Control of cage lighting by locomotor activity through feedback circuits

Physiology& Behavior,Vol. 33, pp. 487-490. Copyright~ Pergamon Press Ltd., 1984. Printed in the U.S.A.

0031-9384/84 $3.00 + .00

BRIEF COMMUNICATION

Control of Cage Lighting by Locomotor Activity Through Feedback Circuits J. S. FERRARO, W. S T O N E A N D C. E. M c C O R M A C K University o f Health Sciences, The Chicago Medical School 3333 Green Bay Road, North Chicago, IL 60064 R e c e i v e d 24 F e b r u a r y 1984 FERRARO, J. S., W. STONE AND C. E. McCORMACK. Control of cage lighting by locomotor activity through .feedback circuits. PHYSIOL BEHAV 33(3) 487-490, 1984.--This paper describes an electronic device through which environmental lighting conditions are linked to locomotor activity thus allowing only the photosensitive portions of a nocturnal rodents phase-response-curve to be exposed to light. In the past, this type of lighting schedule has been difficult, if not impossible, to present with an exogenously controlled lighting system due to the phase shifting ability of the rodent's circadian system. The feedback lighting system is made from components which can be purchased at most electronics outlets for less than $100. Circadian rhythms

Phase-response-curves

Feedback lighting

T H E photosensitive portion of a nocturnal rodent's circadian rhythm of locomotor activity occurs during the animal's active running phase, and the degree to which light signals advance or delay the phase of the rhythm is depicted by its phase-response-curve. It is difficult to expose major photosensitive portions of the phase-response-curve to bright light for more than one circadian cycle. This is due to the fact that when the nocturnally active rodent is exposed to bright light during its active phase, it quickly shifts the phase of its locomotor activity, and thus the photosensitive portion of its phase-response-curve, to a totally different time thus escaping the light signal. In the past, to assure that the photosensitive portions of the cycle were exposed to light for several consecutive days, long photoperiods or even continuous light (LL) had to be employed. H o w e v e r in some situations, the deleterious effects of such lighting on the integrity of circadian rhythms precludes its usefulness in studies of circadian photosensitivity; for example, in bright L L the rhythm of locomotor activity loses its circadian frequency [I]. In other situations the temporal continuity of L L diminishes its usefulness; for example, it is impossible with L L or long photoperiods to limit light signals exclusively to certain photosensitive portions of the animal's phaseresponse-curve. However, a possible means of accomplishing this would be to couple the lighting schedule electronically to the rat's activity rhythm. This paper describes an electronic device which does this without causing the loss of the circadian frequency of the locomotor activity rhythm. INSTRUMENT DESIGN Figure 1 shows a diagram of a functional feedback unit, the components of which are listed in Table I. All of the

487

components necessary for one feedback unit can be purchased at most electronic outlets for less than $100.00. The system is designed to direct power to a 115 volt A.C. electrical outlet for a variable length of time whenever the running wheel rotation rate reaches a predetermined criterion. An incandescent light of up to 200 watts may be plugged into the outlet. The feedback system contains a 5 V circuit, the flow of which is regulated by a microswitch which allows the mechanical turn of a running wheel to be interpreted as an electrical impulse. The first pulse from the microswitch triggers a timer (IC-I) and causes one count to be stored in a counter (IC-5 and IC-6). The period of the timer (IC-1) is set by the " T i m e - O u t " control. Additional wheel revolutions are also stored in the counter. If the preset number of revolutions, set by " D i p a t c h " J1 and J2, occur before IC-1 times out, timer IC-2 is triggered, relay RL-1 is energized and power is applied to the 115 volt outlet. The relay is energized until IC-2 times out. If, on the other hand, the preset revolutions do not occur before IC-1 times out, power is not applied to the 115 volt outlet. Instead, the timers and counter are reset to zero. The second throw of the double-throw relay (RL-1) allows the lighting schedule to be monitored by any low voltage monitoring device. The unit described in Fig. 1 allows the running revolution criterion for "lights-on" to be as low as 2 rev/5 min or as high as 2560 rev/sec. Adding a resistor in series to R4 allows the time interval, during which counts are accumulated to meet the preset criterion, to be measured in hours rather than minutes or seconds. The duration of "lights-on" can be as short as I sec or as long as 5 minutes, but if a resistor is added in series to R5, the duration of "lights-on" may be lengthened into the range of hours depending on resister size

488

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FIG. 2. A 12.5 hour portion of a running wheel activity record in which running activity (heavy horizontal lines) and "'lights-on'" (faint horizontal lines) were recorded for eight days. "Lights-on" is indicated by an upward deflection of the recording pen. It is apparent that there is a very high correlation between running activity and "lights-on." The space between each heavy vertical line which transects the entire record represents 0.5 hour. The f'trst four days of the running activity and "'lights-on" records have been enhanced to aid visualization,

FEEDBACK LIGHTING

489 TABLE 1 PARTS LIST FOR FEEDBACK UNIT Parts List

Resistors R3 R6,RI2 R9,R10 RI ,R2,R7,R8,R 11 R4,R5* R13 RI4

270 OHMS 1 K OHMS 2.2 K OHMS 10 K OHMS 3 MEG OHMS with 5 Meg Potentiometer 52 OHMS 3 K OHMS

Capacitors C2,C8,C13,C17 C3,C9,C14,C15,C16 C7 C12 CI,C10 C6 Cll C5

0.01 MFD Disc 0.1 MFD Disc 0.047 MFD Disc 3.3 MFD 16V Electrolytic 50 MFD 16V Electrolytic 2200 MFD 25V Electrolytic 1000 MFD 25V Electrolytic 2200 MFD 16V Electrolytic

Integrated Circuits IC-1,1C-2 IC-3 IC-4 IC-5 1C-6 1C-7 IC-8 Other Components CR-1,CR-2,CR-3,CR-4,CR-5 TR-1 RL-1 T1 Fuse

555 Timer/Oscillator 7805 Voltage Regulator 7400 Quad 2-1nput POS NAND Gate 4040 12 Stage Binary/Ripple Counter 74193 Synchronous Up/Down 4 Bit Binary Counter-Dual Clock with Clear 74154 4-Line to 16-Line Decoder/Multiplexer 74123 Dual Retriggerable Monostable Multivibrators with Clear 1N4003 Diode 2N3904 Transistor Relay 4PDT 12 Volt Coil Transformer 115 to 12 Volts 2 AMP 3AG

*Potentiometers used to adjust maximum time period.

(the larger the resistor the greater the duration). The system can be adapted to many different situations. By reversing the "normally o p e n " / " n o r m a l l y closed" relay connections, the lighting schedule may be reversed so that the lights turn off whenever the rotation rate meets the criterion. This system can be linked to any animal behavior that can be monitored, provided an electronic impulse is produced each time the behavior is performed, for example drinking or eating. Any device powered by 115 volt A.C. can be plugged into the unit (limited only by size of relay used), therefore a multitude of different electronic devices may be controlled through a variety of monitored behaviors. APPLICATION The feedback lighting (LDrB), described here, is substantially different from previously used forms of animalcontrolled lighting [3, 7-15]. F o r example in self-selected lighting the animal must " l e a r n " to turn its cage lights on or to change its lighting intensity by depressing a bar. When utilized, some self-selected lighting systems elicited variable, aperiodic lighting schedules with "lights-on" ranging from a

few seconds a day to continuous light [7,11]. Moreover, most of the lighting schedules produced did not appear to illuminate the photosensitive portion of the circadian cycle entirely or exclusively [3, 7-15]. Another type of selfselected lighting is accomplished by having the animal free to roam from one connecting chamber to another, each with a different intensity of lighting [6]. This type of self-selected lighting produces a more natural circadian lighting schedule and thus allows animals to freerun. Rats exposed to our LDFB system maintain a freerunning rhythm of locomotor activity. Furthermore the period of the freerunning rhythm is directly proportional to the light intensity [5]. Despite the fact that rats in LDrB were exposed to light during their normal nocturnal activity period, they nevertheless maintained their normal rate of running. This rate, being above criterion, kept the lights on (Fig. 2). With LDrB we have obtained strong experimental evidence that the delay to advance ratio of the phase-responsecurve is important in determining the freerunning period of the circadian rhythm [5]. We have also been able to show that Aschoff's intensity effect [2] operates only within the

FERRARO.

490

STONE AND McC’ORMAC’li

defined photosensitive portion of the circadian cycle and that the Aschoff effect and anovulation can be produced with as little as 4 hr of light per circadian cycle [5]. Previous studies indicated that only LL or long photoperiods could produce these effects. Other areas wherein this system will be useful include: possible splitting of the locomotor activity rhythm

comparisons of delay to advance ratio5 ot the phaseresponse-curve with respect to the determination of the freerunning period, and making comparisons of entrainment strategies for diurnal vs. nocturnal animal\.

into two components, examining the photoperiodic effects of day length on reproductive function, making interspecies

We wish to acknowledge Dr. J. E. Lawler for assistance initial developmental phases of this feedback system.

ACKNOWLEDGEMEN

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