lecture 23

Question 1

what is the doppler effect

Answer 1

combination of a change in pitch (frequency) and change in loudness (amplitude)

ambulance coming towards you, soundwaves become more compressed.
Frequency goes up. Wavelength gets short

Question 2

how do moths detect sounds

Answer 2

neurons in the moth ears
1. Neuron A1 (lower threshold): firing causes moth to change direction of flight
2. Neuron A2 (higher threshold): neuron responds to intense, very close sounds. causes moth to dive, an erratic, last-minute evasive maneuver

Question 3

What is Eric Kanel do

Answer 3

studied synaptic plasticity in sea slug (Aplysia)

Question 4

what is synaptic plasticity

Answer 4

the ability of synapses to change in efficacy as a function of synaptic activation (stimulation)

Question 5

describe the behaviors in Aplysia that can be modified by experience

Answer 5

1. habituation: diminishing response following repeated stimulation
2. Sensitization: more responsive to a stimulus that previously had no effect

Question 6

describe the habituation and sensitization gill withdrawl reflex in Aplysia

Answer 6

▪ With habituation, fewer Ca2+
channels open in response to
Glutamatergic action potentials in the sensory
neuron. So less neurotransmitters are released

Shocking the tail excites a serotonergic glutamate neuron causing increased glutamate
release and a strong gill withdrawal reflex (Sensitization)

Question 7

What are the functions of the Aplysia body parts

Answer 7

Gills: the primary respiratory organ
Mantle: protects delicate Gills
Siphon: moves water though the animal

Question 8

describe the neural stimualtion of Aplysia

Answer 8

touching the siphon repeatedly without a noxious stimulus habituates the gill withdrawal
reflex.
a tail shock returns the gill withdrawal reflex (strongly).

motor neuron releases serotonin, affects serotonergic sensory neuron on the tail

Question 9

what are the molecular mechanisms of habituation and sensitization

Answer 9

Transmitter release in the sensory terminals decreases with habituation and increases with sensitization.

Question 10

describe how serotonergic interneurons cause sensitization

Answer 10

GPCR acts as a serotonin receptor and activates Gprotein to activate adenylyl cyclase to create cAMP from ATP. cAMP acts on a cAMP-dependent protein kinase (PKA), phosphorylating proteins including a K+ channel.

Decrease in K+ efflux (out) leads to an increase in the duration of action potentials which results in more Ca2+ channels opening.

Ca2+ mobilizes neurotransmitter vesicles. increase in Gill withdrawl reflex

Question 11

describe the subunits of protein kinase a

Answer 11

two subunits form tetrameric protein
catalytic subunit C
regulatory subunit R: with 2cAMP binding sites

binding of 2 cAMP to a subunit (R+C) releases catalytic subunit to phosphorylate

Question 12

describe the result of cAMP activation

Answer 12

cAMP causes dissociation of the two subunits, hence the activation

Question 13

describe induction and maintenance of LTP in the hippocampus-I

Answer 13

in a resting neuron, AMPA and NMDA receptors are closed. MG2+ blocks NMDA

glutamate binds on both receptors
presynaptic stimulation causes Na+ influx through AMPA receptors and depolarizes (epsp)

tetanic stimulation: results in strong depolarization, knocking of Mg2+ from NMDA, allowing CA2+ influx

elevated CA2+ initiates insertion of more AMPA receptors onto the postsynaptic membrane

structural changes of additional AMPA at the membrane of postsynaptic neuron leads to long term potentiation because it makes the neuron more sensitive to a given amount of neurotransmitters=stronger response

Question 14

describe LTP in hippocampus (graph)

Answer 14

synapses in hippoampus shows increase in EPSP amplitude after a repeated strong stimulus. causing a long lasting EPSP increased amplitude

Question 15

how is LTP arificially stimulated in hippocampal neurons

Answer 15

CA3 neurons synapse with CA1 neurons. tetanic stimulation of CA3 neuron induces LTP in CA1 neuron

Question 16

describe integration of inputs in the CNS

Answer 16

Temporal summation: inputs from same neuron (AAA)
bumpy slowly increasing humps on graph

Spatial summation: inputs coming from different neurons (AB)
larger combined stimulus results in a singular larger hump on graph

Question 17

what is tetanic stimulation

Answer 17

a high-frequency sequence of electrical impulses used to repeatedly stimulate a nerve, muscle, or neuron

Question 18

what directly causes increased AMPA receptors on postsynaptic membrane

Answer 18

Increased Ca2+ which causes increased level of

PKC
Ca2+/calmodulin kinase
other kinases

Question 19

describe before and after tetanic stimulation (tetanus)

Answer 19

before, each single test stimulus produces a fairly consistent EPSP size

after the tetanus, the amplitudes of the test EPSPs are increase 200%-300% of control amplitudes

Question 20

what are EPSPs and IPSPs

Answer 20

graded potentials

Question 21

how do EPSP and IPSP graded potentials look on the graph

Answer 21

an excitatory stimulus AAA has multiple increasing jagged bumps, A+B is a single larger stimulus

an inhibitory potential D combined with excitatory potential A of similar size cancel each other out