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sensory systems > somatosensory pathway and cortex > Flashcards

somatosensory pathway and cortex Flashcards

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1
Q

wat are the two basic ascending pathways from neurons to cortex?

A

-one is specialised for pain and temperature
-one is specialised for touch and joint sense

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2
Q

which receptors are responsible for touch and joint sense?

A

low threshold mechanoreceptors

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3
Q

what did vesalius do?

A

described the complete anatomy of the human body as far as the eye can see it

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4
Q

spinal nerves

A

axons that innervate each of your somatosensory receptors coalesce into large bundles called nerves
Where they exit or ender the spinal nerve

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5
Q

what does each spinal nerve do?

A

innervate a particular area of the body

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6
Q

how many spinal nerves do humans have??

A

31 pairs

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7
Q

the spinal nerve splits into two sections near teh spinal cord, what are these?

A

the dorsal root and the ventral root

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8
Q

ventral root contains

A

motor neuron efferents

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9
Q

dorsal root contains

A

sensory afferents

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10
Q

dorsal root ganglion

A

cell bodies of primary sensory fibres
swelling in the spinal nerve

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11
Q

grey matter

A

where the cells bodies are predominantly located

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12
Q

white matter

A

heavy concentration of myelinated axons

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13
Q

morphology of dorsal horn

A

granular- cell bodies are small

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14
Q

morphology of ventral horn

A

cell bodies are large

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15
Q

hypothesis for different cell bodies sizes in ventral and dorsal horn?

A

hypothesised that these differences are likely to have important functional correlates
so they divided the grey matter up into different local regions depending on cell morphology

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16
Q

two divisions of the grey matter

A

dorsal horn and ventral horn

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17
Q

rexed’s laminae

A

split grey matter into 9 regions based on cell morphology

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18
Q

rexed’s laminae dorsal horn divisions

A

lam 1-6

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19
Q

rexed’s laminae transition zone laminae

A

lam 7

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20
Q

rexed’s laminae ventral horn laminae

A

lam 8 and 9

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21
Q

rexed’s laminae temp/ nociception laminae

A

lam 1-2 (and 5)

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22
Q

rexed’s laminae skin-touch laminae

A

lam 3-5

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23
Q

rexed’s laminae joint position laminae

A

lam 6

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24
Q

what fibre types synapse in the spinal cord

A

all fibre types

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25
touch/ proprioception fibres synapse in the spinal cord and...
send direct collaterals to the brain
26
what are tracts/ columns?
Neurons in the spinal cord send their axons towards the brain, and these axons coalesce into nerve bundles called tracts/columns
27
which column does touch and proprioception information go through?
dorsal column
28
what can the dorsal column be split into?
gracile facile and cuneate fasicle
29
gracile fascicle receive information from
the legs and lower trunk
30
cuneate fascicle receives information from
the upper trunk and arms
31
which column does the nociceptive and touch information run through?
the anterolateral columns e.g., spinothalamic tract
32
what pathway is the anterolateral column a part of?
the anterolateral pathway
33
what pathway is the dorsal column a part of?
teh dorsal column medial lemniscus pathway
34
what is the dorsal column pathway?
axons in the dorsal column terminate in the medulla oblongata
35
what are the two constituent parts of the brainstem
medulla oblongata and pons
36
what is the trigeminal nuclei sensitive to?
touch on the face
37
what three nuclei do we have a complete representation
trigeminal nuclei cuneate nuclei gracile nuclei
38
where do the trigeminal, cuneate and gracile nuclei project their axons to?
ribbon like structure: medial lemniscus
39
what does the medial lemniscus do?
takes tactile stimulus to the thalamus
40
two divisions of the thalamus involved in somatosensation
ventroposterior lateral nucleus (VPL) ventroposterior medial nucleus (VPM)
41
where do thalamic neurons project to?
the somatosensory cortex
42
where is the somatosensory cortex located?
on the post central gyrus
43
summary of the dorsal column medial lemniscus pathway
mechanoreceptors dorsal root ganglion dorsal columns medial lemniscus Ventroposterior lateral nucleus (VPL- thalamus) primary somatosensory cortex
44
supragranular cortical layers
layers 1-3
45
granular cortical layers
4
46
infragranular cortical layers
5-6
47
cortical layer 4 projects to
cortical layer 2/3
48
cortical layer 2/3 projects to
cortical layer 5/6 cortex
49
cortical layer 5/6 projects to
subcortex
50
where do axons from the somatosensory thalamus terminate?
cortical layer 4
51
what did Brodmann do?
Brodmann noticed the layered staining pattern was different in different parts of the cerebral cortex Noted these anatomical differences are have functional differences Made brodmann's map, based on cytoarchitecture
52
how many areas are there in Brodmann's map?
around 40
53
how many Brodmann areas do the VPL and VPN project to?
about 4 areas Area 1, 2 , 3a, 3b located in the postcentral gyrus
54
DR wilder penfield
Operating on people to treat epilepsy Localised location in the brain from which the epiliectiform activity originates, aimed to treat by removing this focus Electrically stimulated different parts of the surface in conscious patients, could see where the epilepsy was coming form, and also parts of the brain that controlled important functions, such as speech He also made important discoveries about how the cortex is organised
55
what feeling was reported when parts of teh postcentral gyrus were stimulated?
typically reported a tingling sensation in some part of their body
56
what was the resolution of penfield's data?
only 1mm
57
what was the resolution of penfield's data?
only 1mm
58
what type of map is the homunculus?
topographic map somatotopic map
59
method of electrophysiological recording on anesthetised animals
put in microelectrodes into different parts of the post central gyrus Gently stimulate different parts of the body as you record response from the neuron Receptive field of the neuron is the part of the body that field represents
60
how did body maps produced by animal experiments relate to penfield's data?
on a coarse scale, penfields data seemed very accurate as the same sequence was observed
61
what did high resolution somatotopy reveal in the finger? what is this consistent with?
there is a second representation of the body in the postcentral gyrus which coincides with brodmanns areas 3b and 1
62
what did fMRI bold responses show?
fMRI data is consistent with Brodmanns map humans have 4 maps of the body in postcentral gyrus, corresponding to the 4 brodmanns areas
63
what did monkey electrophysiology studies show?
different parts of the body represented at different spatial resolutions (homunculus)
64
magnification factor
area of teh cortex devoted to given body part by its skin area
65
what are different magnification factors caused by?
Large differences in the number of neurons devoted to different parts of the body
66
magnification factor of vibrissae
high
67
behaviourally important parts of the body
lips for language hands for object manipulation
68
relationship between magnification of body parts and receptive field size
inverse relationship small receptive field = large magnification
69
discrimination threshold
determined by 2 point discrimination task threshold is low where magnification factor is high and receptive fields are small

sensory systems (17 decks)

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