Neuromotor Basis for Motor Control Lecture PDF

Review from last class Which motor control theory does this video make you think of? Why? Dynamical systems theory – the walker self-organizes into a walking pattern without any central control 1 Motor Control Theories Dynamical Systems Theory: Stabi...

Review from last class Which motor control theory does this video make you think of? Why? Dynamical systems theory – the walker self-organizes into a walking pattern without any central control 1 Motor Control Theories Dynamical Systems Theory: Stability – a behavioural steady state of a system (e.g., anti-phase or in- phase finger movements) Attractors – stable behavioural states (e.g., at 3 mi/hr people adopt a walking coordination gait, at 10 mi/hr people adopt a running coordination gait), attractor states in human movement tend to be energy efficient Phase transition – point at which instability characterizes the system Self-organization – given a certain set of conditions, stable patterns of behaviour emerge (e.g., crowd behaviour, school of fish, flock of birds, group of muscles) Order parameters – functionally specific variables that define the overall behaviour of a system Control parameters – the variable that when increased or decreased influences the stability of the system 2  KIN 280 – Motor control and Learning Neuromotor Basis for Motor Control Faculty of Kinesiology and Health Studies University of Regina, Regina, SK January 24, 2025 3 Neuromotor Basis for Motor Control Why is understanding how the nervous system controls movement important? It is particularly important when it is not working 4 Neuromotor Basis for Motor Control Learning Outcomes: Identify the structural components of the CNS that are most directly involved in control of movement and describe their primary functions Identify and describe the neural pathways that make up the descending tract Describe a motor unit and how they are controlled to vary muscle contraction force 5  Neuromotor Basis for Motor Control Brain: Cerebrum made of the right and left hemispheres Cerebral cortex is the outer layer and divided into four lobes: Frontal lobe – plans, controls, coordinates, executes Parietal lobe – interacts with motor cortex, PMC, SMA, integration of movement preparation and execution info Temporal lobe – memory, language Occipital lobe – important centre for processing visual input 6 Neuromotor Basis for Motor Control Click on the frontal lobe. 7 Neuromotor Basis for Motor Control Click on the parietal lobe. 8 Neuromotor Basis for Motor Control Click on the temporal lobe. 9 Neuromotor Basis for Motor Control Click on the cerebellum. 10 Neuromotor Basis for Motor Control Brain: Frontal lobe: Prefrontal cortex – attention, decision- making, planning Supplementary area – planning and movement preparation Premotor area – planning and movement preparation Primary motor cortex – sends motor commands Parietal lobe: Somatosensory cortex – sensory processing Posterior parietal cortex – integration of multiple sources of sensory info (visual, proprioception, etc.) 11 Neuromotor Basis for Motor Control Prefrontal cortex integration of multiple sources of sensory info (visual, Supplementary area proprioception, etc.) sends motor commands Premotor area attention, decision-making, Primary motor cortex planning Somatosensory cortex sensory processing Posterior parietal cortex planning and movement preparation 12  Neuromotor Basis for Motor Control Brain: Cerebellum Very complex part of the brain – 100 billion neurons compared to 25 billion in cortex Multiple nuclei – grey matter relay centres Receives sensory input from proprioceptive, vestibular systems Communicates with primary motor cortex Involved in error correction, Nicholls text, 2001 balance, coordination Cerebellar Cerebellar Thalamus Sensorimotor Cortex nuclei Cortex 13  Motor Control Theories Internal model: Task Motor Motor output selection command Comparison between efference copy (desired output) and Inverse Efference Effect on sensory info model copy world (actual output) thought to occur in the cerebellum! Sensory Sensory input processing 14  Neuromotor Basis for Motor Control Brain: Basal Ganglia Multiple nuclei – grey matter relay centres Communicates with prefrontal cortex and supplementary motor area Involved in planning, movement initiation Prefrontal cortex Basal ganglia Thalamus Cortex Nicholls text, 2001 Supplementa ry motor area 15 Neuromotor Basis for Motor Control Brain: Cerebrum Thalamus Hypothalamus Midbrain Pons Cerebellum Medulla oblongata Spinal cord 16 Neuromotor Basis for Motor Control 17  Neuromotor Basis for Motor Control Think about the movement challenges you saw. What parts of the brain might not be working? Rank Responses 1 1 18 Neuromotor Basis for Motor Control Freezing of gait in a new environment Movement planning, preparation, initiation  Prefrontal cortex, premotor areas, basal ganglia The visual and auditory cues are like an aide for the dysfunctional brain regions 19 Neuromotor Basis for Motor Control Spinal cord: Gray matter (gray area, cell bodies, dendrites, axon terminals) White matter (white area, axons) Ventral horn and ventral column (1 and 4, motor) Dorsal horn and dorsal column (2 and 6, sensory) Sensory pathway (12), Motor pathway (11) Many different tracts running up the white matter: Ascending: Spinothalamic, spinocerebellar Descending: corticospinal, rubrospinal, reticulospinal. Vestibulospinal, tectospinal 20 Neuromotor Basis for Motor Control Brain and spinal cord (descending): Motor signals originate in the cerebrum Travel through the internal capsule Travel down through the midbrain and pons Crosses over at the medulla Through the ventral column to the ventral horn 21 Neuromotor Basis for Motor Control Neuromuscular: Motor neurons: Alpha motor neuron – innervate skeletal muscle fibres, The “Final Common Pathway” – Charles Sherrington Gamma motor neuron – innervate muscle spindles (stretch receptors) Motor unit (MU) Alpha motor neuron and all of the muscle fibres it innervates Each muscle has many motor units In large muscles (e.g., gastroc), single motor neuron innervates LOTS of muscle fibres (1:1600) In small muscles (e.g., extraocular), single motor neuron innervates a FEW muscle fibres (1:10) Neuromuscular junction Contact between a motor neuron and a muscle fibre www.muaythaischolar.co m 22  Neuromotor Basis for Motor Control Neuromuscular: Vary contraction force by: MU recruitment - Increasing number of motor units activated, to increase number of muscle fibres active, to increase force exerted by the muscle Henneman’s Size Principle: Small MUs recruited first (low threshold), large MUs last (high threshold) Small MUs innervate slow twitch muscle fibres with low innervation ratios; Large MUs tend to innervate fast twitch muscle fibres with high innervation ratios 23  Neuromotor Basis for Motor Control Neuromuscular: Vary contraction force by: Rate coding- changing the firing rate of different motor units (range 5-60 Hz, action potentials/s) A single action potential produces a contraction known as a twitch A train of impulses produces a summation of twitches Fused and unfused tetanus 24  Neuromotor Basis for Motor Control Myasthenia gravis (MG) is a neuromuscular disease that destroys receptors (ACh) at the neuromuscular junction. What sort of symptoms might you expect to see in someone with MG? Rank Responses 1 2 3 4 5 6 25 Neuromotor Basis for Motor Control Would you expect small or large muscles to be affected first? Rank Responses 1 2 3 4 5 6 26 Neuromotor Basis for Motor Control Summary of Learning Outcomes: Identify and describe the structural components of the CNS that are most directly involved in control of movement and describe their primary functions Spinal cord (ventral and dorsal horns and columns), brain (lobes, cortical areas, cerebellum, basal ganglia) Identify and describe the neural pathways that make up the descending tract Motor cortex, internal capsule, mid-brain and pons, cross over at medulla, ventral column, ventral horn, alpha motor neuron Describe a motor unit and how they are controlled to vary muscle contraction force Alpha motor neuron and all of the muscle fibres it innervates; recruitment, rate- coding 27 Neuromotor Basis for Motor Control Monday Jan 27– Sensory components of motor control (Part 1) 28