<?xml version="1.0" encoding="utf-8"?><!DOCTYPE article  PUBLIC '-//OASIS//DTD DocBook XML V4.4//EN'  'http://www.docbook.org/xml/4.4/docbookx.dtd'><article><articleinfo><title>ParametricModulation</title><revhistory><revision><revnumber>14</revnumber><date>2013-03-08 10:28:25</date><authorinitials>localhost</authorinitials><revremark>converted to 1.6 markup</revremark></revision><revision><revnumber>13</revnumber><date>2008-06-03 17:12:04</date><authorinitials>devel03.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>12</revnumber><date>2007-07-30 17:26:21</date><authorinitials>IanNimmoSmith</authorinitials></revision><revision><revnumber>11</revnumber><date>2007-07-25 18:24:01</date><authorinitials>devel03.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>10</revnumber><date>2007-07-25 14:30:46</date><authorinitials>devel03.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>9</revnumber><date>2007-07-25 14:30:22</date><authorinitials>devel03.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>8</revnumber><date>2007-07-24 16:23:50</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>7</revnumber><date>2007-07-10 12:50:55</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>6</revnumber><date>2007-07-10 11:21:39</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>5</revnumber><date>2007-07-10 11:17:21</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>4</revnumber><date>2007-07-10 11:08:42</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>3</revnumber><date>2007-07-10 10:45:17</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>2</revnumber><date>2007-07-10 10:37:45</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision><revision><revnumber>1</revnumber><date>2007-07-10 10:34:57</date><authorinitials>devel06.mrc-cbu.cam.ac.uk</authorinitials></revision></revhistory></articleinfo><section><title>Parametric modulation</title><para>The problem of constrained modeling of parametric modulation across events, allowing for flexible relationship between signal and parameter.   </para><section><title>Subversion repository</title><para>At: <ulink url="http://imaging.mrc-cbu.cam.ac.uk/svn/parameters/devel"/> </para><para>For example: </para><para><code>svn co http://imaging.mrc-cbu.cam.ac.uk/svn/parameters/devel parameters</code> </para><para>Then edit some file. </para><para>Then: </para><para><code>svn commit -m 'A comment'</code> </para><para>And: </para><para><code>cd parameters; svn update</code> </para><para>to get the latest repository data into your working copy in the <code>parameters</code> subdirectory. </para></section><section><title>Work so far</title><para>The event-related study of Brett et al:  </para><para><ulink url="http://www.mrc-cbu.cam.ac.uk/~matthew/abstracts/ER/er_analysis.html"/> </para><para>Parametric modulation approach described in: </para><itemizedlist><listitem override="none"><para>Estimating effects on effects using the Varying Coefficient Models by Ferath Kherif, Emmanuel A Stamatakis, Cristina Ramponi,Matthew Brett, Ian Nimmo-Smith, and Lorraine K Tyler </para></listitem></itemizedlist><para><ulink url="http://www.mrc-cbu.cam.ac.uk/Statistics/Methods/Resources/ferath_hbm2005.pdf"/> </para></section><section><title>The dataset</title><para>Described in Brett et al abstract and poster above. </para><para>Visual checkerboard events at random intervals.  Sessions for which events are rapid (mean ISI 1 second) to slow (mean ISI 10 seconds).  Evidence that interval between current and last event influences height and possibly shape of response.  We wanted to be able to fit a curve relating the height of the event to the parametric modulator of time since last event.   </para><para>We used region of interest time courses from the visual cortex to stabilize the signal.  </para></section><section><title>Code so far</title><para>Implemented in matlab, by Ferath and Ian.  No modeling of </para><para>Ian has written a technical note in latex: </para><para><ulink url="http://imaging.mrc-cbu.cam.ac.uk/svn/parameters/devel/docs/smoothed.tex"/> </para><para>and the current pdf version is at: </para><para><ulink url="http://imaging.mrc-cbu.cam.ac.uk/svn/parameters/devel/docs/smoothed.pdf"/> </para></section><section><title>Approach to problem</title><itemizedlist><listitem><para>Proper modeling of autocorrelation - maybe using R routines </para></listitem><listitem><para>Modeling on ROI time-courses </para></listitem><listitem><para>Model individual events, and constrain to have smooth relationship to paramter </para></listitem></itemizedlist></section><section><title>Plan</title><itemizedlist><listitem><para>Reimplement model for ROI time course in NIPY - done - see <ulink url="http://imaging.mrc-cbu.cam.ac.uk/svn/parameters/devel/scripts/"/> </para></listitem><listitem><para>Address autocorrelation - partly done - can now run AR models with scipy,models code </para></listitem><listitem><para>Implement parametric modulation within scipy.models </para><itemizedlist><listitem><para>Find suitable interface for expressing constrained modulation for models </para></listitem></itemizedlist></listitem></itemizedlist><para>See <ulink url="https://imaging.mrc-cbu.cam.ac.uk/methods/ParametricModulation/methods/WorkingOutNipy#">WorkingOutNipy</ulink> for musings on the code structure of NIPY </para></section><section><title>Analyses in R via rpy</title><para>See <ulink url="https://imaging.mrc-cbu.cam.ac.uk/methods/ParametricModulation/methods/SCodebits#">SCodebits</ulink> for the SPlus code that we used in 2003. Will try to get these running in R and use the <emphasis role="strong">rpy</emphasis> R-to-python interface to compare these analyses with the current NIPY approach. </para><para><ulink url="https://imaging.mrc-cbu.cam.ac.uk/methods/ParametricModulation/methods/IanNimmoSmith#">IanNimmoSmith</ulink>, <ulink url="https://imaging.mrc-cbu.cam.ac.uk/methods/ParametricModulation/methods/MatthewBrett#">MatthewBrett</ulink> </para></section></section></article>