Christie Sahley - US grants

The goal of this research is to elucidate the synaptic basis of associative learning. Experiments with vertebrates have shown the essential conditions for stimuli to become associated are: 1) stimuli (CS and US) must occur together in time, and 2) the CS must predict the occurrence of the US. Experiments with invertebrates have shown them to be favorable preparations in which to examine the cellular basis of simple forms of learning such as habituation and sensitization. The aim of the proposed experiments is to use an invertebrate, Limax maximus, to explore the cellular basis of associative learning more characteristic of vertebrates. Behavioral experiments with Limax demonstrate that associative learning in Limax is similar to that observed in vertebrates. That is, food odors can be made aversive following odor-quinine pairings and non-food odors can be made attractive following odor-fructose pairings. Further, the learned association is dependent both on the stimuli occurring in time and the degree to which the CS predicts the US. In addition, the learning both affects the odor-dependent locomotion and modulates feeding. Experiments have shown that a semi-intact preparation is capable of learning using procedures similar to those used with intact animals: pairing of a food taste which normally elicits feeding with a bitter taste results in a selective suppression of feeding only to the taste paired with the US. Also, several feeding motoneurons and a modulatory interneuron have been identified. The goals of this proposal are threefold: Using combinations of anatomical, behavioral, and physiological techniques 1) to identify 'command' and 'convergence' interneurons of the feeding circuit; 2) to analyze the role of olfactory input on feeding; and 3) to characterize the cellular basis of the temporal specificity and predictability underlying the odor-taste associations demonstrated in the intact animal.

The long term goal of this project is to understand basic mechanisms of associative learning. Associative learning is the way in which causal relationships are extracted from the environment and is of great adaptive significance since it allows animals to modify their behavior on the basis of learned associations between cues and consequences. Two variables are important in associative learning: the close temporal association, or contiguity of the stimuli, and the reliability with which the first stimulus predicts the occurrence of the second. Although many neural correlates of contiguity have been described, no consensus yet exists as to the mechanism of associative learning. In particular, very little is known regarding the cellular basis of predictability. The work proposed here will use behavioral, cellular, pharmacological and biophysical techniques to investigate mechanisms of the associative process, with a special emphasis on predictability. The medicinal leech, Hirudo medicinalis is a favorable animal for such studies; its stereotyped, reiterated nervous system has permitted a detailed mapping of sensory and motor pathways at the level of single, identified cells. Leeches can be taught to associate a light touch (CS) with a shock (US). Several cells in the neural pathways mediating these stimuli have been identified and potential sites of convergence between the two have been found. The neurotransmitter serotonin and the peptide proctolin are implicated in the increased excitability correlated with learning and will be pursued further in the proposed experiments. Anatomical experiments will be conducted to identify the source of these compounds and the ionic basis of the increased excitability will be determined. Two specific hypotheses will be tested: 1) these compounds modulate background potassium (K+) channels, important determinants of a cell's excitable properties and 2) second messengers will mediate the channel modulation. Cell killing and 5HT depletion techniques will be used to determine the causal relationship of particular cells or transmitter systems to associative learning. Many fundamental cellular mechanisms were established before invertebrates and vertebrates diverged, and it is reasonable to expect that a process as basic as learning will show strong parallels in the two groups. Thus with an understanding of the basic behavioral and cellular mechanisms of learning, better therapies and pharmacological interventions can be developed which would be useful for the treatment of mental retardation and in the amelioration of the memory deficits often seen in aging.

Burrell, Brian
0213458

Sensitization is a simple form of learning in which an animal's responses to environmental stimuli are enhanced. This form of behavioral plasticity is important because it contributes to processes of attention and arousal, as well as to more complex forms of learning such as classical (i.e. Pavlovian) conditioning. Typically, sensitization is induced by the delivery of a particularly strong or salient stimulus. This stimulus activates neurons that release modulatory neurotranmitters, which alter the neural circuit mediating the test behavior. Because the modulatory neurons are distinct from the neurons that mediate the test behavior, this process is referred to as extrinsic sensitization. However, there are many examples where sensitization is induced by a stimulus that is similar or identical to the stimulus that elicits the test behavior. In such situations, modulatory neurotransmitters are released by neurons within the circuit that mediates the test behavior. This is referred to as intrinsic or wind-up sensitization.
Using the medicinal leech, the distinct physiological and cellular mechanisms of intrinsic and extrinsic sensitization will be examined. These experiments will combine electrophysiological recordings from single neurons with simultaneous monitoring of sensitization-induced changes in a defensive withdrawal reflex (shortening). Both forms of sensitization are observed in the leech shortening reflex and the leech nervous system is extremely well characterized, making it possible to record from single, identifiable neurons that are known to mediate this behavior.

Intellectual Merit: This CSEMS program builds on an existing proven and successful cross-school CSEMS program. The program is making a positive impact on on-time graduations by permitting full time enrollments; having a marked effect on reducing students' loan indebtedness; broadening students' educational experiences within their discipline by involving all the students in one-on-one mentoring with faculty in the student's major (many involving research experiences) and outside their major by involving the students with faculty and staff who participate in enhancement programs designed specifically for the scholarship holders. The Program also works to ensure the continuing academic success of the students by expanding and enhancing long-term, well developed, institutional student support infrastructure in the participating schools.

Broader Impact: The participating schools have large numbers of students who fit the CSEMS eligibility criteria. A careful nomination and selection procedure is used to ensure that program goals are met. In addition to long established in-place campus support programs, scholarship recipients also have a faculty mentor in their major, and this may include a mentored research experience. In addition there are activities offered that focus on graduate school and employment opportunities in the high technology sector. The established Purdue University CSEMS Program Web Site and the use of E-mail ensure that there is good communication between the students and staff.

The Purdue Center for Faculty Success (PCFS) will provide targeted research, programs and University-level coordination to increase the number of minority women in science, technology, engineering, and mathematics (STEM) faculty positions; improve the success of all women STEM faculty; and engage all faculty in transforming the institution. The PCFS will combine NSF and institutional support to undertake research on the applicability of specific theoretical models in the Purdue environment, develop programs informed by these theoretical models and that focus on gaps in our current portfolio of initiatives, and provide formative assessment and comprehensive evaluation of programmatic impacts. University leaders and policymakers, including Purdue President and ADVANCE PI France Córdova, will use PCFS results as compelling evidence to sustain and advance institutional transformation and implement policy that will impact the Purdue STEM community and beyond. Our vision is to accelerate institutional transformation through a highly visible infrastructure that offers innovative campus-wide coordination and collaboration for initiatives such as: an innovative and prestigious Presidential ADVANCE Advocate position focused on increasing the diversity of the pool of STEM faculty candidates; enhancing the role of Purdue's ethnic cultural centers in faculty support; adapting ADVANCE best practice STRIDE and WISELI "train the trainer" workshops; mentoring cohorts of junior faculty for research and career development; providing leadership mentoring for associate and full professors; transforming the entire faculty, including majority faculty; developing Diversity Forum toolkits; and initiating Diversity Catalyst and Leader Workshops.

Intellectual Merits. Institutional ethnography is a critical method with which to approach understanding the experience of marginalized participants, and provides a new approach to enrich ADVANCE research on STEM women faculty, in particular underrepresented minority women. PCFS efforts will not only advance understanding of the applicability of pipeline and chilly climate models that ground so many "women in science" initiatives but will explore through institutional ethnography the applicability of proposed new models that integrate "boundary" metaphor approaches for exploring women's underrepresentation. Thus PCFS research will generate new knowledge and advance theoretical frameworks that will be of interest to theorists and ADVANCE programs across the nation. The Purdue ADVANCE Advocate and cultural center efforts aimed at enhancing minority women STEM faculty recruiting will be assessed for new insights into enhancing minority faculty recruitment.

Broader Impacts. Improved understanding of the career pathways of women STEM faculty at Purdue, in combination with the assessments of the effectiveness of novel programs, will result in a rigorously tested, explicitly articulated suite of programs that other institutions can adapt to their own campuses. Innovative PCFS efforts to recruit minority women STEM faculty will help address a particularly persistent national STEM challenge, and other PCFS initiatives will increase participation of women in the STEM faculty ranks and in leadership positions. This will have an immediate positive impact on STEM undergraduate and graduate women at Purdue who may contemplate a potential career in academia and potentially on all individuals who are interested in science and engineering careers. PCFS includes Research Team students at the graduate and post-doctoral level and junior faculty in all programmatic initiatives and thus will support and encourage early-career advancement. Through novel partnerships with our ethnic cultural centers, PCFS will broaden participation across campus in the recruitment and support of faculty from underrepresented groups. The transformation of the entire faculty, including majority faculty, by PCFS will provide new approaches to sustain institutional support for faculty success. In addition to publications in leading journals and presentations at national and international research conferences, Purdue will disseminate a PCFS-developed toolkit for Diversity Forums and will host a national conference focused on ADVANCE theoretical frameworks as drivers for institutional change.

This project involves the Purdue University Colleges of Science, Education, Engineering and Technology in a partnership with Crawfordsville, Logansport, and Benton County schools, all small town and rural districts. Up to 35 science, technology, engineering or mathematics (STEM) majors are being helped by this Noyce project in their efforts to become high school science and mathematics teachers. Support is provided through scholarships (some with one year of aid and others with two years of aid, reflecting the years remaining to the student's degree when the scholarships are first awarded) and through a program designed for them in cooperation with other existing and emerging programs for STEM teacher workforce development at Purdue. The Purdue Center for Research and Engagement in Science and Mathematics Education (CRESME), a joint effort between the Colleges of Science and Education, is taking the lead in this effort, aided by other educational research units on the Purdue campus, including the Colleges of Technology and Engineering, and the Discovery Learning Center. The program is improving STEM education within small, rural school districts around Purdue and is providing insights that may be extended to similar rural settings around the nation.

Intellectual Merit: Educational research-oriented centers and departments on campus are working with teacher preparation and new teacher support programs and the Noyce project to recruit talented STEM undergraduates to teaching careers. They are working with the students, helping them explore the educational issues in their technical fields while at Purdue, especially in rural communities, and supporting them programmatically during their initial teaching years. The Noyce Scholars are being housed intellectually within CRESME. which is responsible for project infrastructure, curricula and course design, and for tracking of the scholars in order to determine project outcomes. As part of their teacher preparation program Noyce Scholars are participating in senior thesis projects (conducting research as assistants in existing STEM education research efforts in their disciplines) and a special Noyce seminar course. They are also being provided with a network of support and mentoring both while they are at Purdue and after they begin their teaching careers.

Broader Impacts: Through dissemination of lessons learned from this project, Purdue is improving its ability to provide STEM teachers with education services and is providing direct outreach assistance to the increasingly diverse underserved rural and small town communities of Indiana and educational models for use throughout Indiana and the nation.

The CIC Alliance for Graduate Education and the Professoriate's Professional Advancement Initiative (PAI) was created in response to the NSF's Alliances for Graduate Education and the Professoriate (AGEP) program solicitation (NSF 12-554) for the AGEP-Transformation (AGEP-T) track. The AGEP-T track targets strategic alliances of institutions and organizations to develop, implement, and study innovative evidence-based models and standards for STEM graduate education, postdoctoral training, and academic STEM career preparation that eliminate or mitigate negative factors and promote positive practices for URMs.

The CIC AGEP PAI is a collaboration between the University of Illinois-Champaign (UIUC) and Purdue University (PU) to partner with other university members of the Committee on Institutional Cooperation (CIC): Indiana University, University of Iowa, University of Michigan, Michigan State University, University of Minnesota, University of Nebraska-Lincoln, Northwestern University, Ohio State University, Pennsylvania State University, and University of Wisconsin-Madison.

The Alliance is creating a "Professorial Advancement Initiativ" (PAI) with a goal to increase the number of underrepresented minority (URM) faculty members hired within the CIC partnering institutions. The PAI Alliance participants are URM U.S. citizen in STEM fields. The two objectives for this project are:
Objective 1: To create a pool of URM post-doctoral fellows, prepared and trained to enter the academy as tenure track facility.
Objective 2: To educate faculty and faculty search committees about unconscious bias and diversity hiring.

The objectives have the following measureable outcomes associated with them:
1. The number of URM postdocs recruited into the PAI.
2. The number of PAI applications submitted to the CIC partnering institutions.
3. The number of URM postdocs interviewed with the CIC partnering institutions.
4. The number of offers extended to URMs in the CIC partnering institutions.
5. The number of offers accepted.
6. The number of faculty mentors recruited to participate in the PAI.
7. The number of faculty members participating in PAI hiring committee training program.

The activities that contribute to the model for the CIC's AGEP PAI include implementing:
- A program of small group mentoring for URM postdoctoral fellows across STEM disciplines in the CIC partnering institutions;
- Interactive video-teleconferences for mentors and protégés (aka, the postdoctoral fellows); and
- A program for training faculty and hiring committees.

The proposal includes a social science research study focusing on determining how the mentoring environment, ranging from a micro-systems (e.g., peer-to-peer interactions, faculty-to-peer interactions) to macro-systems (e.g., broader social context), affects the self-efficacy and identity of postdoctoral fellows within their STEM disciplines. Specifically, the team is exploring answers to two primary questions that address the research goal of this project:
1. What is the influence of mentoring on URM postdoctoral fellows' self-efficacy and identities as STEM researchers?
2. How does the degree of importance that STEM postdoctoral fellows place on having a matched mentor background influence their self-efficacy and identities?
A third question explores the impacts of faculty bias on postdoctoral fellows: What is the influence of mentoring experience on faculty's subtle bias towards URM postdoctoral fellows' in STEM disciplines?