Lecture 8 - Molecular mechanisms of Long-term potentiation, Associative plasticity, & Associative memory

Question 1

What is associativity? (Hebb’s postulate)

Answer 1

Any metabolic changes in cell A can affect nearby cell B

• Hebb’s postulate

Question 2

Associated inputs

How do LTPs form with a weak input (bird) and a strong input (orange) which is further from the cell body?

Answer 2

Associated inputs are stronger due to touch and taste
Orange produced the plasticity proteins because of the strong association
Orange will form late-LTP because of strong input
Bird forms early-LTP which fades after 2-3 hours or a week because no proteins were produced
If bird is associated with orange, proteins produced from orange input are shared with bird to convert short-term memory to long-term memory
Associative memory is time-dependent whether the strong or weak input is first

Question 3

What are the proteins that promote LTP, associativity and long-term memory?

Answer 3

Protein kinase M zeta (PKMζ) - an LTP specific plasticity protein

Brain derived neurotrophic factor (BDNF) - Critical for cross-capture and LTD tagging

Question 4

How are CaMK involved in tagging and PRPs (plasticity-related proteins)?

Answer 4

Synaptic stimulation activates CaMKII and CaMKK (which activates CaMKIV)

CaMKIV is involved in transcription of PRPs using CREB

Hypothesis 1 - CaMKII leads to tagging
Hypothesis 2 - CaMKII leads to tagging and transcription of PRPs