dezvoltarea fizica si biologica Flashcards
How many neurones does the human adult brain have?
86 billion neurones - number of trees in the Amazonian rain forest
51 trillion synapses - number of leaves in the Amazonian forest
Many of the neurones are created during prenatal brain development
What are the postnatal brain developments? synapses
Proliferation of synapses- increase in synaptic connections
Then there is synaptic pruning and cell death - infant is habituated to the world that is growing up in, realising that you don’t need all connections
There is reduction in grey matter across the brain into adolescence
What are the postnatal brain developments? - myelination
The axon gets coated with fat that helps electrical signal more quicker.
Myelination happens at different points across development.
At least 20 years to fully grow brain.
New cells and connections develop throughout life.
How does functional specialisation develop?
Brain areas are functionally specialised for certain tasks.
E.g. occipital lobe specialised for visual processing
How does functional specialisation for face perception develop?
Perceptual narrowing of face differentiation in infancy
6 m.o.- able to discriminate between both human faces and monkey faces
At 10 m.o. babies were only able to discriminate between human faces
Adults show specific response to upright human faces
Might reflect specialisation of the fusiform face area
But shouldn’t be called fusiform face areas because there has been shown activation for other things as well such as a shepard being able to tell apart his sheep
What have fMRI studies shown about the development of face specialisation?
fMRI studies show that the brain areas involved in face processing continue to develop across childhood and adolescence
What are reflexes and U-shaped development?
Strong reflexes disappear and later get replaced by more specific motor behaviours.
At birth, reflexes are strong and automatic
At 2 months they disappear
Later, they re-emerge to become more intentional and controlled
What is an explanation for the U-shaped development?
Brain maturation
Early reflexes are mediated by sub-cortical structures (brain stem/spinal cord)
Disappearance of these reflexes might be associated with maturation of the cerebral cortex which leads to an inhibition of the sub-cortical reflex mechanisms by higher brain areas
Controlled walking is relearned by the cortical structures.
What is another explanation for the U-shaped development?
Stepping reflexes disappear at 2 months but kicking reflex increases
Showed a rship between the mass of an infant’s legs and the disappearance of the reflex
Stepping in young babies disappeared if weights were added, and reappeared in older babies when they were placed in water.
Changes in body weight determine the disappearance of the stepping response
What is Occam’s razor?
Entities should not be multiplies before necessity.
Take the simplest solution
What are hormones?
Hormones are regulatory biochemicals which change in their prevalence across development.
What is hormonal development?
Adolescence is a particular time when hormones may play an important role.
Changes in grey matter is associated with puberty and hormonal changes.
What is the role of genes in development?
There are some developmental disorders with clear genetic origins.
However, genetic effects are usually polygenic (related to more genes)
What is the meaning of pleiotropic?
Genetic influences can be pleiotropic - one gene can have an impact on many different phenotypes which is why we often see comorbidity
What is epigenetics?
The study of how genes become expressed.
