One of the least understood aspects of autonomic neurobiology concerns the central mechanisms responsible for the control of sympathetic nerve discharges. There is considerable data supporting the view that disturbances in control of autonomic nerve activity can contribute to the development or maintenance of hypertension, cardiac dysrhythmias, and other cardiovascular diseases. Recent work demonstrates that different rhythms are evident in sympathetic nerve activity depending upon the experimental conditions. The major objectives of the research in our laboratories are 1) to determine which regions of the brain contain the neurons responsible for the different rhythms in sympathetic activity, 2) to identify the interconnections of single neurons with activity
correlated to sympathetic nerve activity, 3) to determine what role the different rhythms play in regulating vasomotor tone and in mediating complex and highly differentiated cardiovascular response patterns as occur during defense,exercise, and sleep.

Selected Achievements since 2001

Invited Speaker, Satellite Symposium of 34th Congress of International Union of Physiological Sciences on “Central mechanisms of Cardiovascular Control – Integrative, Cellular and Molecular Aspects,” Sydney, Australia, August, 2001.

Invited Speaker, Federation of the European Physiology Societies Workshop on European Study Group on Cardiovascular Oscillations,” Siena, Italy, April, 2002.

Invited Speaker, Federation of the European Societies Workshop on “Cardiovascular Oscillations III.” Leuven, Belgium, May 10-12, 2004.

Selected Samples of Publications Since 2001

Lewis CD, Gebber GL, Larsen PD, Barman SM: Long-term correlations in the spike trains of medullary sympathetic neurons. J. Neurophysiol. 85(4): 1614-1622, 2001.

Larsen PD, Zhong S, Gebber GL, Barman SM: Sympathetic nerve and cardiovascular responses to chemical activation of the midbrain defense region. Amer. J. Physiol. 280(6): R1704-R1712, 2001.

Orer HS, Barman SM, Gebber GL: Effects on sympathetic activity of 8-OHDPAT and clonidine in cat medullary lateral tegmental field. Amer. J. Physiol. 281(2): H613-H622, 2001.

Barman SM, Gebber GL, Orer HS: The role of the medullary lateral tegmental field in the generation and baroreceptor reflex control of sympathetic nerve discharge in the cat. In “Neurocardiovascular Regulation: From Molecules to Man” (M.W. Chapleau and F.M. Abboud, eds.). Annl. N.Y. Acad. Sci. 940: 270-285, 2001.

Barman SM, Orer HS, Gebber GL: Differential effects of an NMDA and a non-NMDA receptor antagonist on medullary lateral tegmental field neurons. Amer. J. Physiol. 282(1): R100-R113, 2002.

McAllen R, Allen A, Malpas S; Barman SM, Gebber GL, Orer HS: Sympathetic vasomotor tone—time to move beyond the network oscillator hypothesis. Amer. J. Physiol. 283(5): R1285-1286; author reply R1286-R1287, 2002.

Zhou SY, Gebber GL, Zhong S, Barman SM: Pathways involved in synchronization of sympathetic nerve discharge to lung inflation. Brain Res. 931(2): 107-116, 2002.

Das M, Gebber GL, Barman SM, Lewis CD: Fractal properties of sympathetic nerve discharge. J. Neurophysiol. 89(2): 833-840, 2003.

Orer HS, Das M, Barman SM, Gebber GL: Fractal activity generated independently by medullary sympathetic premotor and preganglionic sympathetic neurons. J. Neurophysiol. 90(1): 47-54, 2003.

Gebber GL, Barman SM: From the top down: An alternative to reductionist views on the central neural control of cardiovascular function. Recent Res. Develop. Physiol. 1: 367-384, 2004.

Orer HS, Gebber GL, Phillips SW, Barman SM: Role of the medullary lateral tegmental field in reflex-mediated sympathoexcitation in cats. Amer. J. Physiol. 286(3): R452-R464, 2004.

Fadel PJ, Orer HS, Barman SM, Vongpatanasin W., Victor RG, Gebber GL: Fractal properties of human muscle sympathetic nerve activity. Amer. J Physiol. 286(3); H1076-H1087, 2004.

Gebber GL, Das M, Barman SM: An unusual form of phase walk in a system of coupled oscillators. J. Biol. Rhythms 19(6): 542-550, 2004.

Fadel PJ, Barman SM, Phillips SW, Gebber GL: Fractal fluctuations in human respiration. J. Appl. Physiol. 97(6): 2056-2064, 2004.

Gebber GL, Barman SM: What’s all the noise about? Distinguishing fractal from random processes in the sympathetic nervous system. Recent Res. Develop. Physiol. 2: 167-186, 2004.

Barman SM, Orer HS, Gebber GL: The role of the medullary lateral tegmental field in the control of sympathetic nerve discharge. Recent Res. Develop. Physiol. 2: 187-207, 2004.