Newborns and reflexes Flashcards
What event led to different types of mammals increasing?
The extinction event of the dinosaurs.
What does Cretaceous period mean?
Reptiles ruling the earth
What is an example of adaptive radiation?
Bc of increased survival rates, organisms diversified + adapted to new/recently vacated ecological niches after the dinos died.
True or False
There was not many mammalian species 65 million years ago
True
Describe Endothermy as mammalian physiology
Endothermy = warm-blooded, requires high-energy food + thermoregulatory adaptations (fur)
Describe Live Births as mammalian physiology
Mammary glands, adaptions for nursing, and protection from predators (parenting) is a consequence of evolutionary adaptations, signalling behaviours (crying)
Finish the sentence…
‘Mammalian physiology can be seen as physiological and…’
Behavioural adaptions to survival
True or False?
Humans are not primates
False
How are human infants advanced compare to other mammals
Compared to cats born with their eyes sealed shut = babies, eyes + ears are not sealed.
Compared to rats with ~25% = babies are born with nearly complete neural cell perforation.
Compared to ungulates (horses) who are faster and marsupials (kangaroos) = babies have moderate rapid locomotor development
How are infants altricial (slow-developing) compared to other mammals?
Infants = dependent on mothers up to 4 years
Very extended juvenile life stage = delayed adolescence/ reproductive maturity
How do humans compare to chimpanzees in reproduction?
Humans = unusual in having a significant post-reproductive life span (menopause) whereas chimps reproduce throughout their lives
Complete the sentence
‘Infants have reflexes linked to …’
Evolutionary primate heritage
What sensory capabilities do new borns have?
All the five senses and balance
What types of touch can babies feel at birth?
Pain
Pressure
Proprioception = awareness of the movement of the body
Changes in temp
How is a baby’s balance at birth?
They have a well-developed vestibular system
What types of taste can babies feel at birth?
Salty
Bitter
Sweet
Sour
What types of hearing can babies feel at birth?
Lower frequency and their ability to localise sound improves during the first 7 years of life
What types of vision can babies have at birth?
Very poor
20/400 at birth
improves to 20/20 at 6 months
What does vestigial mean in relation to reflexes?
Some reflexes as evolutionary holdovers. Reflexes exist in the repertoire of newborns, but they have partially or wholly lost their original function.
What are some orientating responses within neonatal bhvral repertoires?
Visual tracking
Auditory tracking
What are some reflexes within neonatal bhvral repertoires?
Clinging = palmar & plantar grasp, Moro reflex -> human mums don’t have fur
Nursing = rooting, sucking
Locomotion = crawling, stepping
What is the rooting reflex?
If you brush the side of the mouth of a new-born. They will turn their head bc they anticipate a nipple/ insert finger or bottle into the mouth, and they will suck
What is the Moro reflex?
Help babies cling to their mothers for safety + protection. If they hear a large bang, they will go to their mothers. Disappears @ 6mths
What type of phenomena is neonatal relflexes?
A lower brain stem phenomena
What is the Babinski reflex?
Function unknown, stroking baby’s foot from toe to heal and whether the toes curl. Can indicate brain damage.
Who is Terry Brazelton?
He invented the clinical assessment of newborns. Neonatal Behavioural Assessment Scale ‘Brazelton scale.’
Infant chimps have similar reflexes, but how do they differ?
Human brain growth after birth is significantly larger than in chimpanzees.
Humans have additional cells in the brain = glial cell
Uniquely big brains 400g @ birth, 1300 in adult hood
What is a glia cell?
Non-neuronal cells in the central nervous system maintain homeostasis, provide structural support, and insulate neuronal axons w/ myelin. Most neurons present @ birth, but glia continue to multiply
What is myelination?
Is the production or formation of fatty sheathes around axons. This increases the transmission of action potentials in human brains.
What is the speed for myelinated?
~10-100m/second
What is the speed for unmyelinated?
~1m/second
In the peripheral nervous system, which cells lay down the myelin sheath
Schwann cells
In the central nervous system, which cells lay down the myelin sheath
oligodendorcytes
What is Synaptogenesis?
The formation of new connections between neurons (new synapses) = no. of axon terminals + dendrites increases in the first and 2nd year of life.
Dendritic growth in Broca’s area support this, showing the no. of cell bodies stay the same but the density of dendritic spines increases
What is a synapse?
junctions between the terminal of a neuron + another neuron/muscle/gland cell which nerve impulses pass
When does growth peak in the cortices for synaptogenesis
Visual cortex =~12 months
Auditory cortex = ~3 years
Prefrontal cortex = ~3 years
New connections are the most rapidly made in the early life.
How does Hubel and Wiesel (1950s) show evidence for critical and sensitive periods in brain development
Found that 80% of neutrons were activated from input from both eyes (binocular).
Sewed one eye of kittens and removed it at 2.5 mths old. Once removed, found kittens were functionally blind from the sewed eye for the rest of their life.
This shows humans need specific stimulation for typical brain development within a specific period - evidence for humans. Cataract surgery = 3-7 years of life for optimal results.
How does extreme neglect affect brain development
Child Trauma Academy by Perry, CT of 3 yrs old vs control 3yrs old. Showed brains were smaller.
Children’s Hospital of Michigan = PET scan of 9yrs old Romanian orphan vs control child. Showed reduced glucose (metabolic) activity in prefrontal + temporal regions. Shows an overall change in brain functioning + growth.
