Lecture27 - BioNB222 Cornell University Spring 2008 Andrew...

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Unformatted text preview: BioNB222 Cornell University Spring 2008 Andrew H. Bass Lecture 27. Sleeping, Dreaming, Waking Reading Assignment: Purves, Chapter 28 Lecture Outline GOALS: Demonstrate how the brain contributes to the generation of large-scale, rhythmic behaviors such as sleep and wakefulness. A. A Brain Clock for Sleep and Wakefulness (P, Fig. 28.5)? 1. the candidate for the primary clock in the brain is the suprachiasmatic nucleus (SCN) of the hypothalamus. 2. light is the principal entraining stimulus for the SCN clock retinal photoreceptors transmit photic information to the SCN via a retinohypothalamic pathway 3. The SCN is linked to effector systems that can control various physiological and behavioral functions, such as sleep and wakefulness. BioNB222 Cornell University Spring 2008 Andrew H. Bass B. Electroencephalograms or EEGS (P Box 28C, p. 715-717) provide us with peeks at large scale brain activity, their amplitude being dependent on the synchronous activity of neurons in the cerebral cortex which lies under the scalp. EEGs were first observed by Hans Berger in 1929, who noted differences in the EEGs of sleeping and awake individuals. 1. Waking state: ---- Beta rhythm ---- Alpha rhythm 2. Sleep: The Stuff That Dreams Are Made Of (P - Figs. 28.6, 28.7). Characterized by EEG, sensations, thought, whole body movement, eye movement. Two major function al categories of sleep: non-REM (rapid eye movement) and REM BioNB222 Cornell University Spring 2008 Andrew H. Bass C. Arousal systems: Neurochemistry of Sleep & Wakefulness (P - Fig. 28.11; Table 28.1 - p. 725) A "reticular activating system" within the center or core of the midbrain and hindbrain includes three major chemically defined groups of neurons that are generally referred to as the reticular activating system. The word reticular is used because these neurons are positioned within brain regions that have a reticulated appearance a dense weave of neurons and axons. Study Questions: 1. Compare the overall activity state of the body between REM sleep and an awake state. 2. Compare the location of a ganglion cell in the visual system to a ganglion cell in the visceral motor system. 3. How does the firing pattern of a thalamocortical neurons differ between sleep and awake states? BioNB222 Cornell University Spring 2008 Andrew H. Bass ...
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