Submitted:
05 November 2024
Posted:
06 November 2024
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Abstract
The pursuit of understanding the brain’s complex mechanisms is at the forefront of neuroscience, especially in developing early diagnostic tools for neurological diseases. Advances in neural fields, brain dynamics, and the integration of applied physics have opened new possibilities for identifying biomarkers indicative of neurological conditions such as Alzheimer’s disease, schizophrenia, and ADHD. Each of these fields contributes uniquely: neural fields offer a spatially distributed model of brain activity, brain dynamics provide insights into temporal patterns and oscillations, and applied surface physics enhances the precision of neural interface technologies and imaging. Combined, they form a multidisciplinary foundation that allows researchers to study the brain’s intricate structures and functions with unprecedented clarity, revealing potential pathways for diagnosing and treating neurological disorders.
Keywords:
1. Introduction
1.1. Neural Fields: Mapping Brain Activity in Space
1.2. Mathematical Models in Neural Field Theory
1.3. Brain Dynamics: Temporal Patterns and Oscillations
1.3.1. Oscillatory Activity as a Diagnostic Tool
1.3.2. Noise and Stochasticity in Brain Dynamics
1.4. Neurological Disease Biomarkers: From Theory to Clinical Application
1.4.1. EEG Biomarkers in Neurological Disorders
1.4.2. Biomarkers in Alzheimer’s Disease
1.5. Applied Surface Physics in Neurology
1.5.1. Enhancing Neural Data Accuracy with Surface Physics
1.6. Topological Data Analysis (TDA) in Brain Mapping
1.7.1. Conclusion
2. Methodology
2.1. Neural Field Theory
- : neural activity at position and time ,
- : synaptic weight or connectivity function describing the strength of interaction between neurons at and ,
- : nonlinear activation function, often chosen as a sigmoid or threshold function to model neural firing responses,
- : external input to the network, which could represent sensory input or stimulation.
2.1.1. Connectivity Function
- : amplitude parameters for excitation and inhibition,
- : spatial scales for excitation and inhibition, respectively.
2.2. Stochastic Dynamics for Brain Oscillations
- : amplitude of the noise, which can vary spatially and temporally,
- : Wiener process (or white noise), representing random fluctuations in neural activity.
2.2.1. Mean Field Analysis of Oscillatory Activity
2.3. Signal Processing and Surface Physics for Neural Interfaces
2.3.1. Laplace Surface Filtering for EEG Signals
- : potential at the primary electrode location,
- : potentials at neighbouring electrodes surrounding .
2.4. Topological Data Analysis (TDA) on Surface Maps
2.5. Model Validation and Biomarker Extraction
2.6. Electrodynamics and Maxwell's Equations in Neural Modelling
2.7. Quasi-Static Approximation for EEG Signal Modelling
2.8. Cross-Correlation for Synchrony Detection
Conclusion
2.9. Computational Methods
-
Neural Field Dynamics:
- o
- A Gaussian connectivity function models localized neural interactions, promoting nearby excitation and distant inhibition.
- o
- External input III is added at specific locations to simulate stimulus.
- o
- Neural field dynamics are updated iteratively, including a tanh nonlinearity to simulate neuron firing and Gaussian noise to model stochastic effects.
-
EEG Signal Calculation:
- o
- EEG signals are approximated by summing local neural activity around specific electrode positions, capturing nearby electric potentials in the field.
-
Visualization:
- o
- Neural Field Activity Over Time: A heatmap showing the spatial-temporal evolution of neural activity.
- o
- Simulated EEG Signals: EEG signals at each electrode position over time.
- o
- Power Spectral Density (PSD): Frequency-domain representation of EEG signals, showing power distribution across different frequencies.
3. Results and Discusion
3.1. Neural Activity Propagation:
- o The heatmap of neural field activity illustrates how an initial external stimulus (applied between positions 40 and 60) propagates through the field. The spatial spread is influenced by the connectivity function w(x,y), with neighboring regions showing synchronized activity.

3.2. Magnetic Potential Influence
- o The magnetic potential heatmap (Figure 2) shows a clear interaction between neural activity and the generated magnetic fields. The magnetic field acts as feedback, altering the neural activity in subsequent time steps, which reflects the bidirectional coupling between electrical and magnetic components in the model.
3.3. EEG Signals
- o The simulated EEG signals reflect the local neural dynamics around each electrode. Differences between signals at different electrode positions highlight how spatial variations in connectivity and external inputs lead to different patterns of neural activity.
3.4. Frequency Analysis (PSD):
- o The PSD show the frequency components present in the EEG signals. Peaks at certain frequencies indicate rhythmic neural activity, which could be indicative of underlying brain states such as relaxation (alpha waves) or cognitive engagement (beta waves).
3.4.1. Functional Connectivity (Cross-Correlation)
- o Cross-correlation between EEG signals provides insights into the temporal relationships between different parts of the neural field. High correlations indicate synchronized activity, potentially pointing to functional connectivity. Synchronization between electrodes might signify coordinated neural processes or pathological synchrony (as seen in epileptic seizures).

Conclusion
3.5. Implications for Biomarker Identification
- Amplitude of Neural Activity: The level of activity in response to stimuli may indicate neural tissue excitability, a characteristic associated with epilepsy and other hyper-excitability conditions (Crunelli & Leresche, 2002).
- Oscillatory Patterns: Distinct frequency components of EEG signals, as shown in PSD plots, can help identify specific cognitive or pathological states. For instance, reduced beta and elevated theta power often correlate with attentional deficits, suggesting potential biomarkers for ADHD (Barry et al., 2003).
- Functional Connectivity: Cross-correlation provides insights into synchronisation patterns, which are altered in various neurological and psychiatric disorders. For example, functional disconnection in schizophrenia is marked by decreased synchronisation in gamma oscillations (Uhlhaas & Singer, 2010).
Limitations and Future Directions
4. Conclusion
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