Associate Professor of Biology F. W. Olin Science Center, Room 2375 1250 N. Dartmouth Ave. Claremont, CA 91711 (909) 607-9122 aahn@hmc.edu

Click here to see a highlight of our most recent work on the variability of calf muscle size and the heel of one's foot!

Education & Professional Experience

• B.A., Integrative Biology, University of California, Berkeley
• Ph.D., Integrative Biology, University of California, Berkeley
• Postdoctoral Research Fellow, Harvard University
• Visiting Scientist, Massachusetts Institute of Technology
• Visiting Assistant Professor, Harvey Mudd College
• Assistant Professor of Biology, Harvey Mudd College

Teaching

• Bio 54: Biology Laboratory
• Bio 81/82: Human Physiology & Disease
• Bio 101: Comparative Physiology
• Bio 103: Physiology Laboratory
• Bio 183: Topics in Physiology (seminar)
• Bio/Eng 190B: Biomechanics

Desert Iguana, Dipsosaurus dorsalis.        See more lizard, frog, and toad pictures!

Research Interests

Professor Ahn’s research focuses on the neural control and mechanics of animal locomotion. We take an integrative and multi-disciplinary approach to examine the different levels of organization that influence the behavioral output of the neuro-musculo-skeletal system in animals such as frogs, lizards, tarantulas, and even humans! Our work includes examining the neural signals sent to muscles and how the different levels of musculo-skeletal organization respond to these neural signals. By spanning the fields of muscle physiology, biomechanics, and motor control, we hope to discover general principles underlying the neuro-mechanical basis of legged locomotion.

Senior Theses

Shireena Desai ’05: Force-length properties of fast- and slow-twitch muscle under varying stimulation levels in the Desert Iguana (Dipsosaurus dorsalis).

Jae Shin ’05: Conservation of neural control in Anurans during swimming at different speeds.

Alejo Enriquez ’06: Energetic differences between bipedal and quadrupedal locomotion in Dipsosaurus dorsalis.

Trisha Staab ’06: In vivo activity of the iliofibularis muscle during two-legged and four-legged running in the Desert Iguana.

Lauren LaCount '07: Velocity, acceleration, and cost of activity of bipedal and quadrupedal locomotion in the desert iguana, Dipsosaurus dorsalis

Karla Whitfileld '10:  Thermal sensitivity of locomotory performance in the tarantula, Aphonopelm hentzi. (co-advised with Adolph)

Nick Booster '11 (Pitzer):  Effect of temperature on walking kinematics in tarantulas.  (co-advised with Adolph) 

Rebecca Salzman '12 (CMC):  Effect of active and passive components on the kinematics of an intact frog ankle.  

Christopher Jerry '12 (CMC):  The neural control and kinematics of walking in humans.

Lab Members 2012

Charlie Brayton '13 (Chem-Bio)
Tania Bhatia '13 (Scripps)
Parker Martin '13 (Engineering)
Rachel Roley '15 (Engineering)
Jennie Tave '12 (Scripps)

Selected Publications

Ahn AN. in press. How muscle function - the work loop technique. J. Exp. Biol. 

Ahn AN, Kang JK*, Quitt MA*, Davidson BD*, Nguyen CT*.  2011.  Variability of neural activation during walking in humans:  Short heels and big calves.  Biol. Lett.  doi:10.1098/rsbl.2010.1169 [article]

Wu GC*, Wright JC, Whitaker DL & Ahn AN. 2010. Kinematic evidence for superfast locomotory muscle in two species of teneriffiid mites. J. Exp. Biol. 213: 2551-2556. [article]

Nishikawa K, Biewener A, Aerts P, Ahn A et al. 2007.  Neuromechanics: An integrative approach for understand motor control. Integr. Comp. Biol. 47: 16-54. [article]

Ahn AN, Meijer K & Full RJ. 2006. In situ muscle power differs without varying in vitro mechanical properties in two insect leg muscles innervated by the same motor neuron. J. Exp. Biol. 209: 3370-3382. [article]

Biewener AA & Ahn AN. 2006. Tired of fatigue? Factors affecting the force-length relationship of muscle. J. Appl. Physiol. 101: 5-6. [article]

Ahn AN, Furrow E* & Biewener AA. 2004. Walking and running in the red-legged running frog, Kassina maculata. J. Exp. Biol. 207: 399-410. [article]

Ahn AN, Monti RJ & Biewener AA. 2003. In vivo and in vitro heterogeneity of segment length changes in the semimembranosus muscle of the toad. J. Physiol. 549: 877-888. [article]

Ahn AN & Full RJ. 2002. A motor and a brake: two leg extensor muscles acting at the same joint manage energy differently in a running insect. J. Exp. Biol. 205: 379-389. [article]

Full RJ, Stokes DR, Ahn AN & Josephson RK. 1998. Energy absorption during running by leg muscles in a cockroach. J. Exp. Biol. 201: 997-1012. [abstract | article (pdf)]

Full RJ & Ahn AN. 1995. Static forces and moments generated in the insect leg -- comparison of a 3-dimensional musculoskeletal computer-model with experimental measurements. J. Exp. Biol. 198: 1285-1298. [abstract | article (pdf)]

Weinstein RB, Full RJ & Ahn AN. 1994. Moderate dehydration decreases locomotor performance of the ghost crab, Ocypode quadrata. Physiol. Zool. 67: 873-891.

* undergraduate author