Exam 2

"question": "What are central pattern generators (CPGs)?",

"answer": "Neural circuits that produce rhythmic outputs like walking or breathing without rhythmic sensory or descending inputs."

"question": "Where are CPGs located, and how do they contribute to motor control?",

"answer": "Found in the spinal cord and brainstem; they generate autonomous motor patterns and can function without sensory feedback."

"question": "What is fictive locomotion?",

"answer": "Motor patterns recorded without actual movement, showing that rhythmic motor patterns are centrally generated."

"question": "What is the half-center model of locomotion?",

"answer": "Two groups of neurons inhibit each other to produce alternating rhythmic activity."

"question": "How can sensory feedback influence CPGs?",

"answer": "It can reset/modulate rhythm, prolong movement phases, and aid phase transitions."

"question": "What is the function of the neuromuscular junction (NMJ)?",

"answer": "Synapse between motor neuron and muscle fiber where ACh causes contraction."

"question": "What happens at the NMJ during muscle contraction?",

"answer": "AP → Ca²⁺ influx → ACh release → Na⁺ influx in muscle → depolarization → contraction."

"question": "What is myasthenia gravis and how does it affect the NMJ?",

"answer": "Autoimmune attack on ACh receptors → impaired transmission → muscle weakness."

"question": "What is the difference between upper and lower motor neurons?",

"answer": "Upper motor neurons originate in brain/cortex; lower motor neurons directly innervate muscles."

"question": "What is the size principle in motor unit recruitment?",

"answer": "Smaller units are recruited first due to higher excitability; larger units follow as force demand increases."

"question": "How does reciprocal inhibition work in motor control?",

"answer": "Contracting muscle inhibits its antagonist via interneurons to allow smooth movement."

"question": "What role do gamma motor neurons play in muscle contraction?",

"answer": "Adjust muscle spindle sensitivity by contracting intrafusal fibers during movement."

"question": "What is the stretch reflex and what components are involved?",

"answer": "Muscle stretch activates spindle afferents → excites alpha motor neurons → contraction."

"question": "What are Renshaw cells and how do they function?",

"answer": "Inhibitory interneurons providing negative feedback to alpha motor neurons."

"question": "What is a motor unit and how is it organized?",

"answer": "A single alpha motor neuron and all muscle fibers it innervates."

"question": "How do fast and slow muscle fibers differ?",

"answer": "Fast: quick, fatigues fast. Slow: slower, resistant to fatigue, used for endurance."

"question": "What is the Golgi tendon organ (GTO) reflex?",

"answer": "Detects tension and inhibits same muscle's motor neurons to prevent damage."

"question": "What is the difference between muscle spindle and GTO function?",

"answer": "Spindle: stretch detection/length. GTO: tension detection/force."

"question": "What is the function of the supplementary motor area (SMA)?",

"answer": "Plans and initiates internally generated movement and sequences."

"question": "What is the function of the premotor cortex?",

"answer": "Plans/selects movements in response to external cues."

"question": "How does the cerebellum contribute to motor control?",

"answer": "Compares intended vs actual movement, adjusts for coordination and precision."

"question": "What happens when the cerebellum is damaged?",

"answer": "Ataxia, intention tremor, dysmetria, and poor coordination."

"question": "What is the basal ganglia’s role in motor control?",

"answer": "Initiates desired movement and inhibits unwanted ones through direct/indirect pathways."

question": "What is the difference between the direct and indirect pathways in the basal ganglia?",

"answer": "Direct: facilitates movement (disinhibits thalamus); Indirect: inhibits movement (more inhibition of thalamus)."

"question": "What is Parkinson’s disease and how does it affect motor control?",

"answer": "Degeneration of substantia nigra dopamine neurons → decreased direct pathway activity → motor symptoms like bradykinesia, tremors."