Dr. Richard Bertram

Research Interest

• Mathematical and Computational Neuroscience
• Mathematical Physiology
• Dynamical Systems

Current Research Interests

Activity of Pancreatic Beta-Cells

Pancreatic Beta-cells are the only cells in the body that secrete insulin, a hormone that is necessary for the uptake of glucose by other cells. Defects in beta-cell functioning lead to diabetes, which can result in death if not treated. The release of insulin is controlled by many physiological variables, including the cell's electrical activity, calcium, and nucleotide concentrations. I work in the development and analysis of mathematical models of beta-cell activity. This work is done in collaboration with Artie Sherman at the National Institutes of Health and Les Satin at the University of Michigan Medical School.

Hypothalamic Control of Hormone Secretion

The hypothalamus is the region of the brain that regulates the level and timing of hormone release from endocrine glands. One such gland, the pituitary, is located near the hypothalamus, and secretions from this gland regulate secretions from other glands. For this reason, the pituitary is sometimes called the "master gland". The hypothalamus sends both stimulatory and inhibitory input to the pituitary, resulting in neural regulation of secretion from gonadotrophs, somatotrophs, corticotrophs, melanotrophs, and lactotrophs. I collaborate with Marc Freeman, Joel Tabak, Arturo Gonzalez-Iglesias, and Maurizio Tomaiuolo (all at FSU) in the development and testing of mathematical models to help understand the complex cellular and network interactions involved in the secretion of prolactin from pituitary lactotrophs. Prolactin has many roles in the body, including milk production in the mammary gland.

Bursting Oscillations in Excitable Cells

In nerve cells, information is transmitted through electrical impulses. Electrical impulses also cause muscles to contract and endocrine cells to secrete hormones. Quite often, impulses are generated as high-frequency bursts, followed by periods of quiescence. This is particularly true in endocrine cells such as pancreatic beta-cells. I am interested both in the dynamics of bursting (a mathematical topic) and in the mechanisms by which different cells generate periodic bursts of impulses (a biological topic).

Synaptic Transmitter Release and Short-Term Plasticity

Information is processed and transmitted in nerve cells by electrical impulses. These impulses are passed from one nerve cell to the next through a process called synaptic transmission. In the presynaptic cell, an impulse evokes the release of one or more chemical neurotransmitters. These transmitters diffuse to the postsynaptic cell and bind to transmitter receptors, resulting in a postsynaptic voltage change. I am working on the development of mathematical models that describe certain aspects of this process, incorporating much of the known biophysical data. The goal is to better understand transmitter release and the mechanisms behind the enhancement or depression of release, i.e., synaptic plasticity. My most recent work is done in collaboration with done in collaboration with Artie Sherman and Victor Matveev.

Neural Network Controlling Bird Songs

This is my most recent project, done in collaboration with Frank Johnson, and Wei Wu. Song birds have a dedicated region of the brain to produce stereotyped songs. The Johnson lab is studying how this region of the brain controls vocalization in zebra finches. I work with Johnson and Wu to quantify the experimental data and, in the future, to develop models of the neural network controlling song production.

Publications

• Matveev V, Bertram R, Sherman A. Ca2+ current versus Ca2+ channel cooperativity of exocytosis. J Neurosci. 29(39):12196-20. (2009)
• Fendler B, Zhang M, Satin L, Bertram R. Synchronization of pancreatic islet oscillations by intrapancreatic ganglia: a modeling study. Biophys J. 97(3):722-9. (2009)
• Bertram R, Kolb M, Hillen W. In vivo activation of tetracycline repressor by Cre/lox-mediated gene assembly. J Mol Microbiol Biotechnol. 17(3):136-45. (2009)
• Bertram R, Kolb M, Hillen W. In vivo activation of tetracycline repressor by Cre/lox-mediated gene assembly. J Mol Microbiol Biotechnol. 17(3):136-45. (2009)
• Kuperman V, Schreuder R, Bertram R, Baayen RH. Reading polymorphemic Dutch compounds: toward a multiple route model of lexical processing. J Exp Psychol Hum Percept Perform. 35(3):876-95. (2009)
• Resch M, Roth HM, Kottmair M, Sevvana M, Bertram R, Titgemeyer F, Muller YA. Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of YvoA from Bacillus subtilis. Acta Crystallogr Sect F Struct Biol Cryst Commun. 65(Pt 4):410-4. (2009)
• Helena CV, McKee DT, Bertram R, Walker AM, Freeman ME. The rhythmic secretion of mating-induced prolactin secretion is controlled by prolactin acting centrally. Endocrinology. 150(7):3245-51. (2009)
• [?], Bertram R, [?], Niemi P. Development of the letter identity span in reading: evidence from the eye movement moving window paradigm. J Exp Child Psychol. 102(2):167-81. (2009)
• Tomaiuolo M, Bertram R, Houle D. Enzyme isoforms may increase phenotypic robustness. Evolution. 62(11):2884-93. (2008)
• Zhang M, Fendler B, Peercy B, Goel P, Bertram R, Sherman A, Satin L. Long lasting synchronization of calcium oscillations by cholinergic stimulation in isolated pancreatic islets. Biophys J. 95(10):4676-88. (2008)
• Bertram R, Li YX. A mathematical model for the actions of activin, inhibin, and follistatin on pituitary gonadotrophs. Bull Math Biol. 70(8):2211-28. (2008)
• Wu W, Thompson JA, Bertram R, Johnson F. A statistical method for quantifying songbird phonology and syntax. J Neurosci Methods. 174(1):147-54. (2008)
• Bertram R, Rhoads J, Cimbora WP. A phantom bursting mechanism for episodic bursting. Bull Math Biol. 70(7):1979-93. (2008)
• White SJ, Bertram R, [?] J. Semantic processing of previews within compound words. J Exp Psychol Learn Mem Cogn. 34(4):988-93. (2008)
• Bertram R, Arceo RC 2nd. A mathematical study of the differential effects of two SERCA isoforms on Ca2+ oscillations in pancreatic islets. Bull Math Biol. 70(5):1251-71. (2008)
• Leibig M, Krismer B, Kolb M, Friede A, [?], Bertram R. Marker removal in staphylococci via Cre recombinase and different lox sites. Appl Environ Microbiol. 74(5):1316-23. (2008)
• Achuthan S, Asbury T, Hu J, Bertram R, Cross TA, Quine JR. Continuity conditions and torsion angles from ssNMR orientational restraints. J Magn Reson. 191(1):24-30. (2008)
• Toporikova N, Tabak J, Freeman ME, Bertram R. A-type K(+) current can act as a trigger for bursting in the absence of a slow variable. Neural Comput. 20(2):436-51. (2008)
• Thompson JA, Wu W, Bertram R, Johnson F. Auditory-dependent vocal recovery in adult male zebra finches is facilitated by lesion of a forebrain pathway that includes the basal ganglia. J Neurosci. 27:12308-20. (2007)
• Bertram RM, Takemoto JK, Remsberg CM, Vega-Villa KR, Sablani S, Davies NM. High-performance liquid chromatographic analysis: applications to nutraceutical content and urinary disposition of oxyresveratrol in rats. Biomed Chromatogr. . ()