N: Cerebral Cortex Flashcards
(146 cards)
1
Q
The cerebral cortex is a sheet of ___ matter
A
gray
2
Q
Cerebral cortex is a sheet of ___
A
neurons
3
Q
What is the area of the cerebral cortex?
A
2 feet squared = area
4
Q
How thick is the cerebral cortex?
A
2-5mm thick
5
Q
How many neurons are found in the cerebral cortex?
A
25-50 billion neurons
6
Q
How many km of axons are found in the cerebral cortex?
A
100,000 km of axons
7
Q
The cerebral cortex receives ___ synapses
A
10^14
8
Q
The cerebral cortex is highly developed in ___
A
humans
9
Q
What are 3 distinct roles that the cerebral cortex plays in humasn?
A
language
abstract thinking
adapting to environment
10
Q
The cerebral cortex can be broken down into 2 subcategories. What are they?
A
- neocortex
2. allocortex
11
Q
Neocortex aka ___ aka ___
A
neocortex = isocortex = homogenetic cortex
12
Q
Why is neocortex (isocortex / homogenetic cortex) called “neo” cortex?
A
it developed later in evolution
13
Q
Neocortex makes up ___ % of cortex
A
95
14
Q
How many layers is the neocortex?
A
6
15
Q
In the neocortex, where are layers I and VI relative to the leptomeninges and white matter?
A
layer 1 is just beneath the leptomeninges
layer 6 is just on top of white matter
16
Q
Allocortex aka ___
A
homogenetic cortex
17
Q
Allocortex (homogenetic) makes up ___% of cortex
A
5
18
Q
What are the 2 types of allocortex?
A
- paleocortex
2. archicortex
19
Q
Paleocortex is ___ layers.
It overlies the ___
It plays a large role in ____
A
3 layers
overlies uncus
plays large role in olfaction
20
Q
Archicortex is __ layers
It overlies the ___
A
3 layers
overlies most of the hippocampus
21
Q
What are the 2 main types of neocortical neurons?
A
- pyramidal cells
2. non-pyramidal cells
22
Q
Which neocortical neuron is most prevalent type in humans?
A
pyramidal cells
23
Q
Describe the apical dendrites of pyramidal cells
A
1 apical dendrite per cell
extend to the top layer of the cortex (layer I)
talks to other neurons along way to layer I
24
Q
Describe the basal dendrites of pyramidal cells
A
several basal dendrites per cell
extend horizontally in respective layers (may go up or down 1 layer, but projects out laterally)
25
Describe the axons of pyramidal cells
Axons have recurrent branches to excite neighboring pyramidal cells
These axons extend from the base of the cell
26
Long axons of pyramidal cells go towards ___
other cortical areas and subcortical areas
27
Pyramidal cells are ___ synapses
excitatory (glutamatic) synapses
28
Describe the dendritic spines of pyramidal cells
preferential site for excitatory synapse
suggested to be site of synapse that are selectively modified as a result of learning
small changes in spine configuration lead to electrical properties leads to SYNAPSE EFFICACY
29
Some forms of intellectual disability may be associated with ______ (of pyramidal cells)
What are 2 examples of intellectual disabilities associated with this?
poor spine development of dendritic spines (selectively modified for learning)
examples: autism , fragile X syndrome
30
All cortical neurons that are not pyramidal cells are ___
non-pyramidal cells
31
Describe the axons and dendrites of non-pyramidal cells
Short and remain in cortical area
32
Most non-pyramidal cells are ___ synapse
inhibitory (gaba) synapse
33
The principle interneurons of the cortex are ___
non-pyramidal cells
34
Is there only 1 type of non-pyramidal cell?
no.
| they are diverse in nature (spiny stellate cell, smooth stellate cell, bipolar cell, basket cell, candle cell)
35
Spiny stellate cells are a type of ____ with spiny dendrites.
These are generally ____ synapse with ____.
receive most afferent input from ____
type of non-pyramidal cell with spiny dendrites
generally excitatory (glutaminergic) synapse w/ pyramidal cell
receive most afferent input from thalamus or other cortical areas
36
____ are the preferential site for excitatory synapses
dendritic spines
37
If most non-pyramidal cells are inhibitory (gaba) synapses, why are spiny stellate cells excitatory (glutamanergic)?
DENDRITIC SPINES ARE THE PREFERENTIAL SITE FOR EXCITATORY SYNAPSES
so SPINY stellate cells (non-pyramidal) = excitatory (glutaminergic)
38
Smooth stellate cells are a type of ____ with non-spiny dendrites.
receives _____ from pyramidal cells
silences weakly active ___ in cortex
type of non-pyramidal cells with non-spiny dendrites
receives recurrent collateral branches from pyramidal cells
silences weakly active cell columns in cortex
39
Bipolar cells are a type of ____
located mainly in ____
bipolar cells - type of non-pyramidal cell
located mainly in outer layers
40
Bipolar cells are inhibitory in nature (because non-pyramidal).
They release gaba (inhibitory) w/ co-released ___
peptides
41
"The cortex = laminar organization"
| What does this mean?
Neocortex - 6 layers horizontally
| but with vertical function
42
Cortical layer I: aka ______
What is found here?
molecular layer
ends of pyramidal cell apical dendrites
distal end of thalamocortical (intralaminar nuclei) axons
43
Cortical layer II: aka ____
What is found here?
outer granular layer
small pyramidal and stellate cells
44
Cortical layer III: aka ____
What is found here?
Outer pyramidal layer
medium sized pyramidal and stellate cells
45
Cortical layer IV: aka ___
What is found here?
inner granular layer
stellate cells receiving thalamocortical axons (relay nuclei)
46
Cortical layer V: aka ___
What is found here?
Inner pyramidal layer
large pyramidal cells to striatum and spinal cord
47
Cortical layer VI: aka ____
What is found here?
Fusiform layer
Modified pyramidal cells projecting to thalamus
48
Describe the differences between layer V of the pre-central cortex and the post-central cortex
layer V - inner pyramidal layer. this is where large pyramidal cells to striatum and spinal cord are found.
Post-central (sensory) does not need large pyramidal cells. Therefore layer V is small.
Pre-central (motor) needs large pyramidal cells so that their long axons reach the muscular output. Therefore layer V is thick.
49
What are the 5 sources of afferents to the cortex?
1. association fibers (long and short)
2. commissural fibers
3. thalamocortical fibers
4. non-specific thalamocortical fibers
5. cholinergic and aminergic fibers
50
Association fiber afferents come from ____
Are they long or short?
small and medium sized pyramidal cells
from other parts of IPSILATERAL cortex
short association fibers = from pre-central to post-central
long association fibers = from frontal lobe to occipita llobe
51
Commissural fiber afferents are from ____
From medium sized pyramidal cells via corpus callosum or anterior commisure
from corresponding CONTRALATERAL cortex
52
Thalamocortical fiber afferents are from ___
From relay nuclei or association nuclei
53
Non-specific thalamocortical fiber afferents are from ___
from intralaminar nuclei
54
Cholinergic and aminergic fibers are from ____
These afferent fibers regulate ____
basal forebrain, hypothalamus (tuberoinfundibulum), brainstem (midbrain, raphe, LC)
regulate attention and arousal
55
All efferents from the cortex are ___ cells and ___ synapses
pyramidal cells
all excitatory (glutaminergic) synapses
56
What are the 2 fiber types of efferents from cortex?
association fibers
commisural fibers
57
Efferent fibers from primary sensory cortex and primary motor cortex make up the larges part of the ___
basal ganglia
58
The ___ receives input from all of the cortex
thalamus
59
What are the main 3 efferent pathways from the cortex?
corticopontine
corticospinal
corticobulbar
60
A ___ interconnects the cerebral hemispherse
commisure
61
What is the predominant interconnection between the 2 hemispheres?
corpus callosum
62
All parts of the brain receive commissural fibers from corpus callosum except for ____
hand area of somatosensiry and motor cortex
and parts of primary visual cortex
63
The anterior commissure interconnects ______
anterior commissure interconnects the temporal lobes inferiorly
interconnects anterior olfactory nuclei
64
Disconnection syndromes as a result of white matter damage are rare. They are frequently caused by ____
strokes
65
Alexia without agraphia - disconnection syndrome via white matter damage
What are hte symptoms?
```
alexia = can't read
agraphia = can't write
```
alexia w/o agraphia = can't read but can write
can't read things even they wrote
also experience RIGHT HOMONYMOUS HEMIANOPIA
66
Association bundles interconnect ____
Different areas of the same hemisphere (different IPSILATERAL cortical areas)
67
Describe the difference between short and long association bundles
Short = u-shaped to adjacent gyri
Long = travel to different lobes
68
The longest association bundles are distinct (5). Name them.
1. superior longitudinal (arcuate) fasciculus
2. superior occipitofrontal fascicuclus
3. inferior occipitofrontal fasciculus
4. cingulu
5. uncinate fasciculus
69
The superior longitudinal (arcuate) fasciculus is a long association bundle that connects ____
frontal, occipital, parietal, temporal lobes
70
Superior and inferior occipitofrontal fasciculi are 2 long association bundles that connect ___
occipital and frontal lobes
71
Cingulum is a long association bundle that connects ____
frontal and parietal lobes to parahippocampus gyrus and adjacent temporal gyri
72
Uncinate fasciculus is a long association bundle that connects ____
frontal lobe to tempora lobe
73
Describe the difference between granular area and agranular areas of cortex
Granular area - THIN, in somatosensory (post central) gyrus
Agranular area - THICK, in motor (pre central) gyrus
74
Areas that send off long axons have more ___
pyramidal cells
75
Phineas gage = injury to frontal lobe which caused major ____ changes
personality
76
Primary motor cortex areas give rise to the ____ tract
corticospinal tract
77
Primary sensory cortex areas receive info from ____
thalamic sensory relay nuclei
78
Describe the topography of cortical sensory areas
topographical organization where body surface, range of frequencies, visual world are mapped on cortical surface
this map is distorted so that highly sensitive areas (fingers, fovea) have disproportionately large cortical representation
79
Primary somatosensory cortex aka post-central gyrus on the PARIETAL LOBE is site for _____
initial processing of tactile and proprioceptive info
80
Inferior parietal lobule is found on _______
1 hemisphere of PARIETAL LOBE
usually the left hemisphere
there is also a superior parietal lobule which is separated via intraparietal sulcus
81
Most of the parietal lobe cortex is involved in what function?
spatial orientation and directing attention
82
Primary visual cortex (striate cortex) is found ____
in the banks of the calcarine sulcus in OCCIPITAL LOBE
83
Visual association cortex of occipital lobe is involved in ____
higher order visual processing
84
bilateral injury of inferior occipital lobe leads to ____
bilateral injury of occipital-temporal junction leads to ___
inferior occipital lobe --> color blindness
occipital-temporal junction --> motion bindness
85
What is the line of gennari? Where is it?
Aka striate cortex
Thin strip of myelin in primary visual cortex
parallels calcarine sulcus and extends a little onto the posterior surface
86
Describe the visual field:
Fibers from nasal retina vs. temporal retina project to which optic tract?
This is so each ____ "sees" the contralateral visual field
nasal retina fibers --> contralateral optic tract
temporal retina fibers --> ipsilateral optic tract
this is so each optic tract sees the contralateral visual field
87
We need to be able to examine comparable areas of both retinas in order to obtain ____
This is accomplished by the ____
In order to obtain DEPTH PERCEPTION
this is accomplished by OPTIC CHIASM
88
Describe the pattern of the lateral geniculate nucleus
6 layered precise retinotopic arrangement
pattern is the same in each layer so any given point of visual field is represented as a column in all 6 layers
89
In the LGN of the occipital lobe, which layers are contralateral and which are ipsilateral?
layers 1, 4, 6 = contralateral eye
| layers 2, 3, 5 = ipsiltaeral eye
90
In the LGN of the occipital lobe, define the parvocellular vs magnocellular layers.
Parvocellular layers = color and form (layers 3-6)
Magnocellular layers = movement and contrast (layers 1-2)
91
The LGN projects to ____
How are inferior/superior visual fields perceived once there? Relative to what?
How is the macula vs peripheral field represented?
LGN projects to primary visual cortex
optic radiations end retinotopically in occipital cortex above/below calcarine sulcus
inferior visual field = superior radiations = above calcarine sulcus
superior visual field = inferior radiations = below calcarine sulcus
macula = most POSTERIORLY
peripheral vision = most ANTERIORLY
92
The primary visual cortex breaks down visual info into components such as ___
orientation, color, depth, motion, brightness
93
Once the primary visual cortex breaks down visual info into components, it distributes this info to ____
extrastriate cortex
this is an example of SIMULTANEOUS, PARALLEL PROCESSING
94
"cortex = columnar organization"
| describe this
Neurons functionally are arranged in columns that extend radially through all 6 horizontal layers
95
All neurons in each column are sensitive to _____
This is called ____
1 modality
called modality-specific
example: all neurons in 1 column respond to the movement of 1 specific joint
96
Describe the cortical modules in the foveal part of cortex
Modules here analyze small areas of visual field, so fovea has many more modules than other visual cortex
therefore it has better resolution
97
The process of dorsal/ventral streams starts in the ___
LGN
98
Which layers of the LGN go to ventral stream? Which go to dorsal stream?
What is the path there?
LGN -->
Parvocellular layers (3-6; color/form) --> ventral striate cortex --> ventral stream
Magnocellular layers (1-2; movement/location) --> dorsal striate cortex --> dorsal stream
99
Selective damage to extrastriate cortex can lead to _____
strange visual deficits (selective deficit in distinguishing colors, motion, faces)
100
Primary auditory cortex of temporal lobe is found where?
transverse temporal gyri superior surface of superior temporal gyri
101
Where is wernicke's area located?
What is it's function?
located on posterior aspect of 1 hemisphere of temporal lobe (usually left hemisphere)
this is for LANGUAGE COMPREHENSION
102
Ventral stream is located on which lobe?
What is this function?
located on ventral surface of temporal lobe
function: higher order visual processing
103
Where is Broca's area located?
What is it's function?
located on inferior frontal gyrus of 1 hemisphere (usually left)
production of spoken and written language
104
Besides broca's area, the rest of the frontal lobe is composed of ____
Responsible for ____
pre-frontal cortex
responsible for EXECUTIVE FUNCTION (personality, foresight, insight)
105
What are the motor function areas of the frontal lobe?
this is the site of origin for ___ tract
primary motor cortex
premotor area
supplemental motor area
these are the origin of CORTICOSPINAL TRACT (voluntary movement)
106
Association areas mediate _____? (function)
higher mental functions (language, arts, music)
107
Very little is known about association area functions... Most information that we do know stems from ___
case reports of patients with naturally occurring lesions
108
____ has advanced our understanding of association areas
advent of functional imaging scans
109
What are the 2 broad types of association areas?
unimodal
| multiomodal
110
Where is unimodal association cortex found?
Adjacent to the primary area that it's associated with
111
Unimodal association cortex is devoted to ____
elaborating on business of primary area it's associated with
112
Multimodal association cortex is responsible for ____ (function)
higher level INTELLECTUAL functions
113
Multimodal association cortex is found _____
inferior parietal lobule
much of frontal lobe
much of temporal lobe
114
Describe the dominant hemisphere vs. non-dominant hemispheres of the brain.
How does this relate to someone's dominant vs. non-dominant hand?
dominant hemisphere: hemisphere that produces/comprehends language (often left)
non-dominant hemisphere: usually right
THIS IS REGARDLESS OF RIGHT/LEFT HANDED
115
Cortical language areas are located near what major cortical landmark?
the lateral sulcus
116
Describe the lateral sulcus on right vs left.
Asymmetry -- which is longer? Why?
Lateral sulcus extends further posterior on LEFT than RIGHT.
Because left planum temporale is bigger on the right
(planum temporale = part of superior temporal gyrus posterior to primary auditory cortex)
117
What is the planum temporale? How does it relate to asymmetry of hemispheres?
planum temporale is part of superior temporal gyrus posterior to primary auditory cortex (it is bigger on the right than on the left)
which leads to the left lateral sulcus being longer posterior than the right.
118
Learning areas border _____ (major cortical landmark)
lateral sulcus
| usually left
119
Learning areas near the lateral (left) sulcus can stimulate ____ which results in what?
can stimulate motor cortex near mouth to produce involuntary grunts/vocalization
120
What are the Perisylvian language areas?
Brocas area
| Wernicke's area
121
Broca's are and Wernicke's area are called ____ language areas
perisylvian
122
Broca's area is located in the _____
inferior frontal gyrus (opercular/triangular part)
123
Wernicke's area is located in ____
posteiror part of superior temporal gyrus
| continuing into planum temporlae and inferior parietal lobe
124
Damage to perisylvian language areas can result in ___
aphasia
125
Describe aphasia (generally)
inability to use language
loss of use/access to words (symbols we use as concepts)
Cause by damage in wrenickes area or broca's area
126
What are the 2 main types of aphasia (and what causes them?)
nonfluent aphasia - broca's area damage
| fluent aphasia - wrenicke's area damage
127
Describe nonfluent aphasia (aka ___)
broca's aphasia
make few written/spoken words, gets by with phases "ok"
very difficult to pronounce words
all detail and meaning in sentence is lost
CAN COMPREHEND LANGUAGE
128
Describe fluent aphasia (aka ___)
Wrenicke's aphasia
can write and speak but words/sequence of words is incorrect
little to no linguistic content
can have paraphiasia (replace 1 letter/word for another) or neoglosim (make up new words)
DIFFICULTY COMPHRENDING LANGUAGE
129
# Define paraphasia.
What type of aphasia is this associated with?
paraphasia - replace 1 letter/word with another
symptom of fluent aphasia
130
# Define neologisms.
What type of aphasia is this associated with?
neologism - making up new words
symptom of fluent aphasia
131
Often, perisylvian areas are found in the left hemisphere.
Does the right hemisphere play a role in language? Describe.
Yes.
| Emotional and rythmic language is produced and comprehended in diff parts of right hemisphere
132
Define prosody
musical elements of speech
| produced/comprehended by right hemisphere
133
Prosody is produced by ____
damage = ____
right inferior frontal gyrus
damage = motor aprosody = can't convey anger/authority/etc in language
134
Prosody is comprehended by ____
damage = ____
right posterior temporoparietal region
damage = sensory aprosody = can't comprehend emotional content of others' speech
135
Association areas are found ____
in parietal cortex
| posterior to primary somatosensory cortex
136
What are the main unimodal association areas in parietal lobe?
visual, auditory, somatosensory association areas
137
Damage to parietal lobe unimodal association areas leads to _____ 3 things.
All associated with visual
remember unimodal association areas = visual, auditory, somatosensory association areas
agnosias.
```
agnosia = inability to interpret things/objects
prosopagnosia = inability to recognize familiar faces
akinetopsia = can't perceive motion
```
138
Multimodal areas of parietal lobe are centered on the ____ (cortical landmark)
main function is to ____
intraparietal sulcus
main function = monitor relationships of body with outside world
139
Left parietal lobe damage leads to _____
L parietal lobe = taking info needed to plan movement accurately
damage = APRAXIA = patient unable to perform certain planned actions.
can't REPEAT certain gestures, but can do them naturally if needs to scratch
140
Right parietal lobe damage leads to ____
```
CONTRALATERAL NEGLECT
patient has trouble w/ left half of body
some deny that something is wrong with left limb or convinced left limb belongs to someone else
ignore left half of body
trouble copy image seen on left side
```
141
Prefrontal cortex is in the frontal lobe anterior to ___
primary motor areas and supplemental motor areas
142
Prefrontal cortex controls ____
activities of other cortical areas (underlies executive function)
143
Prefrontal cortex is heavily interconnected with ____
dorsomedial nucleus of thalamus
144
There are 2 broad types of prefrontal cortex. What are they?
1. dorsolateral
| 2. ventromedial
145
Describe the dorsolateral prefrontal cortex
what does it lie over?
what is it interconnected with?
what is it's function?
over lateral convexity
interconnected with parietal association areas
important role in WORKING MEMORY, problem planning, solving problems, maintaining attention
146
Describe the ventromedial prefrontal cortex
where is it?
what does damage lead to?
extends to orbitofrontal and anterior cingulate areas
damage = makes people impulsive and can't suppress innapropriate responses/emotions
PHINIUS GAGE
