Lecture 12: Cerebrum Flashcards
1
Q
Where is cortical information housed?
A
In the gyri
2
Q
Why are the gyri important?
A
Because they are where cortical information is housed
3
Q
What is in the outer part of gray matter?
A
Cortical neuronal cell bodies extending axons to different places
4
Q
Where can cortical neurons extent their axons?
A
*From one gyrus to another
*One lobe to another
*To the other hemisphere
*Down to the spinal cord
5
Q
Where do short association fibers go?
A
From one gyrus to another gyrus in the the same lobe (or a gyrus close by)
6
Q
Where do long association fibers go?
A
From one lobe to another lobe and stay on the same side of the cortex
7
Q
Where do commissural fibers go?
A
From one hemisphere to the other (through the corpus callosum)
8
Q
Where do Projection fibers go?
A
Down the spinal cord
9
Q
What are the for types of association fibers?
A
*Short association fibers
*Long association fibers
*Commissural fibers
*Projection fibers
10
Q
What association fibres go from gyrus to gyrus?
A
Short association fibers
11
Q
What association fibres go from lobe to lobe?
A
Long association fibers
12
Q
What association fibres go from hemisphere to hemisphere?
A
Commissural fibers
13
Q
What association fibres go down the spinal cord?
A
Projection fibres
14
Q
What are the main projection fibers that go down the spinal cord?
A
*Corticospinal
*Corticobulbar
*Spinothalamic
*Dorsal Columns Medial Lemniscal
15
Q
What is the internal capsule?
A
The white matter tracts that travel between the thalamus and basal ganglia in the brain
16
Q
What are the three parts of the internal capsule?
A
Anterior Limb
Genu
Posterior Limb
17
Q
What are the parts of the basal ganglia?
A
*Caudate
*Putamen
*Globus Pallidus
18
Q
What is in the anterior limb of the Internal Capsule?
A
Thalamocortical projects (all sensory afferents except for afferents)
19
Q
What pathways are part of the thalamocortical projects that go through the anterior limb of the internal capsule?
A
*Spinothalamic tract
*Dorsal Columns Medial Lemniscus
*Trigeminothalamic tract
20
Q
What pathways are part of the Posterior Limb?
A
Corticospinal tracts for conscious movements of the lower limbs
21
Q
What is the Corticobulbar tracts?
A
Motor tracts for conscious movement of the muscles of the face
22
Q
What is housed in the genu of the Internal Capsule?
A
The Corticobulbar tracts
23
Q
What are the nuclei associated with the corticobulbar tracts?
A
*Oculomotor nucleus
*Abducens
*Trochlear
*Trigeminal
*Facial
24
Q
Why is a stroke or lesion the the internal capsule important?
A
Because the internal capsule houses many axon tracts
25
What is found in layer I of the cortex?
- Few nerve cell bodies
- Many dendritic and axonal processes in synaptic interaction
26
What is found in layer II of the cortex?
- Small neurons which establish intracortical connections
27
What is found in layer III of the cortex?
- Medium-sized neurons giving rise to association and commissural fibres
28
What is found in layer IV of the cortex?
Termination of afferent fibres from the thalamus
29
What is found in layer V of the cortex?
- The origin of projection fibres to extracortical targets, such as BG, thalamus, brainstem and spinal cord
- In the primary motor cortex of the frontal lobe, this layer contains corticospinal tract cell bodies
30
What is found in layer VI of the cortex?
Association and projection fibers
31
In what layer of the cortex is association and projection fibers found?
Layer VI
32
In what layer of the cortex are:
- Few nerve cell bodies
- Many dendritic and axonal processes in synaptic interaction
Layer I
33
In what layer of the cortex are:
- Small neurons which establish intracortical connections
Layer II
34
In what layer of the cortex are:
- Medium-sized neurons giving rise to association and commissural fibres
Layer III
35
In what layer of the cortex are:
- Termination of afferent fibres from the thalamus
Layer IV
36
In what layer of the cortex are:
- The origin of projection fibres to extracortical targets, such as BG, thalamus, brainstem and spinal cord
- In the primary motor cortex of the frontal lobe, this layer contains corticospinal tract cell bodies
Layer V
37
What is functionally located in the Frontal Lobe?
- Higher cognitive function
- Motor planning and execution
- Language
38
What is functionally located in the Parietal Lobe?
- Somatic sense of body image
- 3D localization of self and targets in space
- Language
39
What is functionally located in the Occipital lobe?
Vision
40
What is functionally located in the temporal lobe?
- Short-term memory
- Learning
- Auditory
41
Where is:
- Higher cognitive function
- Motor planning and execution
- Language
Frontal Lobe
42
Where is:
- Somatic sense of body image
- 3D localization of self and targets in space
- Language
Parietal Lobe
43
Where is:
- Vision
Occipital lobe
44
Where is:
- Short-term memory
- Learning
- Auditory
Temporal Lobe
45
What is stored in the Limbic system?
Emotional, social and sexual behavior
46
Where is:
Emotional, social and sexual behavior
Limbic system
47
What is information on functional localization mostly from?
- Stimulation and ablation studies
- Electrophysiological recording
- Observations of regional blood flow
- Post mortem studies of patients with known lesions
48
What is the Montreal surgery?
Stimulating the brain with electrical probes while patients were conscious to observe their responses. This led to the cortical homunculus
49
What led to homunculus?
The Montreal surgery where they stimulated brains of conscious people and observed responses
50
What led to Broca's area?
The post-mortem study of patient 'Tan' who could understand everything but could only speak the word Tan
51
What was discovered in patient Tan?
A lesion in the left inferior frontal lobe - the orbital triangular and opercular which makes up Broca's speech area
52
What area of the brain is Broca's speech area?
Left inferior frontal lobe - the orbital triangular and opercular
53
Where is Wernicke's area?
The posterior portion of the left temporal lobe
54
What happens if there is a lesion in Wernicke's area?
People cannot understand what is being said to them and their speech is often incoherent and makes no sense**
55
What is the function of the Primary Auditory Cortex?
Sound Localization
56
Where is the primary auditory cortex located?
Heschl's gyrus
57
What is housed in Heschl's gyrus?
The primary auditory cortex
58
Where is information carry from Heschl's gyrus?
Short association fibres carry information to neighbouring gyri like Wernicke's area and Broca's area
59
What is the function of Wernicke's sensory speech area?
Comprehension of sound
60
What will a lesion to Wernicke's sensory speech area cause?
Sensory and Receptive Aphasia
61
What is Sensory Aphasia?
Inability to understand spoken word
62
What is receptive aphasia?
When someone is able to speak well and use long sentences, but what they say may not make sense
63
What may cause sensory and receptive aphasia?
A lesion to Wernicke's sensory speech area
64
What is the function of Broca's Motor Speech Area?
Formulation of the motor movements for speech
65
What can a lesion to Broca's area cause?
Broca's aphasia, motor aphasia or expressive aphasia - can understand what they are hearing but can't reply
66
What is Broca's aphasia, motor aphasia, or expressive aphasia?
Issues with producing speech
67
What may cause issues with producing the motor movements for speech?
A lesion to Broca's area
68
What is the Arcuate Fasciculus?
A white matter tract that runs from Wernicke's to Broca's area
69
What is the Arcuate Fasciculus used for?
When a person is asked to repeat after another person
70
What can a lesion to the Arcuate Fasciculus cause?
Conduction aphasia, but they are good with spontaneous speech
71
What is conduction aphasia?
The inability to repeat words or phrases
72
What may cause conduction aphasia?
The inability to repeat words or phrases
73
What are the steps to verbally respond to a question?
1. Listen (primary auditory cortex)
2. Comprehend (Wernicke's area)
3. Send association fibres through the Arcuate Fasciculus
4. Broca's motor speech area to formulate speech
5. Activate UMN for speech muscles
74
What are the three operation system of the brain?
1. Sensory systems
2. Association systems
3. Motor systema
75
What do the Sensory systems do?
Create the internal representation of the outside world
76
What do association systems do?
Integration of diverse sensory information for planning purposeful action
77
What is the Topography of the Primary Sensory Cortex?
The Homonculus
78
What is the Homunculus essential for?
Recognition and localization of sensory stimuli
79
What is the each primary sensory area surround by?
A larger zone of association cortex that interpret that sensation
80
What is an association cortex?
An area that interprets the incoming signals and is appropriately connected to other parts of the cerebral cortex
81
What do Lesions to Association cortices cause?
- Agnosias
- Aphasias
- Apraxias
82
What are Agnosia's?
The inability to recognize common objects (parietal lobe)
83
What lobe are Agnosia's associated with?
The Parietal lobe
84
What are aphasias?
The inability to understand/vocalize speech
85
What are aphasia associated with?
Wernicke's or Broca's area
86
What are Apraxias?
The inability to execute purposeful movements (motor planning disorder)
87
What may a lesion in the Primary Sensory Cortex cause?
Tingling and numbness
88
What is the Posterior Parietal Cortex?
The association cortex for the Primary Sensory Cortex
89
What can a lesion in the Posterior Parietal Cortex cause?
Agnosia - won't be able to identify something by touch
Neglect - Won't understand that their own body is a part of themselves
90
What may cause Agnosia and Neglect?
A lesion to the Posterior Parietal Cortex
91
What may a lesion to the Primary Visual Cortex cause?
Visual Field Defects
92
What may a lesion to the Visual Association Cortex cause?
Visual Agnosia - Issues interpreting what is seen
93
What may cause visual agnosia?
A lesion to the Visual Association Cortex
94
What may a lesion to the Primary Auditory Cortex cause?
Inability for sound localization
95
What may cause the inability for sound localization?
A lesion to the primary auditory cortex
96
What may a lesion to Wernicke's sensory speech area cause?
Sensory and receptive aphasia - inability to comprehend
97
What can lesions to the Parietal, temporal and Occipital association cause?
Different agnosias
98
What can lesiona to the Limbic association cortex cause?
Schizophrenia and depressive illness
99
What may cause Schizophrenia and depressive illness?
Lesions to the Limbic Association Cortex
100
What do Lesions to the Prefrontal Association Cortex cause?
Personality and behavior disorders
101
What causes personality and behaviour disorders?
Lesions to the prefrontal cortex
102
What makes up the Primary Olfacotry area?
The uncus, parts of the insula and the frontal gyri
103
What are lesions to the parietal association cortex usually like?
They are often incomplete and the ability to feel an object may be present but there may be a defect in the ability to interpret this sensation
104
What is Tactile Agnosia?
The inability to interpret a touch sensation due to a lesion in the parietal association cortex
105
What is Astereognosis?
The loss of awareness of the spatial relation of parts of the contralateral side of the body (can't discriminate shape)
106
What is another name for Astereognosis?
Tactile amnesia
107
What is Cortical Neglect?
An extreme form of astereognosis in which the patient ignores/denies one side of the body and corresponding visual field
108
What is the ventral stream of the Visual association cortex for?
- Color
- Letters
- Faces
-Visual memories
109
What is the Dorsal Stream of the Visual Association Cortex for?
- 3D visual understanding of an object
- Motion of an object
110
What does a lesion to the Ventral stream cause?
Prosopagnosia
111
What causes Prospopagnosia?
A lesion to the ventral stream
112
What is Prosopagnosia?
Cannot recognize faces
113
Which visual association stream recognizes:
- Color
- Letters
- Faces
- Visual memories
Ventral Stream
114
Which Stream recognizes:
- 3D visual understanding of an object
- Motion of an object
Dorsal Stream
115
Which lobe is the Dorsal Stream apart of?
The occipital and parietal lobe
116
What does a lesion to the primary auditory cortex cause?
Wernicke's aphasia
117
What is Wernicke's aphasia?
When you can't understand the difference between someone's voice and other sounds
118
What is Amusia?
A right side lesion in the Primary Auditory cortex leading to inability to recognize previously 'familiar' voices and music
119
What causes Amusia?
A right side lesion in the primary auditory cortex
120
What is unique about the olfactory and gustatory association cortices?
They intermix
121
What is the function of the Olfactory and Gustatory cortices?
They allow us to smell and identify taste
122
Why do the Olfactory and Gustatory cortices send association fibers?
To get an emotional response to a smell or taste and to acquire memories associated with smell
123
What can a lesion to the olfactory and gustatory cortex cause?
Anosmia - loss of smell which leads to lack of taste
124
What causes Anosmia?
A lesion to the olfactory and gustatory association cortices
125
What is localized in the left hemisphere?
- Broca's motor speech area (frontal lobe)
- Wernicke's sensory speech area
126
What is the Premotor cortex responsible for?
Telling upper motor neurons when to fire
127
How do the Premotor cortex and the Supplementary Motor cortex work?
They receive feedback from basal ganglia, reticular formation, and the limbic system, which they integrate in order to tell the primary motor cortex when to fire
128
Where is sensory information in the motor system coming from?
- Understanding your surroundings - Posterior parietal Cortex
- Visual info - Primary Visual Cortex
129
What are the three main steps in motor movements?
1. Identification of body in space - posterior parietal cortex
2. Formulation of plan - Premotor cortex
3. Execution of movement - Primary motor cortex
130
What are the descending motor pathways?
- Corticospinal
- Corticobulbar
- Corticoreticular
- Reticulospinal
- Vestibulospinal
- Rubrospinal
131
What are the two conscious descending motor pathways?
Corticospinal and corticobulbar
132
What two things can an UMN do to a LMN?
It can excite or inhibit the LMN
133
What does a lesion to the UMN cause?
Disinhibition of the LMN causing spastic paralysis
134
What causes spastic paralysis?
A lesion to the UMN
135
What does a lesion to the LMN cause?
Flaccid paralysis so the LMN won't contract
136
What is the Hierarchy of the Descending Motor Pathways?
1. Corticobulbar and Corticospinal (pyramidal tracts)
2. Corticoreticular, reticulospinal, vestibulospinal, rubrospinal (extrapyramidal tracts)
137
Describe the Corticospinal and Corticobulbar tract?
The allow for voluntary control of LMNs but they receive input from the basal ganglia and cerebellum o ensure smooth, coordinated, purposeful movement
138
What are the Corticospinal and Corticobulbar tract modulated by?
The basal ganglia and cerebellum
139
What do the basal ganglia and cerebellum do for the Corticospinal and Corticobulbar tracts?
Ensure smooth, coordinated and purposeful movement
140
What can a basal ganglia lesion causes?
Parkinson's disease
Huntington's Chorea
141
What does a Cerebellar lesion cause?
Ipsilateral ataxia
142
Why are the extrapyramidal tracts important?
Because they work behind the scene to allow conscious movements to occur in the right way so that we don't need to think about multiple movements
143
What are the four extrapyramidal tracts?
- Corticoreticulospinal tract
- Vestibulospinal tract
- Rubrospinal tract
- Tectospinal tract
144
What does the Corticoreticulospinal tract do?
Excitatory to leg extensors and arm flexors
145
What does the Vestibulospinal tract do?
Excitatory to arm and leg extensors and inhibitory to arm and leg flexors
146
What does the Rubrospinal tract do?
Inhibitory to arm extensors and excitatory to arm flexors. No effect on leg muscles
147
What does the Tectospinal tract do?
Influences leg muscles
148
Which descending motor pathway is excitatory to leg extensors and arm flexors?
The Corticoreticulospinal tract
149
Which descending motor pathway is excitatory to arm and leg extensors and inhibitory to arm and leg flexors?
The vestibulospinal tract
150
What descending motor pathway is inhibitory to arm extensors and excitatory to arm flexors with no effect on leg muscles?
The Rubrospinal tract
151
What descending motor pathway influences the neck muscles?
The tectospinal tract
152
How does the tectospinal tract influence the neck muscles?
Turns the head with you see something in the visual field or when someone whispers in the ear etc
153
What are the two types of posturing?
Decorticate posturing
Decerebrate posturing
154
Where in the brain is a lesion that causes Decorticate Posturing?
The lesion is below the cerebral cortex and at the very top of the midbrain
155
What are the characteristics of the tracts in Decorticate Posturing?
The extrapyramidal tracts are all functional
- The rubrospinal tract flexes the upper body
- The corticoreticular tract flexes upper body and extends lower body
- The vestibulospinal tract is excitatory to arm/leg extensors and arm extensors are overruled by corticospinal and rubrospinal tracts
156
What are the characteristics of the limbs in Decorticate Posturing?
Arms flexed and legs extended
157
What are the characteristics of the limbs in deceberate posturing?
Arms and legs extended
158
What are the characteristics of the pathways in Decerebrate Posturing?
- CST and Rubrospinal tract are not active
- Corticoreticulospinal tract want to flex upper body (overruled by VST) and extend lower body
-Vestibulospinal tract is excitatory to arm and leg extensors and inhibitory to arm and leg flexors with extends upper body
159
As a brainstem lesion gets lower what happens to the posturing?
Can change a decorticate to a decebreate Posturing
