Nerve communication model by bio-cells and optical dipole coupling effects

Abstract

A novel design of nerve communications and networks using the coupling effects between bio-cells and optical dipoles is proposed. The electrical signals are coupled to the dipoles and cells which propagate within the optical networks for long distance without any electromagnetic interference. Results have shown that the use of optical spins in the spin networks, referred as Spinnet, can be formed. This technique can be used to improve the nerve communication performance. It is fabricated as a nano-biotic circuit system, and has great potential for future disability applications and diagnosis of the links of nerves across the dead cells.

Keywords::

• cell communications
• bioelectronics
• bioinformatics
• nerve communications

Introduction

Communication among cells plays the crucial role in human body mechanism by sending and receiving signals. It conveys information for sensation, feeling, emotion responses, thoughts, learning, memory, cause of mental disorders, and any other function of human brain (Meyl 2012). The nerve cell communication model is shown in Figure 1, where the signals from the surrounding environment or other cells, such as a response trigger signals are communicated across cell membrane. Signal information can cross the membrane through the movement of an electrical impulse and contact both outer and inner sides of the cell that is interacting with receptor proteins (Lee et al. 2010). In this case, the healthy cell receptors will respond to the signal on their surfaces (Kavasseri and Nagarajan 2006). Generally, neuron or nerve cell is the key player in the nervous system activity. Within the neuron, two types of phenomena are involved in nerve impulse process, chemical and electrical phenomenon. There are three main parts of neuron. The first part, dendrites are the thin fibers that extend for a hundreds of micrometers in many branched tendrils. They arise from the cell body to receive information from other neurons. The second part, soma or cell body is the major part for neuron basic cellular functioning. For instance, the soma of a neuron can vary from 4 to 100 μm in diameter. The third part is a long thin fiber called axon which transmits nerve impulses to other neurons (Bennett and Zukin 2004). Neurons are present in many different shapes and sizes and categorized into two types by their function and morphology. Type I have long axons and been used to transmit signals over long distances. The basic morphology, represented by spinal motor neurons, consists of a soma and a long thin axon covered by the myelin sheath. The end of the axon has branching terminals known as axon terminal and is used to release neurotransmitters into a gap called the synaptic cleft between the terminals and the dendrites of the next neuron (4 nm). The adult human brain is estimated to contain from 10¹⁴ to 5 × 10¹⁴ synapses. Around the soma there is a dendrite branching tree that receives signals from other neurons. Type II has short axons, which can be often confused with dendrites. The emergence of structure rhythmic structure contributed different activity in cell communication network (Floresa et al. 2012, Connors and Long 2004).

Figure 1. Nerve cell communication model.

After the discovery of neuronal inhibition in the early 1950s, it was accepted that information transmission via neurotransmitter molecules (chemical synapses) represents the major form of signaling among central nerve system (CNS) neurons. Recently, many observations on cell communication were proposed (Adhikari et al. 2011, Akyildiz and Jornet 2010), in which the developed synthesized electrical synapses were presented in a subset of neuronal connection. The electrical synapses usually show bidirectional transmission, ideal for synchronized behavior in a syncytium and very fast signal transmission, temperature insensitive, excitatory, and limited amplitude about 1 mV (Gibson et al. 2005, Blethyn et al. 2008). The effects of neural activity on the strength of electrical synapses in the mammalian CNS were investigated and presented. Haas et al. (2011) recorded the electrical activity from pairs of neurons in the rat thalamic reticular nucleus (TRN) that affects long-term depression (LTD) in the thalamus of the mammalian brain. All sensory messages are conveyed to the cortex via the thalamus. The bursts of spikes in pairs of coupled TRN neurons resulted in the strength of electrical synapses. The limitation of this investigation is that interference with adjacent cells occurred when coupled between a pair of neural cells. The use of biosensors for diagnosis of diseases, food testing, and the environmental detection of biological agents has increased dramatically over the past few decades. Recently, a fiber-optic localized surface plasmon resonance (FO-LPR) chemical and biochemical sensing platform for label-free and real-time detection has been developed (Zhang et al. 2012, Tian et al. 2011). The unclad section of an optical fiber is modified with self-assembled gold nano-particles which are functionalized with a receptor. The characteristics of gold nano-particles exhibit a strong absorption band that results when the incident photon frequency is in resonance with the conduction electrons oscillation and is known as the localized plasmon resonance (LPR). Targeted signal can be detected or transmitted by gold nano-particles called “gold nano-antenna” (Hsieh et al. 2007).

A new research vision, optical spin, has shown great progress nowadays. The spin mechanism using bright and dark soliton conversion behaviors was successfully demonstrated by Yupapin et al. (2011, 2012), which consists of a modified add-drop optical filter known as “a PANDA ring resonator”. Soliton spins can be decomposed into left and right circularly polarized waves called “a dark-bright soliton pair”. Additionally, the use of a nano-scale device is very important component for a nano regime. In the nano-antenna, surface plasmon resonance (SPR) theory for signal propagation and detection can be formed and used (Seok et al. 2011, Armelles et al. 2008, Fischer and Martin et al. 2008). Moreover, there are many optical spin applications such as high data rate communications (Rakic et al. 1998), monitoring and spectroscopy, medical imaging (Mitatha et al. 2011a), security, material spectroscopy and sensing (Katti et al. 2006), and biology and medicine (Aziz et al. 2012). For the cell-biological scale, optical nano-antenna has dominant features due to its unique features for fabrication and characterization, which covers the potential advantages in the detection of light showing polarization, tunable, targeted cells, and rapid time response. Consequently, this paper demonstrates a neural cell communication model for bio-cell coupling with optical nano-antenna based on PANDA ring resonator to generate the optical spin manipulation. A schematic of nerve communication system design called “Spinnet” will be illustrated in the next section. The results obtained have shown that the spin mechanism using bright and dark soliton conversion increases the electrical coupling efficiency by using optical spin nano-antenna for nerve communication network. In applications, the link between nerves and cells may be useful and realized for brain learning and applying knowledge, neurological disorders, disability therapeutic, and rehabilitation cell disease applications.

Neuron cell model

Fundamental mechanism of signal transmission within neurons is based on potential differences between inner and outer sides of the cell. The membrane potential is produced by the irregular distribution of electrically charged particles, or ions, sodium (Na+), potassium (K+), chloride (Cl‐), and calcium (Ca²⁺) (Li et al. 2009). The voltage difference across the membrane is affected by redistribution of electric charge. Ions or neurotransmitters enter and exit the cell through specific protein channels in the cell's membrane. The cell's membrane potential controls the channel changing for “open” or “close” (Blankenship and Feller 2009). Consequently, an impulse travels to the neuron by decreasing exceeded voltage difference in certain threshold is called depolarization. It occurs when positive ions enter the neuron, making it more susceptible to fire an action potential. On the other hand, hyperpolarization makes less susceptible to fire when negative ions enter the neuron. Each neuron receives depolarizing and hyperpolarizing currents from many neurons. The neuron fires an action potential when the depolarizing currents (positive ions) minus the hyperpolarizing current (negative ions) exceed minimum intensity (threshold) (Vervaeke et al. 2010).

Comprehensive nerve linkage network connection is required to describe how nerve cells communicate. The junction between the axon tips of the sending neuron and the dendrite or soma of the receiving neuron is called “synapses”. The transferred communication between the tiny gap (Sahores and Naranjo 2008, Galarreta and Hestrin, 2001) is called the synapses “gap” or “cleft”. At those gaps, nerve cells approach within a distance of 3.5 nm between each other. The typical and most frequent type of synapses is the one in which the axon of one neuron connects to a second neuron by usually making contact at one of its dendrites or the cell body. The general information flow direction is from the axon terminal to the target neuron; therefore, the axon terminal is called “presynaptic” (carries information towards a synapses) and the target neuron is called “postsynaptic” (carries information from a synapses). Most mammalian synapses are chemical; however, there is an uncomplicated electrical synapses form that allows the directly transferred ionic current through one cell to the next. In the chemical synapses type, the incoming signal is transmitted when one neuron releases a neurotransmitter into the synaptic cleft which is detected by the second neuron activate receptors opposite to the release site (Jacquir et al. 2006, Mancilla et al. 2007). The synaptic delay for a chemical synapse is typically about 2 ms, while the synaptic delay for an electrical synapse may be about 0.2 ms. The electrical synapses take place in gap junctions as shown in Figure 2, in which the connexon channel in connexin (Postma et al. 2011) allows ions to pass directly from the cytoplasm of one cell to another one. The electrical synapses transmission is very rapid, thus, an action potential in the presynaptic neuron can be produced almost instantaneously. The ventrobasal nucleus (VBN), the primary somatosensory area of the thalamus was explained in (Pozza et al. 2010). The electrical synapses were common between VBN neurons during the first postnatal week, and decrease during the second week as chemical synaptic circuits emerge. Parker et al. (2009) calculated two isopotential neurons coupled directly by a single junction using values of the injected currents and voltage response of each cell junction conductance. Furthermore, conductance-base neural model calculate the synchronizing action of electrical synapses between connexin (Mancilla et al. 2007). There are several types of connexin in neurons such as Cx32, Cx36, Cx43, Cx45, and Cx47, where most of the electrical coupling between VBN cells requires Cx36. The junction potential coupling from optical spin technique is analyzed and demonstrated by our proposed network.

Figure 2. The electrical synchronized model by the electrical neurotransmitter.

Theoretical background

The optical dipole interaction model in many substances illustrates the origin of various optical effects. At nano-scale, photon from source generator causes optical effect of light interaction in nano-structure. Polarization is a function of the nano-antenna cross section absorption with the electromagnetic-induced dipole in atom and gradient intensity. One of the interesting schemes is that the optical dipole is formed by spin manipulations in a PANDA ring resonator (Mitatha et al. 2011b), as shown in Figure 3, where a PANDA ring resonator is used for conversion dark–bright soliton pair. The orthogonal set of dark–bright soliton pair is decomposed into right and left circularly polarized wave, where finally many spins can be generated and achieved. Theoretical review for this concept is presented as following:

Figure 3. A schematic diagram of a PANDA ring resonator.

The relative phase of the two output light signals after coupling into the optical coupler is π/2. The signals coupled into the drop port and the through port obtained a phase of π with respect to the input port signal. The input and control fields at the input port and control port are produced by the dark and bright optical solitons described as follows.

where A₀ is the optical field amplitude and z is propagation distance. is the dispersion length of the soliton pulse. T = t − β₁z, where β₁ and β₂ are the coefficients of the linear and second-order terms of Taylor expansion propagation constant. T₀ is a soliton pulse width at initial input, where the soliton phase shift time is t, and the frequency shift of the soliton is ω₀. The optical fields of the system in PANDA ring resonator given as follow.

Here E_i is the input field, E_t is the through field, E_d is the drop field, E_a is the control field, E₁, E₂, E₃, and E₄ are the fields in the Ring, κ₁ is the field coupling coefficient between the input bus and ring, κ₂ is the field coupling coefficient between the ring and output bus, T is the time taken for one round trip (roundtrip time), L is the circumference of the ring, and α is the power loss in the ring per unit length. We assume the lossless coupling is and . The output power or intensities at the through port and drop port are written as

where (the half-round-trip amplitude), , (the half-round-trip phase contribution), and .

Simulation results

The Spinnet system using the PANDA ring resonators to generate the orthogonal soliton sets is shown in Figure 4. In this system simulation (Figure 3), the coupling coefficient ratios κ₁:κ₂ are 50:50, 90:10, and 10:90 and R_r = R_l = 5 μm by using a microring, R_Th = R_add = 15 μm and the ring radii R_ad = 25 μm, A_eff = 0.25 μm², n_eff = 3.14 (for InGaAsP/InP) (Glomglome et al. 2012), α = 0.1 dB/mm, γ = 0.01, and λ₀ = 1.55 μm. The optical fields are generated by a dark–bright soliton pump based-on through port and drop port of microring resonator at wavelength 1.55 μm. Many optical spins are detected at the through and add ports of a PANDA ring resonator. The soliton optical field is fed into the ring resonator system. The initial spin states form the magnetic field. The magnetic field is induced by a gold nano-antenna coupled on AlGaAs waveguides for optical spin-up and spin-down states.

Figure 4. A schematic of nerve communication system.

The high optical power source initiates the highest SPR, which is vital to generate optical intensity and polarization. The Spinnet nerve communication system design known as “Spinnet” is shown in Figure 4. All parameters were chosen closely to the practical parameter in which the proposed device can be fabricated and realized (Seok et al. 2011, Armelles et al. 2008, Fischer and Martin et al. 2008, Thammawongsa et al. 2012). Figure 4(a) is illustrated in previous section which added the multiplexer and demultiplexer for transmissions and detection of different wavelength in the network. In Figure 4(b), R_Th and R_add represents as the add-drop filter ports to transmit and detect pulse signal. The coupling area is shown in Figure 4(c). Figure 5 shows the cell coupling between dendrite 1, dendrite 2 and nano-antenna. The optical nano-antenna is placed outside the neural cell near the gap junction at a distance of about 20 nm for optimum radiation and detection. The adjacent normal nerve cells are able to receive the external radiations from nano-antenna placed outside the neuron cell near the gap junction and adjacent normal cells can receive the signal. The coupling is established at specific frequencies to targeted cells.

Figure 5. Cell coupling with nano-antenna model.

As a result, the output signals are received at the through and drop ports as illustrated in Figure 6. Many potential wells can be generated by a PANDA ring and introduced by the nonlinear side ring effects by using the finite-difference time-domain (FDTD) method. The spontaneous activity is occurred due to the interaction of the electrical fields between the gap junction and nano-antenna, which is induced by the wave–particle duality and energy discrepancy. In which the SPR of device can be converted to the optical radiation via the nano-antenna, where more details are found in reference (Thammawongsa et al. 2012). The random transverse electric (TE) and transverse magnetic fields of the solitons correspond to the left-hand and right-hand photons which can be generated and detected. Furthermore, an angular momentum of either +ħ or ‐ħ is imparted to the object when a photon is absorbed by an object. There will be two possible spin states known as optical spins (Glomglome et al. 2012). The extensions of electrical coupling have been observed experimentally (Thammawongsa et al. 2012, van der Horst et al. 2008) for impulse potential generation. As an approximation, the coupling strength, the hyperpolarizing current pulses (600 ms) are fed into first cell (V₁) and coupled to neighbor cells (V₂). A coupling coefficient is calculated as V₂/V₁. The optical dipole pairs were considered to be electrically coupled which was the minimum level that could be reliably detected under the conditions of experiments in (Parker et al. 2009). Also, the junction conductance is estimated using the values of the injected voltage and currents. The spontaneous firing of electrically coupled and spike transmission through electrical synapses is shown in Figure 7. The bursting driven by simultaneous current injects into both cells of coupled pairs in scale bars as 20 mV and 50 ms, where each membrane excitation patch has two important potential levels, the resting potential, which is the membrane potential value lying around ‐70 mV and is preserved as long as nothing perturbs the cell and the second potential called the threshold potential which has a higher value around ‐55 mV (Pangratz-Fuehrer and Hestrin 2011). The electrical synaptic inputs cause the membrane to depolarize or hyperpolarize which is the signal potential formed by optical spin dark–bright soliton can cause the membrane potential to rise up or fall down.

Figure 6. Optical spin-up and spin-down states in difference wavelength.

Figure 7. (a) Spontaneous firing of electrically coupled and (b) Spike transmission through electrical synapses.

The interaction of the electrical fields between the gap junction and nano-antenna can be described by using the atomic Bohr Theory as following details. When the radio frequency emits signal (energy) through neurons, the orbital electrons can be excited and moved to the excited state, in which the direct or indirect ionizations can be generated and energy exchanged. The energy exchange between electrons and neurons is occurred, where finally, the system is needed to adjust itself to be in the equilibrium state. Consequently, the energy exchange is released and the spontaneous emission occurred, which can be modeled by using the resistor–capacitor model to describe the gap junction's behavior as shown in Figures 8 and 9. In Figure 7(b), by using the low pass filter for synaptic equivalent circuit as shown in Figure 8, the presynaptic gap is connected by the postsynaptic conductor (C), which is parallel connected in the circuit. Result of resting potentials is shown in Figure 9, in which the system model is formed by the synaptic interconnection. The advantage of the proposed system is a simple system that can be fabricated to a nano-device for nerve communication system (Srithanachai et al. 2012).

Figure 8. Gap junction of the postsynaptic capacitance behaves as low pass filters.

Figure 9. The steady-state responsive pattern of excitatory neuron for three different levels of the resting potentials. Red: 0.5; Black: 0.1; blue: 0.05.

Discussion and conclusion

We proposed that the nano-antenna radiation can generate the spontaneous firing of electrically coupled and spike transmission through the electrical synapses as shown in Figure 5, where the coupling range is more than 20 nm. Therefore, the delay for presynapse to postsynapse is more than 50 ms. According to, the nano-antenna can be reach the target cells without any harm for cell and the nerve signals in optical network can overcome the dead region. The use of bio-antenna is another interesting device for cells communication link for gap adjustment, which will be our future work.

A nanoscale communication network using ring resonators has been proposed for nerve cell communications. The optical dipole is generated and detected by using the metal-coated waveguide. It is coupled to the nearby nerves or cells and can be formed by the near field effects. The coupling between optical dipole and nerve signals is formed and propagated with in the optical networks at specific wavelength for targeted cells. Simulation results have shown that the optical dipoles in the optical networks can be formed and used, in which dark and bright soliton pair can propagate for long distance in the network without electromagnetic interference. Optical spins and dipoles are established by the coupling effects between soliton pair and metallic waveguide, in which the TE and TM fields can be generated and detected. The coupling signals between cells are generated and demonstrated by the spontaneous firing of electrically coupled and spike transmission through electrical synapses, where the normalized amplitude of about 20 mV is observed. The nerve signals in optical network can overcome the dead region, and can be reach the target cells without any interference with the adjacent cells. In applications, this network can be used in medical diagnosis and therapeutic application such as disability and rehabilitation.

Acknowledgments

We would like to thank the Institute of Advanced Photonics Science, Nanotechnology Research Alliance, Universiti Teknologi Malaysia (UTM) and King Mongkut's Institute of Technology (KMITL), Thailand for providing the research facilities. This research work has been supported by UTM's Tier 1/Flagship Research Grant, MyBrain15 Fellowship/MOHE SLAI Fellowship and the Ministry of Higher Education (MOHE) research grant.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.