Movement Science Week 9

Movement

Interaction of perception and action systems, with cognition affecting both systems at a different level

Movement Control

Cooperative effort of many brain structures organize hierarchal and in parallel

Spinal Cord

-Lowest level of perception/action hierarchy

-Initial reception and processing of somatosensory info

-Reflex and voluntary control of posture and movement through motor neurons

Brainstem

-Contains nuclei involved in postural control and locomotion: vestibular, red, and reticular nuclei

-contains ascending and descending transmitting pathways transmitting sensory and motor info to CNS

Cerebellum

-Lies behind brainstem: connected by peduncles

-Recieves inputs from spinal cord and cerebral cortex

-important functions in motor control

Diencephalon

Contains thalamus and hypothalamus

Cerebral hemisphere

Basal Nuclei: higher-order cognitive aspects of motor control (planning of motor strategies)

Cerebral cortex: highest level of motor control hierarchy (identifying targets in space, choosing course of action, and programming movements)

Neuron

Basic unit of CNS

-Lowest level in hierarchy: single neuron in spinal cord

-Always has negative electrical charge or potential inside the cell

-communicates through synaptic transmission

Somatosensory peripheral receptors

-Muscle spindle

-Golgi tendon organs

-joint receptors

-cutaneous receptors

Somatosensory system parts

-Ascending pathways (ML, anterolateral system)

-Thalamus

-somatosensory cortex

-association cortices

Visual System

-Exteroceptive sense: identify objects in space and determine their movement

-Visual proprioception: where body is in space, relation of one body part to another, and motion of the body

Peripheral visual system

-light enter eye through cornea and focus by cornea and lens on retina at the back of the eye

-Photoreceptor cells: rods and cones

-Cones: functional for daylight vision; responsible for color vision

-Rods responsible for night vision

Vestibular system

-Position head in space

-sudden changes in direction of head movement

-important for coordination of motor responses

-peripheral: sensory receptors and CN VIII

-Central: 4 vestibular nuclei, ascending and descending tracts

Motor Cortex

-Involved in planning, coordinating, and executing goal-directed voluntary movement

-Comprised of the Primary motor cortex, premotor cortex, and supplementary motor area

-Areas work together as a functional unit with distinct roles

Primary motor cortex

-primarily responsible for executing motor plan; encodes things like movement force, direction, speed, amplitude

-send descending signals that will eventually lead to individual muscle actions

-copy of motor command sent to other areas

Premotor cortex

-Send signals to PMC and spinal cord directly

-appears to be involved in motor plan selection

-may also play role in movement preparation

-also tends to be active when viewing familiar movements

Supplementary motor area

-Appears to be involved in voluntary movements and movement sequences

-The lateral premotor area controls movements activated by external stimuli

Association Areas

-integrating info from different regions

-Posterior parietal cortex integrates visual, tactile, and proprioceptive info

-Plays key role in attention and perceptual awareness

-signal from PPC sent to premotor area and prefrontal cortex

Cerebellum Actions 1

-coordination of movement

-does not play primary role in motor function

-regulates motor out put: receives info from other areas of brain in regards to planning and executing movement

-input and output connections are critical for error detection

Cerebellum Actions 2

-info from PMC for motor plans sent to spinal cord

-Copy of plan sent to cerebellum

-sensory feedback received about movement as they occur

-cerebellum compares copy to what actually happens

-info then sent to motor cortex and other system within brain stem to modify output

Basal nuclei

-Basal ganglia comprised of a group of subcortical structures

-Exact role in motor control is still not fully understood

-appears to be a likely role in initiation of self-directed movements and inhibiting unwanted movments

Mesencephalon and brainstem

•Generation of locomotor rhythms

•Regulation of postural tone

•Integration of sensory information for posture and balance

•Contributions to anticipatory postural control accompanying voluntary movements

vestibular system receptors

-3 semicircular canals

-Utricle

-Saccule

Central receptor: vestibular nuclei