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NEUR 2610 > Chapter 5: How Neurons Communicate and Adapt > Flashcards

Chapter 5: How Neurons Communicate and Adapt Flashcards

1
Q

who was the first to isolate a chemical messenger in their successful heartbeat experiment?

A

Otto Loewi

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2
Q

first neurotransmitter discovered in the PNS and CNS; activates skeletal muscles in the SNS; either excites or inhibits internal organs in the ANS

A

acetylcholine (ACh)

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3
Q

ACh can ___ skeletal muscles in the somatic nervous system and may ___ various internal organs in the autonomic system

A

excite; excite or inhibit

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4
Q

Loewi stimulated ___ to the heart, resulting in the heart rate increasing, and identified the chemical that carries the message to speed up heart rate in frogs as ___

A

the accelerator nerve; epinephrine

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5
Q

chemical messenger that acts as a neurotransmitter in the CNS and as a hormone to mobilize the body for fight or flight during times of stress (aka adrenaline)

A

epinephrine

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6
Q

___ and ___ are the same substance, produced by the adrenal glands located ___

A

adrenaline + epinephrine; atop the kidneys

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7
Q

in mammals, the chemical that accelerates heart rate is ___

A

norepinephrine

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8
Q

Loewi’s experiments show that acetylcholine from the vagus nerve ___ heartbeat, and epinephrine from the accelerator nerve ___ it

A

inhibits; excites

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9
Q

neurotransmitter that accelerates heart rate in mammals; found in the brain and in the sympathetic division of the ANS; aka noradrenaline

A

norepinephrine

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10
Q

chemical messengers released by a neuron onto a target to cause an excitatory or inhibitory effect

A

neurotransmitters

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11
Q

outside the CNS, many of the neurotransmitters circulate the bloodstream as ___

A

hormones

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12
Q

under the control of the hypothalamus, the ___ releases hormones into the bloodstream to excite/inhibit targets

A

pituitary gland

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13
Q

why are hormones slower than CNS neurotransmitters?

A

they have to travel larger distances to get to their receptors

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14
Q

the confirmed # of transmitters is ___, with most of the work being done by ___

A

60; 10

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15
Q

disorder of the motor system correlated w/ a loss of dopamine from the substantial nigra and characterized by tremors, muscular rigidity, and a reduction in voluntary movement

A

Parkinson disease

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16
Q

who found that, in Parkinson disease, the substantial nigra had degenerated?

A

Constantin Treatikoff

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17
Q

chemical examination of the brains of Parkinson patients showed that disease symptoms appear when the level of ___ was reduced to ___ of normal in the basal ganglia

A

dopamine; less than 10%

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18
Q

Urban Ungerstedt found that injecting a neurotoxin called ___ selectively destroyed the dopamine-containing neurons and produced symptoms of Parkinson disease

A

6-hydroxydopamine

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19
Q

loss of dopamine-containing substantia nigra neurons has been linked to environmental factors such as ___

A

insecticides, herbicides, fungicides, flu virus, toxic drugs

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20
Q

some Parkinson patients who receive dopaminergic drugs as therapy have become ___, despite showing no such tendencies before treatment

A

shopaholics or compulsive gamblers

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21
Q

membranous compartment that encloses a fixed number (quantum) of neurotransmitter molecules

A

synaptic vesicles

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22
Q
A

a. microtubule
b. mitochondrion
c. synaptic vesicle
d. storage granule
e. postsynaptic receptor
f. presynaptic membrane
g. synaptic cleft
h. postsynaptic membrane
i. neurotransmitter
j. channel

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23
Q

transport structure that carries substances to the axon terminal

A

microtubule

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24
Q

organelle that provides the cell with energy

A

mitochondrion

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25
Q

round granule that contains neurotransmitter

A

synaptic vesicle

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26
Q

large compartment that holds synaptic vesicles

A

storage granule

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27
Q

site to which a neurotransmitter molecule binds

A

postsynaptic receptor

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28
Q

encloses molecules that transmit chemical messages

A

presynaptic membrane

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29
Q

small space separating presynaptic terminal and postsynaptic dendritic spine

A

synaptic cleft

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30
Q

contains receptor molecules that receive chemical messages

A

postsynaptic membrane

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31
Q

how does the astrocyte surrounding the synapse contribute to chemical neurotransmission?

A
  • supplying the building blocks for neurotransmitter synthesis
  • confining the movement of neurotransmitters to the synapse
  • mopping up excess neurotransmitter molecules
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32
Q

functional integration and physical proximity of the presynaptic membrane, postsynaptic membrane, and their intimate association w/ surrounding astrocytes

A

tripartite synapse

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33
Q

5 step process of neurotransmission

A
  1. the neurotransmitter is synthesized inside the neuron
  2. it’s packaged + stored within vesicles at the axon terminal
  3. it’s transported to the presynaptic membrane + released into the cleft in response to an action potential
  4. it binds to + activates receptors on the postsynaptic membrane
  5. it’s degraded or removed so it will not continue to interact w/ a receptor and work indefinitely
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34
Q

process that occurs when a neurotransmitter is released from a presynaptic neuron and binds to a receptor on the postsynaptic neuron

A

anterograde synaptic transmission

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35
Q

protein molecule that pumps substances across a membrane

A

transporter

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36
Q

___ transmitters are synthesized in the cell body, packed in membranes on the Golgi bodies, and transported on microtubules to the axon terminal

A

peptide

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37
Q

___ transmitters cannot be packaged/stored in vesicles, which are composed of lipids, but are rather synthesized “on demand” when an action potential reaches the axon terminal

A

lipid

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38
Q

___ transmitters are generated within the cells by enzymes, but they are able to permeate cell membranes and thus are not stored within the cell

A

gaseous

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39
Q

___ are not biochemically synthesized but are made in the hearts of dying stars, can be packed/stored in vesicles, and released into synaptic cleft

A

ion

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40
Q

neurotransmitters that are packaged into vesicles can be found at 3 locations at the axon terminal

A
  1. granules
  2. microfilaments
  3. presynaptic membrane
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41
Q

the presynaptic membrane is rich in ___ channels

A

voltage-activated Ca+ channels

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42
Q

3 steps of neurotransmitter release

A
  1. when an action potential reaches the voltage-sensitive terminal, it opens calcium channels
  2. incoming calcium ions bind to proteins, forming a complex
  3. this complex binds to vesicles, releasing some from filaments + inducing others to bind to the presynaptic membrane and to empty their contents by exocytosis
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43
Q

protein that has a binding site for a specific neurotransmitter and is embedded in the membrane of a cell

A

transmitter-activated receptors

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44
Q

embedded membrane protein; acts as
1. a binding site for a neurotransmitter
2. a pore that regulates ion flow to directly/rapidly change membrane voltage

A

ionotropic receptors

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45
Q

embedded membrane protein with a binding site for a neurotransmitter linked to a G protein; can affect other receptors or act with second messengers to affect other cellular processes, including opening a pore

A

metabotropic receptor

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46
Q

self-receptor in a neuronal membrane; that is, it responds to the same transmitter released by the neuron; part of a negative feedback loop allowing the neuron to adjust its output

A

autoreceptors

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47
Q

who concluded that the smallest postsynaptic potential is produced by the release of the contents of just 1 synaptic vesicle?

A

Bernard Katz

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48
Q

of neurotransmitter molecules, equivalent to the content of a single synaptic vesicle, that produces a just-observable change in postsynaptic electric potential

A

quantum

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49
Q

the # of quanta released from the presynaptic membrane in response to a single action potential depends on:

A
  1. the amt of Ca+ that enters the axon terminal in response to the action potential
  2. the # of vesicles docked at the membrane, waiting to be released
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50
Q

neurotransmitter inactivation can happen in 4 ways:

A
  1. diffusion
  2. degradation
  3. reuptake
  4. astrocyte uptake
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51
Q

7 types of synapses

A
  1. dendrodendritic
  2. axodendritic
  3. axoectracellular
  4. axosomatic
  5. axosynaptic
  6. axoaxonic
  7. axosecretory
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52
Q

dendrites send messages to other dendrites

A

dendrodendritic

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53
Q

axon terminal of one neuron synapses on dendritic spine of another

A

axodendritic

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54
Q

terminal with no specific target - secretes transmitter into extracellular fluid

A

axoextracellular

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55
Q

axon terminal ends on cell body

A

axosomatic

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56
Q

axon terminal ends on another terminal

A

axosynaptic

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57
Q

axon terminal ends on another axon

A

axoaxonic

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58
Q

axon terminal ends on tiny blood vessel and secretes transmitter directly into blood

A

axosecretory

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59
Q

which type of synapse is the most common in mammalian nervous systems?

A

chemical

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60
Q

area of contact between adjacent cells in which connexin proteins in each cell form connecting hemichannels, which, when open, allow ions to pass between the two cells (aka electrical synapse)

A

gap junction

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61
Q
A

gap junction

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62
Q

electrical synapses are ___ than chemical

A

faster

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63
Q

gap junctions allow ___ to exchange substances

A

glial cells + neurons

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64
Q

large biomolecules such as ___ cannot fit thru gap junctions

A

nucleic acids + proteins

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65
Q

gap junctions at axon terminal synapsing on dendrites and cell bodies allow for ___ transmission

A

dual chemical + electrical

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66
Q

why do mammals rely on chemical synapses more than gap junctions?

A

chemical synapses = plasticity, they can amplify/diminish a signal, and change with experience, mediating learning
gap junctions = speed + efficiency

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67
Q

neurotransmitters themselves do not determine excitation/inhibition, but ___ make the call

A

the ion channel associated w/ the receptor

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68
Q
  • large active zone
  • wide cleft
  • dense material on membranes
  • round vesicles
A

excitatory synapse

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69
Q
  • small active zones
  • narrow cleft
  • sparse material on membranes
  • flat vesicles
A

inhibitory synapse

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70
Q

the differing locations of excitatory and inhibitory synapses:

A

excitatory = dendritic tree
inhibitory = cell body/soma

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71
Q

the exocytosis mechanism for digestion in a single-celled organism is parallel to the ___ for communication in more complex creatures

A

release of a neurotransmitter

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72
Q
A

ionotropic receptor

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73
Q
A

metabotropic receptor

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74
Q

4 criteria for identifying neurotransmitters

A
  1. the transmitter must be synthesized in the neuron or otherwise be present in it
  2. when the neuron is active, the transmitter must be released and produce a response in some target
  3. the same response must be obtained when the transmitter is experimentally placed on the target
  4. a mechanism must exist for removing the transmitter from its site of action after its work is done
75
Q

a suspect chemical that has not yet been shown to meet all the neurotransmitter criteria

A

putative transmitter

76
Q

why is identifying chemical transmitters in the CNS hard?

A

there are thousands of synapses packed around every neuron, preventing easy access to a single synapse + its activities

77
Q

all motor neuron axons leaving the spinal cord use ___ as a transmitter

A

acetylcholine

78
Q

explain the Renshaw loop

A
  • each axon has an axon collateral within the spinal cord synapses on a nearby CNS interneuron
  • this interneuron synapses on the motor neuron’s cell body
79
Q

what enables a motor neuron to inhibit itself from overexcitation?

A

the Renshaw loop

80
Q

today, the term neurotransmitter applies to chemicals that:

A
  1. carry a message from the presynaptic membrane of one neuron to another by influencing postsynaptic membrane voltage
  2. change the structure of a synapse
  3. communicate by sending messages in the opposite direction
81
Q

5 classes of neurotransmitters:

A
  1. small-molecule
  2. peptide
  3. lipid
  4. gaseous
  5. ion
82
Q

quick-acting neurotransmitter synthesized in the axon terminal from products derived from the diet

A

small-molecule transmitters

83
Q

how do small-molecule transmitters work?

A
  • synthesized from dietary nutrients + packaged ready for use in axon terminals
  • after released from a terminal button, it is quickly replaced at the presynaptic membrane
84
Q

many neuroactive drugs are designed to reach the brain by the same route that ___ transmitters follow - the digestive tract

A

small-molecule

85
Q

ACh molecules are synthesized from ___ by 2 enzymes, then broken down

A

choline + acetate

86
Q

acetylcholine synthesis

A
  1. acetyl CoA carries acetate to the transmitter synthesis site
  2. ChAT transfers acetate to choline to form ACh
87
Q

any chemical in limited supply that restricts the pace at which another chemical can be synthesized

A

rate-limiting factor

88
Q

amine synthesis

A

tyrosine -> L-Dopa -> dopamine -> norepinephrine -> epinephrine

89
Q

what enzyme is the rate-limiting factor in the production of dopamine, norepinephrine, and epinephrine?

A

the 2nd enzyme tyrosine hydroxylase

90
Q

which neurologist administered L-dopa to a patient with Parkinson disease?

A

Oliver Sacks

91
Q

by increasing the amount of dopamine in remaining synapses, L-dopa relieved the symptoms of ____

A

Parkinson disease

92
Q

serotonin is synthesized from the amino acid ___

A

L-tryptophan

93
Q

amine neurotransmitter; helps to regulate mood + aggression, appetite + arousal, perception of pain, and respiration

A

serotonin

94
Q

amino acid neurotransmitter; typically excites neurons

A

glutamate (Glu)

95
Q

amino acid neurotransmitter; typically inhibits neurons

A

gamma-aminobutyric acid (GABA)

96
Q

structural difference between glutamate and GABA

A

they are the same except GABA does not have a carboxyl group on the bottom

97
Q

glutamate is widely distributed in CNS neurons, but it becomes a neurotransmitter only if it is ___

A

appropriately packaged in vesicles at the axon terminal

98
Q

___ is a much more common inhibitory transmitter in the brainstem and spinal cord, where it acts within the Renshaw loop

A

glycine (amino acid transmitter)

99
Q

neurotransmitter that controls arousal + waking; can cause the constriction of smooth muscles; when activated in allergic reactions, constricts airway + contributes to asthma

A

histamine

100
Q

histidine is converted by the enzyme ___ into histamine

A

histidine decarboxylase

101
Q

the purine ___ consists of a molecule of adenine attached to a ribose sugar molecule and 3 phosphate groups

A

adenosine triphosphate (ATP)

102
Q

a molecule that plays a central role in promoting sleep, suppressing arousal, + regulating blood flow to various organs thru vasodilation

A

adenosine

103
Q

short, multifunctional amino acid chain (fewer than 100); acts as a neurotransmitter + can act as a hormone; may contribute to learning

A

neuropeptides/peptide transmitters

104
Q

the process of neuropeptide synthesis/transport is relatively ___ compared to small-molecule neurotransmitters

A

slow

105
Q

neuropeptides perform an enormous range of functions in the nervous system, acting as hormones that:

A
  • respond to stress
  • enable a mother to bond with her infant
  • regulate eating + drinking, pleasure + pain
  • contribute to learning
106
Q

opium, morphine + related synthetic chemicals like heroin mimic the actions of endogenous brain opioid neuropeptides:

A

enkephalins, dynorphins, endorphins

107
Q

___, released in response to exercise (runner’s high), has many times the analgesic potency of morphine

A

beta-endorphin

108
Q

unlike many transmitters that bind to receptors associated w/ ion channel, neuropeptides are ___ and have no direct effects on ___

A

metabotropic; postsynaptic membrane voltage

109
Q

peptide transmitters activate ___ that indirectly influence ___

A

synaptic receptors; cell structure + function

110
Q

why can’t neuropeptides be taken orally as drugs like small-molecule transmitters?

A

digestive processes degrade neuropeptide amino acid chains

111
Q

class of lipid neurotransmitters, including anandamide + 2-AG, synthesized at the postsynaptic membrane to act on receptors at the presynaptic membrane; affects appetite, pain, sleep, mood, memory, anxiety, and stress response

A

endocannabinoids

112
Q

___ is the target of all cannabinoids, and are found at ___

A

CB1 receptors; both the glutamate and GABA synapses

113
Q

___ act as neuromodulator to inhibit release of glutamate and GABA, thus dampening ___

A

cannabinoids; neuronal excitation/inhibition

114
Q

3 gaseous neurotransmitters

A
  1. nitric oxide (NO)
  2. carbon monoxide (CO)
  3. hydrogen sulfide (H2S)
115
Q

how do gaseous transmitters work?

A
  • cells synthesize them on demand
  • gas diffuses away, easily crossing cell membrane, immediately becoming active
116
Q

gaseous neurotransmitter; acts to dilate blood vessels, aid digestion, & activate cellular metabolism

A

nitric oxide (NO)

117
Q

gaseous neurotransmitter; activates cellular metabolism

A

carbon monoxide (CO)

118
Q

gaseous neurotransmitter; slows cellular metabolism by preventing oxygen from binding in the mitochondria

A

hydrogen sulfide (H2S)

119
Q

2 parts of an ionotropic receptor

A
  1. a binding site for a neurotransmitter
  2. a pore/channel
120
Q

how does an ionotropic receptor work?

A
  • neurotransmitter attaches to binding site
  • receptor quickly changes shape, either opening the pore or closing it
121
Q

ionotropic receptors are usually ___ because ___

A

excitatory; they bring about rapid changes in membrane voltage

122
Q
A

ionotropic receptor

123
Q

how does a metabotropic receptor work?

A
  • transmitter binds to receptor
  • triggers activation of a G protein
  • affects ion channels or cells metabolic activity
124
Q
A

metabotropic receptor

125
Q

guanyl nucleotide-binding protein couples to a metabotropic receptor; binds to other proteins when activated

A

G protein

126
Q

3 subunits of G protein

A

alpha, beta, gamma

127
Q

what does the alpha subunit do on a G protein?

A
  • detaches when a neurotransmitter binds to G protein’s receptor
  • detached subunit can bind to other proteins within cell membrane or intracellular fluid
128
Q

what happens when an alpha subunit binds to a nearby ion channel?

A

the channel structure changes, modifying the flow of ions (open/close) - this influences membrane’s electric potential

129
Q

what happens when an alpha subunit binds to an enzyme?

A

second messenger is activated

130
Q

metabotropic receptors allow for the possibility that a single neurotransmitter’s binding to a receptor can activate an escalating sequence of events called ___

A

an amplification cascade

131
Q

the amplification cascade effect results in ___

A

many downstream proteins (second messengers, channels or both) being either activated or deactivated

132
Q

ACh has an excitatory effect on skeletal muscles, where it activates an ___ receptor, and an inhibitory effect on heart rate, where it activates a ___ receptor

A

ionotropic; metabotropic

133
Q

how is there variety of small-molecule neurotransmitter receptor subtypes?

A

alternative forms of each subunit can assemble in unique combinations to make a functional receptor

134
Q

why does the brain contain so many receptor types for each neurotransmitter?

A

each subtype has slightly different properties which confer different activities

135
Q

can different transmitters coexist in the same terminal or synapse?

A

yes

136
Q

neurons that use acetylcholine as its main neurotransmitter

A

cholinergic neurons

137
Q

at a skeletal muscle, cholinergic neurons are ___

A

excitatory, producing muscle contractions

138
Q

the main transmitter-activated ionotropic channel receptor

A

nicotinic acetylcholine receptor (nAChr)

139
Q

what happens when ACh or nicotine binds to the nAChr?

A

the pore opens, allowing simultaneous efflux of K+ and influx of Na+, depolarizing the muscle fibre

140
Q

cholinergic neurons in the CNS synapse with ___ to prepare the body’s organs for fight or flight

A

sympathetic norepinephrine (NE) neurons

141
Q

cholinergic neurons in the CNS synapse with ___ to prepare the body’s organs for rest and digest

A

parasympathetic acetylcholine (ACh) neurons

142
Q

norepinephrine (NE) receptors on the ___ are excitatory, while NE receptors on the ___ are inhibitory

A

heart; gut

143
Q

acetylcholine (ACh) receptors on the ___ are excitatory, while ACh receptors on the ___ are inhibitory

A

gut; heart

144
Q

the ENS uses over __ neurotransmitters that are identical to those in the CNS

A

30

145
Q

the 2 main small-molecule transmitters used by the ENS are:

A

serotonin + dopamine

146
Q

neural pathways that coordinate brain activity thru a single neurotransmitter; its cell bodies lie in a brainstem nucleus; axons are distributed thru a wide CNS region

A

activating systems

147
Q

the 4 activating systems

A
  1. cholinergic
  2. dopaminergic
  3. noradrenergic
  4. serotonergic
148
Q
  • active in maintaining attention + waking EEG pattern
  • plays a role in memory by maintaining neuron excitability
  • death of these neurons and decrease in this neurotransmitter in the neocortex are related to Alzheimer disease
A

cholinergic system (acetylcholine)

149
Q
  • this transmitter release causes repetition of behaviours
  • the neurotransmitter system most affected by addictive drugs + behaviours
  • increases in this transmitter activity may be related to schizophrenia
  • decreases in this transmitter activity may be related to deficits of attention
A

mesolimbic pathways of the dopaminergic system

150
Q
  • active in maintaining normal motor behaviour
  • loss of this neurotransmitter is related to muscle rigidity + dyskinesia in Parkinson disease
A

nigrostriatal pathways of the dopaminergic system

151
Q
  • active in maintaining emotional tone
  • decreases in its neurotransmitter activity are related to depression
  • increases in its neurotransmitter are related to mania
  • decreased neurotransmitter activity is associated with hyperactivity and ADHD
A

noradrenergic system (norepinephrine)

152
Q
  • active in maintaining waking EEG pattern
  • changes in its neurotransmitter activity are related to OCD, tics and schizophrenia
  • decreases in its neurotransmitter activity are related to depression
  • abnormalities in brainstem 5-HT neurons are linked to disorders like sleep apnea and SIDS (sudden infant death syndrome)
A

serotonergic system (serotonin)

153
Q

in a rat brain, AChE permeates the cortex and is especially dense in the ___

A

basal ganglia

154
Q

2 treatment strategies for Alzheimer disease

A

drugs that either
- inhibit enzyme acetylcholinesterase (raises levels of ACh)
- raise the # of nicotinic receptors

155
Q

how can Parkinson disease be triggered by the ingestion of certain toxic drugs?

A

the drugs may act as selective neurotoxins that specifically kill dopamine neurons in the substantia nigra

156
Q

how many people does Parkinson disease affect?

A

20 per 100,000

157
Q

behavioural disorder characterized by delusions, hallucinations, disorganized speech, blunted emotion, agitation or immobility, + a host of associated symptoms

A

schizophrenia

158
Q

how many people does schizophrenia affect?

A

1 in 100

159
Q

mood disorder characterized by prolonged feelings of worthlessness and guilt, disruption of normal eating habits, insomnia, a general slowing of behaviour, frequent thoughts of suicide

A

major depression

160
Q

disordered mental state of extreme excitement

A

mania

161
Q

behaviour characterized by compulsively repeated acts and repetitive, often unpleasant, thoughts

A

obsessive-compulsive disorder (OCD)

162
Q

___ brains with more ___ are more plastic, thus likely to show more alterations in neural organization

A

large; synapses

163
Q

relatively persistent/permanent change in behaviour that results from experience

A

learning

164
Q

when an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A’s efficiency, as one of the cells firing B, is increased

A

Hebb synapse

165
Q

who described the synaptic basis of learning as: learning in which the conjoint activity of nerve cells serves to link them?

A

Eric Kandel

166
Q

what happens when the marine slug, Aplysia californica, is threatened?

A

it withdraws its vulnerable body parts: the gill & siphon

167
Q

habituation + sensitization are both ___ behaviours for humans

A

unconscious

168
Q

learned behaviour in which the response to a stimulus weakens with repeated presentations

A

habituation

169
Q

small, fast, random eye movements designed to keep photoreceptors exposed to ever-changing visual stimuli to prevent habitation

A

saccades

170
Q

the marine slug, Aplysia californica, ___ to waves in the tidal zone where it lives

A

habituates

171
Q

results of habituation

A
  1. influx of calcium ions in response to an action potential decreases
  2. less neurotransmitter released at presynaptic membrane
  3. less depolarization of postsynaptic membrane
172
Q

conclusion of Eric Kandel’s experiment on the marine slug Aplysia californica

A

withdrawal response weakens with repeated presentation of water jet (habituation) due to decreased Ca2+ influx & subsequently less neurotransmitter release from the presynaptic axon terminal

173
Q

can sensory/motor neurons generate action potentials after habituation?

A

yes

174
Q

as habituation develops , the EPSP’s in the motor neuron become ___

A

smaller

175
Q

how do the EPSPs in the motor neuron decrease in size as habituation develops?

A

the motor neuron is receiving less neurotransmitter from the sensory neuron across the synapse, indicating habituation is also taking place in the presynaptic axon terminal of sensory neurons

176
Q

as habituation happens, the Ca2+ influx ___ in response to the voltage changes associated w/ an action potential

A

decreases

177
Q

voltage-activated calcium channels during habituation become ___ responsive to voltage changes + more ___ to the passage of calcium ions

A

less; resistant

178
Q

learned behaviour in which the response to a stimulus strengthens with repeated presentations

A

sensitization

179
Q

neural results from sensitization

A
  1. serotonin reduces K+ efflux thru potassium channels, prolonging an action potential on the siphon sensory neuron
  2. the prolonged action potential results in more Ca2+ influx & increased transmitter release
  3. causes greater depolarization of the postsynaptic membrane after sensitization
180
Q

sensitization vs. habituation

A

sensitization: influx of Ca2+, more neurotransmitter release, potassium channels
habituation: efflux of Ca2+, less neurotransmitter release, calcium channels

181
Q

the # and size of synapses ___ in habituation, and ___ in sensitization

A

decreases; increases

182
Q

what plays an important role in carrying instructions about structural changes during learning to nuclear DNA?

A

the second messenger cAMP

183
Q

in the fruit fly Drosophila, the genetic mutation ___ lacks the enzymes necessary to degrade cAMP, resulting in abnormally high levels, while the other mutation ___ reduces levels of cAMP below the normal range

A

dunce; rutabaga

184
Q

fruit flies with both mutations dunce or rutabaga are impaired in acquiring habituation/sensitized responses (learning) bc their levels of ___ cannot be regulated

A

cAMP

NEUR 2610 (8 decks)

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