Neuromuscular Control & Information Processing (Quiz 3)

Information Processing (CNS Analogy)

The CNS acts like a computer, processing sensory input from the periphery to generate motor output.

Reaction Time (RT)

The temporal delay between the presentation of a stimulus and the initiation of a response.

Three Stages of Information Processing

Stimulus Identification, Response Selection, and Response Programming (neuromuscular system primed)

Stimulus Identification Stage

Recognizing a stimulus through stimulus detection and pattern recognition.

Response Selection Stage

Deciding which movement (or lack thereof) to make based on sensory information.

Factors Influencing Response Selection Time

The number of stimulus-response alternatives and stimulus-response compatibility.

Response Programming Stage

Organizing and priming the neuromuscular system to execute a specific motor task.

Donders' Subtractive Method

A framework demonstrating that reaction time increases as task complexity and processing stages increase.

Simple Reaction Time Task

A task involving one known stimulus and one single predefined movement response.

Go/No-Go Reaction Time Task

A task requiring a response to one specific stimulus while withholding action for another.

Choice Reaction Time Task

A task with multiple stimuli where each stimulus requires a distinct response.

Henry & Rogers (1960) Experiment

Demonstrated that increased movement complexity increases reaction time during the response-programming stage.

Short-Term Sensory Store (STSS)

A memory component holding massive amounts of raw sensory information for very brief periods. (Somatosensory, auditory, visual stimuli, etc.)

Short-Term Memory (Working Memory)

A limited-capacity buffer integrating incoming sensory data from STSS with long-term memory.

Sensory information in short-term memory integrated with information from long-term memory (e.g. stored motor programs) during response selection stage

Long-Term Memory

Vast storage area containing sensory memories and motor programs transferred via practice.

Closed-Loop (Feedback) Control System

A movement control system that processes real-time sensory feedback to continually adjust motor output. CNS changes output based on sensory input

Open-Loop Control System

A feedforward system executing pre-planned motor commands independently of sensory feedback during movement.

•Must have knowledge of status of system and surroundings

•Feedback available but not utilized during activation

Essential for selection of appropriate activity

Proprioception

The perception of joint position sense and spatial orientation of body segments.

Kinesthesia

The conscious sensation of joint motion and movement.

Force Sense

The sensation of the level of force produced by muscle activation.

Muscle Spindle Function

Tenomuscular receptor sensitive to muscle length and rate of change in length.

Golgi Tendon Organ (GTO) Function

Tenomuscular (Ib) receptor sensitive to muscle tension produced during contraction.

Articular Receptors

Joint receptors sensing displacement, acceleration, and load.

Cutaneous Receptors

Skin receptors sensing touch, pressure, pain, and temperature, critical for precision grip control.

Ensemble Coding

CNS integration of redundant sensory inputs into a single stream to resolve sensory ambiguity. Uses redundancy of information

Reflexive Neuromuscular Response Latencies

M1 (20-50ms), M2 (70-100ms), M3 (120-130ms), and Voluntary response (>250ms).

Dynamic Restraint System

Muscular system enhancing stability via joint compression, eccentric (resistance to joint lengthening) energy absorption, and reflexes.

Ankle Inversion Protection Finding (Konradsen et al.)

Reflexive response time (~176ms) is too slow to prevent ligament injury (~107ms), requiring feedforward control.

Mechanical Stability

Passive arthrokinematic ROM governed by static capsuloligamentous constraints. Assessed via manual joint stability tests.

Functional Stability

Dynamic joint stability derived from the dynamic restraint system and sensorimotor control. Revealed clinically via word-of-mouth

Functional Instability Cause

Joint 'giving way' caused by deafferentation and diminished neuromuscular control, independent of mechanical laxity.

Why is CNS A Black Box Phenomenon?

Nature of internal processes inferred

What is Donder's Substractive Method

Evidence of info processing, reaction time increased with tasks of increasing complexity

Stimulus Identification 2 Substages

1. Stimulus Detection: Sensory organs must detect and transmit information. Input must be interpreted

2. Pattern Recognition: Most movement tasks associated with multiple stimuli. Inter-related stimuli typically presented in a prescribed pattern

What Stage Was Removed in The Henry & Rogers Experiment?

For all conditions, the stimulus was the same, and subjects were informed of the appropriate response (i.e. no response selection stage)

How are sensory and motor programs transferred to long term memory?

Via rehersal or practice

How Does Short Term Memory Function

Integrates incoming STSS with Long-Term sensory memories to create short-term memory.

What are three forms of sensory information necessary for initiation and regulation of movement.

-State of the environment

-State of the body (neural and mechanical)

-State of body with respect to the environment

Multiple Sources of Info Available to Inform CNS

-Vision

-Tenomuscular receptors

-Articular receptors

-Cutaneous receptors

What Sense is Most Important For Info of External Environment

Vision provides the most important sensory information regarding external environment.

•Accuracy greatly impaired without

•Postural control deficits

-Role in planning and executing movement

•Target identification

•Obstacle identification

-Essential for error correction

Diagram Ensemble Coding

How are proprioception, kinesthesia, and force sense used to inform neuromuscular control?

-Online (real-time) monitoring of long-duration movements

-Preparatory information and goal-oriented feedback for rapid movements

Long duration movements Goal And Error Analysis

-Error analysis and correction require considerable time

•Goal is to maintain a constant state/path

-Driving a car

Describe Error in Short duration Movements (5 Step Process of Error Correction)

CNS requires considerable time to recognize and process sensory information, and to generate a subsequent neuromuscular response (correction)

5 Step Process

•Error generation

•Error detection

•Correction identification

•Correction initiation

•Error correction

If movement is too fast, this process cannot occur and it is controlled exclusively by feedforward mechanisms.

What is the primary difference between long and short-duration error correction

•Long-duration activities assume conscious awareness for error detection and correction

•Reflexes afford subconscious error detection and correction during long- and short-duration activities

What is a joint perturbation?

-Joint maintained at a given position

•Change in position = error

-Load on joint increased suddenly

-Muscle response and kinematics recorded simultaneously

Medium and Long Latency Reflexes

-Ia afferent synapses with:

•Homonymous a-mn

•Higher integrative centers

-Higher-level sensory integration leads to "more appropriate" response

•Greater latency due to greater processing time

What is the H-Reflex?

-electrical analog to spinal stretch reflex

•Amplitude attenuated via changes in postural status and phase of gait

Reflexive neuromuscular control process

Joint perturbations excite tenomuscular and articular receptors --> Elicits reflexive muscle activity to resist perturbation --> Ligament stress induced reflex

What happens to reflexes under fatigue?

They increase reaction time

Golgi-like endings produce

-Produces ligament stress-elicited reflex

Muscle Spindles cause which reflexes?

-Spinal stretch reflex

-Medium-latency stretch reflex

-Long-latency stretch reflex

What is the Dynamic Restraint System?

Reflexes derived from articular and tenomuscular receptors resist joint perturbation

Feedforward neuromuscular control

-Voluntary activity derived from the integration of sensory information and previous experience

-Preparatory/anticipatory muscle activity

Draw the Functinal Stability Paradigm

What are the limitations of the GTO?

- Indirect indication of joint position sense and kinesthesia

-Limited usefulness due to potential for multiple levels of sensory input at same joint position

What are the limitations of articular receptors?

•Indirect indication of joint position and kinesthesia

•Different afferent activity at same joint angle for differing levels of contraction

• Primarily active in extreme ROM