S1: Somatic Sensation Practice Test

Convergence occurs when multiple primary sensory neurons synapse onto a single second-order neuron. That means the second-order neuron receives inputs from several different areas, so its receptive field covers the combined region served by all those primary inputs and becomes one large field. This pooling makes it easier to detect weak or diffuse stimuli because more inputs can reach threshold, but it comes at the cost of spatial precision—the larger the receptive field, the less exact the location of the stimulus. This idea is opposite of a purely isolated system where each primary neuron has its own small field, or a divergent system where one primary neuron would feed multiple secondaries, or a situation where a secondary neuron would have no receptive field.