Studied by 240 peoplefrontal lobe
front of brain
parietal lobe
above occipital lobe
occipital lobe
back of brain, vision
temporal lobe
under the frontal lobe
What are the cerebral hemispheres?
the two halves of the brain
what are the cerebral hemispheres separated by?
longitudinal fissure
What do the cerebral hemispheres do?
Control voluntary movement, interpret sensory information and are responsible for learning and memory
central sulcus
separates frontal and parietal lobes
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
what is the benefit of the corpus callosum?
the communication between the hemispheres allows for faster processing and thinking
Thalamus
the brain's sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and medulla
brain lateralization
The organization of the brain into right and left hemispheres, with each hemisphere performing unique and specialized functions
why is brain lateralization important?
it allows for parallel processing and the redundant systems allow for processing to occur if one hemisphere is damaged
motor system (efferent)
Carries messages from the central nervous system to muscles and glands
cerebral dominance
refers to hemisphere that is dominant for language (usually left hemisphere)
Anterior
front
Posterior
back
superior/dorsal
top
inferior/ventral
bottom
anterior dominant cortex controls...
expressive language (including writing)
posterior dominant cortex controls...
expressive language (including reading)
left hemisphere of brain
controls right side of the body and is logical, contains mathamatics, lauguage, & speech
right hemisphere of brain
plays significant role in prosodic aspects of language
expressive prosody is controlled by...
the non dominant anterior cortex
receptive prosody is controlled by...
the non dominant posterior cortex
language deficits
most commonly produced by focal lesions, but more diffuse lesions can product subtle language deficits in high level language skills such as organization
Broca's area
Anterior structure responsible for ability to speak or write (motor patterns)
Wernicke's area
Posterior structure responsible for auditory images/ Information
Arcuate Fasciculus
fibre track connecting Wernicke's and Broca's areas
Broca's aphasia
o Halting speech and writing o Stroke damage in Broca's area o Non-fluid Agrammatic speech o Communication of language not great
Wernicke's aphasia
o Fluent Aphasia o Echolalia - repetition of words over and over again (severe cases repeat same word) o No complete answers or understanding o Understanding of language is not great
progressive non-fluent aphasia (primary progressive aphasia)
degenerative disease that looks like Broca's (expressive deficits)
early to mid 50's onset
caused by frontotemporal lobar degeneration or frontotemporal dementia
expressive deficits
-Reduced vocabulary -Omission/addition of words -Stereotypic speech -Delayed or reduced output of speech -Hyperfluent speech -Word substitutions
Expressive aphasia (Broca's)
left posterior frontal (Broca's area)
impaired speech
impaired writing
impaired repetition
grossly intact comprehension
grossly intact reading
receptive aphasia (Wernicke's aphasia)
left posterior temporal/parietal (wernicke's area)
fluent, nonsensical speech
Impaired comprehension
impaired reading
grossly intact writing
mildly impaired repetition
Semantic Dementia (SD)
Fluent speech, anomia, impaired comprehension, empty speech, semantic memory network broken, looks like Wernicke's aphasia
Global aphasia
left anterior and posterior
impaired speech
impaired comprehension
impaired reading
impaired writing
impaired repetition
Mixed Transcortical Aphasia
left anterior and posterior, sparing broca's and wernicke's areas
impaired speech
impaired comprehension
impaired reading
impaired writing
intact repetition
Transcortical Motor Aphasia
left anterior frontal, mildly affected Broca's area
impaired speech
typically intact comprehension
typically intact reading
impaired writing
typically intact repetition
Transcortical Sensory Aphasia
posterior parietal/temporal cortical lesion with sparring of wernicke's area
impaired speech
impaired comprehension
impaired reading
typically intact writing
typically intact repetition
Conduction aphasia
lesion of the acute fasciculus which connects broca's and wernicke's area
grossly intact speech
intact comprehension
intact reading comprehension, oral reading poor due to paraphasias
grossly intact writing
severely impaired repetition
Wernicke-Lichtheim Model: Conduction Aphasia
arcuate fasciculus impacted, nothing else
unable to repeat
Wernicke-Lichtheim Model: Wernicke's Aphasia
Auditory images region impacted
Wernicke-Lichtheim Model: Transcortical Sensory Aphasia
damage between Wernicke's and Concept area
able to repeat because arcuate fasciculus is intact
Wernicke-Lichtheim Model: Transcortical Motor Aphasia
damage between concept area and Broca's
able to repeat, can't produce speech
Wernicke-Lichtheim Model: Broca's Aphasia
damage to speech region
What anatomical areas are close to Wernicke's area?
Wernicke's area located in temporal lobe, close to supramarginal gyrus, angular gyrus, primary auditory area
What anatomical areas are close to Broca's area?
Broca's area located in frontal lobe, close to primary motor strip
What is the purpose of redundant, communicating arteries in brain?
To try and avoid catastrophic damage to the tissues
medulla and pons functions
associated with basic life functions
Cerebellum functions
associated with balance, postuire, motor coordination, implicit learning
The frontal lobes are associated with
motor functions, expressive language, "executive" functions (e.g., behavioral planning, monitoring/regulation, inhibition, motivation, judge,ent), and mood/affect (emotional regulation) Also includes olfactory cortex.
parietal lobe function
is associated with somatsensory functions, spatial awareness/attention and complex visuoperceptual processing (reading and shape orientation/direction)
The temporal lobe is associated with:
receptive language, primary auditory cortex, declarative memory, visuoperceptual processing (form/shape integration), mood/affect, and olfactory cortex.
Occipital lobe associated with
o primary and secondary visual processing.
Sylvian fissure (Lateral fissure)
Separates the temporal from the frontal lobe, and the temporal from the parietal lobe
Sulcus
indentations in brain
fissure
large sulcus (indentation)
gyrus (gyri)
rounded elevation on the surface of the cerebral hemispheres
superior temporal gyrus
the large gyrus of the temporal lobe adjacent to the lateral fissure; the location of auditory cortex
anterior cerebral artery
The arteries that supply oxygen to most medial portions of frontal lobes and superior medial parietal lobes; strokes here can affect leg use
anterior communicating artery
connects right and left anterior cerebral arteries
posterior cerebral artery
supplies occipital lobe
middle cerebral artery stem
largest branch of internal carotid artery,
supplies blood to entire lateral cortex.
involved in language because it provides blood to subcortical structures of temporal and frontal lobes
lenticulostriate arteries
small, deep penetrating arteries that branch from the middle cerebral artery, very thin and vulnerable to strokes
language assessment
includes expressive skills, Receptive skills, repetition, prosody
language assessment: expressive skills
fluency -articulation -organization -writing
language assessment: receptive skills
naming
aural comprehension
reading
language assessment: prosody
expressive prosody
receptive prosody
What is the relay center of the brain?
the thalamus
paraphasia
-phonemic -semantic
right hemisphere contributions to language
Good auditory comprehension of language -If left hemisphere removed early, the right hemisphere can acquire language
If left hemisphere removed in adults, severe deficits in speech but still good auditory comprehension -Removal of the right hemisphere produces subtle changes in language comprehension
Hemispherectomy
removal of a hemisphere
Heschel's gyrus
primary auditory cortex, anterior to Wernicke's area in right hemisphere
important for words
right hemisphere damage
unable to process non-verbal sounds
auditory agnosia and amusia
pure word deafness
the ability to hear, to speak, and (usually) to read and write without being able to comprehend the meaning of speech; caused by damage to Wernicke's area or disruption of auditory input to this region
what is the right hemisphere's main contribution in langauge?
prosody
receptive aprosody
associated with lesion in right hemisphere temporoparietal area
patient unable to appreciate tone, inflection and expression of another even in repetition
patient can express inflection, tone, emotion
expressive aprosody
associated with lesion in right hemisphere frontal region, next to left hemisphere's Broca's area
patient can't express inflection and tonal quality of emotion
patient can appreciate another's inflection and tone
memory
encode, retain, retrieve
verbal (lateralized function), non verbal
hierarchical function - requires the basics such as attention and other cognitive components to be intact
sensory registration
auditory, visual, gustatory, tactile, or olfactory information enters -consciously registered, brain deems importance of information very quickly
lasts ms to s
attention required for next step
short-term memory
working memory, but more of an attention system
normal person able to remember 7±2 items in STM
brief system
chunking of information can help
organizing or rehearsal required for next step
long-term memory
includes everything that can be recalled within few minutes
relatively permanent
can be accessed
consolidation process used in LTM
LTM (long term memory) factors
rehearsal
emotional salience: things are easier to remember when there is emotion attached
Levels of encoding: o Elaboration: building new information on top of what is known o State dependent learning: able to recall better when in same internal state as when information was learned o Environmental dependent learning: internal and external cues help with recollection of information
Papez circuit
a circuit of structures interconnecting hippocampus, mamillary bodies, thalamus and cingulate gyrus.
involved in forming new autobiographical memories and declarative memories
stages of memory
sensory storage
no attention = forgetting
attention = STM
STM
processing = LTM
no processing = forgetting
LTM
encoding from STM
explicit memory (declarative memory)
can declare it
contains episodic memory and semantic memory
Verbal-visual
Intentional- incidental
Recent - remote
Frequently disrupted due to many etiologies of disease
episodic memory (part of explicit memory)
truly autobiographical or autobiographically bound o - where you learned it, when you learned it o - retrieval of the learning event
semantic memory (part of explicit memory)
facts
language concept area
not time dependant
Retrieval of a fact
No idea where or when you learned it - it is a fact
implicit memory
Skills and procedures
Origins of learning often lost
Often preserved in disease due to more distributed nature of this neuroanatomically
Why are there more clinical problems associated with declarative memory than non-declarative memory?
Declarative memory involves the medial temporal lobes which are neuroanatomically vulnerable. Non-declarative memory is diffused across many subcortical structures meaning it is harder to damage
anterograde amnesia (AA)
damaged episodic memory due to damage in hippocampus or other regions of papez circuit
inability to form new memories
Cannot learn new information
Most common memory impairment
patient HM: had bilateral resection of hippocampus
retrograde amnesia (RA)
loss of memory for events prior to injury
temporally graded: tend to remember less closer to injury, and more further from memory
rarely spans years
very rare to have RA without AA
can have AA without RA
encoding
the process of getting information into the memory system,
Consolidation
taking encoded information and storing it more permanently, associated with neuroanatomical change in brain making new circuit
retrieval
accessing stored memory, do better with cues than free recall
primacy effect
tendency to remember words at the beginning of a list especially well
recency effect
tendency to remember words at the end of a list especially well
memory assessment focuses on...
immediate: asking for information right away
learning: repeat and test information to see progress
delayed: distract to prevent rehearsal and see consolidation
cued: help to assess retrieval
recognition: help to asses retrieval
memory impairments caused by....
Orbitofrontal and medial frontal structures
Diencephalic lesions
Severe mesial temporal lobe damage
Note
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