Neurobiology Midterm Flashcards
1
Q
2 classes of neural cells
A
Excitable and non excitable
2
Q
Glial cells are continually ___ by precursors throughout adulthood
A
Replaced
3
Q
Roles of glial cells (5)
A
- modulate synaptic functions
- maintain chemical homeostasis
- regulate blood flow in capillary beds
- immune functions
- scaffolding for neuronal migration
4
Q
Myelinations role in conduction
A
increases conduction velocity
5
Q
Non neuronal cells of vertebrate brains
A
Astrocytes, oligodendrocytes, endothelial cells, microglial cells
6
Q
Endothelial cells that line ventricles
A
Ependymal cells
7
Q
Ependymal cells derived from ____ and produce ____
A
radial glia, cerebrospinal fluid
8
Q
____ are a type of ependymal cell that line the _____
A
tanycytes, 3rd ventricle
9
Q
radial glia can serve as ____ to generate neural progenitors during development
A
stem cells
10
Q
In adults radial glia generate neurons in _____
A
sub-ventricular zones
11
Q
Types of myelinating cells
A
Oligodendrocytes (CNS) , schwann cells (PNS)
12
Q
Microglia are derived from ______ stem cells
A
hemopoetic
13
Q
Actrocytes are an essential component of the _____ and help maintain _______
A
blood brain barrier, brain water homeostasis
14
Q
Astrocytes have a role in sequestration/redistribution of ___
A
K+
15
Q
Blood flow in the brain is locally regulated by
A
Neuronal Activity (more activity more blood flow)
16
Q
Smooth muscles on _______ contract/relax based on signalling from ______
A
arterioles, astrocytes
17
Q
Intrinsic imaging uses red and green reflectance. Green reflectance doesn’t change with ______ but does change with ______
A
Changes in oxygenation, chnages in total blood flow (more blood, more absorbance, less reflectance)
18
Q
MRI based on _____, fMRI based on _____
A
water distribution, paramagnetic properties
19
Q
Red reflectance in intrinsic imaging influenced by ratio of ______
A
oxy : deoxy Hb
20
Q
Decreased reflectance can come from
A
shift from oxy to deoxy Hb
oxyHb = oxyhemoglobin (oxygen bound state of hemoglobin)
21
Q
More reflectance as more
A
oxy Hb is introduced (not a good absorber)
22
Q
Neurons are distinguishable by proteins they express. (heterogeneity at a cellular level) proteins mentioned in class:
A
- NPY (neuropeptide Y)
- Parvalbumin = Ca
binding
protein/buffer - nNOS (neuronal
nitric oxide
synthase ~enzyme) - Galanin (a
neuropeptide)
23
Q
Purkinje cells are _____ neurons found in the ______
A
inhibitory, cerebellum
24
Q
Thalamic relay neuron firing: _____ when awake, _____ when asleep
A
tonic, burst
25
Externally recognizable parts of a neuron:
| think basic anatomy of a neuron
- soma (cell body)
- dendrites (spiny or smooth)
- axon and axon collaterals (branches
- terminals (presynaptic release sites)
26
Why does soma have 1. lots of ER and 2. lots of mitochondria at synapse?
1. protein synthesis
2. signalling is electrically expensive
27
Number of inputs received by a neuron depend on
size/complexity of dendritic arbor
28
Dendrites contain actin filaments for
transport/motility functions (extend and retract spines)
29
Neurons are elctro-chemical units, meaning ions do not _____ along axon
Diffuse
30
Why are synaptic clefts so small?
NTs can only diffuse very short distances (~15nm)
31
In order for synapse to occur there must be
| transmitters can be released, but synapse will not occur without
transmitter receptors on postsynaptic side
32
Directed synapses
| characteristics
- ionotropic
- NT released directly into cleft onto receptors
33
Non-directed synapses
| characteristics
- hormonal, neuromodulatory
- transmitter released onto receptors further away
- metabotropic
34
______ built the first _______ microscope
Winfried Denk, 2-photon (taking small sections and putting them together with a computer)
35
Fluorescence
photons that sluff off of photonic light after it reaches an excited state
36
Parvalbumin acts as a __ buffer
Ca2+/calcium
37
Dendritic spines can _______ biochemical processes driven by _____
compartmentalize, calcium
38
NMDAR driven ____ signals increase in _____ when they reach the thin dendritic tip end
Calcium, amplitude
39
Convergence
Number of neuronal inputs converging on one neuron (receive)
40
Divergence
Number of neurons onto which one neuron synapses (give)
41
Serial Electron Mircoscopy
- diamond knife
- many slices with imaging of surface after each slice
- winfried denk
42
Dendritic spine neck contains ____, narrow neck = _____
ER, high resistance
43
When a neuron synapses all along an axon it's known as a(n)
En passant synapse
44
_____ are phagocytotic cells in brain, ______ cells act as scaffold for neurons to migrate along
microglia, radial glia
45
Concentration of nervous tissue at front of animal is called _____
cephalization
46
Archicortical brain tissue organization is retained in mammals in the _____. Evolving from rodent to primate ______ neocortex expanded more than primary sensory cortex
Hypothalamus, association
47
Voltage gated __ channels are formed from 4 subunits while single polypeptide folds on utself to form __ and ___ types of ion channels
K+, Na+, Ca2+
48
MS patients can have periods of remission because
myelination is ongoing and can build back up
49
Myelinating an axon increases conduction velocity by increasing __ and decreasing __
Rm, Tau
50
Why does burst stop in bursting neurons?
build up of Ca2+ inside the cell activates the collocalized KCa2+ channels to repolarize cell
51
How to determine time constant
find place on curve where the capacitor is charged to ~67% of it's maximum value
52
In mouse retina ______ cells respond preferentially to objects passing __________
direction selective ganglion, across retina in one direction
53
Neuron doctrine
Nerve cells are discrete entities, they communicate by specialized contact sites and there is not continuity between the cells
*Ramon y Cajal, Golgi, Sherrington
54
Active zone
place where synaptic vesicles discharge NT into synaptic cleft,
lots of docked vesicles collocalized with Ca channels
55
Vesicle vs Secretory granules
Both are membrane bound areas, vesicles hold and release NT, granules are electron dense
Vesicles- small molecule
Granules - neuropeptides
56
Postsynaptic density (PSD)
A cytoskeletal junction in developing synapses that may serve to organize postsynaptic receptors and speed their response to neurotransmitter
57
Spinous vs Aspinous
Spinous = neurons that exhibit dendritic spines
Aspinous = smooth dendritic neurons
* pyramidal cells are always spiny
58
4 types of dendritic spines
mushroom, thin, stubby, and filopodia
59
Stellate cells
inhibitory neurons in cerebellum that project onto purkinje cells
60
Telencephalon
The part of the brain derived from the anterior part of the embryonic forebrain vesicle (cerebral hemispheres)
*most highly developed part of the forebrain
61
Diencephalon
Portion of the brain derived from the posterior part of the embryonic forebrain vesicle that lies just rostral to the midbrain (thalamus/hypothalamus)
62
Cephalization happened at the same time as ____
bilateral symmetry
63
Cnidarians have _____, which is a collection of ____ instead of a brain
the nerve net, ganglion
64
With segmentation came _______
segmental ganglia
* can be nociceptive or sex specific
65
Arthropods have ____ and _____of segments
fusion, specialization
*ie. circumesophageal ganglia (around esophagus)
66
Gastropods have _____ that can fire APs
large somata
67
In invertebrates, smaller neurons process ______ signals
olfactory/olfacto-spatial info
68
Squid vs Human eye
Squid: photoreceptors have axons, no complex local processing
Humans: no axons/APs from photoreceptors, complex processing at retina
69
What are central pattern generators?
neuronal circuits that when activated can produce rhythmic motor patterns such as walking, breathing, flying, and swimming in the absence of sensory or descending inputs
70
2 ways to set up central pattern generators
1. half-centre oscillator (two cells connected by reciprocal inhibition)
2. neurogenic (rhythm generator)
71
In central pattern generators all synapses are _____
inhibitory
72
Central pattern generator removal of inhibition leads to _____
firing (disinhibition)
73
Polymorphic Networks
anatomical circuits that can
dynamically re-wire to
have different functions – due to
modulators OR different
sensory input.
74
Mammalian locomotion is organized by _________ in the _________
central pattern generators, spinal cord
75
Limitations in invertebrate body plan arise from
- limitations of respiratory/circulatory systems
(ability to diffuse through thick tissues)
76
In evolutionary progression (birds and mammals) of chordate brains, _______ enlarged, and became a centre for _________, __________, ________
cerebellum, balance, equilibrium, coordination
77
________ became specialized as the optic lobes
midbrain
78
Anterior of the forebrain makes up the _______ while the posterior houses the _______ and _______
cerebrum, thalamus, hypothalamus
| telencephalon= cerebrum
diencephalon = thalamus/hypothal
79
This area of the brain expanded disproportionately in chordate evolution
Forebrain
80
Electric fish have large _______ because it is essential in generating & interpreting _______
cerebellums, electrical fields
81
Hippocampus has a __ layered _________
3, archicortex
82
Mammalian evolution characterized by expansion of __ layered ______
6, neocortex
83
Thalamic (sensory) neurons project a lot into layers __ & __ of the neocortex
3 & 4
84
Interneurons mainly make _____ connections, most being _______
local, inhibitory
85
________ is an excitatory type of interneuron, _______, ________ are inhibitory subtypes
spiny stellate, basket, chandelier
85
in chordate evolution a increased proportion of __________ and a decreased proportion of _________ is seen
forebrain, midbrain
85
Most dense part of the brain
Granule layer of cerebellum
85
6 layer cortex is evolutionary addition to preexisting _______
allocortex
85
Purpose of Gyrification
to increase surface area of brain within the skull
86
Subthreshold current injected into one part of the axon spreads _______ until the current is dissipated by ________
passively, leakage
87
Length constant is
measure of steady-state voltage decay with distance in a neuron, decay to ~37% of max voltage (leakier axon = shorter length constant)
88
Length constant is improved by increasing ___, and decreasing __ & __
Rm, Ri, Ro
89
Time constant is defined as
the time when the voltage response (Vt) rises to 63% of the voltage max (Vinf)
90
The time constant characterizes how rapidly _________ changes the ________
current flow, membrane potential
90
Time constant depends on physical properties ____ & ____
membrane resistance (Rm) and capacitance (Cm)
91
Larger cells have lower _______ and larger _______
resistances, capacities
92
Small cell = ______ time constants (and vice versa)
large
| smaller neurons have higher membrane resistance (less leak)
tau = Rm*Cm
93
A receptor potential large enough to drive an ______ is considered a __________
action potential, generator potential
94
passive = voltage change ________ current
active = voltage change __________ current
directly proportional to, determined by but not proportional to
95
Receptor potential: (active or passive)
Synaptic potential:
Action potential:
passive, passive, active
96
Membrane potential is produced by movement of K+ from ______ to _______ of neuron via _______ channels. This generates a _______ charge inside relative to outside.
inside, outside, leak, negative
97
How are changes in membrane potential produced?
Changing of selective permeability
98
While squid and mammals have very different ion concentrations inside and outside the cells, what is similar about the ion balance?
the ratios of inside to outside are very similar
99
Ion channels allow ions to diffuse _________ ________ gradient
down the electrochemical
* and are selectively permeable
100
Permeability is required to
| why are permeability changes useful
"harvest" voltage from a concentration gradient
101
To balance ionic pressure ________ do not diffuse membrane
non-ionic compounds
102
Resting ______ potential of giant squid axon is primarily determined by ___________
membrane, K+ concentration gradient
103
________ is more effective than ________ at changing voltage because K+ has greater resting permeability than Na+
potassium, sodium
104
membrane potential can change from resting when: (3 points)
1. membrane permeability changes (quick)
2. activity of an electrogenic pump changes
3. concentration of an ion the mem is permeable to changes (much slower change)
105
An electrogenic pump is
an ion pump that generates a net flow of charge
| example: Na/K pump brings in 2 K for every 3 Na out, creates (-) charge
106
The key to electrical signalling by rapid voltage changes:
controlled opening/closing of ION CHANNELS
107
If conductance/permeability increases for a certain ion, the membrane potential will
get closer to the ions nernst equilibrium (and vice versa)
* less influenced by decrease in an ions conductance
108
Direction of net flux
Will be such that membrane potential is nearer to Nernst potential of ion
| negative ions with positive driving force = influx,
negative df = efflux
109
Tau away from the beginning of graph = ___%
Tau away from peak of graph where voltage starts dissipating = ___ %
63, 37
110
Because as currents flow through channels the voltage is impacted by the changes in permeability and in turn the voltage changes the channel opening... this is studied using ______
a voltage clamp
111
In order to flow, all currents depend on a ___________
driving force acting on the ions
* this driving force changes with Vm
112
If no voltage gated channels are open, current (I) is determined by _(equation)_, but __ is not constant due to __________ always being open
I=V/R, R, leak channels
113
tetrodotoxin from a puffer fish gets rid of all ___ channels so current can only be carried by ___ channels
Na+, K+
114
___ channels are quick to open, ___ channels open later
Na+, K+
115
Vm > Eion = net flux ___
out
116
More depolarized = _____ likely for channel to open
more
117
Na+ current is ______ K+ current is ______
inward, outward
118
Na+ conductance rises and falls more _______ than K+ conductance due to the speed at which their respective channels open/close
quickly/rapidly
119
________ increases K+ and Na+ conductances
depolarization
120
An action potential requires a __________ inward Na+ conductance that ________, and a _________ K+ that _________
fast-acting, turns off, slower, persists
121
_______ refractory is followed by _______ refractory
absolute, relative
122
Why do we need K+ channels to repolarize if Na+ channels shut off on their own?
K+ channels speed up membrane potential repolarization and allow for repetitive neuronal firing at high frequencies
123
Action potential conduction requires both:
active and passive current flow
124
Propagation of AP is followed by wave of ___________. This is caused by the inactivation of __ channels and the opening of __ channels, and prevents ________________.
refractoriness, Na+, K+, backward propagation
125
Voltage gated Na+ channel are localized to the _____________
| *signal transduction
nodes of ranvier
126
Loss of myelin (like in MS) can lead to __________ of Na+ channels. Less density = less _________
redistribution, excitability
127
__________ is an experimental MS treatment, which induced differentiation of __________________ and enhanced ____________
benztropine, oligodendrocyte precursor cells, remyelination
128
K channels are composed of ________
4 different subunits
129
To pass through a potassium channel, an ion must remove most of its surrounding _________ leaving only ___. The selectivity filter for a sodium channel is slightly _______ and may accommodate an Na+ ion with __ attached water molecules
water molecules, 2, larger, 3
130
______ blocks SK channels but not IK channels
* types of calcium activated K channels
apamin (from bee venom)
131
Cl-channels have __ pores
2
| this might be a lie, don't know what slide i pulled it from
132
Voltage gated calcium channels have many types:
P-type, T-type, N-type, R-type, L-type
P: blocked by agatoxin from funnel web spiders
T: blocked by Ni2+ ions
N: blocked by conotoxin GVII from cone snails
R: “resistant” to blockers of P and N
L: blocked by dihydropyridines
*doubt we'll need to know these specs
133
Of the types of voltage gated calcium channels, 4 are high voltage activated and 1 is low voltage activated. The low voltage type is
T-type (transient)
| - can be activated by baby depols
- triggers burst
134
Simple bursting neurons need 3 currents:
| (from3 different ions)
1. persistent Na ~drives neuron to threshold
2. Voltage gated Ca ~ open with each AP
3. Ca dependent K ~ grows as Ca builds
135
Na channel toxins (from slide)
- tetrodotoxin (puffer fish)
- saxitoxin (marine dinoflagellates)
- alpha-toxin (scorp, delays inactivation)
136
K channel toxins (from slide)
- dendrotoxin (snake)
- batrachotoxin (frog)
- charybdotoxin (scorp)
137
__________ are diseases caused by mutations in voltage gated channels
channelopathies
138
Slowing of Na channel _________ leads to neuronal hyperexcitability, implicated in _________________
inactivation, generalized epilepsy
139
Why is there such diversity of K channels?
Diverse subunits and subtypes of subunits, 4 alpha-subunits combine to make a channel, nearly 100 KCN genes are known with differing properties (activation, gating, and inactivation)
140
Why can't Na pass through K channels and vice versa?
SELECTIVITY FILTERS. In order to shed the correct amount of water molecules to fit, the charges have to interact very closely with the filter. K is too big with 3 waters, but too small to have close interactions with Na channel to shed third water, same goes for Na in a K channel.
141
Examples of Amino acid small molecule transmitters
- glutamate
- aspartate
- GABA
- glycine
142
Examples of biogenic amines
| *think basic neurotransmitters
- dopamine *catecholamines
- norepinephrine *
- epinephrine *
- serotonin (indoleamine)
- histamine (imidazoline)
143
Small molecule NTs
| examples
- ACh
- Purines
- Amino acids
- Biogenic amines
144
Small molecules that are not contained in vesicles (4)
- endocannabinoids (lipid soluble)
- Nitric oxide (gas)
- carbon monoxide (gas)
- adenosine (made from ATP in extracellular space)
145
Aceytlcholine is broken down by _________ into ________ & ________
acetylcholinesterase, acetate, choline
146
________________ catalyzes the synthesis of acetylcholine from ________&_________
choline acetyltransferase, acetyl CoA, choline
147
nACh receptors consist of __________, and have been isolated using ________
5 subunits, alpha-bungarotoxin (from snake venom)
148
At the neuromuscular junction nACh receptors contain 2 ________, both of which need to be bound to ____ for the receptor to be activated. the subunit ratio is: ______
alpha-subunits, ACh, 2alpha:1beta:1sigma:1gamma/epsilon
149
Small molecules have Ionotropic or metabotropic receptors?
trick question it's both
150
Peptides have only ___________ receptors
metabotropic
151
Main difference between ionotropic and metabotropic receptors:
Metabotropic are made up of one protein, whereas ionotropic are made up of multiple protein subunits
152
____________ converts glutamine to glutamate in the ________________. _______________ converts glutamate to glutamine in the ______________.
Glutaminase, presynaptic terminal. glutamine synthetase, glial cells.
153
3 types of ionotropic Glu receptors
AMDA-type, NMDA-type, kainate-type
154
NMDA-type Glu receptor has Ca permeability. Only 1 subtype of AMDA-type has Ca permeability. What is the difference between these two receptor types?
Ca-AMPA has no voltage dependance
155
AMPA receptors are made up of protein subunits. If AMPA receptor lacks _______ subunit, it is Ca permeable
gluR2
156
NMDA-type glutamate receptors are _______ dependant, and have ____ "blockers". Depolarization pushes this block out of the pore.
voltage, Mg2+
157
___ is a marker of GABA-synthesizing terminals. _________ uptake excess GABA
GAD/GAD67, glial cells
158
One enzyme (serine hydroxymethyltransferase) converts glucose to ________
glycine
159
GABA receptors have depolarizing responses in _________ neurons, and hyperpolarizing in _________ neurons
Immature, mature
160
Biosynthetic pathway for catecholamines begins with _________ which is converted into _______ by a RATE LIMITING enzyme ____________
tyrosine, DOPA, tyrosine hydroxylase
161
L-DOPA is a drug used to increase the amount of ________ synthesized by neurons in ____________ patients
dopamine, parkinson's
162
DOPA is converted to dopamine via _______________ (enzyme)
DOPA decarboxylase
163
Dopamine is released from the _________ &________
substantia nigra, ventral tegmental area
164
Norepinephrine is released by the _______________
locus coeruleus
165
Epinephrine is released from the __________________
medullary epinephrine neurons
166
Serotonin is released by ___________
Raphe nuclei
167
Histamine is released by ___________________
tuberomammillary nucleus of hypothalamus
168
Precursor of serotonin is ______________
tryptophan
169
Advantages of storing transmitters in vesicles: (3)
- SPEED ~ more rapid transmitter release all at once
- OSMOLARITY ~ high stored conc. in terminal without throwing off osmolarity of cytoplasm
- STABILITY ~ transmitter protected from degradation
170
Endocannabinoids act by modulating neurotransmission. Effect of CB1 receptor is reducing release of ______ and therefore reducing _________
GABA, inhibition (endocannabinoids inhibit inhibition)
* retrograde control of release
171
Roles of CB1 (receptor involved in endocannabinoid signaling)
| *cannabinoid receptors are GPCRs
- decreases cAMP
- inhibits N and P/Q Ca channels
- facilitates GIRK channels, stabilizes resting Vm
| GIRK= G protein-gated inwardly rectifying potassium channel
172
Nitric oxide (NO) is very important for regulating vascular tone, it promotes __________
relaxation
173
Glutamate and catecholamines are ____________
GABA and glycine are ___________
excitatory, inhibitory
174
Increased intracellular ___ is required for exocytosis of vesicles
Ca2+
175
Endocannabinoids are a family of ___________ signals that interact with __________ receptors such as _____ & _____
endogenous, cannabinoid, CB1, CB2
176
Electrical synapses have no transmission delay, making them useful in _________ circuits. Electrical synapses are very common in __________.
escape, invertebrates
177
Fast chemical synapses
| (multi point answer)
- have very short delay between presyn depol and postsyn response (<1msec)
- Always small molecule (GABA, ACh, Glu etc)
- Postsyn receptor is Ionotropic (metab is slower/lasts longer)
178
Temporal fidelity for fast transmission requires __________ between presynaptic depolarization and transmitter release. To achieve this, presyn ___ channels must be close to ___________ being released
tight temporal coupling, Ca, vesicles
179
Depolarization of presynaptic terminal causes opening of ___ channels, which causes ______ of vesicles with the presynaptic membrane. After transmitter release, vesicular membrane must be _____________
Ca, fusion, retrieved/recycled
180
When a Ca channel blocker is in place, the postsynaptic membrane potential graph is ________
flat ~ this is evidence that calcium is necessary for transmitter release, without it there's no response in the postsynaptic cell
181
Many naturally occurring toxins such as ________ & ________ are calcium channel blockers
funnel web spider toxin (agatoxin), cone snail (conotoxin)
182
Lyrica is a drug designed to block specific calcium channels in pain relay neurons. It is similar to the structure of ______ though it has no impact on those receptors.
GABA
183
When [Ca] is increased, the frequency of ____________ depolarization increases, but the ________ of these events does not increase
spontaneous, size
184
If extracellular calcium is increased are MEPPs affected?
there is basically no effect because extracellular calcium only has an impact if channels are open, and MEPPs are caused by random release of small amounts of transmitter (a single quanta)
185
Docked vesicles define the maximum _________ amount of releasable vesicles available when an __________ arrives.
potential, action potential
* any vesicles undocked when an AP arrives don't have time to get to the membrane and release
186
the number of immediately releasable vesicles is always _________ the number of docked vesicles
less than or equal to
187
Triskelion protein that binds to vesicle membrane (forms coat) __________
Protein that pinches of membrane in a ring _________
Clathrin, dynamin
188
3 molecules are core of SNARE complex that primes vesicles for release, *1 associates with core but is not part of the complex
1. synaptobrevin
2. SNAP 25
3. syntaxin
*1. Synaptotagmin
189
Vesicles are brought to presynaptic membrane by _________ of SNARE helices (non-fused, docked), PRIMING then requires ____. Final fusion step requires ___.
zippering, ATP, calcium
190
ATP is required for 3 functions in transmitter release:
ATP is NOT required for *_________
1. fill vesicles
2. finish off exocytosis
3. prepare vesicle for recycling
*triggering release
191
Botulinin toxin (botox) affects _______ proteins involved in vesicle fusion
SNARE
*this is why it kills people
192
Docked vesicles are arranged in an ___________ and colocalized with _____________ and other proteins needed for release
"active zone", calcium channels
193
What calcium channel type is used by auditory hair cells?
CaV1.3
*they are activated sooner in depolarization than CaV1.2 channels
194
Dense core vesicles (DCVs) are replenished at the _______ and mobilized to the membrane by continuous elevation of internal ________
soma, calcium
195
DCVs are not clustered at the membrane and have no __________, they are released in all directions. __________ are stored in large DCVs/granules
Active zone, neuropeptides
196
Small molecules packaged in _________________
Neuropeptides packaged in __________________
small clear core vesicles, large dense core vesicles
197
3 factors relating postsynaptic response to release event
| (variables in an equation)
1. k (size of quantal response)
2. p (probability of a vesicle releasing)
3. n (number of potentially releasable vesicles)
~P* is the product of (nxp), release is approx = k x P*
198
_________________ refers to the decrease in strength of connection at a particular synapse
synaptic depression
199
sensitization is a _____________ term, not necessarily a defining term for ______________
behavioural, cellular change
*and cellular change doesn't exactly mean sensitization
200
In crayfish neuromuscular junctions, the active zones have _______ probability of release, thus a ______ epsp will _______ a lot
low, small, facilitate
201
presynaptic activity-dependant facilitation persists for about:
1 second
202
Synaptic facilitation is the rapid increase in synaptic strength that occurs when:
| ~temporal summation
2 or more APs invade the presynaptic terminal within a few milliseconds of each other
203
Post tetanic potentiation
train of high frequency stimuli followed by enhancement lasting several minutes
| enhancement:presyn APs that occur 1-2 mins after tetanus release more NT
204
Increase in p would lead to
more release
205
Increase in n would lead to
more release
206
At frog neuromuscular junction, _________ is causes by ________ in n
depression, reduction
207
Facilitation is almost certainly due to
increase in p (of already docked vesicles)
208
Augmentation and post-tetanic potentiation is due to
Increased P* (increase in p for sure, n in some cases)
209
Aplysia gill-withdrawal affect demonstrates
dishabituation
~ response to siphon touch decreases with each repetition until tail shock/siphon combo
210
Why does tail shock impact gill-withdrawal response?
Tail nociceptors are connected to modulatory interneuron that synapses onto & excites siphon sensory neuron at presynaptic terminal = motor neuron activation in gills
211
What are the cellular changes responsible for short term behavioural facilitation?
- post translational changes of K channel (phosphorylation = slower repol)
= increased release from sensory nerve presyn terminal
212
release is proportional to nxp, p is increased by _________
increasing Ca2+ influx
213
How does short term become long term sensitization?
| 6 points
1. multiple shocks = sustained PKA activation
2. this phosphorylates (activates) CREB
3. CREs are activated that regulates DNA
4. CREB gene regulation creates ubiquitin hydroxylase
5. ub hydro. removed regulatory subunits of PKA
6. CREB stimulates genes to grow new terminals & increase # of synapses
| *PKA is enzyme that phos. CREB
214
What does CREB do
regulates the expression of genes
215
Ubiquitin hydroxylase removes _________ subunit from _____ resulting in ___________
regulatory, PKA, persistent PKA
216
Short term sensitization is defined by
post translational modifications to pre existing proteins
217
Long term sensitization is defined by
- changes in gene expression
- new protein synthesis
- possible growth of new synapses
218
During habituation transmission at the glutaminergic synapse is ______________, this is thought to be the cause of __________ gill contraction response to siphon stimuli
depressed, decrease
219
Short term depression is due to
reduction in the amount of vesicles available for release
220
Short term sensitization seen after the tail shock is due to recruitment of additional circuit elements, namely:
modulatory interneurons
221
Net effect of PKA is to
reduce probability of K channels opening, which prolongs presyn AP, opening more Ca2+ channels, finally increasing amount of transmitter released on motor neurons (gill moves)
