Chapter 5 - Research methods of biopsychology Flashcards
How do X-ray based techniques work?
- when an x-ray is taken, an x-ray beam is passed through an object onto a photographic plate.
- each of the molecule through which the beam passes absorbs some of the radiation
- only the unabsorbed portions of the beam reach the photographic plate
What are contrast x-rays used for and how do they work?
- can be used to visualize the brain
- they involve injecting a subtstance that absorbs x-rays either less or more than the surrounding tissue
hence, something is contrasted :)
Cerebral angiography
- one contrast x-ray technique
- uses the infusion of the radiopaque dye into a cerebral artery to visualize the cerebral circulatory system
- for locating vascular damage.
- displacement of blood vessels
What is computed tomography?
- computer assisted x-ray procedure
- used to visualize the brain
- and other internal structures of the body
Positron Emission tomograpgy (PET)
- provides images of the brain activity rather than the structures
- FDG (radioactive) is injected and taken up by active cells - most active areas indicated
- PET scan is an active image of the levels of radioactivity
Radioactive fluorodexyglucose (FDG) is injected … (PET technique)
- FDG is taken up by active cells (can’t be metabolized) - accumulates in neurons
- the PET scan indicates the area most active
Magnetic Resonance imaging (MRI)
- structural brain-imaging procedure
- high resolution images are constructed from measurement of radiofrequency
- high spatial solution, 3D images
functional MRI (fMRI)
- produces images representing the increase in oxygen flow in the blood to active areas in the brain
- BOLD signals (blood oxyygenated level dependent signal)
- oxygenated blood accumulates in active areas
fMRI is possible because of two attributes of oxygenated blood
- active areas take up more oxygenated blood than they need for their energy requirements
- oxygenated blood has magnetic properties that influence the radio-frequency waves
What are four advantages of MRI over PET?
- nothing has to be injected
- provides structural and functional info in the same image
- spatial resultion is higher
- produces 3D images
Diffusion tensor imaging
- variation of MRI
- method of identifying pathways along which water molecules rapdily diffuse
- provide an image of major tracts (bundles of axons)
Transcranial magnetic stimulation (TMS)
- technique that can be used to turn off an area of the human cortex by creating a magnetic field under a coil positioned next to the skull (also turn on)
- play a role in establishing the causal effects of human cortical activity on cognition and behavior.
Transcranial direct current stimulation (tDCS)
can be used to stimulate (turn on) an are of the cortex by applying an electrical current through two electrodes placed on the scalp.
Electroencephalogram (EEG) - what does this measure?
is a measure of gross electrical acitvity of the brain - by encephalogram machine
Electroencephalogram (EEG) - How does this work?
- each channel of EEG activity is usually recorded from disk-shaped electrodes
- reflects the sum of electrical events throughout the head.
- events include action potentials, postsynaptic potentials and electrical signals from skin etc.
Event-related potential (ERPs)
the accompaying EEG waves
Sensory evoked potentials
(and and EEG that follows a sensory stimulus has which two components?)
- one commonly studied type of ERP (event-related potetnial)
- the change in the cortical EEG signal elicited by the momentary presentation of a sensory stimulus.
Two components:
1. The signal (the response to the stimulus)
2. The noise (the ongoing background EEG activity)
Signal avering
reducing the noise of the background EEG, which is canceled out by averaging.
Magnetoencephalography (MEG)
measures changes in the magnetic field on the surface of the scalp that are produced by underlying patterns of neural acitvity.
What are different psychphysiological measures of SNS (somatic nervous system) activity?
- Electromyography (EMG)
- Electrooculography (EOG)
What are different psychophysiological measures of ANS (autonomic nervous system) activity?
Skin conductance:
- skin conductance level (SCL)
- skin conductance response (SKR)
Cardiovascular activity:
- heart rate
- blood pressure
- blood volume
Electromyography (EMG)
used to measure muscle tension
- usually recorded between two electrodes taped to the surface of the skin over the muscle of interest
Electrooculagraphy (EOG)
- when the eye moves, a change in the electrical potential between electrodes placed around the eye can be recorded
- based on the fact that a steady potential difference exists between the front (positive) and the back (negative) of the eyeball
skin conductance level (SCL)
a measure of the background level of skin conductance that is associated with a particular situation
skin conductance response (SCR)
measures the transient changes in skin conductance that are associated with discrete experiences.
What are three different measures of the cardiovascular acitvity?
- Heart rate
- Blood pressure
- Blood volume
Systoles (blood pressure)
peak pressure during periods of heart contraction
Diastoles (blood pressure)
measurment of the minimim pressure during the periods of relaxation.
Plethysmography
various techniques for measuring changes in the blood volume.
What is the stereotaxic surgery?
means by which experimental devices are precisely positioned in the depths of the brain
stereotaxis atlas
used to locate brain structures, series of individual maps
(stereotaxic surgery)
bregma
point on top of the skull where two major sutures intersect
(stereotaxic surgery)