PHYL 4518 Motor Learning - Mount Royal University PDF

PHYL 4518 Motor Learning F2024 – Wk 6 Zoe Chan, PhD [email protected] Unit 4 Central Neural Mechanisms in Planning and Initiating Movement PHYL 4518 Motor learning F2024 – Wk 6  Describe the motor control functions of each of the major components o...

PHYL 4518 Motor Learning F2024 – Wk 6 Zoe Chan, PhD [email protected] Unit 4 Central Neural Mechanisms in Planning and Initiating Movement PHYL 4518 Motor learning F2024 – Wk 6  Describe the motor control functions of each of the major components of the CNS, and the integration of these functions in producing effective motor planning Explain how physical training and practice can impact the CNS Today’s Identify the impacts of central fatigue learning on force production objectives  CNS and motor control Gather data The CNS is responsible for planning and initiating motor actions Goals/ Memories motivation Planning draws upon comparisons to previously learned behaviors and Organize makes use of sensory feedback Initiation: sending the plan down the spinal cord, and Predict Decision Evaluate out of the CNS Initiation CNS and motor control The plan ‘encoded’ into a precise pattern of electrical signals thousands of motor neurons such that when the plan reaches the muscles → effective movement is carried out Both planning and initiation phases must take into account that as the signal descend from CNS to PNS, changes are made along the way Areas of the brain The brain is divided into the: cerebrum cerebellum Cerebrum diencephalon brainstem Diencephalon Cerebellum Brain Stem Midbrain Pons Medulla oblongata The Cerebrum The cerebrum Left and right hemispheres Deep area underneath the cortex Outer/superficial area: cerebral cortex Cerebral cortex Cerebral cortex: houses our conscious mind, stores learned experiences and receives sensory inputs The Cerebrum - Lobes The cortexes can be anatomically divided into lobes Frontal lobe (anterior) Parietal lobe (top) Occipital lobe (dorsal) Temporal lobe (lateral sides)  The Cerebrum – Brodmann Areas The cortexes can be anatomically and functionally divided into Brodmann areas Most important Brodmann areas in motor control Motor cortex Somatosensory cortex Auditory cortex Visual cortex Areas that regulate conscious thought and executive function located in frontal lobe  Motor and Somatosensory cortex The motor and somatosensory cortexes can be mapped to correspond to body areas Homunculus Large amount of brain tissue devoted to motor and sensory function of the hands and face  Motor Cortex The motor cortex makes connections with the spinal cord via neuron tracts A key tract is the pyramidal tract, others are called extrapyramidal tracts Most tracts *decussate, so that one side of the brain corresponds to the opposite side of the body *Cross or intersect each other to form an X  Motor Cortex Upper motor neuron makes direct connection with the lower motor neuron in the spinal cord Lower motor neurons connect to muscles To muscle ←  Somatosensory Cortex Somatosensory cortex receives sensory information from the body (e.g., proprioception and touch) Makes connections with the spinal cord via neuron tracts most decussate Sensory tracts are more complex and varied than motor tracts  Cerebrum: deep Basal ganglia Processing information Posture and equilibrium Corpus callosum Links the left & right hemispheres  Measuring the brain Structure MRI CT Function fMRI EEG PET  Diencephalon The Thalamus Processes information flowing between the brain stem and the cerebrum Thalamus (mostly sensory) Also relays information among the motor cortex, basal ganglia, and cerebellum Diencephalon regulates many aspects of the autonomic nervous system  Cerebellum - the ‘little brain’ Involved in the planning and organizing of smooth, coordinated movements Compares movement plans to incoming sensory information Fine tunes movement for timing and precision Important for motor functions like walking and speaking Cerebellar ataxia Brain stem Sits at the junction of the brain and spinal cord Includes midbrain, pons, and medulla oblongata Acts as a passageway and switchboard for all fibers between the spinal cord and the cerebrum Processes, filters, and routes the signals Brain Stem Midbrain Pons Medulla oblongata Brain stem – reticular formation Houses a neural network Controls programmed, automatic movement behaviors Locomotion, posture, muscle tone Autonomic functions such as regulation of breathing and heart rate Automatic control of posture without being part of movement goal Learn more about the experiment here.  Spinal cord Links the CNS with the PNS White matter (myelinated axons) Gray matter (cell bodies from PNS neurons and interneurons) Sensory info – Dorsal root Movement commands – Ventral root Spinal cord In the spinal cord Motor commands multiple sensory inputs (multimodal inputs) meet up with motor neurons, in a process called sensorimotor integration. Sensory info CNS adaptations to Practice and Training Practice and training influence CNS structure and function Neuroplasticity (brain and spinal cord) Structure (e.g., new synapses) Function (e.g., altered somatotopic map) Practice: Training: learning and improving a skill physiological adaptation CNS adaptations to Practice CNS changes from postural control training CNS adaptations to Practice After days or weeks of motor skill practice, generally less brain area is active during performance of the task Reflects automaticity and improved efficiency In some cases more brain areas are active after learning, particularly interconnectivity Use of previously unused resources to maximize movement capability  CNS adaptations to Practice Changes reflect: Efficiency/automaticity Different strategies/purpose Following hundreds of practice trials: Blue = Regions of the brain that decreased in activity Orange = areas that increased in activity Permission from Gobel et al. (2011). Neuroimage, 58(4), 1150–1157. Elsevier Publishers.  CNS adaptations to Practice Changes in regional areas of use reflect changes in neural structure in the brain and spinal cord. More synaptic connections and dendritic sprouting More neurotransmitters and receptor sites More efficient neurotransmitter receptor sites Faster firing Growing of new neurons (neurogenesis) Areas of the motor cortex corresponding to the practiced muscles may get bigger, denser and more excitable  CNS adaptations to Training Psychological effects Exercise associated with improved mood, reduced anxiety and improved self-efficacy Cognitive health strategy in elders: improved cognitive function, memory and learning Physiological adaptations to exercise  CNS adaptations to Training Physiological adaptations to exercise Brain-related changes to training: Cell proliferation Increased blood flow Alterations in brain chemistry/neurotransmitters receptors synapses capillarization An overall slowing of brain tissue loss Changes in areas of brain activation Altered CNS Functioning: Central Fatigue Fatigue Inability to produce the required or expected force or work Muscle fatigue Failing muscle physiological and biochemical mechanisms Central fatigue Brain and spinal cord reduce motor output Measuring Central Fatigue Maximum voluntary isometric contraction (MVIC)  Measuring Central Fatigue Peak MVIC Central activation ratio (CAR) = Peak MVIC + Stim Max contraction with muscle stimulation Causes of Central Fatigue Glycogen depletion faltering neurotransmitter regulation loss in central drive from lowered oxygen levels. Nonmotor areas in the brain may begin integrating signals differently, Alters sensations and behavioral states, Leading to poorer motor performance