77 - Cerebral Cortical Function

Question 1

Which hemisphere of the brain is typically the dominant in terms of language? Which is non-dominant?

Answer 1

Most common

• Right = non-dominant
• Left = dominant

Question 2

What anatomical (not functional) difference is there between the right and left hemispheres?

Answer 2

Anatomical difference: planum temporal is larger in the left hemisphere than in the right in most human brains.

Question 3

Describe the non-dominant hemisphere

Answer 3

• usually right hemisphere
• usually superior in spatial abilities, the comprehension of complicated patterns. Example: 3-dimensional puzzles
• control of affective components of language: prosodic elements

Question 4

What are the functions of non-dominant hemisphere (usually right brain)?

Answer 4

• Analysis of left visual field
• Stereognosis (left hand)
• Emotional coloring of language
• Spatial abilities
• Rudientary speech

Question 5

What are the functions of the dominant hemisphere (usually left brain)?

Answer 5

• Analysis of right visual field
• Stereogosis (right hand)
• Lexical and synatactic language
• Writing
• Speech

Question 6

What is an aphasia?

Answer 6

Aphasia: acquired disorder of language due to brain damage

Question 7

Describe Broca’s aphasia

Answer 7

• classified as a nonfluent aphasia
• Patient has limited speech but it is slow and labored with nonessential words omitted (telegraphic speech)
• Patient can comprehend single words and grammatically simple sentences.
• Impaired repetition
• Patients are aware of their language difficulties and very frustrated and upset by it.

Question 8

What causes Broca’s aphasia?

Answer 8

• Caused by lesions in Brodmann areas 44 and 45 in milder Broca’s area aphasia. Broca’s aphasia is caused by more extensive damage that includes additional areas surrounding and deep to Broca’s area (including insula cortex and part of the basal ganglia).

Question 9

Describe Wernicke’s aphasia

Answer 9

• Patient with severe form of Wernicke’s aphasia cannot understand either spoken or written language but they display fluent paraphasic speech. Speech sometimes called word salad.
• Less severely affected patients use many paraphasias; patient may use an incorrect but similar sounding word.
• Patients with Wernicke’s aphasia seem much less aware of their problems than patients with Broca’s aphasia.

Question 10

What causes Wernicke’s aphasia?

Answer 10

Usually caused in part by lesions in Brodmann area 22 in the posterior part of the temporal gyrus . Patients with Wernicke’s aphasia can also have damage in area 37, 39 and 40 so not just caused by damage to the temporal lobe.

Question 11

What is conduction aphasia?

Answer 11

Comprehension can be normal for simple sentences and speech is fluent but patient uses many paraphasias. Ability to repeat what is heard is lost.

Question 12

What causes conduction aphasia?

Answer 12

Caused by interruption of the connections between Broca’s and Wernicke’s areas. Damage is to complex connection system not just the arcuate fasciculus.

Question 13

What is global aphasia?

Answer 13

• Most severe form of aphasia
• Patients cannot produce understandable speech or comprehend spoken language or written language.
• May still have “automatic” speech such as stock expletives, and reciting days of the week or counting. Some patients can sing previously learned songs including melody and lyrics

Question 14

What causes global aphasia?

Answer 14

Global aphasia may often be seen immediately after the patient has suffered a stroke and it may rapidly improve if the damage has not been too extensive. However, with greater brain damage, severe and lasting disability may result.

Question 15

What causes neglect syndrome

Answer 15

• Damage to posterior parietal lobe in non-dominant hemisphere (usually right hemisphere) causes neglect syndrome
• Contralateral neglect syndrome is broken down into different kinds of neglect

Question 16

What is personal neglect syndrome?

Answer 16

Occurs with damage to right hemisphere
• deficit in self-image of left side of body
• patients might not wash or dress affected side
• patients might deny left arm or leg is part of them

Question 17

What is spatial neglect?

Answer 17

• sensory neglect of extra personal space on one side

* problem copying left side of drawing

Question 18

What is representational neglect?

Answer 18

• neglect of one half of a remembered image

* evidence memory for extra personal space is stored with a body-centered frame of reference

Question 19

What do we know about neglect from parietal lobe damage?

Answer 19

Neglect from parietal lobe damage consistent with many studies showing that the parietal lobe contains attention sensitive neurons.

Question 20

What is asomatognosis?

Answer 20

When patient has lack of awareness of the condition of all or part of his body

Verbal asomatognosia is when patient verbally denies for example that his arm belongs to him

Question 21

What is asterognosis?

Answer 21

a. inability to identify objects by feeling them
b. can be caused by lesions in somatosensory cortices in parietal lobe
c. Agnosia-is general term for the inability to recognize objects by a particular sensory modality even though sensory modality itself is intact.

Question 22

What is affective language?

Answer 22

The components of language that express emotion

Prosodic elements

i. Emotional voice quality/intonation of speech
ii. Emotional gesturing

Question 23

What hemisphere is responsible for affective components of language

Answer 23

Under control by “non-dominant” hemisphere (typically right)

Question 24

Who was a famous patient with prefrontal lobe syndrome?

Answer 24

Phineas P. Gage was a famous patient with frontal lobe damage

Question 25

What are the three kinds of prefrontal dysfunction?

Answer 25

Based on the area affected - dorsolateral prefrontal area - orbitofrontal area - medial frontal/anterior cingulate area

Question 26

Describe damage to the dorsolateral prefrontal area

Answer 26

Patients have trouble with executive functions; planning, choosing goals, monitoring the execution of a plan. They do very poorly on Wisconsin Card sorting task, tendency to perseverate.

Question 27

Describe damage to the orbitofrontal area

Answer 27

Patients have disinhibition; they ignore social conventions, are impulsive and unconcerned about consequences.

Question 28

Describe damage to the medial frontal/anterior cingulate area

Answer 28

Patients display apathy and slowing of cognition. This apathy can cause abulia or even akinetic mutism.

Question 29

What is abulia?

Answer 29

Abulia is the loss or impairment of the ability to perform voluntary actions and make decisions.

Question 30

What is akinetic mutism?

Answer 30

patient does not move or speak even though they are awake.

Question 31

What are frontal release signs?

Answer 31

release of “primitive” reflexes examples-suckling reflex, grasp reflex, these sometimes called frontal release signs.

Question 32

What is preservation?

Answer 32

Tendency to continue with one form of behavior when situation would require new, changed response

Question 33

Describe the features of prefrontal syndrome

Answer 33

1. personality changes including loss of a sense of social propriety and sense of responsibility 2. planning deficits 3. perseveration- tendency to continue with one form of behavior when situation would require new, changed response 4. release of “primitive” reflexes examples-suckling reflex, grasp reflex, these sometimes called frontal release signs. 5. lack of ambition 6. akinetic mutism-patient can become motionless and mute even though patient could move and talk if he “wanted” to. Patient is profoundly apathetic. Patient can be less severely affected showing a lesser decrease in will or motivation (abulia).