<article_title>Brain</article_title>
<edit_user>Hordaland</edit_user>
<edit_time>Tuesday, September 15, 2009 10:58:01 AM CEST</edit_time>
<edit_comment>/* Arousal system */  // All NREM is NOT slow wave! and &amp;quot;the pattern becomes&amp;quot; --&amp;gt; &amp;quot;patterns become&amp;quot;</edit_comment>
<edit_text>Sleep involves great changes in brain activity.&lt;ref&gt;Principles of Neural Science, Ch. 47&lt;/ref&gt; Until the 1950s it was generally believed that the brain essentially shuts off during sleep,&lt;ref&gt;Kleitman, Nathaniel (1938, revised 1963, reprinted 1987) Sleep and Wakefulness (Introduction). The University of Chicago Press, Midway Reprints series, ISBN 0-226-44073-7 &lt;/ref&gt; but this is now known to be far from true: activity continues, but the pattern becomes very different. In fact, there are two types of sleep, slow wave sleep (usually non-dreaming) and<strong><strike>REM sleep'' (dreaming), each with its own</strike></strong><strong>NREM'' (non-REM, usually without dreaming) sleep, which repeat in slightly varying patterns throughout a sleep episode.  Three broad types of</strong> distinct brain activity patterns can be measured: REM, light NREM and deep NREM. During deep NREM sleep, also called slow wave sleep, activity in the cortex takes the form of large synchronized waves, where in the waking state it is noisy and desynchronized. Levels of the neurotransmitters norepinephrine and serotonin drop during slow wave sleep, and fall almost to zero during REM sleep; levels of acetylcholine show the reverse pattern.</edit_text>
<turn_user>Tryptofish<turn_user>
<turn_time>Tuesday, September 15, 2009 12:56:56 AM CEST</turn_time>
<turn_topicname>missing illustration?</turn_topicname>
<turn_topictext>The last paragraph of the section Microscopic structure refers to an "illustration on the right" which seems to have gone missing. Either the image should be re-added, or the reference to it should be removed. - Hordaland (talk) 00:36, 15 September 2009 (UTC) Yeeks, you are right! I've looked back through the page history, and it wasn't deleted by mistake any time recently. I'll correct the text. Thanks for finding that! --Tryptofish (talk) 00:56, 15 September 2009 (UTC)</turn_topictext>
<turn_text>Yeeks, you are right! I've looked back through the page history, and it wasn't deleted by mistake any time recently. I'll correct the text. Thanks for finding that! </turn_text>