Electroencephalogram,
Spindles and K complexes
Sleep
• The default state
• Active Process
• Requires synchronizers

• Sleep Spindles, K Complexes
Raphe promotes sleep
Locus coeruleus
promotes
wakefulness

*so sleep control
is distributed
across centers
The reticular formation also
promotes wakefulness
Stages of sleep form cyclical pattern

Slow-Wave Activity:
-- Spindles:
7 - 15 Hz ; Wax and
Wane
-- Delta:
1 - 4 Hz
-- Slo...
Sleep Spindles
• Compared to alpha rhythm !!
• One of the earliest described events
• Hallmark of Synchronization

• Requi...
Midpontine pre- trigeminal
Cerebellum

Encephale isole‘

Klimesch VO: BioIII

Normal sleep-wake cycle including REM

Cerve...
THALAMUS
Gyri orbitales

Gyri frontales

Co
rp
u

G. praecentralis
G. postcentralis
RE
Gyri
temporales

VA
VL
VP LP
Pu

LGN
MGN

Gy...
Thalamocortical
Network
Ctx
+
+
RE

+

TC
-
Thalamocortical spindle circuitry

Modified from Steriade and Llinás. Physiol.Rev. 68:649-742, 1998.
T type calcium channel genes in
thalamus

α1G

α1H

α1I
Courtesy of E Talley, D Bayliss & E
Perez-Reyes
Post inhibitory rebound in thalamic
relay neurons

-60

Vm

-70
-80

Ca2+depende
nt
rebound
burst

IPSP

threshold

1

hT
...
Thalamo-cortical reentrant loops.
Steriade, M. (1999). Coherent oscillations and
short-term plasticity in corticothalamic ...
1,2

Afferent brainstem input to Th-cx (1),
Activation of RE and Cortex (2)
Cortex

L-circ
RE

Th-cx

Dendro-dendr.

Th-cx...
3 Excitatory processes in Cortex;
Inhibition of primary L-circ;
Inhibition of other RE cells

Cortex

L-circ
RE

Th-cx

De...
4

Excitatory feedback response from cortex.
Disinhibition of primary L-circ neurons.
Inhibition of secondary Th-cx neuron...
5 The primary Th-cx cell may start a new excitatory burst into the cortex. At this stage
(because released from the L-circ...
Summary of findings:
Afferent brainstem activation is missing and cortical activation is strong:
- Th-cx cells are hyperpo...
Spindle oscillations in thalamus
A M P A /N M D A R

T h a la m u s

G A B A AR

nR t
T C

+
timing
R ebound
B u rs t
E P ...
RE Cell Rapidly bursting type
A Mathematical model

Foundations II - Neuroimaging
TC Cell modulation by RE cell
A Mathematical model
Propagation of Spindles
Ontogeny of Spindles
• EEG maturation
• Posterior Dominant
• Anterior spread
• Amplitude decreases with age
• Two ditinct ...
K Complexes
Paroxysmal Events
K Complexes
• stage 2 sleep, arousing stimuli.
• Loomis et al. (1938);
• reason for calling them K complexes
remains obscu...
• H. Davis et al. - central and frontal K
complexes
• Brazier (1949) presumed two distinct
generators; these were area 6,
...
Positive occipital sharp transients of sleep

POSTS start to occur in healthy people at age 4 years, become fairly common
...
Vertex sharp transients

Also called vertex waves or V waves, these transients are almost
universal. Although they often a...
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
Spindles and transients - Sleep Phenomena, Mechanisms and Substrates
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Spindles and transients - Sleep Phenomena, Mechanisms and Substrates

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This presentation discusses in detail the transients that occur mainly in late stage 1 and stage 2 of sleep, and may be confused to be pathological. The prototype here are theK complexes and the Sleep Spindles.

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  • Incomplete synchrony, sparseness, also seen in vitro, higher synchrony seen during seizures
    Roaming cortical activation, perhaps semi-random to reactivate cortical circuits during slow wave sleep
    IMPORTANCE OF RT, inhibitory nucleus
  • A1g in dt, ai,h in nrt , leads to differences in bursts
    A1g yellow, a1h red, a1i blue
  • Inhibition, excitation, rebound burst firing resulting from t type ca channels, next
  • Spindles and transients - Sleep Phenomena, Mechanisms and Substrates

    1. 1. Electroencephalogram, Spindles and K complexes
    2. 2. Sleep • The default state • Active Process • Requires synchronizers • Sleep Spindles, K Complexes
    3. 3. Raphe promotes sleep Locus coeruleus promotes wakefulness *so sleep control is distributed across centers
    4. 4. The reticular formation also promotes wakefulness
    5. 5. Stages of sleep form cyclical pattern Slow-Wave Activity: -- Spindles: 7 - 15 Hz ; Wax and Wane -- Delta: 1 - 4 Hz -- Slow Osc. .5 - 1 Hz
    6. 6. Sleep Spindles • Compared to alpha rhythm !! • One of the earliest described events • Hallmark of Synchronization • Requires an oscillator
    7. 7. Midpontine pre- trigeminal Cerebellum Encephale isole‘ Klimesch VO: BioIII Normal sleep-wake cycle including REM Cerveau isole‘ SWS Thalamus Sleep-wake cycle without REM pproximate location of the three cuts for the human brain are below. 7
    8. 8. THALAMUS
    9. 9. Gyri orbitales Gyri frontales Co rp u G. praecentralis G. postcentralis RE Gyri temporales VA VL VP LP Pu LGN MGN Gyri parietales A M ss tri atu m
    10. 10. Thalamocortical Network Ctx + + RE + TC -
    11. 11. Thalamocortical spindle circuitry Modified from Steriade and Llinás. Physiol.Rev. 68:649-742, 1998.
    12. 12. T type calcium channel genes in thalamus α1G α1H α1I Courtesy of E Talley, D Bayliss & E Perez-Reyes
    13. 13. Post inhibitory rebound in thalamic relay neurons -60 Vm -70 -80 Ca2+depende nt rebound burst IPSP threshold 1 hT 0 T channels reprimed 100 ms
    14. 14. Thalamo-cortical reentrant loops. Steriade, M. (1999). Coherent oscillations and short-term plasticity in corticothalamic networks. TINS, Vol. 22 (8), 337-344. Basic Circuitry: Cortex RE Cortex Dorsal Thal. = Relay Nuclei RE L-circ Th-cx Dendro-dendr. Th-cx RE L-circ Aff ‚Secondary neurons‘
    15. 15. 1,2 Afferent brainstem input to Th-cx (1), Activation of RE and Cortex (2) Cortex L-circ RE Th-cx Dendro-dendr. Th-cx RE L-circ Aff
    16. 16. 3 Excitatory processes in Cortex; Inhibition of primary L-circ; Inhibition of other RE cells Cortex L-circ RE Th-cx Dendro-dendr. Th-cx RE L-circ Aff
    17. 17. 4 Excitatory feedback response from cortex. Disinhibition of primary L-circ neurons. Inhibition of secondary Th-cx neurons. The resulting effect is that during time 4, Th-cx are again under inhibitory control from L-circ neurons and, at the same time are activated from cortico-thalamic cells. Thus, only strong (converging and/or amplified) cortical feedback will trigger another excitatory activation wave into the cortex in time 5. Cortex The strong inhibition of the secondary Th-cx cell may lead to low threshold spikes (LTS) and, thus, to a 10 Hz oscillation. L-circ RE Th-cx Th-cx RE L-circ Aff
    18. 18. 5 The primary Th-cx cell may start a new excitatory burst into the cortex. At this stage (because released from the L-circ inhibition), a new afferent input will have a strong effect. The secondary Th-cx cells remain under inhibition RESULT: Center-surround ‚on-off‘ effect with a resulting strong focal activation of cortical target neurons. Cortex RE L-circ Th-cx Th-cx RE L-circ Aff
    19. 19. Summary of findings: Afferent brainstem activation is missing and cortical activation is strong: - Th-cx cells are hyperpolarized and oscillate with spindle frequency Note that a depol. current pulse during maximal hyperpol. leads to high frequency bursts. The result is increased oscillatory cortical activation leading to Delta activity. - The effect of increased cortical activation is even larger if stimulation patterns are oscillatory SLEEP: Spindles and Delta RE Cortex Th-cx hyperpolarized, Sleep spindles L-circ Th-cx Missing brainstem afferents
    20. 20. Spindle oscillations in thalamus A M P A /N M D A R T h a la m u s G A B A AR nR t T C + timing R ebound B u rs t E P S P & B u rs t IP S P 20 m V C o rte x - 200 m s
    21. 21. RE Cell Rapidly bursting type A Mathematical model Foundations II - Neuroimaging
    22. 22. TC Cell modulation by RE cell A Mathematical model
    23. 23. Propagation of Spindles
    24. 24. Ontogeny of Spindles • EEG maturation • Posterior Dominant • Anterior spread • Amplitude decreases with age • Two ditinct frequency bands seen
    25. 25. K Complexes Paroxysmal Events
    26. 26. K Complexes • stage 2 sleep, arousing stimuli. • Loomis et al. (1938); • reason for calling them K complexes remains obscure • spur of the moment • Knocking • K complex shows a maximum over the vertex, • also K complexes with an indubitable maximum over the frontal midline.
    27. 27. • H. Davis et al. - central and frontal K complexes • Brazier (1949) presumed two distinct generators; these were area 6, corresponding with the vertex, and area 9, corresponding with frontal midline. • initial sharp component, followed by a slow component that fuses with a superimposed fast component. • The sharp component is biphasic and not seldom multiphasic. • The slow component is represented by a large slow wave that may exceed 1,000 msec in duration
    28. 28. Positive occipital sharp transients of sleep POSTS start to occur in healthy people at age 4 years, become fairly common by age 15 years, remain common through age 35 years, and start to disappear by age 50 years. POSTS are seen very commonly on EEG and have been said to be more common during daytime naps than during nocturnal sleep. Most characteristics of POSTS are contained in their name. They have a positive maximum at the occiput, are contoured sharply, and occur in early sleep (stages I and II). Their morphology classically is described as "reverse check mark," and their amplitude is 50-100 µV. They typically occur in runs of 4-5 Hz and are bisynchronous, although they may be asymmetric. They persist in stage II sleep but usually disappear in subsequent stag
    29. 29. Vertex sharp transients Also called vertex waves or V waves, these transients are almost universal. Although they often are grouped together with K complexes, strictly speaking, vertex sharp transients are distinct from K complexes. Like K complexes, vertex waves are maximum at the vertex (central midline placement of electrodes [Cz]), so that, depending on the montage, they may be seen on both sides, usually symmetrically. Their amplitude is 50-150 µV. They can be contoured sharply and occur in repetitive runs, especially in children. They persist in stage II sleep but usually disappear in subsequent stages. Unlike K complexes, vertex waves are narrower and more focal and by themselves do not define stage II.

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