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Julie Haas, Ph.D.

 

Julie S. Haas, Ph.D.
Assistant Professor
Neuroscience

Department of Biological Sciences
Iacocca Hall, Room D226
111 Research Drive
Bethlehem, PA 18015
610-758-6276 (voice)
610-758-4004 (fax)

julie.haas@lehigh.edu

 

 

Dr. Haas's research is funded by the Brain & Behavior Foundation and the Whitehall Foundation.

  • Research
  • Publications
  • People
  • Positions Available

Research

Julie Haas, Ph.D.

Our research is focused on electrical synapses.  Formed by pores that connect the cytoplasm of coupled cells, these synapses allow ions and information to flow directly between neurons.

We are interested in determining the relationships between electrical synaptic strength, synchrony in circuits of coupled neurons, and the more abstract process of attention.  These ideas coalesce within the thalamus, in a specific nucleus where electrical synapses are particularly dense; it is this nucleus that is thought to gate cortical attention to the sensory surround.  I hypothesize that the strength of electrical synapses within this nucleus is a crucial component for the control of human attention.

To study electrical synapses, our main tool is dual whole-cell patch clamping.  In the image above, two electrode tips are shown in preparation for patching the two cell bodies, which are connected by an electrical synapse (also known as a gap junction) where the ‘arms’ of the two neurons cross.

Electrical synapses can share and cause spiking activity between coupled neurons.  In the example above, the spikes in one cell (grey) of a coupled pair caused spikes in its coupled neighbor (black).  With these methods, we measure strength of electrical synapses before and after the cells are active together.

We also stimulate activity in electrically coupled neurons with optogenetics, the newest coolest tool in neuroscience.  Light-sensitive channelrhodopsin channels are delivered to neuronal membranes through either viral injection or breeding transgenetic animals. Shown above is a slice of mouse tissue under brightfield illumination (left) and fluorescent reporting of ChR2 expression (right).  In vitro, we provide 490 nm light to neurons, and they respond by spiking.

The Haas Lab - 2014
Julie Haas, Ph.D.

(l-r) Jessica Sevetson (Lab Technician); Undergraduate Researchers: Sarah Fittro, Emily Heckman, Bijal Desai; Julie Haas, Ph.D., Principal Investigator

 

 

Publications

Vogels TP, Froemke R, Doyon N, Gilson M, Haas JS, Liu R, Maffei A, Miller P, Wierenga P, Woodin M, Zenke F and Sprekeler H (2013). Inhibitory synaptic plasticity: Spike-timing dependence and putative network function. Frontiers in Neural Circuits 7:119.

Haas JS and Landisman CE (2012) Bursts modify electrical synaptic strength. Brain Research, special issue on Electrical Synapses, in press.

Haas JS, Zavala B and Landisman CE (2011) Activity-dependent long-term depression of electrical synapses.
Science 334(6054):389-393.

Haas JS and Landisman CE (2011) State-dependent modulation of gap junction signaling by the persistent sodium current. Frontiers in Cellular Neuroscience 5:31.

Haas JS, Kreuz T, Torcini A, Politi A, Abarbanel HDI (2010) Rate maintenance in spiking neurons driving with strong inputs of varying speeds. European Journal of Neuroscience 32(11):1930-9.

Kreuz T, Chicharro D, Andrzejak RG, Haas JS,  Abarbanel HDI, Politi A (2009). Measuring multiple spike train synchrony. J. Neurosci. Methods 182(2):287-299.

Kreuz T, Haas JS, Morelli A, Abarbanel HDI, Politi A (2007). Measuring spike train synchrony. J. Neurosci. Methods 165(1):151-61.

Haas JS, Dorval AD, White JA (2007). Contributions of Ih to feature selectivity in layer II stellate cells of the entorhinal cortex. J. Computational Neuroscience 22(2):161-71.

Haas JS, Nowotny TN, Abarbanel HDI (2006). Spike-timing-dependent plasticity at inhibitory synapses in the entorhinal cortex. J. Neurophysiol 96: 3305-3313.

Netoff TI, Banks MI, Dorval AD, Acker CD, Haas JS, Kopell N, White JA (2004). Synchronization in hybrid neuronal networks of the hippocampal formation. J. Neurophysiol. 93(3):1197-1208.

Haas JS and White JA (2002). Frequency selectivity of layer II stellate cells in the medial entorhinal cortex.
J. Neurophysiol. 88(5): 2422-2429.

Book Chapters:

Abarbanel HDI, Haas JS, Talathi SS (2007) Synapses and neurons: Basic properties and their use in the recognition of environmental signals. In Lecture Notes in Supercomputational Neuroscience, Springer-Verlag.

White JA and Haas JS (2001) Noise from voltage-gated ion channels: effects on dynamics and reliability in intrinsically oscillatory neurons. In Handbook of Biological Physics, Vol. 4,  F Moss and S Gielen (eds.), Elsevier Press, Amsterdam.

Lab Personnel

Julie Haas, Ph.D. Jessica Sevetson
Julie Haas, Ph.D.
Principal Investigator
Jessica Sevetson
Lab Technician

 

Undergraduate Researchers
Bijal Desai Emily Heckman Sarah Fittro
Bijal Desai Emily Heckman Sarah Fittro

Positions Available

Post-Doc Position:

We seek a postdoctoral researcher who is highly motivated to study the plasticity of electrical synapses in mammalian brain slices using electrophysiological and optogenetic approaches, under the direction of Dr. Julie Haas. Our work relies on a combination of techniques, including dual-cell recordings in vitro, quantitative analyses, computational modeling and histology. Prior experience with in vitro electrophysiology, optogenetic methods and proficiency in MATLAB is highly desirable. Located proximally to NYC and Philadelphia, the Lehigh community provides an ambitious, supportive and collaborative research environment, and offers excellent training and career development opportunities.

Interested candidates should send their CV, a brief cover letter indicating your research interests and goals, and the names and contact information for three professional references to Dr. Julie Haas

Appointment is a renewable one-year contract at the appropriate NIH salary scale.

 

 

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