Introduction

• • Neurons are the fundamental unit of the nervous system
• Neurons and glia are the main classes of cells we see in the NS
• Localized brain function


  theory proposed by Gall which stated that different parts of the brain had different functions
• what is aphasia

  language impairment
• Ramon y Cajal argued that the nervous system is made of discrete individual cells (neuron doctrine) rather than being a single continuous network (reticular theory)
• Mice are most commonly used in research because they are cheap and their brains are simple
• Members of a family are similar in traits because they are similar in genes. Similarity decreases as the percentage of shared genes decreases.
• Base pair sequence (aka the code of the gene)


  determines what the gene ends up doing
• Regulatory sequences


  regulate the expression of the gene (on/off)
• Coding sequences


  determine the structure of the gene's product
• the 4 key proteins in the nervous system are:

  Enzymes, receptors, transporters, and cytoskeletal parts
• Most traits are polygenic and traits that are monogenic tend to be disorders
• The total variability of the phenotype can be expressed as: 


  the sum of the variability due to genetics (VG) and the variability due to environment (VE):VP = VG + VE
• The heritability estimate ($h^2$) is the proportion of variability in a trait that is explained by genetics: $h^2=$$Vg/Vp$
• The higher the heritability estimate, the more likely it is that a trait is driven by genetic factors
• Heritability is a measure of how well differences in people's genes account for differences in their traits
• All traits are heritable (involve genes and are sensitive to genetic variation)
• A typical trait is associated with many genetic variants, with each accounting for a very small percentage of behavioural variability (< 1%) (one trait, many genes)
• Genes can serve many functions (one gene, many traits; termed pleiotropy)
• Epigenetics


  The study of meiotically or mitotically heritable changes in gene expression/function that cannot be explained by changes in DNA sequence