Editing Dream (section)

== Neurophysiology ==
{{Main|Cognitive neuroscience of dreams}}
{{Further|Neuroscience of sleep}}

Dream study is popular with scientists exploring the [[mind–body problem|mind–brain problem]]. Some "propose to reduce aspects of dream phenomenology to neurobiology."<ref>{{cite journal |last1=Hobson |first1=J. Allan |last2=Pace-Schott |first2=Edward F. |last3=Stickgold |first3=Robert |author-link1=Allan Hobson |title=Dream science 2000: A response to commentaries on ''Dreaming and the Brain'' |journal=Behavioral and Brain Sciences |year=2000 |volume=23 |issue=6 |page=1019 |doi=10.1017/S0140525X00954025 |s2cid=144729368}}</ref> But current science cannot specify dream physiology in detail. Protocols in most nations restrict human brain research to non-invasive procedures. In the United States, invasive brain procedures with a human subject are allowed only when these are deemed necessary in surgical treatment to address medical needs of the same human subject.<ref>{{cite journal |last1=Chiong |first1=Winston |last2=Leonard |first2=Matthew K. |last3=Chang |first3=Edward F. |title=Neurosurgical Patients as Human Research Subjects: Ethical Considerations in Intracranial Electrophysiology Research |journal=Neurosurgery |year=2018 |volume=83 |issue=1 |pages=29–37 |doi=10.1093/neuros/nyx361 |pmid=28973530 |url=https://academic.oup.com/neurosurgery/article-abstract/83/1/29/3988112 |pmc=5777911}}</ref> Non-invasive measures of brain activity like [[electroencephalogram]] (EEG) voltage averaging or [[functional magnetic resonance imaging|cerebral blood flow]] cannot identify small but influential neuronal populations.<ref name="hob">Hobson, J. A., Pace-Schott, E. F., & Stickgold, R. (2000). "Dreaming and the brain: Toward a cognitive neuroscience of conscious states". ''Behavioral and Brain Sciences'', 23(6), 793–842.</ref> Also, [[functional magnetic resonance imaging|fMRI]] signals are too slow to explain how brains compute in real time.<ref>{{cite web |url=https://speakingofresearch.com/2009/07/31/the-limits-of-fmri/ |title=The limits of fMRI |last=Ringach |first=Dario L. |date=30 July 2009 |publisher=Speaking of Research |access-date=18 July 2021}}</ref>

Scientists researching some brain functions can work around current restrictions by examining animal subjects. As stated by the [[Society for Neuroscience]], "Because no adequate alternatives exist, much of this research must ''[sic]'' be done on animal subjects."<ref>{{cite web |url=https://www.sfn.org/Advocacy/Policy-Positions/Policies-on-the-Use-of-Animals-and-Humans-in-Research |title=Policies on the Use of Animals and Humans in Research |publisher=Society for Neuroscience |access-date=18 July 2021}}</ref> However, since animal dreaming can be only inferred, not confirmed, animal studies yield no hard facts to illuminate the neurophysiology of dreams. Examining human subjects with brain lesions can provide clues, but the lesion method cannot discriminate between the effects of destruction and disconnection and cannot target specific neuronal groups in heterogeneous regions like the brain stem.<ref name="hob"/>