Cellular and molecular LTD

Question 1

Where can we find long-term depression ?

Answer 1

LTD is most intensively studied

in the hippocampus and cerebellum

Question 2

What is required for Hippocampal LTD ?

Answer 2

NMDA receptors

Question 3

What prevents LTD induction?

Answer 3

Introducing inhibitors of calmodulin into the postsynaptic neuron

Question 4

What is required for LTD ?

Answer 4

Protein Phosphatases

Question 5

Hippocampal LTD

contributes to ?

Answer 5

Behavioural flexibility

Question 6

Ca2+ ions entering through

NMDARs bind ?

Answer 6

To CaM

Question 7

The Ca2+/CaM complex activates ?

Answer 7

Protein phosphatases

Question 8

PP2B (a.k.a. Calcineurin) is directly activated by ?

Answer 8

Low nanomolar concentrations of Ca2+/calmodulin

Question 9

PP2A is also required for LTD

although ?

Answer 9

It’s mechanism of activation is not so well understood

Question 10

PP1 and PP2A sustain their

activity by ?

Answer 10

Autocatalysis

Question 11

Activated PP1 dephosphorylates?

Answer 11

GluA1, TARP and PSD-95

Question 12

What does activated PP1 also dephosphorylate ?

Answer 12

GSKβ

Question 13

GSKβ regulates ?

Answer 13

The internalisation of AMPARs by endocytosis

Question 14

Ca2+ flux through NMDA receptor channel determines ?

Answer 14

The sign of plasticity

Question 15

Ca2+ flux through NMDA receptor channel determines?

Answer 15

• LFS is low frequency stimulation (e.g. 1 Hz)
• STDP is Spike Timing Dependent Plasticity
• DHPG is a mGluR agonist

Question 16

Explain the Parallel fibres in the cerebellum ?

Answer 16

• Motor information input travels from the spinal
  cord, cerebral cortex and vestibular system via
  mossy fibers → major pathway of information flow
• Granule cells relay signals to Purkinje cells.
• A single parallel fibre forms 1-5 excitatory synapses
  onto a Purkinje cell dendrite
• Many parallel fibres make synaptic contacts onto a
  single Purkinje cell

Question 17

Explain the Climbing fibres in the cerebellum ?

Answer 17

• A single climbing fibre forms > 300 excitatory
  synapses onto a Purkinje cell
• Arises from neurons in the inferior olivary nucleus.
• When motor information is associated with
  failure, an ‘error’ signal conveyed by the climbing
  fibre weakens the connection between parallel
  fibers and the Purkinje cell that contributed to the
  failed action → achieved by Long-term depression

Question 18

What is the only output of the cerebellar cortex ?

Answer 18

Purkinje cells

Question 19

It is a GABAergic neuron that forms ?

Answer 19

Inhibitory synapses on neurons in a cerebellar and

vestibular nucleus

Question 20

What do Parallel fibre synapse (PFs) activate ?

Answer 20

AMPA and mGluR1 but not IP3 receptors

Question 21

PF and CF synapses

together trigger ?

Answer 21

Activation of IP3R

Question 22

In the PFs, what does Ca2+ activate ?

Answer 22

PKC and phosphorylates GluA2 with the help of PICK1

Question 23

In the PFs, AMPARs with
phosphorylated GluA2
dissociate from ?

Answer 23

GRIP

Question 24

AMPA receptors at the
PF synapse are
internalized by ?

Answer 24

Endocytosis