Lecture 1 Flashcards
Aphasia
Acquired disorder of language caused by brain damage
May impact comprehension of language, expression of language, or both
May involve any modality (speech, writing, etc)
Clinically Important Consideration
Historically confusing disorder; involves multiple disciplines, and is often thought of demographically as “a disorder associated with aging”
Scientifically Important Consideration
Relationship between the brain & language; correlation between affected areas of the brain with lost or impaired language vs. unimpaired areas
Allow us to query whether specific areas of the brain control or modulate particular language functions
Early Perspectives on Aphasia
Multiple early misunderstandings: some thought the ventricles controlled cognition & some thought aphasia resulted from a paralyzed tongue
Gesner
1770: coined term “speech amnesia”
German anatomist/phrenologist who 1st suggested that language was localized in the brain along with other intellectual functions
Phrenology
Associates mental & intellectual functions topographically on the skull
Phrenological Organs
37 faculties
Johann Kaspar Spurzheim
Paul Broca
1824-1880
French neurosurgeon
1st to offer clinical & pathological evidence relating frontal lobe & left brain to language production
Research was especially fixated on lower portion of frontal lobe: area concerned with motor speech (aka Broca’s area)
Broca’s Work
Aphemia
Aphemia
Reduced speech fluency
Agrammatic, telegraphic speech
Many language production errors
Limited impairment of comprehension of spoken language
Carl Wernicke
1848-1905
German neuropsychiatrist
1st to describe a type of aphasia opposite in part to that of Broca’s work
His work purported that a different type of aphasia resulted from lesions in posterior portion of left superior temporal gyrus
Wernicke’s Work
Sensory aphasia; proposed that other types of aphasia existed: TCM, conduction aphasia, TCS
Handedness Theory
1936: Johannes Nielson suggested that language was in hemisphere opposite of preferred hand; research has discounted hypothesis: handedness not a reliable indicator of hemispheric language dominance
~85% of general population is right-handed; 15% is left-handed
Language Location in the Brain
Language is left-dominant for majority of world’s population
~15% of the (15% left-handed) are right hemisphere dominant for language
Cerebrum
The final integrative & executive structure of the nervous system; responsible for all higher-brain functions
Higher Brain Functions
Everyday thinking, logical reasoning, abstract reasoning, mathematical reasoning, memory, speaking, language production, artistry, scientific achievement, language comprehension, judgment, emotional experience, attention, problem solving, executive functioning
About the Brain
Contains billions of neurons with trillions of synapses
Weighs 3-3.5 pounds
Comprised of 6 layers w/ outermost layer consisting of gray matter
2 hemispheres connected by thick bands of long fibers (axons)
Regions w/ in the hemispheres connected by shorter association fibers
Surface is comprised of gyri & sulci
Gyri
Hills, folds, & convolutions on the brain surface
Sulci
grooves, valleys, & fissures on the brain
LCF
Longitudinal Cerebral Fissure
Separates the left/right hemispheres
Fissure of Rolando
aka Central Sulcus
Runs laterally, downward, & forward dividing the anterior half of the brain from the posterior half
Lateral Cerebral Fissure
aka Sylvian Fissure
Moves laterally and upward
Perisylvian Area
Regions surrounding this area are especially involved in speech, language, & hearing
Cerebral Lobes
Each cerebral hemisphere divided into 4 lobes: frontal, parietal, temporal, occipital
Each lobe associated with predominant functions
Frontal Lobe
Extremely important lobe for speech/language; largest lobe (1/3 of cortical surface)
Precentral Gyrus & the Frontal Lobe
Major portion of the primary motor cortex via the PS
Movements modified by EPS
Controls voluntary movements on opposite side of body
Anterior to motor strip is premotor area & supplementary areas
Prefrontal cortex
intellectual tasks (thinking, reasoning, decision-making, etc.)
Other important gyri of the frontal lobe
superior, middle, & inferior gyri
Inferior Frontal Gyrus
for most people, the left one is of special significance for speech
Contains Broca’s Area (the motor speech area)
Frontal Lobe Impairments
Loss of simple movement, loss of ability to problem solve, mood changes, inability to speak, poor spontaneity, perseveration, personality changes, difficulty sequencing, loss of flexible thinking, inability to focus on a task, changes in social behavior, motor control issues
Temporal Lobe
Lowest 1/3 of the brain; lies just under the temporal bone
Has no natural demarcation between it & occipital lobe
Contains primary auditory cortex & Wernicke’s area
3 important gyri of the temporal lobe
Superior, Middle, & Temporal gyri
Primary Auditory Cortex
Concerned with hearing; Heschl’s gyrus
Area adjacent is called the secondary auditory cortex
Primary Auditory Cortex location
Present in both hemispheres but is typically larger in left than right
Suggestive of left-dominance for receptive language skills
Right Temporal Lobe
less active but may be responsible for nonverbal memory, appreciation of musical experience, & rhythm
Wernicke’s Area location
Posterior 2/3s of the superior temporal gyrus in the left dominant hemisphere; may be up to 7x larger than its homologue in the right hemisphere
Connected to frontal lobe (motor speech area) via the arcuate fasciculus
Wernicke’s Area Function
Vital for comprehension of written & spoken language
Hippocampus
Medial part of the temporal lobe that forms the medial wall of the lateral ventricle
Mediates memory & learning
Overall Temporal Function
Site of auditory reception, interpretation, & AV association; comprehension of spoken & written material as well as processing of semantic/syntactic sounds; music
Temporal Lobe Impairments
Prosopagnosia, not comprhending spoken words, poor selective attention, STM Loss, Interference w/ LTM, increase/decrease in sexual behaviors, inability to categorize, logorrhea, Increased aggressive behaviors
Occipital Lobe
Smallest of the Lobes
Major structures include the primary visual cortex & the secondary visual cortex
Occipital Lobe Impairments
Visual field cuts, inability to locate objects, inability to recognize drawn objects, poor recognition of movement, poor color recognition, visual illusions, decrease in “seeing” objects, word blindness, inability to recognize words, difficulty reading & writing
Parietal Lobe Location
posterior to the frontal lobe
Post-Central Gyrus
Sensory cortex or sensory strip
Primary sensory area controlling & integrating somesthetic sensory impulses
Concerned w/ perception, sensation of touch, pressure, position, position sense, & body awareness
Controls understanding of spatial relations & selective attention
Damage to right post-central gyrus may cause…
left neglect
Important gyri of the parietal lobe
angular gyrus & supramarginal gyrus
Damage to the supramarginal gyrus may result in…
agraphia &/or conduction aphasia
Agraphia
writing problems
Damage to the angular gyrus may result in…
deficits of reading, writing, &/or naming
May also cause TSA or transcortical sensory aphasia
Parietal Lobe Impairments
Inability to attend to I+; alexia, agraphia, inability to recognize words, difficulty with goal-directed movement, dyscalculia, difficulty drawing objects, difficulty knowing L/R, decreased awareness of body parts, poor manipulations of objects, unilateral neglect, inability to focus visual attention, inability to have hand-eye coordination, impaired perception of touch
Cerebral Ventricles
system of cavities deep within the brain that are filled with CSF
Contain the choroid plexus that produces CSF of which totals are 130mL (30mL in the ventricles, 75mL in the spinal system, 25mL in the cranium
How many cerebral ventricles?
total of 4: 2 lateral, 3rd, and 4th ventricles
Turnover of CSF
around 500mL daily from the choroid plexus to the 4th ventricle to subarachnoid space & arachnoid villi
When CSF is blocked or absorption is impaired…
result is hydrocephalus
The CNS’s protective mechanisms
Layer of skin, bones of the skull, & layers of tissue called meninges
CSF as cushion for brain & spinal cord
Spinal cord protected by vertebral column
Brain maintains shape secondary to these supports as gravity would distort structure
SCALP
Provides that outermost protective & includes 5 layers
1st line of defense in protection of bony skull & brain
S: skin; C: connective tissue; A: aponeurosis; L: loose areolar tissue; P: periosteum/pericranium
Meninges
protective layers that cover the brain & spinal cord
Outermost membrane of meninges
Dura Mater (2 layers)
Middle membrane of meninges
Arachnoid (contains blood vessels)
Innermost membrane of meninges
Pia mater (covers the brain)
Space between the Arachnoid & Pia mater
subarachnoid space (CSF)
Cerebrovascular system
Many neurological problems arise from disrupted blood supply to the brain
Major etiologies of neurogenic language d/o’s esp. aphasia are vascular pathologies &/or hemorrhage
Brain depends on blood for nourishment & ability to function
Effects of disrupted blood supply on brain
LOC after 10 seconds of blood interruption
Permanent brain damage after 4-6 minutes
Brain’s weight, blood & O2 use
weights roughly 2% of body weight
receives 17-20% of body’s blood
receives 25% of body’s oxygen
External Carotid Artery
muscles of the face & neck; oral/nasal cavities; skull & dura mater
Internal Carotid Artery
Major blood supplier to the brain
2 Main Branches of the Internal Carotid Artery
Anterior cerebral & middle cerebral arteries
Anterior Cerebral Artery
Supplies the middle portion of the frontal & parietal lobes, basal ganglia, & corpus callosum
Damage to anterior cerebral artery
causes disruption of blood to the midsagittal portions of the motor cortex
Motor symptoms include: paralysis of legs & feet
Associated cognitive deficits: impaired reasoning, judgment, & concentration
Middle Cerebral Artery
Largest branch of internal carotid; supplies blood to entire lateral surface of cortex including major portions of frontal lobe
Supplies somatosensory cortex, motor cortex in precentral gyrus, Broca’s area, primary auditory cortex, Wernicke’s area, angular & supramarginal gyrus; putamen, caudate nucleus, globus pallidus, & portions of thalamus
Damage to middle cerebral artery
frequent result of stroke & aphasia; will cause contralateral hemiplegia
Impaired sense of touch, position sense, pain, & temperature; reading/writing deficits
Vertebral Artery
branches of the 2 subclavian arteries that emerge from aortic arch; left/right join together to form basilar artery
Basilar Artery
Divides to form 2 posterior cerebral arteries
Supplies lower/lateral temporal lobes & middle/lateral portions of occipital lobe
Other branches supplies pons, cerebellum, inner ear
Watershed Areas of Brain
Anterior, middle, & posterior cerebral arteries supply majority of blood to brain; each 1 ends individual distribution & supply in small branches of arteries
What happens if watershed areas are damaged
somewhat inefficient supply of blood
if blood supply to these areas is interrupted, specific kinds of aphasias can result in addition to other vascular diseases
TCS & TCM
