Presentation slide on Neuroplasticity. Prepa

1. Neuroplasticity
Presented By:
Bikram Adhikari
Roll no. : 3
Human Biology
Bikram Adhitya Adhikari

2. Introduction
• Plasticity – the ability to be
moulded /shaped (from Greek
”plastos” )
• "Neuroplasticity" introduced by:
– William James (1842-1910)
– American psychologist and
philosopher
– brain functions are not fixed
throughout life (Principles of
Psychology 1890)

3. Introduction
• Neuroplasticity is the ability of the brain to
change, for better or for worse, throughout
the individual’s life span
• Prominent during development
• Adult brain must also possess substantial
plasticity to:
– Learn new skills
– Establish new memories
– Respond to injury throughout life

4. Positive outcomes
• New skills
• Better cognition
• More efficient communication between
sensory and motor pathways
• Improved function of the aging brain
• Slowing down pathological processes
• Promoting recovery of sensory losses
• Improved motor control
• Improved memory
(Mahncke, Bronstone & Merzenich, 2006; Mahucke & Merzenich, 2006; Nudo 2007; Stein & Hoffman, 2003).

5. Negative outcomes
• Decline in brain function
• Altered motor control
• Impaired performance of activities of daily
living
• Amplified perception of pain
(Mahncke, Bronstone & Merzenich, 2006; Mahucke & Merzenich, 2006; Nudo 2007; Stein & Hoffman, 2003).

6. Types of Neuroplasticity
• Structural Neuroplasticity
• Functional Neuroplasticity

7. Structural Neuroplasticity
• Synaptic plasticity
• Synaptogenesis
• Neuronal migration
• Neurogenesis
• Neural cell death

8. Functional Neuroplasticity
• Depends upon two basic processes,
learning and memory
• They also represent a special type of
neural and synaptic plasticity

9. Synaptic Plasticity
• Synaptic plasticity refers to changes in the
strength of connections between synapses
• It can be:
– Short Term Synaptic Plasticity
– Long Term Synaptic Plasticity

10. Short Term Synaptic Plasticity
(Katz, 1966.)
• Last for minutes or less
Properties:
• Synaptic Facilitation
• Synaptic Depression
• Post-tetanic Potentiation

11. Short Term Synaptic Plasticity
• While these mechanisms are probably
responsible for many short-lived changes
in brain circuitry
• They cannot provide the basis for
memories or other manifestations of
behavioral plasticity that persist for weeks,
months, or years.

12. Learning and Memory
• Learning:Acquisition of information
• Memory:
– Storage of that information
– may be short term or long term memory

13. Synaptic plasticity and Learning
• Habituation:
– A simple form of learning in which a neutral
stimulus is repeated many times.
– Associated with decreased release of
neurotransmitter from the presynaptic terminal
because of decreased intracellular Ca2+
(due to
inactivation of Ca2+
Channel

14. Synaptic plasticity and Learning
• Sensitization
– The prolonged occurrence of augmented
postsynaptic responses after a stimulus to
which one has become habituated is paired
once or several times with a noxious stimulus
– Sensitization may occur as a transient
response, or if it is reinforced by additional
pairings of the noxious stimulus and the initial
stimulus, it can exhibit features of short-term
or long-term memory

15. Long Term Synaptic Plasticity
• Long-term potentiation (LTP):
– patterns of synaptic activity in the CNS
produce a long-lasting increase in synaptic
strength
• Long-term depression (LTD):
– patterns of activity produce a long-lasting
decrease in synaptic strength

16. Long Term Potentiation
• Resembles post-tetanic potentiation but is
much more prolonged and can last for
days
• LTP occurs at excitatory synapse in:
– Hippocampus
– Cortex
– Amygdala
– Cerebellum

17. Properties of LTP
C) State dependent

18. Mechanism of LTP

19. Long term Depression
• LTD is the opposite of LTP
• It resembles LTP in many ways, but it is
characterized by a decrease in synaptic
strength
• It may be involved in the mechanism by
which learning occurs in the cerebellum

20. Mechanism for LTD in
Hippocampus

21. Plasticity in the Adult
Cerebral Cortex
• New research reveals that many aspects of the brain
remain plastic in adulthood via animal studies
• If a digit is amputated in a monkey, the cortical
representation of the neighboring digits spreads into the
cortical area that was formerly occupied by the
representation of the amputated digit
• Conversely, if the cortical area representing a digit is
removed, the somatosensory map of the digit moves to
the surrounding cortex

22. Plasticity in the Adult
Cerebral Cortex
• Long-term deafferentation of limbs --> dramatic shifts in
somatosensory representation in the cortex
• PET scanning in humans also documents plastic
changes from one sensory modality to another
– Tactile and auditory stimuli increase metabolic activity in the
visual cortex in blind individuals
– Deaf individuals respond faster and more accurately than
normal individuals to moving stimuli in the visual periphery

23. References
• Purves D. et al. Neuroscience.3rd edition.
2004.chapter 24.
• Barret K. et al. Ganong's Review of
Medical Physiology.23rd
edition.McGrawHill
• VIDA D. SANDRA M. RAPHAEL B.
Review literature on Neuroplasticity. 2014
PERIODICUM BIOLOGORUM.116; 2:
209–211

24. Thank You!