1. Allison S. Shaw1,2,3, Dave Putz1, and S. Marc Breedlove1
The Effect of Fraternal Birth Order on Motor Coordination: Developing a Model for Autism, Attention Deficit/Hyperactivity Disorder, and Dyslexia
Allison S. Shaw1,2,3, Dave Putz1, and S. Marc Breedlove1
1 Neuroscience Program, Michigan State University, East Lansing, MI
2 College of Communication Arts and Sciences, Michigan State University, East Lansing, MI
3Ronald E. McNair Post-Baccalaureate Achievement Program/Summer Research Opportunity Program, Office of Supportive Services, Michigan State University, East Lansing, MI

2. Neurodevelopmental Disorders
Disorders that appears early in childhood
Most common are autism, dyslexia, and attention deficit/hyperactivity disorder
Suggested that they have a maternal antibody basis
Dalton et al. (2003) and Vincent et al.(2002) posit that these disorders may be caused by antibodies that transfer through the placenta to the fetus and affect development

3. Maternal Immune Transfer
This transfer has become known as the Maternal Immune Hypothesis and has been suggested as the cause for many other traits as well.

4. Fraternal Birth Order
Blanchard & Bogaert (1996) suggest that fraternal birth order may effect fetuses in utero by a similar maternal transfer
They posit that maternal immune response signals androgen release

5. Maternal Immune Hypothesis
Mother’s immune system
Fetal antigens
antibodies
androgen

6. Fraternal Birth Order Fraternal Birth Order
The birth order of male siblings born
Numerous human traits are related to fraternal birth order
Females overlooked
Females are not affected by fraternal birth order
Female birth order does not affect traits
Seem to be an additive affect

7. Fraternal Birth Order and Neurodevelopmental Disorders
Autism and Dyslexia have a fraternal birth order effect (Cohen-Baron, unpub. & Caspi, unpub.)
Males with Attention Deficit/Hyperactivity Disorder have been shown to be hypermasculinized in specific traits due to prenatal androgens, as suggested by the maternal immune hypothesis (McFadden, unpub.)

8. Motor Coordination Impaired motor coordination
Ranging from inability to control movement to deficiencies in fine motor movement
Static rod is a rodent paradigm used to assess motor coordination

9. This is the first study to control the birth order of mice in order to develop a model that will examine the etiology of Autism, Dyslexia, and Attention Deficit/Hyperactivity Disorder

10. Methodology Participants 110 mice 61 males 49 females
25 older brothers
36 older sisters
49 females
20 older brothers
29 older sisters
First litter fetuses were separated using Green Fluorescent Protein (GFP) transgene

11. Green Fluorescent Protein (GFP) transgenic mice

12. Green Fluorescent Protein (GFP) transgenic mice (cont’d)

13. Methodology (cont’d) Procedures 5 wooden dowel rods
Length: 69.5mm
Diameters: 31.1, 25.6, 19.5, 15.4, 9.4mm
Mice taken in groups of 10
All mice in group run on Rod 1 (31.1mm diameter)
Placed at end of rod facing away from ledge
Clock started when experimenter released mouse
Procedures were repeated for Rods 2-5.

14. Methodology (cont’d) Instrumentation Recorded into The Observer
Time to rotate 180
Time to reach line 10cm from ledge
If the mouse fell off, default time was given (180secs.)
Maximum time-180secs.

15. Results-Rotation Times
Effect F
Hypothesis df
Error df
Sig.
Weight
2.42 5
101
0.041
Older Siblings
1.24
0.296
Sex
0.22
0.959
Older Siblings * Sex
1.45
0.212
No significant effects of sex and older siblings on Static Rod rotation times

16. Results-Transit Times
Effect F
Hypothesis df
Error df
Sig.
Weight
0.76 5
101
0.583
Older Siblings
0.38
0.862
Sex
1.04
0.399
Older Siblings * Sex
2.02
0.082
There exists a small effect of sex and older sibling on Static Rod transit times

17. Transit Times as a Function of Sex and Older Siblings
seconds
seconds
seconds
seconds
seconds

18. Rod 1 *
seconds
*p< .056

19. Rod 4
seconds
**p< .034

20. Tentative Conclusions
Birth Order differentially affects motor coordination depending on sex
Females may not be affected by fraternal birth order, but instead by their male litter mates

21. Future Direction
Continue behavioral testing: object recognition and novelty, gap detection, social recognition, etc.
Modify model in order to better control for variability
Use male/female sets of twins to investigate androgen response

22. Acknowledgements Breedlove/Jordan Lab McNair/SROP staff
McNair/SROP Natural Science Methods Class
McNair/SROP colleagues
This research project was funded by NIH grant MH58703