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