1, 3, 7, 16-Channel Single Electrode Systems / 4, 12, 28, 64-Channel Tetrode Systems

The multielectrode manipulator "System Eckhorn" was set up several years ago at the laboratory of Prof. Dr. R. Eckhorn at the Department of Neurophysics, Philipps-University Marburg, Germany and successfully used for parallel independent insertion of fiber microelectrodes through the intact dura into the brain of chronically prepared cats and monkeys.

The "Eckhorn" microdrive system is today available in a

1-, 3-, 7- or 16-electrode version

7- or 16-tetrode version with 28- or 64-recording channels

7- or 16-heptode version with 49- or 112-recording channels

With this fiber-electrode manipulator a broad range of even very thin shafted probes can be handled, including fiber and wire-electrodes with shaft diameters down to about 25 μm. The patented driving principle of the Eckhorn Manipulator offers an outstanding electrode positioning accuracy. Compared with hydraulic, direct motor driven or cable controlled microdrives, the patented fiber electrode manipulator "System Eckhorn" does not cause hysteresis errors of the electrode movement. Hysteresis error is generally a result of stiction and free motion of the driving mechanism. Our system has a higher degree of positioning accuracy due to its rubber tube driving mechanism being almost absoluy free of stiction and free motion.

Fig. 1: 7 Electrode (left) and 16 Electrode Eckhorn Matrix (right)

Using Thomas Eckhorn Matrix systems with patented rubber tube drive allows to record neural activity while the electrode is moving in the brain. So it is very easy to search active neurons in the brain. 

Fig. 2: Components of a 7 Electrode Eckhorn Matrix (without xyz-manipulator). In this case the Eckhorn Matrix is equipped with a rod to mount the drive to a stereotaxic instrument.

Fig. 3: 7 Electrode Eckhorn Matrix mounted to a XYZ-manipulator

The Thomas Eckhorn Matrix systems have some advantages in comparison to other multielectrode microdrive systems for neurophysiological research presently available on the market:

Vibration-free positioning of up to 16 quartz-platinum/tungsten microelectrodes in 1μm steps
Patented rubber tube driving principle
High positioning accuracy, due to lack of stiction and free motion
Easy exchange and calibration of microelectrodes within minutes
Advances up to 16 microelectrodes/tetrodes independently in 1μm steps up to 35.000μm (other electrode travel distances on request!)
Xyz-manipulator travel-distance: z=0-30mm, x= ±10mm, y=±10mm
Continuous low noise recording while the electrode scans the tissue at low velocity,

No noise introduction in the recordings so that you can search active neurons in the brain

No electrode connection cables free in air, no electrical noise pickup from environment (e.g. motors, radio stations)! Competitor drives pickup electrical interference from the environment so that you for example can hear radio station music or electrical artifacts from lab devices from the audio monitor loudspeaker instead of neural spikes!

Electrode moving velocity adjustable (1-250μm/s), moving direction selectable
Low noise 7 or 16 channel preamplifier is integrated into the microdrive chassis, system is compley shielded to avoid electrical noise pickup from the environment, three preamplifier operation modes: record, electrode impedance test, electrical stimulation/lesioning

System is compley delivered with motor control device, integrated preamplifier, software, xyz-manipulator, chamber holder, exchangeable head, handheld remote control, etc.

Exchangeable manipulator head allows manifold electrode configurations and interelectrode spacings

Electrode spacings from 80μm up to some millimeters possible due to exchangeable Eckhorn Matrix heads

The system is modular and adaptable to the end user′s requirements.

The Eckhorn Matrix is usable for cortical as well as deep brain recordings in all kinds of research applications

User friendly computer controlled system with LAN (local area network) communication via TCP/IP protocol between motor control unit and personal computer. Software package is part of the system. 

Using very thin shaft Thomas microelectrodes (outer diameter 80μm) causes minimal tissue damage.

Different neurophysiological methods are available for the Eckhorn Matrix systems (e.g. optogenetics, microinjection)

Fig. 4: Neural data recorded in a primate amygdala by using a 7 electrode Eckhorn Matrix (data kindly provided by Prof. Dr. Katalin Gothard, Arizona Health Science Center, Tucson, USA)

The Eckhorn Matrix system is available for small animal stereotaxic instruments (see figure 10) as well as for primate experiments (see figure 11).  

Fig. 5: Degrees of freedom of the 7 Electrode (left) and 16 Electrode Eckhorn Matrix XYZ manipulators

Exchangeable Heads
Thomas RECORDING offers a broad range of exchangeable Microdrive heads with different guide tube arrangements and electrode spacings for the 7- and 16-Electrode Eckhorn Systems. 

Fig. 6: 16 Electrode Eckhorn Matrix with Xyz-Manipulator and exchangeable microdrive head

Fig. 7: 16 Channel head with 4 individual adjustable groups of electrodes 4x(2x2)

Fig. 8: 16 Channel head with 4x4 offset electrode arrangement

There is a broad range of different Microdrive heads available. We also can offer customized solutions! 

Electrical Stimulation / Impedance Test with the Eckhorn Matrix

The Eckhorn Matrix preamplifier is integrated in the microdrive chassis and has three operation modes: Recording / Electrode Impedance Test /Stimulation or Lesioning. The standard operation mode of the preamplifier is “Recording”. To use the other two modes Thomas RECORDING offers a special designed device that is called Mode Selection & Impedance Test Device (MSD). 

The MSD is available for 7-/16-Electrode Eckhorn Matrix systems.

Each MSD consist of a main device housed in a 19” rack mountable cabinet and a small control box.

Fig. 9: Mode Selection & Impedance Test Device for 7- or 16-channel Eckhorn Systems (1)=MSD, (2)=Control Box

The control box is connected between the Eckhorn microdrive preamplifier and the MSD rack mountable device (#1 in figure 9). A stimulus generator, which is optional available, can be connected to the control box. With the MSD one can switch the stimulus generator output to the stimulation or lesioning electrode of the Microdrive system. The MSD allows to measure the electrode impedance while the electrode is already in the brain or in a saline solution. This offers you the opportunity to check whether the electrode is already ok for recording.  

Stereotaxic Equipment for the Eckhorn Matrix

Thomas RECORDING offers a broad range of solutions for mounting the Eckhorn multielectrode systems to stereotaxic instruments. Below you can find some examples for Eckhorn microdrives mounted to small (see fig. 10) and large animal stereotaxic instruments (see figure 11). It is our strength to adapt our Microdrive to stereotaxic setups. Please feel free to ask for your individual adaptation.

Fig. 10: 32 Electrode Eckhorn Matrix mounted to a Thomas RECORDING small animal stereotaxic instrument with a special halo holder.

Beside small animal stereotaxic instruments TREC offers also primate stereotaxic systems. 

Fig. 11: 16 Electrode Eckhorn Matrix mounted to a Thomas RECORDING primate stereotaxic instrument (PPS=Precision Positioning System) with a special halo holder.

Microinjection with the Eckhorn Matrix

For making drug injection experiments with the Thomas Eckhorn Matrix system we offer a special designed high pressure microinjection system. One of the 7- or 16-single microelectrodes of the Eckhorn Matrix can be replaced by a microinjection cannula. The microinjection cannula (OD=120μm) has a tapered tip and is equipped with the patented Thomas rubber tube drive so that you can position the microinjection cannula tip together with the recording microelectrodes with high positioning accuracy (better than 1μm). The microinjection system consists of a special designed and computer controlled syringe pump that is connected to the microinjection cannula via a special thick wall tubing. 

Figure 12: Microinjection pump (A), connection of thick wall tubing to syringe cannula (B)

The precision micro motor of the microinjection pump is controlled by the same motor control unit and graphical user interface as the Thomas Eckhorn Matrix. This guarantees a high precision and convenient experimental control of the injection/recording experiment. 

Optogenetic Equipment for the Eckhorn Matrix

Thomas RECORDING offers a complete range of Eckhorn Matrix accessories for optogenetic experiments. One of the 7- or 16 single microelectrodes or tetrodes is replaced by an optical fiber (OD=120μm). The optical fiber has a tapered tip and is equipped with the patented Thomas rubber tube drive so that you can position the optical fiber tip together with the recording microelectrodes with high positioning accuracy (better than 1μm). Figure 13 shows an Eckhorn Matrix head with concentric guide tube arrangement and a single optical fiber in the center position. The recording microelectrodes are concentrically arranged around the optical fiber in the center of this arrangement.  

Figure 13: 7 Electrode Eckhorn Matrix concentric head with one optical fiber and 6 recording electrodes.