Dynamic changes of somatosensory evoked potentials in rats and

humans during wake-sleep states

Institute of Cognitive Science, National Cheng Kung University

國立成功大學 認知科學所蕭富仁 (Fu-Zen Shaw)

Biological rhythm

• Rhythms are ubiquitous in the mammalian CNS. They also span a broad range of frequencies, from 100 Hz EEG to once per year (0.00000003 Hz) for many seasonal behaviors. They also influence the physiological states (respiratory and cardiac rhythms).

• The earth is a rhythmic environment.

• Brains have evolved a variety of systems for rhythmic control. (e.g., waking and sleep, cardiac rhythm, breathing cycle)

Brain rhythms• Alpha rhythm (8-13 Hz) appears at the occipital cortex w

hen eyes close. [resting condition] {rolandic mu rhythm; temporal tau rhythm}

• Beta rhythm (13-30 Hz) is associated with alertness.

• Gamma rhythm (30-80 Hz) is related to sensory integration and feature binding.

• Theta rhythm (4-8 or 4-10 Hz)

• Delta rhythm (0.5-4 or 1-4 Hz)

• Sleep spindle (12-15 Hz or 7-15 Hz) {sigma rhythm}

• K complex (<0.5 Hz) {(very) slow oscillation}

Brain activities with eye-open and eye-close states

清醒 -睡眠之腦電波特性 (ultradian rhythm)

Ogilvie, Sleep Med. Rev., 5, 247-270, 2001.

Successive EEG changes throughout the sleep onset period

Characteristic patterns of the brain activities in the neocortex and hippocampus

Buzsaki, Neuroscience, 31, 551-70, 1989. Gottesmann, Neurosci. Biobehav. Rev., 16, 31-8, 1992.Steriade et al., Science, 262, 679-85, 1993.Steriade, Neuroscience, 101, 243-76, 2000.

Awake Non-REM sleep REM sleepStage 1 Stage 2 Stage 3-4

Cortex Alpha wave

Gamma wave

Spindle

K complex

Delta wave Theta wave

Gamma wave

Hippocampus Theta wave

HVS

High-voltage spike (HVS) with high-frequency ripple (~200 Hz)

Theta wave

Brain rhythms in wake-sleep states

Shaw et al., Sleep, 29, 276-284, 2006.

Somatosensory pathway & Somatotopography

SEP changes during wake-sleep states

Shaw et al., Sleep, 29, 276-284, 2006.

Frequency response of EPs

Castro-Alamancos, Prog. Neurobiol., 74, 213-247, 2004.

Augmenting response in cortical neurons during 80-150 ms inter-stimulus intervals

Castro-Alamancos and Connors, Science, 272, 274-277, 1996.

Short-term plasticity:

Augmenting response in cortical neurons by 10-Hz stimulation

Steriade, Trends Neurosci., 22, 337-345, 1999.

Frequency response of SEPs in wake-sleep states

Shaw et al., Sleep, 29, 276-284, 2006.

SEP changes in sleep and absence epilepsy

Shaw et al., Sleep, 29, 276-284, 2006.

Binding problem & winner-take-all strategy

Binding problem & winner-take-all strategyBinding problem & winner-take-all strategy

Two gamma responses: evoked vs. induced

Tallon-Baudry and Bertrand, Trends Cog. Sci., 3, 151-162, 1999.

Tallon-Baudry and Bertrand, Trends Cog. Sci., 3, 151-162, 1999.

Eevoked auditory gamma activity during wake-sleep states

Llinas and Ribary, Proc. Natl. Acad. Sci. USA, 90, 2078-2081, 1993.

Evoked responses

Spontaneous

Evoked visual gamma activity in various brain areas

Schurmann et al., NeuroReport, 8, 531-534, 1997.

Evoked auditory gamma activity in various brain areas

Basar et al., IEEE Eng. Bio. Med., 14, 400-410, 1995.Shaw and Chew, Brain Res., 983: 152-161, 2003.

Shaw and Chew, Brain Res., 983: 152-163, 2003.

Gamma responses of the rat’s SEPs in wake-sleep states

Gamma responses of the rat’s SEPs in wake-sleep states

Shaw and Chew, Brain Res., 983: 152-163, 2003.

Changes of cortical somatosensory evoked potentials using medial nerve stimulation durin

g wake-sleep states

+

-

P1

N1

1 2

*P <.05 vs S2; #P <.05 vs SWS; +P <.05 vs REM by Student-Newman-Keuls test.

Theta wave analysis

SEP changes in sleep spindles

Stickgold, Nat. Neurosci., 10, 540-542, 2007.

Miller, Science, 315, 1360-1363, 2007.

Maquet, Science, 294, 1048-1052, 2001.

The role of sleep in brain plasticity

Dual process:

SWS is favorable to explicit memory traces REM sleep is involved in implicit memory consolidation

Double-step process:

Consolidation of memory traces requires SWS followed by REM sleep

Two-stage processes to external stimulation: SWS (sleep spindle) is beneficial for enhancement of inputs, and REM sleep for integrating/binding inputs.

Acknowledgement

National Cheng Kung UniversityS.-F. Liang (梁勝富 )

National Taiwan UniversityC.-T. Yen (嚴震東 )

Graduate StudentsJ.-H. Chew (周佳禾 )S.-Y. Lee (李姝瑩 )T.-Y. Chuang (莊子宜 )