused by lesion of the visual posterior association area
give an example of a method of brain stimulation.
- Transcranial magnetic stimulation (TMS)
- -> used to test whether a specific brain area is responsible for a function
- Transcranial direct current stimulation (TDCS)
- -> changes local excitability of neurones increasing/decreasing firing rate
note
Right hemisphere is = artistic + creative
left hemisphere = logical + scientific
-
How does PET scan work?
- uses radioactive tracer attached to a molecule
- -> to locate brain areas where the particular molecule (e.g dopamine( is being absorbed
note: SPECT lower resolution version
What might you see in a PET scan of a patient with parkinson’s diseases?
- there will be profound loss in the posterolateral putamen with relative preservation of the caudate
What is the difference between an EEG and a MEG
MEG = measures magnetic fields
–> maps brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain
EEG = measures electric fields
–> measures voltage fluctuation resulting from ionic current in neurons of the brain
What does the fMRI do?
- it measures the brain activity by detecting changes associated with blood flow
- relies on the fact that cerebral blood flow + neuronal activation are coupled
increased blood flow areas = more active areas
when someone imagines positive events, _____ + _____ become more active
when someone imagines positive events, amygdala + rostral anterior cingulate cortex become more active
note: grey matter also has columnar arrangement - basis of topographical organisation
-
testing function of the brain - list some methods
- fMRI
- PET
- SPECT
- light microscopy
- lesions
differentiate the two parts of the visual association cortex
- Dorsal pathway = interprets spatial relationships + movements
- Ventral pathway = responsible for form and colour
visual posterior association area lesion can cause =
prosopagnosia.
loss of connection between 2 hemispheres e.g in callosotomy cause :
lateralised deficits in function
describe the test / experiment done to test hemisphere specialization
left hemisphere = dominant for verbal processing
right hemisphere = cannot share info with left so patient can’t say what it is but can draw out what it is.
TMS (transcranial magnetic stimulation)
how does it work? and what for?
- magnetic field induces electric current in cortex –> causes neurons to fire
- used to test whether specific brain area = responsible for a function e.g speech.
Transcranial direct current stimulation (TDCS)
- change excitability of neurones –> increasing/decreasing firing rate
What type of neurone is found in layer 4 ?
- Stellate neurone
What type of neurone is found in layer 5?
- Pyramidal neurones
What could happen after prefrontal lobotomy?
- Change in behaviour
- Increased aggression
- Change in personality
- Inappropriate behaviour
- Diminished attention / concentration span
what are the consequences of a unilateral parietal lobe lesion?
- hemispatial neglect
can only draw half
callosotomy may be carried out to treat _______
seizures
Which areas of the brain become more active when participants imagine positive events?
- Amygdala
- Rostral anterior cingulate cortex
define the neocortex
- Part of the cerebral cortex concerned with sight and hearing
