<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><br><div><br><div>Begin forwarded message:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="4" color="#000000" style="font: 14.0px Helvetica; color: #000000"><b>From: </b></font><font face="Helvetica" size="4" style="font: 14.0px Helvetica">Anirvan Ghosh <<a href="mailto:aghosh@ucsd.edu">aghosh@ucsd.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="4" color="#000000" style="font: 14.0px Helvetica; color: #000000"><b>Date: </b></font><font face="Helvetica" size="4" style="font: 14.0px Helvetica">June 5, 2009 2:30:22 PM PDT</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="4" color="#000000" style="font: 14.0px Helvetica; color: #000000"><b>To: </b></font><font face="Helvetica" size="4" style="font: 14.0px Helvetica">Neuro GradStudents <<a href="mailto:neuro-students-l@ucsd.edu">neuro-students-l@ucsd.edu</a>>, Neuro Faculty <<a href="mailto:neuro-faculty-l@ucsd.edu">neuro-faculty-l@ucsd.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="4" color="#000000" style="font: 14.0px Helvetica; color: #000000"><b>Cc: </b></font><font face="Helvetica" size="4" style="font: 14.0px Helvetica">Libby Weber <<a href="mailto:e1weber@ucsd.edu">e1weber@ucsd.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="4" color="#000000" style="font: 14.0px Helvetica; color: #000000"><b>Subject: </b></font><font face="Helvetica" size="4" style="font: 14.0px Helvetica"><b>[Neuro-faculty-L]<span class="Apple-converted-space"> </span>Special Seminar: Anne Churchland, June 12th</b></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div> </div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div apple-content-edited="true"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; "><b>Special Seminar</b></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; "><div><font class="Apple-style-span" size="4"><b>Anne Churchland, University of Washington</b></font></div><div><font class="Apple-style-span" size="4"><b>Mechanisms for understanding decisions of increasing complexity</b></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b><br></b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b>Friday, June 12th, 12:00 pm</b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b>NSB auditorium</b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b><br></b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b>Hosts: David Kleinfeld and Anirvan Ghosh</b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b><br></b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b>_____</b></span></font></div><div><font class="Apple-style-span" size="4"><span class="Apple-style-span" style="font-size: 14px;"><b> <!--StartFragment--><p class="MsoNormal" style="margin-right:-9.0pt"><span class="Apple-style-span" style="font-weight: normal;">Abstract</span></p><p class="MsoNormal" style="margin-right:-9.0pt"><span style="font-family:Arial"><span style="mso-tab-count:1"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">Simple perceptual tasks have provided a preliminary foundation for understanding the neurobiology of decision-making. In these experiments, human or monkey subjects report the direction of a random dot motion stimulus with a saccade. Physiology experiments have suggested that the accumulation of sensory evidence is reflected in firing rates in the lateral intraparietal area (LIP). The decision process ends when the accumulated evidence reaches a threshold level or bound: the option corresponding to that bound is taken as the choice. This class of mechanisms has helped connect the physiology with the monkeys’ speed and accuracy for very simple decisions. However, it is not known whether the same mechanisms will be relevant for understanding more complex decisions.</span></span></p><p class="MsoNormal" style="margin-right:-9.0pt"><span style="font-family:Arial"><span style="mso-tab-count:1"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">As a first step towards extending our understanding of decision-making, we examined behavior, physiology and the effects of microstimulation on a 2- and 4-choice decision task. We observed differences in monkeys’ speed and accuracy on the 2- and 4-choice tasks and considered two hypotheses about the neural mechanism underlying the differences.</span><span style="mso-spacerun: yes"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">First, we asked whether behavioral differences were due to changes in the conversion of sensory inputs from the middle temporal area (MT) into evidence in LIP. We found that changes in motion strength had the same effect on the build up of firing rate in LIP for the 2- and 4-choice tasks.</span><span style="mso-spacerun: yes"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">Further, microstimulation in MT biased the monkeys’ choices similarly on the 2- and 4-choice tasks. Taken together, these observations suggest that the conversion of sensory inputs into evidence was similar on the 2- and 4-choice tasks.</span><span style="mso-spacerun: yes"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">Next, we asked whether behavioral differences were due to changes in the monkeys’ threshold for making a choice.</span><span style="mso-spacerun: yes"><span class="Apple-style-span" style="font-weight: normal;"> </span></span><span class="Apple-style-span" style="font-weight: normal;">Interestingly, the rules for terminating decisions appeared to be rather different on the 2 and 4-choice tasks. Specifically, evidence accumulation began at a lower firing rate for the 4-choice task, but reached a common level at the end of the decision process. The larger firing rate excursion suggests that decision-making mechanisms required more evidence before committing to a choice. Importantly, these changes appear to explain differences in speed and accuracy on the two tasks. The physiological adjustments constitute an effective strategy for handling increased difficulty on the 4-choice task. </span><o:p></o:p></span></p><p class="MsoNormal" style="margin-right:-9.0pt"><span style="font-family:Arial"><o:p> _________________________________________________________________________________________________________________<br></o:p></span></p> <!--EndFragment--> </b></span></font></div>Anirvan Ghosh</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Chair, Neurobiology Section, MC0366</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">Director, Neurosciences Graduate Program</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">University of California San Diego</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">La Jolla, CA 92093-0366</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; font: normal normal normal 12px/normal Helvetica; min-height: 14px; "><br></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">858-822-4142 (ph)</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; ">858-822-4144 (FAX)</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" style="font: normal normal normal 12px/normal Helvetica; "><a href="http://www.ghoshlab.org">http://www.ghoshlab.org</a></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><br></div></span></div></span><br class="Apple-interchange-newline"> </div><br></div></blockquote></div><br><div apple-content-edited="true"> <span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="font-size: 12px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>---------------------------------------------------------</div><div>Angela J. Yu</div><div>Assistant Professor</div><div>Department of Cognitive Science</div><div>UCSD, Mail Code 0515</div><div>9500 Gilman Drive</div><div><div>La Jolla, CA 92093-0515</div></div><div><br></div><div>Email: <a href="mailto:ajyu@cogsci.ucsd.edu">ajyu@cogsci.ucsd.edu</a></div><div>Phone: 858-822-3317</div><div>Fax: 858-534-1128</div><div>Website: <a href="http://www.cogsci.ucsd.edu/~ajyu">www.cogsci.ucsd.edu/~ajyu</a></div><div>---------------------------------------------------------</div></div></div></div></span></div></div></div></span> </div><br></body></html>