CORTICAL ELECTRODES FOR BRAIN MAPPINGS

cortiQ cortical electrodes allow high-quality ECoG recordings in the intensive care unit or operating room. The implantation of these ECoG electrodes is done during a surgical procedure to perform brain-mapping, brain-stimulation or neuroscience experiments. Typically, the time frame available for the ECoG recordings is very limited. For that reason, the ECoG electrodes have to perform all the time, and you need to be able to connect them to the recording equipment quickly.

Thanks to the unique laser manufacturing process, cortiQ cortical electrodes are very soft, thin, and flexible. This is especially important because they have to adapt well to the brain’s curvature. The cortiQ ECoG electrodes are made of Platinum-Iridium for highest signal quality recordings!

cortiQ ECoG electrodes are seamlessly integrated into g.tec’s biosignal amplifiers and software solutions. Thus, they are perfectly suited for performing brain mapping with cortiQ, CCEP-, neuromodulation- and BCI-experiments. They are connected with a connector cable to 1.5 mm safety connectors to interface with the g.HIamp 64 channels Passive Electrode Connector Box. Furthermore, they can be interfaced directly to the multi-pole g.HIamp connector with a cortiQ quick connector, which provides a quick connection.

cortiQ cortical electrodes also provide increased patient safety due to the interlocking structure of its material, and prevents separation of electrode contacts.

PRODUCT HIGHLIGHTS

High-quality ECoG recordings
Fully integrated into the g.tec Suite 2020 and cortiQ
Makes BCI experiments, CCEPs and high-gamma mapping easy
The electrodes have an R indicator to indicate the top and bottom sides
The products are made for single use
Connectors for the connection cable are included
The product is supplied sterile
The electrodes have a color code to allow to identify the grid or strip that is implanted
The cortiQ cortical electrode can be used with g.Estim PRO for cortical stimulation

TECHNICAL SPECIFICATIONS

The distance from electrode to electrode10 mm
Contact diameter4 mm (contact opening is 2.7 mm)
Electrode cable length370 mm
MaterialPlatinum-Iridium
Strips1x4, 1x8
Grids2x8, 4x5 and 8x8
CertificationFDA cleared

I use ECoG electrodes for real-time brain mappings to find and interpret functional activity in the brain at the bed-side, and during awake craniotomy for brain surgery. Brain mapping with ECoG applies as novel mapping technique, revealing hidden brain functions that are active when the patient performs semantic, motor, visual, auditory, tactile, attentional, and/or other tasks. Therefore, I can reduce electrical cortical stimulations (ECS) to minimize related seizures and shorten clinical examinations. Otherwise, I would miss an opportunity to improve existing brain mapping procedures and learn the bigger picture.

Kyousuke Kamada, PhD, MD - Hokashin Group Megumin Hospital, Sapporo, Japan

“Fused with a variety of rapid prototyping and research software tools, g.HIamp serves as a unique tool in our clinical research applications to record electrocorticogram and local field potentials. The oversampling process executed by the internal DSP provides exceptional SNR and enables capturing higher frequency brain rhythms with superior quality.”

Nuri Firat Ince, PhD - University of Houston, USA

HIGH-GAMMA ACTIVITY

While most BCIs rely on the EEG, some of the latest work has drawn attention to BCIs based on ECoG. ECoG based systems have numerous advantages over EEG systems, including

  • higher spatial resolution
  • higher frequency range
  • fewer artifacts
  • no need to apply gel or mount a cap before use

Recent research has demonstrated, over and over, that ECoG can outperform comparable EEG methods because of these advantages. Scientific work showed that ECoG methods can not only improve BCIs but also help us address fundamental questions in neuroscience. A few efforts have sought to map “eloquent cortex” with ECoG. That is, scientists have studied language areas of the brain while people say different words or phonemes. Results revealed far more information than EEG based methods and have inspired new ECoG BCIs that are impossible with EEG BCIs. Other work explored the brain activity associated with movement.

This has been very well studied with the EEG, leading to the well-known dominant paradigm that real and imagined movement affects activity in the 8-12 Hz range. ECoG research showed that this is only part of the picture. Movement also affects a higher frequency band, around 70-200 Hz, which cannot be detected with scalp EEG. This higher frequency band is more focal and could lead to more precise and accurate BCIs than EEG methods could ever deliver.

FUNCTIONAL BRAIN MAPPING SOLUTION

cortiQ is a new way of brain mapping for the operating room and neuro monitoring unit that is used with epilepsy or brain tumor patients. cortiQ determines functional areas as those whose electrocorticographic (ECoG) activity increases with tasks such as motor movement or speech production. cortiQ allows neurologists and neurosurgeons to localize eloquent brain areas and provides additional information for surgical resection with a low risk of neurological deficits. cortiQ software can readily be used in addition to traditional mapping procedures such as electrical cortical stimulation (ECS) mapping or fMRI.

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FUSIFORM FACE AREA

High-gamma activity allows doctors to map the temporal base of the cortex. This is useful to find the fusiform face area, an area responsible to identifying faces, and nearby regions responsible for coding colors, shapes, characters, etc. This region can also be used for real-time decoding. In this example, Dr. Ogawa (Asahikawa Medical University Japan) shows different faces, Kanji characters and Arabic characters to the patient with the ECoG implant (high-resolution ECoG on the temporal base on the left and right hemispheres).

The patient just observes the images, and the BCI system decodes high-gamma activity from the ECoG electrodes. The BCI is thereby able to identify which image the patient is seeing in real-time. This worked whether the patient saw other people’s real faces or his own face in the mirror.

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CORTICO-CORTICAL EVOKED POTENTIALS

To record CCEPs, subdural ECoG grids are implanted directly on the cortex on the dominant hemisphere. Then, conventional electrical cortical stimulation mapping is used to identify e.g. Broca’s area. Next, a bipolar stimulation is performed on Broca’s area, which elicits CCEPs over the motor cortex and over the auditory cortex. Electrode channels showing an EP over the motor cortex indicate the mouth region required to say words and sentences.

EPs over the auditory cortex indicate electrode positions representing the regions responsible for hearing and for understanding speech (Wernicke’s area, receptive language area). Overall, the CCEP procedures allow doctors to rapidly map out a whole functional cortical network, which provides important information for neuro-surgical and BCI applications. g.tec offers the cortiQ cortical electrode, the g.HIamp ECoG amplifier and the g.ESTIM PRO- the perfect combination to run CCEP mappings with the g.tec Suite 2020.

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RECORD HIGH-GAMMA UP TO 1 kHz

Clinical recording systems often have a limited sampling frequency and thus can’t reliably record frequencies above 80 Hz. This limits all the neuroscience and BCI experiments and developments to a frequency range from DC to 80 Hz. But we learned from experiments with g.HIamp that high-gamma activity goes all the way up to even 1 kHz! The g.HIamp is the only amplifier on the market that can actually register this tiny activity. This is possible because it performs a very high-oversampling, has a very steep anti-aliasing filter, has high quality amplifiers, can sample very high, has 24 BIT ADCs for each channel and has an input range from DC-6.8 kHz (almost 100 times wider). Never lose high-gamma components in your experiments just because you used the wrong equipment. Patients’ time is too valuable to waste, and so is yours.

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