Biopsych Flashcards
Sperry
- natural experiment
- 11 ppts with a severed corpus callosum due to epilepsy
- images flashed onto left and right visual fields for 1/10 of a second and ppts asked to name / describe / draw objects
- also, objects placed in either left or right hand behind a screen
findings
- info shown in right visual field could be described in speech and writing, if presented to left visual field, ppts could neither remember nor describe the object
- objects placed in right hand could be described in speech and writing, if placed in left, ppts guessed and some were unaware of the object
Maguire et al
- MRI scanned London taxi drivers’ brains and calculated amount of grey matter
- when compared to control group, drivers had significantly larger posterior hippocampi
- size was also positively correlated with time spent driving
MRI
- magnetic resonance imaging
- magnetic field causes hydrogen atoms in body to move, and return to original positions when turned off
- tissues of different densities give off different signals, which is interpreted by a computer
FMRIs
Functional magnetic resonance imaging
- uses radio waves and magnetic fields to detect changes in oxygen levels in the blood
+ good spatial resolution - can detect differences in different areas of the brain
- poor temporal resolution - cannot detect differences over time
- high running cost
EEGs
Electro-en-ce-pha-lograms
- electrodes placed on scalp to record brain activity
- wave patterns generated
- often used in sleep studies
+ high temporal resolution
- poor spatial resolution
ERPs
Event-related potential
- electrical activity due to stimuli
- EEG + stimulus
Infradian rhythms
- over 24 hours
- e.g. menstrual cycle
ultradian rhythms
- more than once over 24 hours
- e.g. sleep stages (deep sleep / REM)
circadian rhythm
- around 24 hours long
- sleep-wake cycle
endogenous pacemakers
- internal signals
endogenous pacemaker for sleep wake cycle
- suprachiasmatic nucleus (SCN)
- part of hypothalamus
exogenous zeitgeber
external signal
exogenous zeitgebers for sleep examples
- light
- alarm clocks
- bird noises
menaker et al
- bred hamsters to have abnormal circadian rhythms of 20 hours
- SCN was then transplanted into normal hamsters
- normal hamsters showed same abnormal rhythms
- and reverse - when regular SCN was put into abnormal hamsters, their circadian rhythms corrected
siffre et al
- case study
- lived in a cave with no clocks, radio or daylight
- after 60 days, his circadian rhythm changed to 26 hours
process of sleep
- darkness
- optical chiasm
- stimulates SCN
- stimulates pineal gland
- melatonin production
- enhanced serotonin production
- brain activity falls
- sleep
