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 ( 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 when 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, , Successive EEG changes throughout the sleep onset period

Characteristic patterns of the brain activities in the neocortex and hippocampus Buzsaki, Neuroscience, 31, , Gottesmann, Neurosci. Biobehav. Rev., 16, 31-8, Steriade et al., Science, 262, , Steriade, Neuroscience, 101, , AwakeNon-REM sleepREM sleep Stage 1Stage 2Stage 3-4 CortexAlpha wave Gamma wave Spindle K complex Delta wave Theta wave Gamma wave HippocampusTheta 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, , 2006.

Somatosensory pathway & Somatotopography

SEP changes during wake-sleep states Shaw et al., Sleep, 29, , 2006.

Frequency response of EPs Castro-Alamancos, Prog. Neurobiol., 74, , 2004.

Augmenting response in cortical neurons during ms inter- stimulus intervals Castro-Alamancos and Connors, Science, 272, , 1996.

Short-term plasticity: Augmenting response in cortical neurons by 10-Hz stimulation Steriade, Trends Neurosci., 22, , 1999.

Frequency response of SEPs in wake-sleep states Shaw et al., Sleep, 29, , 2006.

SEP changes in sleep and absence epilepsy Shaw et al., Sleep, 29, , 2006.

Binding problem & winner-take-all strategy

Two gamma responses: evoked vs. induced Tallon-Baudry and Bertrand, Trends Cog. Sci., 3, , 1999.

Eevoked auditory gamma activity during wake-sleep states Llinas and Ribary, Proc. Natl. Acad. Sci. USA, 90, , Evoked responses Spontaneous

Evoked visual gamma activity in various brain areas Schurmann et al., NeuroReport, 8, , 1997.

Evoked auditory gamma activity in various brain areas Basar et al., IEEE Eng. Bio. Med., 14, , Shaw and Chew, Brain Res., 983: , 2003.

Shaw and Chew, Brain Res., 983: , Gamma responses of the rat’s SEPs in wake-sleep states

Shaw and Chew, Brain Res., 983: , 2003.

Changes of cortical somatosensory evoked potentials using medial nerve stimulation during 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, , 2007.

Miller, Science, 315, , 2007.

Maquet, Science, 294, , 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 University S.-F. Liang ( 梁勝富 ) National Taiwan University C.-T. Yen ( 嚴震東 ) Graduate Students J.-H. Chew ( 周佳禾 ) S.-Y. Lee ( 李姝瑩 ) T.-Y. Chuang ( 莊子宜 )