SLEEP AND EEG

DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
SLEEP AND
ELECTROENCEPHA
LOGRAM

OBJECTIVES.
 Electrical activity of the brain.
 Evolked cortical potential
 Electroencephalogram
 Wakefullness and sleep.
 Wakefullness
 Neural substrate
 Chemical mediators.
 Sleep

ELECTRICAL ACTIVITY OF THE
BRAIN.
 Evolked cortical
potential.
 Primary Evolked
potential.
 Diffuse secondary
response.
Wednesday, April 25, 2018

EVOLKED CORTICAL
POTENTIAL.
 Surface electrical
activity recorded from
scalp in response to
specific & adequate
stimulus.
 Electrical activity of
2 types.

PRIMARY EVOLKED
POTENTIAL.
 Initial brief & localized
response over the
specific sensory cortex.
 Characterized by
 Latency – 5-12 ms
 Surface positive followed
by negative wave.
 Highly specific in its
location.

DIFFUSE SECONDARY
RESPONSE.
 Latency – 20-80 ms
 Positive negative wave
sequence larger & more
prolonged.
 Not highly localized.

TYPES OF EVOLKED
POTENTIAL.
 Depending on type of
stimulus.
 Visual Evolked potential.
(VEP)
 Brain stem auditory
Evolked potential
(BAEP)
 Somatosensory Evolked
potential.
 Event related
potentials.

TYPES OF EVOLKED
POTENTIAL.
 Depending on
latency of
response.
 Stimulus related
potentials.
 Event related
Evolked potential.

STIMULUS RELATED
POTENTIALS.
 Series of waves relates to
sensory modality.
 Early latency response –
latency < 10ms
 Mid-latency response –
Latency 10-50 ms.
 Long latency response –
latency > 50 ms.

EVENT RELATED EVOLKED
POTENTIAL.
 Dependent on subject’s
attention & level of
arousal.
 Related to cognitive
events associated with
distinction of target
from non- target
stimuli.

CLINICAL USES OF EVOLKED
POTENTIALS.
 Stimulus related Evolked potential – Reflects
functional integrity of sensory pathway.
 So any defect is shown by delayed peak or Interpeak
latencies.
 Event related Evolked potential.
 Related to cognitive behavior.
 By use of ERP clinical assessment of Dementia &
Delirium is well established.

ELECTROENCEPHALOGRAM
 Introduced by German
Psychiatrists Hans
Berger.
 Record of spontaneous
electrical activity of
brain taken from
surface of scalp.

ELECTROENCEPHALOGRAM
 The wave oscillations differ
in frequency & amplitude
in different points on scalp
& during mental alertness.
 Frequency – range 1-50
cycles/sec.
 Amplitude – 50-200 μV.
 Irregular & without any
pattern.

WAVES OF EEG
 Alpha waves
 Beta waves.
 Theta waves.
 Delta waves.

ALPHA WAVES
 Most prominent
 Person awake, quiet at rest
, eyes closed.
 Characteristic features.
 Frequency – 8-13 Hz.
 Amplitude – 50 μV.
 Location – Parito-occipital
area.
 Disappear – During sleep.

ALPHA WAVES
 Causes of decreased
frequency.
 Old age, decreased
cerebral metabolism
 Low BSL
 Low body temp
 Low adrenal
Glucocorticoids.
 High arterial Pco2
 Sleep.
 Causes of increased
frequency.
 Alpha block – α waves
attenuates & replaced by
fast ,irregular & low
amplitude waves. Occurs in
 Open eyes
 During conscious mental
activities.
 During aroused & alerting
response.

BETA WAVES.
 CHARACTERISTIC
FEATURES.
 Location – Parietal &
frontal area.
 Appear – Tension & CNS
activation.
 Arousal response
 Infants & Barbiturates.

THETA WAVES.
 CHARACTERISTIC
FEATURES.
 Amplitude – 10 μV.
 Location – Temporal &
Parietal region in children.

THETA WAVES.
 Do not in normal waking
individuals (except in
Newborn)
 Seen in emotional states
like Disappointment &
Frustration.
 Many brain disorders.
 Increased during crying
in children.

DELTA WAVES.
 CHARACTERISTIC
FEATURES.
 Frequency – < 4 Hz.
 Location – Strictly in
cortex.

DELTA WAVES.
 CHARACTERISTIC
FEATURES.
 Do not occur in normal
waking individuals but
seen in
 Deep sleep (stage III &
IV of NREM)
 Infancy
 Serious brain damage.

NEUROPHYSIOLOGICAL BASIS
OF EEG.
 Cortical Grey matter along with its thalamic
connections are mainly responsible for Rhythmic
discharge of cells & EEG.
 Current flow in the fluctuating dipoles.
 Dendrites are sites of polarizing & Hyperpolarizing
local potential change.

NEUROPHYSIOLOGICAL BASIS
OF EEG.
 So cell dendrite relationship is constantly shifting
dipole.
 So becomes sites of current sink.
 EEG is due to Graded potentials which are post
synaptic potentials in Brain neurons.

SYNCHRONIZING
MECHANISMS.
 Rhythmic discharge from thalamus.
 Synchronizing activity of neighboring cells due to
 Effect of parietal neural process to each other.
 Interconnections of neurons by Inhibitory pathway.

DESYNCHRONIZING
MECHANISMS.
 α block – replacement
of rhythmic EEG pattern
with irregular low
voltage activity.
 Due to sensory
stimulation of RAS.

VARIATION IN EEG WAVE
FORMATION WITH AGE.
 In Infants – occipital
rhythm is slow(0.5 Hz)
than Adults (8-13 Hz).
 In children occipital
rhythm speeds up & adult α
pattern gradually appears
in adolescence.
 After 15 years EEG
waveforms become same
as adults.

ABNORMAL EEG WAVEFORMS
 1 Epilepsy.
 Idiopathic abnormal
waves as spike, sharp
wave & spike & slow
wave complex.
 Between abnormal
irregular slow wave
appears.

TYPES.
 GRANDMAL EPILEPSY
– Serious fits
accompanied by
convulsions with tonic
muscle contraction,
clonic jerks & loss of
consciousness.
 EEG shows continuous
spike or sharp waves.

TYPES
 PETITMAL EPILEPSY –
Sudden loss of consciousness
for few sec without
convulsions with local
twitching.
 PSYCHOMOTOR EPILEPSY –
Typical fit with inappropriate
movements with
hallucinations without loss of
consciousness.

 2 Consciousness Dysfunction – slow wave
appears.
 Disturbance of consciousness in coma, stupor &
syncope.

 3 Organic brain Dysfunction – when brain
functional trouble occurs – no wave is generated
from that part but slow wave is generated from
surrounding organization.

 4 Brain Death –
Individual delclared
dead when brain cells
stop activity, EEG waves
becomes flat in all
channels & finally
disappears.

WAKEFULLNESS
 The RAS of Reticular
formation is the neural
substrate of the
consciousness & sleep
waking cycle.

NEURAL SUBSTRATE FOR
WAKEFULLNESS.
 Reticular activating system. – Responsible for
tonic maintenance of cortical activation &
Behavioural arousal of wake fullness.
 Thalamus – VM, Intra-laminar & Midline nuclei are
involved in activation of entire cerebral cortex.

NEURAL SUBSTRATE FOR
WAKEFULLNESS.
 Hypothalamus and
sub thalamus.
 Basal forebrain –
Mainly Nucleus Basalis
of Meynert, Nuclei of
Diagonal band &
septum.
 It receives impulses from
Reticular formation.

CHEMICAL MEDIATORS OF
WAKEFULLNESS
 Neurotransmitters.
 Cerebrospinal fluid
borne peptides.
 Blood borne
peptides.

NEUROTRANSMITTERS.
 Catecholamines – NE neurons of locus Coeruleus &
Brain stem project diffusly to forebrain & cortex
play an imp role
 Acetylcholine - – Cholinergic agonists &
anticholinesterase promote cortical activation &
wakefulness.

NEUROTRANSMITTERS.
 Histamine – Arousing effect produced by
intraventricular administration of Histamine
 Sedative effect produced by Antihistaminics.
 Glutamate- Excitatory Neurotransmitters released
from cerebral cortex in highest quantities in cortical
activation.

CEREBROSPINAL FLUID
BORNE PEPTIDES.
 Substance P
 Hypothalamic
releasing factors.
 Vasoactive intestinal
peptides.

BLOOD BORNE PEPTIDES.
 Epinephrine &
histamine – Do not cross
BBB but act on
circumventricular organ.
 Glucocorticoids – these
readily cross BBB.

SLEEP
 State of
Unconsciousness from
which person can be
aroused by sensory or
other stimuli.

SLEEP WAKE CYCLE AND
FACTORS AFFECTING SLEEP.
 Control of sleep wake cycle.
 Sleep wake cycle –
endogenous
 Biological clock – in
Suprachiasmatic Nucleus of
Anterior Hypothalamus.
 Zeitgebers – Time givers;
Most imp is sunlight
through
Retinohypothalamic tract.

FACTORS AFFECTING SLEEP.
 Darkened room
 Comfortable surrounding
temperature
 Silence
 Physical & mental
relaxation.
 Consumption of basic urge
 Low frequency stimulation.

TYPES AND STAGES OF SLEEP
 Non-REM sleep.
 REM SLEEP.
ALTERNATE IN A
SLEEP CYCLE.

TYPES AND STAGES OF SLEEP
 Non-REM sleep – Non
rapid eye movement
sleep (slow wave
sleep)
 Sleep begins with
Non-REM.

STAGES AND EEG PATTERN OF
NON-REM SLEEP.
 Stage of wakefulness –
state of wakefulness &
consciousness due to RAS
stimulation to cortex.
 EEG – Low amplitude β
waves.
 Stage of quiet, awake rest
with eyes closed.
 Highly synchronized large α
waves

STAGE OF NON-REM SLEEP.
 Stage 1 – low amplitude
mix frequency activity.
 Stage 2 – Stage of light
sleep, sleep spindles
appears.
 These are bursts of α
like 10-14 Hz, 50 μv
waves.

STAGE OF NON-REM SLEEP.
 Stage 3 – Stage of
Moderate deep sleep
 High amplitude slow
waves i.e. δ waves
 Stage 4 – Deep sleep
 Dome like very slow,
large waves called δ
waves
 Characterized by Marked
synchronization.

PHYSIOLOGICAL CHANGES
DURING NON-REM SLEEP
 Muscle tone
 Heart rate & BP
 Respiratory rate
 Body metabolism
 Eyes – slow rolling movements
until finally stop in stage 4 with
eyes turned upwards.
 Pituitary pulsatile release of
growth hormones & Gonadotropins
– slows down.

BEHAVIORAL CHANGES
 Consciousness – progressively reduced.
 Resistance to be awakened increases.
 When awake do not report Dreaming.
 Discriminate response to meaningful & non
meaningful stimuli.

INTELLECTUAL FUNCTIONS
DURING NON-REM SLEEP.
 Thoughts becomes
illogical & Incoherent
towards sleep.
 Retrograde Amnesia.
 Sleep inactivates
consolidation of short
term to long term
memory

REM SLEEP
 RAPID EYE
MOVEMENT SLEEP /
FAST WAVE SLEEP /
Paradoxical sleep /
Deepest sleep /
Dream sleep.

EEG PATTERN OF REM SLEEP.
 High frequency low
amplitude pattern ( β
rhythm)
 So also called
Desynchronized or fast
wave sleep.
 More difficult to awake in
REM than Non-REM
 EEG Pattern of Wakefulness
- Paradoxical

PHYSIOLOGICAL CHANGES
 Rapid Eye Movement
 HR & RR – Irregular.
 Muscle tone – reduced.
 Twitching of limb.
 Middle ear muscles active
 Penile erection in males & Engorgement of Clitoris in
females.
 Impaired Thermoregulation
 Teeth Grinding.

BEHAVIORAL CHANGES
DURING REM SLEEP
 Arousal –
 Difficult to arouse
 But when awakened
immediately alert &
aware
 Dreaming occurs
 80% - vivid dreams
recall.

SLEEP CYCLE.
 Average sleep period of
7-8 hr divided into 5
cycles of Non-REM &
REM, alternate with
each other.

SLEEP CYCLE.
 Duration of sleep cycles and sleep stages.
 Avg duration of each cycle – 90 min.
 In 1st
cycle 85 min is NREM & 5 min REM.
 25% of entire sleep is in REM.
 NREM decreases & REM increases in further cycles.

VARIATIONS IN SLEEP CYCLES.
 In adult sleep starts with REM in special
conditions as
 Jet lag, Chronic sleep deprivation, narcolepsy, acute
withdrawal of REM suppressing drugs, endogenous
depressions.

VARIATIONS IN TOTAL SLEEP
DURATIONS.
 Avg sleep time per day
 Infant – 16hrs.
 Childhood -10 hrs
 Adulthood -7-8 hrs.
 Old age - < 8 hrs.

VARIATIONS IN TIME PERIOD OF
DIFFERENT STAGES OF SLEEP.
 Effect of AGE.
 Premature infant – 80% in REM
 Full term infant – 50 % in REM.
 In adulthood reduction in total sleep time to 8 hrs.(2
REM; 6 NREM)

GENESIS OF SLEEP
 Genesis of Non-REM sleep.
 Genesis of REM sleep.

GENESIS OF NON-REM SLEEP.
 Diencephalic sleep zone
 Sleep fascilitatory center – Ant Hypothalamus.
 Sleep inhibitory center – Post Hypothalamus.
 Medullary synchronizing zone
 Basal forebrain sleep zone.

ACTIVITY OF NON-REM ON
CELLS
 Mechanism of production of sleep spindles and
slow waves of Non-REM sleep.
 These synchronized synaptic potentials are rhythmic
firing of thalamic relay neurons to cortex.
 This rhythmic firing is due to GABAergic inhibitory
neurons in Nucleus Reticularis around thalamus.

GENESIS OF REM SLEEP.
 Role of cholinergic neurons of Mid-brain and the
adjacent dorsal Pons.
 Role of Nucleus Reticularis pontis oralis.
 Cholinergic PGO on cells.
 REM waking on cells.
 REM on cells.

CHEMICAL MEDIATORS OF
SLEEP
 Neurotransmitters – Include Serotonin,
Acetylcholine & Noradrenaline.
 Sleep producing substances are – Muramyl
Dipeptide (found in bacterial cell wall), Interleukin-
1, adenosine, Delta sleep inducing peptide, PGD2,
Argenine vasotoxin.

PHYSIOLOGICAL SIGNIFICANCE
OF SLEEP.
 Sleep may serve as a period of body’s rest and
metabolic restoration.
 Sleep is necessary for certain forms of learning.

PHYSIOLOGICAL SIGNIFICANCE
OF SLEEP.
 REM sleep is necessary for mental wellbeing.
 REM sleep plays an important role in homeostatic
mechanism.

SLEEP DISORDERS.
 Insomnia.
 Fatal familial
insomnia.
 Narcolepsy.
 Some sleep
disorders associated
with non-REM sleep
(slow wave sleep)

SLEEP AND EEG

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to SLEEP AND EEG

Similar to SLEEP AND EEG (20)

More from Dr Nilesh Kate

More from Dr Nilesh Kate (20)

Recently uploaded

Recently uploaded (20)

SLEEP AND EEG