learning and memory neuroscience

1. Learning & Memory

2. Learning
• According to Eric Kandel “Learning is a process
by which we acquire knowledge about the
world”
• Kimble “Learning refers to more or less
permanent change in behaviour which occurs
as a result of practice”

3. • Further definition says, “Learning is either a
case of differential strengthening of one from
a number of responses evoked by a situation
of need or formation of receptor evoked
connections”

4. What is Memory ?
• According to Kandel “Memory is a process by
which that knowledge of the world is encoded,
stored and later retrieved”

5. Types of Memory
Explicit
Episodic Semantic
Implicit
Associative
Classical
eg: pavlov’s
experiment
Operant
Eg:
Pigeon
pecks a
key
Non-
associative
Habituation
Eg: Dog
aroused by
tone played
Sensitization
Eg: dog
reacts to less
tone

8. • Different forms of learning are affected
differentially by lesions in different locations
Defects in memory storage
for object recognition

9. • Hippocampal system does initial steps in long
term memory storage
• Memories of single event can be stored in
multiple locations
• Each new explicit memory is formed by 4
sequential processes
a) Encoding
b) Consolidation
c) Storage
d) Retrieval

10. Implicit Memory
• They are stored differently on how they are
acquired
• Operant conditioning involves the straitum
and cerebellum
• Classical, sensitization and habituation
involves sensory and motor systems

11. Processes of Learning
• Donald Hebb stated, “when a axon of cell A
excites cell B and repeatedly or persistently
takes part in firing it, some growth process of
metabolic changes take place in one or both
cells so that A’s efficiency as one of the cells
firing B is increased”

12. Habituation
•What happens in
nervous
system to produce
habituation?
•Experiments
performed in Aplysia
californica, the sea
slug, were designed
to address this
problem

14. Sensitization

15. 1
• Axonic syanpse occurs
• Serotonin (5 hydroxytryptamine) is released by pre and post synaptic
axon
• Activates G protein
• Adenyl cyclase
2
• cAMP Produced
• Activates cAMP dependent kinase
• Close k channels
• Opens ca channels
3
• Activation of 5HT pathway by tail stimulation , therefore causes more
substance to be released by siphon stimulation
• Leads to response by gills

17. • Short term tail stimulation
• Long term tail stimulation
• Structural changes occur in pre synaptic
terminals

18. Long term potentiation
• Hippocampus is important storage for
declarative memory
• High frequency train of stimuli applied to
fibers afferent to hippocampus increase
amplitude of EPSPs in target neuron
• Pre and post synaptic cells both be active at
same time

19. Experimental set up for demonstrating LTP
Made
Stimuli applied
Amplitudes
Of post synaptic
Potentials
For single stimulus
Hebbs rule at work

20. Glutamate binds to metabotropic receptor, activating PLC and to NMDA
receptors
NMDA can bind glutamate but no current will flow through the channels
unless Mg++
Is displaced

21. High frequency stimulation opens glutamate Non NMDA channels leading to
hypopolarization.
This dislodges Mg++ , Ca++ enters the cell. Calcium triggers activity of Ca dependent
kinases.
Calcium calmodulin kinase phosphorylates non NMDA channels increasing their
sensitivity
To glutamate and a messenger is sent to presyanptic terminal to increase the
release of transmitter substance

22. References
• Learning and Memory http://michaeldmann.net/mann18.html
• Neurobiology linster
http://www.nbb.cornell.edu/
• Learning and Memory by John H. Byrne, Ph.D., Department of Neurobiology
and Anatomy, The UT Medical School at Houston
http://neuroscience.uth.tmc.edu/s4/chapter07.html