Below is a diagram of a network of neurons AG and additional

Below is a diagram of a network of neurons A-G, and additional inputs (X-Y) to provide some additional excitatory input for E, F, and G. Assume that all cells are firing at a low basal rate, and that firing rate can both be increased or decreased by an excitatory (+) or inhibitory (-) synapse. What does an excitatory or inhibitory synapse even mean? Think back · where would you expect to find GABA and Glutamate, which would produce an EPSP or an IPSP, and which would increase or decrease the rate of an action potential? Include those three details for both 1 and 2. Excitatory Inhibitory You insert an electrode into a neuron and apply enough current to increase the number of action potentials it fires over time (\'firing rate\'). You then observed changes in firing rates of downstream neurons as an increase or decrease. Answer the following questions with either \'increase\' or \'decrease\' Stimulate Neuron A - what happens to the activity in Neuron 0? Stimulate Neuron B - what happens in Neuron F? Stimulate Neuron A - what happens in Neuron E? Stimulate Neuron C-what happens in Neuron G? Would this neural circuitry work in a reflex arc, if Neuron F synapsed on an extensor and Neuron G synapsed on a flexor?

Solution

1). When the action potential reaches the axon terminal, depolarization of the membrane causes opening of “voltage-gated calcium channels.”

The high concentrations of intracellular calcium causes synaptic vesicles to fuse with the membrane and releases neurotransmitters by a process called exocytosis, which diffuses through the synaptic cleft, and act on the post synaptic neuron’s receptors.

If the released neurotransmitter is excitatory and causes depolarization of post synaptic membrane, then EPSP (excitatory post synaptic potential) is generated, it is known as excitatory synapse. An EPSP triggers the action potential generation and allows the transmission of the impulse to the post synaptic neuron or an organ.

If the released neurotransmitter is inhibitory and causes hyperpolarisation of post synaptic membrane, then IPSP (inhibitory post synaptic potential) is generated, it is known as inhibitory synapse. An IPSP inhibits the action potential generation and does not allow the transmission of the impulse to the post synaptic neuron or an organ.

GABA (gamma-aminobutyric acid) is an inhibitory neurotransmitter and forms inhibitory synapse. Glutamate is an excitatory neurotransmitter, which produces excitatory synapse.