what is a computerised tomography (CT) scan?
- X-ray beam projected through head to an X-ray detector (from all angles)
- makes a series of pictures of skull and brain
pros and cons of CT scan?
relatively cheap and fast, but resolution is not great for soft tissue like brain
what is magnetic resonance imaging (MRI)?
- strong magnetic field and low energy radio waves
- large cylinder, strong magnetic field applied, magnet causes hydrogen p+ to spin in particular direction (in line with magnetic field)
- p+ spins and emits radio wave
- see relative density of hydrogen atoms in body
what can MRI do?
identify the density of water molecules and fat molecules, providing high resolution, 3D image of brain
what is diffusion tensor imaging (DTI)?
type of MRI technique
- MRI made more sensitive to water molecules than lipid molecules
- identify where water molecules are moving
- measures direction and speed of water molecules
- creates images that show the location and direction of every axon
what is functional magnetic resonance imaging (fMRI)?
- used rapid series of MRI scans that reveal movement of oxygenated blood during brain activity
pros of fMRI?
- doesn’t involve needles, surgery, or radioactivity
- provides structural and functional information with decent spatial resolution and temporal resolution
what is positron emission tomography (PET) scan?
- inject person with radioactive sugar to detect changes in energy in brain
- measure changes in expression levels of NT receptors
pros and cons of PET scan?
pros: glucose is taken up by body and not broken down as easily as sugar so stays around for hours
cons: expensive, radioactive molecules have to be made on site the morning of experiment
are there fewer or more dopamine neurons in the brains of people with Parkinson’s?
fewer dopamine neurons
what is an electroencephalogram (EEG)?
- measure of electrical activity in the brain that uses macroelectrodes (metal discs) attached to the scalp
- records summed activity of millions of neurons
- associated with different stages of consciousness, sleep, and cerebral atrophy
what is experimental ablation? what does it do?
lesion study that involves removal or destruction of portion of brain (functions no longer performed following surgery controlled by that region)
what are radiofrequency lesions? what is a downside?
- small lesions made by passing radiofrequency current through a metal wire that is insulated everywhere but the tip
- electric current produces heat that burns cells around tip of wire
- size and shape of lesion determine by duration and intensity of current
- axons just passing through will also be burned
what is an excitotoxic lesion? do they affect passing through axons?
brain lesion technique that is selective for cell bodies
- microinjections of glutamate receptor agonist which causes neurons to spike so much they undergo apoptosis
- no receptors on axons so they don’t affect while passing through
what is a sham lesion?
“placebo” procedure that duplicates all steps of producing a brain lesion except for the step that causes extensive brain damage
what is a reversible lesion?
caused by injecting drugs that temporarily inhibit neuronal spiking
- drugs: voltage-gated sodium channel blockers (stops AP), GABA receptor agonists (hyperpolarize cell bodies)
what is chemical stimulation? are axons passing through affected?
- infusion anesthetics shut down neural activity and stop AP
- infusion of receptor agonists or antagonists selectively affect cell bodies and synapses (no NT receptors on axons)
- axons passing through are not directly affected by drug infusions
to infuse a drug into a specific brain region prior to behavioural test, you must do what?
first plant metal straw in brain area
then chemical stimulation
what is electrical stimulation? does it affect axons passing through?
- delivering electrical current through an implanted metal wire will stimulate everything in the area (cell bodies and axons passing through)
how does low frequency stimulation affect spiking activity? what about fast?
slow = increases spiking activity
faster (more than 100x/s) = produce same effects as lesioning
what are microelectrodes? what are they used for?
- thin metal wires with a fine tip that can record the electrical activity of individual neurons (single-unit recordings)
- used during behavioural tests to record every AP from a given neuron
- implanted in brains of animals during stereotaxic surgery
what are chronic recordings? what are acute recordings?
chronic = recordings made over extended period of time
acute = recordings made over short period of time (immediately after implantation while animal is anesthetized)
what is optogenetics?
use of light to control neurons that have been made sensitive to light through the introduction of foreign DNA (provides instructions to make light-sensitive proteins opsins)
where are tons of different types of light-gated ion channels evolved from?
bacteria and algae
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lecture 1, 2, 319
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lecture 4 - synaptic communication23
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lecture 5 - neurotransmitters34
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lecture 6 - drugs27
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lecture 7 - brain anatomy68
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lecture 8 - research methods31
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lecture 9 - vision 177
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lecture 10 - vision II57
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lecture 11 - hearing and vestibular systems70
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lecture 12 - touch, taste, smell49
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lecture 13 - hunger and thirst53
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lecture 14 - sex40
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lecture 15 - sleep49
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lecture 16 - learning and memory27
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lecture 17 - types of learning and memory74
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lecture 18 - language50
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lecture 19 - emotions37
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lecture 20 - genetic predispositions39
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lecture 21 - schizophrenia and autism46
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lecture 22 - neurological problems48
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lecture 23 - mood disorders & neurodegenerative disease78
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lecture 24 - Stress, Anxiety, OCD, Addiction, ADHD59
