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The Neurological Bases of Human Movement
Chapter 03
Jazmin Ramirez, Megan Wallace & Stephanie Jimenez
Key Points
How are motor control and learning determined at the cellular level
What structures contribute to perception, and how does perception contribute to the learning and control of motor skills
What is kinesthesis and what two visual systems control movements and how do they differ
What are the major structures of the brain contributing to motor learning and control
How does the central nervous system coordinate movements
How are muscular contractions organized and controlled by the central nervous system
Motor Control & Learning at the Cellular Level
At the most fundamental level, the study of motor behavior is the study of connections between the various systems of the body.
This vast system of nerve cells is classified within 2 main divisions: the Central Nervous system and Peripheral Nervous System.
The CNS includes all nerve cells within the brain and spine, whereas all other nerve cells make up the PNS.
Cells originating in the PNS communicate their information to the CNS while those originating in the CNS carry their signals away from the CNS .
Neurons
A neuron is the basic component of the nervous system. The functional classes of neurons found in the nervous system are sensory, motor, & interneurons.
The Basic Anatomy
Cell body – contains the nucleus & other organelles that produce cell energy for the cells activities
Dendrites – receives messages directed toward the cell
Axon – extends from the cells body to carry messages away from the neuron and thousands of terminal branches through to other dendrites
The 3 types of Neurons
Sensory neurons: convey information about the environment from receptors to the CNS.
Motor neurons: form synapses with muscle cells relaying information from the CNS and converting it into movement.
Interneurons: connect and transfer signals between sensory and motor neurons.
How do neurons communicate?
The path of a neural signal traveling toward the CNS (also referred to as the ascending pathway).
Motor neurons follow this pathway to send to messages from the CNS to effectors (ie muscles, glands, etc.)
The path of a neural signal traveling away from the CNS (also referred to as the descending pathway).
Sensory neurons follow this pathway to convey information from both environment & body to the spine and brain.
Afferent
Efferent
The Neural Impulse & Synaptic Transmission
The primary function of a neuron is to transmit a signal, called the neural impulse, to another neuron. This is how the messages get across from one place to another.
https://www.khanacademy.org/test-prep/mcat/organ-systems/neural-synapses/e/neuronal-synapses-questions
https://www.youtube.com/watch?v=tNTQVMhYpD0
Kinesthesis
What is kinesthesis?
A sense of position and movement of the body and limbs and of external forces acting on the body
What does the kinesthetic system involve?
System composed of muscle spindles, Golgi tendon organs, joint receptors and the vestibular apparatus
Kinesthetic sense provides information which we utilize to perform ordinary high skill activities
EX: walking, running, climbing stairs, eating, driving
Perception
The process by which sensations arising from within or outside of the body bright to conscious awareness
Various receptors that allow us to perceive
Proprioceptors
receptors located in the body that supply information about forces within muscles, joint, limb positioning, movement and general body positioning/orientation
Joint Receptor
Mechanoreceptors located in capsules of all synovial joints which provide information on joint angle
perception- how we interpret, give meaning to and orient ourselves in this world
Exteroception
Perception of information in the environment external to the body
Cutaneous Receptors
Receptors located in the dermis and epidermis which stimuli pressure, heat, cold, pain and chemical stimuli
Perception (Cont)
Visual Systems
Focal Visual System
Conscious visual system specialized for object identification
Attention demanding
EX: Texting while walking
Ambient Visual system
Nonconscious visual system specialized for movement control
Activities an individual is not aware of
Ex: Movement
https://www.youtube.com/watch?v=p0RXZPVjJDw&t=414s
00:55 secs.
Ambient visual system is responsible for movement awareness
Focal vs. Ambient Vision
| FOCAL | AMBIENT |
| COLOR VISION | VISION IN SHADES OF GRAY |
| HIGH VISUAL ACUITY | LOW VISUAL ACUITY |
| CENTRAL VISUAL FOCUS | PERIPHERAL VISION |
| NEEDS GOOD ILLUMINATION (DAY VISION) | GOOD IN LOW ILLUMINATION (NIGHT VISION) |
| CONSCIOUS AWARENESS | NON CONSCIOUS PERCEPTION |
| MODERATE DISCERNMENT OF MOVEMENT LIMITED BY CONSCIOUS AWARENESS | HIGH MOVEMENT DISCERNMENT UNDER QUICK AND AUTOMATIC CONTROL |
Optic Flow
The patterning of light rays moving across the retina that supplies information concerning the speed and direction of the movement of objects in the movement
EX: Car ride (things move)
The Human Brain
•The brain mediates all mental functions and all behaviors .
•It weights no more than three pounds and is comprised of 100 billion neurons that integrates sensory input from somatosensory and visual systems that processes in the brain controlling the action of muscular system .
•The brain is composed of the brainstem , cerebellum , and the cerebrum .
The Brain Stem
•It is a pedestal like structure connecting the spinal cord with the upper brain . It controls autonomic functions such as digestion , sweating , and maintenance of attention levels.
• Medulla- part of the brain stem responsible for regulation of blood pressure , respiration , and heart rate.
•Pons- responsible for integrating sensory signals and routing them forward to higher brain centers .
•Reticular formation – area of the brain stem that acts to filter out unrelated sensory input from further processing activities .
•
The Cerebellum
•Role is to make sure that neural messages are routed correctly and to resolve any that are misdirected. It also involved in motor coordination , muscle tone , balance & learning of motor skills .
Cerebrum
•Is composed of the large hemispheres comprising most of the brain .
It functions as the center of the learning , emotional control, memory & voluntary movement . It consisted of a corpus callosum , hippocampus , diencephalon , hypothalamus , thalamus , basal ganglia .
The Limbic System
•It plays a critic role in motivation , formation of memories , emotions & control of movements
Cerebral Cortex
•Cerebral cortex: Outer layer of the cerebrum composed of gray matter, and the major site of higher brain functions such as abstraction, reasoning, decision making, and voluntary motor control.
•Somatosensory cortex : Sensory perception, routes sensory information to motor centers of cortex, and prioritizes sensory sensitivity of bodily regions.
•Motor cortex : Directly controls skeletal muscle contractions, prepares and executes the motor program and prioritizes complexity of motor control available to the bodily regions.
•Homunculus: A bodily representation indicating size of body regions as proportional to area devoted to them by either the somatosensory cortex or motor cortex.
The Neural Control of the Muscular system
•Humans have approximately 600 muscles and 326 skeletal muscles controls all voluntary actions .
•Every muscle fiber in every muscle is controlled by a motor neuron . Neurons that supply skeletal muscle is called an alpha motor .Motor unit is an alpha motor neuron and all the muscle fibers that it supplies .
•Then every muscle in the body is controlled by a number of motor unit, which the exact number varies depending on the size & functional requirement .
•The number of motor units within a muscles motor unit pool is for movement precision and generation of force .
•All – or none law : all the muscle fibers in a motor unit contracts maximally or none contract at all .
•Rate modulation refers to the process of varying the rate or frequency .
•Motor unit recruitment: activated and deactivated in a sequence or order described by the size principle
•They have two different muscle fibers which are slow twitch and fast twitch muscle fibers .
•Within the rate modulation a second contraction is added that produces greater tension than a single twitch called temporal summation . Then , with the additional signals the strength of contractions increases and reaches a point called tetany .
• The modulation of motor unit activation rates , along with recruitment of motor unit based on specific fibers and characteristic makes graduation of muscular forces necessary for many movement skills in which we engage .
