Is language controlled by both hemispheres equally or unequally? If unequally, which is more important?
The left hemisphere is mostly in charge of language.
It was found that patients with language deficits (aphasias) had damage to ____?
It was found that patients with language deficits (aphasias) had damage to the left hemisphere
Where is Broca's area?
Small area in left inferior prefrontal cortex
(nearish primary motor cortex and articulation areas)
What is Broca's aphasia?
Problem with speech production: expressive aphasia
- Normal comprehension, speech is meaningful... but awkward (comprehension fine; output damaged)
- Can't express self, either verbally, written, or via sign language
What artery supplies Broca's area?
Middle cerebral artery (posterior)
- Could also result from tumors or strokes
How does Broca's aphasia affect the mouth/articulatory systems?
Nothing is wrong with the mouth or articulatory systems; it is NOT apraxia
Where is Wernicke's area?
Just posterior to primary auditory cortex
(superior temporal gyrus)
What is Wernicke's aphasia?
- Reduced language comprehension (can't understand others or self)
- Reduced ability to produce intelligible speech
- Speech sounds normal but has no meaning: 'word salad', jargon, neologisms, logorrhea, uninhibited output
- "Lost in a fog of sounds, words, and references that mean nothing"
- Can't name objects
- Affects all language (NOT an apraxia), written output is also impaired, and a deaf pt makes gibberish sign language
- Pts who recover report that while aphasic, they found the speech of others to be unintelligible and, despite being cognizant of that fact that they were speaking, they could neither stop themselves nor understand their own words (can still detect intonation, sarcasm, humor, but not meaning)
T/F: Broca's affects all language
T/F: Wernicke's affects all language
True: Broca's affects all language
True: Wernicke's affects all language
Which patient suffers more: Broca's or Wernicke's aphasia?
- Broca's patient realizes impairment and suffers from it; often depressed
- Wernicke's aphasics usually do not understand why people aren't understanding them
Affected areas of brain in Broca's vs. Wernicke's aphasia (picture)
What connects Wernicke's and Broca's area?
What is conduction aphasia? What would you observe?
The arcuate fasciculus connects Wernicke's and Broca's areas
- Comprehension and speech normal, but unable to repeat
What is global aphasia? What causes it?
All the disability of Broca's, Wernicke's, and conduction aphasias combined:
- Cannot speak
- Cannot comprehend
- Cannot repeat
Typically caused by infarct of middle cerebral artery
What is alexia?
Inability to read
What is agraphia?
Inability to write
Damage where causes inability to read or write (alexia/agraphia)?
Left angular gyrus (nearer visual system)
Goes to Broca's area still for comprehension
Picture comparing language input for heard/read words and pathway to output
How is hemisphere dominance determined?
Wada test (sodium amytal)
- Anesthetize one hemisphere with barbiturates in carotid and check for language function
Functional brain imaging
- Use fMRI to see which half is active when doing a language test
Which hemisphere is normally dominant? How does this change for right vs. left-handed people?
Left- hemisphere is dominant in almost all right-handers and most left-handers
What is the right hemisphere in charge of language-wise?
Understanding musicality; also inflection and sarcasm...
What does the frontal cortex control?
Damage results in what?
- Intentionality, purposefulness, complex decision making
- Damage -> loss of self, mind, judgment, social interaction, executive control
- Leadership/executive control (only necessary when an organization reaches a certain size and complexity; provides balance and decides when to grant autonomy) (as opposed to damage of posterior brain where damage leads to loss of sensation or movement functionality)
What are the three divisions of the frontal lobe?
Where are they located?
Primary motor cortex (precentral gyrus)
Premotor cortex (anterior to primary cortex)
What does a lesion to the primary motor cortex cause?
Weakness and paralysis of contralateral muscles
What does a lesion to the premotor cortex cause?
Difficulty in producing coordinated movements
What does a lesion to the prefrontal cortex?
Impaired ability to execute plans
What can cause damage to frontal lobes?
- Anterior cerebral artery stroke
- Frontotemporal degeneration (e.g. Pick's disease)
What are symptoms of people with frontal lobe damage?
- Cognition disintegrates and ultimately collapses with frontal lobe damage, like a leaderless army
- Superficial appearance of normality
- Inability to coordinate mental functions taking unseen goals into account
- Disinhibition and lack of behavioral control (impulsive, quick to anger, rude comments)
- Emotional impairments (reduced ability to recognize others' emotional states; irritable, aggressive, alteration of patient's moods and emotions)
- Difficulty planning and organizing their lives
- Impaired working memory (delayed response task impairments)
Are these decisions impeded by frontal dysfunction:
1) If I have $100 in my pocket and loan you $30, how much do I have left?
2) Should I dress as a hippie, zombie, or a superhero for Halloween?
Only 2) is impeded
What are the main parts of the prefrontal cortex (PFC)?
What is the dorsolateral PFC in charge of?
- Working memory
- Holding and manipulating objects
- Impersonal problems
What is the ventromedial/orbitofrontal PFC in charge of?
- Decision making affected
- Moral judgments affected Orbitofrontal
- Required for putting aside attractive things to further a longer term strategy (e.g. suppressing urge to grab/eat food; children have a hard time with such suppression in part due to slow maturation of frontal lobe)
- Connection, meaning
What is seen with people with dorsolateral PFC damage?
Damage -> undermines ability to monitor own performance and to learn from mistakes
Dorsolateral syndrome -> "inertia"
- Pt cannot stop
- e.g. Wisconsin card sorting task: unable to change ways, even when old ways fail to bring reward
What is seen with people with orbitofrontal PFC damage?
Damage -> environmental dependency syndrome
- When confronted by some cue that affords something, they cannot resist
- e.g. see a hammer and nail, cannot help but use it or crawl into bed if sheets are turned down
What part of the brain was damaged in Phineas Gage?
How did this affect him?
- He became unable to follow through with plans
What is Orbitofrontal Syndrome?
- Oscillate between euphoria and rage
- No foresight into the consequence of their actions
- "Not immoral, but amoral"
- Men with orbito-frontal damage often have changes in sexual behavior (e.g. from loveable/gentle to sexual, over-forceful pest who won't take no for an answer)
Irresponsible with money
- Selfish, boastful, puerile, profane, sexually explicit
- Like a drunken adolescent
Formerly "pseudopsychopathic" syndrome
Where is the ventromedial PFC compared to the orbitofrontal?
Ventromedial is just superior to orbitofrontal
What is the ventromedial PFC in charge of?
- Connection, meaning
- Decision making
Lowered activity in the ventromedial PFC causes what? Higher activity?
Lower -> depression (events are fragmented, making all meaningless)
Higher -> mania, paranoia (have in common increased connectivity between everything)
What does this patient have?
- Left frontal lobe shrunken, right missing
- Monstrous social behavior
- Complete absence of anxiety, incapacity for insight, inability to learn from punishment
- “an unawareness of his total life situation involving todays and tomorrows”
- In and out of prisons and psychiatric hospitals
- “a very simplified human organism with only rudimentary mechanisms for social adjustment”
Widespread prefrontal cortex (PFC) damage
What does this patient have?
- "The case of the sudden pedophile"
- 40 yo man, normal sexual appetite
- Increasing interest in pedophilia
Massive frontal lobe tumor
- When tumor was removed, sexual behavior returned to normal
What does this picture show?
What symptoms are expected?
Frontotemporal lobar degeneration
Three clinical syndromes:
- Frontotemporal dementia
- Semantic dementia
- Progressive nonfluent aphasia
Frontotemporal lobe degeneration is the ___ most common cause of dementia in people > 65 yo? In people younger than 65 yo, FTLD is the ___ MCC of dementai?
Frontotemporal lobe degeneration is the 4th most common cause of dementia in those over 65, and the 2nd most common cause in people under 65
What is seen in frontotemporal dementia?
- Disinhibition + diminished emotional concern for consequences
- Sociopathic behavior in 57% of FTLD pts (unsolicited sexual acts, traffic violations, physical assaults, other unacceptable behaviors)
- Aware of their behavior and knew it was wrong but could not prevent impulsive acting
- Claimed subsequent remorse, but did not act on it or show concern for the consequences
In the eyes of the law, responsibility parallels ______?
In the eyes of the law, responsibility parallels volitional control
(Can get in trouble from vomiting in public [but not if food poisoning], crashing a car [but not if epileptic seizure], shouting profanities [but not in Tourette's])