Sarah Ann Heimovics

Advisor: Lauren Riters

Contact Information:
Department of Zoology
356 Birge Hall
430 Lincoln Dr.
Madison, WI 53706
(608) 262-5410
email: saheimovics@wisc.edu

Dissertation Research: Breeding context-dependent neural regulation of singing behavior in male European starlings (Sturnus vulgaris)

Introduction
The proximate mechanisms regulating vocal behavior have been explored in several species and the neural circuitry involved in vocal signal learning, production, and perception has been identified in some model systems. However, what motivates an animal to communicate can be strongly influenced by social and environmental factors and often vocal behavior must be adjusted so that it occurs in response to socially relevant stimuli. How the rest of the brain interacts with vocal production circuits to ensure that vocal communication occurs in the appropriate context is not yet clear.

For my dissertation research, I use male European starlings as a model to explore the context-dependent regulation of vocal communication. Male starlings produce song throughout the year, but what motivates singing behavior depends on the context in which it occurs. In a non-breeding context, male and female starlings feed and roost in large, mixed-sex flocks. At this time male vocal behavior appears to play no direct role in mate attraction, but rather is thought to be important for flock cohesion and establishing/maintaining social hierarchies within the flock. Thus, vocal communication in a non-breeding context appears to be group motivated. In contrast, breeding context song plays a critical role in mate attraction. Once a male acquires a mate, song is restricted to periods immediately prior to copulation. Thus, in contrast with non-breeding context vocal behavior, singing behavior that occurs in a breeding context is sexually motivated, goal-directed, and often associated with immediate, external reinforcement (i.e. copulation).

The neural control of context-appropriate singing behavior likely involves interactions between brain regions regulating song production (i.e. the avian song control system) and brain regions regulating social behavior (i.e. the ‘social behavior network'). Many social behavior brain regions are components of either the mesolimbic or incertohypothalamic dopamine systems implicated in motivation and reward. Some of these regions have also been implicated in the neural control of song production. Social behavior and song control nuclei are dopaminergic, containing DA receptors and/or proteins associated with DA synthesis. Given that DA modulates highly motivated, goal-directed behaviors, my dissertation research tests the hypothesis that dopaminergic neurotransmission occurring within and between song control and social behavior brain regions differentially modulates male starling goal-directed and group motivated song.

Chapter I: Immediate Early Gene Immunocytochemistry
To identify what social behavior and song control regions may be involved in the context-dependent regulation of male starling song, I used immunocytochemistry for the protein products of immediate early genes (IEGs; cFos and ZENK) to ask if the relationship between song and brain activity differed between contexts. I measured numbers of IEG-labeled cells in 3 song control and 8 social behavior brain regions in the brains of males singing in either a goal-directed or a group motivated context. Correlation analyses revealed significant linear relationships between vocal behavior and neuronal activity in all of the brain regions examined except 2 (1 song control and 1 social behavior) and activity in only one brain region related to song in both motivational contexts. In most others, disparate trends for goal-directed and group motivated song were observed. Taken together, these data show that the neural control of singing behavior involves interaction between song control and social behavior nuclei and that there are fundamental differences in how these brain regions regulate breeding and non-breeding context song. Furthermore, they suggest that at least partially dissociable neural circuits modulate goal-directed and group motivated vocal communication in songbirds.

Chapter II: TH and DARPP-32 Immunocytochemisty
To gain insight into whether dopaminergic neurotransmission underlies these fundamental differences I used immunocytochemistry for TH (the rate-limiting enzyme in DA synthesis) and DARPP-32 (a DA D1 receptor-associated protein) to ask if the relationship between song production and proteins associated with either DA synthesis or DA receptor binding in song control and social behavior regions differed between a goal-directed and a group motivated context. Correlation analysis revealed significant linear relationships between markers of dopamine and song in both contexts. However, in none of the brain regions examined were the relationships similar for both breeding and non-breeding song. For example, in the ventral tegmental area, indices of TH correlated with only breeding context song whereas in the lateral septum indices of DARPP-32 correlated with only non-breeding context song. Taken together, these data suggest that dopamine acts in distinct neural circuits to regulate goal-directed versus group-motivated song21.

Chapter III: D1 and D2 Receptor Autoradiography
In collaboration with the Ball Lab at Johns Hopkins University, I performed receptor autoradiography for D1 and D2 dopamine receptors in breeding and non-breeding male starlings. Preliminary analyses show dense D1 and D2 receptors distinguish Area X from surrounding medial striatum. D1 and D2 receptors are also denser within the medial striatum, lateral striatum, and ventral tegmental area compared to surrounding regions. I am in the process of quantifying receptor density in song control and social behavior nuclei and will soon determine if context-dependent relationships between dopamine and song occur at the receptor level as well.

Chapter IV: pTH and cFOS/TH double-label Immunocytochemistry
The final chapter of my dissertation focuses on only sexually motivated singing behavior. I have performed and am in the process of quantifying a cFos/TH double label immunocytochemistry to determine if the breeding context-specific correlations between cFos and song highlighted in Chapter I are dopaminergic. I am also in the process of running an immunocytochemistry for the phosphorolated form of TH to see if the breeding context-specific correlations highlighted in Chapter II reflect active synthesis of DA.

Significance
Taken together, my dissertation shows that song produced in different motivational contexts has different underlying mechanisms and highlights dopamine as a potential modulator of context-appropriate vocal behavior in songbirds.

Publications

• (in preparation; anticipated submission: December 2007) “D1 and D2 dopamine receptor densities in male European starlings (Sturnus vulgaris) in different reproductive states”

• (in preparation; anticipated submission: September 2007) “Breeding context-dependent relationships between song and dopaminergic markers in song control and social behavior nuclei in male European starlings”

• Heimovics SA, Riters LV. “ZENK labeling within social behavior brain regions reveals breeding context-dependent patterns of neural activity associated with song in male European starlings (Sturnus vulgaris) (Behav Brain Res. 2007 Jan 25;176(2):333-43)

• Heimovics SA, Riters LV. “Breeding context-dependent relationships between song and cFOS labeling within social behavior brain regions in male European starlings (Sturnus vulgaris) (Horm Behav. 2006 Dec;50(5):726-35)

• Heimovics SA, Riters LV. “Immediate early gene activity in song control nuclei and brain areas regulating motivation relates positively to singing behavior during, but not outside of, a breeding context.” (J Neurobiol. 2005 Dec;65(3):207-24.)

Curriculum Vitae (pdf)

Current (June 2002-present)

• PhD student University of Wisconsin, Zoology Department
  • Dr. Lauren Riters’ Lab
• Dissertation title: Breeding context-dependent neural regulation of song production in male European starlings (Sturnus vulgaris)

Graduate Education 

• PhD program in Zoology, University of Wisconsin-Madison
• Academic Summary
• Neuroscience
• Endocrinology
• Animal Behavior
• Statistics
• Professional  Residency in Environmental Education (PREE) Program, Teton Science School (certification completed August 2001 credited through Utah State University)
• Academic Summary
• Ecology
• Education
• Teaching Practicum

Undergraduate Education

• Bachelor of Arts in Biology with honors; University of Kansas, Lawrence Kansas (2000)
  • Cumulative GPA: 3.68
• Major (Biology) GPA: 3.89

• John and Virginia Emlen Award to support research in the behavioral sciences (Spring 2006, UW-Madison)
• National Science Foundation Pre-Doctoral Fellowship (Spring 2003)
• John Jefferson Davis Travel Award (Fall 2004, 2005, 2006; UW-Madison)
• Leopold Award for Achievement in Field Science (Fall 2000; Teton Science School)
• Outstanding Research Presentation Award, Undergraduate Research Symposium (Spring 2000; University of Kansas)
• George Gould Undergraduate Research Award for Entomology (Fall 1999; University of Kansas)
• Undergraduate Research Award (Spring 1999; University of Kansas)
  

Publications

• (in preparation; anticipated submission: December 2007) “D1 and D2 dopamine receptor densities in male European starlings (Sturnus vulgaris) in different reproductive states”
• (in preparation; anticipated submission: September 2007) “Breeding context-dependent relationships between song and dopaminergic markers in song control and social behavior nuclei in male European starlings”
• Heimovics SA, Riters LV. “ZENK labeling within social behavior brain regions reveals breeding context-dependent patterns of neural activity associated with song in male European starlings (Sturnus vulgaris) (Behav Brain Res. 2007 Jan 25;176(2):333-43)
• Heimovics SA, Riters LV. “Breeding context-dependent relationships between song and cFOS labeling within social behavior brain regions in male European starlings (Sturnus vulgaris) (Horm Behav. 2006 Dec;50(5):726-35)
• Heimovics SA, Riters LV. “Immediate early gene activity in song control nuclei and brain areas regulating motivation relates positively to singing behavior during, but not outside of, a breeding context.” (J Neurobiol. 2005 Dec;65(3):207-24.)

Research Experience

• Dissertation research (June 2002-present)
  • Immunocytochemistry for immediate early genes (cFos/ZENK)  and proteins associated with dopamine (TH/DARPP-32)
  • Western Immunoblots
  • Catecholamine receptor autoradiography (D1, D2, and a-2)
  • Brain nuclei volume reconstruction
  • Testosterone enzyme assay
• Research Assistant, Monarch Watch, University of Kansas (August 2001-May 2002)
  • Distributed tagging supplies to citizen scientists
  • Maintained captive breeding colony
  • Compiled mark-recapture data on migratory Monarch butterflies
  • Traveled to over-wintering grounds in central Mexico to recover tags
• Research Assistant to Dr. Doug Wachob, Teton Science School (Summer 2000)
• Field technician at the Monitoring Avian Productivity and Survivorship (MAPS) bird banding station
• Assistant in coyote behavior research using radio telemetry
• Undergraduate Independent Study Research (1997-2000)
• "Heterozygosity and Mating Success in Monarch Butterflies"
• Examined the relationship between metabolic enzyme genotypes and male mating success
• Undergraduate Assistant to Dr. Orley “Chip” Taylor, University of Kansas (Summer 1998-2000)
• Supported research program in monarch navigation & orientation
• Visited grade schools to speak about ecology & conservation of Monarch butterflies

Teaching Experience

• Graduate Teaching Assistant for Zoology 102 (UW-Madison, Fall 2002; Fall 2006-present)
• Visiting lecturer-Univeristy of Wisconsin-Madison
• Zoology 603—Endocrinology (Fall 2004; 2 lectures)
  • Hormones and Mood
  • Hormones and Social Bonding
• Visiting lecturer-Beloit College
• Honor’s in Biology Seminar (Fall 2003)
• Professional Resident in Environmental Education (PREE) at the Teton Science School (See above.)
• 4 season field instructor; Combination of field, classroom, and outreach education; Designed and implemented science curriculum; Grades 1-12
• Undergraduate Teaching Assistant for Introductory Biology Labs (University of Kansas, Fall 1998-Fall 1999)

Meetings Attended/Presentations

• Poster presentation: Society for Behavioral Neuroendocrinology (Summer 2007)
• Abstract title: “Breeding context-dependent relationships between song and dopaminergic markers in song control and social behavior nuclei in male European starlings (Sturnus vulgaris)”
• Invited speaker: UW-Madison Department of Wildlife Ecology (Winter 2006)
• Presentation title: “Breeding context-dependent regulation of singing behavior in male European starlings (Sturnus vulgaris): Testosterone, neurotransmitters, and bird song.  Oh, my!”
• Poster presentation: Society for Neuroscience annual meeting (November 2005)
• Abstract title: “The effect of breeding condition on the relationships between song and the number of ZENK-labeled cells in regions within and outside of the song control system in male European starling”
• Invited speaker: UW-Whitewater department of biology undergraduate colloquium (Fall 2004)
• Presentation title: “Reproductive context and the neural regulation of singing behavior in European starlings (Sturnus vulgaris): Why the caged bird sings”
• Poster presentation: Society for Neuroscience annual meeting (October 2004)
• Abstract title:"Song relates positively to immediate early gene activity within the POM and VTA in spring, but not fall, in male European starlings”
• Meeting attended: Society for Neuroscience annual meeting (November 2003)

Back to Riters

Back to Grad Student List