JPH09234187A - Living body activity-measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device comprising plural light receiving elements disposed as an array in the same plane by performing operation of reading information of the light receiving elements in order at the same timing for setting space resolution and/or view field changeable. SOLUTION: An optical detector comprising plural light receiving elements 201 (11, 12, 13...) each integrated with a gate switch 202 is provided with a horizontal direction reading control device (H-device) 203 and a vertical direction reading control device (V-device) 204. The gate switch 202 on the first line is opened by the V-device 204, and simultaneously, the gate switches 202 are opened from the first line on in order by the H-device 203. Next, designation by the V-device 204 is changed to the gate switch 202 on the second line, and the gate switches 202 are similarly opened from the first line on by the H-device 203, so the light receiving elements 201 in each line are read in order. Since all the light receiving elements 201 are read similarly, activity of a living body is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for optically measuring the activity of a living body, and more particularly to a device for optically measuring the activity of the cranial nerve system using a membrane potential sensitive dye.

[0002]

2. Description of the Related Art Conventionally, in the case of optically observing the activity of the cranial nerve system using a membrane potential sensitive dye, a dedicated current / voltage (I / V) converter is provided for each light receiving element such as a photodiode. A simultaneous sample-and-hold type measurement system with connected amplifiers (that is, the same number of light receiving elements, I / V converters, and amplifiers) was used (eg Biol. Cybern., 6
7, 501-509, 1992). The advantage of this method is that high-speed sampling of 10 kHz or more is possible, and at the same time, it is possible to realize readout with no time delay between each light receiving element. However, this simultaneous sample and hold measurement system
If the number of light receiving elements exceeds several thousand, it will be difficult to realize due to problems such as cost, I / V converter / amplifier wiring, and volume. Therefore, for example, a system for measuring cranial nerve activity with 16,384 light receiving elements (Journal of the Physical Society of Japan, 47 (9), 707-712, 199)
2) In (Reference 1), the scanning method in which the charges accumulated in the light receiving element are sequentially read out is adopted to achieve the required I /
By reducing the number of V converters and amplifiers, we have realized a commercially viable system.

[0003]

By the way, the spatial resolution and visual field required for observing cranial nerve activity vary depending on the target sample and the purpose of observation. For example, in the auditory cortex of the cerebral cortex of the guinea pig, observations aimed at overlooking the activity of the entire area and extracting its characteristics require a spatial resolution of 100 to 220 μm and a visual field of 3 to 5 mm square ( Biol. Cybern., 67, 501-509, 1992)
(Reference 2). In this case, the number of light receiving elements required for optical measurement is 128 to 2,500. On the other hand, when observing the auditory cortex in detail with the spatial resolution of nerve cells (diameter 10 to 25 μm), which is a constituent of the brain, the required number of light receiving elements is 14,40.
It will be between 0 and 250,000. Therefore, it is desirable that the spatial resolution and visual field that can be realized by the measurement system of cranial nerve activity can flexibly correspond to the observation sample and the observation purpose. As one of the methods for responding to this request, a method of preparing a plurality of light detection portions (camera portions) having different numbers of light receiving elements and using them properly can be considered. However, this method is costly and not practical. At present, there is no practical measurement system of cranial nerve activity whose spatial resolution or visual field is variable according to the observation conditions.

The present invention has been made in view of the above problems, and an object thereof is to provide a practical biological activity measuring system in which the spatial resolution or the visual field is variable according to the observation conditions.

[0005]

FIG. 5 shows the overall configuration of the measuring device of the present invention. The basic operation of this configuration is described in Reference 2 above.
Fig. 1 and its explanation.

A feature of the measurement of the living body (cranial nerve) activity in the present invention is that the light receiving elements are grouped and read out in the photodetector of the measuring device, as shown in FIG. In the conventional scanning method, all the light receiving elements 101 are read out one by one, as shown in the order of numbers in FIG. On the other hand, the method of the present invention is a method in which two groups of four light receiving elements are formed in the horizontal and vertical directions as shown in FIG. Here, the number of light receiving elements forming the group is
Not limited to 4 (2 x 2), 9 (3 x 3), 16 (4 x 4)
Alternatively, it may be 6 (2 × 3) or the like.

The advantage of the method of the present invention is, firstly, that the apparent number of light receiving elements can be easily changed according to the measurement conditions while using the same photodetecting portion. Therefore, it is not necessary to prepare a plurality of light detection portions having different numbers of light receiving elements, and the measurement system can be provided at low cost. Secondly, by sequentially reading the grouped light receiving elements, the total number of times of reading can be reduced, so that the scanning time for one screen is shortened and the time resolution of the measurement system is improved. In other words, if N light-receiving elements are grouped together, the time resolution is 1 / N compared to the conventional scanning method.
Can be

Here, the ideal time resolution in the system for measuring cranial nerve activity is 100 s or less. this is,
This is because the nerve information uses the action potential generated by nerve cells (membrane potential change of about 100 mV, time width of several ms) as a medium. However, in the scanning system, the time resolution is determined by the number of light receiving elements. That is, the larger the number of light receiving elements, the longer it takes to read out, and the scanning time for one screen, that is, the time resolution becomes worse. On the other hand, the spatial resolution of the measurement system improves as the number of light receiving elements increases in the case of observation in the same field of view. Therefore, it can be said that there is a trade-off relationship between the temporal resolution and the spatial resolution in the scanning measurement system. Therefore, if the time resolution at the time of measurement is prioritized over the spatial resolution, and is set to 100 μs, for example, the number of light receiving elements in the light detecting portion is constant, and conversely, the number of light receiving elements to be grouped can be determined.

When the activity of a living body is measured by a measuring device having such a large number of pixels (the light receiving element can be expressed as a pixel when viewed from the monitor side), it is also a problem to secure real-time monitoring of the observation result. is there. As a method of solving this, FIG.
The observation results are displayed to the observation experimenter by using a pattern composed of a small number of pixels specified in advance (for example, 1/10 of the total number of pixels) as shown in (a), (b) and (c). The characteristics of can be grasped almost in real time.

By the above method, it is an object of the present invention,
It is possible to provide a practical cranial nerve activity measurement system in which the spatial resolution or the visual field is variable according to the observation conditions.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A method of grouping light receiving elements and sequentially reading the light receiving elements according to the present invention will be described in detail with reference to the drawings.

First, FIG. 2 shows each of the light receiving elements 20 on the substrate.
1 (11, 12, 13 ... In the figure) shows an outline of a photodetector in which a gate switch 202 is integrated. This photodetector has a horizontal readout controller 203 and a vertical readout controller 20.
By setting the operation procedure of 4 as follows, it is possible to group the light receiving elements and read them sequentially. In FIG. 2, 205 is a control signal line (horizontal direction), 206 is a control signal line (vertical direction), 207 is a signal output line, and 208 is a control clock signal.

For comparison, a conventional scanning method is shown in FIG. 3 (a). First, open the first row gate switch (eg, MOS-FET, I in the figure) using the vertical direction read control device (eg, vertical shift register), and at the same time, read the horizontal direction read control device (eg, horizontal shift register). The gate switches (i →
ii → iii…). Then, the light receiving elements (for example, photodiodes) in the first row are sequentially (11 → 12 in the figure).
→ 13…) Read out. Next, the designation of the vertical read control device is changed to the gate switch in the second row (II in the figure), and at the same time, the gate switch (i → ii → iii in the figure) is sequentially changed from the first row by the horizontal read control apparatus. Open. Then, the light receiving elements in the second row are sequentially (21 → 22 →
23…) Read out. By repeating this, all the light receiving elements can be sequentially read.

An example of the scanning system of the present invention is shown in FIG. 3 (b). First, using the vertical read controller, the gate switches in the first and second columns (in the figure
A) open, and at the same time 1 by the horizontal readout controller
Gate switches for two rows in sequence from the second row (a → b in the figure)
→ Open c…). Then, the light receiving elements are grouped into groups of four (11,12,21,22 → 12,14,23,24 →
15,16,25,26…) Read out. Next, the designation of the vertical read control device is changed to the gate switches in the third and fourth columns (B in the figure), and at the same time, the horizontal read control device sequentially starts from the first column and the gate switches for the two columns (see the figure). Open the inside a → b → c…). Then, four light-receiving elements are sequentially arranged (31, 32, 41, 42 → 33, 34, 43, 44 → 35, 3 in the figure).
6,45,46 ...) Read out. By repeating this, all the light receiving elements can be grouped into four groups and sequentially read out.

A method according to the present invention for displaying information read from a predesignated light receiving element substantially in real time will be described with reference to the drawings.

FIG. 4A shows a light receiving element on the photodetector 401.
Equally spaced horizontally and vertically from within 101 (for example, 1
It is an outline of a method of displaying information of the light receiving elements extracted and designated as one for every 0 light receiving elements on the observation result display screen 402 in substantially real time. This method enables the observation experimenter to understand the characteristics of the observation result in almost real time.

In FIG. 4B, a part (for example, 10 × 10 parts) is extracted and designated from the light-receiving elements on the photodetector, and the information of the light-receiving elements at that portion is displayed on the observation result display screen. It is an outline of a method of displaying in real time substantially.

In FIG. 4 (c), a part (for example, 5 × 5 parts) of a light receiving element on a photodetector is extracted and designated at a plurality of points (for example, 4 points), and the light receiving element of the part is extracted. It is an outline of a method of displaying information on an observation result display screen substantially in real time.

[0019]

According to the method of the present invention, it is possible to easily change the apparent number of light receiving elements according to the measurement conditions while using the same light detecting portion. Therefore, it is not necessary to prepare a plurality of light detecting portions having different numbers of light receiving elements, and the measurement system can be provided at low cost. Further, by sequentially reading the grouped light receiving elements, the total number of times of reading can be reduced, so that the scanning time for one screen can be shortened and the time resolution of the measurement system can be improved.
In other words, if N light-receiving elements are grouped together, the time resolution can be reduced to 1 / N as compared with the conventional scanning method.

[Brief description of drawings]

FIG. 1 (a) shows a measurement system of cranial nerve activity,
(B) is a schematic diagram showing a conventional scanning method in which all the light-receiving elements are read out one by one, and the light-receiving elements are grouped in the light detection portion of the measurement system according to the present invention, and the groups are read out in order. The schematic diagram which shows the example of a system.

FIG. 2 is a schematic diagram showing an outline of a photodetector in which a gate switch is integrated in each light receiving element on a substrate.

FIG. 3 (a) is a schematic diagram showing a conventional scanning method using a horizontal and vertical direction readout control device, (b).
FIG. 6 is a schematic diagram showing an embodiment of a system according to the present invention in which the light-receiving elements are grouped by controlling the horizontal and vertical direction read control devices and the groups are sequentially read.

FIG. 4 (a) is a schematic diagram showing an example of an implementation of a substantially real-time display system of observation results, which is composed of predesignated pixels according to the present invention, and FIG. A schematic diagram showing another embodiment of a substantially real-time display system of observation results, which is composed of pre-designated pixels, (c) is, according to the present invention, composed of pre-designated pixels, The schematic diagram which shows another Example of the substantially real-time display system of an observation result.

FIG. 5 is an overall configuration diagram of a measuring device of the present invention.

[Explanation of symbols]

101 ... Light receiving element, 201 ... Light receiving element, 202 ... Gate switch, 203 ... Horizontal direction read control device, 204 ... Vertical direction read control device, 205 ... Control signal line (horizontal direction), 206 ... Control signal line (vertical direction) , 207 ... Signal output line, 208 ... Control clock signal, 401 ... Photodetector, 40
2… Observation result display screen.

Claims (3)

[Claims] 1. The activity of a living body is optically observed, which comprises a photodetector having a plurality of light receiving elements arranged in an array on the same plane, and having means for specifying each of the light receiving elements. In the apparatus, a spatial activity and / or a visual field are made variable by sequentially performing an operation of reading out information of a plurality of the light receiving elements at the same timing, and the biological activity measuring apparatus. 2. The operation for designating a plurality of light receiving elements for reading out information at the same timing is sequentially performed by using two read control means for specifying each of the light receiving elements. Measuring device. 3. An optical activity of a living body having a plurality of light receiving elements arranged in an array on the same plane and having a photodetector having means for specifying each light receiving element is optically observed. In the apparatus, the biological activity measuring apparatus is characterized in that the information read from a predetermined number of the light receiving elements smaller than the total number of the light receiving elements included in the photodetector is displayed substantially in real time.