JPH0543377B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is designed to treat changes in brain function caused by fatigue, drowsiness, aging, circulatory system diseases, etc. using a head that is synchronized with heartbeats that reflect changes in cerebral blood flow. This invention relates to a simple non-invasive measuring device that detects and warns by measuring and processing impedance changes.

[Conventional technology] To measure changes in brain function, various intelligence tests such as the Wechsler Adult Intelligence Scale (WAIS) are used for normal people, and psychological measurement techniques such as the Hasegawa Dementia Screening Scale are used for elderly people. However, as a method of repeatedly measuring in daily life, it is difficult to accurately evaluate functional changes because it is influenced by familiarity and memorization of test items. On the other hand, brain cell necrosis, decreased cerebral blood flow, cerebrovascular stenosis, etc. associated with decline in brain function can be measured using measurement methods such as NMRCT and X-ray CT, but these methods require expensive and large-scale equipment. Therefore, there are restrictions on where it can be installed, and it is not portable. Additionally, it is invasive and cannot be considered a measurement method that can be used repeatedly in daily life. Therefore, there is a need for the development of a non-invasive measurement device that can be easily and safely used in daily life and is also portable.

[Problems to be Solved by the Invention] In order to solve the above-mentioned problems, the present invention aims to easily and safely measure changes in brain function repeatedly at home, at a health center, a small clinic, or while driving a car. - It relates to a small and simple device with portability that can give a warning by recording brain function levels and comparing them with standard values. As society continues to age, this device can be used to detect early signs of decline in brain function in the elderly, prevent blurred vision, and prevent drowsiness while driving.

[Means for Solving the Problems] In order to achieve the above object, the simple brain function change measuring device of the present invention measures temporal or secular changes in cerebral blood flow that are closely related to changes in brain function. We aim to evaluate short-term or long-term changes in brain function through simple lateral assessment. In other words, when brain function declines and the level of brain activity decreases, metabolism in the brain decreases, and oxygen consumption also decreases. Since cerebral blood flow changes in proportion to this, measurement of cerebral blood flow is an important indicator of changes in brain function.

This device consists of a measurement electrode that derives from the scalp the changes in brain impedance that occur in response to changes in blood vessel diameter in the brain, and a current that applies a constant current to the scalp by connecting it to a constant current application device and detecting the impedance changes. The measurement electrode is equipped with an application electrode, a synchronous signal measurement electrode that is attached to the rear of the left and right auricles and derives electrical changes that occur in synchronization with heart beats, and an electrode fixing device that effectively fixes these electrodes to the scalp. An impedance measurement device that measures in-vivo impedance changes as potential difference changes is connected to the impedance measurement device, and the impedance waveform is added and averaged using the signal corresponding to the heartbeat derived from the synchronous signal measurement electrode as a trigger. Connect the average circuit and further to this circuit,
It is constructed by connecting a device that applies various processing to the average impedance waveform, compares and judges it with standard values related to age and task status, and a device that issues an alarm.

[Operation] To use the simple brain function change measuring device configured as described above, the measurement electrode and current application electrode are attached to the scalp or forehead skin, and the synchronous signal measurement electrode is attached to the skin behind the left and right auricles. Using a constant current application device, a weak and harmless current that cannot be felt by the living body is applied to the head through the current application electrode, and at the same time, an impedance change corresponding to the change in blood flow in the brain that occurs in synchronization with the heartbeat is measured through the measurement electrode. Measure.
Since blood has a lower impedance than the scalp, skull, nerve cells, etc., an increase in cerebral blood flow results in a decrease in head impedance. Waveform shaping is performed by adding and averaging this impedance change waveform with a signal synchronized with the heartbeat derived by the synchronization signal measurement electrode, and the maximum amplitude value, maximum slope value, integral value, etc. are calculated for the average impedance waveform after shaping. is calculated by adding weighting based on heart rate, and compared with pre-input standard values corresponding to the average age and task, and alerts are given by visual or auditory stimulation for abnormal values, etc. .

As mentioned above, this device notifies changes in brain function or brain activity level using cerebral blood flow as an indicator, but it not only measures functional decline due to abnormalities in the cerebral circulatory system or brain cells, but also measures fatigue, drowsiness, etc. A wide range of applications can be considered, such as measuring normal but temporary changes in brain function.

[Example] FIG. 1 shows an example of a simple brain function change measuring device according to the present invention.

This brain function change measuring device consists of a pair of impedance measuring electrodes 1a and 1b that detect changes in the impedance of a living body on the cleansed skin of the head or forehead.
a pair of current applying electrodes 2a, 2b for applying a current serving as a medium for measuring impedance changes to both outer sides, and a synchronous signal measuring electrode 3a for deriving electrical changes corresponding to heart beats.
3b. The arrangement of the measurement electrodes and current load electrodes and the mutual distance between the electrodes vary depending on the type of brain function to be measured. In general, experimental results have shown that the greater the distance between the current-applying electrodes, the more likely it is to reflect functional changes in deeper regions within the brain.
Therefore, when the main objective is to measure functional decline deep in the brain, it is desirable to increase the distance between the current applying electrodes.

The current applying electrodes 2a, 2b are connected to a constant current applying device 4 that outputs a constant current, and the measuring electrodes are connected to an impedance change measuring device 5. The constant current applying device 4 includes current applying electrodes 2a and 2b.
A constant current of less than 500 microamperes, which is harmless to the living body, is passed at several tens of kHz through the electrodes 1a and 1a. 1b and detected by the impedance change measuring device 5. FIG. 2 shows output waveforms derived from the occiput of the impedance change measuring device when the subject is at rest with his eyes closed and when a visual stimulus is loaded (observing a television program). Each waveform corresponds to changes in cerebral blood flow synchronized with heart beats, and the peak of the waveform indicates the point at which the maximum blood flow occurs. When we are at rest with our eyes closed, the brain's information processing activity level is low, so the amount of blood flowing into the brain is small, and the amplitude of the impedance change waveform is small. However, when we are looking at interesting visual stimuli, the brain's activity level increases. It has been shown that the cerebral blood flow also increases, and therefore the amplitude of the impedance change also increases. In order to shape this impedance change waveform, electrical changes accompanying the heartbeat are derived through the synchronous signal measuring electrodes 3a and 3b placed behind the left and right auricles, amplified and shaped by the synchronous signal measuring device 6, and then added. In the averaging circuit 7, the output of the impedance measuring device 5 is averaged multiple times using the output of the synchronizing signal measuring device 5 as a trigger, and for this averaged waveform, the maximum amplitude value and the maximum slope are determined in the impedance change waveform processing/judgment device 8. Values, etc. are weighted and calculated based on heart rate, and a visual or auditory alarm device 9 warns of deviations from the standard value based on the average or personal standard value for each age group. can.

[Effects of the Invention] According to the simple brain function decline measuring device of the present invention detailed above, it is possible to detect not only a long-term decline in brain function level due to brain disease or aging, but also a short-term decline due to falling asleep, fatigue, etc. It is possible to non-invasively measure and issue an alarm regarding a decline in brain activity level using a simple device, and it can be used in various real-life situations such as hospitals, homes, and driving a car.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a simple brain function decline measuring device according to the present invention, and FIG. 2 shows experimental results regarding the relationship between brain activity level and impedance change waveform. It is easily recognized that the amplitude value of the waveform increases when observing a TV program compared to when the subject is resting and eyes closed. 1a, 1b... Impedance measurement electrode, 2
a, 2b... current applying electrode, 3a, 3b... synchronous signal measuring electrode, 4... constant current applying device, 5... impedance change measuring device, 6... synchronous signal measuring device, 7... averaging circuit, 8... Impedance change waveform processing/judgment device, 9... Alarm device.

Claims (1)

[Claims] 1 A pair of impedance measurement electrodes are placed on the scalp or forehead skin to detect head impedance changes corresponding to blood flow in the brain, and a weak constant current of several tens of kHz is connected to a constant current application device on both sides of the electrodes. A pair of current applying electrodes that load current into the brain and a pair of synchronous signal measuring electrodes that derive electrical changes in synchronization with the heartbeat are arranged, and the impedance measuring electrode changes in synchronization with the heartbeat. An impedance measuring device that measures only the change as a potential difference is connected, and its output is connected to an averaging circuit.On the other hand, a synchronizing signal measuring electrode is connected to the synchronizing signal measuring device, and the output is used as a trigger signal to run the averaging circuit. The waveform is shaped by adding and averaging the impedance change waveform, and the maximum amplitude value, integral value, maximum gradient value, etc. are calculated for the shaped waveform, weighting is performed by heart rate, and the standard value is calculated. 1. A simple brain function change measuring device characterized by having a processing/determination device for comparing the brain function level with a visual or auditory warning device that warns about the level of brain function based on the determination result.