Neural Systems and Motor Control: Cerebellum, Basal Ganglia, and Reflexes

Cerebellum

Timing/coordination neural system affected in hand movement coordination.

Basal ganglia

Neural system involved in initiation/modulation of movements.

Proprioceptors

Sensory feedback sources that may be impaired, disrupting motor planning.

EMG

Electromyography measures muscle activity during balance or reaching tasks.

Central pattern generators (CPGs)

Spinal circuits that produce rhythmic movements independently of the cortex.

Resting membrane potential

Approximately -70 mV, allows neurons to respond quickly.

Action potentials

Signals that propagate from sensory input to motor output, enabling reflexes and voluntary movement.

EPSPs

Excitatory postsynaptic potentials that influence whether a neuron fires.

IPSPs

Inhibitory postsynaptic potentials that influence sensory processing and motor output.

Saltatory conduction

Myelination allows action potentials to jump between nodes, increasing signal speed.

Demyelination

Condition (e.g., MS) that slows reflexes and voluntary movements.

Lateral inhibition

Mechanism that enhances contrast/edges in visual processing.

Rods

Photoreceptors that detect dim light, aiding navigation.

Cones

Photoreceptors that detect color/detail, aiding object recognition.

Visual pathway

Pathway from retina to LGN to visual cortex, integral for visually guided movement.

Constructive perception

Perception shaped by memory and attention, affecting decision-making and motor responses.

Voluntary movement planning

Process involving premotor and supplementary motor areas for planning and primary motor cortex for execution.

Pyramidal tract

Neural pathway responsible for voluntary fine movements.

Extrapyramidal tract

Neural pathway responsible for involuntary posture and coordination.

Mirror Neurons

Neural recordings show firing during both action execution and observation, explaining imitation, skill acquisition, and understanding others' intentions.

SCN and Melatonin

Light input to SCN regulates melatonin release from pineal gland; controls sleep timing, affecting attention, motor performance, and cognition.

Ultradian Rhythms

~90-min NREM/REM cycles optimize restorative processes, memory consolidation, and motor skill improvement.

Sleep Deprivation

Reduced REM and NREM impair memory, learning, emotional regulation, and motor performance in experiments measuring cognitive or motor tasks.

Basal Ganglia Lesions

Tasks requiring initiation or sequencing of movement reveal delayed or impaired responses, connecting neural circuits to observed motor behavior.

Multiple Sclerosis

Measuring conduction speed in demyelinated axons shows slowed action potentials → slower reflexes and motor deficits.

REM Sleep Behavior Disorder

EMG during REM shows absence of normal muscle atonia, linking inhibitory circuits to abnormal motor output during sleep.

NREM Slow-Wave Sleep

Comparing pre- and post-sleep performance shows consolidation occurs during deep sleep, linking restorative processes to behavior.

Sensory Feedback

Experiments altering proprioceptive or visual input show reduced movement accuracy, demonstrating feedback's role in movement correction.

Action Potentials in Reflexes

Recording sensory and motor neuron activity during reflexes demonstrates how depolarization and repolarization sequences produce rapid, coordinated responses.

Circadian Rhythms and Cognition

Testing cognitive tasks under controlled light/dark cycles shows SCN and melatonin influence alertness, attention, and learning.

Excitatory and Inhibitory Synapses

Intracellular recordings show EPSPs and IPSPs integration determines if neurons fire, translating sensory input into motor and cognitive outputs.

Motor Adaptation

Altering visual or proprioceptive feedback during tasks shows motor cortex and cerebellum adjust motor commands to maintain accuracy.

REM

What is NREM sleep?

Non-Rapid Eye Movement sleep (stages 1-4) with slower brain waves.

What are the main functions of NREM sleep?

Energy restoration, cellular repair, immune support, and motor skill consolidation.

What happens during Stage 1 of NREM?

Light sleep; muscles relax and it's easy to wake.

What happens during Stage 2 of NREM?

Deeper sleep with sleep spindles; begins memory consolidation.

What happens during Stage 3/4 of NREM?

Deep sleep with delta waves; major physical restoration and motor skill consolidation.

What is REM sleep?

Rapid Eye Movement sleep with fast, wake-like brain activity and muscle paralysis.

What are the main functions of REM sleep?

Memory consolidation, learning, emotional regulation, and brain plasticity.

How does NREM sleep affect behavior?

Supports physical recovery and motor skill learning, improving coordination and performance.

How does REM sleep affect behavior?

Enhances memory, learning, and emotional regulation, helping cognitive performance and problem-solving.

Why are both NREM and REM sleep important?

Both are needed for full recovery: NREM restores the body, REM restores the brain.