Recovery from brain damageinjury destruction of

Recovery from brain damage/injury
 Destruction of neurons forces other neurons to take over the lost functions for recovery

Surviving neurons can restore functionality by modifying themselves structurally or
biochemically
o
Structurally: sprout new dendrites or extending axons to form new synapses
o
Biochemically: release more neurotransmitters
 Recent findings suggest that brains of mature primates and humans are capable of
producing new neurons (neurogenesis)

Brain is capable of greater plasticity early in life
o
Because 1 to 2 year olds have 50% more brain synapses than mature adults do

Unused or weaker synapses deteriorate or suicide with age, so brain loses its plasticity

Genetics – Heritability & Disorders 09/12/2013
October 10, 2013
°
Genetics of Behaviour: Nature vs. Nurture
° Nature: something we’re born with
° Nurture: something we learn
Genes: strand-like molecules of DNA that are linked on chromosomes
Karyotype: genetic blueprint

XY male XX female
°
Genes (DNA)  RNA  proteins molecules (sequences of amino acids)
°
° Protein synthesis can influence all your attributes. Genes influence protein synthesis, and
can help to determine the range of possibilities – not to what degree you will express them. There
are no genes for a particular attribute. There is no gene for intelligence, but many people measure
intelligence by reaction time.
°
°
Environment can influence protein synthesis as well; environment can contribute to the
degree of expression of genes. Environmental exposure at specific interval is critical (i.e. white-
crowned sparrow must hear adult song between 7
th
and 60
th
day or it will never sing that adult
song!!!) Environmental triggers (in critical periods) are important in gene expression.
°
°
Important to distinguish between genotype vs. phenotype:

Genotype: set of genes inherited

Phenotype: outward expression of genotype (characteristics, behaviours, etc.)
o
Dominant vs. recessive
 Outward characteristics may not indicate underlying genetic contribution.
 Homozygous (identical) vs. heterozygous alleles (not the same)
o
Homozygous alleles make genotypic predictions easy

o
Heterozygous involves finding dominant and recessive alleles

Codominance (i.e. sickle cell anemia)
°
° Polygenetic Effects : traits related to action of more than 1 gene or chromosome (more
than one gene codes for a trait)
Recombinant DNA procedures : using certain enzymes to cut long molecules of DNA into
pieces, combine them with DNA from other organism and insert them into host organism
Gene knockout procedure : deactivates one gene to observe effect on behaviour
o
Example: insert genetic material that will prevent neurons from transmitting
serotonin (knockout mechanism for serotonin reuptake), causing very anxious
behaviour
o
Problems: very few behaviours are controlled by on gene, disruption of gene may
affect a wide range of functions, and ethical considerations
°
Calculating heritability: H 2 = variance due to genes/ total variance
 Estimate of how much observed variability due to genetic alone
 H
2