Neuromotor Lectures 4(ii)-5 PDF

Neuroscience 6th Edition Dale Purves at al. 2018 Principles of Neural Science 6th Edition 2021. Reviews to be posted into Teaching Folders.  Neuromotor lectures 4(ii)-5 Role of the Brain and Brain Stems Motor Centres in the control of movement...

Neuroscience 6th Edition Dale Purves at al. 2018 Principles of Neural Science 6th Edition 2021. Reviews to be posted into Teaching Folders.  Neuromotor lectures 4(ii)-5 Role of the Brain and Brain Stems Motor Centres in the control of movement * Reflex control of Posture and the role of the brain stem – the reflex modifier. * Voluntary movement roles of motor cortex and cerebellum Alternate flexion and extension can still be activated - when upper motor inputs are damaged Treadmill training improves locomotor function in patients with partial spinal cord injury  Organization of neural structures involved in the control of movement. Purves D. 6th Ed Neuroscience (proprioception – muscle spindles, joint receptors and golgi tendon organs) Lateral and Medial Vestibulospinal tracts Note Muscle spindles are the 1st triggers (sensory) that via a-MNs drive the response This is where Descending inputs from Upper motor centers Brain stem Will provide additional Excitation onto a and g Motor neurons to quicken the reflex response  Two Keys points about postural mechanisms are illustrated in these two examples 1) Feed Forward to anticipate a loss of posture 2) When loss of posture - Feedback mechanisms produce a rapid corrective response (Feedback) Posture – Feedforward mechanisms – many part of the CNS control this aspect of postural control Blind or disturb vestibular apparatus More pronounced postural disturbances Cortex Visual cortex Somatosenory regions (e.g.,. Vestibular cortex) Primary somatosensory cortex Supplementary motor areas (adjacent to primary motor cortex) Cerebellum Spinocerebellum Learning objectives for this part 1) Describe the two key mechanisms of postural adjustment – feedback (reflex) and feedforward (anticipatory). 2) Anticipatory mechanisms (feedforward) is mediated by specialized receptors and brain stem nuclei. 3) Know the Major brain stem nuclei 4) Understand how the Vestibular apparatus can lead to modifying the out puts of motor neurons control extensor muscles of the body 5) Understand how postural reflexes are modified by Anticipatory (feedforward) mechanisms. Cerebellum receives inputs from Cortex, Brain stem and spinal cord (proprioceptor information) # * # Sensory axons from * Sensory axons from Lower SpC connect with Upper SpC connect with Clark’s Nucleus Cuneate Nucleus  Cerebellar Cortex 3 functional subdivisions each subdivision then connects with a particular Deep Cerebellar Nuclei. These nuclei contain the output neurons that project to the motor cortex and or to spinal cord The spinocerebellum has a role in adapting postural response to changing conditions and in scaling the postural response to anticipated postural disturbances e.g. Lateral Vestiubular tract  Learning objective for the Cerebellum 1) Describe the functional divisions of the cerebellum, which are defined by their inputs and outputs 2) Understand how the output activity of the neurons of the Deep Cerebellar Nuclei are controlled by a balance between excitation and inhibition 3) Describe how the cerebellum works as a comparator to refine/correct ongoing movements  Motor Cortex: The Director of Voluntary Movement Basic overview of neuromotor control The motor areas of the cerebral hemisphere Corticospinal tracts (Pyramidal tracts) Associated regions that help control speech (extra) Basal Ganglia (For practical). Motor Cortex Pre-Motor Cortex Corticospinal Neuron (upper motor neuron) Associated Motor Cortical Regions Upper Vs Lower Motor Neuron Lesions X X X The Babinski sign - indicates incomplete upper motor neuron control of local motor neuronal circuitry.  Learning objectives 1) Understand the organization of the motor cortex. 2) Describe the somatotopic organization of the primary motor cortex and how it relates to the fine and crude muscle movement. 3) Understand the location of cortical spinal neurons, and the type of connections they make with motor neurons and interneurons. 4) Know the pre-motor cortical areas 5) Know the major neurotransmitters within the spinal cord and motor cortex (Glutamate [+ve]; Acetylcholine [+ve]; Glycine [-ve]; and GABA [-ve]). 6) Know the fundamental difference between lower and upper motor neuron lesions. Extra – Know the two main language associated areas of the brain and appreciate their location to surrounding motor and auditory regions Extra – For on-line practical the Basal Ganglia – how it works as revealed by Parkinson's Disease