developmental synaptic plasticity and cortical dominance columns

Question 1

what does synaptic plasticity make precise?

Answer 1

topographic maps

Question 2

what is APV?

Answer 2

drug that blocks NMDA receptors

Question 3

what receptors mediate synaptic plasticity?

Answer 3

NMDA

Question 4

what is an ocular dominance column?

Answer 4

functional groups of neurons in the primary visual cortex that respond preferentially to input from one eye or the other
pattern of ocular dominance typically shows alternating stripes of neurons
e.g ipsi, contra, ipsi)

Question 5

hubel and wiesel experiment (1)

Answer 5

inject radioactive proline (amino acid) in the early stages of development of kitten
leave it for 10 days
creates white stripes (radioactivity)
shows input from one eye is going to particular area (ocular column)

Question 6

hubel and wiesel experiment (2)

Answer 6

stitch up one eye and inject proline into the other
white stripes get broader- more input to cortex from opened eye as there is more activity

Question 7

critical period- hubel and wiesel

Answer 7

if you stitch up eye in adult cat, there is no plasticity

Question 8

TTX in eyes

Answer 8

block activity in the eye as they are sodium channel blockers meaning you dont get plasticity

Question 9

APV into cortex

Answer 9

prevents ocular dominance column plasticity

Question 10

barrel cortex and dominance columns

Answer 10

column of activity in somatosensory cortex that corresponds to each whisker on whisker pad- created grid in layer 4 of cortex

Question 11

whisker deprivation

Answer 11

cut whisker in critical period
when you stimulate whisker, you get activity in corresponding barrel, not other ones
when you stimulate cut whisker, there is no specificty and there is activity in many other barrels

Question 12

D/L-APV injection

Answer 12

L-APV=specificty from one barrel as L-APV is inactive isomer
D-APV=same response as shaved whisker as it is activer isomer

Question 13

hebb’s postulate (associtaive plasticity)

Answer 13

“cells that fire together, wire together”

Question 14

what does hebb’s postulate mean?

Answer 14

when two neurons are activated simultaneously, the synaptic connection between them strengthens
those that are activate simultaneously have weakned synaptic connections

Question 15

NMDA receptors

Answer 15

bind glutamate but wont open
they also need to remove a magnesium ion in their pore
depolarisation=magnesium out and current can flow
=only active when pre and posy-synaptic cell are active, calcium flowing=signal for coincident activity

Question 16

calcium influx through the NMDA receptor can induce long-term synaptic potentiation or depression

Answer 16

basal calcium- nothing
lots of calcium- LTP
little calcium- LTD

Question 17

what happens if you activate post before pre-synaptic?

Answer 17

depression of synaptic weight

Question 18

developmental synaptic plasticity

Answer 18

pairing protocol no longer induces any potentiation (first week of life there is)

Question 19

what happens to plasticity in mice raised in the dark?

Answer 19

extends the critical period as they have had no sensory input