Neuroplasticity

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 Ca
2+
(due to
inactivation of Ca
2+
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!