301 exam 2 study guide

Chronic Traumatic Encephalopathy (CTE)

Degenerative brain disease from repetitive TBI; symptoms include dementia, motor control loss, and behavioral decline; diagnosed post-mortem (autopsy).

Neuroplasticity

Changes in neural pathways and synapses / capacity for neurons to structurally and functionally adapt.

Root word "Plasticity"

The ability to adapt.

Cause of Neuroplasticity

Changes in behavior, the environment, and neurological injury.

Long-Term Potentiation (LTP)

Increase in intracellular calcium causes biochemical reactions that increase the excitability of the synapse; plays a role in memory storage (hippocampus) and motor learning (cerebellum).

Long-Term Depression (LTD)

Decrease in calcium causes a different set of reactions that decrease the excitability of the synapse; plays a role in memory storage (hippocampus) and motor learning (cerebellum).

Neurogenesis vs. Synaptogenesis

Neurogenesis is new neurons (in hippocampal and olfactory cells, doesn't contribute much); Synaptogenesis is new synapses (occurs in adults too, due to axonal sprouting).

Axonal Sprouting

Growth of new nerve endings that connect to undamaged cells to form new neural pathways.

Diffusion Tensor Imaging (DTI)

Neuroimaging like an MRI that looks at water diffusion in white matter tracts of the brain.

Functional MRI (fMRI)

Neuroimaging that measures deoxyhemoglobin distribution (formation of hemoglobin without oxygen = predominant protein in red blood cells) to track brain activity.

Transcranial Magnetic Stimulation (TMS)

Excites neurons in the brain by generating an electrical current from a changing magnetic field, producing Motor Evoked Potentials (MEP).

Motor Evoked Potentials (MEP)

Stimulating motor pathways in the brain and receiving an electrical signal from either the spinal cord, peripheral nerves, or muscles.

Conditions Treated by TMS (Research)

Migraines, depression, mental illness, and autism (in early stages of research).

Why Utilize Tele-Rehab?

Traditional therapy is too costly and not covered by insurance; too hard to get to a clinic for some patients; research suggests more therapy yields improvements in virtually all patients.

JAVA Therapy

Web-based home therapy for arm/hand injuries where patients use an input device tracking motion/providing assistance, logging into a website to complete exercises and receive quantitative performance feedback.

TheraJoy

Home therapy system where patients use a joystick to increase range of motion in upper extremities, tracking hand position, force data, different planes of motion, etc.

Epidural Stimulation Setup

Electrode array surgically placed over a specific spinal cord segment.

How Epidural Stimulation Works

Activates natural pathways carrying signals out of muscles (unlike FES which directly stimulates muscle); raises the level of excitability of spinal circuits.

Epidural Stimulation Success Rate

Restores function after spinal cord injury with a 50-80% success rate.

Autonomic Nervous System (ANS)

Involuntary, reflexive nervous system controlling organs (heart, stomach, intestines, bladder), eye function, digestion, and smooth muscle (HR and BP).

Sympathetic Nervous System

Mediates "Fight or Flight" (facing perceived danger vs. running from danger) and "Freeze" (becoming immobile).

Parasympathetic Nervous System

"Rest and Digest" system that slows down body's metabolic processes and conserves energy when relaxed.

Enteric Nervous System

Directly controls the GI system; known as "The second brain in your gut".

Somatic Nervous System

Voluntary control of movement via sensory (afferent) and motor (efferent) pathways.

Sensory Systems Function

Sensory receptors change physical energy into electrochemical energy.

The Six Senses

1. Mechanoreceptors, 2. Proprioception, 3. Olfaction, 4. Ocular, 5. Auditory, 6. Gustation.

Four Classes of Sensory Receptors

1. Mechanoreceptors (touch, balance, hearing, pain), 2. Chemoreceptors (pain, taste, smell), 3. Photoreceptor (sight), 4. Thermoreceptor (temperature, pain).

Four Components of Sensation

Modality (vision, hearing, touch, taste, smell, proprioception), Duration (adaptation if stimulus persists), Specificity (chemospecificity, tone, location, two-point discrimination), Intensity (coded by frequency of firing).

Nociceptors

Pain sensors.

Noxious Stimuli

Stimuli that "threatens" the body or its integrity.

Proprioception Definition

Body's subconscious ability to sense its own position, orientation, movement, and balance in space without relying on vision ("sixth sense").

Three Pieces of Proprioceptive Info

1. Limb position sense (stationary), 2. Sense of limb movement (kinesthesia), 3. Muscle force.

Muscle Spindles (Structure, Function, Location)

Specialized muscle fibers (intrafusal, ~1 cm long) running in parallel with muscle fibers; innervated by gamma motor neurons; sense muscle length and velocity.

Golgi Tendon Organs (Structure, Function, Location)

Located in series at the junction of muscle and tendon; sense muscle tension (more active during concentric contractions compared to muscle spindles).

Joint Receptors

Mechanoreceptors located in joint capsules that help provide feedback on joint position and movement.

Two Types of Photoreceptors

1. Rods (night vision / low light / low stimuli), 2. Cones (day vision / color / more resolution).

Sensation vs. Perception

Sensation transforms physical stimuli to internal representations; Perception makes meaning of sensation by integrating memory with sensation.

Cycle of the 4 Parameters for Perception

1. Detection (is there a stimulus?), 2. Discrimination (one or two stimuli? same or different?), 3. Recognition (associating stimulus with memory), 4. Scaling (comparing similar but different stimuli on a ratio scale).

Reflexive Movement

Involuntary/unconscious response to stimuli; serves as building blocks for complex movements and is used for non-invasive clinical diagnosis.

Short Loop Reflex

Completely peripheral; local sensory-motor integration without central processing (e.g., Gastrocolic Reflex: stomach filling triggers GI motility).

Long Loop Reflex

Involves afferent pathways entering the spinal cord/brain to send efferent signals back out for ~50-100 ms limb position adjustments.

Monosynaptic Reflex

Only 2 neurons with 1 synapse (motor + sensory); cannot be eliminated/overridden; e.g., stretch reflex.

Polysynaptic Reflex

More than 2 neurons involved with an interneuron present to help control coordinated patterns; can be controlled or overridden; response to noxious stimuli.

Voluntary Movement Characteristics

Prepares muscles for upcoming movements (preparation and imaging), receives information from sensory cortex (planning and organizing); premotor cortex fires before primary motor cortex.

Hierarchy of Voluntary Movement Control

1. Cerebral Cortex (highest level), 2. Cerebrum, Basal Ganglia, Thalamus, 3. Spinal Cord, 4. Alpha Motor Neurons.

Direction & Force of Voluntary Movement

Direction is determined by which neurons in the cerebral cortex are active; Force is determined by the firing frequency of those neurons.

Rhythmic Movements

Combination of reflexive and voluntary (walking, chewing, scratching, etc.); voluntary to initiate and reflexive as they carry out.

Primary Motor vs. Premotor Cortex

Premotor cortex fires before primary motor cortex and its role is in planning and execution.

Apraxia

Condition with no sensory loss or weakness, but an inability to perform complex actions.

Motor Unit (Structure, Function, Location)

An alpha motor neuron and the muscle fibers it innervates; fibers may be scattered throughout the muscle; operates on the all-or-none principle.

Henneman's Size Principle

Motor units are recruited from smallest to largest based on intensity; smallest slow-twitch units are recruited first, followed by larger fast-twitch units.

Rotational Activation of Motor Units

The nervous system rotates active motor units and muscle fibers to maintain constant force and limit fatigue.

Muscle Twitch

Force produced by an isometric muscle (length not changing) in response to an action potential in one or more motor units.

Wave Summation & Tetanus

Summation of twitches leads to tetanus where muscles are not allowed to relax between action potentials; human muscles reach tetanus at 50-60 Hz frequency of wave cycles.

Increasing Force Production

Nervous system increases force by recruiting more motor units and increasing action potential frequency (Rate Coding).

Control Theory in Reaching

Reaching tasks involve smooth, straight hand trajectories and bell-shaped velocity profiles managed via feedforward and feedback control.

Force Field Experiments (Shadmehr & Mussa-Ivaldi 1994)

Subjects made planar reaches using a Phantom haptic robotic arm applying a force field perpendicular to the plane of motion, proving the brain forms internal models.

Motor Adaptation to Force Fields

The brain adapts by forming predictive internal models rather than relying solely on high-cost mechanical co-contraction.

Feedforward vs. Feedback Control

Feedforward (open-loop) predicts motor commands before movement using internal models; Feedback (closed-loop) uses real-time sensory corrections during movement.

Negative vs. Positive Feedback

Negative feedback opposes deviation from a set point (e.g., body temperature regulation); Positive feedback amplifies deviation or processes (e.g., uterine contractions, blood clotting).

Impedance Control

A high muscle co-contraction strategy used as a last resort in control; very energy inefficient.

Decision Making Steps (Stoplight Example)

1. Stimulus identification (seeing a yellow light), 2. Response selection (deciding whether to stop or go), 3. Response programming (executing the physical foot movement).

Reaction Time (RT) + Movement Time (MT)

RT is time from stimulus to movement onset; MT is time from movement start to completion; RT + MT = Total Response Time.

Observing Nervous System Processes

Observed by designing experiments dependent on different phases of information processing.

Two Components of Reaction Time

Premotor time (central processing before muscle activation) and Motor time (electromechanical delay at the muscle).

Information Processing Model Stages

1. Stimulus Identification, 2. Response Selection, 3. Response Programming.

Improving Stimulus Identification (Unanswered Notes Answered)

Clarity of signal, intensity/brightness/loudness, and reducing signal ambiguity or prior familiarity can help improve and speed up stimulus identification.

Influencing Response Selection to alter RT (Unanswered Notes Answered)

Increasing or decreasing the number of choices (Hick's Law), altering stimulus-response compatibility, or introducing conflicting cues like the Stroop effect.

Hick's Law

Reaction time increases logarithmically as the number of stimulus-response choices increases.

Stimulus-Response (S-R) Compatibility

The degree of natural correspondence between a stimulus and its required response (e.g., poor compatibility like confusing elevator buttons or push/pull doors increases RT and errors).

Stroop Effect

Demonstrates how conflicting semantic and visual information (e.g., color word written in a different ink color) delays response selection and increases reaction time.

Response Reprogramming

The time required to alter or substitute a planned motor program when a sudden change in instructions occurs.

Factors Influencing Response Programming (Unanswered Notes Answered)

Precuing (providing advanced warning), foreperiod duration (time between warning and go signal), and repetition of movement (practice or familiarity).