Achim Klug , Ph.D. Assistant Professor Department of Physiology & Biophysics
	UCD Anschutz Medical Campus RC-1 North Tower 7120 PO Box 6511, Mail Stop F8307 Tel (303) 724-4621 Fax (303) 724-4501	E-mail: achim.klug@ucdenver.edu CV

CURRENT RESEARCH

One fascinating aspect of the auditory system is that a significant part of information processing is performed by subcortical brain areas, i.e. nuclei located in the brain stem or midbrain. Each one of these nuclei modifies the incoming stream of information in particular ways, which depend on the properties of the inputs the nucleus receives, as well as the cellular and synaptic properties of the involved neurons. The output of one auditory center subsequently serves as input to the next higher center, such that the incoming stream of information is modified and analyzed in a multi-step process and from nucleus to nucleus.

We would like to understand how exactly the incoming stream of auditory information is modified by the various auditory centers. To be able to do this, one needs to understand 1) the inputs the nucleus receives and the specific properties of these inputs 2) how the synapses across which information travels changes the stream of information and 3) how the specific ion channels and membrane properties of the neuron modify information.

In order to address all three aspects, a variety of methods is required. So we use in vitro electrophysiological techniques (such as patch clamp) to study the cellular components of the pathway. A combinatorial approach of in vivo and in vitro techniques allows us to understand how auditory neurons are connected to each other, how the different inputs to a given neuron interact with each other, and how synapses modify incoming steams of activity. Computer modeling allows us to understand how the various components of a neural circuit work together in information processing. Anatomical methods such as tracer studies and antibody labeling aids in the understanding of the connection pattern between nuclei.  

Image 1

Image 1 shows labeled synapses in the medial nucleus of the trapezoid body (MNTB) of the auditory brainstem. These giant synapses termed ‘calyces of Held’ produce very large and fast synaptic currents and inject these currents directly into the soma of the postsynaptic neuron. Calyces of Held as well as their postsynaptic MNTB principal neurons show a number of specializations for information processing with very high temporal fidelity. This fidelity is required, as the MNTB functions as an important source of well-timed inhibition for many centers of the auditory brainstem, and plays an important role in sound localization. The image shows calyces (presynaptic terminals) as well as afferent auditory fibers filled with fluorescent tracer (green).

Image 2

Image 2 shows a magnified view of several labeled calyces (red) that synapse directly onto MNTB principal cell bodies (green)

Image 3

Image 3 shows an overview of a different auditory brainstem nucleus, the medial superior olive (MSO). Neurons in this nucleus measure the relative arrival time of sound between the two ears and thus compute the location of a sound source in space. The image shows a number of MSO principal neurons (cell bodies indicated in blue) which have two sets of dendrites emerging from either end (green). The dendrites receive excitatory inputs from both ears, while the cell bodies also receive inhibitory inputs from both ears (shown in red).

Image 4

Image 4 shows a magnified view of the cell body of an MSO principal neuron (green) with a number glycine receptors (red).

Current lab colleagues
     

Selected Publications