Unit 2 Week 4 Flashcards
What is learning?
acquisition of new knowledge or skills
What is memory?
retention of learned information
What are the two broad categories of memory?
Declarative (explicit)
-memory of facts and events
Nondeclarative (implicit)
-memory for skills, habits and others that don’t have a conscious component
Describe the flow of sensory information into long-term memory
sensory experience, memory acquisition, short-term memory, memory consolidation, long-term memory
Where is memory stored in neural circuits?
Distributed Memory Storage: a neural network model
-unique pattern or ratio of neuronal activity
-distributed memory
-no single neuron represents specific memory
What is the cellular basis of memory?
modification of synaptic strengths that change the input-output relations of neurons within neural circuits
Where do memories reside?
in synaptic modification
What is synaptic pasticity?
describe changes in the strengths of synaptic connections in response to experience and neuronal activity
What is synaptic strengthening?
-synaptic potentiation
-formation of new synapses
What is synaptic weakening?
-synaptic depression
-elimination of exiting synapses
What is the Hippocampus?
a brain region that is important for memory formation
What is LTP?
Long Term Potentiation
A long-lasting increase of the effectiveness of synaptic transmission
Shown by increased EPSP amplitude
What is Hebb’s rule?
synaptic potentiation results when presynaptic activity correlated with strong activation of the postsynaptic neuron
What does NMDA receptor activation depend on?
both glutamate and voltage
-Mg2+ blocks the channel at certain negative Vm, even if glutamate binds
-Need depolarization and glutamate for activation and let in lots of Ca2+
What does the NMDA receptor act as?
coincidence detector
-Ca2+ entry through NMDA receptor specifically signals presynaptic and postsynaptic neurons are active at the same time
What are the mechanisms of LTP in CA1?
Ca2+ through NMDA receptors activate protein kinases (CaMKII)
Achieve LTP by:
1. increasing the effectiveness of existing AMPA receptors on the membrane via phosphorylation of CaMKII
2. inserting new AMPA receptors into the membrane
What is the BCM theory?
An extension of Hebb’s rule…
Synaptic depression results when presynaptic activity is correlated with a weak depolarization of a postsynaptic neuron
What is LTD?
Long-Term Despression
What is the mechanism of LTD in CA1?
-increase protein phosphatase activity
-de-phosophorylate AMPA receptors on the membrane
-remove existing AMPA receptors
What is the difference between LTD and LTP?
opposite change of AMPA receptors
What accounts for bidirectional synaptic changes?
When the postsynaptic cell is weakly depolarized by other inputs: active synapses undergo LTP instead of LTP
Bidirectional plasticity is governed by two simple rules. What are they?
Synapses during strong depolarization of postsynaptic neuron causes LTP (Hebb’s rule)
Synapses during weak depolarization of postsynaptic neuron causes LTD (BCM theory)
Describe memory consolidation
Phosphorylation insufficient as long-term memory consolidation mechanism
-phosphorylation of a protein is not permanent
-memories would be erased
Protein molecules themselves are not permanent
Describe the regulation of CaMKII
-once activated, autophosphorylation will keep kinases stay “on” permanently
-which may hold LTP and memory for a long time
Describe how protein synthesis relations to memory consolidation
-new protein synthesis required during the period of memory consolidation and for formation of long-term memory
What is CREB? Why is it relevant?
cyclic AMP response element binding protein (a transcription factor)
-bind to cAMP response elements (CREs) to regulate expression of specific genes, which ultimately leads to new protein synthesis
Describe the regulation of gene expression by CREB
CREB-2: a repressor of gene expression
CREB-1: an activator of gene expression
What is synaptic remodeling?
formation of new synapses during learning or memory and demolition of old synapses during learning and memory
What are Channelrehodopsins (ChRs):
- a subfamily of light-gated cation channels
-they serve as sensory photoreceptors in unicellular green algae, controlled phototaxis
What is Halordopsin?
-a yellow-light-activated Cl- pump, found in archaea
-to move chloride ions into the cell, reducing the membrane potential
What can optogenetics be used for?
to control neural activity with light
positive ions = neuron activation
negative ions = neuron inhibition
What happens to the brain during sleep?
the brain is “disconnected” from both input and output ends
What is the Electroencephalogram (EEG)?
-measurement of generalized activity of cerebral cortex
-helps diagnose neurological conditions, such as epilepsy and sleep disorders, and for research
How are large EEG signals activated?
synchronous acitivy
What are the three functional brain states in humans?
awake
REM sleep (rapid eye movement)
Non-REM sleep (slow-wave)
What type of sleep is known as paradoxical sleep? Why?
REM sleep, EEG of REM sleep is very similar to EEG of an awake state
What is happening during non-REM sleep?
an idling brain with moveable body, also called slow-wave sleep
What is happening during REM sleeo?
an active, hallucinating brain with a paralyzed body, where dreams occur
What are the Sleep promoting neurons?
acetylcholine in the midbrain/pons
What do GABAergic neurons in the preoptic area (POA) promote?
sleep
What activates GABAergic POA neurons?
ChR2
What do neuropeptide hypocretin (Hcrt) and Hcrt neurons promote?
wakefulness
What causes narcolepsy?
mutations of Hcrt
What are the sleep-promoting factors?
Adenosine: released by neurons; may have inhibitory effects of diffuse modulatory systems
Nitric Acid (NO): triggers release of adenosine
Muramyl Dipeptide: isolated from the CSF of sleep-deprived goats, facilitates non-REM sleep
Interleukin-1 (cytokine): synthesized in brain, stimulates immune system, induces fatigue and sleepiness
Melatonin: released at night, inhibited during daylight; helps initiate and maintain sleep- used to treat symptoms of jet lag and insomnia
What is the broad behavioral definition of sleep?
Sleep is readily reversible quiescence state that is associated with reduced responsiveness to the environment and under homeostatic control
Why do we sleep?
Restoration
-sleep to rest and recover and prepare for when we wake again
- conserve energy, repair and clear metabolic
waste in the brain, facilitate memory and
synaptic plasticity
Adaptation
-sleep to keep out of trouble, hide from predators
