Cerebral Cortex Flashcards
(59 cards)
1
Q
cerebral cortex
A
the outermost layer of the brain contains grey matter 2-3mm thick folded into gyri and sulci organised into layers and columns microscopically organised into lobes macroscopically
2
Q
lobes of the brain
A
frontal temporal parietal occipital limbic insular
3
Q
functions of frontal lobe
A
regulating and initiating motor function language executive cognitive function attention memory
4
Q
functions of parietal lobe
A
sensation (touch, pain)
sensory aspects of language
spatial orientation and self-perception
5
Q
functions of occipital lobe
A
processing visual information
6
Q
functions of temporal lobe
A
processing auditory information
emotions
memories
7
Q
functions of limbic lobe
A
contains: amygdala, hippocampus, mamillary body, cingulate gyrus learning memory emotion motivation and reward
8
Q
functions of insular cortex
A
lies deep within lateral fissure visceral sensations autonomic control interoception auditory processing visual-vestibular integration
9
Q
grey matter structure
A
neuronal cell bodies
glial cells
(around 85 billion of each)
10
Q
white matter structure
A
myelinated neuronal axons
arranged in tracts
11
Q
white matter tracts
A
connect cortical areas - act as a relay and coordinate communication between different brain regions
12
Q
types of white matter tracts
A
association fibres
commisural fibres
projection fibres
13
Q
association fibres
A
connect areas within the same hemisphere
can be short or long
14
Q
comissural fibres
A
connect homologous structures in left and right hemispheres
15
Q
projection fibres
A
connect cortex with lower brain structures (e.g thalamus, brain stem, spinal cord)
afferent - towards cortex
efferent - away from cortex
converge through internal capsule between thalamus and basal ganglia
16
Q
superior longitudinal fasciculus
A
association fibre that connects frontal and occipital lobes
17
Q
arcuate fasciculus
A
association fibre that connects frontal and temporal lobes
18
Q
inferior longitudinal fasciculus
A
association fibre that connects temporal and occipital lobes
19
Q
uncinate fasciculus
A
association fibre that connects anterior frontal and temporal lobes
20
Q
corona radiata
A
projection fibres that radiate from cortex to brainstem
21
Q
localisation of function
A
the theory that different areas of the brain are responsible for different behaviors, processes or activities
22
Q
primary cortices
A
predictable function
organised topographically
symmetry between left and right
23
Q
secondary/ association cortices
A
function less predictable not organised topographically left-right symmetry weak or absent
24
Q
primary motor cortex
A
frontal lobe (precentral gyrus)
controls fine, discrete, precise voluntary movements
provides descending signals to execute movements
25
supplementary motor area
frontal lobe
| involved in planning movements e.g externally cued
26
premotor area
frontal lobe
| involved in planning complex movements e.g internally cued
27
primary somatosensory cortex
```
parietal lobe (postcentral gyrus)
processes somatic sensations arising from receptors in the body e.g
fine touch
vibration
proprioception
pain
temperature
```
28
somatosensory association area
parietal lobe
interpret significance of sensory information e.g recognizing an object placed in the hand
awareness of self and personal space
29
primary visual cortex
occipital lobe
| processes visual stimuli
30
visual association cortex
occipital lobe
| gives meaning and interpretation of visual stimuli
31
primary auditory cortex
temporal lobe
| processes auditory stimuli
32
auditory association cortex
temporal lobe
| gives meaning and interpretation of auditory input
33
prefrontal cortex
```
frontal lobe
attention
adjusting social behavior
planning
personality expression
decision making
```
34
broca's area
left frontal lobe
motor functions
production of speech
connected to wernicke's area by arcuate fasciculus
35
wernicke's area
left temporal lobe
sensory functions
understanding of language
connected to broca's area by arcuate fasciculus
36
frontal lobe lesions
changes in personality
| inappropriate behavior
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parietal lobe lesions
contralateral neglect
e.g right parietal lesion will cause
lack of awareness on left side
lack of extrapersonal space awareness on left side
38
temporal lobe lesions
lateral or medial
leads to agnosia - inability to recognize
anterograde amnesia - inability to form new memories
39
broca's area lesion
expressive aphasia - poor production of speech
| comprehension intact
40
wernicke's area lesion
receptive aphasia - poor comprehension of speech
| production intact
41
primary visual cortex lesion
blindness in corresponding part of visual field
42
visual association lesion
deficits in interpretation of visual information e.g prosopagnosia - inability to recognize familiar faces or learn new faces (face blindness)
43
imaging modalities for assessing cortical function
PET - positron emission tomography
shows blood flow directly to a specific brain region
which area of the brain consumes more glucose(red)
fMRI - functional magnetic resonance imaging
shows amount of blood oxygen in a specific brain region
44
encephalography for assessing cortical function
stimulate periphery -> measure brain
measures activity (in the form of evoked potentials) produced by stimulation e.g
epilepsy/ seizures
sleep disorders
EEG - electroencephalography
measures electrical signals produced by the brain
MEG - magnetoencephalography
measures magnetic signals produced by the brain
45
evoked potentials in encephalography
potentials can be evoked:
visually - electrodes placed on the head and a visual stimulus given
somatosensorally - electrodes placed around head and back and stimulus given to median nerve on skin
produces a series of waves that reflect sequential activation of neural structures along the somatosensory pathways
46
brain stimulation for assessing cortical function
stimulate brain -> measure periphery
TMS - transcranial magnetic stimulation
uses electromagnetic induction to stimulate neurons assess the functional integrity of neural circuits
used to investigate neural interactions controlling movement following spinal cord injury
used to investigate whether a specific brain area is responsible for a function e.g speech
tDCS - transcranial direct current
uses low direct current over the scalp to increase or decrease neuronal firing rates
can make people better/worse at something by stimulating brain regions
47
imaging modalities for assessing brain function
can show damage to brain regions or tracts connecting regions
DTI - diffusion tensor imaging
based on diffusion of water molecules
DTI with tractography
3D reconstruction to assess neural tracts
48
multiple sclerosis
autoimmune disorder which results in loss of myelin from neurons in the CNS e. brain and spinal cord
49
main symptoms of MS
```
blurred vision
fatigue
dufficulty walking
parasthesia (numbness/tingling) in different parts of body
muscle stiffness
spasms
```
50
orthodromic activation
impulse travels in the normal direction in a neuron
51
antidromic activation
impulse travels in the opposite direction to normal in a neuron
52
peripheral nerve stimulation - M wave
an electrical stimulus of an appropriate intensity to a peripheral nerve can activate sensory and motor axons
activation of motor axons can cause action potentials to travel along the nerve to cause muscle contraction - a twitch - which is recorded with electromyography (EMG)
this fast response is called the M (motor)- wave and takes about 8ms
53
peripheral nerve stimulation - H wave
an electrical stimulus of an appropriate intensity to a peripheral nerve can activate sensory and motor axons
activation of sensory axons can cause action potentials to travel along the nerve to the spinal cord.
then lower motor neurons in the spinal cord become activated.
action potentials in the motor axons can travel along the motor neuron to the muscle where they cause contraction - a twitch
this a reflex activation of the muscle called an H (after Hoffmann) wave and takes about 30ms
54
peripheral nerve stimulation - F wave
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 (opposite direction)
these can activate the lower motor neurons in the spinal cord
action potentials then travel along the motor axons tro the muscle where they cause contraction - a twitch
this is not a reflex response, it is called the F wave as it was first seen in the foot and takes about 30ms
55
motor evoked potential (MEP)
motor cortex stimulated using TMS causing activation of upper motor neurons
this causes actions potentials to travel along the entire motor pathway (upper and lower motor neurons)
this causes muscle contraction, an EMG response known as motor evoked potential (MEP)
56
total motor conduction time (TMCT)
time from brain to muscle (MEP latency) about 35ms to soleus muscle
57
peripheral motor conduction time (PMCT)
time from spinal cord to muscle along motor axon:
(M latency + F latency-1)/2
the -1 is the estimated time for the action potentials arriving at the lower motor neuron cell body to turn around
58
central motor conduction time (CMCT)
TMCT - PMCT
59
effect of MS on brain stimulation and peripheral nerve stimulation
longer than usual MEP latency
problem along upper or lower motor neurons or both (unknown)
TMCT delayed
normal F wave latency so no issue with lower motor neurons
PMCT normal
therefore problem must be in CNS
