LAB 2: PowerLab 1: EEG, Psychophysiology and Wii Lab
when you are stressed, body signals adrenal medulla to release catacholamines
-epi/norepi -drive initial fight or flight response -also release cortiol: gluconeogensis, glucose mobilized, immune system depressed
wave frequency
-expressed in Hz (hertz) -the number of peaks in one second -a frequency of 1 Hz means that one peak occurs each second
The EEG during sleep: NON-REM
-four stages characterized by: -increase in sensory thresholds -increase is EEG wave amplitude -decrease in EEG wave frequency
The EEG and the functions of the cerebral hemispheres:
-left hemisphere- logical (reasoning, problem solving, language) -right hemisphere: creative (images, spatial processing)
beta waves: absent/reduced when?
-may be absent/reduced in areas of cortical damage -can be accentuated by sedative-hypnotic drugs
reading EMG:
-motor units fire asynchronously -as strength of muscle contraction increases, the density of action potentials increase -measured in milivolts (mV)
REM
-recurs every 90 minutes, with each REM period getting longer
delta waves: are seen where?
-seen during sleep (stages 3 and 4) and when the reticular activating system is damaged (anesthesia) -if awake and delta waves are seen= brain damage
alpha waves: when is it seen/abolished?
-seen when the eyes are closed and the subject relaxed -abolished by eye opening and by mental effort
gamma waves: seen/disappears?
-seen with higher mental activity (perception, consciousness) to form a coherent picture ex: Buddhist monks during meditation -disappears under general anesthesia ex: shizophrenia
NREM
-stage 1 and 2 -stage 3 and 4= slow wave sleep
NON-REM stages
-stage 1: decreasing beta and alpa, increasing theta -stage 2: irregular theta activity, increase in wave amplitude -sleep spindles (short bursts of waves) ***Stage 1 and 2 are light sleep
EEG signals are affected by:
-state of arousal of cerebral cortex -show changes in different stages of sleep -stimulation from the external environment
electromyography
-technique that measures electrical activity of skeletal muscles
brain waves generated by ____ ___, rather than by ___ ___
-the patterns of neuronal electrical activity recorded -generated by synaptic activity at the surface of the cortex, rather than by action potentials in the white matter
Eysenck's Cortical Arousal Model of Introversion and Extraversion
-there is some "optimal" level of electrical activity in the cortex -if we fall below this we tend to be bored and fall asleep, above this we are unable to deal with activity and feel overwhelmed -extraverts- need additional mental stimulation to reach this optimal cortical activity -intraverts- avoid additional stimulation as their cortical activity is already in the optimal region
what indicates onset of REM sleep?
-when alpha waves appear -the brain wave change is coupled with increases in heart rate, respiratory rate, and blood pressure; decreases in GI motility
clinical definition of consciousness- that grades behavior in response to stimuli as:
1. alertness - 2. drowsiness or lethargy (proceeds to sleep) 3. stupor (not asleep, but not in a coma) 4. coma (not sleep, LOC)
current suppositions about consciousness
1. it involves simultaneous activity of large areas of the cerebral cortex 2. it is superimposed on other types of neural activity (neurons are involved both in localized activities and in cognition) 3.it is holistic and interconnected (retrieval of a memory can be triggered by a smell)
two methods of recording an EMG:
1. needle electrodes inserted through the skin into the muscle 2. electrodes placed ont he skin surface
two main ways brain pays attention:
1. top down- willful, goal oriented (focus to read) 2. bottom up- reflexive attention to sensory info (loud noises, bright colors, threatening animals)
2 major types of sleep:
1.NREM (non-rapid eye movement) 2. REM (rapid eye movement)
why do we have REM sleep?
1.REM gives brain opportunity to analyze day's events 2. reverse learning- we dream to forget
which waves have the highest amplitude of any of the component EEG waves?
4. delta waves
EEG diagnose
Epilepsy, brain death, sleep disorders
although the eyes move rapidly under the lids during ____, most of the body's skeletal muscles are actively ____ and so ____
REM inhibited limp -temporary paralysis (prevents us from acting out our dreams)
what suppresses REM sleep, but not slow wave sleep?
alcohol and sleep meds (barbs)
highest state of consciousness and cortical activity
alertness
as with ECG, the EEG reflects the:
algebraic sum of the electrical potential changes occurring from large population of cells >>>therefore, large amplitude of waves requires the synchronous activity of a large number of neurons
we use the frontal lobe to know what we are doing within our environment (consciousness)-
how we initiate activity in response to our environment and judgments we make about what occurs in our daily activities
REM characteristics:
rapid, coordinated eye movements
beta waves: occurs when?
when we are mentally alert, with eyes open
cortical activity is ____ during sleep, but brain stem functions (respiration, heart rate, blood pressure, environmental ) ____
depressed continues
psychophysiology
-branch of science concerned with physiological bases of psychological processes -meases skin conductance (or electrodermal response-EDR), EMG, EOG, EEG, ERPs (event related potentials)
because spontaneous brain waves are always present (even during unconsciousness and come)- the absence of brain waves=
-clinical evidence of brain death -called a flat "EEG"
theta waves: common in/uncommon in?
-common in children; sleep at all ages -uncommon in awake adults
Non REM characteristics
-decreases in blood pressure, heart and respiratory rate -rolling, uncoordinated slow eye movements and passively decreased muscle tone
delta waves
-0.5-4 Hz; 100-200 uV -high amplitude
beta waves
-13 to 30 Hz; <20 uV -rhythmic, not as regular, higher frequenecy
in this lab, you will record EEG activity with 2 electrodes:
-2 frontal electrodes on the forehead -3rd (ground or earth) electrode attached to the mastoid process >>> to reduce electrical interference
sleep patterns: natural circadian rhythm
-24 hour rhythm -suprachiasmatic nucleus of hypothalamus- biological clock- regulates preoptic nucleus (sleep inducing center) -by inhibiting RAS (reticular activating system- maintains awake state)- cerebral cortex is put to sleep
gamma waves
-30-50 Hz
theta waves
-4 to 8 Hz; <30 uV -more irregular
Alpha brain wave
-8 to 13 Hz; avg amplitudes 30 to 50 uV -regular and rhythmic, low amplitude, synchronous wave
electroencephalogram
-EEG -records electrical activity of neurons -made by placing electrodes on the scalp and then connecting the electrodes to an apparatus that measures electrical potential differences between various cortical areas
origins of the EEG signals
-EEG results from slow changes in membrane potentials of cortical neurons ---> especially: EPSPs- excitatory postsynaptic potentials IPSPs- inhibitory postsynatpic potentials
NON_REM sleep: stages (continued)
-Stage 3- delta activity -stage 4- delta activity *** stage 3 and 4 in deep sleep
brain waves change with:
-age -sensory stimuli -brain disease -chemical state of body
EDR (Electrodermal response)
-also called GSR (galvanic skin response) -or SCL (skin conductance level) -eccrine sweat glands- respond to a person's mental state rather than due to an increase in temp. -act as variable resistors- skin resistance decreases and skin conductance increases (microsiemens-unit of conductance)
REM
-associated with dreaming -norepi, corticosteroids, testosterone secreted during REM (serotonin in NREM)
Why is EEG recording technically difficult?
-because of the small size of the voltage signals (50 uV peak to peak) essential: -Bio Amplifier built into Powerlab -use electrode of the right materia
we use ___ and ____ for vision reflexes and coordination of voluntary movement
brain stem and cerebellum
a state of unconsciousness from which a person CANNOT be aroused by even the most vigorous stimuli
coma
most depressed state of consciousness and cortical activity
coma
a sleeping person lacks something that he or she has when awake, we call this something-
consciousness
alpha waves: indicates degree of-
cortical activation- the greater the activation, the lower the alpha activity -alpha waves are strongest over the occipital cortex and frontal cortex
as we slip into deeper and deeper sleep, the frequency of the EEG waves ____, but their amplitude ___. blood pressure and heart rate also ____
decrease increase decrease
consciousness
encompasses conscious perception of sensations, voluntary initiation and control of movement, and capabilities associated with higher mental processing
The EEG and changes in intracranial metabolism
ex: hyperventilation -lowers blood PCO2---> results in hypocapnia (decreased PCO2) -thus cellular pH is high (acute respiratory alkalosis) -also blood vessels in brain constrict with reduction in brain blood flow ***causes slower rhythms and higher amplitudes
n general- the more active the brain, the ___ the frequency, and ____ the amplitude of the EEG.
higher, lower
amplitude or intensity of any wave is represented by:
how high the wave peaks rise and how low the troughs dip -reflects the synchronous activity of individual neurons
conversely: the more inactive the brain, the ____ the frequency, and the ___ the amplitude of the signal
lower, higher
what part of brain are we using when we concentrate on a task?
most of the brain
we use ___ lobe to deal with vision and our ability to locate objects in our environment and identify colors
occipital
just before we awaken, hypothalamic nuerons release:
orexins- "wake up" chemicals -as a result the sleepy cortex is awakened
what is used by the brain in tremendous amounts during REM?
oxygen -greater than during awake state
we use ___ lobe for location for visual attention as well as goal directed voluntary movements and manuipulation of objects
parietal
each brain wave is a continuous train of ___ and ___, and the wave ____.
peaks and troughs -frequency
artifacts
recordings may be spoiled by a range of unwanted interfering influences
defined as state of partial unconsciousness from which a person CAN be aroused by stimulation
sleep
why do we sleep?
slow wave sleep (NREM stages 3 and 4) is presumed to be restorative- the time when most neural activity can wind down to basal levels
we use ___ lobe for hearing ability, memory acquistion, and visual perceptions
temporal
the rhythmic events that the waves reflect often arise in the :
thalamus
Alpha waves: what do they indicate?
the brain is "idling"- a calm, relaxed state of wakefulness
EMG (electromyogram)
the data recorded
distraction
the divided attention of an individual from a particular task on to the source of the distraction -ex: texting while driving