fNIRS

Brief overview of the modality

The functional near infrared (fNIRS) laboratory houses the Imagent (v2) system. The Imagent system is based on the measurement of the propagation of near infrared light through tissue, allowing for non-invasive functional imaging of the brain. The Imagent system is a time resolved fNIRS system that measures the light intensity, the modulation of the light and the time taken by the light signal to traverse the illuminated area of the brain (or other targeted tissue).

This imaging technology together with model-based image reconstruction techniques (e.g. NIRFAST) provide a balance between temporal and spatial resolution for the study of superficially located areas of the human brain (typically up to 30 mm deep from the scalp). This imaging approach is able to detect variations in the blood oxygenation levels of activated brain areas and provide spatial maps of where these haemodynamic changes occur, thus combining the fast neurological signals (the event related  optical signal) and the slow signals (haemodynamic changes) of the brain.  The Imagent system features 64 emitters and 30 detectors, which provides 960 optical channels and has the capability of simultaneous whole-head imaging.

The system can be combined with EEG, TMS and MRI operations, as well as used in conjunction with typical stimulus-response tools to assess brain health (e.g. button boxes, cerebrovascular reactivity protocols). 

The CHBH also has several off-the-shelf commercially available continuous wave NIRS systems (e.g. NIRO 200NX, INVOS) that support numerous projects taking place across campus by members of our group (e.g. Lucas, Dehghani, Belli). These systems are portable and suitable for experimental and clinical-based work.

How researchers can access equipment within modality?

To gain access on the Imagent fNIRS system there is are procedures for training, ethics and project proposals. For the procedures please see the CHBH Operating Procedures and Local Rules.

What research data is produced and what can we understand from this?

This imaging approach is able to detect variations in the blood oxygenation levels of activated brain areas and provide spatial maps of where these haemodynamic changes occur, thus combining the fast neurological signals (the event related optical signal) and the slow signals (haemodynamic changes) of the brain. 

How is the modality important in contributing to the CHBH values and principles?

The Imagent fNIRS system is used for conducting fundamental research on cerebral haemodynamics and its coupling to neuronal activity (i.e. neurovascular coupling), as well as to investigate brain vascular health and disease. The data from the fNIRS system are complementary to data from other techniques housed in the CHBH.  Therefore, we are integrating the fNIRS research using other techniques as for instance functional MRI and transcranial Doppler imaging, and in combination with brain stimulation techniques. The research conducted on the Imagent system is done is spirit of open science and we strive to co-register new studies and make our approaches and data freely available.