Week 7 (8) Flashcards
What are reflexes?
- involuntary stereotyped movement responses to a particular stimulus
- reflexes begin prenatally due to maturity of CNS (brainstem and midbrain)
- ~27 reflexes at birth
- some stay throughout life
What are are the 5 things to know about the purpose of reflexes?
- built-in responses to c=facilitate survival
- allow “dialogue” with environment
- reflexive movements result in sensory consequences (adaptation)
- provide building blocks for future movement
- sometimes no clear relevance at birth
What are the 3 main types of reflexes?
primitive, postural, and locomotor
What are primitive reflexes? What are the ones to know?
- survival and protection
- sucking, rooting, moro, asymmetric tonic neck reflex, symmetric tonic neck reflex, palmar grasp reflex
What are primitive reflexes? What are the ones to know?
- react to gravitational changes in equilibrium
- labyrinthine righting reflex, pull-up reflex, parachute reflex
What are locomotor reflexes? What are the ones to know?
- for travel and navigating envrionment
- crawling reflex, stepping reflex, swimming reflex
What is the sucking reflex? What is the purpose and timetable?
- purpose: meet feeding needs
- stimulated by lip touch
- develop coordination in sucking, breathing, and swallowing
- timetable: 4th prenatal month to b-9th postnatal month
What is the rooting reflex? What is the purpose and timetable?
- purpose: seeking food and prep for feeding
- stimulated by cheek touch
- timetable: birth to 9th month
What is the moro reflex? What is the purpose and timetable?
- purpose: self-protection from body imbalance or sudden stimulation
- stimulus: starts in supine postion, and startle (e.g. tap a pillow) or stimulate falling
- response: arms and legs extend outward, and then flex
- timetable: 7th prenatal month to 3rd postnatal month
What is the asymmetrical tonic neck reflex? What is the purpose and timetable?
- purpose: for developing hand-eye coordination
- stimulus: start infant in supine position → turn head to one side
- response: same side arm and leg extend; flex on opposite side
- timetable: 7th prenatal month to 5th month postnatal
- no clear relevance at birth
What is the symmetrical tonic neck reflex? What is the purpose and timetable?
- purpose: allow independent movement of upper and lower body parts, preparing for coordinated movement
- stimulus: place in crawling position and flex head; response: arms flex and arms extend
- stimulus: place in crawling position and extend head; response: arms extend and legs bend
- timetable: 7th prenatal month, prominent at 5-6th postnatal months, integrated by 10th-11th month
What is the palmar grasp reflex? What is the purpose and timetable?
- purpose: to practice clenching hands, prepping for later grasp movements
- stimulus: touch palm with finger or object
- response: hand closes tightly around finger or object
- grip is strong enough to hold most of baby’s weight
- timeline: birth to 4-6 months
What is the labyrinthine righting reflex? What is the purpose and timetable?
- purpose: corrects orientation of body when it’s taken out of position
- stimulus: while infant is supported upright, tilt infant
- response: head moves to stay upright
- timeline: 2 months postnatal to 1 year
What is the parachute reflex? What is the purpose and timetable?
- purpose: protect and support when off balance
- stimulus: infant is held upright, and lower them toward the ground quickly
- response: legs and arms extend
- timeline: 5-6th postnatal months to 1 year
What is the crawling reflex? What is the purpose and timetable?
- purpose: prep for voluntary crawling later in development
- stimulus: in prone position, apply pressure to toes
- response: infant will push off opposing legs and arms
- timeline: birth to 4 months
What is the locomotor reflex? What is the purpose and timetable?
- purpose: prep for voluntary walking later in development
- stimulus: holding infant upright, put pressure on bottom of feet
- response: knee lifts as if initiation walking movement
- timeline: birth to 2-3 months
What is the swimming reflex? What is the purpose and timetable?
- purpose: prep for voluntary swimming later in life
- stimulus: hold infant above water with head up
- response: infant will move arms and legs rhythmically
- timeline: birth to 6 months
What is the 1st view in linking reflexes to voluntary movement?
stimulation transforms reflexes to voluntary actions
- reflexes become voluntary actions through training
- compared infants who practiced walking through stepping reflex with those that didn’t → walking emerged earlier in those who practiced stepping reflex
What is the 2nd view in linking reflexes to voluntary movement?
voluntary movement emerges from reflexes after development of multiple subsystems
- reflex disappears and reappears as voluntary movement when subsystems are developed
- changing constraint can result in disappearing of stepping reflex
- with young infants who were still reflex-stepping: added small weights to their ankles → decreased stepping reflex
- with older infants who no longer reflex stepped: submerged them in water → water’s buoying effects simulated increase in strength → infants stepped with greater frequency
What are rate controllers?
- a constraint that prevents the development of a movement pattern
- e.g. rate controllers involved in walking may include balance systems, leg strength, force production
Do spontaneous movements (stereotypies) result from external stimuli?
No
What are spontaneous movements?
- transitional behaviours: some level of control but not intentional or goal-directed
- early stereotypies: leg kicking, arm waving, arm banging, finger flexion
- later stereotypies: arching the back, rocking, bouncing while standing
- posture will influence movement frequency
The beginnings of voluntary movement is known as?
rudimentary behaviour
What is rudimentary behaviour?
- highly influenced by environment (stimulation and affordances)
- cephalocaudal-proximodistal direction of development
- 4 E’s: embodied, embedded, enculturated, enabling
What are the 4 E’s in rudimentary behaviour?
embodied: current state of the body will influence what actions one can do
embedded: the environment will offer constraint action possibilities
enculturated: social and cultural influence shape actions
enabling: new motor skills create opportunities to learn and explore
What is postural control?
ability to detect changes in body’s center of gravity in relation to the base of support
- head control, rolling, sitting, standing
Describe rudimentary locomotion
- at 3 months, scoot while sitting
- at 6 months, crawling, creeping, edging sideways, crab walking
- at 8 months, can stand, cruise while holding on to objects, move sideways
- at 13 months, walking
What are prehension and manipulation in manual control?
prehension: using hands to reach, grasp, release (first 2 years)
manipulation: using hands to skillfully with object(s) (after 2 years)
What is non-goal directed behaviour in motor control?
- emerge prenatally/birth
- appear as reflexes and spontaneous movements
What is goal-directed behaviour in motor control?
- emerge after improved postural control and stability
- initial movements are shaky but become smoother over time → make corrections as they perform movements more and as level of control changes
What is the development sequence for any small object
- releasing grasp is difficult, can take 18 months
What is the development sequence for grasping large object?
- reach with one hand only
- reach with one hand and then the other
- bimanual, reach with both hands at once
What is the development sequence for grasping force application?
- at first, force and object weight are unrelated
- can adjust force after initially grasping an object
- then, can adjust force after judging objects
What is motor asymmetry?
- the paired limbs (hands, feet) and sensory organs (eyes, ears) used asymmetrically (right hemisphere motor and sensory activity paired with left half of the body
- left hemisphere has a complementary role in conscious movement on the right side of the body
- lateral preference and lateral (hemispheric) dominance
Why are majority of people right handed?
right-shift theory
- right-shift gene is dominant
- environment may influence limb preference in those with weaker right shift gene
- left hemisphere matures faster than right hemisphere, biasing more right-handed preference
- environment and culture can modify limb preference
