Electroencephalography (EEG) technology offers a window into the brain's intricate electrical activities, revealing insights into our mental states, emotions, and cognitive processes. Naxon of Labs has been working with this technology through the Muse headband, a portable EEG device, to gather valuable neuronal information. We will explore the details and the rationale behind the strategic placement of sensors on the Muse headband, which is instrumental in the functionality of our Naxon Explorer and Naxon Emotions platforms. We will provide a basic introduction to system 10-20 and system 10-10, as with the new approach of Naxon Labs we will be able to work in software for any EEG system. Finally, we provide a summary of the placement of sensors in the Neuphony device, another partner with whom we are working with.

 

By Olivia Fox

BSci Biological Sciences at University of Birmingham

 

International 10–20 system

The 10-20 System is named for the method of determining electrode locations based on percentages of the distance across the skull. This ensures that electrodes are systematically placed at either 10% or 20% intervals of the total front-back or right-left distance of the head. This methodical approach allows for the detailed mapping of the brain's electrical activity during different states such as sleep and wakefulness. These measurements begin at key anatomical landmarks like the nasion (the area just above the bridge of the nose) and the inion (the highest point of the skull at the back).

Electrodes in the 10-20 System are labeled according to the brain region they cover, with letters representing different areas (Fp for pre-frontal, F for frontal, T for temporal, P for parietal, O for occipital, and C for central). Additional labels include "Z" for midline electrodes, odd numbers for electrodes on the left side of the head, even numbers for those on the right, and "A" or "M" for those placed near the mastoid process behind the ear.

The positioning and labeling of electrodes are critical for interpreting EEG data accurately. For instance, the TP9 and TP10 sensors on the Muse headband correspond to the temporal regions, crucial for emotional processing, while AF7 and AF8 cover the prefrontal cortex, important for emotion regulation. This alignment with the 10-20 System ensures that data collected from the Muse headband can be integrated and compared with broader EEG research and applications.

Understanding the 10-20 System's intricacies, including measurements from nasion to inion and preauricular points, and the specific placement of electrodes around the skull, enhances our ability to capture and analyze brain activity reliably. This knowledge base supports the effective use of EEG technology in both clinical and research settings, providing a foundation for advancements in neuroscience and neurotechnology.

Figure 1: International 10–20 system

The Muse headband is equipped with four primary sensors, thoughtfully positioned to optimize the monitoring of various brain activities. These sensors detect the electrical signals generated by thoughts, emotions, actions, and reactions, enabling the analysis of brainwave patterns that correspond to different mental states such as relaxation, concentration, and emotional responses. Here's an in-depth look at the sensor positions and their importance:

1. TP9 and TP10: Temporal Lobes

Location: Just behind the ears, covering the left and right temporal lobes.
Importance: The temporal lobes are vital for emotional processing, including the interpretation of emotional speech cues, recognition of facial expressions, and formation of emotional memories. Sensors TP9 and TP10 help capture brain responses to emotional stimuli, offering insights into how emotional content is processed, whether through auditory or visual cues.

2. AF7 and AF8: Prefrontal Cortex

Location: On the forehead, adjacent to the hairline, situated over the prefrontal cortex on both sides.
Importance: The prefrontal cortex is key to regulating and controlling emotions. The data from sensors AF7 and AF8 shed light on emotional regulation processes, revealing the mechanisms of emotion expression and management.

 

Higher resolution with System 10-10

For applications requiring more detailed brain activity mapping, the 10-10 system offers a higher resolution extension of the traditional 10-20 system, doubling the number of electrodes to capture more nuanced electrical patterns of the brain. This enhancement allows for a more granular analysis of cerebral functions and disorders, bridging the gap between broad regional monitoring and specific neural pathway observations.

In the 10-10 system, electrode placements are refined using a 10% division scale to introduce intermediate sites between the established 10-20 system locations. This denser grid enables a more precise localization of brain activity, essential for advanced research studies, detailed clinical diagnostics, and neurofeedback applications. The Modified Combinatorial Nomenclature (MCN) introduces additional labeling for these new intermediate positions, expanding the vocabulary of electrode sites.

Figure 2: 10–10 system

The MCN employs numerical designations (1, 3, 5, 7, 9) to denote percentages of distance across the left hemisphere from the inion to the nasion, adding specificity to the electrode's scalp location. New alphabetic codes delineate areas between traditional 10-20 sites, offering insights into regions previously generalized in broader categories:

AF (Anterior Frontal): Situated between the prefrontal (Fp) and frontal (F) regions, providing insights into prefrontal cortex activities that underpin decision-making, social behavior, and personality.
FC (Fronto-Central): Located between the frontal (F) and central (C) areas, crucial for motor function control and higher cognitive processes.
FT (Fronto-Temporal): Bridges the frontal (F) and temporal (T) regions, key for understanding the integration of auditory information and language processing.
CP (Centro-Parietal): Nestled between central (C) and parietal (P) lobes, significant for sensory integration and spatial orientation.
TP (Temporo-Parietal): Between temporal (T) and parietal (P) lobes, important for auditory perception, language comprehension, and social cognition.
PO (Parieto-Occipital): Lies between parietal (P) and occipital (O) regions, essential for visual processing integration.
Additionally, the MCN revises the labeling of some electrodes to align with this expanded framework, renaming T3 to T7, T4 to T8, T5 to P7, and T6 to P8, thereby enhancing the specificity of temporal and parietal monitoring.

For even more detailed brain activity analysis, a "5% system" or "10-5 system" has been proposed, further increasing the number of electrodes and potentially offering unprecedented insights into the brain's electrical dynamics. This evolution in EEG electrode placement systems underscores the continual advancement in neurotechnology, striving for a deeper understanding of the brain's complex workings.

Naxon Explorer is an affordable, useful tool and neurofeedback system for researchers in Neuroscience, Psychology, Medicine, Engineering and Information Technology. It is a web platform dedicated to exploring brain data taken with portable electroencephalographs (portable EEGs from Interaxon – Muse devices), where both an experienced researcher or recently graduated professional can easily explore the brain.

Figure 3: Muse II EEG device from Interaxon

 

The central part of the platform is displayed where you visualize brain wave data in real time on a graph of voltage and time, divided by channel.

Figure 4: Naxon Explorer output for Muse devices

 

Naxon Emotions is a tool to objectively measure and record a person's emotions and cognitive states in real time and at low cost using portable electroencephalography (EEG) headbands.

This real-time emotion recognition system is based on neurophysiological data from EEG, cloud computing and AI.

Measuring concentration and alertness: Naxon Emotions can be used to measure and record in real time the state of concentration and alertness of a person. This record can be viewed on the platform or downloaded in an Excel format for further analysis with other tools.

The possibilities of using these records are multiple, such as providing support and brain correlates to psychometric measures, evaluating clinical interventions, conducting field research in the area of neuromarketing, among others.

 

Figure 5 : Naxon Emotions output using Muse devices

The Neuphony Desktop Application integrates seamlessly with Neuphony's EEG devices, utilizing electrode placements that are pivotal for analyzing brainwave data effectively. Focusing on electrodes Fp1, Fp2, F3, F4, Fz, and Pz, this application leverages the strategic positioning of these sensors to capture detailed neurological activity and cognitive states, offering a comprehensive view of an individual's cognitive health.

 

Electrode Placement and Functionality:

Fp1 and Fp2 (Pre-frontal): Positioned on the forehead, these electrodes monitor the prefrontal cortex, a region associated with higher cognitive functions, decision-making, and personality. This area's activity is crucial for understanding cognitive states such as concentration and stress levels.

F3 and F4 (Frontal): Located on the frontal lobe, these electrodes are essential for assessing cognitive processes related to problem-solving, emotion, and motor function. The frontal lobe plays a significant role in emotional regulation, making these electrodes valuable for studies on mood and affective states.

Fz (Frontal Midline): This electrode, positioned at the midline of the frontal lobe, is instrumental in capturing symmetrical brain activity related to cognitive load and attention. It provides balanced insights into frontal lobe dynamics, essential for tasks requiring concentration and focus.

Pz (Parietal Midline): Situated at the midline of the parietal lobe, Pz is crucial for processing sensory information and spatial orientation. This electrode's data contribute to understanding how individuals interact with and perceive their environment, influencing cognitive functions like navigation and manipulation of objects.

 

Utilizing Electrode Data for Cognitive Insights:

The Neuphony Desktop Application harnesses the data from these electrodes to offer real-time EEG monitoring and cognitive insights. By analyzing band power across different brain regions, the application can discern patterns related to focus, relaxation, vigilance, and mental fatigue. This is particularly valuable in wellness centers and research settings where understanding the nuances of cognitive states can enhance therapeutic interventions or scientific studies.

 

Advanced Features for In-depth Analysis:

Import/Export of .edf Files: Allows for the integration of brainwave data into broader research frameworks, facilitating longitudinal studies and cross-session analyses.
Multiple Experiment Support: Enables diverse studies, from cognitive response tests to sensory processing, leveraging the specific electrode placements for targeted insights.
Session Playback and Band Power Analysis: Offers the ability to revisit recorded sessions for detailed examination and understand the spectral content of brainwaves, which is pivotal for recognizing patterns associated with various cognitive states.
Real-Time EEG and Cognitive Insights: Provides immediate feedback on neurological activity, enabling dynamic adjustments in therapeutic or research protocols based on observed brainwave patterns.
The Neuphony Desktop Application, coupled with strategic electrode placements, represents a powerful tool for advancing our understanding of the brain's intricate workings. By focusing on key areas like the pre-frontal and frontal lobes, and employing advanced analysis features, Neuphony opens up new possibilities for cognitive health research and wellness applications.

 

Figure 6: Electrodes in Neuphony devices

 

References:

10–20 system (EEG) https://en.wikipedia.org/wiki/10%E2%80%9320_system_(EEG)

Visualizing brain wave data in real time https://naxonlabs.com/blog/visualizing-brain-wave-data-in-real-time

Measuring concentration and alertness with Naxon Emotions https://naxonlabs.com/blog/measuring-concentration-and-alertness-with-naxon-emotions

Analyzing Brainwaves Data with Neuphony Desktop Application https://naxonlabs.com/blog/analyzing-brainwaves-data-neuphony-desktop-application