MCB 461 FINAL EXAM | 111 QUESTIONS | WITH
PASSED SOLUTIONS!!
How does binocular vision develop before birth? Answer - Thalamic inputs
representing the left and right eyes segregate from each other to form "ocular
dominance" columns of roughly equal width in the visual cortex
How does binocular vision develop soon after birth? Answer - During the
critical period, the visual experience shapes and combines the representations
of the 2 eyes in the cortex to make binocular vision possible
Normal binocular vision consolidates and refines the established patterns of
ocular representation
Depends on correlated patterns of activity from 2 eyes and convergence of
inputs from Layer IV to III
What happens if you perform monocular deprivation during the critical period?
Answer - The LGN axons from the deprived eye in layer 4 will shrink and
decrease in synaptic strength, whereas axons from the non-deprived eye
expand and increase in synaptic strength
What happens if you reinstate normal vision during monocular deprivatioN?
Answer - This does not readily restore normal binocular responses in the
cortex.
The non deprived eye continues to dominate the responses of cortical neurons
(even up to 5 years)
,A critical period of binocular vision Answer - A "critical period" to establish
binocular receptor fields
Effects of disruptions of binocular vision are IRREVERSIBLE when they occur in
the critical period. In cats, this begins rapidly at 3 weeks. After 6 weeks, this
period gradually closes.
What are some mechanisms of binocular plasticity? Answer - Modulation of
LGN axons that project to layer 4
Adjust synaptic drive by the left and right eyes (NMDA receptor activation)
Mechanisms that contribute to synapse formation or stabilization (BDNF,
neuromodulators—acetylcholine, norepinephrine)
PirB or Nogo and its receptors
Precise balance between excitatory and inhibitory inputs
Critical period is delayed in GABAA receptor knock out mice
Dark rearing prolongs the critical period
Hebbian plasticity Answer - Persistent activation of a group of simultaneously
active neurons would lead to consolidation of stronger connection
In response to extrinsic stimuli, neurons can change and adapt the strength of
their connections. Examples are long term potentiation (LTP) and long term
depression (LTD)
Hebbian Plasticity is Answer - Associative
Rapidly induced
Input specific
Positive feedback process
Physiological relevance
Cellular correlate of "learning and memory"
, Where does Hebbian synaptic plasticity happen? Answer - The HIPPOCAMPUS
LTP and LTD are key to forming declarative memories in the brain
Pathway from entorhinal cortex Answer - Goes from pyramidal cells in the
dentate gyrus to pyramidal cells in CA3 to pyramidal cells in CA1
Synaptic plasticity in the hippocampus is the key to forming Answer -
Declarative memories in the brain
LTP happens at glutamatergic synapses in hippocampus: discovered by Answer
- Bliss and Lomo
Dark circles: POTENTIATED, and their amplitude is higher
In the hippocampus, the EPSP magnitude __________during LTP Answer -
Increases
In the hippocampus, the EPSP magnitude _____________ during LTD Answer -
Decreases
What's the problem with Hebbian platicity Answer - Eventually, persistently
activating neuronal networks would reach an extreme and become unstable
Homeostatic plasticity Answer - Rapid or prolonged process to maintain
neuronal firing and synaptic strength *within physiological limit*, thereby
preventing un-restrained increases or decreases in neuronal activity
How does homeostatic plasticity work Answer - Induced rapidly or in a long
term
PASSED SOLUTIONS!!
How does binocular vision develop before birth? Answer - Thalamic inputs
representing the left and right eyes segregate from each other to form "ocular
dominance" columns of roughly equal width in the visual cortex
How does binocular vision develop soon after birth? Answer - During the
critical period, the visual experience shapes and combines the representations
of the 2 eyes in the cortex to make binocular vision possible
Normal binocular vision consolidates and refines the established patterns of
ocular representation
Depends on correlated patterns of activity from 2 eyes and convergence of
inputs from Layer IV to III
What happens if you perform monocular deprivation during the critical period?
Answer - The LGN axons from the deprived eye in layer 4 will shrink and
decrease in synaptic strength, whereas axons from the non-deprived eye
expand and increase in synaptic strength
What happens if you reinstate normal vision during monocular deprivatioN?
Answer - This does not readily restore normal binocular responses in the
cortex.
The non deprived eye continues to dominate the responses of cortical neurons
(even up to 5 years)
,A critical period of binocular vision Answer - A "critical period" to establish
binocular receptor fields
Effects of disruptions of binocular vision are IRREVERSIBLE when they occur in
the critical period. In cats, this begins rapidly at 3 weeks. After 6 weeks, this
period gradually closes.
What are some mechanisms of binocular plasticity? Answer - Modulation of
LGN axons that project to layer 4
Adjust synaptic drive by the left and right eyes (NMDA receptor activation)
Mechanisms that contribute to synapse formation or stabilization (BDNF,
neuromodulators—acetylcholine, norepinephrine)
PirB or Nogo and its receptors
Precise balance between excitatory and inhibitory inputs
Critical period is delayed in GABAA receptor knock out mice
Dark rearing prolongs the critical period
Hebbian plasticity Answer - Persistent activation of a group of simultaneously
active neurons would lead to consolidation of stronger connection
In response to extrinsic stimuli, neurons can change and adapt the strength of
their connections. Examples are long term potentiation (LTP) and long term
depression (LTD)
Hebbian Plasticity is Answer - Associative
Rapidly induced
Input specific
Positive feedback process
Physiological relevance
Cellular correlate of "learning and memory"
, Where does Hebbian synaptic plasticity happen? Answer - The HIPPOCAMPUS
LTP and LTD are key to forming declarative memories in the brain
Pathway from entorhinal cortex Answer - Goes from pyramidal cells in the
dentate gyrus to pyramidal cells in CA3 to pyramidal cells in CA1
Synaptic plasticity in the hippocampus is the key to forming Answer -
Declarative memories in the brain
LTP happens at glutamatergic synapses in hippocampus: discovered by Answer
- Bliss and Lomo
Dark circles: POTENTIATED, and their amplitude is higher
In the hippocampus, the EPSP magnitude __________during LTP Answer -
Increases
In the hippocampus, the EPSP magnitude _____________ during LTD Answer -
Decreases
What's the problem with Hebbian platicity Answer - Eventually, persistently
activating neuronal networks would reach an extreme and become unstable
Homeostatic plasticity Answer - Rapid or prolonged process to maintain
neuronal firing and synaptic strength *within physiological limit*, thereby
preventing un-restrained increases or decreases in neuronal activity
How does homeostatic plasticity work Answer - Induced rapidly or in a long
term
