(3) brain basics Flashcards
What is the difference between non-experimental and experimental methods?
Non-experimental:
- positive & negative correlation research
- no independent variable
- problem: 3rd variable
Experimental:
- independent variable affects change in dependent variable
- causality: covariation of cause & effect
- temporal precedence
- no plausible alternative explanation
What are the different types of variables?
- conceptual: resistant to direct measurements
- measured
- operational: directly measured
What is single blind?
participant doesn’t know
What is double blind?
participant & researcher don’t know
What is open label?
participant knows, due to ethical reasons
What are some basic features of the human brain?
- 2-3% of body weight
- uses disproportionately large amount: 15% of cardiac output, 20% of oxygen, 25% of glucose
- larger in men than women
- huge individual variation: no correlation w/ intelligence
- composed of neurons, glia, stem cells & blood vessels
- <100 billion neurons, more than half in cerebellum
- consistency of soft tofu
- convoluted (wrinkled): maximise cortex in skull (surface area)
- cells not replaced
What are the variety of brains observed in nature?
mammals, birds, reptiles
What about our brain’s basic features is most clearly related to our intelligence?
- disproportionately large compared to body weight
- more neurons/cubic cm
- intelligence correlates w/ sophistication of cellular connections
What are 2 types of cells in the nervous system?
- Neurons
- communicate quickly, targeted
- many types, but similar design
- dendrite (input) → soma (cell body) → axon (signal) → terminals (neurotransmitters released)
- communicate quickly, targeted
- Glial Cells
- scaffold for other cells
- support roles
- have receptors, transmitters
- shape conditions at synapse
What are the 2 sub-types of neurons?
- Projection neurons
- long axon
- project from 1 brain area to another
- Interneurons
- short axon
- project locally
What are the 4 sub-types of glial cells?
- Astrocytes
- blood-brain barrier
- provide nutrients to neurons
- maintain environment around neurons
- Microglia: detect bacterial cells
- prime state: active searching of brain
- Schwann cell: myelinate single axon in PNS
- Oligodendrocyte: myelinate several axons in CNS
What is the difference between white matter and grey matter?
- White matter: myelinated axons travelling from one place to another
- Grey matter: cell bodies/unmyelinated neurons
How can white & grey matter be visualised?
fMRI scans & staining:
- staining: take tissue & expose to dye, some cells absorb dye & some don’t
- Fibre stained → white matter
- Nissl-stained (cresyl violet) → grey matter
What are the divisions of the nervous systems?
SNS (sympathetic):
- afferent: carry sensory info from body to brain
- efferent: carry motor signals from brain to body
- have conscious access to info
ANS (autonomic):
- afferent: carry sensory info from organs to brain
- efferent: carry motor signals from brain to organs
- limited conscious access to info
What are the divisions of the brain?
Convolutions:
- gyrus/gyri: outward fold
- sulcus/sulci: inward fold
Nuclei: grey matter clusters under cortex
What are the divisions of the cortex?
Medulla
- if drug is potentially lethal w/ overdose, b/c of effects on medulla
- not functioning: affects heart & lungs
Hypothalamus
- controls variety of behaviours
- interaction area: b/w nervous & endocrine system
Limbic “system”
Nucleus accumbens (ventral striatum)
Why is locating a single region for a single behaviour often impossible? Explain using an example.
Controlling voluntary movement (e.g. drinking water):
- Prefrontal cortex: identify need & goals
- identify thirst & throat is dry, goals to satisfy need
- Premotor areas: turn intention into action, motor patterns
- Motor cortex: send signals to muscle groups, to perform movement
- Basal ganglia: learning habit, learning not to lift glass to fast & force to apply
- Pons: axons travel thru
- Cerebellum: sensory info from body, constant course correction, know where arm is, adjusting movement
What are the 3 structures that support the brain, their respective functions and how they relate to a course on drugs?
- Cerebral blood flow
- Blood-brain barrier (BBB)
- Skull & meninges
What is cerebral blood flow?
- limited supply
- 2 arteries in front: internal carolids
- 2 arteries in back: vertebrals
- brain gets blood from 4 arteries only
- no redundancy: artery damaged/lost - no arteries can replace it
- no reserves
- no energy store
- problem w/ blood flow, respiratory failure → brain tissue start dying in 3/4 mins
What is the blood-brain barrier?
Capillaries in brain:
- tightly packed:
- no space b/w cells
- astrocytes wrapped around
- protects brain
- active transport for large molecules
- drugs that cross BBB better work better
What is the skull & meninges?
- primarily protection for brain
Meninges:
- dura mater: outermost, thickest tough layer
- arachnoid mater/membrane: intermediate layer, not visible
- pia mater: thinnest layer
Ventricles & cerebrospinal fluid (CSF)
- support, protection, nutrition
- acting as an airbag
What is the central dogma of molecular biology?
Genes: sequences of DNA that control/partially control variable characteristics
- cell nucleus contains 46 chromosomes (made of DNA)
Polymorphisms: difference in genes, lead to differences in protein & protein’s function
Transcriptions: process of genes transcribing into mRNA then protein
Epigenetics: things that get passed on b/w generations, but not in DNA
- living w/ chronic stress
- affects DNA
Neurogenetics: studying genes related to nervous system development & function
What is a genetically modified organism? Why would such knowledge be beneficial in a class on drugs, brain, society?
Transgenic animals: has content not naturally in species
Knockout animals: removing gene & protein from animal
Conditional knockout mice:
1. raised normally
2. diet w/ special molecule: have thing that can be turned off/on based on chemical in diet
How is a pharmacology experiment designed? (1)
clinical drug study:
- independent variable - dose
- placebo as control, animals
- treatment arms: different levels/amounts of independent variable
- blinded procedures: single blind, double blind, open label
