advanced neurobio exam 1

Quiz 1 1. What determines a neuron’s resting membrane potential? a. The mixed ionic conductances active during membrane depolarization i. Happens during synaptic transmission and doesn’t affect resting membrane potential b. Low-threshold voltage-gated K+ channels which are active at hyperpolarized membrane potentials i. Mostly leak currents that are active that determine resting membrane potential ii. Voltage gated K+ channels open at depolarized states c. The transmembrane concentration difference and permeability to K+ ions d. The high external and low internal concentration difference of K+ ions i. K+ is high internal and low external 2. Which of the following are true statements about the equilibrium potential? a. Equilibrium potential is important for determining the resting membrane potential, but not for knowing how the voltage changes during action potentials i. Equilibrium potential is important for both determining resting membrane potential and for knowing how long voltage changes during action potentials b. Each ion has its own equilibrium potential c. Equilibrium potential depends on the concentration difference across the cell membrane d. Current can flow inward or outward when the voltage is set more positive or negative to the equilibrium potential 3. Find the false statement about the Goldman-Hodgkin-Katz equation. a. Membrane potential can be found by multiplicative combination of the equilibrium potential for each permeant ion i. Found by adding ions b. The essential factors in the GHK equation are permeability and concentration c. Membrane potential can be found by additive combination of the equilibrium potential for each permeant ion d. The GHK equation basically simplifies to the Nernst equation if only one ion is present 4. Why is the ionic driving force important? a. It says that no current will flow if membrane potential is equal to equilibrium potential, even if all of the relevant ion channels are open i. Driving force can be 0 if M (membrane potential) = equilibrium potential, and even if there’s channels open, there will be no net flow bc no driving force b. It determines how much current of that ion will flow, because of the difference between the membrane potential and the equilibrium potential

c. It is part of (at least one form) of Ohm’s law i. Ionic driving force is the difference in membrane potential & equilibrium potential, the V d. It determines how much current of that ion will flow, but only at the most depolarized or hyperpolarized potentials i. Should be able to be defined at any given membrane potential 5. Ohm’s law essentially says: a. Voltage will change depending on the current scaled by the resistance b. Resistance is the opposite of conductance i. Resistance is the inverse of conductance c. The membrane acts like a resistance-capacitance (RC) circuit i. Not even mentioned d. Current will be large at depolarized potentials i. Depends on driving force, and factors that aren’t always true 6. What is the most useful patch clamp recording configuration for measuring the post- synaptic potential (PSP)- the voltage change resulting from synaptic input? a. The whole-cell mode, because the inputs from the entire cell membrane are recorded i. Focuses on whole cell, other two only focus on ion channel or small part b. The outside-out mode, because the inputs to only that ion channel are recorded c. The cell-attached mode, because the inputs to only that small patch of membrane are recorded 7. Related to the O’Brien et al. 2002 paper, which of the following statements are true? a. The influence of a single synaptic input is weaker for a large neuron like the alpha ganglion cell, whereas a single synaptic input is strong for a neuron like the beta ganglion cell i. Need less synaptic input to drive smaller neuron, so it’s weaker for larger neuron b. Rn is directly related to resting membrane potential, that is, cells with lower Rn also have lower Vrest i. Not directly related like this c. Smaller neurons depolarize and spike more to an injected current because they have higher input resistance (Rn) i. Strongly drive beta cell, not as much as alpha d. Smaller neurons depolarize and spike more to an injected current because they have lower input resistance (Rn) i. Not true, smaller have higher input resistance 8. Related to the Hausser 2001 paper, How does a postsynaptic potential (PSP; a voltage change from a synaptic input) to the distal dendrite of a pyramidal neuron reach the soma?

i. Voltage c. Ohm i. Unit of resistance d. pA i. Unit of current e. mV i. resting membrane potential is in mV 3. Single channel currents are in the range of __ a. V b. Ohm c. mV d. pA e. I 4. If a synaptic input depolarizes a neuron by 10 mV, and the neuron has input resistance (Rn) of 100 MOhm, what is the amplitude of the synaptic current? Remember that V=IR. So in this case, 10 mV = I * 100 MOhm. What is I? a. 0.1 A b. 1 c. 0.1 nA i. 10 / 100 = 0.1 nA bc we’re solving for currents (nA) d. 100 mV 5. To record the total synaptic input a neuron receives, use ____ clamp recordings to measure the membrane _____ . a. Current; current i. Measuring membrane voltage when using current clamp recordings b. Outside-out patch; voltage i. Outside out - single channels c. Whole-cell voltage; current i. Total synaptic input = whole cell measurement, d. Cell-attached voltage; current i. More for single line channels 6. Find the true statement a. Na channels, like K channels, do not inactivate when depolarized i. They do inactivate b. K channels activate with a delay compared to Na channels, and stay open longer c. Without voltage-gated K channels, the neurons would not have a resting membrane potential i. Largely carried by leak channels, not voltage gated channels d. K channels are primarily responsible for the ‘upswing’ part of the AP i. Upswing is carried by Na+ channels

7. Find the false statement a. K channels do not inactivate because they do not reach the correct voltage to inactivate i. They do reach a voltage to inactivate b. Actually, all are true c. K channels do not inactivate because they do not have an inactivation gate d. Even if K channels had high permeability at the resting membrane potential, little current would flow i. Equilibrium membrane potential is -80, and resting membrane potential is close (-60). So there would be little driving force e. K channels are responsible for the ‘repolarization’ phase of the AP i. Yas they bring them back down 8. What would happen if Na channels did not inactivate? (choose correct) a. The AP would be shorter in duration b. The AP amplitude would be larger, overshooting way past +40 mV i. Na doesn’t let it go past 40 c. The AP would be longer in duration 9. AP backpropagation describes the phenomenon of (choose correct) a. The active spread of voltage from an axonal AP into the dendrites by voltage- gated channels b. Generation of dendritic plateau potentials i. Can go backwards to trigger plateau potentials but that’s abt it c. The process of AP propagation from the axon hillock to the synapse i. This is forwards 10. Which of the following are important factors for dendrites to generate a dendritic action potential (dAP)? (choose all correct) a. Synaptic input coincident with a backpropagating AP b. Dendritic voltage-gated Ca channels create a large ‘plateau potential’ c. Receiving a very large synaptic input d. The dendrites must be as long as the axon i. Not that long e. Dendritic voltage-gated Na channels create a large ‘plateau potential’ i. It’s K channels not Na Quiz 3 1. NMDA receptors are not capable of producing a plateau potential (similar to dendritic action potentials, dAPs). a. True b. False

7. The Calyx of Held is named that way because of the way the large presynaptic forms a "claw" around the postsynaptic neuron a. True b. False 8. When action potentials are wider (long duration), this increases the amount of neurotransmitter released more than when action potentials are taller (large amplitude). a. True i. APs longer = more neurotransmitter release (width is more important) b. False 9. What is the importance of the Mg2+ block in the NMDA receptor? (choose all correct answers) a. Dendrites are highly sensitive to Mg2+ ions, causing NMDA spikes i. Did not learn b. It acts like a voltage gate because it is removed with depolarization c. It creates a non-linearity in the I-V curve, only allowing the mixed cation current to flow after its removal i. Non linear curve was made d. After being removed, the Mg2+ enters the cell along with Na+, contributing additional current to the postsynaptic response i. Didn’t learn this, but does not happen 10. Find the false answer about long-term potentiation (LTP) a. Synaptic strength can be increased by insertion of new postsynaptic AMPA receptors b. NMDA receptor properties are unchanged after LTP, only AMPA receptors undergo changes i. They do undergo changes c. Postsynaptic Ca2+ entry is important for expression of both LTP and LTD Quiz 4 1. Where do the 10,000 synaptic inputs to a cortical pyramidal cell come from? (choose one answer) a. Mainly from GABAergic interneurons, with a small number of from other cortical regions i. Also a fraction b. From a variety of cortical and subcortical regions, local connections, and interneurons c. Mainly from sensory thalamus, with a small number of inputs from other regions i. Minority of the inputs d. Mainly from local connections, that is, synapses from neighboring neurons i. Some synapses, but not that many

2. Based on the Petreanu et al paper, choose the most accurate statement about their findings: a. Cortical neurons receive inputs from many presynaptic regions that are segregated into zones along the dendritic tree b. Cortical neurons receive inputs from many presynaptic regions that are randomly distributed across the proximal and distal dendritic tree i. Randomly distributed- not really c. Cortical neurons receive inputs from primarily one presynaptic brain area i. Come from multiple areas 3. CRACM uses TTX to block Na+ channels and 4-AP to block K+ channels because (choose all correct answers) a. Without the blockers, it would not be possible to localize the synaptic input to a specific region on the dendrite b. All are correct c. It is important to allow depolarization only at the presynaptic terminal, not the entire stimulated neuron i. Restrict depolarization to not get nonspecific activation d. The blockers allow for isolation of dendritic spikes, which are important for the CRACM method i. Blockers don’t allow for isolation of dendritic spikes 4. Illumination of ChR2 causes ___ of the membrane potential, while NpHR causes ___ of the membrane potential. ChR2 is activated by ___ light and NpHR is activated by ___ light. a. depolarization, hyperpolarization, blue, yellow b. depolarization, hyperpolarization, yellow, blue c. hyperpolarization, depolarization, yellow, blue d. hyperpolarization, depolarization, blue yellow 5. True or false. Sensory input from the thalamus arrives at cortical layer 4 and is sent to layer 2/3 before arriving at layer 5. a. True b. False 6. True or false. Multi-cell patch-clamp recordings measure the locations of synapses along the dendrite. a. True b. False 7. In the cortex, the connection probability of neighboring cortical pyramidal neurons (the chances of finding synapses made between cells) is around: a. 0.2