Dr. James Angstadt
James D. Angstadt
B.S. Biology, Juniata College (1980)
Ph.D. Neuroscience, University of Wisconsin at Madison (1986)
Postdoctoral studies at Emory University and the University of Virginia (1986-1991).
Courses: Neurobiology, Writing and Research Skills for Biologists, and General Biology.
My primary teaching and research interests are in the field of neurobiology. In particular, my graduate and postdoctoral training focused on the neural control of rhythmic motor patterns, an important category of movements that includes such behaviors as walking, swimming, and breathing. I have chosen to study the cellular basis of these behaviors using invertebrates as model systems. Invertebrates offer many experimental advantages, including a relatively small number of neurons that are large and easily accessed for detailed physiological studies. Despite their relative simplicity, general principles of neuronal function emerge from studies of invertebrate nervous systems, principles that apply to more complex organisms, including humans.
Since 1986, I have been using the medicinal leech (Hirudo medicinalis) to explore questions related to motor behavior. At Siena College, my students and I first completed a study of the ionic basis of an unusual form of rhythmic electrical activity induced by pharmacological treatments of neurons in the intact ganglion. This activity takes the form of prolonged and synchronized oscillations that are similar in some respects to epileptic seizures that occur in humans and other vertebrate species. We traced the excitatory phase of this rhythmic activity to a persistent voltage-dependent sodium current. Similar currents are found in other rhythmic cells of the leech as well as in a variety of vertebrate neurons. In addition to helping support prolonged impulse bursts during rhythmic electrical activity, this type of current may help boost the amplitude of synaptic potentials in other neurons.
In September, 1999 my students and I began a new project related to some of my postdoctoral work with Dr. W. Otto Friesen at the University of Virginia. Otto and I, along with Pat Mangan (another postdoc in the lab) were studying neurons controlling leech swimming behavior and their modulation by serotonin, an important neurohormone and neurotransmitter found in a wide range of animals, including humans. Leeches with higher levels of serotonin in their blood are more likely to swim and to bite than leeches with lower levels. We examined the effects of serotonin on identified neurons involved in swimming behavior and found a variety of specific changes in the electrical properties of these cells. The focus of my current research is to identify and characterize the ionic currents in swim motor neuron DE-3 that are modified following exposure to serotonin.
Each fall semester, I teach neurobiology, a physiology course designed for Junior and Senior Biology majors. My course emphasizes the structure and function of neurons, including the ionic basis of neural signals and the cellular events underlying synaptic transmission. The laboratory is an essential element of the course in which concepts discussed in the classroom are reinforced with hands-on experience in a variety of experiments. I designed many of the experiments myself, again using the leech as a model system. In the lab, students in teams of three work with sophisticated equipment as they learn how to record neuronal electrical activity using intracellular microelectrodes, inject fluorescent dyes to reveal neuronal structure, and carry out a variety of more advanced experiments on synaptic transmission and circuit function. Where appropriate, students also perform interactive computer simulations of individual neurons and neuronal circuits. The culmination of the lab experience is an independent project of the students' own design.
Angstadt, J.D., A.M. Simone, and N.V. Peters (2011) Effects of riluzole on cell DE-3 of the medicinal leech: Evidence that a persistent sodium current contributes to postinhibitory rebound responses and bursting activity induced by calcium-channel blockers. Society Neurosci. Abst. 918.01.
Angstadt, J.D. (2012) Serotonin and flufenamic acid modulate postinhibitory rebound responses of an excitatory motor neuron in the medicinal leech. Society Neurosci. Abst. 648.24.
Vallecorsa GM, Amatrudo JM, and Angstadt JD (2007) Dopamine induces rhythmic activity and enhances postinhibitory rebound in a leech motor neuron involved in swimming and crawling behaviors. IMPULSE.
[IMPULSE is an on-line journal devoted to publishing undergraduate research. [impulse.appstate.edu/issues/2007.]
Angstadt JD, Grassmann JL, Theriault KM, and Levasseur SM (2005) Mechanisms of postinhibitory rebound and its modulation by serotonin in excitatory motor neurons of the medicinal leech. J Comp Physiol A 191:715-732. [pdf]
Angstadt JD (1999) Persistent inward currents in cultured Retzius cells of the medicinal leech. J Comp Physiol A 184:49-61. [pdf]
Angstadt JD, Choo JJ, and Saran AS (1998) Effects of transition metal ions on spontaneous electrical activity and chemical synaptic transmission of neurons in the medicinal leech. J Comp Physiol A 182:389-401.
(Former Siena students in bold )