Chapter 4: Early 1 and 2 Flashcards
Recall the maturational perspective on development suggests the brainstem/spinal cord, midbrain and cerebral cortex affects what reflexes/reactions?
Recall the maturational perspective on development
Brainstem/Spinal Cord → Primitive reflexes
MidBrain → Righting reactions
Cerebral cortex → equilibrium reactions
As the brain develops, the maturational perspective suggests that the CNS was the sole constraint to guide early motor behavior which implies?
unidirectional control
Is this really the case?
it seems not. Recent evidence suggests that movement also affects brian development (again, the interaction is key)
This helps to explain movements that had not really been considered by aerie er researchers: Those that appear randomly, or spontaneously
Are the random movements reflexive?
No
They occur in the absence of any apparent stimulus (or for any apparent reason)
Spontaneous (Steretypie) movements
Spontaneous Movements
Are the infants movements that occur without any apparent stimulation
Examples: Supine kicking, spontaneous movements
who studied supine kicking?
Thelen and Colleagues (1985, 1995)
Thelen et al. studied spine kicking movements by analyzing position and timing of limb segments what did they find?
Movements are not random
They are rhythmic and coordinated
Ankle, knee, and hip joints move cooperatively (not independently)
What does the patterns of the spontaneous movements of supine kicking in infants show?
These patterns appear to be early precursors of walking
How do infants tend to use their muscles?
Infants tend to co-contact their muscles (flexors and extensors contracted) adults are more efficient
Spontaneous arm movements (pre-grasp reaching) another stereotypies
Again, high degree of coordination of elbow, wrist, and finger joints
Note the fingers do not extend independently
Why do stereotypies exist?
Newborn musculature is underdeveloped
Lack of ability to produce intentional, goal-directed movements
Spontaneous movements og and current theory:
Original theory: movements are extraneous, with no purpose
Current theory:
Movements are “building blocks”, are similar to, and serve as a function for some voluntary movements
The developing brain results in the generation of these movements (maturational) the movements in turn shape the development of the brain (ecological)
These stereotypes are one example of early (pre-adaptive) motor behaviors. what is another movement that arises from this?
Another is movements that arise as the result of reflexes
Infantile Reflexes:
Reflexive movements occur quickly after the onset of stimuli
They involve single muscle or specific group of muscles (not the whole body)
They can not be extinguished at any one time
Persistence many indicate neurological problems
Are reflxes voluntary or involuntary?
involuntary after a stimulus
When do reflexes begin to develop?
Dominant movement from during the last 4 months of prenatal life (i.e begin to develop in utero) and the first 4 months after birth
Where in the brain to reflexes occur?
Occur subcortically (below the level of the higher brain centers)
Why do reflexes occur?
Built-in response, facilitates survival
Allows interaction with the environment
Reflexive movements result in sensory consequences, stimulate development
During later portion of reflexes period, reflex are modulated “building blocks” for future movement
How many reflexes?
There are approximately 27 major infantile reflexes (most are suppressed at about 4-6 months of age)
General Types of infantile reflexes:
Primitive: survival and protection
Postural: reaction to gravity
Locomotor: resemble voluntary locomotion
Asymmetric tonic neck reflex (primitive)
Infant starts in supine position stimulus : turn head to one side Response: same-side arm and leg extend Facilitates bilateral body awareness Facilitates hand eye-coordination Also called “bow and arrow” or “fencer’s” position
Symmetric tonic neck reflex
Infant starts sitting
Stimulus: tip forward
Response: neck and arms flex, legs extend (tip back, neck and arms extend, legs flex)
Faciliatest equilibrium (vestibular development)
Persistence may impeded many motor skills and cause spinal flexion deformities
Doll eye reflex
Infant starts in vertical position
stimulus: movement to supine and back to vertical
Response: Eyes open and close
Facilitates vestibular development
Triggers of sleep and alertness
Persistence after first few days may indicate a problem
Palmar grasping
Stimulus: touch palm with finger or object
Response: hand closes tightly around object
Moro reflex
Infant starts in vertical position
Stimulus: suddenly but gently lower babys head
Response: Arms and legs extend rapidly
May signify CNS dysfunction if lacking
May signify sensory motor problem if persists
May delay sitting and head control if persists
May indicate injury to one side of brain if asymmetrical
sucking reflex
Stimulus: touch face above or below lips
Response: sucking motion begins
Babinski reflex
Infant starts in any position
Stimulus: stroke sole of the foot from heel to toe
Response: toes fan out
Postural reflexes (postural reactions) facilitate?
posture maintenance in a changing environment
Maintain head in an upright position (breathing)
Aid in development of mobility (e.g., righting and rolling
Help to develop equilibrium with in motion (e.g, parachute)
When do postural reflexes typically appear?
after 2 months
Are postural reflexes sequential?
Yes, for example righting happens before rolling
What are the three postural reflexes?
Derotative righting reflex, Labyrinthine righting reflex, and Parachute reflex
Derotative righting reflex
Infant starts in supine position
Stimulus: turn head to one side, or turn legs and pelvis to other side
Response: Body follows head in rotation, or truck and head follow in rotation
Facilitates equilibrium reactions
Labyrinthine righting reflex
Infant starts in a supportive upright position
Stimulus: Tilt infant
Response: Head moves to stay upright
Necessary for bringing the body into an upright position and to orient in relation to gravity
Parachute reflex
Infant starts upright Stimulus: lower infant toward the ground rapidly Response: Legs extend (4 months) Tilt forward: arms extend (7 months) Tilt sideways: arm extend (6 months) Tilt backwards: arm extend (9 months)
Locomotor reflexes facilitate?
voluntary gait
when do locomotor reflexes appear?
They typically appear much earlier than the voluntary movement
They are rhythmic movements that begin to show classic elements of coordinated movement:
Crawling, stepping, swimming
Stepping reflex
Starting position: held upright
Stimulus: infant upright with feet touching surface
Response: legs lift and descend
Precursor to later voluntary walking
Disappears after approximately 5-months (unless you hold the child upright in water, the it reappears)
Swimming reflex:
Starting position: prone in water
stimulus : place infant in or over water
Response: swimming
Note the oscillation movements (like a tadpole)
Purpose of reflexes?
Some have clear reasons to emerge, others are less obvious
There roles have been described in 3 different ways:
Structural
Functional
Applied
Structural?
Reflexes are a byproduct of the developing neurological system (hardwiring)
Functional?
reflexes serve specific functions related to survival (ex, breath, eat)
Applied?
reflexes foreshadow volitional goal-directed movements
What is the current thought of infantile reflexes?
serve as building blocks to voluntary movement
Relationship between reflexes and voluntary movement
What do early researchers believe?
Early researchers (e.g McGraw) believed that voluntary movement was not possible until reflexes had been inhibited (motor interference)
A motor milestone:
Is a fundamental motor skill
Attaining this motor skill is associated with the acquisition of later movements
Relatively consistent stages of milestones
Timing can differ from individual to individual
Who are the motor milestone researchers?
Bayley (1936, 1969) Shirley (1931, 1963)
Motor milestone age range: 0.1-3.0 Bayley description
lifts head when held at the shoulder lateral head movement arm thrusts in play leg thrusts in play retains red ring (grasps)
Motor milestone age range: 0.1-3.0 Shirley
chin up (lifts head in prone)
Motor milestone age range: 0.7-7 Bayley
head lifts and steady
turns from side to back
sits with slight support
turns from back to side
Motor milestone age range: 0.7-7 shirley
chest up
sits with support
Motor milestone age range: 4-10 Bayley
partial thumb opposition sits alone momentarily unilateral reaching rotates wrist rolls from back to front
Motor milestone age range: 4-10 Shirley
sits on lap
grasps objects
sits in chair
Motor milestone age range: 5-10 Bayley
sits alone steadily
complete thumb opposition
pre-walking progression
partial finger prehension
Motor milestone age range: 5-10 Shirley
sits alone
stands with help
Motor milestone age range: 5-12 Bayley
pulls to standing
stands up by furniture
stepping movements
walks with help
Motor milestone age range: 5-12 Shirley
stands holding furniture
creeps
Motor milestone age range: 9-20 Bayley
stands alone
walks alone
walks backwards
Motor milestone age range: 9-20 Shirley
pulls to stand
stands alone
walks alone (shirley sequence ends here)
Motor milestone age range: 12-30+ Bayley
walks up stairs with help
walks down stairs with help
jumps off floor, both feet
jumps from bottom step
What other motor milestone researcher is there?
The WHO (2006) WHO multicenter growth reference study (MGRS) Group
The WHO 6 motor milestones
sitting w/out support, creeping, standing with assistance, walking with assistance, standing alone, walking alone
In terms of siting without support what are the differences
MGRS (WHO) = 5.9 months
Bayley = 6.6 months
Shirley = 7 months
In terms of standing without support what are the differences b/w studies
MGRS = 7.4 months Bayley = 8.1 months Shirley = 8 months
What can we conclude from these studies?
Infants are attaining the same motor milestones at approximately the same ages as infants did 80+ years ago
Postural control?
is the act of maintaining, achieving or restoring balance
How does CNS affect postural control?
Our CNS regulates sensory information from other systems in order to make adequate motor output responses to maintain a controlled, upright posture
How does the cerebellum affect postural control?
the cerebellum coordinates voluntary muscles movement’s and helps to maintain posture, balance and equilibrium
What is the developmentalists view of postural control?
postural control and balance are part of the rate limiting system
