cortical lesions Flashcards
compare cortex of temporal lobe to the rest of the brain
The six-layered neocortex makes up most of the cortical surface, but the hippocampus in the temporal lobe is comprised of phylogenetically older three-layered allocortex
Functions of frontal lobe
Voluntary movement, Language fluency (left), Motor prosody (right), Comportment , Executive function , Motivation
functions of parietal lobe
Tactile sensation, Visuospatial function (right), Attention (right), Reading (left), Writing (left), Calculation (left)
functions of temporal lobe
Language comprehension (left), Sensory prosody (right), Memory (hippocampus) , Emotion Language comprehension (left), Sensory prosody (right), Memory (hippocampus) , Emotion
functions of occipital lobe
Vision, Visual perception, Visual recognition
diffuse vs focal cortical lesions
diffuse: Alzheimers and hypoxic injury. Focal: vascular disease (stroke), traumatic brain injury (contusion, hemorrhage), and neoplasia (brain tumor).
Cognitive disfunctions from stroke
from aphasia, amnesia, visuospatial impairment, hemineglect, agnosia, and a host of related syndromes
What kind of lesions are seen with tramatic brain injury
Along with the diffuse effects of brain injury, known as diffuse axonal injury that occurs in the white matter, a wide range of focal cortical lesions are seen. Contusions are common in frontal/temporal lobes
What kind of lesions are seen with brain tumors
Often present with focal cognitive dysfunction. Benign tuors do not invade brain, while malignant tumors cause infiltration.
What does damage to Broca’s area result in?
Damage to brocas area in the left frontal lobe causes Aphasia.
What is motor aprosody
Lesions to the right frontal lobe (in the same region as where Broca’s area is on the left)- causes an inability to inflect speech with emotion
What are the three frontal lobe syndromes
disinhibition from orbitofrontal lesions, executive dysfunction from dorsolateral prefrontal lesions, and apathy from medial frontal lesions. These syndromes are all more florid and persistent with bilateral lesions.
What is disinhibition
Disinhibition is a disorder of comportment, whereby a person can no longer adequately integrate limbic drives into an appropriate behavioral repertoire. Irritability, loss of empathy, impulsivity, hypersexuality, hyperphagia, and even violence can be sequelae.
What does executive dysfunction look like
Defects in the capacity to plan, carry out, and monitor a sequential goal-directed action.
What is apathy
loss of motivation, and more severe forms are known as abulia and akinetic mutism. In these cases, an erosion of initiative may be so dramatic that it seems the individual’s will has been diminished.
Damage to Wernickes area causes what?
Wernicke’s aphasia, in which auditory comprehension is impaired because of a lesion in the posterior region of the left superior temporal gyrus
What is sensory aprosody and what causes it
Diminished ability to comprehend emotional inflection of speech. Due to a lesion in the right hemisphere analogue of Wernickes area (superior temporal gyrus)
Where is the hippocampus and what is its function
tempral lobe- functions in new learning. Damage to this area causes amnesia (new learning deficity)
Limbic system- location and function
Located in temporal lobe and diencephalon- functions in emotion
temporal lobe epilepsy symptoms
deepened emotion, hypergraphia, personality alterations, due to changes in temporal lobe/limbic system
What is hemineglect
failure to report, respond to, or orient to sensory stimuli that cannot be explained by primary sensory dysfunction. Occurs after damage to parietal lobe. Rigth parietal hemineglect can cause inattention to left side of body or extrapersonal space. Left parietal hemineglect causes a disabling disorder of cognition
compare the right vs left pareital lobes capacity to attend to space
lThe right hemisphere has the capacity to attend to both sides of space, whereas the left can only attend to the contralateral space
What are the occipitotemporal and occipitoparietal cortices functions
the occipitotemporal is the “ventral stream” or “what” system. occipitoparietal is the “dorsal stream” or “where” system
Visual agnosia vs visual field defect
Visual agnosia is a recognition deficit due to damage to the ventral or dorsal stream. Can include object agnosia (left occipitotemporal lesions), face agnosia (right occipitotemporal lesion). Visual field deficits produce an absence of vision, while visual agnosia means visual image is seen but not recognized
What is cerebral disconnection
Lesions disconnect one part of brain from another
Example of linguistic disconnection
conduction aphasia
What is alexia
stroke damages left occipital lobe and splenium of corpus callosum. This disconnects the visual system from language system, so person can write but not read.
