The g.tec 8-/16-channel head-stages allow the recording of action potentials / spikes with g.USBamp. The boards are extremely small and lightweight and are connected via a very flexible cable to g.USBamp. This allows almost free motion of the animal. The electronic has an extremely low noise level and very high input impedance for high quality recordings. The channels have very similar gain and therefore a very high Common Mode Rejection Ratio is obtained. The head-stages can also be used for biosignal recordings like EEG or ECG in animals.

g.tec Headstages

Micro-wires and micro-electrode arrays (MEAs) have high impedances and must be very stable on the head of the animals. Therefore the electrodes are connected with a very flexible cable to the input of the headstage amplifier that has very high input impedance. It is important that this input impedance is magnitudes higher than the electrode impedance to pick up the neural activity correctly. Then operational amplifiers with precise gain are used to amplify the spikes and to drive the cable that connects the animal to the main recording system. The precise gain is especially important for a high common-mode rejection ratio (CMRR) (100 dB). The pre-amplifiers avoid also distortions in the signal such as power line interference, electromagnetic interference, cable artifacts.

g.HEADstage for 8 channels Connection with g.SPIKEsens

g.tec headstages are available with system connectors or with single channel connectors that can be interfaced to electrodes/wires easily. The head-stages are connected to the g.SPIKEsens power supply and filtering box that is connected to the g.USBamp. One g.SPIKEsens box supports up to 16 channels. Several headstages can be used simultaneously. The g.SPIKEsens box filters the signal between 0.5 Hz and 6000 Hz. Voltage Noise Density at 1 kHz is only 10 nV/SQRT(Hz).

The g.HEADstage is offered in two different types:

s The multi-pin headstage
s The golden-pin headstage

Highlights:
s Extremely small board (8 channels: 13 x 24 mm, 16 channels: 23.5 x 25 mm)
Low weight
Available for 8 –channels and 16 –channels
Easy connection to electrodes / wires; custom solutions available.
High quality neuronal activity recordings
1 LED slot to support easier video tracking with g.AnTS

Example: Recording of place cells in rats:

In-vivo recordings of action potentials in rats can be done by using the g.tec headstages, the biosignal amplifier g.USBamp and the real-time processing software g.USBamp Highspeed On-line Processing for Simulink. In the following example a rat was foraging for food in an arena of 80 cm x 80 cm size. The rat's path was investigated with a video camera based tracking system that transmitted the x- and y- positions to the recording computer. Simultaneously the neuronal activity was recorded with tetrodes (electrodes consisting of 4 wires) placed in the CA1 region of the hippocampus. This is a typical setup for place and grid cell recordings. This type of neurons increases its firing activity only when the animal is at a specific location of its environment. A typical firing rate map (firing frequency of the neuron vs. position) of a place cell is shown in the figure below. The averaged spike form  of this neuron is shown on the right side.


For more information please have a look at the g.tec Newsletter May 2009 Volume 24.
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