School of Biological Sciences
Reg. No. 200604393R
Research Theme: Neurobiology
Research Project Title: Mediation of Reproductive Investment by Vasopressin
Testosterone Synergy
Principal Investigator/Supervisor: Asst/Prof Ajai Vyas
Co-supervisor/ Collaborator(s) (if any): NA
Project Description
Please note that Ethoneuro lab values intellectual fit between existing team members and new
people. Also, students are expected to take part in intellectual work of planning experiments.
In John Gardner’s wonderful fiction ‘Grendel’, a wise protagonist sums up the nature of life
with two terse axioms. “Everything fades; and, alternatives exclude”. These axioms poignantly
capture the essence of animal life histories (i.e. schedule and duration of key events in an
organism’s lifespan like reproduction and death). For each morsel of food regurgitated by
parents for the brood, there is one less morsel available to the parents for their survival. For
each decision to create bright plumage there is risk that predators also will be attracted by this
sexual advertisement. In short, current fitness cannot be maximized without forgoing future
fitness and survival. Alternatives of “me-now” and “me-later” exclude each other. Animals
typically negotiate these trade-offs using conditional behaviors, or ‘if-then-else’ clauses.
How animals execute these conditional programs? Reproduction requires presence of
opportunities (e.g. presence of sexually receptive females). It also requires metabolic
wherewithal, so that cost and competition during partaking of these opportunities can be
sustained. How do animals integrate these factors? How do biological substrates mediate the
shift of behavior from survival to reproduction or vice versa (i.e. trade-off between “me-now”
and “me-later”)? These are broad questions for this project.
Testosterone is required for male sexual advertisement and reproductive behaviors. And yet,
production of testosterone is costly for an organism because of its metabolic costs and
opportunity costs. So individuals must increase testosterone when, and only when, current
reproductive benefits reaped by it (proverbial “me-now”) are greater than costs imposed by it
in terms of future survival/reproduction (“me-later”). In this proposal, we aim to dissect brainhormone interactions required for this conditional increase in the testosterone and
reproductive behaviors. Medial amygdala (MeA) is a brain region that integrates information
about sexual opportunities (e.g. presence of females) and hormonal status of the male (i.e.
levels of testosterone). This is achieved by molecular interaction of testosterone with arginine
vasopressin neurons and anatomical projections of AVP neurons to brain regions involved in
motivation. In this backdrop, we will study 1) Functional reciprocity between MeA-AVP and
gonadal testosterone; 2) The ability of this loop to change behavior according to incipient
reproductive opportunities; and, 3) Neuroendocrine pathways connecting MeA-AVP with
gonadal testosterone.
School of Biological Sciences
Reg. No. 200604393R
Supervisor contact:
If you have questions regarding this project, please email the Principal Investigator:
[email protected]
SBS contact and how to apply:
Associate Chair-Biological Sciences (Graduate Studies) :[email protected]
Please apply at the following: http://admissions.ntu.edu.sg/graduate/R-Programs/RWhenYouApply/Pages/R-ApplyOnline.aspx
60 Nanyang Drive, Singapore 637551
Tel: +65 6316 2800, Fax: +65 6791 3856
Website: http://www.sbs.ntu.edu.sg/Pages/Home.aspx