Lecture3 Flashcards
What is involved with a contrast x ray?
A contrast substance is injected into the circulatory system to accentuate the difference between the target tissue & surrounding tissue
What does an x ray computed tomography (caT scan) do?; What can it detect?
Assists in reconstructing a 3-D structure of the brain from many individual slices; Small bleeds in the brain
What is the difference between a single slice & a helical caT scan?
Single slice: a thin slice (1-2 mm thick) is taken; Helical: x ray source continues to rotate so you get a continuous 3-D scan
What 2 methods can be used in Positron Emission Tomography (PET)?;
Either inject a radioactive isotope (2-deoxyglucose) into an artery or inhale C1502 (a radioactive isotope of C02);
What occurs in Positron Emission Tomography (PET)?; Radioactivity is…; The half-life of isotopes is…
After injecting or inhaling the isotope, a task is completed & then can measure which part of the brain is active. Isotope is taken up by active portions of the brain but is not broken down; Shortlived; Less than 3 hours
In the colour vs. grey study by Pearlman et al., which hemisphere showed activation in the colour condition?
Left hemisphere
In the motion vs. stationary study by Zihl et al., which hemisphere showed activation in the motion condition?
Right hemisphere
What does Magnetic Resonance Imaging (MRI) detect?
The waves emitted from hydrogen atoms when in a magnetic field
What is the purpose of Functional Magnetic Resonance Imaging (fMRI)?
It captures areas of increased oxygenated blood flow in the brain; more active areas take up more oxygenated blood which has magnetic properties
What does BOLD stand for?
Blood Oxygen Level Dependent signal
What are some advantages of fMRI?; What is a disadvantage?
No injection required; structural & functional information in the same image; good detail (spatial resolution); 3-D images of activity over the whole brain; Poor temporal resolution (takes 1-2 secs to travel from one area to another)
What occurs with the Paired Image Subtraction Method?
Control condition (no visual input) is subtracted from experimental condition (visual stimulation) & the difference is then detected so area is localised
What is involved with Transcranial Magnetic Stimulation (TMS)?; What’s an advantage of this method?
Single magnetic pulses are applied to specific locations on the scalp during a behavioural task or repetitively prior to task performance; magnetic activity disrupts activity in the targeted structures by inducing an electrical current; It permits causal inference about neccessities of specific brain regions for a given task
Which two methods are often paired together?; Why?
fMRI & TMS; Data from the fMRI scan is used to locate where to apply the TMS pulse
What does Magnetoencephalography (MEG) measure?; Temporal resolution is…; Spatial resolution is…
Changes in the magnetic fields on the surface of the scalp; generates magnetic field in orthogonal direction when action potential is fired; Very good; Poor
What does Electroencephalography (EEG) record?
Psychophysiological activity (electrodes); detects collective brain wave activity across a larger area
Why is it important to find the average of multiple responses in EEG as opposed to individual responses?
Individual signals are noisy, the average is more informative
What does Electromyography (EMG) record?
Muscle behaviour; it records neuronal spikes in response to a particular stimulus; takes negative values & makes them positive
What does Electrooculography (EOG) measure?
Activity in the ocular muscle; records where the eyes are moving
What does SCL stand for?; What does SCR stand for?
The baseline skin conductance level?; The skin conductance response - change in skin conductance in response to a stimulus
What does an Electrocardiogram (ECG) measure?
Cardiovascular activity
What does Stereotaxic surgery involve?; What type of research method is this?; Explain the process
The placement of a recording or stimulating device in a target of a region of the brain (typically used on rats); Invasive; Stereotaxic atlas locates the brain target, a hole is drilled then electrode is lowered & anchored to the skull with screws & dental acrylic that hardens around the electrode connector
What do Lesion methods involve?; Name the 3 permanent/irreversible types of this invasive procedure
Removing or disabling a portion of the brain & observing the resulting behaviour; Aspiration lesion, Radio frequency lesion & Knife cuts
What’s the difference between Aspiration Lesion, Radio frequency Lesion & Knife cuts?
Aspiration is like a vacuum, it selectively sucks up cell bodies & leaves axons in place; Radio frequency - device is implanted which emits intense radio frequencies in a particular area & destroys tissues around that region; Knife cuts are used to sever axons or nerve tracts, severs connections between nuclei
What is a Cryogenic Blockade?
A temporary lesion method, where a tiny cooling device is inserted into the brain & when it goes below a certain temperature the neuron will shut down
What are some of the negative effects of Lesions?
They are seldom administered with 100% accuracy; neighboring tissue may also be lesioned - functions are attributed to target tissue that are actually carried out by neighboring tissue; sometimes a portion & therefore some function remains but the structure may be discounted as playing a role in associated behaviour
Name 4 invasive Electrophysiological Recording Methods;
Intracellular unit recording, Extracellular unit recording, Multiple-unit recording, Invasive EEG recording;
What’s the difference between Intracellular & Extracellular unit recordings?; Temporal & Spatial resolution are…
Intracellular microelectrode records membrane potential from one neuron as it fires; Extracellular microelectrode records the electrical disturbance that is created each time an adjacent neuron fires; Very precise
What’s the difference between Multiple-unit recording & invasive EEG recording?
Mulitple-unit - a small electrode records the action potentials of many nearby neurons, they’re added up & plotted; EEG - a large implanted electrode picks up general changes in electrical brain activity (signal is not related to neural firing)
What is the goal of pharmacological methods?; What occurs?
To increase or decrease the effects of particular neurotransmitters; A cannula injects drugs to target tissue but they often don’t pass through the blood-brain barrier
How are Chemical Lesions administered?; How do they work?
Neurotoxic chemicals are injected into specific target tissue; Kainic acid destroys cell bodies close to the administration site but leaves axons unaffected; 6-hydroxydomamine is taken up only by neurons that release norepinephrine or dopamine, leaving other cells unaffected
Which technique measures chemical activity in the brain?; What is involved?
2-Deoxyglucose Technique (2-DG), similar to glucose but not rapidly metabolised by neurons (stays in the cells); It’s taken up by active neurons, after engaging in target behaviour the animal is sacrificed & its brain sliced, regions with high concentration of 2-DG are identified on photographic film as responsible for the behaviour
Apart from 2-DG, what’s another way of locating neurotransmitters in the brain?; What is involved?
Immunocytochemistry; Injecting labelled antibodies that bind to enzymes in neurons responsible for producing the target transmitter, animal is sacrificed & brain sliced, clusters of radioactive marker indicate the location of neurotransmitter production
How are concordance & discordance rates for various disorders compared in Genetic Methods?
If a monozygotic (identical twins) sample has a higher concordance rate than a dizygotic sample it is evidence for heritability
What evidence suggests that schizophrenia is a heritable trait?
Concordance rates in monozygotic twins is 4 times higher than in dizygotic twins
In genetic engineering, what do Gene Knockout techniques involve?; What are the problems with this method?
Knocking out a specific gene & observing the behavioural consequence; Behaviour is often the result of actions & interactions of several genes, elimination of 1 gene often influences the expression of other genes & environmental determinants
In biopsychology behavioural research methods, what 2 stages are generally involved in neuropsychological testing?
A battery of general tests & a follow up of more specific tests guided by the first tests (typically for stroke or head injury patients)
What do general tests in neuropsychological testing include?
IQ tests with memory & language subtests; a token test of language ability; relationship between different shapes or patterns, etc
What does a Sodium Amytal Test identify?; How?
Language lateralisation (responsible hemisphere); Anaesthetic is injected into the left or right carotid artery (eg. left will shut down verbal ability)
If a memory impairment is detected in the general test battery, which 4 questions about the impairment need to be answered?
Is it short-term or long-term memory or both?; are the deficits anterograde or retrograde or both?; semantic or episodic memory or both?; explicit or implicit long-term memory?
What difficulties do patients with frontal lobe damage have in the card sorting task?
Adapting to the change of rules
What are the 3 main categories of studying common animal behaviour?
Open field test (aggressive/defensive/sexual behaviour); conditioning paradigms; semi-natural animal learning paradigms (food aversion conditioning, radial arm maze & water maze)
How soon can conditioning occur with food aversion conditioning?; What doesn’t apply to this conditioning?
After just one trial, even though the consequence (getting sick) is delayed by several hours; Equipotentiality - taste is primary
In regards to spatial awareness, how do mice locate food placed in a radial arm maze? If you rotate it?
They learn the layout quickly if reinforced with respect to whole global environment; They continue in the same direction relative to the room
What gives more weight to evidence about responsibilities of brain structures on given behaviours?
Consistent results from several of these tests to provide converging evidence
