I should restate, for simplicity, that my question really is:<div><br></div><div>What does the MEG signal &quot;mean&quot; in an empty room setting?</div><div>In a setting with zero change in magnetic flux?</div><div>What would be some appropriate resources to draw upon to examine this more?</div>


<div><br></div><div>The answers could relate to the behavior of the SQUIDs themselves, or to all the other hardware downstream of them. I&#39;m just trying to get a fuller picture of what is happening during such null cases.<br>

<br><div class="gmail_quote">On Fri, Mar 4, 2011 at 6:15 PM, Jeff Alstott <span dir="ltr">&lt;<a href="mailto:[log in to unmask]" target="_blank"><a href="/cgi-bin/wa-jisc.exe?LOGON=A3%3Dind1103%26L%3DNEUROMEG%26E%3Dquoted-printable%26P%3D4366%26B%3D--0016e6d9728654a2c8049dfdc3b6%26T%3Dtext%252Fhtml%3B%2520charset%3DISO-8859-1%26pending%3D" target="_parent" >[log in to unmask]</a></a>&gt;</span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hello all,<div><br></div><div>I am analyzing data from a Neuromag Vectorview system for evidence of critical phenomena, and empty rooms keep puzzling me. I am still quite new to MEG, but my analysis of the &quot;signal&quot; seen from an empty room, with proper shielding, shows signatures of a system at criticality. This is surprising to me. </div>



<div><br></div><div>While I have no experience with SQUIDs, an initial literature search seemed to show that SQUIDs have critical dynamics when there is no external magnetic flux. Is this correct? What would be some further resources to understand what the MEG signal &quot;means&quot; in an empty room setting?</div>



<div><br></div><div>Thank you for your help!</div><div>Jeff Alstott</div><font color="#888888"><div>Cambridge, BCNI</div><div>US NIH, NIMH</div><div><br></div>
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