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type=\u0022text\/css\u0022 rel=\u0022stylesheet\u0022 href=\u0022\/\/d282kpwvnogo5m.cloudfront.net\/sites\/default\/files\/cdn\/css\/http\/css_Xg7z6oCTVgud_Q0huYz9x9iiD5H_2YPSJ5z2ZViSWdY.css\u0022 media=\u0022all\u0022 \/\u003E\n\u003Clink rel=\u0027stylesheet\u0027 type=\u0027text\/css\u0027 href=\u0027\/sites\/all\/modules\/contrib\/panels\/plugins\/layouts\/onecol\/onecol.css\u0027 \/\u003E\u003C\/head\u003E\u003Cbody\u003E\u003Cdiv class=\u0022panels-ajax-tab-panel panels-ajax-tab-panel-sageoa-tab-art\u0022\u003E\u003Cdiv class=\u0022panel-display panel-1col clearfix\u0022 \u003E\n  \u003Cdiv class=\u0022panel-panel panel-col\u0022\u003E\n    \u003Cdiv\u003E\u003Cdiv class=\u0022panel-pane pane-highwire-markup\u0022 \u003E\n  \n      \n  \n  \u003Cdiv class=\u0022pane-content\u0022\u003E\n    \u003Cdiv class=\u0022highwire-markup\u0022\u003E\u003Cdiv xmlns=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022 id=\u0022content-block-markup\u0022 xmlns:xhtml=\u0022http:\/\/www.w3.org\/1999\/xhtml\u0022\u003E\u003Cdiv class=\u0022article fulltext-view \u0022\u003E\u003Cspan class=\u0022highwire-journal-article-marker-start\u0022\u003E\u003C\/span\u003E\u003Cdiv class=\u0022section abstract\u0022 id=\u0022abstract-1\u0022\u003E\u003Ch2\u003ESummary\u003C\/h2\u003E\n            \u003Cp id=\u0022p-1\u0022\u003EThe FAER-Helrich Research Lecture focused on how neuroscience research is rapidly changing our understanding of anesthesia and how a deeper understanding of neuroscience can change patient care. Specific topics include the neural circuit mechanisms of commonly used anesthetics, electroencephalogram (EEG) signatures, how EEGs and their spectrograms can be used to track the state of anesthesia, how to control sedation, and how the brain dynamics under anesthesia change with age.\u003C\/p\u003E\n         \u003C\/div\u003E\u003Cul class=\u0022kwd-group\u0022\u003E\u003Cli class=\u0022kwd\u0022\u003ENeuroimaging Neuroimaging\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003EGeneral Anesthesia\u003C\/li\u003E\u003C\/ul\u003E\u003Cul class=\u0022kwd-group clinical-trial\u0022\u003E\u003Cli class=\u0022kwd\u0022\u003ENeuroimaging\u003C\/li\u003E\u003Cli class=\u0022kwd\u0022\u003EGeneral Anesthesia\u003C\/li\u003E\u003C\/ul\u003E\u003Cp id=\u0022p-2\u0022\u003EEmery N. Brown, MD, PhD, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA, presented the American Society of Anesthesiologists\u0027 FAER\u2013Helrich Research Lecture. Dr Brown\u0027s lecture focused on how neuroscience research is rapidly changing our understanding of anesthesia and how a deeper understanding of neuroscience can change patient care. During his presentation, Dr Brown reviewed the neural circuit mechanisms of commonly used anesthetics, electroencephalogram (EEG) signatures, how EEGs and their spectrograms can be used to track the state of anesthesia, how to control sedation, and how the brain dynamics under anesthesia change with age.\u003C\/p\u003E\u003Cp id=\u0022p-3\u0022\u003EGeneral anesthesia is defined as a drug\u2013induced, reversible state composed of unconsciousness, amnesia, analgesia, akinesia, stability, and control. It is essential for performing most major surgical procedures. While under general anesthesia, patients experience several altered states of arousal: sedation unconsciousness, sedation analgesia, dissociative anesthesia, pharmacologic non\u2013rapid eye movement sleep, and neuroleptic anesthesia. Each of these states is the result of the anesthetic drug acting at multiple targets in the central nervous system. Different drugs act at different sites [Brown EN et al. \u003Cem\u003EAnnu Rev Neurosci.\u003C\/em\u003E 2011] and can be tracked along the affected neural circuits. Understanding the relationship between this circuit and the affected body part can provide insight into the drug\u0027s action.\u003C\/p\u003E\u003Cp id=\u0022p-4\u0022\u003EIt is sometimes said that EEGs provide a \u201cnoisy\u201d signal. Although this may be true, when used in environments like a sleep laboratory in which patients are moving about, EEGs can be used to clearly mark the progression from consciousness to unconsciousness in patients who are anesthetized.\u003C\/p\u003E\u003Cp id=\u0022p-5\u0022\u003EEEG spectral signatures that track loss and recovery of consciousness under general anesthesia (eg, propofol) show a rise in frontal persistent and synchronous \u03b1 activity at dose levels sufficient to induce loss of consciousness [Ching S et al. \u003Cem\u003EProc Natl Acad Sci U S A\u003C\/em\u003E. 2010]. By combining spectral and global coherence analyses, a new approach to tracking brain states under general anesthesia is proving to be valuable [Cimenser A et al. \u003Cem\u003EProc Natl Acad Sci U S A\u003C\/em\u003E. 2011].\u003C\/p\u003E\u003Cp id=\u0022p-6\u0022\u003EUsing propofol as an example, Dr Brown offered the following explanation of how anesthesia produces unconsciousness. Propofol acts at presynaptic and postsynaptic GABA\u003Csub\u003EA\u003C\/sub\u003E receptors within GABAergic synapses creating oscillations including \u03b1 (8\u201312 Hz) rhythms that strongly couple the thalamus and cortex areas restricting communication, slow\u2013wave (\u0026lt; 1 Hz) rhythms that create local islands preventing local cortex communication, and anteriorization, which acts as a mechanism for frontal\u2013parietal disconnection [Purdon PL et al. \u003Cem\u003EProc Natl Acad Sci U S A\u003C\/em\u003E. 2013]. Communication between the lower parts of the brain and the cortex is impeded by blocking the brain stem arousal pathways. Different anesthetics act on different systems and have different EEG signatures and power spectrum structures. Knowledge of these neural circuits and individual drug signatures is important for understanding how and where the anesthesia is working.\u003C\/p\u003E\u003Cp id=\u0022p-7\u0022\u003EThe development state of the brain affects how anesthesia will work. Total EEG power peaks between 4 and 8 years of age, and then begins to drop off. Spatiotemporal spectrogram analysis shows a difference in EEG wave development between infants aged 0 to 3 months and those aged 4 to 6 months, with slow waves being more prominent in the younger infants.\u003C\/p\u003E\u003Cp id=\u0022p-8\u0022\u003EBurst suppression is a state of brain inactivation in which bursts of electrical activity alternate with periods of quiescence or suppression. It is seen in patients under general anesthesia, individuals with hypothermia, and among infants with early infantile epileptic encephalopathy or refractory seizures, each of whom demonstrate a clear pattern. Burst suppression is also seen in patients in a coma and can be manipulated to achieve a medically induced coma to treat various conditions or to protect the brain from further injury. One way to induce a coma is by manually titrating and maintaining the anesthesia infusion rate to a specified level. Medical personnel currently rely on visually monitoring the EEG to maintain appropriate levels of burst suppression. A promising alternative is the use of a brain\u2013machine interface device for maintenance. One such device has been shown to maintain precise target levels of burst suppression by monitoring an EEG\u2013guided closed\u2013loop infusion of the anesthetic. In an animal model of medically induced coma using propofol, a brain\u2013machine interface device accurately controlled burst suppression with a median performance error of 3.6%, and a median bias of \u22121.4% and overall posterior probability of reliable control of 1 was observed (95% Bayesian credibility interval, 0.87 to 1.0; \u003Ca id=\u0022xref-fig-1-1\u0022 class=\u0022xref-fig\u0022 href=\u0022#F1\u0022\u003EFigure 1\u003C\/a\u003E) [Shanechi MM et al. \u003Cem\u003EPLoS Comput Biol.\u003C\/em\u003E 2013].\u003C\/p\u003E\u003Cdiv id=\u0022F1\u0022 class=\u0022fig pos-float  odd\u0022\u003E\u003Cdiv class=\u0022highwire-figure\u0022\u003E\u003Cdiv class=\u0022fig-inline-img-wrapper\u0022\u003E\u003Cdiv class=\u0022fig-inline-img\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/14\/40\/8\/F1.large.jpg?width=800\u0026amp;height=600\u0026amp;carousel=1\u0022 title=\u0022A Brain\u0026#x2013;Machine Interface Approach to Control Burst Suppression and Coma Level in a Rat Model\u0022 class=\u0022fragment-images colorbox-load\u0022 rel=\u0022gallery-fragment-images-1097763666\u0022 data-figure-caption=\u0022A Brain\u0026#x2013;Machine Interface Approach to Control Burst Suppression and Coma Level in a Rat Model\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003E\u003Cimg class=\u0022fragment-image\u0022 alt=\u0022Figure 1.\u0022 src=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/14\/40\/8\/F1.medium.gif\u0022\/\u003E\u003C\/a\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cul class=\u0022highwire-figure-links inline\u0022\u003E\u003Cli class=\u00220 first\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/14\/40\/8\/F1.large.jpg?download=true\u0022 class=\u0022highwire-figure-link highwire-figure-link-download\u0022 title=\u0022Download Figure 1.\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload figure\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u00221\u0022\u003E\u003Ca href=\u0022http:\/\/d282kpwvnogo5m.cloudfront.net\/content\/spmdc\/14\/40\/8\/F1.large.jpg\u0022 class=\u0022highwire-figure-link highwire-figure-link-newtab\u0022 target=\u0022_blank\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EOpen in new tab\u003C\/a\u003E\u003C\/li\u003E\u003Cli class=\u00222 last\u0022\u003E\u003Ca href=\u0022\/highwire\/powerpoint\/15114\u0022 class=\u0022highwire-figure-link highwire-figure-link-ppt\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EDownload powerpoint\u003C\/a\u003E\u003C\/li\u003E\u003C\/ul\u003E\u003C\/div\u003E\u003Cdiv class=\u0022fig-caption attrib\u0022\u003E\u003Cspan class=\u0022fig-label\u0022\u003EFigure 1.\u003C\/span\u003E \n            \u003Cp id=\u0022p-9\u0022 class=\u0022first-child\u0022\u003EA Brain\u2013Machine Interface Approach to Control Burst Suppression and Coma Level in a Rat Model\u003C\/p\u003E\n         \u003Cq class=\u0022attrib\u0022 id=\u0022attrib-1\u0022\u003EEEG, electroencephalogram.\u003C\/q\u003E\u003Cq class=\u0022attrib\u0022 id=\u0022attrib-2\u0022\u003EReprinted from Shanechi MM et al. A brain\u2013machine interface for control of medically\u2013induced coma. PLoS \u003Cem\u003EComput\u003C\/em\u003E Biol, 2013; DOI: 10.1371\/journal.pcbi.1003284. Copyright: \u00a9 2013 Shanechi et al.\u003C\/q\u003E\u003Cdiv class=\u0022sb-div caption-clear\u0022\u003E\u003C\/div\u003E\u003C\/div\u003E\u003C\/div\u003E\u003Cp id=\u0022p-10\u0022\u003EFor most patients, emergence from anesthesia is a passive event; however, at times it may be necessary or even beneficial to actively speed\/manage this process. A number of drugs have been used to achieve this. Results from a recent study in rats under general anesthesia with isoflurane or propofol demonstrated that electrical stimulation of the ventral tegmental area can be used to induce a graded arousal response and a shift in EEG peak power that increased with current intensity [Solt K et al. \u003Cem\u003EAnesthesiology\u003C\/em\u003E. 2014]. This may provide a novel, nondrug approach to hasten recovery from general anesthesia or to treat postemergence problems.\u003C\/p\u003E\u003Cp id=\u0022p-11\u0022\u003EIn conclusion, Dr Brown emphasized the complex nature of the state of general anesthesia and its many associations with other altered states of consciousness (eg, sleep, hibernation, meditation, and drug addiction). A better understanding of EEGs can be used to manage patients in the operating room. It is also possible to integrate molecular information with neural circuits, EEG dynamics (neurophysiology), and behavior. This requires that the anesthesiologists have a deeper neuroscience understanding of neuroanatomy and neurophysiology with an emphasis on neural circuits, the need for a clinical neurology examination, working knowledge of neurophysiology of the brain\u0027s EEG, and a good understanding of brain and central nervous system\u2013based pharmacology.\u003C\/p\u003E\u003Cul class=\u0022copyright-statement\u0022\u003E\u003Cli class=\u0022fn\u0022 id=\u0022copyright-statement-1\u0022\u003E\u00a9 2014 MD Conference Express\u00ae\u003C\/li\u003E\u003C\/ul\u003E\u003Cspan class=\u0022highwire-journal-article-marker-end\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Cspan id=\u0022related-urls\u0022\u003E\u003C\/span\u003E\u003C\/div\u003E\u003Ca href=\u0022http:\/\/mdc.sagepub.com\/content\/14\/40\/8.abstract\u0022 class=\u0022hw-link hw-link-article-abstract\u0022 data-icon-position=\u0022\u0022 data-hide-link-title=\u00220\u0022\u003EView Summary\u003C\/a\u003E\u003C\/div\u003E  \u003C\/div\u003E\n\n  \n  \u003C\/div\u003E\n\u003C\/div\u003E\n  \u003C\/div\u003E\n\u003C\/div\u003E\n\u003C\/div\u003E\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/mdc.sagepub.com\/sites\/all\/modules\/highwire\/highwire\/plugins\/highwire_markup_process\/js\/highwire_figures.js?nzom9e\u0022\u003E\u003C\/script\u003E\n\u003Cscript type=\u0022text\/javascript\u0022 src=\u0022http:\/\/mdc.sagepub.com\/sites\/all\/modules\/highwire\/highwire\/plugins\/highwire_markup_process\/js\/highwire_openurl.js?nzom9e\u0022\u003E\u003C\/script\u003E\n\u003C\/body\u003E\u003C\/html\u003E"}