Exam 3: HIGHER ORDER CEREBRAL FUNCTIONS

Question 1

what is the role of the limbic system?

Answer 1

The cognitive production of emotion involves many limbic system structures, the amygdala and the aspects of the frontal lobe

Question 2

how is emotion cortically lateralized?

Answer 2

• The right hemisphere is important for the expression and comprehension of affective aspects of speech. People with damage to the regions involved with emotion in the right hemisphere might display a monotone voice, thought they still feel normal emotion
• The left hemisphere is associated with positive emotions whereas the right hemisphere is associated with negative emotions

A. Incidence and severity of depression is significantly higher in those with left hemisphere damage
B. Right hemisphere lesions tend to produce a person who is unduly cheerful
C. When faces are shown to only one hemisphere or the other, the right hemisphere is better at discriminating emotional facial expressions

Question 3

what is the role of emotion in addiction

Answer 3

The basal ganglia, which we previously talked about in relation to control of movement, also has regions within in that are critical for addiction/emotional reinforcement

Question 4

Addiction: the VTA to NA pathway and role of dopamine

Answer 4

1) The nucleus accumbens (NA) within the basal ganglia contains neurons that receive dopaminergic input from neurons in the ventral tegmental area (VTA) in the midbrain.
2) Drugs of abuse act on this VTA to NA pathway to produce addiction
3) The presence of drugs of abuse leads to dysregulation in the limbic circuitry, including the VTA and NA. Drugs of abuse:
- Increase activity of the
enzyme tyrosine
hydroxylase, which makes
dopamine

Question 5

what are the two types of memory?

Answer 5

Declarative – storage and retrieval of material that is consciously available and can be expressed by language. Examples are autobiographical information, knowing “facts”

Nondeclarative – storage and retrieval that is largely subconscious, often times motor skills like riding a bike or how to use your phone are examples. Thinking about how to do these activities might actually inhibit their performance

Question 6

What areas are important for memory acquisition and storage of memory for each type?

Answer 6

Declarative:
LT: Wernicke, temporal cortex
ST: hippocampus

Nondeclarative:
LT: cerebellum, basal ganglia, premotor cortex
ST: sites unknown, but presumably widespread

Question 7

a. Why did patient HM have to get his temporal lobes removed?
b. What was the result of this surgery?
c. What memory was spared and what was not?

Answer 7

a. Henry Molaison (HM), suffered from severe epilepsy. Because his seizures began in the temporal lobes, a decision was made to remove the anterior temporal lobes on both sides.
b. H.M. had normal working-term memory but had severe anterograde amnesia and could not form long term memories.
c. H.M. was able to show improvement with motor skills but could not remember performing them (i.e. he could not recall the tasks verbally.). This is an issue with declarative memory

Question 8

What is ECT? What is the effect of ECT on memory?

Answer 8

Electroconvulsive therapy (ECT)

1) ECT involves passing electrical current to anesthetized patients as a treatment for various disorders, including depression
2) ECT can cause temporary anterograde and retrograde amnesia. The amnesia generally resolves within a few months

Question 9

How does the brain change with age and what is the effect on memory?

Answer 9

• Brain weight decreases with age, likely due to decreased number of synapses
• Memory function and ability to make associations is affected as a result
• Age-related disorders involving memory include dementia and Alzheimer’s disease

Question 10

What is the overall role of the association cortices?

Answer 10

• Higher order processing within the senses, planning, executive functions, language, emotion and similar processes are all a function of the association cortices
• The association cortices allow you to attend to stimuli, maintain attention, identify significance of stimuli

Question 11

What is distinct about the association cortices?

Answer 11

1) Inputs to the association areas come from other cortical areas as well as the thalamus. The nuclei within the thalamus are distinct than the ones where primary sensory information is sent
2) Input that comes from the thalamus to the association areas has already been processed. Primary sensory and motor areas send projections to the specific thalamic nuclei, which then project to the association areas.
3) The association areas have many interhemispheric (between hemispheres) and corticocortical (between cortex) connections
4) Damage to the association cortices has distinct behavioral outcomes because of its cognitive function

Question 12

Parietal Lobe: What is contralateral neglect syndrome?

Answer 12

• Contralateral neglect syndrome is an inability to attend to objects, even ones own body, in space even though the necessary sensory stimuli and its processing in primary areas is intact. Patient is unaware of deficit
• caused by right hemisphere parietal damage

Question 13

Temporal Lobe: What does damage to the temporal association areas produce?

Answer 13

• Damage to temporal lobe association areas leads to difficulty recognizing, identifying, and naming different categories of objects
• These disorders are called agnosias, but unlike with neglect patients who do not realize something is wrong, patients with agnosia know a stimulus is present but cannot report what it is

Question 14

Temporal Lobe: What is prosopagnosia?

Answer 14

Propsopagnosia is a condition where individuals cannot recognize faces (see Oliver Sacks – The Man who Mistook is wife for a hat)

Question 15

What are the two areas involved in language?

Answer 15

Wernicke’s Area and Broca’s Area

Question 16

What are their specific roles?

Answer 16

• Wernicke’s area in the temporal lobe is what takes the primary auditory cortex information and allows for word recognition
• To produce language sounds, broca’s area in the frontal cortex becomes active
• To hear a word and repeat the word requires both of these areas:
  Wernicke’s allows for word comprehension based on sound and then this information is sent to broca’s area via the arcuate fasciculus and other white matter tracts

Question 17

How do the aphasias produced by damage to Broca’s?

Answer 17

Broca’s Aphasia – occurs as a result of lesions to the frontal lobe Broca’s areas (dominant hemisphere)

1) Individuals with this aphasia have a decreased fluency in spontaneous speech
2) Individuals with Broca’s aphasia have naming difficulties as well

Question 18

How do the aphasias produced by damage to Wernicke’s?

Answer 18

Wernicke’s Aphasia

1) Patients with Wernicke’s have impaired language comprehension
2) Patients will not appropriately answer questions or follow commands; their speech is empty, meaningless and filled with paraphasic errors, which are inappropriate substitutions for words
3) Patients are unaware of their deficit, unlike with Broca’s area

Question 19

Do animals have language?

Answer 19

1) Chimps and cetaceans have homologues to Broca’s and Wernicke’s area, and these areas show a possible asymmetry in the left versus right (with chimps) just like in the human brain (Taglialatela et. al. 2008)
2) However, language is distinct in that it is not a simple vocal response or reaction to immediately-present stimuli (see image on right)
a. As we will see, animals like songbirds and non-human primates have certain aspects of language, but not the full complexity of human language

Question 20

What gene is thought to underlie human language? How is it thought to do this?

Answer 20

1) FOXP2 is a gene found in all mammals (with homologues in birds). In humans, FOXP2 has two point mutations that distinguish it from all other primates and mammals
2) A familial disorder called specific language impairment (SLI) is caused by a mutation in FOXP2, which produces severe issues with pronunciation, fluency, and understanding proper syntax
3) In mice who have damage to one copy of FOXP2: impair ultrasonic vocalization and damage to both copies eliminates them completely. Adding the human variant of FOXP2 to mice produces mice that perform better on certain learning tasks