Let’s rewind and take a look at what 2019 brought us in terms of publications. In 2019, Artinis devices were used in a record number of 256 publications. The OxyMon MKII was used in 83 publications and the PortaLite in 61, making PortaLite the most cited portable brain device in 2019. The OctaMon is also gaining more popularity with 15 citations, and the Brite has already mentioned in 11 papers. We are very proud to see our equipment used in a wide range of scientific research and continue to be inspired by the bright scientists who are our customers. Perhaps the biggest takeaway from all the publications last year is the fact that NIRS is no longer navel-gazing as a research field on its own, but it has reached out and found a new audience as a versatile research application that, even more than fMRI, is being used in more and more parallel fields. Taking a step back, we highlight some of the noteworthy elements of 2019’s publications:

We see the increased use of both PortaLite and OctaMon devices. When we release a device, it’s always exciting to anticipate the possible publications that might come out. However, there’s always a delay between release and publication. Since their release (respectively 2017 and 2018), we now see that research done with both devices is getting the traction in the scientific community that we aim for. Let’s look at some highlights from publications done with our devices:

OxyMon

Gruber et al [1] found that with NIRS, frontal lateralization (specifically in inferior frontal cortices) of human emotion vocalization processing can be studied. They demonstrated the involvement of the right hemisphere to process fear stimuli, and of both hemispheres to treat anger stimuli. They used an OxyMon in an 8 channel configuration to come to this result.

Another study showed that the dorsolateral prefrontal cortex (PFC) is influenced more strongly by postural than cognitive load. Marusic and colleagues[2] investigated younger and older adults with a single channel OxyMon setup to come to this conclusion. Interestingly, they found no significant difference in the cortical activation between the age groups.

Continuing on the PFC subject, Parshi and colleagues [3] investigated mental workload by looking at dynamic functional connectivity patterns. Using support vector machines, they classified data gathered with OxyMon from three different N-back tasks and showed that it is possible to separate the different tasks from the NIRS data without prior assumptions.

In the left frontopolar cortex, Tempest and Radel [4] found that changes in oxygenated hemoglobin were larger and took longer to decline in participants who were cued to think creatively in coming up with an associated verb when presented with a noun. NIRS data correlated with behavioral measures of increased creativity making it a tool to asses creative thinking in future research.

In an effort to examine the effects of chronological age and cardiorespiratory fitness on cognitive performance and prefrontal cortex activity, Agbangla and colleagues [5] tested young (18-22 years) and old (60-77 years) participants who performed a working memory updating task under different cognitive load conditions. They recorded the prefrontal cortex as well as behavioral performance. Their results show that in older adults, higher levels of cardiorespiratory fitness were related to increased bilateral prefrontal cortex activation patterns that allowed them to sustain better cognitive performances.

Not only the frontal cortex is a popular area for fNIRS research, the sensorimotor area also featured in several OxyMon studies. Using transcranial Direct Current Stimulation (tDCS), Muthalib and colleagues [6] simultaneously measured fNIRS and EEG signals. They show that tDCS induced activation can be picked up by fNIRS, using a 16 channel OxyMon setup. Stimulating the left sensorimotor cortex resulted in a greater increase in O2Hb concentration compared to the sham (very weak stimulation or placebo) condition.

PortaLite

Our light and portable cerebral oxygenation measurement device, the PortaLite had a good year. It was used in a wide variety of research topics: to measure cognitive load in control room operators, prefrontal cortex activation in stroke patients, or to measure the relation between frontal lobe perfusion and depressive symptoms in later life.

Zooming in on these stories:

Sturman and colleagues [7] measured cognitive load in control room operators. Their research posed the question whether cue utilization is predictive of an operator’s sustained attention performance during regular operational tasks. Behaviorally, improved cue utilization could not be predicted from eye measurements such as saccade amplitude. However, in cerebral oxygenation measured with the PortaLite on the prefrontal cortex, a difference could be shown. Operators with higher cue utilization experience lower cognitive load,i.e. smaller 02Hb concentration changes.

Not only the OxyMon was used to test whether physical activity and cognitive performance are related. Goenarjo and colleagues [8] used the PortaLite to measure prefrontal cortex and executive function in active and inactive subjects. Using a Stroop task, they found a relation between test scores and physical activity, and between prefrontal activation and physical activity levels. Subjects with a higher level of physical activity had higher levels of oxygenation during the task.

The PortaLite is also used a lot in medical research, for instance with stroke patients. Hermand and colleagues [9] studied stroke patients performing a cognitive task while walking, i.e. a dual-task (DT). Using a paradigm with two N-back tasks with different associated cerebral workloads, the researchers monitored stroke patients who completed a walk. Results showed an increase of O2Hb while walking, which was not augmented by cognitive loads in DT. These data highlight a “ceiling” effect in O2Hb levels while walking, leaving no available resources for simultaneous cognitive tasks, during the early recovery period following stroke. In these patients, cognitive, but not motor, performances declined with a higher cognitive load.

Another medical study involved measuring the Tissue Saturation Index (TSI) in elderly patients with depressive symptoms. Briggs and colleagues [10] found that there was significantly lower TSI in participants with depressive symptoms at both 60 and 90 s post-standing. This finding indicates that lower frontal lobe perfusion, related to lower values of baseline systolic blood pressure might be a cause for depression in the elderly. This might give an indication for possible diagnostic or even preventive assessments for depression in the elderly.

Some final OctaMon and Brite thoughts:

To finish, we would like to point out two publications done with our OctaMon and Brite devices.

Best and colleagues[11] studied the acute effects of combined Bacopa, American ginseng and whole coffee fruit on working memory and the cerebral hemodynamic response of the prefrontal cortex. They found that while doing an N-back task, participants who were given a supplement containing the psychoactive components of the aforementioned foods performed better and had less PFC activation compared to the placebo group. PFC activation was measured with our OctaMon system.

Our Brite system is our newest device, therefore we are just starting to see publications from research done with it. A problem in NIRS measurements is the attenuation of the signal due to the dark skin of subjects. Bronkhorst and colleagues [12] showed the Brite can be used to measure on pigmented subjects as well.

References:

[1] Gruber, T., Debracque, C., Ceravolo, L., Igloi, K., Bosch, B. M., Fruehholz, S., & Grandjean, D. (2019). Human discrimination and categorization of emotions in voices: a functional Near-Infrared Spectroscopy (fNIRS) study. bioRxiv, 526558.

[2] Marusic, U., Taube, W., Morrison, S. A., Biasutti, L., Grassi, B., De Pauw, K., ... & Ruffieux, J. (2019). Aging effects on prefrontal cortex oxygenation in a posture-cognition dual-task: an fNIRS pilot study. European Review of Aging and Physical Activity, 16(1), 1-7.

[3] Parshi, S., Amin, R., Azgomi, H. F., & Faghih, R. T. (2019, May). Mental workload classification via hierarchical latent dictionary learning: A functional near infrared spectroscopy study. In 2019 IEEE EMBS International Conference on Biomedical & Health Informatics (BHI) (pp. 1-4). IEEE.

[4] Tempest, G. D., & Radel, R. (2019). Put on your (fNIRS) thinking cap: Frontopolar activation during augmented state creativity. Behavioural brain research, 373, 112082.

[5] Agbangla, N. F., Audiffren, M., Pylouster, J., & Albinet, C. T. (2019). Working memory, cognitive load and cardiorespiratory fitness: Testing the CRUNCH model with near-infrared spectroscopy. Brain sciences, 9(2), 38.

[6] Muthalib, M., Besson, P., Dutta, A., Hayashibe, M., & Perrey, S. (2019). Neurophysiological Correlates of tDCS-Induced Modulation of Cortical Sensorimotor Networks: A Simultaneous fNIRS–EEG Study. In Neuroergonomics (pp. 147-151). Academic Press.

[7] Sturman, D., Wiggins, M. W., Auton, J., Loft, S., Helton, W., Westbrook, J., & Braithwaite, J. (2019). Control room operators’ cue utilization predicts cognitive resource consumption during regular operational tasks. Frontiers in psychology, 10, 1967.

[8] Goenarjo, R., Bosquet, L., Berryman, N., Metier, V., Perrochon, A., Fraser, S. A., & Dupuy, O. (2020). Cerebral Oxygenation Reserve: The Relationship Between Physical Activity Level and the Cognitive Load During a Stroop Task in Healthy Young Males. International Journal of Environmental Research and Public Health, 17(4), 1406.

[9] Hermand, E., Tapie, B., Dupuy, O., Fraser, S. A., Compagnat, M., Salle, J. Y., ... & Perrochon, A. (2019). Prefrontal cortex activation during dual task with increasing cognitive load in subacute stroke patients: A pilot study. Frontiers in Aging Neuroscience, 11, 160.

 [10] Briggs, R., Carey, D., Claffey, P., McNicholas, T., Newman, L., Nolan, H., ... & Kenny, R. A. (2019). The association between frontal lobe perfusion and depressive symptoms in later life. The British Journal of Psychiatry, 214(4), 230-236.

[11] Best, T., Clarke, C., Nuzum, N., & Teo, W. P. (2019). Acute effects of combined Bacopa, American ginseng and whole coffee fruit on working memory and cerebral haemodynamic response of the prefrontal cortex: a double-blind, placebo-controlled study. Nutritional neuroscience, 1-12.

[12] Bronkhorst, M., Mukisa, R., Colier, W. N., Stothers, L., & Macnab, A. J. (2019, April). Functional near infrared spectroscopy (fNIRS) in pigmented subjects: a maneuver to confirm sufficient transcutaneous photon transmission for measurement of hemodynamic change in the anterior cortex. In Optical Sensors 2019 (Vol. 11028, p. 1102813). International Society for Optics and Photonics.