Language and Disconnect Syndromes: Gondre-Lewis

Question 1

Review of the Neocortical Structure

Answer 1

the layers connect different cells to different parts

-Each layer has a distinctive pattern of connections

Question 2

Where do thalamic inputs primarily go to?

Answer 2

layer IV of primary cortex

Question 3

Outputs to subcortical structures come from where?

Answer 3

pyramidal cells in layer V

Question 4

Outputs to other cortical areas come from where?

Answer 4

layer III

Question 5

Layers II and III are for what?

Answer 5

intra and inter hemispheric connections

Question 6

What is area 22? 39 and 40?

Answer 6

Wernicke’s area (in temporal and parietal lobe)

on the left hemisphere

Question 7

What is area 44 and 45?

Answer 7

Broca’s area (in frontal lobe)

Question 8

Primary sensory and motor areas get major input from where? Where does the output of the primary area go to?

Answer 8

Primary sensory and motor areas get major input from thalamic relay nuclei.

The output of the primary area is primarily to association cortex.

These association cortex areas help us to make sense of the sensory and motor input.

As processing progresses, association areas may be multimodal.

Question 9

What is important about the superior longitudinal fasciculus association fibers?

Answer 9

• part of it is a group of axons called the arcuate fasciculus
• those are axon bundles that connects the Wernicke’s to Broca’s area

Question 10

Layer 3 in right brain communicating with layer 3 in left brain is achieved through what type of fibers?

Answer 10

commissural fibers

Question 11

What is very involved in terms of transmitting information from your less dominant side to your dominant language area?

Answer 11

corpus callosum

Question 12

What are the functional regions of the corpus callosum?

Answer 12

splenium: connects the visual cortices to one another
- auditory region is in front of the splenium
- postcentral gyrus region in front of auditory region
- precentral gyrus in front of postcentral gyrus

anterior commissure is responsible for connecting the left and right temporal, hippocampal, and olfactory sides;

these are all involved in the expression of language from these several modalities

Question 13

What is the lateralization of Broca’s and Wernicke’s?

Answer 13

• they do not have counterparts on the right side of brain; only found in the left side of brain
• they are different functions of the equivalent region on the right side

Question 14

What is the splenium of the corpus callosum responsible for in terms of interhemispheric connections?

Answer 14

occipital lobe, areas of 17/18 representing vertical midline

Question 15

What is the posterior body of the corpus callosum responsible for in terms of interhemispheric connections?

Answer 15

posterior temporal lobes (including auditory)

Question 16

What is the mid body of the corpus callosum responsible for in terms of interhemispheric connections?

Answer 16

Primary somatosensory cortex, except for hand and foot areas

postcentral gyrus

Question 17

What is the anterior body of the corpus callosum responsible for in terms of interhemispheric connections?

Answer 17

Primary and association motor areas, except for hands and feet

(precentral gyrus)

Question 18

What is the genu of the corpus callosum responsible for in terms of interhemispheric connections?

Answer 18

rostral frontal lobe

Question 19

What is the anterior commissure responsible for in terms of interhemispheric connections?

Answer 19

anterior and inferior temporal lobes (olfactory)

Question 20

What are functions that are lateralized in the brain?

Answer 20

language: a system of arbitrary symbols, sounds or gestures used for communication, and the grammatical rules used to manipulate them.
praxis: fine motor functions in terms of expression

attention

lateralization meaning there is no contralateral counterpart

Question 21

What is the difference between language and speech?

Answer 21

language: a system of arbitrary symbols, sounds, or gestures used for communication, and the grammatical rules used to manipulate them
speech: mechanical process required for vocalization

Question 22

What is dysarthria?

Answer 22

impaired speech due to muscular problems

muscles in Brocas still have capability to move

Question 23

What is aphasia?

Answer 23

disorder in the reception or expression of language, although sensory and motor systems are intact

inability to express oneself in their language

you know what you want to say but you can’t get the words ti say them or express yourself (nto a physical problem with your lips)

Question 24

What is paraphasia?

Answer 24

incorrect use of grammar

Question 25

What is alexia?

Answer 25

• inability to read

- inability to comprehend writing, although vision is intact.

Question 26

What is agraphia?

Answer 26

inability to write, although motor systems are intact

Question 27

Damage to Broca’s area produces Broca’s aphasia which is what?

Answer 27

motor or expressive aphasia; impaired ability to produce language

Patient IS aware of deficit and is frustrated.

Repetition is poor because of poor fluency and inability to use function words.

Individuals with this aphasia can use nouns and verbs haltingly but not articles, pronouns, conjunctions (function words)

No difficulty in comprehension of language unless there is complicated grammar

Question 28

Damage to Wernicke’s area produces Wernicke’s aphasia which is what?

Answer 28

sensory or receptive aphasia; impaired ability to understand spoken language

Patients have difficulty in comprehending spoken language.

Cannot carry out simple commands. Cannot repeat.

Speech sounds fluent and grammatical, but doesn’t make sense.

Writing is also garbled.

Patient is UNAWARE of deficit, and may be hostile.

Question 29

What area is lesioned for Broca’s aphasia?

Answer 29

area 44 and surrounding areas supplied by the upper division of middle cerebral artery: surrounding cortex and underlying white matter

Question 30

What area is lesioned for Wernicke’s aphasia?

Answer 30

area 22 but also surrounding areas supplied by the middle temporal branch of the middle cerebral artery

larger lesion extending posteriorly into angular gyrus will affect reading as well

Question 31

What is the major artery that impacts language?

Answer 31

middle cerebral artery

Question 32

What is global aphasia?

Answer 32

a blockage of the ENTIRE middle cerebral artery

you cannot understand, produce, or repeat speech

Question 33

Which division of middle cerebral artery supplies Broca’s?

Answer 33

superior division

if lesioned would result in a motor aphasia

Question 34

Which division of middle cerebral artery supplies Wernicke’s?

Answer 34

inferior division

if lesioned would result in a sensory aphasia

Question 35

If the left middle cerebral artery is blocked, but the territories of the middle cerebral artery is more than just language. Can you hear still?

Answer 35

you have bilateral projections you can hear from the right side of brain

you cannot speak what you hear because the info needs to cross over and be represented in the language area on your dominant side

Question 36

If you have hypoxia or some sort of cardiac insufficiency what would be impacted? What is transcortical aphasia?

Answer 36

prolonged hypoxia of watershed regions leaves language areas intact but isolated from the rest of the cortex

isolation of speech areas due to a lack of blood flow to watershed regions

you cannot connect with other parts of the cortex

no spontaneous speech; patient can only repeat, echo-lik, what has been spoken

Question 37

Arcuate fasciculus is part of what fasciculus?

Answer 37

longitudinal fasciculus

Arcuate fasciculus is located deep to the gray matter

Question 38

What is conduction aphasia?

Answer 38

normal fluency, normal comprehension, but repetition is impaired due to lesion of arcuate fasciculus

Repetition: Poor, because the direct, fast pathway between comprehension (Wernicke’s and speech production (Broca’s) is severed. Nevertheless, patients can substitute for this deficit by substituting for the repeated word long descriptions of it.

flour: the item you use to make cakes fluffy

not due to blood flow problem but rather tumor or trauma compressing on the fiber bundle, etc., because it is not like a localized defect around the watershed region

Question 39

What are symptoms of pure word deafness?

Answer 39

patient can read and write normally, produce normal speech, but cannot understand or repeat spoken language

Question 40

Lesions of what can produce pure word deafness?

Answer 40

destruction of auditory association cortex (planum temporale—junction between temporal and parietal lobe) and white matter underlying it, which would carry callosal fibers from non-dominant side

planum temporale is a fiber bundle connecting the primary auditory area with the rest of the parietal areas

Your communication of what you heard onto Wernicke’s area to make sense of speech is impaired

Question 41

If there is unilateral damage to the transverse temporal gyrus (Heschl’s gyrus, primary auditory cortex), would there be a deficit?

Answer 41

you would not have pure word deafness
because you would be able to hear (because contralateral is working) and you would be able to process it as language (because planum temporale is intact–it’s just unilateral damage)

Question 42

What is the function of the non-dominant hemisphere?

Answer 42

• even though it doesn’t process language it is responsible for intonation prosody
• involved in the coloring and emotional language
• it cannot speak but can read and understand numbers, letters, and short words, as long as the required response is nonverbal

Question 43

What would result from lesion to the non-dominant language hemisphere?

Answer 43

result in the loss of prosody: the normal rhythm, stress, and tonal variation of speech; emotional tone

(think of the many ways “I am” could be interpreted through different tones)

Question 44

What is praxis?

Answer 44

skilled motor formulation

Question 45

Which side is responsible for praxis?

Answer 45

the dominant hemisphere parietal lobe because there are extensive connections with the premotor cortex on the contralateral side

Question 46

What results from damage to the dominant hemisphere parietal lobe?

Answer 46

bilateral apraxia

the patient cannot follow instructions if the dominant side is impacted

Question 47

How do you test for apraxia?

Answer 47

ask the patient to carry out an imaginary action, such as saluting the flag, or lighting and blowing out a match

although the patient has intact motor skills, and can perform the action spontaneously, he cannot do so in response to instruction

Question 48

Which side controls attention?

Answer 48

attention is controlled by your nondominant area (usually right) and will produce a contralateral projection

non-dominant hemisphere parietal lobe directs attention to both sides

Question 49

What occurs with lesions to the non-dominant hemisphere in regards to attention?

Answer 49

damage to this area produces contralateral neglect syndrome: inability to attend to objects, or even one’s own body, in a portion of space

Question 50

What results from lesions to the corpus callosum in regards to language areas?

Answer 50

speech and language areas (primarily in the left hemisphere) impacted as a result of disconnection of the axons from one hemisphere to another (corpus callosum)

the patient is able to pick out the named object only using touch but they cannot see the object

the object in the left visual field is sent to the right visual cortex, however information cannot be relayed to the left visual cortex due to section of the corpus callosum and thus cannot be sent to Broca’s area thereafter and thus patient cannot say “I’m picking up the ball.” instead they say “I don’t see anything.”

the right side of the brain is controlling the left hand

Question 51

What could one do to the corpus callosum to alleviate epilepsy?

Answer 51

there can be surgical sections of the corpus callosum to control epilepsy

Question 52

What occurs with lesions to the left visual cortex and parts of the splenium?

Answer 52

you have contralateral hemianopsia

you cannot see because the visual cortex is impacted

you cannot read as well because even though you can see in the left visual cortex, reading needs to cross over to the dominant side

but you can write because the parts of the brain that connect the motor regions are fine

Question 53

What occurs with lesion of the dominant occipital cortex extending to the splenium of the corpus callosum, usually from an infarct of the posterior cerebral artery?

Answer 53

alexia without agraphia

Produces right hemianopia, but also inability to read, since information from the left visual field, thus right visual cortex cannot cross to the language centers due to lesion in the left visual cortex.

Question 54

What happens if the splenium is damaged?

Answer 54

hemialexia of the left visual field

not blind

you cannot read on one side (you have hemi-alexia of the left visual field)

you’re right visual cortex cannot send information to your left visual cortex to send to your language area in the left hemisphere due to damaged splenium

only splenium is damaged, so patient cannot read in the left visual field

your right visual field recorded on your left visual cortex can still talk to your language areas on your left

Question 55

What occurs with lesions to the pre-motor areas of the dominant hemisphere?

Answer 55

the corpus callosum fibers to the opposite hemisphere is impacted and thus would cause dysfunction of the right hand but also cause apraxia of the left hand because praxia is located in the dominant (left) hemisphere

Question 56

Where are the language areas located?

Answer 56

• Located on left in 95% of right-handers and 70% of left-handers.
• Since 90% of people are right-handed, left hemisphere is dominant for 93%.
• Left-handers only may sometimes have bilateral representation.
• Also used for early sign language or second language, though later-learned languages are segregated.

Question 57

There is LATERALIZATION of what functions in the brain?

Answer 57

praxia, attention, language

Question 58

What is the result of lesions to the corpus callosum specifically in the connections between pre-motor areas and not in the premotor areas themselves?

Answer 58

apraxia of the left hand but right hand is normal

left hand is controlled by the right brain but the right hand is controlled by the left hand

Question 59

Lesions to the body of the corpus callosum can result in patients not being able to name objects held in the left hand, but can draw or select that object from a group. Why?

Answer 59

• the body of the corpus callosum disconnects somatosensory cortex from speech areas thus resulting in tactile aphasia of left hand
• you will be able to feel what it is but you cannot say what it is