Jounzal of Neuroscience Methods, 8 (1983) 9%102 99

Elsevier Biomedical Press

A VERSATILE AND INEXPENSIVE PLANIMETER SYSTEM

Peter C.BrunJes

Department of Psychology, Gilmer Hall, University of Virgin~, Charlottesville, VA 22901 (U.S.A.)

Key words: planimetry - microcomputer systems - quantitative neuroanatomy - cytomorphometrics - neuroanatomical measurement techniques - volumetric analyses

The Apple Computer graphics tablet system is a useful tool in

quantitative neuroanatomical studies. Thls paper describes a brief

program modification which converts the system into an efficient

planimeter and illustrates the potential for tailoring the device to meet

specific needs.

The recent trend towards quantitative neuroanatomical studies has

necessitated the development of rapid and reliable techniques for

quantiDJing the size, shape, and number of various morphological features.

In this note, we describe a simple modification of the Apple ][ Plus

microcomputer system which results in a ~ighly versatile and inexpensive

planlmeter. The Graphics Tablet system marketed by Apple (Apple Catalog

#A2MO029) includes routines for (I) calculating areas and distances, (2)

specifying system resolution, and (3) calibrating output in any desired

unit. Default settings (Delta = 2) yield point-to-point acuity of

slightly greater than ] ,-,. At this setting, the maximum contour accepted

is approximately 150 cm, well over what is usually necessary. The actual

working area of the tablet is 21.5 x 28.0 cm, allowing standard

photomicrographs to easily fit on the surface. We have used the system to

measure areas f r o m both microproJeotor images and directly from a

microscope using a camera lucida (BrunJes, 1983). The tablet system is

substantially faster than hand planimeters and much more accurate due to

fewer user-related errors. The system is also much more versatile than

"electror~c planlmeters": when not being used as a measuring device, it

0165-0270/'83/$03.00 ~ 1983 Elsevier Science Publishers B.V.

]00

can analyze data, act as a word processor or fulfill many other functions.

While it is obvious that the system is very useful as sold by the

manufacturer, it is easily tailored to meet the specifications of

particular applications. Apple supplies the user with complete

documentation and instructions for making program adjustments. An example

currently used in our laboratory is described below.

The program modification sets up 2 separate data registers each of

which allow for 3 independent area measurements. The program will

calculate: (I) the mean of the 3 measurements in each data register, (2)

the difference between the means of the 2 data registers. This function

is necessary when a smaller structure is embedded in a larger structure of

interest, and (3) the sum of the means of 2 data registers. This function

is necessary for combining portions of objects, which, due to plane of

section, appear disconnected in the image.

The user controls the computer by pressing the tablet's pen into small

boxes (buttons) at the top of the tablet work area. Apple supplies 22

undefined buttons, to which the program modification listed below ascribes

the following functions (from left to right).

Button Function

Buttons I-8 set up the first data register:

I. Data bin I

2. Clear bin I

3. Data bin 2

4. Clear bin 2

5. Data bin 3

6. Clear bin 3

7. Clear Register I

Last area calculated is stored

Sets bin I = 0

Last area calculated is stored

Sets bin 2 = 0

Last area calculated is stored

Sets bin 3 = 0

Sets bins I, 2, and 3 to 0

101

8. Mean Register I Calculates and displays average of

measurements stored in bins I-3,

prints data stored in bins I-3.

Buttons 9-16 set up register 2 in an identical way:

9. Data bin 4 Last area calculated is stored

10. Clear bin 4 Sets bins 4 = 0

11. Data bin 5 Last area calculated is stored

12. Clear bin 5 Sets bin 5 = 0

13. Data bin 6 Last area calculated is stored

14. Clear bin 6 Sets bin 6 = 0

15. Clear Register 2 Sets bins 4, 5, and 6 to O.

16. Mean Register 2 Calculates and displays average of

measurements stored in bins 4-6,

prints data stored in bins 4-6.

17. Difference between Calculates and displays absolute value of

Registers the dlfference between the means of

reg/sters I and 2, displays all

measurements.

18. Sum of Registers Calculates and displays sum of the means of

register I and 2, and displays all

measurements.

19-22. Puts computer into the "area" routine.

The program modification is listed below. To make the changes, one should

have the Graphics Tablet Software diskette in drive I and type the

followlnE commands, exactly as written:

UNLOCK TABLET CODE APPLESOFT LOAD TABLET-CODE APPLESOFT DEL 2330,2580 290 IF X<O OR X>21 THEN GOSUB 1130: GOTO 170 295 ON X+1GOTO 2335,2340,2345,2350,2355,2360,2365,2370,2380,2385,

2390,2395,2400,2~05,2410,2415,2~30,2q40,1970,1970,1970,1970 2330 GOSUB 1130: GOTO 170

102

2335 AI : AR: GOTO 194 2340 AI = O: GOTO 194 2345 A2 = AR: GOTO 194 2350 A2 = O: GOTO 194 2355 A3 = AR: GOTO 194 2360 A3 = O: GOTO 194 2365 AI = O:A2 = O:A3 = 0: GOTO 194 2370 M1 = (At + A2 + A3) / 3: GOSUB 2455: VTAB 6: PRINT "MEAN

EQUALS ";MI: GOSUB 2445: GOSUB 1300: GOSUB 1300: GOTO 300 2380 A4 = AR: GOT0 194 2385 A4 = O: GOTO 194 2390 A5 = AR: GOTO 194 2395 A5 = O: GOTO 194 2400 A6 = AR: GOTO 194 2405 A6 = O: GOTO 194 2410 A4 = O:A5 = 0:A6 = O: GOTO 194 2415 M2 = (A4 + A5 + A6) / 3: GOSUB 2455: VTAB 6: PRINT "MEAN

EQUALS ";M2: GOSUB 2450: GOTO 300 2430 A9 : ((AI + A2 + A3) / 3) - ((A4 + A5 + A6) / 3): GOSUB 2455:

VTAB 6: PRINT "THE DIFFERENCE BETWEEN MEANS IS "; ABS (A9): GOSUB 2445: GOSUB 2450: GOTO 300

2440 A8 = ((AI + A2 + A3) / 3) + ((A4 + A5 + A6) / 3): GOSUB 2455: VTAB 6: PRINT "THE SUM OF THE MEANS IS ";A8: GOSUB 2445: GOSUB 2450: GOTO 300

2445 PRINT "FIRST GROUP MEASURES ARE ";At;" ";A2;" ";A3: RETURN

2450 PRINT "SECOND GROUP MEASURES ARE ";A4;" ";A5;" ";A6": GOSUB 1300: GOSUB 1300: RETURN

2455 PRINT D$;"PR#O": PRINT D$;"IN#O": TEXT : HOME : RETURN 2490 GOSUB 1130: GOTO 170 SAVE TABLET-CODE APPLESOFT

Variable atlas: The program modification creates the following new variables:

AI-A6; Areas stored in bins I-6 MI; Mean of bins I-3 M2; Mean of bins 4-6 AS; Sum of MI and M2 A9; Difference of MI and M2

Acknowledgements: Supported by a grant from the University of Virginia

Research Policy Council and by NIH (NS 17476).

References: BrunJes, P. C. (1983) Olfactory bulb development in Acomvs

cahirinus: Is neural maturation similar in precoeial and altriclal

murlds? Dev. Brain Res., in press.

(Rece ived F e b r u a r y 9 t h , 1983) (Accepted March 9 t h , 1983)