1. ©2011 McGraw-Hill Higher Education. All rights reserved Chapter 4 Neuromotor Basis for Motor Control Concept: _________________________________________ _________________________________________

2. ©2011 McGraw-Hill Higher Education. All rights reserved Introduction ________________________________ Components of the central nervous system (CNS) and peripheral nervous system (PNS) involved in the control of coordinated movement

3. ©2011 McGraw-Hill Higher Education. All rights reserved The Neuron _____________________ = Nerve cell Basic component of the nervous system Range in size from 4 to 100 microns General Structure [see Fig. 4.1] _______________________  Contains nucleus _______________________  Extensions from cell body – range from 1 to thousands per neuron  Receive information from other cells ________________________  Extension from cell body – one per neuron with branches (known as collaterals)  Sends information from neuron

4. ©2011 McGraw-Hill Higher Education. All rights reserved Types and Functions of Neurons Three Types of Neurons 1. ___________________ ______ Also known as “afferent” neurons Send information to CNS from sensory receptors Unipolar – ______________________ Cell body and most of the axon located in PNS; only axon central process enters CNS

5. ©2011 McGraw-Hill Higher Education. All rights reserved Types and Functions of Neurons, cont’d 2._____________________ [see Fig. 4.2] Also known as “efferent” neurons Two types influence voluntary movement: 1. ___________________________  Predominantly in spinal cord – axons synapse on skeletal muscles 2. ___________________________  In intrafusal fibers of skeletal muscles

6. ©2011 McGraw-Hill Higher Education. All rights reserved Types and Functions of Neurons, cont’d 3. __________________ [see Fig. 4.2] _______________________________ ________________________________ Function as connections between:  Axons from the brain and synapse on motor neurons  Axons from sensory nerves and the spinal nerves ascending to the brain

7. ©2011 McGraw-Hill Higher Education. All rights reserved Central Nervous System (CNS) Two components: Brain and spinal cord _________________ 4 structural components most directly involved in the control of voluntary movement: 1. ____________ 2. ____________ 3. ____________ 4. ____________ See Figure 4.3

8. ©2011 McGraw-Hill Higher Education. All rights reserved Brain Components: 1. Cerebrum One of two components of forebrain Two halves _______________________ Covered by cerebral cortex Gray tissue; 2- to 5-mm thick Undulating covering of  ______________ – each is called a gyrus  ______________ – each is called a sulcus Cortex motor neurons  ________________________ Connected by the corpus callosum

9. ©2011 McGraw-Hill Higher Education. All rights reserved _________________________ Four lobes [see Fig. 4.3] __________ ______________________ [see Fig. 4.4] Posterior to central sulcus Receives neuron axons specific to type of sensory information Named according to nearest skull bone

10. ©2011 McGraw-Hill Higher Education. All rights reserved Cerebral Cortex, cont’d ________________________ [see Fig. 4.4] Location Adjacent to specific sensory areas of sensory cortex Function To “associate” information from the several different sensory cortex areas __________________________________________ ____________________________________________  e.g., selection of the correct response in a choice- RT situation Possible locations for transition between perception and action

11. ©2011 McGraw-Hill Higher Education. All rights reserved Cerebral Cortex, cont’d Location & Structure Frontal lobe just anterior to central sulcus ______________ _______________ _______________ _______________ Function Involved in control of: Initiation and coordination of movements for fine motor skills _____________ _______________  Primary motor cortex [see Fig. 4.4]

12. ©2011 McGraw-Hill Higher Education. All rights reserved Cerebral Cortex, cont’d _____________________ [see Fig. 4.4] Location: Anterior to the primary motor cortex Functions include  Organization of movements before they are initiated  ____________________________________ -- enables transitions between sequential movements of a serial motor skill (e.g. keyboard typing, piano playing)  ____________________________________ ____________________________________

13. ©2011 McGraw-Hill Higher Education. All rights reserved Cerebral Cortex, cont’d _____________________________(SMA) Location: Medial surface of frontal lobe adjacent to portions of the primary motor cortex Functions include involvement in the control of  __________________________________ ___________________________________

14. ©2011 McGraw-Hill Higher Education. All rights reserved Cerebral Cortex, cont’d _______________________ [see Fig. 4.3] Location One of the 4 lobes of the cerebral cortex Function ______________________________ ________________________________  Interacts with the premotor cortex, primary motor cortex, and SMA before and during movement

15. ©2011 McGraw-Hill Higher Education. All rights reserved Subcortical Brain Area Important in Motor Control ___________________________ Buried within cerebral hemispheres Consist of 4 large nuclei  _________________ Function involves control of  ____________________________________ - Receive info from cerebral cortex and brainstem - Send info to brainstem

16. ©2011 McGraw-Hill Higher Education. All rights reserved Basal Ganglia, cont’d ____________________________ Common disease associated with basal ganglia dysfunction  Lack of dopamine production by substantia nigra Motor control problems [BART]  Bradykinesia (_____________________)  Akinesia (________________________)  Rigidity of muscles  Tremor

17. ©2011 McGraw-Hill Higher Education. All rights reserved Brain Components: 2. __________________________ 2 nd component of forebrain [See Fig. 4.3] Contains two groups of nuclei _____________________  Functions: A type of relay station - receives and integrates sensory info from spinal cord and brainstem; sends info to cerebral cortex _______________________________________ ________________________________________ _______________________  Critical center for the control of the endocrine system and body homeostasis

18. ©2011 McGraw-Hill Higher Education. All rights reserved Brain Components: 3. _________________________ Location: Behind cerebrum and attached to brainstem [See Fig. 4.3] Structure includes _______________________ ________________________ ___________________________________ ____________________________________  Red nucleus – Where cerebellum’s motor neural pathways connect to spinal cord  Oculomotor nucleus

19. ©2011 McGraw-Hill Higher Education. All rights reserved Brain Components: 3. Cerebellum, cont’d Functions ___________________________________ ____________________________________  Clumsy movement results from dysfunction ___________________________________ ____________________________________ Serves as a type of movement error detection and correction system  Receives copy of motor neural signals sent from motor cortex to muscles (efference copy) __________________________________

20. ©2011 McGraw-Hill Higher Education. All rights reserved Brain Components: 4. Brainstem Location Beneath cerebrum; connected to spinal cord [See Fig. 4.3] 3 components involved in motor control _______________ ________________ Functions ______________ Involved in control of various body functions (e.g. chewing) and balance ______________ Regulatory center for internal physiologic processes (e.g. breathing) _________________ Integrator of sensory and motor info Inhibits / Activates neural signals to skeletal muscles

21. ©2011 McGraw-Hill Higher Education. All rights reserved _________________________ A complex neural system vitally involved in motor control Structure [See Fig. 4.5] _____________– H-shaped central portion  Consists of cell bodies and axons of neurons  Two pairs of “horns” ________________________– Cells transmit sensory info ________________________– Contains alpha motor neurons with axons terminating on skeletal muscle  Interneurons (Renshaw cells) – In ventral horn

22. ©2011 McGraw-Hill Higher Education. All rights reserved ________________________________ Several neural tracts (called _________________) Pass through spinal cord and brainstem Connect to sensory areas of cerebral cortex and cerebellum 2 tracts to sensory cortex especially important for motor control _____________________________ Tract to cerebellum important for motor control ______________________________– Primary pathway for proprioceptive info

23. ©2011 McGraw-Hill Higher Education. All rights reserved _______________________________ Called ______________________________ Travel from brain through spinal cord ____________________(corticospinal tracts) 60% from motor cortex Most fibers cross to other side body (decussation) in medulla of brainstem Involved in control of fine motor skill performance ____________________(brainstem pathways) Fibers do not cross to other side of body Involved in postural control and control of hand and finger flexion – extension

24. ©2011 McGraw-Hill Higher Education. All rights reserved ___________________________ An alpha motor neuron and all the skeletal muscle fibers it innervates [See Figure 4.6] When a motor neuron activates (fires) all its connected muscle fibers contract The ultimate end of the motor neural information ~ 200,000 alpha motor neurons in spinal cord Number of muscle fibers served by a motor unit depends on type of movement associated with the muscle  Fine movements e.g. eye muscles = 1 fiber / motor unit  Gross movements e.g. posture control = many fibers (up to ~ 700) / motor unit

25. ©2011 McGraw-Hill Higher Education. All rights reserved ________________________________ Amount of force generated by muscle contraction depends on number of muscle fibers activated To increase force, need more motor units _____________________________________ _____________________________________ Recruitment follows “size principle” Size = ___________________________________ _____________________= recruit smallest motor units first (i.e., weakest force produced) then systematically increase size recruited until achieve desired force

26. ©2011 McGraw-Hill Higher Education. All rights reserved From Intent to Action: The Neural Control of Voluntary Movement Think about the entire process of deciding to perform a skill and actually performing it The neural activity involved in this process typically follows a hierarchical organization pattern From higher to lower levels of the neuromuscular system This process is described conceptually in Figure 4.7 and Table 4.1 Discuss this figure and table for the performance of a specific motor skill

27. ©2011 McGraw-Hill Higher Education. All rights reserved From Intent to Action: Brain Structures Associated with Movement Research by Carson and Kelso (2004) Demonstrated: More involved in knowing how we control voluntary coordinated movement than knowing which brain structures involved in which type of movements Cognitive intention is a critical component Experiment Participants performed finger-flexion movement to a metronome On the beat (synchronize) Between beats (syncopate) Task involved exactly the same movement but two different cognitive intentions fMRI results showed Different brain regions active for the two movement intentions