Higher cortical functions and syndromes Flashcards
1
Q
Higher cortical functions
A
- Processes by which primary sensory info is integrated into complex concepts and ideas that can be remembered and used to formulate a new action plan
- Carried out in association cortices
- Primary motor and sensory cortices have unimodal association cortices which are connected to multimodal association cortices (which then sends info to the prefrontal cortex)
- The purpose of association cortices are to interpret and integrate sensory information
2
Q
Regions involved in higher functioning
A
- Declarative memory: temporal lobe
- Language production: prefrontal cortex (broca’s)
- Language comprehension: posterior part of superior temporal cortex, near the face area of primary motor cortex (wernicke’s)
- Visuospatial info: parietal cortex
- Executive functions (problem solving, verbal reasoning): prefrontal cortex
3
Q
Hemispheric specialization
A
- Many motor and sensory functions are carried out by both R and L cortex symmetrically, connected via corpus callosum
- But some functions are mainly processed in one hemisphere
- In hemispheric specialization, the dominant hemisphere refers to the side that is superior for performing the task while the non-dominant hemisphere is less involved
4
Q
Handedness
A
- 99% of R handed individuals are left hemisphere dominant, so the L hemisphere controls complex motor tasks for both right and left limbs
- The R cortex carries out simple motor tasks on the left side only
- In L handed individuals the motor function is distributed across both hemispheres more evenly, thus there is less of a dominant hemisphere
5
Q
Skills involved in hemispheric specialization
A
- Left hemisphere: language, reading, writing, calculations
- Right hemisphere: visuospatial ability, facial recognition, intonation of speech, music, appreciation of humor
6
Q
Memory
A
- The ability to encode, store, and recall info
- Medial temporal lobe (hippocampus, parahippocampal gyrus), and midline structures of diencephalon (dorsal-medial and anterior nucleus of thalamus and mammillary bodies) all involved in memory
- Types of memory: sensory, short-term, long-term
7
Q
Sensory memory
A
- Sensory: everything we see or hear immediately after it occurs
- Degrades quickly (after .5 to 3 sec), visual memory degrades quicker than auditory
8
Q
Short term memory
A
- Short-term: info we attend to or are thinking about, limited capacity of 5-10 items
- Can be recalled within 30 sec -1 min of learning, but transferring sensory memory to short-term memory requires attention to stimulus (can eventually go to long-term)
- Short term memory can be enhanced by rehearsal or chunking
9
Q
Long term memory
A
- Most info in short term memory is never converted to long term memory
- Consolidation from short term memory to long term occurs w/in a few minutes of being received
- Stores info for hrs to years, unlimited storage capacity
- Molecularly, involved in changes in synaptic efficacy (LTP or LTD) and structural modification of dendritic spines/synaptogenesis
10
Q
Types of long term memory
A
- Declarative (explicit): conscious access to facts
- Medial temporal lobe (hippocampus, midline thalamus, mammilary bodies)
- Nondeclarative (implicit): knowledge that does not require conscious access, such as motor skills, cognitive skills (reading), classical conditioning, problem solving
- Involves diffuse brain regions: amygdala, cerebellum, frontal and parietal lobes
11
Q
Amnesia
A
- Usually loss of declarative memory
- Anterograde: inability to convert short term into long term memories (cannot form new memories)
- Seen in global cognitive deficits (AD) or trauma, typically involves hippocampus
- Retrograde: loss of pre-existing memories before an injury/disease (cannot recall things after an accident)
- Usually involves temporal lobe and other cortical areas where long term memory is stored
12
Q
AD and Korsakoff’s syndrome
A
- AD: progressive short term memory loss w/ behavioral and language problems (anterograde amnesia)
- Bilateral neuronal degeneration of neocortex, basal ganglia, hippocampal, and selective cholinergic and noradrenergic loss in forebrain and brain stem
- Abundance of neurofibrillary tangles and plaques all relative for the pt age
- Korsakoff’s syndrome: due to lack of vit B1 (thymine) and linked to chronic etoh use (can also be due to stroke)
- Affects midline structures of thalamus and mammillary bodies
- Loss of declarative memory but preservation of non declarative memory (similar to medial temporal lobe damage)
13
Q
Language
A
- Lateralized to left hemisphere for most people (95% of R handers and 60-70% of L handers)
- Broca and wernicke’s areas connected via arcuate fasciculus
- Connections of frontal cortex via corpus callosum allow the non-dominant hemisphere to participate in language processing (recognition and production of the emotionally appropriate expression or tone of speech)
14
Q
Broca’s aphasia
A
- Primary deficit in language output/production, comprehension is intact
- Speech is effortful, delayed, and slow w/ decreased spontaneous speech
- Cannot repeat phrases, speaks in short phrases (agrammatism)
- Typically due to infarct of superior division of MCA or trauma to broca’s area, often accompanied by paralysis of right upper limb
15
Q
Wernicke’s aphasia
A
- Impairment of comprehension of spoken or written speech
- Fluent, spontaneous speech but meaningless content
- Cannot repeat words or phrases, do not respond to commands
- Usually due to infarct of inferior division of MCA
