L46,47 - Higher Cortical Functions I&II Flashcards
1
Q
Define the cerebral hemispheres (lobes)?
A
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
2
Q
Gross structural organization of the cerebral cortex?
A
Laminar organization – 6 layers Composed of glial cells, neurons, each layer has diff. input and output
–I.MolecularorPlexiformlayer
–II.External(Outer)granularlayer
–III.Externalpyramidallayer
–IV.Internal(Inner)granularlayer
–V.Internalpyramidallayer
–VI.Multiform(Polymorphiclayer)
3
Q
Gross functional organization of the cerebral cortex?
A
Columnar function organization:
“Column” of cells with similar response properties
» Overlapping / nearly identical receptive field
E.g. area 17: process Right eye and Left eye info.
4
Q
Input of Layer I of cortex?
A
Brainstem modulatory systems Other cortical areas
5
Q
Input and output of Layer II of cortex?
A
Brainstem modulatory systems Other cortical areas
Other cortical areas
6
Q
Input and output of Layer III of cortex?
A
Brainstem modulatory systems
Other cortical areas Opposite hemisphere
7
Q
Input of Layer IV of cortex?
A
Brainstem modulatory systems
Thalamus
8
Q
Input and output of Layer V of cortex?
A
Brainstem modulatory systems Other cortical areas
Subcortical structures, e.g.: Striatum Superior colliculus
9
Q
Input and output of Layer VI of cortex?
A
Brainstem modulatory systems
Thalamus
10
Q
Thalamus input and output at which layer of the cortex?
A
Input at layer IV
Output at layer VI
11
Q
Which layer of the cortex outputs to subcortical structures?
A
Layer V
Subcortical structures, e.g.: Striatum Superior colliculus
12
Q
2 main types of neurons in the cortical layers?
A
1) Pyramidal neurons: Spiny excitatory (glutamatergic) neurons (majority)
2) Non-spiny inhibitory (GABAergic) interneurons
13
Q
Compare the neurotransmitter, morphology and abundance of Pyramidal neurons vs interneurons in the cortical layers?
A
Pyramidal:
- Glutamate
- Homogeneousmorphology
- 70‐80%
Interneuron:
- GABA
- Heterogeneous
~20‐30%
14
Q
Input and output of lateral geniculate nucleus?
A
Input = retinal ganglion cells
Output = Occipital lobe
15
Q
Input and output of Dorsomedial nucleus of thalamus?
A
Input: Medulla, olfactory cortex
Output: Orbitofrontal cortex, amygdala
16
Q
Input and output of VPL and VPM of thalamus?
A
Spinothalamic/ DCML input + trigeminothalamic (VPM only)
Postcentral gyrus/ primary somatosensory cortex output + Temporal lobe
17
Q
Input and output of anterior nucleus of thalamus?
A
Hippocampus, Mammilary body input
Cingulate cortex output
18
Q
Input and output of medial geniculate nucleus in thalamus?
A
Cochlear nucleus/ central auditory pathway input
Primary auditory cortex output
19
Q
Output of Pulvinar (anterior, medial, lateral, inferior) of thalamus?
A
Occipital lobe
20
Q
List the higher cortical areas in the frontal lobe.
A
Premotor, SMA
Primary motor
Speech motor - Broca
Prefrontal
21
Q
List the higher cortical areas in the Parietal lobe.
A
Primarysomatosensorycortex,somatosensoryassociation area
22
Q
List the higher cortical areas in the Occipital lobe.
A
Primary visual
Visual association
23
Q
List the higher cortical areas in the temporal lobe.
A
Primary auditory
Wernicke’s area
Auditoryassociationcortex
Memory
24
Q
Functions of the frontal lobe. (think about the higher centers there)
A
- Emotion,personality,socialcontrol,speaking
- Executivefunction:planning,decision‐making,makingjudgments,attention
- Controlofmovement
25
Functions of the Parietal lobe. (think about the higher centers there)
* somatosensory function (e.g. sense of touch)
* Interpretation of shape and textures
* Understanding speech and formulating words
26
Functions of the Occipital lobe. (think about the higher centers there)
* Processes visual information
| * Correlation of visual images with previous visual experience
27
Functions of the temporal lobe. (think about the higher centers there)
* Mostly concerned with speech and hearing
| * Storage of auditory experience
28
Define the functional categories of cerebral cortex.
* Four functional categories:
| * Primary motor, primary sensory, unimodal association cortex (secondary), multimodal association cortex (tertiary)
29
Purpose of the Primary Sensory functional category of the cerebral cortex?
receives thalamocortical fibers from diencephalic relay nuclei related to their functional modality:
Somatosensory Visual Auditory
30
Function of the Unimodal association cortex?
Adjacent to primary cortex
Devoted to higher level of information processing:
primary sensory > motor and somatosensory association area > higher‐order somatosenory association area and premotor cortex
31
Function of Multimodal association areas?
receive information from several different sensory modalities:
(1) the production of a unified percept (2) the representation of the percept in memory
32
Which cognitive functions are executed at the multimodal association areas?
–Use of language
–Future planning
–Imagine and create
–Appreciation of space, etc.
33
List all the motor areas in the cerebral cortex?
* Primary motor cortex (Area 4)
* Premotor cortex (Area 6)
* Frontal eye field (Area 8)
* Broca’sarea (Area 44, 45)
34
Location, function, organization of the Primary motor cortex?
* Located in the precentral gyrus
* Allows conscious control of precise, skilled, voluntary movements (on the opposite side of the body) via direct connection with spinal cord
* represented in an orderly manner in the cortex: Homunculi
35
Describe the mapping of the primary motor cortex?
Body is mapped upside down
Homunculi: body regions with the greatest number of motor innervations (e.g. hands, face, tongue) are represented by largest areas of motor cortex
disproportionate representation of the body on the primary motor cortex
36
Motor function planned in the primary motor area can be executed without additional sensory input. T or F?
False
Motor function Need continuous stream of tactile, visual, proprioceptive information for accuracy, proper sequence
37
List all 6 sensory areas in cerebral cortex?
* Primary somatosensory cortex (Area 1,2,3)
* Visual cortex (Area 17)
* Auditory cortex (Area 41,42)
* Vestibular cortex
* Gustatory cortex (Area 43)
* Olfactory cortex
38
Location, Input, Mapping and function of primary somatosensory cortex?
* Located in the postcentral gyrus
* Receives information from the skin and skeletal muscles
* Homunculi mapping
* Exhibits spatial discrimination
39
Tract the visual pathway from retina to cortex?
Photoreceptor cells (rod, cone) > bipolar cells > ganglion cells
> optic nerve > optic chiasm > optic tract
> lateral geniculate nucleus/body (6 layers of neurons) of the thalamus
> optic radiation to visual cortex:
Right cortex process right temporal + left nasal field, vice versa
40
Which side of the thalamus relays visual information from which side of the visual field (nasal/ temporal)?
- Temporal hemiretina > ipsilateral lateral geniculate nucleus
- Nasal hemiretina > crosses over at optic chiasm > contralateral lateral geniculate nucleus
41
Tract the pathway for superior visual field quadrant processing? (from retina to cortex)
Superior VF > Inferior retinal field quadrant > Lateral half of LGN
> Temporal** optic radiation > Geniculocalcarine tract > Inferior Calcarine bank in visual cortex
42
Tract the pathway for inferior visual field quadrant processing? (from retina to cortex)
Inferior VF > Superior retinal field quadrant > Medial half of LGN
> Parietal** optic radiation
>Geniculocalcarine tract
> Superior calcarine bank in visual cortex
43
Organization of primary visual cortex?
Organized in Orientation columns and Ocular dominance columns + blobs (vertical) for color
44
After optic radiation relays visual signal to primary visual cortex, what are the next higher centers?
1. Dorsal stream (magnocellular pathway) Projects to parietal association cortex
2. Ventral stream (parvocellular pathway) Projects to temporal association cortex
Both Eventually converge onto frontal association cortex
45
Compare the function of the parvocellular and magnocellar pathways for visual processing?
1. Dorsal stream (magnocellular pathway): Processes spatial information: position, motion, speed
2. Ventral stream (parvocellular pathway): Processes information about form: color, shape, texture
46
Give the lesion site + one example of condition causing: Bitemporal hemianopia (lose lateral visual field)
Optic chiasma lesion
i.e. Pituitary adenoma
47
Give the lesion site + one example of condition causing: Monocular amaurosis (one eye lose all vision)
Optic nerve lesion
i.e. optic neuritis
48
Give the lesion site + one example of condition causing: Homonymous hemianopia (no ipsilateral temporal + no contralteral nasal field)
Optic tract lesion
i.e. Cranio- pharyngioma
49
Give the lesion site + one example of condition causing: Homonymous upper quadrantic hemianopia. (loss of upper quadrant field of the same side in both eyes)
Temporal optic radiation lesion
posttemporal lobectomy
50
Give the lesion site + one example of condition causing: lower quadrantic hemianopia (loss of lower quadrant field of same side in both eyes)
Parietal optic radiation lesion
| e.g. parietal glioma
51
Give the lesion site + one example of condition causing: Dense hemianopia with macular sparing (Half of field loss on same side in both eyes, with normal macula spot)
Visual cortical lesion (e.g. occipital lobe infarct)
Central LGN still intact > Macular sparing > 1 of 2 bilateral projections to primary visual cortex still functional
52
Unilateral lesion in the auditory pathway can cause bilateral hearing loss. T or F?
False
Cochlear nucleus on each side projects fibers to ipsilateral (superior olivary complex) and contralateral tracts (lateral lemniscus)
Double decussation + bilateral processing means unilateral lesion unlikely to affect hearing
53
How is auditory info processed in the cerebral cortex? Brainstem centre processing?
All fibers from cochlear nucleus to primary auditory cortex maintain the tonotopic information pattern
Spatial mapping + Accurate localization of sound processed at cortex
Medial Geniculate body = upstream projection + downstream modulation
Inferior colliculus = Amplitude + frequency modulation, Reflex coordination (head movement + startle reflex), Downstream efferent modulation
Superior olivary complex = Gross localization of sound
Cochlear nucleus = frequency + temporal processing
Cochlear, basillar membrane = frequency + tonotropic map
54
Tract the gustatory pathway from taste buds to cortex?
Taste buds (CN VII, IX, X (epiglottis))
>> geniculate, petrosal, nodose ganglia
>> solitary tract + solitary nucleus***
>> central tegmental tract
>> VPM of thalamus
>> Gustatory cortex (area 43)
55
Brief outline of brain areas involved in forming vestibular cortex?
Balance needs many snesory integration:
Somatosensory cortex
Posterior insula
Premotor cortex (frontal eye field)
Parietal cortex
56
List some centers in the olfactory cortex?
- Piriform cortex
- Lateral entorhinal cortex
- Olfactory tubercule
- Anterior olfactory nucleus
- Anterior cortical amygdaloid nucleus
57
List the 4 association areas?
Parietal, temporal, Frontal, Limbic association cortices
58
Function of parietal and temporal association cortex?
* Parietal association cortex: sensory guidance of motor behaviour and spatial awareness.
* Temporal association cortex: recognition of sensory stimuli + storage of semantic (factual) knowledge
59
Function of frontal and limbic association cortex?
•Frontal (prefrontal) association cortex : organizing behaviour + working memory. •Limbic association cortex: (Located in the anterior ventral portion of the temporal lobe) emotion and episodic (autobiographical) memory
60
List 4 functions of Prefrontal cortex?
* Higher cognitive function, planning
* Personality expression
* Decision making, working memory
* Social behavior
61
Input and output of prefrontal cortex? Can it evoke movement?
Input : Projection zone of the mediodorsal nucleus of the thalamus
electrical stimulation does not evoke movements
Highly interconnected with other cortical, subcortical area and brain stem
62
Consequence of prefrontal cortex dysfunction?
psychiatry disorders, e.g. depression, schizophrenia
drastic and permanent personality changed
Lack of ability to plan ahead
63
Name of procedure done to limit interhemispheric spread of epileptic activity?
cut Corpus callosum
64
Compare the functions of Wernicke's and Broca's areas? Left or right brain?
Wernicke's = comprehension of written and spoken language and formation of coherent speech
Broca's = motor programs of speech and writing >> primary motor cortex
Normally located in the left hemisphere (if right-handed)
65
Symptoms and area of brain affected in expressive aphasia?
Understand language perfectly and may be able to write perfectly
Difficulty speaking spontaneously
>> Broca affected
66
Symptoms and area of brain affected in receptive aphasia?
unable to name objects
unable to understand the meaning of words
articulate speech readily, but usually nonsensically
>> Wernicke affected
67
Symptoms and area of brain affected in global aphasia?
almost total reduction of all aspects of spoken and written language
>> larger lesions in central region around lateral sulcus; large left middle cerebral artery injuries
68
Symptoms and area of brain affected in Conductive aphasia?
comprehension is normal and expression is fluent
Difficulty translating what's said into appropriate reply
>> interruption of the connections (arcuate fasciculus) linking the Brocaand Wernicke areas
69
Which association cortex is most highly lateralized in the brain?
Parietal association cortex
70
Brain area affected in Contralateral Neglect syndrome i.e. on the left side?
Damage to right parietal association cortex (non‐dominant)
= defect in attention, spatial surrounding, self‐image on the left side
71
List 4 cortical dysfunctions?
Aphasia
Apraxia
Agnosia
Ataxia
72
Define apraxia and brain areas affected?
Difficulty with the motor planning to perform tasks / movements >> Cannot internalize, duplicate the spatial relationships
Parietal association cortex;
Premotor cortex; or
Supplementary motor cortex
73
Define agnosia and list 3 subtypes?
higher level disorders of sensory perception even though afferent sensory pathways function normally
Tactile agnosia: cannot recognize objects through touch
Prosopagnosia: cannot recognize familiar faces / learn new faces
Visual agnosia: appreciative or associative
74
Clinical presentation of visual appreciative agnosia? (able to identify object? Normal object perception? Draw copy?)
- Cannot draw copy of image
- Can verbally identify object
- Cannot see object parts as a unified whole
- Cannot construct senosry representations of visual stimuli
75
Clinical presentation of visual associative agnosia? (able to identify object? Normal object perception? Draw copy?)
- Can copy image
- Cannot name objects/ interpret/ understand/ assign meaning
- Normal sensory representation but faulty association
>> Posterior multimodal association cortex lesion
76
Presentation and brain area affected in optic ataxia?
difficulty with visually guided grasping and reaching
damage to the dorsomedial parietal cortex
77
Define dementia, area of brain affected and related impairments? How to assess dementia?
Clinical syndrome of impaired cognitive function in multiple domains but with preserved consciousness
global dysfunction in cerebral cortex
Deterioration of memory, intellect, concentration, comprehension, specific cortical functions
Mini‐Mental Sate Examination (MMSE)
78
Most common form of dementia? Related genetic factors?
Alzheimer’s Disease
Mutation of amyloid precursor protein (APP), presenilins1 (PSEN1) and presenilin2 (PSEN2)
79
Pathogenesis of Alzheimer's?
1. Extracellular deposition of amyloid plaques***, composed of beta‐amyloid (Aβ)
2. Intracellular neurofibrillary tangles (NFT)***, composed of aggregates of highly phosphorylated microtubule binding protein, Tau***
3. Significant decrease in acetylcholine transferase and loss of cholinergic neurons
>> Memory loss, deficits of cognitive function, mood disorders
80
Sequence of brain areas affected in progression of Alzheimer's
Medial temporal lobe
> Lateral temporal, parietal lobes
> Frontal lobe
> Occipital lobe
81
How does functional imaging of cognition work?
Cognition = change in energy metabolism of neurons, synaptic activity and strength
i.e. increase cerebral blood flow and volume, increase glucose uptake ... etc
82
Principal of PET scans?
detects pairs of gamma rays emitted indirectly by a positron emitting radionuclide (tracer e.g. oxygen-15)
measured the flow of blood to different parts of the brain
83
Principal of fMRI?
detecting changes associated with blood flow.
Uses the blood‐oxygen‐level dependent (BOLD) contrast
(Better resolution than PET scan)
84
Principal of EEG?
electrical potential difference from the summation of postsynaptic potentials from pyramidal neurons in the cortex
measured by many electrodes on the scalp
85
What in EEG used to dx?
epilepsy, coma and brain death
Monitor sleep
86
List the 4 EEG patterns and the cognitive states related?
Alpha = awake, relaxed state of wakefulness, eyes closed
Beta = awake, alert, with visual stimuli
Theta = Concentrating of emotional stress in adults, common in brain disorders, common in children
Delta = deep sleep, indicate brain damage in awake adults
87
Principal of Magnetoencephalography MEG?
Electromagnetic fields are generated by the net effect of current flow in neurons
•The effect of multiple neurons excited together in a specific area generates measureable magnetic field
88
Define neuroplasticity and its function?
Remodeling of the CNS/ Re‐organization of synaptic networks to cause change in behavior/sensation
Function:
Learning and memory
Phantom limb sensation (i.e. after amputation)
Cortical remapping of referred sensation (i.e. after stroke)
