JP2018110783A - Sympathetic nerve activity analysis technique - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for analyzing peripheral sympathetic nerve activities accurately and easily by reducing interference of an electric signal which is to be obstruction when measuring the peripheral sympathetic nerve activities.SOLUTION: A method is provided for evaluating tibia sympathetic nerve activities or fat sympathetic nerve activities using electric signals emitted by a tibial nerve or a fat nerve in the frequency bands of 50 Hz or more and 250 Hz or less, or 50 Hz or more and 400 Hz or less. Also, the method is provided for evaluating kidney sympathetic nerve activities or spleen sympathetic nerve activities using electric signals emitted by a kidney nerve or a spleen nerve in the frequency bands of 50 Hz or more and 600 Hz or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an analysis technique that enables evaluation of peripheral sympathetic nerve activity of an animal.

Nerves that transmit electrical signals from the central to peripheral tissues are classified into motor nerves and autonomic nerves. Among these nerves, the sympathetic nerve, one of the autonomic nerves, has various organs such as regulation of blood pressure via the kidney, regulation of heat production via adipose tissue, regulation of blood glucose via the pancreas, liver or adrenal gland. And is involved in the regulation of tissue function.
Therefore, the evaluation of peripheral sympathetic nerve activity in animals is used for the development of new medicines and new materials that can improve the health and pathological conditions through sympathetic nerve regulation. In fact, in recent years, many relationships between peripheral sympathetic nerve activity and health conditions, sleep states, disease states, and the like have been clarified. Furthermore, it has been reported that pharmaceuticals and food polyphenols improve health, sleep, and disease states through the regulation of peripheral sympathetic nerve activity.

Currently, the most widely used method for simple evaluation of peripheral sympathetic nerve activity is to analyze the frequency of RR interval (interval from one QRS wave on the electrocardiogram) to the next QRS wave. This is a method performed by looking at the distribution of the power spectral density obtained by the above. That is, the power spectrum density in the low frequency band (LF) reflects sympathetic nerve activity and parasympathetic nerve activity, and the power spectrum density in the high frequency band (HF) reflects paraswitching nerve activity. Therefore, a value obtained by dividing the power spectral density of LF by the power spectral density of HF is used as an index of sympathetic nerve activity.
However, the sympathetic nerve activity calculated from the frequency analysis of the RR interval merely reflects changes in the autonomic nerve activity of the heart. Therefore, it is impossible to know peripheral sympathetic nerve activity that specifically affects the functions of other organs and tissues other than the heart from the frequency analysis of the RR interval.

  In order to evaluate peripheral sympathetic nerve activity, it is common to use a method such as microneurography in which a nerve is brought into contact with a microelectrode or a microneedle electrode is inserted into the nerve to evaluate sympathetic nerve activity (non-native). Patent Document 1). However, such a method for evaluating peripheral sympathetic nerve activity is technically difficult and not easy. Therefore, a simple, easy and highly accurate method is required for evaluating peripheral sympathetic nerve activity.

  In the peripheral sympathetic nerve activity evaluation method, the main factor that raises the difficulty of the evaluation is the strength of the electrical signal generated by the sympathetic nerve specific to the organ or tissue. The intensity of electrical signals generated by sympathetic nerves specific to organs and tissues is very small, unlike the intensity of electrical signals of electrocardiograms used for cardiac autonomic nerve measurements. Therefore, when measuring electrocardiograms, other tissues other than the evaluation tissues based on the electrical signals derived from the in vitro environment such as electrical devices that do not cause a major problem, breathing, body movement, heart pulsation, vasomotion, etc. An electrical signal derived from, an electrical signal generated by a nerve other than the sympathetic nerve, and the like interfere with the measurement of peripheral sympathetic nerve activity. Thus, in the past, efforts have been made to reduce electrical signals that hinder measurement of peripheral sympathetic nerve activity.

As shown in Non-Patent Documents 2 to 5, in the conventional method, in order to reduce an electrical signal that hinders measurement of peripheral sympathetic nerve activity, a low frequency band of 0 to 50 Hz, 1, Electrical signals inside and outside the living body in the high frequency band from 000 to 3,000 Hz or more are removed and evaluated as neural activity.
However, in the conventional methods shown in Non-Patent Documents 2 to 5, since the reduction of the electrical signal that hinders the measurement of peripheral sympathetic nerve activity is insufficient, the accuracy of the evaluation is lowered and the difficulty of the evaluation is increased. It was. Therefore, when measuring peripheral sympathetic nerve activity, it has been necessary to further reduce the interference of electrical signals inside and outside the living body that hinders evaluation.

Burke SL, et al., Curr. Hypertens. Rep., 2011, vol. 13 (3), p. 249-257 Hamza SM, et al., Hypertension, 2012, vol. 60 (3), p. 856-864 Miki K, et al., Exp. Physiol., 2002, vol. 87 (1), p. 33-39 Miki K, et al., J. Physiol., 2002, vol. 545 (Pt 1), p. 305-312 Petiot E, et al., J. Physiol., 2001, vol. 537 (Pt 3), p. 949-959

  In view of the above, an object of the present invention is to provide a method for accurately and easily analyzing peripheral sympathetic nerve activity by reducing interference of electrical signals that hinder the measurement of peripheral sympathetic nerve activity. .

The present inventors have intensively studied in view of the above problems. As a result, the frequency of the main power spectrum density distribution of the electrical signal emitted by the peripheral sympathetic nerve in the distribution of the power spectrum density obtained by performing frequency analysis of the electrical signal emitted by the nerve of the tibia, fat, kidney, and spleen The band was identified. And it discovered that peripheral sympathetic nerve activity could be evaluated accurately and easily by analyzing the electrical signal of the specific frequency band of each tissue nerve identified.
The present invention has been completed based on these findings.

The present invention relates to a method for evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 400 Hz generated by a tibial nerve.
The present invention also relates to a method for evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 250 Hz generated by the tibial nerve.
The present invention also relates to a method for evaluating fatty sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 400 Hz generated by a fatty nerve.
The present invention also relates to a method for evaluating fatty sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 250 Hz generated by a fatty nerve.
The present invention also relates to a method for evaluating renal sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 600 Hz generated by a renal nerve.
The present invention also relates to a method for evaluating splenic sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 600 Hz generated by a splenic nerve.

The present invention also relates to a system for evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 400 Hz as an index among electrical signals generated by the tibial nerve.
The present invention also relates to a system for evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 250 Hz as an index among electrical signals generated by the tibial nerve.
The present invention also relates to a system for evaluating fatty sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 400 Hz among electrical signals generated by fatty nerves.
The present invention also relates to a system for evaluating fatty sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 250 Hz among electrical signals generated by a fatty nerve.
The present invention also relates to a system for evaluating renal sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 600 Hz as an index among electrical signals generated by the kidney nerve.
Furthermore, the present invention relates to a system for evaluating splenic sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 600 Hz as an index among electrical signals generated by the splenic nerve.

  According to the present invention, the analysis efficiency and accuracy of the sympathetic nerve activity of each tissue can be improved by reducing the electrical signals originating from inside and outside the living body that do not originate from the sympathetic nerve.

The graph of FIG. 1 (A) shows the power spectrum of the tibial nerve activity before and after administration of the sympathetic nerve blocker and the power spectrum of noise derived from the environment when measuring the tibial nerve activity. The graph of FIG. 1 (B) shows the power spectrum of fatty nerve activity before and after administration of the sympathetic nerve blocker, and the power spectrum of noise derived from the environment when measuring fatty nerve activity. The graph of FIG. 1 (C) shows the power spectrum of renal nerve activity before and after administration of the sympathetic nerve blocker and the power spectrum of noise derived from the environment when measuring the renal nerve activity. The graph of FIG. 1 (D) shows the power spectrum of splenic nerve activity before and after the administration of the sympathetic nerve blocker and the power spectrum of noise derived from the environment when measuring the splenic nerve activity. The graph of FIG. 2 (A) shows the change in oscillogram of tibial nerve activity due to analysis frequency band limitation. The graph of FIG. 2 (B) shows the change in oscillogram of fatty nerve activity due to analysis frequency band limitation. The graph of FIG. 2C shows changes in the oscillogram of renal nerve activity due to analysis frequency band limitation. The graph of FIG. 2 (D) shows an oscillogram change of splenic nerve activity due to analysis frequency band limitation. As a representative example in which the visibility of peripheral sympathetic nerve activity is improved by the restriction of the analysis frequency band, a detailed change in oscillogram of tibial nerve activity is shown.

  The present invention acquires the nerve activity transmitted from the center to the peripheral tissue as an electrical signal, performs frequency analysis of the obtained electrical signal, and derives from various nerve activities in a specific frequency band of 50 Hz to 1,000 Hz. To analyze peripheral sympathetic nerve activity.

The nerve is composed of an afferent nerve that transmits information from the peripheral tissue to the center and an efferent nerve that transmits information from the center to the peripheral tissue. The afferent nerve is composed of somatic sensory nerves and visceral sensory nerves, and the efferent nerve is composed of motor nerves and autonomic nerves.
In peripheral tissues, these afferent nerves and efferent nerves form nerve bundles. In general, nerves visible using an optical microscope or the like are nerve bundles and include afferent nerves and efferent nerves. For example, the rat sciatic nerve is composed of about 14,000 nerve fibers including afferent and efferent nerves regardless of nerves less than 1 mm in diameter (Schmalbruch H., Anat. Rec., 1986, vol. 215 (1), p.71-81). Therefore, when accurately evaluating peripheral sympathetic nerve activity, it is necessary to separate nerves other than sympathetic nerves, that is, afferent nerves, motor nerves, and sympathetic nerves, from a bundle of nerves. However, since the nerve is thin, there is a possibility of damaging the nerve during separation.
On the other hand, according to the present invention, peripheral sympathetic nerve activity of each tissue can be evaluated without separating motor nerves from a bundle of nerve fibers. Therefore, the possibility of damaging nerves is reduced, and peripheral sympathetic nerve activity can be easily evaluated.

In the present invention, first, an electrical signal generated by the nerve activity of each tissue is measured. The method for measuring the electric signal can be appropriately selected from conventional methods. Examples include a multi-unit nerve fiber response recording method, a single unit nerve fiber response recording method, a patch clamp method, and a Ca ²⁺ imaging method. Since the present invention is a method of measuring peripheral sympathetic nerve activity from a nerve bundle, it is preferable to measure an electrical signal by a multi-unit nerve fiber response recording method that measures nerve activity using a nerve bundle. In addition, since nerve activity occurs in milliseconds, it is preferable that the acquisition speed of the electric signal is 1,000 samples / second or more in order to accurately acquire the electric signal. More preferably, it is performed in seconds or more.

According to the present invention, peripheral sympathetic nerve activity can be evaluated without separating motor nerves from a bundle of nerve fibers.
In a preferred embodiment of the present invention, when measuring electrical signals of the tibial nerve, fatty nerve, or splenic nerve, it is preferable that the peripheral side of the tissue to be evaluated for nerve activity is cut or destroyed. By cutting or destroying the peripheral side of the tibial nerve, fatty nerve, or splenic nerve, the involvement of afferent nerve activity in the electrical signal of the tibial nerve, fatty nerve, or splenic nerve can be removed.

In the present invention, when evaluating the sympathetic nerve activity of the tibia, in order to reduce the interference of the electrical signal derived from the environment and the interference of the electrical signal considered to be derived from a living body other than the sympathetic nerve, In particular, an electrical signal in a frequency band of 50 Hz or more and 400 Hz or less generated by the tibial nerve (derived from tibial sympathetic nerve activity) is analyzed. In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 400 Hz within a range not impairing the effects of the present invention. For example, the lower limit value is in the range of 50 to 70 Hz in consideration of the ratio of the electrical signal (N: noise) not derived from the neural activity to the electrical signal (S: signal) derived from the neural activity, that is, the S / N ratio. Is preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 230 to 400 Hz, and more preferably set within a range of 240 to 400 Hz.
Further, from the viewpoint of further improving analysis efficiency and accuracy, it is preferable to analyze a biological signal in a frequency band of 50 Hz to 250 Hz derived from tibial sympathetic nerve activity among measured electrical signals. In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 250 Hz within a range not impairing the effects of the present invention. For example, considering the S / N ratio, the lower limit value is preferably set within a range of 50 to 70 Hz, and more preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 230 to 250 Hz, and more preferably set within a range of 240 to 250 Hz.

In the present invention, when evaluating sympathetic nerve activity of fat, in order to reduce interference of electrical signals derived from the environment, fatty nerves are emitted even in the measured electrical signals (derived from fatty sympathetic nerve activity) from 50 Hz to 400 Hz. The biological signal in the frequency band of is analyzed. In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 400 Hz within a range not impairing the effects of the present invention. For example, considering the S / N ratio, the lower limit value is preferably set within a range of 50 to 70 Hz, and more preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 230 to 400 Hz, and more preferably set within a range of 240 to 400 Hz.
In addition, from the viewpoint of further improving analysis efficiency and accuracy, it is preferable to analyze a biological signal in a frequency band of 50 Hz to 250 Hz derived from fatty sympathetic nerve activity among measured electrical signals. In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 250 Hz within a range not impairing the effects of the present invention. For example, considering the S / N ratio, the lower limit value is preferably set within a range of 50 to 70 Hz, and more preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 230 to 250 Hz, and more preferably set within a range of 240 to 250 Hz.

In the present invention, when evaluating the sympathetic nerve activity of the kidney, in order to reduce the interference of the electrical signal derived from the environment, the renal nerve is emitted (derived from the renal sympathetic nerve activity) from 50 Hz to 600 Hz even in the measured electrical signal. The biological signal in the frequency band of is analyzed.
In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 600 Hz within a range not impairing the effects of the present invention. For example, considering the S / N ratio, the lower limit value is preferably set within a range of 50 to 70 Hz, and more preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 580 to 600 Hz, and more preferably set within a range of 590 to 600 Hz.

In the present invention, when evaluating the splenic sympathetic nerve activity, the splenic nerve is generated in the measured electric signal (derived from the splenic sympathetic nerve activity) from 50 Hz to 600 Hz in order to reduce the interference of the environment-derived electric signal. The biological signal in the frequency band of is analyzed.
In this case, the upper limit value and the lower limit value of the frequency band to be analyzed can be appropriately set within a range of 50 to 600 Hz within a range not impairing the effects of the present invention. For example, considering the S / N ratio, the lower limit value is preferably set within a range of 50 to 70 Hz, and more preferably set within a range of 50 to 60 Hz. From the same viewpoint, the upper limit value is preferably set within a range of 580 to 600 Hz, and more preferably set within a range of 590 to 600 Hz.

  In the present invention, it is preferable to remove an electrical signal that does not include sympathetic nerve activity from the measured electrical signal. Eliminating electrical signals that do not include sympathetic nerve activity eliminates environmental electrical noise generated from fluorescent lights, rotating bodies, personal computers, air conditioning systems, LEDs, etc., and improves analysis efficiency and accuracy of sympathetic nerve activity Further improvement can be achieved.

In the acquired neural activity, in order to analyze the amount of neural activity in an arbitrary analysis frequency band, it is preferable to apply a digital filter using frequency analysis.
For frequency analysis, fast Fourier transform, Fourier transform, wavelet transform, cosine transform, or the like may be employed. Here, “Fourier transform” includes discrete Fourier transform, short-time Fourier transform, and the like. The “cosine transform” includes a discrete cosine transform, which is a special discrete Fourier transform, and a modified discrete cosine transform, which is a method of the discrete cosine transform. “Wavelet transform” includes continuous wavelet transform, discrete wavelet transform, and the like. In the present invention, when data discontinuity becomes a problem during frequency analysis, in order to facilitate frequency analysis, “Kaiser window”, “Hamming window”, “Gauss window”, “rectangular window”, It is preferable to use window functions such as “Hanning window”, “Blackman window”, and “Bartlett window”.
As the digital filter, an FIR (finite impulse response) filter having a finite impulse response and an IIR (infinite impulse response) filter having an infinite impulse response can be used.
Using these analysis techniques, the power spectrum density at each frequency, the electric signal intensity in the specific frequency band specified by the nerve type, and the electric signal amount are calculated as the sympathetic nerve activity amount from the acquired neural activity.

As the configuration of the evaluation system for sympathetic nerve activity of the present invention, the configuration of a normal evaluation system for sympathetic nerve activity can be employed. For example, an electrode unit for acquiring an electrical signal emitted from a nerve, an amplification unit for amplifying the electrical signal, and an analysis unit for analyzing the electrical signal are included.
An electrode means a conductor used to provide electrical contact with nerves, and is usually stainless steel, copper, silver chloride coating, or stainless steel covered with Teflon (registered trademark) other than the contact part with nerves. Thin needles and electric wires made of tin, gold or silver. An electrode part refers to a site | part until this electrode is connected to an amplifier part. Other than the electrode part that is in direct contact with the nerve, the part where the electrode may come into contact with the fluid such as tissue fluid is completely made of silicon and mineral oil to prevent electrical noise from entering through the liquid from the outside. It is preferable to coat and insulate. There are various types of electrodes such as a clamp type, a fork type, and a needle type. In the present invention, the shape can be appropriately selected. However, there are cases where a DC voltage or a commercial AC voltage is mixed as an electrical noise derived from the outside in the acquired electrical signal of the peripheral sympathetic nerve. For this reason, it is preferable to extract a potential difference as a differential voltage from two or more electrodes of an electrical signal generated by a nerve. Therefore, it is preferable to use a bipolar electrode or an electrode that also has a ground electrode.
The amplifying unit refers to an electrical signal amplifier that amplifies an electrical signal generated by a minute nerve activity, which is generally several hundreds nV to several tens of μV, to several tens to several tens of thousands of times until connected to the analysis unit. Since the electric signal is taken out as a differential voltage, it is preferable to use a differential amplifier as the amplifier.
The analysis unit includes a reception unit for the signal generated from the amplification unit, an analysis device for analyzing the power spectral density by frequency analysis, an analysis device for extracting and integrating the differential voltage intensity in a specific frequency band from the electrical signal, Consists of a display for displaying the analysis results and a recording device for recording the results. The analysis device performs frequency analysis in the specific frequency band described above. Moreover, it is preferable that the analysis can be performed in real time simultaneously with the acquisition of the electric signal.

Peripheral nerves may be difficult to distinguish from lymphatic vessels, microarteries, microvenous veins, etc., depending on the tissue site. For this reason, when measuring peripheral sympathetic nerve activity, there are cases where lymphatic vessels, micro arteries, and micro veins are mistakenly measured as nerves. Even if the peripheral nerve can be accurately measured, there may be a case where other types of nerves other than the peripheral sympathetic nerve are mixed, or a microvessel is mixed in the nerve provided for the measurement. And they may become a source of electrical noise, and peripheral sympathetic nerve activity may not be measured. In order to avoid such a situation, it is necessary to confirm whether or not the electrical signal being measured is a peripheral sympathetic nerve based on the waveform of the oscillogram being measured or a decrease in the electrical signal due to the sympathetic blocker.
However, as shown in the left graph of FIG. 2A and the left graph of FIG. 3, it is not possible to determine whether the measurement target is peripheral sympathetic nerve activity from the oscillogram waveform of the conventional method. There is. In that case, it is necessary to change the measurement target, to finely divide the nerve of the measurement target, and to separate the measurement evaluation itself.
On the other hand, if the analysis of a specific frequency band is used as in the present invention, as shown in the graph on the right side of FIG. 2, the noise derived from the environment is reduced, and the biological origin derived from various nerves outside the sympathetic nerve As shown in the graph on the right side of FIG. 3, the visibility of the waveform of the oscillogram is greatly improved. Therefore, it is possible to suppress the occurrence of such a misidentification event.

Peripheral sympathetic nerves regulate skin and muscle blood flow through peripheral blood vessels, blood pressure through kidneys, heat production through adipose tissue, immune function regulation through spleen, pancreas, liver or adrenal glands. It is involved in the regulation of the functions of various organs and tissues such as the regulation of blood glucose. Therefore, measurement of peripheral sympathetic nerve activity in animals can be used to investigate the cause of the onset of various pathological conditions and to screen for agents that regulate tissue function.
The evaluation method and the evaluation system of the present invention reduce the noise at the time of nerve activity measurement, and can easily and accurately measure the peripheral sympathetic nerve activity. Therefore, by using the evaluation method and the evaluation system of the present invention, it becomes possible not only to easily identify peripheral sympathetic nerve activity, but also to prove the involvement of peripheral sympathetic nerve activity in the pathogenesis of various pathologies. Can be accurate. Furthermore, low blood pressure via the renal sympathetic nerve, cardiovascular diseases such as high blood pressure, obesity via the fatty sympathetic nerve, muscle fatigue via the tibial sympathetic nerve, immune status via the splenic sympathetic nerve, It becomes possible to perform screening for peripheral sympathetic nerve modulators that regulate sleep states with high accuracy.
The neural activity to be measured by the evaluation method and evaluation system of the present invention may be human neural activity or neural activity of animals other than humans. In the present invention, the neural activity of animals other than humans is preferred.

  The present invention further discloses the following sympathetic nerve activity evaluation method and sympathetic nerve activity evaluation system with respect to the embodiment described above.

<1> 50 Hz or more generated by the tibial nerve (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 400 Hz or less (preferably within the range of 230 to 400 Hz) The tibial sympathetic nerve activity is evaluated by using an electrical signal in a frequency band of any frequency below (more preferably, any frequency within a range of 240 to 400 Hz).
<2> 50 Hz or more generated by the tibial nerve (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 250 Hz or less (preferably within the range of 230 to 250 Hz) The tibial sympathetic nerve activity is evaluated using an electrical signal in a frequency band of any frequency below (more preferably, any frequency within a range of 240 to 250 Hz).
<3> 50 Hz or higher (preferably higher than or equal to any frequency within the range of 50 to 70 Hz, more preferably higher than or equal to any frequency within the range of 50 to 60 Hz) 400 Hz or lower (preferably within the range of 230 to 400 Hz) Of the sympathetic nerve activity using an electrical signal in a frequency band of any frequency below or below, more preferably below any frequency within the range of 240 to 400 Hz.
<4> 50 Hz or higher (preferably higher than or equal to any frequency within the range of 50 to 70 Hz, more preferably higher than or equal to any frequency within the range of 50 to 60 Hz) 250 Hz or lower (preferably within the range of 230 to 250 Hz) Of the sympathetic nerve activity using an electrical signal in a frequency band of any frequency below or below, more preferably below any frequency within the range of 240 to 250 Hz.
<5> 50 Hz or higher (preferably higher than or equal to any frequency within the range of 50 to 70 Hz, more preferably higher than or equal to any frequency within the range of 50 to 60 Hz) 600 Hz or less (preferably within the range of 580 to 600 Hz) Or less, more preferably, any frequency within a range of 590 to 600 Hz), and a method for evaluating renal sympathetic nerve activity.
<6> 50 Hz or higher (preferably higher than or equal to any frequency within the range of 50 to 70 Hz, more preferably higher than or equal to any frequency within the range of 50 to 60 Hz) 600 Hz or less (preferably within the range of 580 to 600 Hz) The spleen sympathetic nerve activity is evaluated using an electrical signal in a frequency band of a frequency band of any frequency of 590-600 Hz or less.

<7> Of electrical signals emitted by the tibial nerve, 50 Hz or more (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 400 Hz or less (preferably 230 A system that evaluates tibial sympathetic nerve activity using as an index an electrical signal in a frequency band of any frequency within a range of ˜400 Hz or less, more preferably, any frequency within a range of 240 to 400 Hz.
<8> Among electrical signals generated by the tibial nerve, 50 Hz or more (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 250 Hz or less (preferably 230 A system that evaluates tibial sympathetic nerve activity using as an index an electrical signal in a frequency band of any frequency within a range of ˜250 Hz or less, more preferably, any frequency within a range of 240 to 250 Hz.
<9> 50 Hz or more (preferably any frequency within a range of 50 to 70 Hz, more preferably any frequency within a range of 50 to 60 Hz) of 400 Hz or less (preferably 230) A system for evaluating fatty sympathetic nerve activity using as an index an electrical signal in a frequency band of any frequency within a range of ˜400 Hz or less, more preferably, any frequency within a range of 240 to 400 Hz.
<10> 50 Hz or more (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz), 250 Hz or less (preferably 230) A system for evaluating fatty sympathetic nerve activity using as an index an electrical signal in a frequency band of any frequency within a range of ˜250 Hz or less, more preferably, any frequency within a range of 240 to 250 Hz.
<11> Of electrical signals emitted by kidney nerves, 50 Hz or more (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 600 Hz or less (preferably 580 A system that evaluates renal sympathetic nerve activity using an electrical signal in a frequency band of not more than an arbitrary frequency within a range of ˜600 Hz, more preferably not more than an arbitrary frequency within a range of 590 to 600 Hz as an index.
<12> Among electrical signals generated by the splenic nerve, 50 Hz or more (preferably any frequency within the range of 50 to 70 Hz, more preferably any frequency within the range of 50 to 60 Hz) 600 Hz or less (preferably 580 A system for evaluating splenic sympathetic nerve activity using an electrical signal in a frequency band of not more than an arbitrary frequency within a range of ˜600 Hz, more preferably not more than an arbitrary frequency within a range of 590 to 600 Hz as an index.

<13> The method or system according to any one of <1> to <12>, wherein sympathetic nerve activity is evaluated without separating motor nerves from a bundle of nerve fibers.
<14> When measuring electrical signals of the tibial nerve, fatty nerve, or splenic nerve, the above-mentioned <1> to <4>, <6> to < The method or system according to any one of 10>, <12>, and <13>.
<15> The method or system according to any one of <1> to <14>, wherein interference of an electrical signal derived from a living body other than the sympathetic nerve is reduced.
<16> The method or system according to any one of <1> to <14>, wherein an electrical signal not including sympathetic nerve activity is removed from the measured electrical signal.
<17> The frequency analysis of the sympathetic nerve activity is performed according to any one of the above <1> to <16>, which is performed by fast Fourier transform, Fourier transform, wavelet transform, or cosine transform, preferably fast Fourier transform. Method or system.
<18> The method or system according to any one of <1> to <17>, wherein the nerve activity of an animal other than a human is to be evaluated.
<19> Said <7>-<18> comprised from the electrode part for acquiring the electrical signal which a nerve emits, the amplification part for amplifying an electrical signal, and the analysis part for analyzing an electrical signal The system according to any one of the above.

  Hereinafter, the present embodiment for measuring neural activity will be described. In addition, this embodiment demonstrated below does not unduly limit the content of this invention described in the claim. In addition, all the configurations described in the present embodiment are not necessarily essential configuration requirements of the present invention.

[Test Example 1] Analysis of electrical signals generated by the tibial nerve Rats (SHR, male, 11 weeks old) were fasted for 18 hours, then dissolved in physiological saline and adjusted to a concentration of 0.25 g / mL A polyethylene catheter (Becton Dickinson) filled with sodium heparin (Mochida Pharmaceutical Co., Ltd., 100 unit / mL) adjusted with physiological saline under anesthesia (Wako Pure Chemical Industries, Ltd., 1 g / kg body weight, intraperitoneal administration) Was inserted into the right femoral vein. Thereafter, the outer thigh site was incised to expose the tibial nerve, and the exposed nerve was cut on the distal side (toe side).
Next, the distal terminal of the cut tibial nerve is connected to a Teflon (registered trademark) -coated bipolar stainless steel wire electrode (As634, manufactured by Cooner Wire), and silicon (Sil-Gel 604, manufactured by Wacker). The electrical signal emitted by the tibial nerve was acquired. Hereinafter, an electrical signal generated by the tibial nerve is expressed as “tibial nerve activity”. The tibial nerve activity is amplified using a preamplifier (JC-101B, manufactured by Nihon Kohden) and a high-sensitivity amplifier (MEG-5100, manufactured by Nihon Kohden) with a built-in bandpass filter (low cut: 50 Hz, high cut: 1 kHz). And output to a multipurpose data acquisition system (PowerLab 4/30, manufactured by AD Instruments), and data was recorded at a sampling rate of 10,000 samples / second.

After stabilization of tibial nerve activity, hexamethonium bromide dissolved in physiological saline as a sympathetic nerve blocker and adjusted to a concentration of 3.4 mg / mL (13.5 mg / kg body weight, manufactured by Wako Pure Chemical Industries, Ltd.) Was administered intravenously from the femoral vein catheter and changes in tibial nerve activity were recorded.
After the recording, a saturated potassium chloride aqueous solution was intravenously administered from the femoral vein catheter, and the rats were euthanized. The analysis of the acquired data was performed using LabChart analysis software (ver 7.0, manufactured by AD Instruments). LabChart analysis software uses a Hamming window as a window function for 30-second electrical signal data obtained before and after sympathetic blockade administration and after 20 minutes of euthanasia, and performs power spectrum analysis by fast Fourier transform. went. And the frequency band of the main sympathetic nerve activity was specified from the obtained power spectrum. Next, a Kaiser window (parameter β for adjusting the sidelobe attenuation is 6) is applied to all the acquired electric signal data as a window function, and a bandpass filter is applied using an FIR filter. By integrating the signal intensity every 0.1 second, the electric signal amount in the specific frequency band was calculated.
For comparison of the calculated electric signal amount, an average value of the electric signal amount for 1 minute or more was used. At the time of analysis, an electrical signal obtained after 20 minutes after euthanasia was used as an electrical signal that does not depend on a biological reaction, that is, an electrical noise derived from the environment.

[Test Example 2] Analysis of electrical signals generated by fatty nerves Urethane adjusted to a concentration of 0.25 g / mL by dissolving rats (SHR, male, 11 weeks old) for 18 hours and then dissolving in physiological saline. A polyethylene catheter (Becton Dickinson) filled with sodium heparin (Mochida Pharmaceutical Co., Ltd., 100 unit / mL) adjusted with physiological saline under anesthesia (Wako Pure Chemical Industries, Ltd., 1 g / kg body weight, intraperitoneal administration) Was inserted into the right femoral vein. Thereafter, an incision was made in the vicinity of the back scapula to expose the brown fatty nerve, and the exposed nerve was cut on the peripheral side (brown fat side). Then, the same operation as in Test Example 1 was performed to acquire an electrical signal emitted by the brown fatty nerve, and a power spectrum analysis by fast Fourier transform and calculation of an electrical signal amount in a specific frequency band were performed. Hereinafter, the electrical signal generated by the brown fatty nerve is expressed as “fatty nerve activity”.

[Test Example 3] Analysis of electrical signal generated by renal nerve Rat (SHR, male, 11 weeks old) was fasted for 18 hours, then dissolved in physiological saline and adjusted to a concentration of 0.25 g / mL A polyethylene catheter (Becton Dickinson) filled with sodium heparin (Mochida Pharmaceutical Co., Ltd., 100 unit / mL) adjusted with physiological saline under anesthesia (Wako Pure Chemical Industries, Ltd., 1 g / kg body weight, intraperitoneal administration) Was inserted into the right femoral vein. Thereafter, the dorsal part was incised to expose the renal nerve. Next, the kidney nerve is placed on a Teflon (registered trademark) -coated bipolar stainless steel wire electrode (As634, manufactured by Cooner Wire) and insulated and fixed using silicon (Sil-Gel 604, manufactured by Wacker). As in Test Example 1, power spectrum analysis by fast Fourier transform and calculation of the amount of electric signal in a specific frequency band were performed. Hereinafter, an electrical signal generated by the renal nerve is referred to as “renal nerve activity”.

[Test Example 4] Analysis of electrical signals generated by splenic nerves Rats (SHR, male, 11 weeks old) were fasted for 18 hours, then dissolved in physiological saline and adjusted to a concentration of 0.25 g / mL Under anesthesia (Wako Pure Chemical Industries, Ltd., 1 g / kg body weight, intraperitoneal administration), a polyethylene catheter (Becton Dickinson) filled with sodium heparin (Mochida Pharmaceutical, 100 unit / mL) adjusted with physiological saline. Was inserted into the right femoral vein. Thereafter, the dorsal part was incised to expose the splenic nerve. Next, the spleen nerve was placed on a Teflon (registered trademark) -coated bipolar stainless steel wire electrode (As634, manufactured by Cooner Wire), the spleen nerve located on the spleen side from the electrode was pressed and destroyed, and silicon (Sil- Gel 604 (manufactured by Wacker) is used to insulate and acquire an electrical signal generated by the splenic nerve, and in the same manner as in Test Example 1, power spectrum analysis by fast Fourier transform and calculation of the amount of electrical signal in a specific frequency band are performed. It was. Hereinafter, the electrical signal generated by the splenic nerve is expressed as “splenic nerve activity”.

[Measurement Example 1] Measurement of power spectrum density before and after administration of sympathetic nerve blocker and specification of analysis frequency band The power spectrum of nerve activity of each tissue before and after administration of sympathetic nerve blocker is shown in FIG.
Sympathetic nerve activity is reduced by administration of a sympathetic nerve blocker. Therefore, the frequency band in which the power spectrum has changed before and after the administration of the sympathetic nerve blocker indicates that the frequency band reflects the electrical signal generated by the sympathetic nerve, that is, the sympathetic nerve activity.
According to FIGS. 1A and 1B, it is clear that the sympathetic nerve activity in the tibial nerve and the fatty nerve exists in the frequency band of 50 Hz to 400 Hz on the power spectrum. Further, according to FIGS. 1C and 1D, it is clear that the sympathetic nerve activity in the kidney nerve and spleen nerve exists in the frequency band of 50 Hz to 600 Hz on the power spectrum.
Further, according to FIGS. 1A and 1B, the maximum of the power spectral density derived from the sympathetic nerve in the tibial nerve and the fatty nerve is biased toward the low frequency side, and the peak shape has a long tail on the high frequency side. It is clear that the main sympathetic nerve activity exists in the frequency band from 50 Hz to 250 Hz.
Furthermore, as shown in FIG. 1A, in the tibial nerve activity, on the power spectrum, there is a component whose activity is not suppressed by the sympathetic nerve blocker in the vicinity of 500 Hz, that is, a component that seems to be derived from the motor nerve.

Based on the above results, in the tibial nerve and fatty nerve, the frequency band of 50 Hz to 1,000 Hz, which is the entire frequency band acquired in this test, is the analysis frequency band (1), and the frequency band of 50 Hz to 400 Hz is the analysis frequency band ( 2) The frequency band of 50 Hz to 250 Hz was set as the analysis frequency band (3) and used for the following analysis.
In the kidney and splenic nerve, the frequency band of 50 Hz to 1,000 Hz was set as the analysis frequency band (1), and the frequency band of 50 Hz to 600 Hz was set as the analysis frequency band (2), and used for the following analysis.

[Measurement Example 2] Analysis of resolution of peripheral sympathetic nerve activity in specific analysis frequency band Based on the results of Measurement Example 1, in each specific analysis frequency band, the electric signal amount “B” before administration of the sympathetic nerve blocker in each nerve (Before) ”, electric signal amount“ A (After) ”after administration of a sympathetic blocker, environment-derived electric noise amount“ EN (Environment Noise) obtained from electric signal amount obtained 20 minutes after euthanasia ” Was calculated.
Further, the sympathetic nerve activity “S (Signal)” was calculated as a difference between the electric signal amounts before and after administration of the sympathetic nerve blocker, that is, a value obtained by subtracting “A” from “B”. Furthermore, an electrical noise “BN (Body Noise)” derived from a living body that is obstructed when sympathetic nerve activity is measured is derived from the electrical signal “A” obtained after administration of the sympathetic nerve blocker and containing no sympathetic nerve activity. The value was calculated by subtracting the noise “EN”.

  Further, in order to compare the separation performance of sympathetic nerve activity and noise in each analysis frequency band, the ratio of the amount of sympathetic nerve activity “S” and the amount of electrical noise “EN” derived from the environment, that is, the S / EN ratio, and The ratio between the amount of sympathetic nerve activity “S” and the amount of electrical noise “BN” derived from the living body, that is, the S / BN ratio was calculated. If these ratios are high, it indicates that the sympathetic nerve activity is clearly separated as a signal compared to the target noise and is accurately and precisely captured.

In addition, the S / EN ratio and S / BN ratio obtained by measurement in the analysis frequency band (1), and the S / EN ratio obtained by measurement in the analysis frequency bands (2) and (3), S / Compared with the BN ratio, the S / EN ratio improvement rate ((S / EN ratio in analysis frequency band (2) or (3)) / (S / EN ratio in analysis frequency band (1)) × 100 ( %)), And S / BN ratio improvement rate ((S / BN ratio in analysis frequency band (2) or (3)) / (S / BN ratio in analysis frequency band (1)) × 100 (%) ) Was calculated.
The S / EN ratio improvement rate indicates the improvement rate of the sympathetic nerve activity measurement accuracy by reducing the interference of environmental noise. On the other hand, the S / BN ratio improvement rate indicates an improvement rate of sympathetic nerve activity measurement accuracy due to reduction of interference of noise derived from a living body.
The obtained results were expressed as an average value ± standard error (Table 1). A paired t-test was used for the test of the difference between the mean values.

As shown in Table 1, for the tibial nerve, when the analysis frequency band (2) of neural activity is used, the S / EN ratio and S / BN ratio are higher than those analyzed in the analysis frequency band (1). The mean value was statistically significant.
As for fatty nerves, when the analysis frequency band (2) of neural activity is used, the average value of the S / EN ratio is statistically significantly higher than that analyzed in the analysis frequency band (1). It was.
For the renal nerve and spleen nerve, when using the analysis frequency band (2) of neural activity, the mean value of the S / EN ratio is statistically significantly higher than that analyzed in the analysis frequency band (1). Indicated.

Further, as shown in Table 1, for the tibial nerve, when the analysis frequency band (3) of neural activity is used, the S / EN ratio and S / BN are higher than those analyzed in the analysis frequency band (1). The average value of the ratio is statistically significantly higher than that of the analysis frequency band (2), and the average value of the S / EN ratio and S / BN ratio improvement rate is statistically significantly higher than that of the analysis frequency band (2). Indicated.
As for fatty nerves, when the analysis frequency band (3) of neural activity is used, the average value of the S / EN ratio is statistically significantly higher than that analyzed in the analysis frequency band (1). The average value of the S / EN ratio improvement rate was statistically significantly higher than the analysis frequency band (2).

[Measurement Example 3] Typical Improvement Example of Peripheral Sympathetic Nerve Activity Analysis Accuracy in Nerve Activity Analysis Using Each Frequency Band For the electrical signal data of each tissue nerve activity acquired in Test Examples 1 to 4, the analysis frequency A representative example of an oscillogram of electric signal data as a result of applying a bandpass filter using a Kaiser window (β = 6) as a window function and using an FIR filter in any of bands (1) to (3) It was shown in 2.
According to FIGS. 2 (A) and 2 (B), the difference in change before and after the administration of the sympathetic nerve blocker in the tibial nerve and the fatty nerve is clear by using the bandpass filter using the analysis frequency band (3). It is clear that
Further, according to FIGS. 2 (C) and 2 (D), in the kidney nerve and spleen nerve, the difference in change before and after administration of the sympathetic blocker is determined using a bandpass filter using the analysis frequency band (2). It is clear that this is clear.

  FIG. 3 shows an enlarged view of the difference in oscillogram before administration of the sympathetic blocker due to the difference in the analysis frequency band shown in FIG. The sympathetic nerve activity is regarded as a waveform having a large amplitude in the oscillogram, but it is clear that the large waveform is clearer than the small waveform.

According to the above results, for the tibial nerve, if an electrical signal in the frequency band of 50 Hz to 400 Hz of the electrical signal emitted by the nerve is used, the sympathy is compared with the conventional analysis method in the frequency band of 50 to 1,000 Hz. It has been clarified that interference of biological noise such as motor nerves and environmental noise with respect to neural activity can be reduced, and sympathetic activity can be analyzed with high accuracy. In particular, it has become clear that the use of electrical signals in the frequency band of 50 Hz to 250 Hz makes it possible to analyze the sympathetic activity of the tibia with higher accuracy.
For fatty nerves, using electrical signals in the frequency band of 50 Hz to 400 Hz of the electrical signals emitted by the nerve, compared to the conventional analysis method in the frequency band of 50 to 1,000 Hz, it is derived from the environment for sympathetic nerve activity It was found that noise interference can be reduced and sympathetic activity can be analyzed with high accuracy. In particular, it has been clarified that fat sympathetic activity can be analyzed with higher accuracy by using electrical signals in a frequency band of 50 Hz to 250 Hz.
For kidney nerves, using electrical signals in the frequency band of 50 Hz to 600 Hz of the electrical signals emitted from the nerve, compared to the conventional analysis method in the frequency band of 50 to 1,000 Hz, it is derived from the environment for sympathetic nerve activity It became clear that the interference of noise can be reduced and sympathetic activity can be analyzed with high accuracy.
For splenic nerves, using electrical signals in the frequency band of 50 Hz to 600 Hz of the electrical signals emitted by the nerve, compared to the conventional analysis method in the frequency band of 50 to 1,000 Hz, it is derived from the environment for sympathetic nerve activity It became clear that the interference of noise can be reduced and sympathetic activity can be analyzed with high accuracy.

Claims (12)

  A method for evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz or more and 400 Hz or less generated by a tibial nerve.   A method of evaluating tibial sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz or more and 250 Hz or less generated by a tibial nerve.   A method for evaluating fatty sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 400 Hz emitted from a fatty nerve.   A method for evaluating fatty sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz to 250 Hz emitted from a fatty nerve.   A method for evaluating renal sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz or more and 600 Hz or less emitted by a renal nerve.   A method for evaluating splenic sympathetic nerve activity using an electrical signal in a frequency band of 50 Hz or more and 600 Hz or less generated by a spleen nerve.   A system for evaluating tibial sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 400 Hz among electrical signals generated by the tibial nerve.   A system for evaluating tibial sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 250 Hz among electrical signals generated by the tibial nerve.   A system for evaluating fatty sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 400 Hz among electrical signals emitted from a fatty nerve.   A system for evaluating fatty sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 250 Hz among electrical signals emitted from a fatty nerve.   A system for evaluating renal sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 600 Hz among electrical signals emitted from the kidney nerve.   A system for evaluating splenic sympathetic nerve activity using, as an index, an electrical signal in a frequency band of 50 Hz to 600 Hz among electrical signals generated by the splenic nerve.