PROGRAMMABLE ELECTRODE SWITCHING FOR CORTICAL STIMULATION & ECOG
The g.Estim PRO Switching Unit is a programmable 256-channel electrode switching matrix for cortical stimulation and electrophysiological recording. It dynamically routes selected implanted electrodes between stimulation and recording pathways, enabling researchers and clinicians to stimulate and record cortical activity using the same electrode setup.
Combined with g.Estim PRO and g.HIamp, the Switching Unit enables synchronized stimulation and ECoG recording for functional brain mapping, CCEP measurements and advanced stimulation research. Electrode switching is completed within 6 ms, while digital synchronization allows the switching state to be recorded together with electrophysiological data.
For research applications, integration with g.HIsys and MATLAB/Simulink enables programmable electrode selection and automated stimulation-and-recording workflows.
| Up to 256 electrode channels | Programmable routing of implanted electrodes between stimulation and recording pathways |
| 6 ms electrode switching | Switching completed within 6 ms after a digital input edge |
| Stimulate & record | Combine g.Estim PRO and g.HIamp for cortical stimulation and ECoG recording |
| Precise synchronization | Digital I/O synchronizes switching with stimulation and electrophysiological acquisition |
| Advanced impedance analysis | Measure electrode impedance from 20–1000 Hz across 1–800 kΩ |
| Programmable research workflows | Control electrode selection and switching with g.HIsys and MATLAB/Simulink |
| High stimulation capability | Supports stimulation up to 80 V, 15 mA and 500 Hz |
| Designed for intracranial electrophysiology | Low-noise, low-crosstalk signal routing for cortical recording applications |
| Electrode channels | Up to 256 |
| Electrode organization | 4 groups of 64 channels |
| Switching time | 6 ms from DI rising edge to completed switching |
| Switching release time | 6 ms from DI falling edge to completed switching |
| Minimum Active State | 1 ms |
| Maximum stimulation voltage | 80 V |
| Maximum stimulation current | 15 mA |
| Maximum stimulation frequency | 500 Hz |
| Channel input range | ±340 mV |
| Channel coupling | AC, 0.16–70 kHz |
| Channel crosstalk | ≤−70 dB |
| Input-referred noise | ≤6 µV peak-to-peak, 0.5–50 Hz at 256 Hz sampling |
| Typical input-referred noise | <1 µV RMS, 1–30 Hz |
| Calibrated channel offset | <±50 µV |
| Digital input trigger duration | >200 µs |
| Digital input HIGH | 2.0–3.3 V DC |
| Digital input LOW | 0.0–0.8 V DC |
| Digital output HIGH | 2.4–3.3 V DC |
| Digital output LOW | 0.0–0.4 V DC |
SWITCH BETWEEN CORTICAL STIMULATION & ECoG RECORDING
The g.Estim PRO Switching Unit enables selected electrodes within the same implanted electrode array to be routed between stimulation and recording pathways. Combined with g.Estim PRO and g.HIamp, the system allows cortical activity to be recorded between and during stimulation without changing the electrode setup.
With programmable routing of up to 256 electrode channels, researchers can select stimulation sites while maintaining high-channel-count ECoG acquisition, supporting functional brain mapping, CCEP measurements and advanced cortical stimulation research.
SYSTEMATICALLY STIMULATE, RECORD & MAP CORTICAL NETWORKS
The g.Estim PRO Switching Unit enables programmable electrode routing for CCEP and functional connectivity research. Selected electrode pairs can be sequentially routed for stimulation while cortical responses are recorded with g.HIamp, allowing researchers to investigate functional connections across implanted electrode arrays.
Combined with g.Estim PRO, g.HIamp and g.HIsys, stimulation, electrode switching and ECoG acquisition can be synchronized and automated for systematic cortical network mapping. This enables efficient investigation of stimulation-response relationships across multiple cortical sites.
AUTOMATE ELECTRODE ROUTING FOR CUSTOM RESEARCH WORKFLOWS
For advanced research applications, the g.Estim PRO Switching Unit can be controlled directly from MATLAB/Simulink with g.HIsys. Researchers can programmatically select electrodes for Stim+, Stim− and GND, control switching states and integrate hardware triggering into custom stimulation and recording workflows.
This enables automated electrode sequences and real-time experimental logic, making it possible to build sophisticated workflows for CCEP mapping, functional connectivity research and closed-loop cortical stimulation.
ADVANCED ELECTRODE IMPEDANCE ANALYSIS
The g.Estim PRO Switching Unit supports advanced impedance measurements across a frequency range of 20–1000 Hz and an impedance range of 1–800 kΩ. This allows researchers to characterize electrode impedance under different measurement conditions before stimulation and recording.
The Impedance Measurement Tool provides configurable measurement settings, visualization of impedance results and report generation for documentation and further analysis.
sEEG STIMULATION & RECORDING IN HUMAN OCD RESEARCH
Nho, Young-Hoon, et al. – Cell 189.3, 2026
Researchers investigating treatment-resistant obsessive-compulsive disorder (OCD) recorded intracranial neural activity from up to 240 sEEG electrode contacts using a 256-channel g.HIamp.
The experimental setup connected the g.Estim PRO stimulation system through the g.Estim PRO Switching Unit, enabling stimulation and neural recording without manual switching between the two pathways. This allowed high-channel-count sEEG recording and targeted electrical stimulation to be integrated within the same experimental setup.
SWITCHING BETWEEN REAL-TIME ECoG & DIRECT CORTICAL STIMULATION
Noll et al. – Neuro-Oncology Practice, 2024
Researchers at MD Anderson Cancer Center demonstrated an intraoperative language-mapping workflow combining real-time ECoG with direct cortical stimulation during awake brain surgery. The setup used g.Estim PRO, the g.Estim PRO Switching Unit, g.HIamp and g.HIsys.
The Switching Unit enabled electrode contacts to be switched between recording and direct cortical stimulation. Real-time gamma-band ECoG identified a language-related cortical region that corresponded with direct cortical stimulation results, where stimulation at 6 mA produced consistent speech arrest during object and action naming tasks.
MAPPING PATHOLOGICAL BRAIN NETWORKS WITH CCEP
Kamada et al. – Frontiers in Neurology, 2020
Kamada et al. investigated functional and pathological brain networks in 14 patients with intractable epilepsy using electrical stimulation, CCEPs and high-gamma mapping. Intracranial activity was recorded with a 256-channel g.HIamp, while stimulation at different cortical sites was used to investigate functional connectivity.
The work demonstrates how electrical stimulation and high-channel-count intracranial recording can be combined to identify functional and pathological cortical networks. g.tec’s subsequent CCEP workflow specifically uses the g.Estim PRO Switching Unit for software-controlled selection of stimulation sites and automated CCEP screening.
TIMING CORTICAL STIMULATION TO HIGH-GAMMA BRAIN ACTIVITY
Kamada et al. – Epilepsy & Behavior Reports, 2026
Researchers investigated whether the timing of electrical cortical stimulation (ECS) relative to high-gamma activity (HGA) could influence language function during picture naming. The setup combined g.Estim PRO and the g.Estim PRO Switching Unit for selecting stimulation electrode pairs, 256-channel g.HIamp for ECoG recording and g.HIsys for synchronized task presentation and experimental control.
Short cortical stimulation delivered before individual HGA peaks produced substantially more language errors and longer response times than stimulation after the peaks. The results demonstrate how precisely timed cortical stimulation and high-channel-count ECoG can be combined to investigate the dynamics of functional brain networks and potentially improve functional brain mapping strategies.
FREQUENTLY ASKED QUESTIONS
Yes. The g.Estim PRO Switching Unit routes selected electrodes between the stimulation and recording pathways. Combined with g.Estim PRO and g.HIamp, this enables stimulation and electrophysiological recording using the same implanted electrode setup without manually reconnecting electrodes.
The Switching Unit supports up to 256 electrode channels, organized in four groups of 64 channels. Selected electrodes can be programmatically assigned to stimulation and recording pathways.
Electrode switching is completed within 6 ms after a digital input edge. The release from the active switching state is also completed within 6 ms. The minimum Active State is 1 ms.
The Switching Unit provides digital input and output interfaces for hardware synchronization. A digital trigger can initiate the switching process, while the Switching Unit’s digital output can be connected to g.HIamp so that the switching state is recorded together with the electrophysiological data.
Yes. In research configurations, electrode selection, switching, stimulation and ECoG acquisition can be integrated into automated workflows. This allows stimulation sites to be systematically changed while evoked cortical responses are recorded across the implanted electrode array, supporting CCEP and functional connectivity mapping.
Yes. With g.HIsys, researchers can integrate the Switching Unit into MATLAB/Simulink workflows. Electrode assignments for Stim+, Stim− and GND, switching states, hardware triggers and automated stimulation sequences can be controlled programmatically.
When the Switching Unit is combined with g.HIamp, cortical signals can be recorded between and during stimulation. The selected stimulation electrodes are routed to the stimulation pathway while the system supports electrophysiological acquisition from the remaining recording channels.
The g.Estim PRO Switching Unit is specified for stimulation voltages up to 80 V, currents up to 15 mA and stimulation frequencies up to 500 Hz. The actual stimulation parameters and permitted use depend on the connected stimulator and the respective application and operating mode.
The signal path is designed for intracranial electrophysiology with a channel input range of ±340 mV, AC coupling from 0.16–70 kHz, channel crosstalk of ≤−70 dB, calibrated channel offset below ±50 µV, and typical input-referred noise below 1 µV RMS from 1–30 Hz.
Yes. The Switching Unit supports advanced electrode impedance measurements from 20–1000 Hz across an impedance range of 1–800 kΩ. This allows researchers to characterize electrode impedance across different frequencies as part of the preparation and documentation of stimulation and recording experiments.
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