Week 8 Higher Cortical Functions and Syndromes Flashcards
(18 cards)
Define higher cortical function.
Higher cortical functions are processes by which primary sensory information is integrated into complex concepts and ideas that can be remembered and used to formulate a new action plan
- example: memory, language, praxis, visuospatial info, execution fxns, verbal reasoning, attention, social behaviors
- carried out in association cortices
List the higher cortical functions that can be localized to specific cortical regions.
- declarative memory: temporal lobe
- language production: prefrontal cortex (broca’s)
- language comprehension: Wernicke’s area
- visuospatial info: parietal cortex
- execution functions: prefrontal cortex
What are some skills and examples of hemispheric specialization?
- handedness
- left hemisphere: language, reading & writing, calculations
- right hemisphere: visuospatial ability, facial recognition, receptive and expressive rhythm and intonation of speech
- music
- appreciation of humor
What are brain regions that are critical for memory formation?
- medial temporal lobe (hippocampus, parahippocampal gyrus)
- midline structures of the diencephalon (dorso-medial and ant. nucleus of the thalamus and mammilary bodies)
What are the three stages of memory processing?
- sensory memory
- degrades in .5 to 3 secs - short term memory
- records info we attend to or think about (7-10 items)
- recall info for 30secs-1min
- can be enhanced by rehearsal or chunking - long term memory
- consolidation of info from short term to long term occurs within a few mins of being received
- allows for continual storage of info for hrs to years
- unlimited storage capacity
- involves changes in synaptic efficacy (LTP or LTD, structural modification of dendritic spines and synaptogenesis)
What is declarative memory?
Conscious access to facts about our lives and the world around us
- involves the medial temporal lobe including hippocampus, midline thalamus, mammilary bodies
- eg. patient HM- anterograde amnesia
What is non declarative memory?
Knowledge that doesn’t require conscious access such as motor skills or cognitive skills, classical conditioning, problem solving
-involves diffuse brain regions including amygdala, cerebellum, frontal and parietal lobes
What is anterograde amnesia?
- inability to convert new short term memories into long term so that info in short term memory is lost
- can be part of global cognitive deficit like Alzhemier’s disease, or specific event like head trauma, stroke, or surgery that typically involves the hippocampus
What is retrograde amnesia?
- loss of pre-existing memories before an injury or the onset of disease
- can remember new facts but unable to recall things prior to some point in time
- most likely involves areas of temporal lobe as well as other cortical areas where long term memories are stored
Describe Korsakoff’s syndrome.
- a neurological disorder caused by a lack of thiamine (Vit B)
- linked to chronic alcohol abuse, also can be by stroke, tumors and trauma
- involves diencephalon, mostly the dorsomedial nucleus of thalamus and mammilary bodies
- loss of declarative memory but preservation of non declarative memory
Describe the hemispheric lateralization of language and speech.
- Wernike’s area in posterior portion of superior temporal lobe
- Broca’s area: located inf/posterior frontal cortex
- nondominant hemisphere is important in the recognition and production of the emotionally appropriate expression or tone of speech
Define aphasia.
impairment of language communication due to a brain dysfunction
Describe the features of Broca’s aphasia.
- primary deficit in language output/production
- language comprehension is intact
- speech is effortful, delayed, and slow with a decrease in fluency of spontaneous speech
- agrammatism: short/truncated phrases, can’t repeat phrases
- typically caused by infarct of superior division of MCA or trauma to Broca’s area
- often accompanied by paralysis of right upper limb
Describe the features of Wernicke’s Aphasia.
- impairment of comprehension of spoken, written speech
- fluent, spontaneous speech is normal but meaningless or caontains unintelligible content. can’t repeat words or phases
- patient’s don’t respond appropriately to commands
- typically caused by infarct of inferior division of MCA
Describe hemispheric specialization of spatial processing and attention.
- left hemisphere responds to stimuli to right side of the body or in right visual field
- right hemisphere responds to stimuli from both sides
- lesions in right hemisphere lead to prominent and long lasting deficits in attention to contralteral side, while left hemisphere lesions results in mild deficits
Describe hemispatial neglect syndrome.
- exhibit profound neglect for contralateral half of external world as well as contralateral side of their body
- typically from lesions of the right parietal or frontal cortex due to sudden infarct or trauma
What are the areas of the prefrontal cortex involved in executive function processing?
- dorso-lateral prefrontal cortex
- orbito-frontal cortex
- anterior cingulate gyrus
What is the dorso-lateral prefrontal circuit? What is an example of a clinical syndrome associated with the dorso-lateral prefrontal circuit?
- originates from prefrontal cortex and projects to caudate
- involved in working memory, planning ahead toward a defined goal, temporal ordering of events, judgement, abstract reasoning
- Frontotemporal dementia (FTD): caused by degeneration of frontal lobe which may extend back to the temporal lobe- impaired reasoning, easily distracted, poor organizational strategies, socially inappropriate behavior
