Neuronal Integration

Question 1

Divergence (Axon)

Answer 1

Axon from single neuron branches many times, forming synaptic contact with multiple target cells.

Question 2

Convergence (Axon)

Answer 2

Single cell receives input from many presynaptic neurons. Allows integration of many sources of information

Question 3

Types of inhibitory circuits

Answer 3

1) presynaptic inhibition
2) disinhibition
3) lateral inhibition
4) feedback inhibition
5) feedforward inhibition

Question 4

Disinhibition

Answer 4

Inhibition of an inhibitory neuron. Can be postsynaptic or presynaptic

Question 5

Lateral Inhibition

Answer 5

Interneurons create inhibitory receptive field adjacent to excitatory receptive field

Question 6

Reverberating Circuit

Answer 6

Constructed from feedforward and feedback excitatory connections. Allow for persistent activity in a system. Can allow a response to outlast a stimulus and information to be stored (as a short-term memory)

Question 7

What type of neural circuit in the brain can cause seizures?

Answer 7

Runaway excitation in reverberating circuits in the brain can cause seizures. Local feedback inhibitory connections normally prevent runaway excitation.

Question 8

Central Pattern Generators

Answer 8

Rhythmically alternating activity can be created by several types of neural circuits. For example, reciprocal inhibitory connections

Question 9

Elements of Information Encoding (in order)

Answer 9

1) input zone
2) integration (trigger) zone
3) conduction zone
4) output zone

Question 10

At this stage of encoding signals consist of graded potentials

Answer 10

input zone

Question 11

Graded potentials are converted to all-or-none potentials (action potentials) at this stage. Signal strength becomes encoded by frequency modulation

Answer 11

Integration zone (or trigger zone)

Question 12

Ion channels playing a role in integration zone

Answer 12

1) HVA Calcium Channels
2) LVA Calcium Channels
3) Ca-Activated Potassium Channels

Question 13

Integration zone ‘burst firing’

Answer 13

If integration zone contains LVA Voltage-Gated Calcium channels, burst firing can occur if the neuron is hyperpolarized from the normal resting potential long enough to remove inactivation.

LVA channels open below action potential threshold and inactivate rapidly

Question 14

Some seziure disorder involve abnormal, rhythmic, self-sustaining activity driven by _____ channels

Answer 14

T-type (LVA calcium) channels

Question 15

Ethosuximide

Answer 15

an inhibitor of T-type calcium channels is effective for some patients with absence seizures