This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sensory System, Subject name: Physiology
The ability to detect two points simultaneously applied to the skin is based on which physiologic mechanism? 
Select and explain. 
A. Presynaptic inhibition, B. Feed-back inhibition, C. Feed-forward inhibition, D. Lateral inhibition
D: Lateral inhibition
Answer: D: Lateral inhibition 
Explanation: Lateral inhibition is the basis of ability to detect two points simultaneously applied to the skin. Every sensory pathway, when excited, gives rise simultaneously to lateral inhibitory signals; these inhibitory signals spread to the sides of the excitatory signal and inhibit adjacent neurons. Presynaptic inhibition: decrease release of excitatory neurotransmitter. Endogenous analgesia system Feed-forward inhibition: when excitatory neurons exciteinhibitorycells, which theninhibit a group of postsynaptic excitatory neurons. Seen in cerebellum (Cerebellar learning) Recurrent/Renshaw cell inhibition: Sho inhibitory interneuron Collaterals excites renshaw cell which in turn inhibits the same neuron Purpose: delays muscle fatigue, sharpens the signal to muscle