Publication overview 2024 - fNIRS studies with our devices
We are happy to share, that in 2024 an increased number of papers were published using our devices to measure brain activity. In this blogpost, we will explain various research fields where our (f)NIRS devices found application in the last year, and highlight outstanding publications per category. Further, we will showcase exciting research done in the last year using our devices in naturalistic settings outside of the lab.
With functional Near-Infrared Spectroscopy (fNIRS), we can measure brain activity by acquiring relative concentration changes in oxygenated hemoglobin (O2Hb) and deoxygenated hemoglobin (HHb) locally from any cortical brain region. It is non-invasive, easy to use, often portable and relatively insensitive to motion artifacts. Thanks to these technological and methodological advantages, fNIRS can be used across various application fields, and in participants of all ages, sexes, and conditions.
We are proud that our devices were used across various research areas, leading to many new and exciting publications, in common, as well as novel fNIRS applications. An overview of distribution of applications can be found in Figure 1. We are delighted to see that compared to previous years, the number of studies in 2024 has increased in all categories, in most it even doubled (see Figure 2).
Application Areas using Artinis fNIRS devices in 2024
Comparison of fNIRS publications per category in the last years
In the following, we will introduce research areas that our devices were used in last year, and highlight exciting studies published in 2024 per category.
Brain Function - Prefrontal Cortex
In 2024, 114 papers using our devices measuring brain function in the prefrontal cortex (PFC) were identified. The PFC is involved in a variety of functions such as attention, execution of actions, impulse control, coordination and planning. To measure fNIRS in the PFC, researchers used both our devices specifically designed for frontal areas, such as Brite Frontal, or devices that can be used to measure from any cortical region (see Figure 3).
Artinis fNIRS devices used in prefrontal studies 2024
Cognitive Neuroscience
Cognition is a term used to describe mental processes in the brain, such as learning, memory or attention. In 2024, 114 cognitive studies using our devices were published across a huge range of applications, for instance to assess cognitive / mental load in subjects of all ages.
To this end, Gonzalez et al. examined the effects of cognitive load on brain-behavior relationship in young and elderly subjects applying multivariate partial least square analysis of fNIRS data. Participants performed single and dual 2-back tasks while the Brite was used to measure prefrontal activity. Findings provide important insights in neurocognitive aging patterns by demonstrating that brain-behavior relationships are variable and complex, and emphasize the need to consider task complexity and cognitive demands for age-related brain activity analysis.
In another application, fNIRS is applied in cognitive neuroscience to study the effects of intervention, such as training or exercise, on cognitive performance. Best et al. investigated whether polyphenolic rich supplement can improve cognitive performance. Participants were randomly divided into a control or placebo group and cognition and brain activity were measured using fNIRS and 2-back task before, 28 days after intervention and 14 days after wash-out. The supplement enhanced cognitive performance and prefrontal brain activity in the intervention compared to the control group after intervention and follow-up.
Applied Neuroscience
In 2024 various studies using our devices in applied neuroscience, for instance environmental, societal or economic studies, were published. Zhang et al. performed a study measuring fNIRS in the prefrontal cortex during 14 types of highly automated driving scenarios to assess driving risk cognition, considering various factors such as age, sex and driving experience. The fNIRS data set was successfully used to distinguish the driving risk in highly automated scenarios using brain-computer interface, and further enabled prevention of potential hazard before its occurrence in certain scenarios.
Brain Function - Others
Despite the prefrontal cortex being the most frequently measured brain area, fNIRS can be applied on any cortical region, including the motor, temporal or parietal cortices. In 2024, 26 papers that measured cortical activity in brain regions other than the frontal cortex could be identified. As shown in Figure 4, the most used device was the Brite, which can even measure from various cortical regions at the same time.
Artinis fNIRS devices used in other brain regions 2024
As an example, Jalalvandi et al. performed a study combining fNIRS and fMRI to gain further insights intocomplex brain activation patterns during motor tasks. fNIRS and fMRI were measured simultaneously in the motor and somatosensory cortex during wrist movement. Results demonstrate a strong correlation of fNIRS and fMRI, as well as fNIRS being an effective tool to detect brain activation during motor tasks. This suggests that fNIRS can be used as a reliable method in subjects that are unable to undergo fMRI scans.
Artinis fNIRS devices used in clinical publications 2024
Clinical & Rehabilitation
Due to its technical advantages, such as non-invasiveness, portability, comfort, and ease of use, fNIRS is a technique that is increasingly used to study brain activity in clinical populations. Last year, 52 papers using our fNIRS devices in medical fields, such as neurology, psychiatry and gerontology, were published. Especially our portable devices, such as the Brite and PortaLite, are frequently used, to enable comfort and freedom of movement, especially in sensitive subjects / patients, as shown in Figure 5.
In clinical settings, fNIRS is frequently used to test its potential as (adjunct) diagnostic tool in various neurological and psychiatric diseases. Guevara et al. performed a study to investigate the potential of fNIRS as an adjunct diagnostic tool in patients with Parkinson’s Disease (PD) using machine learning. Various features were extracted from the fNIRS data recorded with the Brite and tests were performed to identify the best implementation. The best approach, which included 14 features, reached an accuracy and precision of 100% and area under the curve of 1, demonstrating the potential to integrate fNIRS and machine learning in the detection of PD.
Further, in clinical research, fNIRS can be applied to assess the effectiveness of therapy strategies in patients with various disorders. Beretta et al. investigated the effect of multiple (8) sessions of tDCS on postural responses of PD patients. fNIRS was measured before, 48 hours after and 1 month after intervention. The results, which showed a decrease in prefrontal activity in patients receiving tCS compared to the sham control, demonstrated improvement in postural responses and movement automaticity, even one month after stimulation. Bassi et al. assessed whether phrenic nerve stimulation could improve neural activity and connectivity in deeply sedated and ventilated patients with acute respiratory distress syndrome. Simultaneous fNIRS-EEG recordings using Brite and SAGA were performed. Results showed that phrenic nerve stimulation led to increased neural activity, connectivity and synchronization in the frontal, temporal and parietal cortices.
Sports Science
Sport performance and movement does not only affect muscle strength, but can also influence neural, such as cognitive or executive functions. Hence, measuring brain activity during or after exercise can give valuable insights into neural components and effectiveness of their improvement / therapy strategies. In 2024, 24 studies using fNIRS in sports science were published. fNIRS devices, such as the PortaLite or Brite (see Figure 6), are often completely portable and relatively insensitive to motion artifacts, making them perfect tools to measure neural activity in sports science studies.
Artinis fNIRS devices used in Sports Science publications in 2024
Hong et al. assessed the effect of different physical exercise loads and intake of hydrogen gas (H2) on prefrontal oxygenation using fNIRS. The Brite was used to measure brain activity in the prefrontal cortex during endurance cycling exercise at 0-100 % physical load, while participants received either H2 or placebo prior to exercise. Significant differences in prefrontal oxygenation between different levels of physical load could and H2 vs placebo were found, suggesting that fNIRS is a suitable tool to measure adaptive changes in the frontal cortex and interventions during endurance exercise.
Multimodality
Combining fNIRS with other modalities, such as EEG and tCS, is increasingly used in many application fields, as it can help to achieve a complete picture of brain activity in various applications. Our Brite and Brite Lite devices for instance, can be almost completely integrated with mobile EEG solutions such as APEX and SAGA, enabling a wearable and still comfortable setup with increased measurement options. In 2024, 18 studies using fNIRS in combination with other neuroimaging techniques could be found.
Naik et al. performed a study to develop and test a multimodal machine learning approach to classify cognitive workload during surgery. Surgical trainees conducted laparoscopic surgery with increasing difficulty, and physiological parameters, including simultaneous measurement of fNIRS-EEG with the Brite and SAGA were measured. Perceived cognitive load could be correctly classified using the machine learning approach, which opens the door for using cognitive workload assessment during surgical training in the future.
fNIRS can also be perfectly combined with various non-invasive brain stimulation methods, including TMS or tDCS, as it does not interfere with neurostimulation techniques and can even be combined on one headcap to measure simultaneously. In 2024, various papers combining fNIRS with tDCS were published in both neuroscience and clinical studies, to assess the potential of neurostimulation to improve brain function in healthy and clinical population.
Panico et al. investigated the influence of the functional cerebello-frontal network on the recognition of emotional prosody. In different sessions, transcranial current stimulation (tCS) over the cerebellum or sham control was applied, while neural activity was measured with fNIRS on the frontal cortex during a vocal recognition task. tCS was shown to reduce brain activity, while test accuracy and reaction time remained unchanged. This indicates cerebello-frontal connection and effectiveness of cerebellar brain stimulation.
Virtual Reality
Due to its portability and wearability, fNIRS can be used in combination with Virtual Reality (VR), as it still allows for participants to freely wander in virtual worlds. VR is frequently used as it enables creation of real-world scenarios to measure human behavior in naturalistic settings. Furthermore, VR offers the possibility to provide cognitive training, and fNIRS can be used to assess or guide training effects.
To this end, Park performed a study to examine whether VR-based cognitive training in parallel with fNIRS-derived neurofeedback can enhance cognitive and neural functions in subjects with mild-cognitive impairment (MCI). The active group that received VR-training and fNIRS neurofeedback showed greater improvement and lower prefrontal brain activity compared to control groups. This indicates the effectiveness of combining VR and fNIRS neurofeedback to enhance cognitive functions in subjects with MCI.
Hyperscanning
Hyperscanning describes the recording of brain activity of multiple subjects simultaneously. Its technical advantages (i.e. portability, ease of use) allow fNIRS to be applied in more realistic settings and are increasingly used to assess inter-brain synchrony. As our software solutions enables to connect multiple devices at the same time, hyperscanning and synchronous measurements can easily be performed.
In a study published last year, Pick et al. assessed the effect of group dynamic on creativity. Brain activity from four subjects was measured simultaneously in the prefrontal cortex with the Brite, while subjects performed brainstorming. Increased inter-brain coupling among pairs across regions was detected using fNIRS hyperscanning.
Hypoxia and Altitude
Hypoxia is defined as any condition in which the oxygen demand of a tissue exceeds its supply, leading to oxygen deprivation. Exposure to hypoxia can influence the oxygenation in the brain and can have effects on cognitive performance, for instance. In 2024, six papers using fNIRS to measure brain oxygenation in hypoxic conditions were published.
In a study published in 2024, Goepp et al. assessed whetherhypoxia in combination with performance of a physically demanding motor-dual task can influence cognitive performance. Prefrontal brain activity and other physiological parameters were constantly measured during a cognitive attention task and cycling exercise, while participants were in normoxia or hypoxia. Performance of cognitive task together with cycling exercise showed to impair cognitive accuracy, especially in hypoxic condition compared to normoxic condition.
Studies in naturalistic settings outside of the lab
One of the biggest advantages of fNIRS is its portability, which enables the performance of experiments in any setting, even outside of the lab. We are happy to see that last year many papers using our devices in naturalistic settings during daily activities were published. As one example, Dupuy et al. investigated whether visiting museums can positively affect the well-being of elderly adults while using fNIRS to measure prefrontal activity during artwork analysis. Participants walked freely in the Montreal Museum of Fine Arts while wearing the Brite and were asked to either analyze, or solely visualize paintings. Increased activation in brain areas related to attention was found in the analytic condition, which could predict a decrease in anxiety before and after the visit especially in elderly women. In another study by Zhang et al., they showed that the mental activity of passengers influenced the risk during driving with highly automated vehicles, by performing an experiment during driving on a practice street.
Measuring brain activity outside of the lab can further increase possibilities in the clinical field, for example, by detecting diseases during (long-term) measurements at home. Klop et al., for instance, performed a study to test the feasibility and reliability of using NIRS as a home-based monitoring tool to assess orthostatic hypotension (OH). The PortaLite was used to measure frontal oxygenation for more than 10 hours a day in patients with OH and healthy controls. The study demonstrated the feasibility of using NIRS in home settings, as well as the potential of NIRS to detect OH.
Would you like to learn more about using our devices to measure brain activity? Then feel free to reach out to us at askforinfo@artinis.com.