©2011 mcgraw-hill higher education. all rights reserved chapter 4 neuromotor basis for motor...

©2011 McGraw-Hill Higher Education. All rights reserved

Chapter 4Chapter 4

Neuromotor Basis for Motor Control

Concept: __________________________________________________________________________________


IntroductionIntroduction

________________________________•Components of the central nervous system

(CNS) and peripheral nervous system (PNS) involved in the control of coordinated movement


The NeuronThe 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


Types and Functions of NeuronsTypes and Functions of Neurons

Three Types of Neurons1. _________________________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


Types and Functions of Neurons, cont’dTypes 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


Types and Functions of Neurons, cont’dTypes 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


Central Nervous System (CNS)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


Brain Components: 1. CerebrumBrain 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


__________________________________________________

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


Cerebral Cortex, cont’dCerebral 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



Location & Structure

•Frontal lobe just anterior to central sulcus

•___________________________________________________________

FunctionInvolved in control of:

•Initiation and coordination of movements for fine motor skills

•____________________________

Primary motor cortex [see Fig. 4.4]



_____________________[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)

____________________________________ ____________________________________



_____________________________(SMA)•Location: Medial surface of frontal lobe

adjacent to portions of the primary motor cortex•Functions include involvement in the control of

__________________________________ __________________________________ ___________________________________



_______________________[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


Subcortical Brain Area Important in Motor ControlSubcortical 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


Basal Ganglia, cont’dBasal Ganglia, cont’d

____________________________•Common disease associated with

basal ganglia dysfunctionLack of dopamine production by

substantia nigra•Motor control problems [BART]

Bradykinesia (_____________________)Akinesia (________________________)Rigidity of musclesTremor


Brain Components: 2. __________________________Brain Components: 2. __________________________ 2nd 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


Brain Components: 3. _________________________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


Brain Components: 3. Cerebellum , cont’dBrain 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)

•__________________________________


Brain Components: 4. BrainstemBrain 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


__________________________________________________

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


________________________________________________________________

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


______________________________________________________________

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


______________________________________________________

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 movementse.g. eye muscles = 1 fiber / motor unit Gross movementse.g. posture control = many fibers (up to ~ 700) / motor unit


________________________________________________________________

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


From Intent to Action: The Neural Control of Voluntary MovementFrom 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


From Intent to Action: Brain Structures Associated with MovementFrom 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

©2011 mcgraw-hill higher education. all rights reserved chapter 4 neuromotor basis for motor...

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