B7.046 Cognition: A Clinical Perspective Flashcards
definition of dementia
cognitive deficits impairing social or occupational functioning
- acquired (after 18)
- persistent
- multiple cognitive domains
primary sensory and motor cortical regions
frontal eye fields motor cortex somatosensory cortex auditory cortex visual cortex
first order association cortices
prefrontal cortex
auditory unimodal association cortex
somatosensory unimodal association cortex
visual unimodal association cortex
multimodal association areas
anterior association area
posterior association area
functions of perceptual association areas
integrate sensory information from the unimodal cortices
perceptual association areas
parietal association area
temporal association area
function of anterior association area
executive function, planning
perceptual pathways and their functions
dorsal: recognition of relationships between objects
ventral: object recognition
function of limbic association area
memory (and retrieval of memories), motivation
example pathway through the cortex
- sensory information to primary sensory cortex
- information processed in corresponding unimodal association cortex
- information from multiple unimodal association cortices converges on multimodal association cortex and information is processed together
- information is integrated with limbic association area to recognize the stimuli based on memories
- sensory input feeds into anterior association cortex to begin executive planning based on the reaction to the stimuli
- planning information sent to prefrontal cortex
- prefrontal cortex influences primary motor cortex and corticospinal tracts descend with information about movement based on the plan made in the anterior association cortex
anterior brain
executive and motor functions
posterior brain
perceptual and sensory functions
left brain
symbolic reasoning
-language, math, serial processing of symbols
right brain
pattern reasoning
-visual and spatial processing, looking at things as a whole
what is brain dominance?
the side of your brain where language processing lives (majority of people are L brain dominant)
distribution of brain dominance in the population
right handed people - L brain dominant
left handed people - 70% L brain dominant, 15% R brain dominant, 15% both hemispheres
midline brain
memory processing
pattern of deficits in cortical lesions
diffuse vs focal
dominant vs non dominant
anterior vs posterior
clinical evaluation of deficits with suspected cortical lesion
history
mental status exam
elementary neuro exam
components of history taking in evaluation of suspected cortical lesions
behavioral problems memorizing lists balancing check books anomia getting lost driving (non-dominant hemisphere problem)
most common mental status exam
folstein mini-mental status exam
typical score on folstein mini-mental status exam
most people get 30/30
if below 28, something is wrong
most useful way to use folstein mini-mental status exam
look at PATTERN of deficits, not sure score functions tested: memory language constructions
breakdown of points in folstein mini-mental status exam
majority memory and language (dominant and midline brain)
1 point from constructions (non dominant brain)
dominant/memory brain biased, may need to supplement non dominant tests
limitations of clinical mental status exam
good: -symbolic reasoning (dominant) -memory -perceptual bad: -executive (motor) -pattern reasoning (non-dominant)
tests for executive function
word fluency (name >15 animals in 1 min) trails test
tests for construction
draw a cube
overlapping pentagons
tiles
cortical vs subcortical damage
when subcortical systems are affected, elementary neuro exam is abnormal (typically in motor findings)
motor signs in subcortical disease
rigidity
weakness
what is the elementary neuro exam
parts of the neuro exam that don’t deal with mental status
Alzheimer’s disease
diffuse cortical dementia
idiopathic, neurodegenerative disease
pathologically characterized by plaques and tangles
progression of alzheimer’s
lesions begin in the medial temporal lobe (hippocampus area)
lesions spread without obvious symptoms for many years
mild cognitive impairment manifests once lesion has spread well into temporal and frontal lobes (first symptom is typically short term memory dysfunction)
dementia manifests once a large amount of the cortex is affected
motor areas typically spare until very late in disease
incidence and prevalence of alzheimers
increases with age
worldwide projections increasing drastically over time (epidemic)
centrally acting cholinesterase inhibitors in Alzheimers
targets early involvement of diffuse cholinergic projection system in the basal forebrain minor benefit (if any) drugs: tacrine, donepezil, galantamine, rivastigmine
NMDA receptor antagonists in Alzheimers
mechanism is to inhibit glutamate receptor overactivity that could lead to an influx of Ca2+ and resulting excitotoxicity
minor benefit
drug: memantine
top 3 types of dementia
ortical 1. alzheimers subcortical 2. vascular dementias 3. diffuse lewy body dementia
more uncommon cortical dementia
frontotemporal
- anterior cortex affected first
- memory is ok but dysexecutive symptoms are seen (inappropriateness)
components of language processing area of brain
in dominant hemisphere
Wernicke’s (semantic area) : multimodal center that decodes auditory input, distinguishes words
Broca’s (encoding and grammar area) : turns ideas into sounds
repetition area: connects Wernicke’s and Broca’s
pathways in language processing
- auditory input goes into auditory cortex and then into Wernicke’s area
- Wernicke’s area sends projections into posterior association areas
- Wernicke’s also has a connection with Broca’s area, the repetition area
- Broca’s area receives input from Wernicke’s and anterior association areas
- Broca’s area sends input into the motor cortex to allow a person to speak
components of a language assessment
fluency
comprehension
repetition
Broca’s aphasia
non-fluent speech
comprehension intact
no repetition
Wernicke’s aphasia
fluent speech (but non sensical) no comprehension (can't follow commands) no repetition
conduction aphasia
fluent speech
comprehension intact
no repetition
trans-cortical sensory aphasia
disconnects Wernicke’s area from posterior association centers
fluent speech
no comprehension
CAN repeat
trans-cortical motor aphasia
disconnects Broca’s area from anterior association centers
non-fluent speech
comprehension intact
CAN repeat
common causes of aphasias
watershed strokes
