8 - Cerebral Cortex (Exam 2) Flashcards
What is a sulcus?
A “valley” in the cerebral cortex
What is a gyrus?
A “peak” in the cerebral cortex
What are the 2 major purposes of sulci and gyri?
- Divide
2. Increase surface area
In what way are cortical layers organized based on cell type?
Horizontal rows
In what way are cortical layers organized based on function?
Vertical columns
Which forms most of the human cortex, the neocortex or the allocortex?
Neocortex
What is the allocortex comprised of?
The paleocortex and archicortex
What are the 6 layers of the neocortex?
- I - Molecular layer
- II - External granular layer
- III - External pyramidal layer
- IV - Internal granular layer
- V - Internal pyramidal layer (Ganglionic layer)
- VI - Multiform layer
Where are pyramidal neurons found?
Layer III
Layer V
In what types of functions are pyramidal neurons mainly involved?
Efferent functions
Where are granular neurons found?
Layer II
Layer IV
In what types of functions are granular neurons mainly involved?
Afferent functions
What is another name for granular neurons?
Stellate neurons
What are the 2 types of cortical classification?
- Homotypical cortex
2. Heterotypical cortex
Which type of cortical classification makes up the majority of human cortex?
Homotypical cortex
What constitutes a classification of heterotypical cortex?
Any area of cortex that doesn’t have six layers
What are the 2 types of heterotypical cortex?
- Granular type
2. Agranular type
What is meant by the granular type of heterotypical cortex and where is it typically found?
Granular layers (II and IV) well developed Auditory cortex, postcentral gyrus, parts of visual cortex
What is meant by the agranular type of heterotypical cortex and where is it typically found?
Granular layers (II and IV) poorly developed Frontal lobe
What is the role of association fibers?
Interconnect areas of cortex within the same hemisphere
Therefore no decussation
What 2 areas does the superior longitudinal fasciculus connect?
Broca’s area and Wernicke’s area
What is another name for the superior longitudinal fasciculus?
Arcuate fasciculus
What areas does the inferior occipitofrontal fasciculus connect?
Frontal lobe
Temporal lobe
Occipital lobe
What is another name for the inferior occipitofrontal fasciculus?
Uncinate fasciculus
What areas does the superior occipitofrontal fasciculus connect?
Frontal lobe
Parietal lobe
Occipital lobe
What is the purpose of the cingulum?
Connects areas of the limbic cortex
What is the role of commissural fibers?
Interconnects areas of cortex across both hemispheres
Decussation usually occurs at corpus callosum
What is the largest cortical commissure?
Corpus callosum
What does the anterior commissure connect?
Anterior temporal lobes and olfactory bulbs
What does the posterior commissure connect?
Both pretectal nuclei
What compact bundle do the corona radiata converge into and form?
Internal capsule
What is the bend of the internal capsule called?
genu
How do injuries to primary cortical areas differ from injuries to association cortical areas
Injuries to a primary cortex (ex: primary visual area) result in clear cut, defined deficits
Injuries to an association cortex results in less specific deficits like personality changes
Where is the primary motor cortex located?
The frontal lobe
Specifically on the precentral gyrus
What would a lesion of the PMC present as?
Weakness and/or paralysis
What would a lesion of motor association areas present as?
Apraxia
Deficit in learned skill without paresis
(Unable to brush hair)
Where is the primary sensory cortex located?
The parietal lobe
Specifically on the postcentral gyrus
Projection fibers come from all parts of the cortex into what?
Corona radiata
The left primary motor cortex sends motor output to which side of the body?
Right side
The left primary sensory cortex receives sensory input from which side of the body?
Right side
What is meant by cortical plasticity?
Cortical representation of the body can change
Based on change in sensory input from particular part or area of the body
What would a lesion of the PSC present as?
Deficits in awareness and localization of stimuli
What would a lesion of sensory association areas present as?
Tactile agnosia (inability to recognize an object by touch) or Astereognosis (inability to recognize object placed in hand)
Where is the primary visual cortex located?
The occipital lobe
Specifically above and below the calcarine sulcus
The left primary visual cortex receives information from which side of the visual field?
Right visual field
The superior (above calcarine sulcus) primary visual cortex receives information for which part of the visual field?
Inferior visual field
What occurs in the visual association areas?
Higher order processing that gives meaning and interpretation to what we see
What would a lesion of the left primary visual cortex present as?
Homonymous hemianopsia of the right visual field
What would a lesion of visual association areas present as?
Visual agnosia (Inability to recognize familiar objects) Pursuit or saccadic deficits
Where is the primary auditory cortex located?
Temporal lobe
Specifically deep within lateral sulcus on surface of superior temporal gyrus
What would a lesion of the primary auditory cortex present as?
Decreased perception of sound primarily in contralateral ear
What would a lesion of auditory association areas present as?
Acoustic verbal agnosia (no ability to interpret words though hearing is intact)
What is the frontal association area responsible for?
Planning, adaptation to social norms
What is the parietal association area responsible for?
Attention and awareness
What is the temporal association area responsible for?
Recognition of stimuli and patterns
What kind of lesion would result in left spatial inattention?
Lesion of the right parietal lobe
What is prosopagnosia?
Inability to recognize faces
Where is Broca’s area located and what is its purpose?
Inferior frontal gyrus of frontal lobe
Production of language
Where is Wernicke’s area located and what is its purpose?
Superior temporal gyrus of parietal/temporal lobe
Comprehension of language
What does the arcuate fasciculus join?
Broca’s area and Wernicke’s area
How is aphasia different from aysarthria?
Aphasia is the inability to communicate
Dysarthria is disrupted production due to pharynx, tongue, etc.
How does Broca aphasia differ from Wernicke aphasia
With Broca aphasia, the patient will understand what you say but will be unable to respond effectively (gets frustrated)
With Wernicke aphasia, the patient will not understand what you are saying (is unaware)
Does the arcuate fasciculus have a smaller or larger role in the modern model compared to the classical model?
Smaller role
Not all disorders fit into Broca or Wernicke classifications
