H4 Neural control of behavior

Question 1

Wat is een zenuw?

Answer 1

Een bundel van de axonen van neuonen in het perifere zenuwstelsel

Question 2

What are the 3 types of neurons?

Answer 2

1. Motor neurons: from CNS to operate muscles and glands
2. Sensory neurons: info from sensory organs into CNS
3. Interneurons: only in CNS, info from one neuron to another. Vastly outnumber other 2.

Question 3

What are the main 3 parts of neurons and their functions?

Answer 3

1. Cell body: nucleus
2. Axon with axon terminal: gives info to other cells. Some are surrounded by a casing called myelin sheath.
3. Dendrite: receives info from other cells

Question 4

What cells produce myelin?

Answer 4

Glial cells

Question 5

What are action potentials?

Answer 5

All-or-none impulses fired off by neurons to influence other neurons. No partial action potentials or different sizes or gradiations. However neuron can vary its rate of action potentials and thereby varying intensity.

Question 6

How does the resting potential arise from the distribution of ions across the cell membrane?
What is the voltage?
Are K+ en Na+ open or closed?

Answer 6

Outside: positive charge, mainly sodium Na+ (also Cl-)
Inside negative charge, mainly A- (protein molecules) (also potassium K+)
70mV

Potassium K+ channels stay open during rest.
Sodium channels Na+ are closed during rest. Open during action potential.

Binnen neuron: elektrisch proces
Buiten neuron: chemisch proces

Question 7

How do the two phases of the action potential (depolarization and repolarization) result from the successive opening and closing of two kinds of channels in the cell membrane?

Answer 7

Depolarization: sodium (Na+) channels open > Na+ moves inside > cell inside becomes positively charged compared to outside.

Polarization: potassium (K+) moves outside (K+ channels are always open) + sodium=potassium pump continuously moves sodium out of the cell and potassium into it > back to original resting state

Question 8

How is an axon’s conduction speed related to its diameter and to the presence or absence of a myelin sheath?

Answer 8

The larger the diameter, the faster the conduction.

Myelin: increases speed. Starts before birth.

Question 9

Where do action potentials start on sensory neurons vs motor neurons?

Answer 9

Sensory: dendrites
Motor: axon at its junction with cell body

Question 10

How do neurotransmitters at excitatory and inhibitory synapses affect the rate at which action potentials are produced in the postsynaptic neuron?

Answer 10

Action potential reaches axon terminal > vesicles spill neurotansmitters in synaptic cleft > vesicles bind to postsynaptic membrane. And then…

At an excitatory synapse: sodium Na+ channels open in postsynaptic membrane > depolarization of receiving neuron > increase rate of action potentials

At an inhibitory synapse: Cl- or K- channels open in postsynaptic membrane > hyperpolarization of receiving neuron > decrease rate action potentials

Question 11

What are 4 ways to deactivate the neurotransmitter effect in synapse?

Answer 11

1. Reuptake by pesynaptic cell
2. Enzymes break down neurotransmitters
3. Uptake by glial cells
4. Diffusion

Question 12

When are most neurons born and when do they begin to fom synapses?
When does synaptic pruning and cell death start?

Answer 12

Neurogenesis and synaptogenesis begin penatally and newborns have more neurons in their brains than adults.
Synaptic pruning and selective cell death of neurons begins prenatally and continues afterr birth.

Birth neurons: First 20 weeks of conception. Peak during 3rd and 4th month after conception. Migration when they start to differentiate. Neurogenesis continues after birth, in particular in hippocampus.

Before birth. Peak of synapse formation varies for different parts of the brain. Fastest in first months after birth.

Question 13

How come brains become bigger after birth?

Answer 13

Neurons become bigger in size and myelination of axons. Not due to generation of new neurons.

Question 14

What percentage of neurons will die or pruned?

Answer 14

40-50% due to synaptic pruning and cell death

Question 15

What are mirror neurons?

Answer 15

Neurons that seem to be designed to foster social learning. They are active when subject engages in a behavior or when subject observes someone else perform a similar action. Function is not reproduction of behavior, but recognize when behavior matches.
They may allow you to understand another’s intentions

Question 16

How (name methods) do researchers identify functions of areas of the human brain through (a) studying the effects of brain damage, (b) using a magnetic field to interrupt normal brrain activity and (c) recording electrical activity that passes through the skull and scalp and (d) creating images that depict patterns of blood flow?

Answer 16

a. brain lesions (electrical (stereotaxic instrument) or chemical (via cannula))
b. TMS, tDCS
c. EEG (event-related potentials (ERP) = brief change in EEG record following stimulus)
d. fMRI, PET

Question 17

What does TMS do?

Answer 17

Repetitive pulses casuse a temporary loss in those neurons’ abilities to fire normally

Question 18

In what directions are the sensory-perceptual and the motor-control hierarchies?

Answer 18

Sensory: bottom up
Motor: top down

Question 19

What are cranial vs spinal nerves?

Answer 19

Cranial: project from brain (12 pairs)
Spinal: project from spinal cord (31 pairs)

Question 20

Definition somatosensation

Answer 20

Set of sensations that derive from whole body as opposed to just from special sensory organs of the head

Question 21

How do autonomic and somatic motor systems differ from one another in function? How do the sympathetic and parasympathetic divisions of the autonomic system differ from one another in function?

Answer 21

Autonomic: visceral muscles + modulate activity
Somatic: skeletel muscles + initiate activity

Sympathetic: prepares body for fight and flight
Parasympathetic: regenerate, growth pomoting, energy conseving

Question 22

3 functions spinal cord

Answer 22

1. Simple reflexes
2. Pathways to and from the brain
3. Pattern generators for locomotion: networks that activate motor neurons in the spinal cord in such a way as to produce the rhythmic sequence of muscle movements that results in walking, running, flying etc

Question 23

How is the brainstem similar and different from the spinal cord? What role does the brainstem play in the control of behavior?

Answer 23

Similar:

• ascending (sensory) and decending (motor) tracts
• neural centers that organize reflexes and certain species typical behavior patterns

Different: entry spinal nerves vs entry cranial nerves

Role brainstem: organize species typical patterns of movement without delibarate decisions to move or refrain from moving in accordance with animal’s longterm interests/needs

Question 24

What are the functional similarities and differences between the cerebellum and the basal ganglia?

Answer 24

Similar: person’s ability to produce learned, skilled, well coordinated movements

Different:
Cerebellum: rapid, well timed sequences of muscle movement, feed forward sensory info/planning
Basal ganglia: slower, deliberate movements, feedback to sensory info/correction

Question 25

What is the organization from top to bottom of brainstem?

Answer 25

Thalamus, midbrain, pons (complex reflexes), medulla (complex reflexes), spinal cord

Question 26

3 Main functions thalamus

Answer 26

1. Relay messages from sensory tracts to brain
2. Relay messages from higher parts of brain to movement control centers in brainstem
3. Relay messages from arousal pathways in midbrain to all areas cerebral cortex

Question 27

Why is the limbic system so named an what are the 2 functions?

Answer 27

Limbus=border. Border in between older and newer parts brain. Hypothalamus is not part of it, but connected with it.

1. Regulation of basic drives and emotions (amygdala)
2. Spatial location and encoding memories (hippocampus)

Question 28

What are the 3 pathways by which the hypothalamus controls the body’s internal environment?

Answer 28

1. Influencing activity autonomic nervous system
2. Controlling release hormones from hypofyse (pituitary gland)
3. Affecting certain drive states such as hunger and thirst

Question 29

What are the four lobes of the cortex and what are the three functional categories of areas within the lobes?

Answer 29

1. Occipital
2. Temporal
3. Parietal
4. Frontal
5. Sensory, primary somatosensory areas in parietal lobe: Receive signals from sensory nerves and tacts by way of relay nuclei in the thalamus
6. Motor, primary motor areas in frontal lobe: Sends axons down to motor neurons in brainstem and spinal cord
7. Association areas: receive input from the sensory areas and lower parts of the brain and are involved in the complex processes that we call perception, thought and decision making

Question 30

What is the principle of topographic organization?

Answer 30

Primary sensory and motor areas of the cortex are organized in such a way that adjacent neurons receive signals from or send signals to adjacent portions of the sensory or muscular tissue to which they are ultimately connected.
Does not correspond to size but degree of sensitivity.

Question 31

Function premotor areas

Answer 31

Set up neural programs for producing organized movements or patterns.

Question 32

What is role prefrontal cortex in control of behavior?

Answer 32

Executive function: processes involved in regulating attention and in determining what to do with info just gathered or retrieved from longterm memory. Planning, behaving, flexibility, especially with new info.

Question 33

How are movement control functions of the nervous system summarized as a hierarchical top down flow of info?

Answer 33

1. Motivation & planning of movement: Limbic system (motivation) + association cortex (planning)
2. Generation of programs of movement: basal ganglia and cerebellum + premotor cortex
3. Refinement of programs for individual movement components: primary motor cortex + motor nuclei upper brain stem
4. Maintenance of posture and smooth execution: motor nuclei of lower brainstem and spinal cord

Question 34

Definition hormones

Answer 34

Chemical messengers that are secreted into the blood. Neurotransmitters are fast, hormones are slow. Act on target tissues.

Question 35

Long tem (sometimes irreversible) vs short term effects hormones

Answer 35

Long: androgens (e.g. testosterone, estrogen) before birth
Short: cortisol

Question 36

How does the brain control release of hormones from the two lobes of the pituitary and thereby control the release of other hormones as well?

What area produces releasing factors that lead to release hormones by anterior part?

Answer 36

It is the master endocrine gland because it produces hormones that in turn stimulate the production of other hormones in other glands including the adrenal cortex and the gonads.
Posterior lobe is part of the brain and consitsts of modified neurons (neurosecretory cells).
Anterior lobe is not part of the brain but connected to it via cappilaries. Hypothalamus prodcues releasing factors (hormones) that are secreted into the capillaries and go to anterior pituitary, where they stimulate anterior pituitary to elease homones into bloodstream.

Question 37

What is some evidence that testosterone is needed to maintain a male’s sex drive?
What is the name of the area in hypothalamus that has receptors for testosterone

Answer 37

Castration > decline sex drive.

Medial preoptic area in hypothalamus has receptors for testosterone.

Question 38

What kind of experiences have been shown to increase testosterone production in men? What effects might such increased testosterone have on a man’s subsequent behavior?

Answer 38

Winning, plasant social encounters with women, driving a luxury automobile.
Men might seek more of this behavior.

Question 39

What evidence indicates that ovarian hormones act directly on the brain to activate sexual drive in female rats?
How do female primates differ from female rats concerning regulation of sexual drive?

Answer 39

Removal ovaries > decline sex drive
Ventromedial area in hypothalamus has receptors for estrogens

Humans removal ovaries > no decline sex drive but removal adrenal glands does (produce estrogens). Sex drive depends on estrogen

Question 40

In what ways are hemispheres symmetrical and asymmetrical?

Answer 40

Same: primary somatosensory and motor areas.
Different: large areas in the left are specialized for language and comparable areas in the right are specialized for nonverbal, visuospatial analysis of information

Question 41

What is cross-cueing in patients with split brains?

Answer 41

Each hemisphere learns to communicate indirectly with other by observing and responding to the behavior that the other poduces.

Question 42

Definition aphasia

Answer 42

Loss of language ability resulting from brain damage

Question 43

Definition broca’s aphasia.

Where is the damage?

Answer 43

Left lobe, anterior to primary motor area
Nonfluent aphasia: telegraphic speech
Funtion Broca:
1. Articulating words and sentences in a fluent manner
2. Transforming grammatically complex sentences that are heard into simpler ones in order to extract meaning

Question 44

Definition Wernicke’s aphasia:

Answer 44

Right lobe, near primary auditory area
Fluent aphasia: difficultuy understanding meaning of words and finding appropriate words
Function Wernicke:
1. Translating sounds of words into meaning
2. Locating words needed to express intended meaning

Question 45

What brain changes have been observed in rats and mice caged in enriched environments?

Answer 45

1. Increased thickness cerebral cortexes
2. Larger cortical neurons
3. More acetylcholine
4. More synapses per neuron
5. Thicker, more fully developed synapses

Question 46

What kind of learning leads to bigger hippocampus?

Answer 46

Spatial learning

Question 47

How has the discovery of longterm potentiation tended to confirm Hebb’s theory about synaptic strengthening?

Answer 47

Theory Hebb: some synapses in brrain have the property of growing stronger when postsynaptic neurons fire immediately after the presynaptic neuron fires.
LTP Strongly supports the theory: is produced by artificially stimualting with a burst of electrical pulses a bundle of neurons entering a particular region of an animal’s brain. This results in strenghtening of the synapses that those neurons form with post-snaptic neurons so that subsequent weak stimulation of the same bundle elicits a stronger response in the postsynaptic neurons that it would have before.
This is LONG TERM: hours -months

How LTP works in some brain areas: presynaps releases more neurotransmitters and postsynaps develops more receptors.

Question 48

What evidence shows that long term potentiation is involved in learning?

Answer 48

Blocking LTP = inhibiting learning

Neurons that fire together, wire together

Question 49

What area of the brain shows the most substantial change in humans relative to other mammals?

Answer 49

Associative areas and general size

Question 50

Encephalization quotient

Answer 50

Ration between brain weight and body weight