block 4 synapses

Question 1

why is synaptic integration important?

Answer 1

-Neurons make contact with
multiple neurons and receive
100-1000s of synaptic inputs
-synaptic integration enables
information processing in the
CNS
-integration of synaptic inputs
determines nervous system
function.
therefore synpases and there contacts are important because of the complexity of the neurone, and their ability to reach 100’s of neurones

Question 2

two aspects of synaptic integration

Answer 2

-single EPSP=
-spatial integration
-temporal intergration = find out what this is!

Question 3

parameters that effect synaptic integration

Answer 3

• Neuronal morphology and synapse distribution
• Complexity of neuritic processes
• Distance of synapses to soma and to each other
• Synaptic properties
• Amplitude of current flow at synapse
• most single synapses only produce relative modest
  postsynaptic membrane potential changes
  (~ 1-2 mV at the soma)  multiple synaptic inputs are
  required to depolarise neuron sufficiently to trigger action
  potential
• Membrane properties
• Length constant affects spatial summation
• Time constant affects temporal summation
  -rewatch this part of the lecture

Question 4

spatial synaptic integration

Answer 4

distal axon. one neuron-multiple contact sites?
Presynaptic action
potential activates
multiple synaptic
contact sites
simultaneously
Many neurons -
simultaneous activity
Activity in more than one
presynaptic neuron
coincides
 multiple synaptic
contact sites are activated
simultaneously
 Total effect on soma membrane
potential is sum of all synaptic
potentials

Question 5

purkinje cells= intergrators in the cerebellum

Answer 5

Receives two principal types
of inputs:
* Climbing fibre: one climbing
fibre per Purkinje cell, each
climbing fibre forms many
synaptic contacts with
Purkinje cell
* Parallel fibre: each Purkinje
cell receives synaptic inputs
from thousands of parallel
fibres, single synaptic contact
site between one Parallel
fibre and Purkinje cell

Question 6

purkinjie cells-two types of synaptic inputs

Answer 6

Parallel fibre input:
Single contact
- small synaptic
current & potential
Climbing fibre input:
Many contacts
- large synaptic current & potential,
-triggers complex spike

Question 7

spatial synaptic intergration and length constant

Answer 7

naptic potentials spread passively from site of synapse
 Amplitude of synaptic potential change reduces with distance
from synapse
 Decline in synaptic amplitude with distance from synapse is
determined by length constant

x
EPSPm eVV

 max
* Synaptic potential decline is
described by length constant 
(lambda) and the exponential
function: