caudate nucleus lesion selectively increases paradoxical sleep episodes in the rat corsi, grinberg,...

7/28/2019 Caudate Nucleus Lesion Selectively Increases Paradoxical Sleep Episodes in the Rat Corsi, Grinberg, Arditti

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Physiology and Behavior, Vol. 14, pp. 7-11. Brain Research Publications Inc., 1975. Printed in the U.S.A.

Caudate Nucleus Lesion Selectively IncreasesParadoxical Sleep Episodes in the Rat

M . C O R S I - C A B R E R A , J . GRINBERG-ZYLBERBAUM AND L . S . ARDITTIL abora t ory o f P sychophys i o l og i ca l R esearch , P sych o l ogy Coll ege , Univers idad A n dhau cA par t ado P os t a l 10-844 Mdx i co 10 , D . F . , Mdx i co

(Received 26 June 1974)

CORSI-CABRERA, M., J. GRINBERG-ZYLBERBAUM AND L. S. ARDITTI. Caud ate nucle us lesion selective ly increasesparadoxical sleep episodes in the rat. PHYSIOL. BEHAV. 14(1) 7- 11 , 1975. - The EMG, ECG and the behavioralactivity of seven rats were recorded for three days previous to and 24 hours after lesiordng both caudate-putamencomplexes. Following the lesion, the paradoxical sleep stage lengthened by about 248%, without noticeable changes in theslow wave sleep or in the waking stages. The greatest increase was obtained with lesions placed in the mediomedial portionof the caudate-putamen complex. In other six rats submitted to the above procedure except that the lesions were placed inthe anterior cerebral cortex, and also in five more rats implanted in both caudate-putamen complexes but not lesioned, nochange was noted in the waking, paradoxical sleep or slow wave sleep stages.Caudate nucleus Paradoxical sleep Electrolytic lesion

EVIDENCE for an influence of the caudate nucleus (CN)on the regulation of the electrical activity of the cerebralcortex has been reported within the past few years. Itslesion produces an increase in the size of the cortical poten-tials evoked by thalamic stimulation [3], while theopposite effect follows its stimulation [4]. Furthermore,stimulation of the dorsolateral portion of the head of theCN inhibits the secondary components of the corticalpotentials evoked by visual, auditory and somatic stimula-tion without altering their primary components [7]. Thesefacts indicate an inhibitory influence of the caudate thatpossibly counteracts the thalamic and reticular formationactivities [ 2].On the other hand, it has been shown that high fre-quency stimulation of the CN produces cortical desynchro-nization and wakefulness while slow frequency stimulationof the same structure produces cortical synchronization andslow waves very similar to thos e recor ded during sleep [ 1 ].However there is no information concerning a possible roleof the CN in the sleep process though its inhibitory influ-ence on the electrical activity of the brain suggests thispossibility. In order to investigate whether suppression ofthis inhibitory action would modify some of the stages ofthe waking/sleep cycle, the following experiment s wereperformed.

METHODA n i m a l s

A total of 18 adult albino rats of either sex, 4 to 6

months old, were used. All were kept for at least 3 monthsin a semi-soundproof room, with an automatic controlwhich turned the l i g h t s on from 9 a.m. until 2 p.m. daily, inorder to induce a unifo rm waking-sleep cycle. At the end ofthis period the rats were randomly divided into the follow-ing three groups: A, caudate-putamen group (7 rats);B, cortex group (6 rats); C, control group (5 rats).P rocedure

Under pentobarbital anesthesia (40 mg/kg) and using thestereotaxic technique, all the rats were implanted asfollows: a midline longitudinal incision was made on theskin of the skull and after separating the periosteum, ascrew was ins erted 1.0 mm in each of two small holesdrilled in the left side 3.0 mm lateral to the midline, one atthe lambda level, and the other between this and thebregrna level. By means of these screws the electrocortico-graphic activity (ECG) was recorded. Two stainless steelsurgical clasps were clamped in the left nuchal muscle inorder to record electromiographic activity (EMG). Bipolarelectrodes made of stainless steel wire 0.3 mm in diameterand insulated except at the tip, were introduced in eachside through small holes drilled at the level of the bregma,3.0 mm from the midline. Their tip was placed 4.5 mmbelow the dura into the caudate-putamen complex, in therats of Groups A and C, and only 1.0 mm into the anteriorcerebral cortex in the animals of Group B. The electrodeswere cemented with acrylic to the exposed skull and theskin incision sutured. Penicillin (40,000 u/kg) was given


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8 CORSI-CABRERA, E T A L .

intramuscularly to each rat at the end of the surgicalprocedure.At least 3 to 4 days were allowed for complete recovery,and then the rats were introduced into a sound-proof,illuminated room and placed on a small elevated platformwhere they could move freely without jumping to the flooror escaping. By means of wires the four muscle andposterior cerebral cortex electrodes were attached to aspecial rotary connector and to a recording polygraph. ECGand EMG were recorded conti nuously from 10 a.m. until2 p.m. every day for 6 consecutive days.

In order to measure the mean voltage and frequency ofthe ECG and EMG activi ties, 10 ran dom samples of 5 seceach, were taken, for each stage of the sleep-waking cycle.The voltage was measured from the crest to the valley ofeach wave, the frequency was quantified counting howmany crests per sec appeared in each sample.On the third day, after complet ing the recording time,the CN was lesioned on both sides in the rats of Group Aand the anterior Cerebral cortex in the rats of Group B bypassing 3 mA direct current for 60 sec through each of thecorresponding electrodes. After 24 hr, the rats were intro-duced in the sound-proof room, in order to continue withthe recordings. No lesion was made in the rats of Group C.Waking, slow wave sleep and paradoxical sleep wereidentified by means of the polygraphic record and with the

aid of a closed circuit TV set that allowed the close observa-tion of the overt behavior of the animals. This permitteddetermi nation of the numbe r and length of each of theabove mentioned stages for each rat during the two three-day periods of the test. These determinations were doneusing the whole 4-hour recording without sampling it.These data were compared for each group by means of aStudent' s test [8] . The correlation coefficient [8] b etweenthe extent of the lesions made in the caudate-putamencomplex and the changes which it provoked on the sleepwaking cycle, was also calculated.At the end of the experiment, the animals were deeplyanesthetized and their brains were perfused with 10%Formalin solution, preceded by 50 ml of a 0.85% salinesolution. The brains were kept for one week in 40%Formalin solution after which tranverse frozen sections of50 ~ width were made. These s ections were used as nega-tives to make photographic prints [5], which with the aidof a planimeter permitted locating and measuring the sizeof the lesions.

RESULTSDuring wakefulness, the rats of the three groups showeda desynchronized ECG activity with predominant fre-quencies of 8 to 10 Hz and amplitudes of 50 to 150 ++V.

.,,.,. I, . m . , , . . t + , , , , ~ . . , L J J , . .. + i , ,m i , + m , ~ J . , , , , A t . + ~ + , ~ . , ~ t . l t m ~ , , . ~ , , ~ . + : ~ + ' ~ i ~F..c:Otm l m , ' W I R ~ , . + .,,,,. + ..+,.,,+., . . + .r-. ~ ~ : ' ~ " + ". k ' J l d ~ " - , I + L + + + + L ~+ ++,e : ;l + + + - + - " , ~r

B

C l t , : P+ + + t ~ , ! + i i , ~ ,

D- - . - . . ~ m m . t ~ , . L . m a , L ~ a , ~ u - , . m , l = . J ~ , , J " ' " " zt ~ ( , : . ~ , t ~ . . . l . r . . , ~ m . l . m , m ~ , m , , ~ , . , ~ p q m ~ ' , t m *E . H G z

5 s e c o n d s50pv

FIG. 1. The four stages of the waking-s leep cycle of the rat. Typical electrocorticographic (ECG) and electro-miographic (EMG) records during A attentive wakefulness. B relaxed wakefulness. C slow wave sleep and Dparadoxical sleep. Note the decrease in the EMG activity from A to D and the similarity o f the ECG activity inattentive wakefulness and paradoxical sleep.


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CAUDATE NUCLEUS AND PARADOX ICAL SLEEP 9

%t 6 01 4 0 .120-tOO.8 0 .60 ., tO.2 0 .0

- 2 0 .- 4 0 .

Wake f u l n e s s

U I I I

S/ow s /eep

r-1

P a r a d o x i c a l s l e ep

II

C o r tr n e

%.~;0.1~0. 1 2 0,100,8 060.~02 0

FIG. 2. Each bar represents the relative duration (percent) of time that the three groups of rats spent inwakefulness, slow sleep and paradoxical sleep during the last three days of recording. The percent was calcu-lated by taking as 100% (0 horizontal line) the total time that the rats spent in the three stages during the firstthree days of recording. Only the increase (148%) in the paradoxical sleep stage of the eaudate-putamencomplex lesioned group of rats (white bars) was statisticaUy significant (t = 5.47, p = 0.01).

The EMG activity was of high amplitude, average 50 to125 uV, and varied considerably in close correlation withthe rat's motor activity. When the rat directed its attentionto something in its environm ent, the ECG activity becamesynchronized and regular, with a frequency of 7 Hz (thetarhyt hm) (Fig. 1, A and B). It is interesting to note thatthese characteristics are different in terms of frequency andrhythm from the ones obtained in humans and in cats[9,10].During slow wave sleep, no movements were observed inthe rat and the ECG showed a great increase in amplitude(average 350 uV) and the typica l slow wave bursts inter-mingled with slow waves of 6 to 8 Hz. The EMG voltagedecreased con sidera bly, average 50 to 18 uV (Fig. 1, C).The paradoxical sleep stage appeared among slow wavesleep episodes, and was signaled by a typi cal behavioralcomponent, i.e. a change of the posture of the rat whichnodded its head and curled up. At the same time the EMGactivity disappeared entirely, becomin g an isopotential line.The ECG showed the appeara nce of a synchroniz ed thetarhyth m of e xactly 7 Hz very similar to, but more regular thanthe one record ed dur ing the att entiv e behavior (Fig. 1, D).No noticeable changes in the frequency and morphologyof the EMG and the ECG were noticed after the caudate-putamen or the cerebral cortex lesions, and though thetotal time that each rat spent in the waking stage decreased

during the last three days of recording (Fig. 2), the differ-ences with the figures obtained during the first three days,were n ot stat istically significant (Gro up A: t = 2.45, p =0.10; Group B: t = 1.88, p = 0.10 and Group C: t = 0.24, p= 0.20) (see Table 1).Again, the t o t a l time that the three groups of rats spentin slow wave sleep stage increased during the last three daysof recording (Fig. 2), but the differences, in relation withthe first three days, were not sta tistically significant either(Group A: t = 1.54, p = 0.20; Group B: t = 2.50, p = 0.10and Group C: t = 0.20, p = 0.90) (see Table 1).Similarly there were no significant differences in thenumber and the length of waking and slow wave periodsexhibited by the rats of the three groups, during the sixdays of recording (see Table 1).In contrast, the total time that the rats of Group A spentin the paradoxical sleep stage increased from an average of381.16 sec to 958.37 sec following the cauda te-put amenlesion (Fig. 2) an d this consid erable increase was statis-tically significan t (t = 5.47, p = 0. 01) (see Tabl e 1). It wasalso noted an increase from the first day to the third dayfollowing the lesion, this increment was statistically signifi-cant (from 6.38% during the first day, to 9.56% during thethird day, t = 3.81, p = 0.01). This change was funda-mentally due to an increase in the number of periods ofparadoxical sleep in these rats (from an average of 4 before


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10 CORSI-CABRERA, ET AL.

TAB LE1PERCENTAGE OF THE TOTAL TIME AND THE NUMBER OF EPISODES THAT THE CEREBRAL CORTEX, CAUDATE PUTAMENNUCLEUS AND CONTROL GROUPS OF RATS SPENT IN EACH STAGE OF THE SLEEP-WAKING CYCLE, IN THE FIRST AND LASTTHREE DAYS OF RECORDING

Wakefulnessfirst 3 days last 3 days

Mean S.D. Mean S.D.

Slow wave sleep Paradoxical sleepfirst 3 days last 3 days first 3 days last 3 days

Mean S.D. Mean S.D. Mean S.D. Mean S.D.

ControlPercent 36.64 10.94 32.36 5.77 52.40Number of episodes 21.36 3.71 19.84 4.80 25.61

Caudate-Putamen lesionPercent 49.36 43.41 38.90 9.34 44.46Number of episodes 28.71 4.08 30.27 8.72 29.66

Cerebral cortex lesionPerce nt 44.93 5.54 43.73 8.46 55.58Number of episodes 28.59 6.30 33.70 1.88 30.79

8.32 59.51 5.79 7.33 3.23 8.16 2.652.88 26.25 2.28 8.50 4.28 7.97 3.55

5.11 49.81 6.77 3.16" 1.40 7.86* 2.465.09 35.88 10.51 4.19" 1.65 11 .43" 4.05

6.29 56.57 14.99 3.06 .85 4.31 1.416.30 32.49 1.20 5.39 3.65 5.03 2.27

*is the 0.01 level of stat istical significance betwe en differences.

C . 1 1 . . . . . . . . . . . . . . . . . . . . . . . 2

C .N . 18FIG. 3. Histological sections showing the c ortical lesions in t wo rats (C.C. 1 and 2) and the largest caudate-putame n complexlesions in other t wo rats. (C.N. 18 and 20).


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CAUDATE NUCLEUS AND PARADOXICA L SLEEP 11

to 11 after the lesion, t = 4.30, p = 0.01) and o nly partl y asa result of an increase in the length of each episode (t =2.49, p = 0.05) (see Table 1). This means that the incre-ment in the frequency of the episodes is not correlated witha shorter du ration of each of them because both sufferedincrement.This result is more significant since the increase in dura-tion and number of the paradoxical sleep periods in the ratswith a cerebral cortex lesion and in the nonlesioned ratswas not s tatisti cally signi ficant (Gro up B: t = 0.62, p =0.60; Group C: t = 0.23, p = 0.90) (see Table 1).The histological analysis showed that the most pro-nounced increase in the paradoxical sleep stage wasobtained with lesions placed in the medio-medial portion ofthe cau date-put amen comple x (Fig. 3). Similar medio-medial lesions were obtained in 4 of the 7 rats of the group;the other three had dorsomedial lesions.Furthermore, the correlation coefficient between thesize of the lesions and the increase in the paradoxical sleepstage was not significant (r = .03), indicating that in theproduction of the observed changes, the location was moreimpor tant than the extent of the lesion, because in themedio-medial lesioned rats the increments were morepronounced.

because neither the waking stage nor the slow wave sleepstage undergo modifications after the caudate lesions. Thefact that the paradoxical sleep stage increment was notreflected in a correspondent decrement in the other stages,is understandable if we consider that the total time that therats spent in paradoxical sleep is minimal compared to thetime spent in the other stages. Furthermore, the observedchanges consisted fundamentally in an increase in thenumber of periods of paradoxical sleep and only partly inan increase of the length of each period, This result indi-cates that perhaps the caudate does not act on themechanisms which maintain the paradoxical sleep, rather itpossibly exerts an inhibitory control on the mechanismsthat trigger the onset of the paradoxical stages [6]. Themedio-medial portion of the caudate nucleus could bepointed out as the site of this inhibito ry control, becausethe greatest changes were observed after lesioning thisregion.

The fact that no significant changes were observed in theimplanted but not lesioned rats and in the cerebral cortexlesioned rats, indicates that the result obtained in thecaudate-putamen complex lesioned group are not due tothe surgical procedure nor t o a nonspecific lesion, nor to anhabituation to the stereotype either.

DISCUSSIONThese findings underline the important participation ofthe caudate nucleus in the sleep processes, which appearsfundamen tally and s electively related to the paradoxi calsleep stage. This selective participation is very obvious

ACKNOWLEDGEMENTSThe authors express their gratitude to Prof. Dr. Alberto GuevaraRojas for his critical analysis of the manuscript and to Mr. LouisChauvet for his help in its redaction.

REFERENCES

1. Buchwald, N. A., F. E. Horvath, S. Soltysik and C. RomeroSierra. Inhibitory responses to basal ganglia stimulation. Boln .Ins t . mbd. biol . Mex. 22: 363-377, 1964.2. Demetreseu, M., M. I)metrescu and G. Iosif. The tonic controlof cortical responsiveness by inhibitory and facilitatory diffuseinfluences. Electroenceph. cl in. Neurophysiol . 18: 1-24, 1965.3. Demetrescu, M. Ascending inhibitory and facilitatory influ-ences controlling primary thalamo-cortical responsiveness.Brain Res . 6: 36-47, 1967.4. Demetrescu, M. and M. Demetrescu. The inhibitory action ofthe caudate nucleus in cortical primary receiving areas in thecat. Electroenceph. cl in. Neurophysiol . 14: 37-52, 1962.5. Guzm~in-Flores, C., M. Alcaraz and A. FernAndez. Rapid proce-dure to localize electrodes in experimental neurophysiology.Boln. Es t . reed. biol. Mex. 16: 29-31, 1968.

6. Jouvet, M. Recherches sur les structures nerveuses et lesmecanismes responsables des differentes phases du sommeilphysiologique. Archs ital. Biol. 100: 125-206, 1962.7. Krauthamer, G. and D. Albe-Fessard. Inhibition of nonspecificsensory activities following striopallidal and capsular stimula-tion. ~ Neurophys io l . 28: 100-124, 1965.8. McGuigan, F. J. Exp erime ntal Psychology. A Meth odogica lApproach . Second Edition. Prentice-Hall Inc., 1968.9. Swisher, J. N. Manifestations of "act ivated" sleep in the rat.Science 138: 1110, 1962.10. Takeuchi, E. Polygraphical study on the wakefulness sleepcycle of the rat. Jap. J. Psychol. 41: 248-256, 1970.

caudate nucleus lesion selectively increases paradoxical sleep episodes in the rat corsi, grinberg,...

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