Cerebral Cortex B&B Flashcards
space between frontal and parietal lobes is called:
space between temporal and frontal/parietal lobes is called:
space between frontal and parietal lobes is called: central sulcus
space between temporal and frontal/parietal lobes is called: sylvian fissure
brain ridges are called:
brain folds are called:
brain ridges are called: gyrus/gyri
brain folds are called: sulcus/sulci
what is contained in the precentral gyrus?
motor cortex - organized by homunculus
in which lobe is Broca’s area found?
frontal lobe left hemisphere
damage —> expressive aphasia (“broken” speech)
according to a homunculus, which areas of the body will be most affected by a middle cerebral artery (MCA) stroke vs anterior cerebral artery (ACA) stroke?
MCA: upper limb, face
ACA: lower limbs (remember the legs “hang down” on the sides of the lobes)
the frontal eye fields are found in which Brodmann Area? to which side will the eyes deviate if there is a lesion?
Brodmann Area 8 (frontal lobe)
frontal eye fields perform conjugate eye movements to opposite side (saccadic/back-forth and complex/tracking object)
destructive lesion —> deviation to side of lesion
speech pathologies caused by lesion to Broca’s area vs Wernicke’s area
Broca’s area (L frontal lobe) —> expressive aphasia (broken speech)
Wernicke’s area (temporal lobe) —> fluent aphasia (meaningless speech)
damage to both on L side (via stroke) —> global aphasia (mute), usually accompanied by extensive CNS damage (R hemiparesis, R visual loss)
patients showing signs of disinhibition, lack of concentration, disorientation, poor judgment, and reemergence of primitive reflexes most likely have brain damage to where?
prefrontal cortex - anterior 2/3 of frontal lobe
(ex - Phineas Gage)
what occurs from damage to the right parietal lobe?
contralateral (left) spatial neglect and agnosia - normal vision/somatic sensation but can’t perceive objects in the part of space (even body parts), failure to respond to stimuli
right-sided spatial neglect is rare due to redundant processing of right side by left/right brain
where is Baum’s loop found, and what occurs with damage to this structure?
part of visual pathway in parietal lobe
damage —> quadratic anopia with “pie in the floor” loss of vision
quadratic anopia with “pie in the floor” loss of vision is caused by damage to which brain structure?
Baum’s loop in parietal lobes - part of visual pathway
loss of 1 lower visual quadrant in both eyes
what is the function of Meyer’s Loop, where is it found, and what occurs from damage?
Meyer’s Loop - part of visual pathway, found in temporal lobes
damage —> quadratic anopia with ”pie in the sky” loss of vision (1 upper quadrant on each side lost)
quadratic anopia with “pie in the sky” loss of vision is caused by damage to which brain structure?
Meyer’s Loop in temporal lobes
what is the cause of “pie in the sky” vs “pie in the floor” quadratic anopia?
“pie in the sky” = damage to Meyer’s Loop in temporal lobes
“pie in the floor” = damage to Baum’s loop in parietal lobes
damage to the bilateral amygdala (temporal lobes) would cause _____ syndrome… how does this present?
Kluver-Bucy Syndrome: hyperphagia (weight gain), hyperorality (putting things in mouth), hypersexuality, visual agnosia (inability to recognize visually presented objects)
can be a rare complication of HSV1 encephalitis
Kluver-Bucy Syndrome
damage to bilateral amygdala
hyperphagia (weight gain), hyperorality (putting things in mouth), hypersexuality, visual agnosia (inability to recognize visually presented objects)
can be a rare complication of HSV1 encephalitis
Pt with HSV1 encephalitis is now showing signs of weight gain, hyperorality, and inappropriate sexual behavior - what should you be concerned about?
Kluver-Bucy Syndrome: bilateral damage to amygdala
—> hyperphagia (weight gain), hyperorality (putting things in mouth), hypersexuality, visual agnosia (inability to recognize visually presented objects)
can be a rare complication of HSV1 encephalitis
strokes to which cerebral artery can cause homonymous hemianopsia?
posterior cerebral artery (PCA) supplies temporal lobe
damage —> homonymous hemianopsia (left PCA stroke = right visual loss, right PCA stroke = left visual loss)
however, macula is often spared due to dual blood supply of MCA and PCA!
primary cortex vs unimodal association cortex vs heteromodal association cortex vs limbic cortex
primary cortex: receiving 1 modality from sensory pathways, or controlling LMN
unimodal association cortex: integration of 1 modality
heteromodal association cortex: association with multiple modalities, perform highest order functions
limbic cortex: associated bidirectionally with memory and emotional subcortical systems
what are the behavioral changes that occur with prefrontal cortex dysfunction?
IRS AOM
Initiative - loss of motivation
Restraint - loss of inhibition
Social - inappropriate laughter, loss of empathy
Anticipate - difficulty predicting consequences, risk-taking behavior
Order - decreased capacity to correctly perform sequencing tasks and cognitive operations
Monitor - inability to adjust behavior for change in situation
describe perseveration and impersistence which might be seen with prefrontal cortex dysfunction
perseveration: patient can’t follow a changing pattern (asked to repeat a pattern an examiner drew and get’s stuck)
impersistence: unable to sustain certain movements (stick tongue out, hold arms up)
what is the function of the frontal eye fields, and what occurs from a lesion?
frontal eye fields: push gaze contralaterally
lesions —> gaze deviation TOWARD injury
seizures can also cause gaze deviation toward seizure focus
lesions to Broca’s area are associated with infarcts of _________ artery
superior division of the middle cerebral artery
agraphesthesia and astereognosis are associated with lesions to which region of the brain? how do these present?
primary somatosensory cortex lesions
agraphesthesia: can’t recognize shape traced on skin due to disorientation of skin’s sensation across space
astereognosis: inability to recognize objects by feel
what is the major function of the right parietal association cortex?
selective attention - largely handled by the right (non-dominant) hemisphere
what is the result of lesion to the dominant vs non-dominant parietal association cortex?
right (non-dominant) - controls selective attention; lesion = inability to concentrate on one aspect of the environment
left (dominant) lesion = contralateral hemineglect (sensory or motor)
What is the cause of presentation (4) of Gerstmann syndrome?
damage to inferior parietal lobe on dominant (usually left) hemisphere – region of angular gyrus —>
- acalculia: impaired simple arithmetic
- agraphia: impaired writing
- finger anomia: inability to name individual fingers such as index and thumb
- right-left confusion
what would be the consequence of damage to the inferior parietal lobe on the dominant hemisphere, in the area of the angular gyrus? (4)
Gerstmann’s Syndrome:
1. acalculia: impaired simple arithmetic
2. agraphia: impaired writing
3. finger anomia: inability to name individual fingers such as index and thumb
4. right-left confusion
if a patient presents with acalculia, agraphia, finger anomia, and/or right-left confusion, which region of the cerebrum is damaged?
Gerstmann’s Syndrome: damage to inferior parietal lobe on dominant (usually left) hemisphere – region of angular gyrus —>
- acalculia: impaired simple arithmetic
- agraphia: impaired writing
- finger anomia: inability to name individual fingers such as index and thumb
- right-left confusion
In which temporal lobe (R or L) is Wernicke’s area found?
dominant hemisphere – usually left
lesion —> “receptive” aphasia, impaired comprehension
How do patients with Wernicke’s aphasia present? An infarct in which artery would most likely cause this presentation?
“receptive” aphasia – impaired comprehension, and paraphasic errors (inappropriate substitution of words)
Associated with infarcts of the inferior division of the middle cerebral artery
What is the result of a unilateral lesion to the primary auditory cortex?
difficulty localizing auditory inputs - will NOT cause hearing loss
Apraxia
inability to perform skilled movement that is not caused by sensory loss, elemental motor disorders, or severe impairments in cognition or attention
Can be caused by lesions to the dominant (usually left) hemisphere, including the fronto-temporo-parietal network
Ideomotor apraxia vs limb–kinetic apraxia
ideomotor apraxia: loss of the ability to make a skilled gesture to verbal command or imitation, associated with Huntington’s
limb-kinetic apraxia: loss of the ability to make fine motor movements, associated with Parkinson’s
Agnosia usually results from damage to which region of the cortex?
agnosia = failure of recognition, despite and intact sensory processing
usually due to damage of the “what” pathway – inferior occipitotemporal cortex
apperceptive agnosia versus associative agnosia versus prosopagnosia
Apperceptive agnosia: impaired integration of visual information, preventing generation of an internal representation of the object
• Patients can’t copy a stimulus
Associative agnosia: intact internal representation of an
object but an inability to connect it to stored information identifying it
• Patients can copy a stimulus, but
can’t identify it
Prosopagnosia: inability to recognize faces
Balint’s syndrome - cause and presentation (3)
caused by bilateral lesions of the “where” pathway (dorsolateral parieto-occipital association cortex); Associated with MCA-PCA watershed infarcts and posterior cortical atrophy
- Simultagnosia: inability to perceive more than one object at a time
- Optic ataxia: inability to coordinate movement of the hand based on visual cues
- Ocular apraxia: difficulty making saccadic eye movements to a target
Lesions of the dorsolateral parieto-occipital association cortex =
Balint syndrome: Associated with MCA-PCA watershed infarcts and posterior cortical atrophy
- Simultagnosia: inability to perceive more than one object at a time
- Optic ataxia: inability to coordinate movement of the hand based on visual cues
- Ocular apraxia: difficulty making saccadic eye movements to a target
lesions of inferior occipitotemporal cortex =
agnosia = failure of recognition, despite and intact sensory processing
usually due to damage of the “what” pathway – inferior occipitotemporal cortex
what are the clinical findings of lesions to the following regions of the parietal cortex?
a. Primary somatosensory cortex.
b. right parietal association cortex
c. Dominant parietal lobe.
Primary somatosensory cortex: contralateral cortical sensory loss
Right parietal association cortex: left neglect
Dominant parietal lobule (region of angular gyrus): Gerstmann’s syndrome (acalculia + agraphia + finger anomia + right-left confusion)
in which lobe of the brain is the micturition inhibitory area found?
Frontal lobe; lesion —> incontinence
Which region specifically is the language area found in the brain?
Perisylvian language area - localized to the region surrounding the sylvian fissure
Lateralized to the dominant side, usually left side
contrast the following types of aphasias:
a. Global aphasia.
b. Broca’s aphasia
c. Wernicke’s aphasia.
d. conduction aphasia
e. Transcortical aphasia
a. Global aphasia: damage to perisylvian region, all aspects of language impaired
b. Broca’s aphasia: receptive language and reading comprehension intact, all other aspects of language impaired
c. Wernicke’s aphasia: fluent but meaningless expressive language, all other aspects of language impaired
d. conduction aphasia: damage to arcuate fasciculus; fluent expressive language and intact receptive language + reading comprehension, impaired naming/repeating/writing/reading out loud
e. Transcortical aphasia: damage to watershed areas (connections to other cortical regions); nonfluent in motor but fluent in sensory expressive language, intact in motor but impaired sensory receptive language, intact repeating, everything else varies
contrast the following language syndromes:
a. Pure anomia.
b. Pure alexia
c. Pure agraphia
a. Pure anomia: impaired naming
b. Pure alexia: impaired reading
c. Pure agraphia: impaired writing
Global aphasia is localized to the entire perisylvian region, and is primarily caused by occlusion of the distal stem of the…
MCA prior to its bifurcation
associated with contralateral hemiplegia and hemisensory loss
Brocas aphasia is most commonly caused by occlusion of the…
… superior division of the MCA
Associated with contralateral hemiplegia. Patients tend to be aware of the deficit.
Wernicke’s aphasia is most commonly caused by occlusion of the…
… inferior division of the MCA
Associated with contralateral hemisensory loss. Patients are often unaware of the deficit.
Occlusion of which arteries cause each of the following language aphasias?
a. global aphasia
b. Broca’s aphasia
c. Wernicke’s aphasia
a. global aphasia - distal MCA prior to its bifurcation
b. Broca’s aphasia - superior division of MCA
c. Wernicke’s aphasia - inferior division of MCA
pure alexia is usually caused by an infarct of which artery?
pure alexia = impaired reading only, localized to temporo-occipital region
classically caused by left (dominant) PCA infarct
contrast the following primary progressive aphasias:
a. Nonfluent/agrammatic
b. Semantic variant.
c. logopenic variant
a. Nonfluent/agrammatic: loss of grammar and sentence structure, associated with frontotemporal degeneration
b. Semantic variant: loss of word, meetings, associated with frontotemporal degeneration
c. logopenic variant: difficulty finding words + impaired repetition, associated with Alzheimer’s
receptive versus expressive aprosodia
receptive aprosodia: loss of ability to identify emotion, based on tone of voice (non-dominant equivalent of Wernicke’s area)
expressive aprosodia: loss of ability to use tone of voice to convey emotion (non-dominant equivalent of Broca’s area)
