Numerous nerve impulses arriving at a synapse at the same time exert a cumulative effect?

Answer 1

Kind of. Each neurone can have thousands of inputs from other neurones arriving at the same time. It all depends on the types of signal arriving from the other neurones.

There are 2 types of incoming signal;

1. Excitatory Post-synaptic potentials (EPSPs) - These inputs depolarise the neurone (bring the negative voltage of the neurone closer to 0mV).

2.Inhibitory Post-synaptic potentials (IPSPs) - These inputs hyperpolarise the cell (make the neurone voltage more negative).

Some of the inputs coming to the neurone will be EPSPs, some IPSPs. If all the inputs come in and there are more EPSPs then the neurone will depolarise. If the neurone depolarises to the firing threshold (around -40mV) then an action potential will be propagated and the neurone will transmit the message to the next neurone in the chain.

If the majority of the inputs are IPSPs then the neurone will hyperpolarise and will not fire.

If there are more EPSPs than IPSPs but the neurone still doesn't depolarise enough to reach the firing threshold then the neurone will not fire.

Answer 2

When multiple nerve impulses arrive at a synapse simultaneously, they can cause the release of a larger amount of neurotransmitter, leading to a stronger excitatory or inhibitory effect on the postsynaptic neuron. This phenomenon is known as temporal summation and plays a key role in neural signaling and information processing in the nervous system.