Lecture 3: Brain Function

Question 1

How many neurons does the cerebral cortex contain?

Answer 1

100 Billion Neurons

Question 2

What are the 3 types of cortical neurons?

Answer 2

> Granular (stellate)
Fusiform
Pyramidal

Question 3

Between fusiform and pyramidal cortical neurons, which one is smaller output neurons and which is large output neurons?

Answer 3

Fusiform -> smaller output neurons.

Pyramidal -> large output neurons.

Question 4

What are the characteristics of granular (stellate) cortical neurons?

Answer 4

> short axons
interneurons
both excitatory (glutamate) and inhibitory (GABA)

Question 5

What function does cerebral cortex layers I, II, and III have?

Answer 5

Intracortical association functions

bring together all signals

Question 6

What function does cerebral cortex layers V and VI have?

Answer 6

> origin of most output signals

> fibers to thalamus from VI

Question 7

What function does the cerebral cortex layer IV have?

Answer 7

> termination of most incoming specific sensory signals

Question 8

Objective 2: describe the functional relationship of the cerebral cortex to the thalamus and brain stem.

Answer 8

Read about the “thalamocortical system” in the book.

Question 9

What do primary motor areas direct?

Answer 9

Direct connections with specific muscles.

Question 10

What does the primary sensory areas detect?

Answer 10

Detect specific sensations.

Question 11

What does the secondary motor areas provide?

Answer 11

Provide patterns of motor activity.

Question 12

What does the secondary sensory areas analyze?

Answer 12

Analyze meanings of specific sensory signals.

Question 13

Which sulcus separates the voluntary motor and somatosensory portions of the brain?

Answer 13

Central Sulcus

Question 14

What is the function of association areas of the brain?

Answer 14

Association areas receive and analyze signals simultaneously from multiple motor and sensory cortices.

Question 15

Name the association areas of the brain.

Answer 15

> Parieto-occipitotemporal association area

> Prefrontal association area

> Wernicke’s area

> Broca’s area

> Limbic association area

Question 16

What are the sub-areas that make-up the parieto-occipitotemporal association area?

Answer 16

> area for analysis of spatial coordinates

> Wernicke’s area

> Angular gyrus area

> Area for naming objects

Question 17

What is the function of the prefrontal association area?

Answer 17

Receives preanalyzed sensory information (esp concerning spatial coordinates) necessary for planning efective movements.

“important in planning motor activity”

Carriers out “thought” processes in the mind

Question 18

Where does the output signal from the prefrontal association area pass through?

Answer 18

Output passes through caudate portion of basal ganglia.

Question 19

True or False:

The Broca’s area and Wernicke’s area do not communicate.

Answer 19

False - the Broca’s area works closely with Wernicke’s area

Question 20

What is Broca’s area function to do? Also, what side of the brain is Broca’s area typically dominant on?

Answer 20

> Provides circuitry for word formation

> Works closely with Wernicke’s area

> Almost always dominant on left side of brain

Question 21

What is the function of the Limbic association area?

Answer 21

> Concerned with behavior, emotions, and motivation

Question 22

What is the Wernicke’s area of the brain?

Answer 22

Language Comprehension

** Area where somatic, visual, and auditory association areas all meet one another in the posterior part of the superior temporal lobe **

** Located on left side in almost all right-handed people **

Question 23

What major role does the Wernicke’s area play?

Answer 23

Wernicke’s area plays the greatest single role of any part of the cerebral cortex for intelligence.

Question 24

What is the activated Wernicke’s area able to do?

Answer 24

Activation of Wernicke’s area may be able to call forth complicated memory patterns involving more than one sensory modality.

Question 25

True or False: The activation of the Wernicke's area may be able to call forth complicated memory patterns involving more than one sensory modality.

Answer 25

True

Question 26

True or False: Some association areas are not bilaterally symmetrical: > Wernicke's area and the angular gyrus are more developed in the left hemisphere in 95% of the population. > Broca's area is almost always dominant in the left hemisphere. > Motor areas for controlling hands are also dominant in the left hemisphere in 90% of people.

Answer 26

TRUE

Question 27

Facial recognition is an important task for to function as a physician. Which two lobes of the brain does the facial recognition area span?

Answer 27

> Occipital - occipital portion of facial recognition area is next to the visual cortex > Temporal - temporal portion is closely associated with the limbic system

Question 28

What does damage to the facial recognition area result in ?

Answer 28

Extensive damage to this area results in prosopagnosia (inability to recognize faces).

Question 29

What are the characteristics of a patient that presents with a prefrontal lobotomy?

Answer 29

> loss of ability to solve complex problems > inability to string together sequential tasks to reach complex goals > inability to do several parallel tasks at the same time > decrease in level of aggressiveness (ambition) > inappropriate social responses > inability to carry through long trains of through > loss of purpose while performing usual motor pattern functions

Question 30

What abilities are attributed to the brain's working memory?

Answer 30

> prognostication > planning for future > delay in response to incoming sensory signals > ability to consider consequences of motor actions > ability to solve complicated mathematical, legal, or philosophical problems > control of activities in accord with moral law

Question 31

What is the main function of the corpus callosum?

Answer 31

> The corpus callosum is the major commissure between the two hemispheres.

Question 32

What happens if the corpus callosum is cut?

Answer 32

> blocking of transfer of information from Wernicke's area to nondominant motor cortex > prevention of the transfer of somatic and visual information from right hemisphere into Wernicke's area > results in two entirely separate conscious portions of the brain

Question 33

When speaking a heard word, is the angular gyrus involved?

Answer 33

NO, only when speaking a written word.

Question 34

Where does the sensory transmission start when speaking a written word?

Answer 34

The occipital lobe.

Question 35

Where does the sensory transmission start when speaking a heard word?

Answer 35

primary auditory area in the temporal lobe

Question 36

What is declarative memory?

Answer 36

Refers to memory of various details of an integrated thought.

Question 37

What is included in declarative memory?

Answer 37

> memory of surroundings > memory to time relationships > memory of causes of experience > memory of meaning of experience > memory of deductions as a result of experience

Question 38

What is reflexive (skill) memory associated with?

Answer 38

Associated with motor activities.

Question 39

What is an example of short-term memory and how long does it last?

Answer 39

> exemplified by memory of a telephone number > lasts only as long as person thinks of number or facts (seconds)

Question 40

How long does intermediate long-term memory last?

Answer 40

> lasts many minutes or weeks > may become long-term memory (more permanent) if memory traces are activated enough

Question 41

What does stimulation of facilitator presynaptic terminal at the same time that sensory terminal is stimulated cause?

Answer 41

Serotonin release at facilitator synapse. *studied in Aplysia (sea snail)*

Question 42

What do serotonin receptors in the sensory terminal membrane of Aplysia activate?

Answer 42

Adenyl cyclase -> cAMP

Question 43

What does the cAMP activate?

Answer 43

potassium channels

Question 44

How long is the potassium channel blocked in the serotonin released sensory pathway in Aplysia?

Answer 44

Potassium channel is blocked for minutes to weeks.

Question 45

What does the blocking of potassium channels in Aplysia cause?

Answer 45

Lack of potassium conductance causes greatly prolonged action potential in synapse terminal. * this prolonged action potential causes prolong activation of calcium channels* * prolonged activation of calcium channels prolongs transmitter release*

Question 46

What structure changes happen in long-term memory?

Answer 46

> increase in vesicle release sites for secretion of transmitter substance > increase in number of transmitter vesicles released > increase in number of presynaptic terminals > changes in structures of the dendritic spines