Lab #2: Recording Human Nerve Reflexes (iWorx)
1. What is the formula used to calculate the Conduction Velocity in these experiments?
• Conduction Velocity (m/sec) = Total path length (mm) / (Mean reflex time (msec) –
• Subtract 0.5msec to account for the synaptic transmission time of the neuromuscular
2. Does the subject’s reflex time change with different stimulus strengths? Why does it or doesn’t it
• Reflex time doesn’t change with different stimulus strength because the rate at which an
action potential moves through a neuron only depends on its diameter and whether or not
• Since the action potential has the same path length whether it is a light, medium, or
strong stimulus, the reflex time will always be the same
3. Which muscle groups are involved in plantar flexion and in dorsiflexion of the ankle?
• Plantar flexion (movement which increases approximate 90 degree angle b/w front part of
foot and shin) ▯gastrocnemius and soleus
• Dorsiflexion: movement which decreases angle b/w dorsum of the foot and the leg
bringing toes closer to the shin ▯tibialis anterior
4. How does temporal summation in a neuron differ from spatial summation?
• Temporal summation occurs when two graded potentials from one presynaptic neuron
occur close together in time and summate (create graded potential larger than either one
alone) to create an action potential
• Spatial summation occ