Attention is a fundamental brain function involving alertness, orientation, and sustained focus. While traditionally measured using complex, multi-channel EEG systems, we have developed simple, real-time markers that capture these processes using a single prefrontal channel. These practical tools enable rapid assessment of cognitive and emotional states and are now being applied in clinical, educational, and research settings worldwide.
We can talk on an attention spectrum, including alertness, orientation and sustained attention
Attention could be viewed as a global increase in activation of brain modules. This global increase promotes general activity in these brain modules, and then activations of specific perceptions and actions may be evoked, in the various brain modules, on the basis of the specific stimuli to which we are exposed, and the associations that our brain has learned. Without this global increase in activation, that we may term attention, the relevant perceptions and actions, in various brain modules, may not reach the activation threshold.
This multi-brain-module increase in activation, which we term attention, is embodied by several distinct brain mechanisms. For applicative purposes we find it useful to follow Posner’s long-standing distinction among three embodiments of such attentional processes: (1) alertness, (2) orientation and (3) sustained attention. However, we prefer to tune the definition of these processes, in order to use them practically.
Alertness could be viewed as a non-specific global increase in activity, which is impacted by stimuli, or internally evoked brain representations that are of major importance to us. For example, painful stimuli, anxiety, or other causes of great excitation, increase our alertness.
Orientation, or selective attention, could be viewed as a transient (often sub-second) increase in activity of multiple relevant brain modules, involved in the processing of specific stimuli, or internally evoked brain representations, which are of potential importance to us. This transient increase in activity may, or may not, be followed by further attentional allocation and processing.
Sustained attention could be viewed as a lasting (multiple seconds) increase in activity of multiple relevant brain modules involved in the processing of specific stimuli, or internally evoked brain representations that have been designated as important for further processing, beyond orientation.
Vast literature on electrophysiological markers of the attention spectrum, and on clinical deviations
Thousands of studies, and many reviews, have reported EEG markers for attention in general, and specifically for the sub-processes of alertness, orientation and sustained attention. Attention-related markers are known to deviate from the normal range in multiple disorders. They tend to be very low in stroke, traumatic brain injury, encephalitis, encephalopathy and seizures. They also tend to be low in ADHD, dementia, depression and schizophrenia. They tend to be high in anxiety and pain.
Most markers are cumbersome to extract. We have developed single channel real-time markers
However, the prevailing markers, which are reported in the literature, often involve multiple EEG channels, which take time to apply, and also long sampling times, in the scale of several minutes for obtaining one marker value. This renders them somewhat cumbersome for routine daily use by most potential users, who were not trained as EEG technicians.
We have developed and validated real-time one-channel markers for the three attentional processes
As the attention-related processes involve multiple brain modules, their electrophysiological manifestations are spread over the cortex. When we look at the multi-channel EEG signals, we can see the strong synchronization among channels. If-fact, the synchronization is easily noted, and it is often more challenging to detect consistent differences among the channels. Therefore, as they are spread and synchronized across channels, and emerge from the activity of multiple brain modules, attention-related electrophysiological markers are measurable from single channels, without significant loss of information (Shahaf, et al., 2015. Comprehensive analysis suggests simple processes underlying EEG/ERP–demonstration with the go/no-go paradigm in ADHD. Journal of Neuroscience Methods, 239, 183-193).
We developed markers, which are measured conveniently in real-time from a single channel at the pre-frontal region, from a wearable headset below the hairline, for the three attention sub-processes – alertness, orientation and sustained attention.
Our markers have been validated in samples from thousands and multiple clinical populations
(partial list, see relevant publications below:)
Currently, we enable researchers worldwide to use our markers for free, and multiple studies are being published independently by other research groups.
Deviations in sustained attention markers indicate two types of barriers to cognitive effort
Deviating sustained attention indicates a barrier to the allocation of cognitive effort. We use the cognitive effort index (CEI) to monitor sustained attention. We identify automatically two types of barriers to sustained attention and engagement in cognitive effort: (1) cognitive barriers, and (2) emotional/affective barriers. Cognitive barriers are identified, by the CEI monitor, when the values are rather consistently below the low threshold. Affective barriers are identified, by the monitor, when the values of the marker are changed sharply either to below the low threshold (an avoidance pattern), or to above the high threshold (an anxious pattern, in which intense attention is directed to the stressor). When the values of the marker are rather consistently in the middle range, between the low and high thresholds, the sustained attention is considered effective (no barrier) (Gvion and Shahaf. 2023. Real-time monitoring of barriers to patient engagement for improved rehabilitation: a protocol and representative case reports. Disability and Rehabilitation: Assistive Technology, 18(6), 849-861).
Reduced orientation markers indicate severe brain dysfunction (encephalopathy)
Even when the level of consciousness is reduced, e.g. due to a disorder of consciousness or due to anesthesia, the brain continues to orient to strong external stimuli, but does not tend to continue with their processing thereafter, as the allocation of sustained attention is reduced. In such conditions, the sustained attention marker (CEI) will be low, but the orientation marker will not be significantly reduced (Baron Shahaf, et al., 2020. The effects of anesthetics on the cortex—lessons from event-related potentials. Frontiers in Systems Neuroscience, 14, 2). If the orientation marker is also reduced, it may indicate severe brain dysfunction, or encephalopathy (Baron Shahaf et al., 2023. Association between risk of stroke and delirium after cardiac surgery and a new electroencephalogram index of interhemispheric similarity. Journal of cardiothoracic and vascular anesthesia, 37(9), 1691-1699). We use the brain reactivity index (BRI) to monitor orientation in such conditions of reduced consciousness.
Deviating alertness markers indicate changes in stress response
Increased alertness may indicate stress. Reduced alertness may indicate relaxation, and if during a task, which might be subjectively threatening, it may indicate dissociation. We use the tension index (TensI) to monitor alertness (Baron Shahaf et al., 2024. Markers of too little effort or too much alertness during neuropsychological assessment: Demonstration with perioperative changes. Brain and Behavior, 14(8), e3649).
This trio of easy-to-use, real-time, markers of attention-related processes, CEI, BRI and TensI, enables us to develop tools and services for various important uses – both clinical and non-clinical. We work on a range of projects for developing such tools and services in multiple areas, including: monitoring to avoid and treat complications in the various intensive care units (ICU), starting from the neonatal ICU; monitoring to avoid and treat complications in the operating room during surgery and anesthesia, and in the peri-operative period; assisting the efficacy of treatment and directing treatment for various neurological and psychiatric disorders; rehabilitation of multiple conditions – including physical rehabilitation (physiotherapy), cognitive rehabilitation, speech rehabilitation, rehabilitation of disorders of consciousness, and rehabilitation of patients with chronic pain; there are also non-clinical, or para-clinical fields in which we are active – such as education and problem solving. We find this wide range of projects to be useful, as insights gained in one field could often be applied in other fields.
Our work in the various fields is based on collaborations with leading clinicians and researchers. We are always happy to expand our collaborations for the development of important applications. We also encourage researchers to use our markers independently, for free, according to their own interest. A continuously growing number of studies are led and published independently by other researchers who use our tools.
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