Short-Term Synaptic Plasticity
What form of synaptic plasticty occurs when 2 or more action potentials invade a presynaptic terminal within a few msec of each other?
paired-pulse facilitation
Long-term synaptic plasticity is thought to underlie what behavior? It has been most thoroughly studied in which brain region?
Learning and Memory!!!! The hippocampus.
Which lobe of the cerebral hemispheres is associated with sensation?
What is the parietal lobe?
What is the most common cutaneous mechanoreceptors found in the hand?
What are the Meissner Corpuscles?
Each dermatome innervates a discrete area of skin and does not overlap with other dermatomes.
FALSE
How long does post-tetanic potentiation last? How is it induced?
several minutes, by high frequency stimulation (100 Hz)
What is LTP and how long can it last?
LTP (long term potentiation) is an enhancement of synaptic efficacy / increased sensitivity of the postsynaptic membrane to glutamate, because there is an increase in the number of AMPARs in the postsynaptic membrane. LTP can last for hours, days, weeks, or evens years!
Which component of the diencephalon is the main RELAY center for information to the cerebral cortex?
What is the thalamus?
Where are the cell bodies of the sensory afferents located? And where do they enter the spinal cord?
Dorsal root ganglion (DRG), dorsal roots into the dorsal horn.
Golgi tendon organs are most sensitive to changes in muscle tension.
TRUE
In Aplysia, what occurs with repeated stimulation of the siphon? WHY?
Habituation occurs, in which the gill withdrawal response gets progressively weaker with repeated stimulation. This occurs because there is a decrease in glutamate released by the sensory neurons onto the motor neuron innervating the gill muscle.
Which type of receptor is critical for the induction of hippocampal LTP?
NMDA receptors (if you block NMDARs, LTP will not develop).
The cerebral hemispheres communicate with one another through which structure?
What is the corpus callosum?
Which type of sensory fibers conduct the fastest? which are the slowest?
Ia sensory affarents (largest diameter), C fibers (smallest and are unmyelinated!)
A receptor potential is usually due to activation of voltage-gated ion channels.
FALSE
Which ion plays a central role in most of the forms of synaptic plasticity that we studied?
CALCIUM!
What are silent synapses? How are they converted into active synapses?
Silent synapses have NMDA receptors but do not have AMPA receptors. Following LTP, silent synapses will transmit robust responses due to the addition of AMPA receptors in the postsynaptic membrane.
What is the major landmark of the cerebral hemispheres that divides the temporal lobe from the frontal lobe?
The lateral (Sylvian) fissure
When looking at the primary somatic sensory cortex, why are some areas of the body disproportionally represented?
The density of receptors is much greater in some regions of the body, especially the hands and face.
The strength of synapses can be adjusted by modulating the amount of neurotransmitter that is released.
TRUE
Which cellular mechanism is required for long-term enhancement of the gill-withdrawal reflex in Aplysia?
Long-term sensitization, which induces phosphorylation of CREB by PKA. Activated CREB increases protein synthesis of ubiquitin hydrolase, which degrades the regulatory subunit of PKA and leads to persistent PKA. (also see increase in synaptic growth)
LTP and LTD in the hippocampus both require the increase of calcium through NMDA receptors? What determines which form of synaptic plasticity occurs?
LTD occurs when Schaffer collaterals are stimulated at low frequencies (1 Hz) for long periods of time. This produces a SLOW and small increase in Ca. LTP on the other hand occurs when the Schaffer collaterals are stimulated by high frequency stimulation (100 Hz), which produces a LARGE fast increase in Ca levels.
What is the meningeal membrane that is closest to the nervous tissue?
What is the Pia Mater?
What is proprioception? Name three kinds of proprioceptors.
Proprioception gives continuous information about the position of the limbs and body in space. Three types of proprioceptors include muscle spindles, golgi-tendon organs, and joint receptors.
If one synapse (A) is very strongly stimulated (sufficient to cause LTP), and another nearby synapse (B) on the same dendrite is weakly stimulated at the same time, then the second synapse (B) will also show LTP.
TRUE (it is called associativity)