Cortical Lesions Flashcards
Cortical Disorders Major Category
Diffuse
Focal
Cortical Disorders Diffuse
e.g. degenerative (Alzheimer’s Disease), metabolic (hypoxia)
Cortical Disorders Focal
. vascular (stroke), traumatic (contusion), neoplastic (tumor)
Frontal Lobe Functions
Voluntary movement Language production (left) Motor prosody (right) Comportment Executive function Motivation
Temporal Lobe Functions
Audition Language comprehension (left) Sensory prosody (right) Memory Emotion
Parietal Lobe Functions
Tactile sensation Visuospatial function (right) Attention (right) Reading (left) Writing (left) Calculation (left)
Occipital Lobe Functions
Vision
Visual perception
Visual recognition
Frontal lobe lesions produce deficits in motor function (upper motor neuron involvement), language, prosody, and neuropsychiatric disorders (frontal lobe syndromes)
In general, neurobehavioral effects are more florid and persistent with bilateral lesions
Frontal Lobe Syndromes
Disinhibition – orbitofrontal cortices
Executive dysfunction – dorsolateral prefrontal cortices
Apathy – medial frontal cortices
Considerable evidence implicates damage to the frontal lobes as having an impact on the propensity for: ________
violence
This is a disturbance of comportment, the capacity to maintain an appropriate behavioral repertoire in the face of social situations where limbic drives are influential and impulse control is critical
Patients may show irritability, loss of empathy, impulsivity (pathological gambling, excessive spending, etc.), hypersexuality, hyperphagia, and violence
Disinhibition- loss of social grace
orbitofrontal cortices
A term that implies frontal lobe damage
One feature of frontal lobe damage is perseveration, an impairment of the capacity to shift responses appropriately
The alternating sequences test can demonstrate perseveration, as in this example from an AD patient
Executive Dysfunction- Plan/ coordinate
dorsolateral prefrontal cortices
At the cortical level, motivation is mainly subserved by the medial frontal cortices, including the anterior cingulate gyrus
Clinical syndromes include apathy, abulia, and most severely, akinetic mutism
Apathy- you just quit
medial frontal cortices
*Cingulate gyrus may be the center of will
Lesions of the temporal lobe have minor effects on audition, but often major effects on ___________
language, prosody, memory, and emotion
In terms of the emotions, the effects of temporal lobe lesions result from irritative lesions of the cortex that cause epilepsy
____________ is usually caused by right hemisphere lesions, with inattention to the left side of space
The lower drawing was done by a man with a recent right parietal infarct
Hemineglect
Visual Agnosia
Visual agnosia is a failure to recognize objects that are adequately seen
Recognition requires the dorsal and ventral visual association cortices
Examples: object agnosia (left occipitotemporal), prosopagnosia (right occipitotemporal), achromatopsia (bilateral occipitotemporal), and simultanagnosia (bilateral occipitoparietal)
In terms of the emotions, the effects of temporal lobe lesions from irritative lesions of the cortex that cause ___________
epilepsy
Irritative lesion= hyperactive cortex
The right hemisphere has the capacity to attend to both sides of space, whereas the left can only attend to the contralateral space
Right vs Left Lesion?
Thus a right parietal lesion will only permit surveillance of the right hemispace
Left hemineglect is more severe and lasting than right hemineglect
The aphasia resulting from damage to Wernicke’s area
Fluent, paraphasic speech with impaired auditory comprehension, repetition, and naming
Wernicke’s Aphasia- Temporal
Cannot hear inflections of speech
Analogous to Wernicke’s aphasia, sensory aprosody is the inability to comprehend the prosody of others
Sensory Aprosody
Limbic lesions often disturb ____________-
Papez circuit: basic emotions
emotional function
Common form of epilepsy, related to focal cortical lesions that produce complex partial seizures
Many behavioral phenomena can be associated with these seizures
Temporal Lobe Epilepsy (TLE)
Considerable evidence exists to show that __________ produces lasting changes in behavior because of ongoing subclinical and clinical electrical activity that rewires temporolimbic circuitry
TLE
Hemineglect is usually caused by
RIGHT hemisphere lesions- prototype parietal lobe syndrome
Bad attention to left side of space
Thus a right parietal lesion will only permit surveillance of the right hemispace
Left hemineglect is ________________–
more severe and lasting than right hemineglect
A right parietal lesion will _______________
Left hemineglect is more severe and lasting than right hemineglect
only permit surveillance of the right hemispace
Occipital lesions produce visual field deficits: most common are ____________
hemianopia and quadrantanopia
