Cortical Lesions Flashcards
Layers of cortex vs hipoocampus
6 vs 3
Diffuse cortical dysfunction
denerative (ie Alzheimers), metabolic (hypoxia)
Focal lesions
vascular (stroke), traumatic (contusion), neoplastic (tumor)
TBI
- leading cause of disability in adults
- mostly closed (blunt ) head injury, occasionally penetrating
- Cortex damage via direct injury =contusion
- Bleeding can also occur: intraparenchymal hemorrhage, subdural, epidural hemotomas
- Widespread white matter damage: diffuse axonal injury can occur
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
- deficits in motor func (UMN), language, prosody (emotional content of language/inflection–right hem inferior frontal gyrus), neuropsychiatric disorders
- ->worse if bilateral
Frontal Lobe syndromes
- disinhibition (orbitofrontal cortices)
- executive dysfunction (dorsolateral prefrontal cortices)
- Apathy (medial frontal cortices)
Disinhibition
- frontal lobe damage
- impaired comportment (appropriate social behavior)
- irritability, loss of empathy, impulsivity (pathological gambling, excessive spending), hypersexuality, hyperphagia, violence
Executive Dysfunction
- frontal lobe damage
- perseveration (impaired capacity to shift responses appropriately; test w/ alternating sequences test)
Apathy
- at cortical level, motivation subserved by medial frontal cortices, including anterior cingulate gyrus
- apathy, abulia, and most severe akinetic mutism
Temporal lobe lesion
- Minor effects on audition, but major effects on language, prosody, memory, and emotion
- effects on emotion result from irritative lesions of the cortex that cause epilepsy
- Wernicke’s aphasia: fluent, paraphasic speech w/ impaired auditory comprehension, repetition, and naming
- Sensory aprosody: inability to comprehend prosody of others
- emotion: limbic system (Papez circuit), subserves basic emotions (fight-flight, appetite, sexual reproduction)
Temporal lobe epilepsy
- related to focal cortical lesion in temp lobe that produce complex partial seizures
- TLE produces lasting changes in behavior bc of ongoing electrical activity that rewires temporolimbic circuitry
- Deepened emotionality, hyperreligiosity, philosophical interest, hypergraphia
Parietal lobe lesion
HEMINEGLECT (inattention to contralateral space)
Hemineglect
- usually caused by right parietal hemisphere lesions, with inattention to left side of space
- right hemisphere has capacity to attend to both sides of space, while the LEFT can only attend to contralateral space
- left hemineglect= more sever and lasting than right
visual field deficits vs visual agnosia
Visual field deficits produced by occipital lesions: hemianopia and quadrantanopia are most common; absence of vision.
Visual agnosia: visual image is seen normally but not adequately recognized (requires dorsal and ventral visual association cortices
Prosopagnosia
-can’t recognize faces
