Final answer:
A greater number of negative signals in a neuron's dendrites or cell body leads to an inhibitory postsynaptic potential, causing hyperpolarization and making an action potential less likely. The correct answer to the question is b) Postsynaptic.
Step-by-step explanation:
The question provided pertains to neural functions, specifically the changes in membrane potential at the synapse in neurons. A negative signal in the neuron's dendrites or cell body, which indicates an increase in inhibitory postsynaptic potentials (IPSPs), will cause the neuron to become hyperpolarized. This hyperpolarization moves the membrane potential away from the threshold and thus decreases the likelihood of an action potential being fired. An inhibitory postsynaptic potential is the correct answer in this context, as it is the graded potential resulting from hyperpolarization due to inhibitory neurotransmitter action such as the influx of Cl- ions when GABA binds to its receptors.
When a neuron receives a combination of EPSPs and IPSPs through various neurotransmitters binding to postsynaptic receptors, the overall effect on the neuron is determined by summation. If the total synaptic input leads to a net depolarization that reaches the threshold potential, an action potential is initiated. Alternatively, if the inhibitory input overshadows, the result is a further hyperpolarization, making an action potential less likely.
The final answer to the question, "A greater number of negative signals in a neuron's dendrites or cell body will cause this kind of potential," is b) Postsynaptic, based on the given clues about the inhibitory action and membrane hyperpolarization described.