My research focuses on the development of the visual system. We use the relatively simple and experimentally tractable visual system of Xenopus laevis tadpoles. By understanding the role that sensory experience plays in the development of this system we will begin to understand the guiding principles by which the brain wires itself up during development.

Biography

My interest in neuroscience began as an undergraduate here at Brown, where I worked in visual cortical synaptic plasticity in the laboratory of Mark Bear. As a PhD student in Johns Hopkins with David Linden, I studied plasticity of inhibitory inputs and of intrinsic excitability of deep-cerebellar nuclear neurons. My postdoctoral work was done in the lab of Holly Cline, where I combined my interest in the visual system with my interest in the regulation of neural excitability, work which continues in my current lab. I have been at Brown since summer 2004.

Institutions

BU

Research Description

The long-term goal of my research is to understand the role of experience in the development of neural circuits. To address this question it is necessary to first understand what mechanisms regulate and maintain the normal morphology, synaptic connectivity, excitability, and output properties of the neurons that constitute these circuits, and then observe how these mechanisms are affected by experience. Over the last few decades, research has shown that neural activity plays a critical role during the development of the visual system. However, less is known about how the visual system adapts to neural activity over a shorter time scale during development. This is important, since neurons must be able to function within a useful dynamic range when faced with changing environmental and developmental conditions. In order to do this, neurons have been shown to homeostatically adapt their synaptic and intrinsic electrophysiologically relevant conditions. By understanding how the developing nervous system responds and adjusts to periods of enhanced activity we can begin to comprehend how this activity can be maximally utilized to guide long-term developmental changes.

In my research I address these issues by taking advantage of the Xenopus laevis tadpole visual system. The optictectal neurons in the tadpole receive direct monosynaptic inputs from the contralateral retina, and form a developmental gradient where it is possible to study neurons at different stages of their development in the same preparation. The synaptic and dendritic maturation of tectal neurons is well characterized and provides a starting point from which to study the roles that visual experience and a variety of signaling mechanisms play in these processes. Moreover, tectal neurons are easily accessible, allowing us to take advantage of several established techniques for altering gene expression in individual neurons and then observe the effects of these genes of interest in the electrophysiological and morphological properties of these cells.

My research has used a novel approach where freely swimming tadpoles are presented with a moving visual stimulus for a few hours. This allowed us to directly test the effects of visual experience over a relatively short timescale in a highly plastic, developing nervous system. A variety of mechanisms have emerged where tectal neurons respond to persistent visual stimulation by altering both their intrinsic excitability and their synaptic properties. We are now in a position to study these mechanisms in depth using diverse electrophysiological, imaging and molecular techniques.

Awards

1993 Sigma Xi, scientific honors society
1995-2000 Howard Hughes Predoctoral Fellowship
1999 David Israel Macht Young Investigator Prize
2001-2002 Epilepsy Foundation research training fellowship
2004-2007 Klingenstein Foundation Fellow
2004-2008 American Heart Association Starter Scholar Award

Affiliations

Society for Neuroscience
American Physiological Society

Funded Research

a. Current Grants

NIH – 1R01EY019578-01A1 1/01/2010 – 12/31/2012
Cellular basis of visually-guided behavior during development
Role: PI

NSF – IOS-0746558 4/01/08 – 3/31/13
CAREER Award
CAREER: Cellular determinants of visual system function and development,
Role: PI

b. Completed Grants

Whitehall Foundation 7/01/08 – 6/31/11
Research Grant
A developmental role for the regulation of neuronal excitability in the Xenopus visual system.
Role: PI

NSF – 2007059474 9/01/07 – 8/31/10
GRFP for Mark Bell
Role: Mentor

Brown University – Dean of the College 9/2008 – 9/2009
Curricular Development Grant
Role: PI

American Heart Association – National Chapter 9/01/04 - 7/01/08
Starter Scholar Award
Physiological regulation of polyamine synthesis by neural activity: a novel neuroprotective mechanism?
Role: PI

NIH - 5F32EY016939-02 7/01/06 – 6/30/08
NRSA for Kara Pratt
Role: Mentor

Klingenstein Foundation 7/01/04 – 7/01/08
Klingenstein Fellow
Visual activity-driven regulation of intrinsic excitability in the developing visual system
Role: PI



Brown University BSP 3/01/06 – 4/01/07
Pilot Project Grant
Development of microscale optical probes to study development of the visual system in vivo.
Role: Co-PI


Rhode Island Foundation 1/01/07 – 12/31/07
Medical Research Grant
Experience-dependent development of a neural circuit.
Role: PI

Teaching Experience

NEUR 1020 Principles of Neurobiology
NEUR 1930 Great Controversies in Neurobiology

Courses Taught

• Great Controversies in Neurobiology (BN0193.4)
• Principles of Neurobiology (BN0102)

Selected Publications

• MR. Bell and C.D. Aizenman. A novel neuroprotective role for polyamines in a Xenopus tadpole model of epilepsy. Nature Neuroscience 14(4):505-12 (2011). PMID: 21378970(2011)
• K. Deeg and CD Aizenman. Modality-specific homeostatic plasticity in the developing tectum. Nature Neuroscience 14(5):548-50 (2011). PMID: 21441922(2011)
• H Xu, AV Nurmikko, CD Aizenman. ""Visual experience-dependent maturation of correlated neuronal activity patterns in a developing visual system." Journal of Neuroscience, 31(22):8025-36 (2011). PMID: 21632(2011)
• ES Ruthazer, CD Aizenman. "Learning to See: Patterned activity and the development of visual function". TINS Feb. (2010). PMID: 20153060(2010)
• RH Lee, EA Mills, MR Bell, KE Deeg, N Marsh-Armstrong, CD Aizenman. "Neurodevelopmental effects of chronic exposure to elevated levels of pro-inflammatory cytokines in a developing visual system". Neural Development. 5:2 (2010) PMID: 20067608(2010)
• BA Richards, CD Aizenman, CJ Akerman. In vivo spike-timing dependent plasticity in the optic tectum of Xenopus laevis. Frontiers in Synaptic Neuroscience (in press - 2010). PMID: 21423493(2010)
• W. Dong, RH Lee, H Xu, S Yang, KG Pratt, V Cao, YK Song, A Nurmikko, C.D. Aizenman. Visual avoidance is correlated with the maturation of visual responses in the optic tectum. Journal of Neurophysiology 101(2):803-15. (2009). PMID: 19073807(2009)
• KG Pratt and CD Aizenman. Multisensory integration in mesencephalic trigeminal neurons in Xenopus laevis. Journal of Neurophysiology 102(1):399-412. (2009). PMID: 19386750(2009)
• K Deeg, IB Sears and CD Aizenman. Development of multisensory convergence in the Xenopus optic tectum. Journal of Neurophysiology 102(6):3392-404 (2009). PMID: 19793878(2009)
• R.C. Ewald, K.R. Van-Keuren-Jensen, C.D. Aizenman and H.T. Cline. "Roles of NR2A and NR2B in the development of dendritic arbor morphology in vivo." Journal of Neuroscience, 28(4):850-61 (2008). PMID: 18216193(2008)
• H. Xu*, K.M. Davitt*, W. Dong, Y-K. Song, W.R. Patterson III, C.D. Aizenman, A.V. Nurmikko. "Combining multicore imaging fiber with matrix addressable blue/green LED arrays for spatiotemporal photonic excitation at the cellular level." IEEE JSTQE 14(1):167-70 (2008). PMID – N/A(2008)
• K.G. Pratt, W. Dong and C.D. Aizenman. "Development and spike-timing dependent plasticity of recurrent excitation in the Xenopus optic tectum." Nature Neuroscience 11(4):467-75 (2008). PMID: 18344990(2008)
• C.D. Aizenman and K.G. Pratt. "There's more than one way to scale a synapse." Neuron 58(5):651-3. (2008). PMID: 18549775(2008)
• K. G. Pratt and C. D. Aizenman. "Homeostatic regulation of intrinsic excitability and synaptic transmission in a developing visual circuit," Journal of Neuroscience, 27(31):8268-77 (2007). PMID: 17670973(2007)
• C.D. Aizenman and H.T. Cline. "Enhanced Visual Activity in vivo Forms Nascent Synapses in the Developing Retinotectal Projection." Journal of Neurophysiology, 97(4):2949-57 (2007). PMID: 17267761(2007)
• C. D. Aizenman, C. J. Akerman, K.R. Jensen and H.T. Cline. "Visually driven regulation of intrinsic neuronal excitability improves stimulus detection in vivo." Neuron, 39: 831-842 (2003). PMID: 12948449(2003)
• C.D. Aizenman, G. Muñoz-Elias and H.T. Cline. "Visually driven modulation of glutamatergic synaptic transmission is mediated by the regulation of intracellular polyamines." Neuron, 34(4):623-634 (2002). PMID: 12062045(2002)
• C.D. Aizenman and D.J. Linden. "Rapid, Synaptically-Driven Increases in the Intrinsic Excitability of Cerebellar Deep Nuclear Neurons." Nature Neuroscience , 3:109-111 (2000). PMID: 10649564(2000)