Lecture 3.1 Flashcards
What are some older procedures for localizing language functions?
phrenology
EEG
lesion studies
electrical cortical stimulation
What is phrenology?
certain bumps/regions in the skull associated with certain characteristics
How did soldiers returning from war contribute to localizing language functions?
people dying with specific brain lesions allowed us to study
also expanded surgical interventions
What is meant by dichotic listening?
right ear has advantage for hearing
since auditory pathways are contralateral and language areas are on the left side of brain
- right ear can better detect linguistic information
What are some more recent procedures for localizing language functions?
MRI/fMRI
ultrasound
CT
PET
What procedures provide static views for localizing language functions?
MRI
PET
SPECT
What procedures provide dynamic views for localizing language functions?
fMRI
sonography
What did Hans Lukas Teuber say about localization of function?
just because we can see where a particular function is coming from doesn’t mean it is the only place it comes from
many areas work together, other areas connected to primary region
What are the components of the brain (5)
telencephalon diencephalon mesencephalon metencephalon myelencephalon
What are the components of the CNS?
cerebral hemispheres
brainstem
cerebellum
spinal cord
What composes the brainstem?
midbrain
pons
medulla
What are the protective layers from external to internal?
skin
muscles
cranium
meningeal layers (dura, arachnoid, pia)
How significant is the resource use of the cerebrum?
weighs less than 2 kg yet uses 20% O2 and 25% vascular supply
Which meningeal layer has the most vascular supply?
subarachnoid space
What is the difference between cortical and subcortical areas?
cortical = on the cortex, outer layer, grey matter, complex functions, multiple layers of neurons
subcortical = beneath cortex, white matter, more primitive functions
What are the 3 types of interconnecting fibre tracts?
commissural - one hemisphere to another
association - within the same hemisphere
- long = between lobes
- short = within lobe
projection - ascending (to cortical areas) or descending (from cortical areas)
What language dominance patterns are shown by right handed people (90-95% population)?
95% of right handers show left hemisphere language dominance
What language dominance patterns are shown by left handed people (7-10% population)?
65-70% show left hemisphere language dominance
5-10% show right hemisphere language dominance
20-35% show bilateral language dominance
What is Exner’s area?
in premotor cortex
- foot of 2nd frontal convolution
BA 6, parts of 8, 9
right above Broca’s area
helps control writing, printing, and typing
- area contains knowledge of how to make movements of the hands and fingers for these functions
damage = motor dysgraphia
What is the importance of the parahippocampal gyrus?
important for memory
What is the superior longitudinal fasiculus?
long association fibre
- white fibre tract
sends info from one lobe to another within left hemisphere
from around sylvian fissure in anterior and posterior directions
What is BA 45+45?
Broca’s area
frontal lobe
LANGUAGE area
memories of motor patterns for speech production and grammar
What happens when there is damage to BA 44+45?
non-fluent output/aphasia: 5 words or less average utterance
laborious speech, poor reading aloud skills, poor repetition
often coexists with apraxia (nonverbal and speech)
What is the primary motor area?
BA 4 - precentral gyrus
motor homunculus
just above and in front of Broca’s area
voluntary movements for contralateral side of the body
Describe the motor homunculus.
on precentral gyrus (BA4)
size of cortical area related to amount of control required for motor movements
legs and feet on medial side
upper head, face, hands, and mouth on lateral aspect inverted
large area of face and hands laterally
What is the inferior-lateral portion of the premotor cortex?
BA 6 (part of 8)
stimulation = movement
- great amounts of stimulation necessary to produce some degree of movement
What is the frontal eye-field?
parts of BA 6, 8, 9
controls conjugate eye movement (eye scanning) independent of visual stimuli
especially towards contralateral side
What is the supplementary motor area?
anterior to precentral gyrus
initiation of spontaneous speech and partial complex movements of upper limbs (fingers, arms, limbs)
some involvement in stuttering and speech production (sensorimotor planning of oral movements)
What is the prefrontal cortex?
anterior to precentral areas
includes BA 8-12 and 46
numerous association efferent and afferent fibre pathways with thalamus, hypothalamus, corpus striatum, and other areas of cerebral cortex
initiative, emotionality, regulator of depth of feelings, judgement, attention
What are some major components of the temporal lobe?
prefrontal cortex supplementary motor area Exner's area frontal eye field precentral gyrus premotor cortex Broca's area
What are some major components of the temporal lobe?
superior temporal gyrus
Wernickes area
angular gyrus
What is the superior temporal gyrus?
BA 41 and 42
aka:
- primary auditory cortex
- Heschl’s gyrus
- transverse temporal gyri
recognition/perception of complex auditory stimuli (speech)
- receives projections from medial geniculate body
receives input from left and right ear
What results from damage to superior temporal gyrus?
auditory verbal agnosia or pure word deafness
receiving acoustic stimuli but can’t tell you what it means
What is Wernicke’s area?
auditory association cortex
recall and interpret spoken language
BA 22
What is the arcuate fasciculus?
connect Wernicke’s area to Broca’s area
What is the angular gyrus?
BA 39 stores symbols for reading, writing, calculations/arithmetic
processes orthographic and abstract word forms
receives rich visual projections from visual cortices
What kinds of impairments could result from damage to the angular gyrus?
alexia (reading), agraphia (writing), acalculia (calculating)
jargon aphasia (in combination with Wernicke’s area)
conduction aphasia (in combination with arcuate fasiculus)
What is Wernicke’s aphasia?
when you can understand the info but have a hard time assigning meaning
lengthy speech production but makes no sense
What occurs with anterior temporal lobe damage?
impaired semantic knowledge
processing of vowel change in verbs (ex. sleep-slept)
What occurs with left side temporal lobe damage?
naming deficits
What occurs with posterior temporal lobe damage?
impaired phonological word form access
What are some key features in the parietal love?
supramarginal gyrus
post-central gyrus
secondary somesthetic area
What is the supramarginal gyrus?
BA 40
semantic/syntactic/phonological sentence processing
integrates visual and somesthetic input
What would occur with injury to the supramarginal gyrus?
jargon aphasia
constructional apraxia
poor gesture use/comprehension
scanning and reading difficulties
What is the post central gyrus?
BA 1,2,3
primary somatosensory cortex
receives ipsilateral and contralateral afferent information
receives projections from ventral nuclei of thalamus
What is the secondary somatosensory area?
BA 5,7
receives input from BA 1,2,3 and dorsal thalamus
discriminative touch
integration of info about form, position, and temporal changes
What occurs in the occipital lobe?
integration of visual and auditory and sensory information
What are some important structures of the occipital lobe?
primary visual cortex
BA 18,19
What is the primary visual cortex?
BA 17
receives afferent fibres from lateral geniculate body of thalamus
also ipsilateral temporal retina and contralateral nasal retina
- right half visual field = left visual cortex
- left half of visual field = right visual cortex
What is BA 18,19?
receives afferent fibres from primary visual cortex and thalamus
real time integration of past visual experiences with recognition of what is received from visual sensory system
What would occur with injury to BA 18,19?
visual agnosia alexia without agraphia colour agnosia prosopagnosia object agnosia
What is agnosia?
percept stripped of its meaning due to either:
- disconnect between primary sensory cortex and association cortex
- damage to association cortex
can receive and describe information but can’t interpret it
How does the temporal half of the left retina map?
onto nasal visual field of left eye
project ipsilaterally back to primary visual cortex
How does the nasal half of the right retina map?
onto temporal visual field of right eye
contralateral projections back to primary visual cortex
