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Changes in acetylcholinesterase activity in hippocampus produced by septal lesions in the rat
Life Sciences Vol. 12, Part I, pp . 261-270 Printed in Great Britain
Pergamon Press
CHANGES IN ACETYLCHOLINESTERASE ACTIVITY IN HIPPOCAMPUS PRODUCED BY SEPTAL LESIONS IN THE RAT
Bolek Srebro, Barbara Oderfeld-Nowak, Irena giodoe, Jadwiga Dekbrowska and Olgierd Narkiewioz3
Nenoki Institute of Experimental Biology, Pasteur 3 Warsaw 22, Poland
(Received 20 June 1972 ; in final form 8 January 1973) summary The ACbE activity of the hippooampus after septal lesions was determined . The activity of this enzyme in hippooampus depends on the site and extent of lesion and on the survival time after surgery . A very strong decrease of ACNE is observed after large lesions which involved most of the septum ; slightly less effective are lesions placed in the medial septal nuclei including a part of the vertical limb of the diagonal band of Brooa. No effect on ACNE activity in the hippooampus is observed when the lateral septal nuclei are damaged . ACh$ decreases rapidly in the course of the first 4 to 6 days after surgery and remains afterwards on a low level . The fall in the hippooampal ACNE ooinoidea with the expected rate of degeneration of septohippooampal fibres and their terminals . Functional relationships between the septum and other limbio structures have been demonstrated in several behavioral studies (3, 7, 11, 16, 23) . It has been recently shown that either cholinergio stimulation or blockade of the septum and 1 . Present address : University of Bergen, Norway 2 . To whom requests for reprints should be sent 3 . Permanent address : Medical School, Gdafisk, Poland 261
262
AChE in the Hippocampus after Septal Lesions
Vol. 12, No. 6
amygdala results in some of the behavioral dysfunctions observed after lesions in these areas (12, 13, 14, 15) . On the other hand, antioholinergio drugs have been reported to produce behavioral deficits similar in some respect to those observed after lesions of the hippooampus and septum (1, 4, 8, 9, 17,23) . Histoohemioal methods have provided a detailed localisation of aoetyloholinesterase (ACbH) in the hippooampal region and amygdala of the rat (22, 25) as well as in a fiber system projecting from the septum to the hippooampus (20) . Some authors (18) have even suggested that there are so-called oholinergio fibers of the medial cortex originating in the septal area and that some septal nuclei might constitute as important part . of the cholinergio system of the forebrain . Since septal nuclei are reciprocally connected with the hippooampal structures (5, 26, 27) lesions of the septum were made in order to trace the changes in ACNE activity of the hippooampus . The results are presented in this communication . Me those The animals used were male Wistar rats, bred in the Nenoki Institute . Body weights ranged from 220 to 280 g and the ages from 4 to 6 months . In 58 animals, bilateral septal lesions were made using a stereotaxio instrument, by passing anodal current (2 mA/sec) through a platinum electrode (0,2 mm diameter), insulated except for the tip (0,4 mm) . Sodium pentobarbital anaesthesia (55 mg/kg i .m .) was used . The same anaesthesia was given to 55 control animals but no operation was performed; in 3 animals lesions placed above the septal area were performed as a control .
Vol. 12, No . 6
AChE in the Hippocampus after Septal Lesions
26 3
De Groot's atlas (6) provided the coordinates for all the lesions . After the operation each animal was placed in an individual cage . Postoperative changes in behavior were evaluated in all animals 24 and 48 h after surgery . Survival time of the rats was 2-90 days after the operation . The rats, either conscious or slightly anaesthesized with ether, were killed by decapitation . The brain was removed from the skull, frozen and dissected . The hippocampus together with the gyrus dentatus was removed by dissecting it free of the entorhinal cortex and removing the fornix and fimbria . The whole procedure took less than five minutes . Each piece of dissected tissues was weighed and stored at +4 0C in a small jar for approximately 2 h before the biochemical analyses were performed . Previous experiments have shown that this procedure does not affect AM activity . The ACNE activity of the hippooampus in operated as well as in unoperated animals was estimated in the homogenates of the dissected tissue . Corresponding structures from both sides of the same brain were analysed together . The homogenization and incubation procedures were the same as described previously (21) . Briefly, aoetylthiooholine (AThCh) was used as a substrate, and DFP (di-isopropyl-fluorophosphate) in a concentration of 1 x iO -'BM was used for inhibition of pseudooholinesterase activity . Sulfhydryl groups released from AThCh during incubation were estimated according to Ellman et al . (10), after inhibition of the enzymatic reaction with eserine (4 .5 x 10 3M) . In all rats in which septal lesions were made the anterior part of the brain together with septum was separated by a deep frontal out, placed in 1096 neutral formaline and subjected to
26 4
AChE in the Hippocampus after Septal Lesions
Vol . 12, No . 6
histological verification with Nissl and Klüver-Barrera methods . Extent of the lesions was plotted on the appropriate diagram of the septum .
Results The enzymatic activity of the hippooampus in unoperated animals showed very little variation, due probably to comparatively well defined borders of this structure which make it easy to dissect. it from the rest of the brain. The mean value of ACNE activity found by us on 55 unoperated rats, expressed as ymoles of AThCh hydrolysed h/g of fresh tissue of the hippooampuz was 428 ± 8, and the mean weight of the hippooampus was 53 ± 2 mg . Experimental material was divided into four groups according to the site and extent of the lesions . Typical examples of these groups are shown in the Fig 1 . Figure 2 presents changes in ACNE activity of the hippocampus two days after the lesions within the septum . In this period of time behavioral changes - increased startle reaction, cataleptic postures, attacking of an approaching object and vicious resistance to handling-seem to be most clearly expressed . Two days after the surgery, dorsal lesions involving almost exclusively the lateral septal nuclei did not result in a detectable changes of the enzymatic activity . Sham lesions placed in the oingular cortex and corpus oallosum produced similar results . However, ventral septal lesions, with damaged mostly the medial septal nuclei including part of the vertical limb of the diagonal band of Brooa, resulted in a significant decrease of 20 to 2796 of ACNE activity (p < 0 .01, t-test, two-tailed) . This decrease was even greater, up to 40-4596
Vol . 12, No. 6
AChE in the Hippocampus after Septal Lesions
265
(p < 0 .001, test as above), when the lesions were larger and involved most of the septum .
Fig 1 Typical localization of lesions in various groups of rats plotted on frontal sections of the septum . Crosshatohes mark the extent of lesion . IS-lateral septal nuclei, MS-medial septal nuclei, a-dorsal septal lesion restricted mainly to the lateral septal nuclei, b-ventral septal lesion damaging mostly medial septal nuclei including the vertical limb of the diagonal band c-large septal lesion, d -lesion above the septum tin the oingular gyros and corpus oallosum)
Figure 3 presents changes in ACNE activity in the hippocampus after large septal lesions at various periods of time after the surgery . AChl decreases rapidly in the course of the first few days and then remains at a low level . Two days after septal lesions the values of ACNE were significantly lower (p < 0 .001, test as above) and a further significant drop was observed
266
ACNE in the Hippocampus after Septal Lesions
Vol . 12, No. 6
of control value 100
75 50 25
Fig 2 ACbB activity in the hippooampus two days after septal lesions . En$yme activity is expressed as a percentage of the respective control values . The standard errors of the means are indicated : a-dorsal septal lesions restricted mainly to the lateral septal nuclei, n-3 ; b-ventral septal lesions damaging mostly medial septal nuclei including the vertical limb of the diagonal band, n-19 ; o-large septal lesions n-7' d-lesions placed above the septum tin Ue oingular gyrus and corpus oallosum), n-3 aftea four to six days . There were no evident changes for the longer survival periods ; the values of ACNE were around or below 23% of control values .
Vol. 12, No . 6
AChE in the Hippocampus after Septal Lesions
of control value
75 50
b
25
2
4-6
10-21
42 90 Days after, surgery
Fig 3 ACNE activity in the hippocampus at various survival periods after large septal lesions . Enzyme activity is expressed as a percentage of the respective control values . The standard errors of the means are indicated (2 days n=7 ; 4-6 days, n=11 ;" 10-20 days, n=6 ; 90 days, n = 3) . The weight of hippooampus was generally unchanged in all operated animals despite the great decrease of AChE activity . Mean weights of the hippocampi were after : 2 days of animal survival 57 ± 2 mg, 4-6 days 52 ± 1 mg, 10-21 days 52 ± 2 mg, 42 days 50 2 3 mg, 90 days 52
1
2 mg .
267
288
ACNE in the Hippocampus after Septal Lesions
Vol. 12, No . 8
Activity of LDH-enzyme, regarded as a "neutral marker" (measured in the same homogenates in which AChE activity estimations were performed), was unchanged when compared with the control values in all survival periods (K . Kowalska, personal communication) .
Discussion Most of the experimental material was concerned with the effects of septal lesions on ACNE activity in the hippooampus after very short survival times (2-~4 days), because it was observed previously (2,28) that the behavioural changes were expressed most clearly during this period . The most effective septal lesions included an area where the fibers of the septohippooampal projection have been described as arising (20) . The fall in the hippooampul ACNE reported here coincides with the expected rate of degeneration of the septohippooampal fibers and their terminals . However, it is not yet possible to decide whether the only secondary fiber degeneration is responsible for ACNE activity changes in the hippocampus . To elucidate the nature of these changes more detailed studies are in progress . It has been demonstrated previously that ACNE (determined histoohemioally) and CbAc decrease in the hippooampus of rat after interruption of fibers of the fimbria (19), and that ChAo activity falls after lesions of the septum of oat (24) . The present study, using a biochemical method for ACNE estimation together with evaluation of site and extent of the lesion, provides additional evidence for precise septal control of the enzyme involved in acetylcholine metabolism in the hippocampus .
Vol. 12, No . 6
269
AChE iri the Híppocampus after Septal Lesions Aoknowledgements
We thank with pleasure Professor S . Niemierko for her critioism and advioe and Dr . H. Ursin and Mr . H.M . Allen for their help during the preparation of the manusoript . Mrs . B. Heiler-Go2:Qbiewskats skilful teohnioal assistanoe is greatly appreoiated . ReferenQees G . BIGNAMI, Prooesdings of the Vth International Congress of the Collegium Internationale Neuropsyohopharmaool
oum ,
Washington, D.C ., 1966, Exoerpta Medioa, I .C .S ., Amsterdam, 12U, 819-830 (1967) . 2 . J .V . BRADY and W .J .H . NAUTA, J.oomp.physiol .Psyohol . 46, 339-34.6 (1953) . 3 . J . BRÜGGE, Electroencephal . olio . Neurophysiol . 18, 36-44 (1965) . 4 . P .L . CARLTON, Reinforoement: Current Researoh and Theories , Aoademio Press, New York, 286 (1969) . 5 . W .M . COWAN, G . RAISMAN and T .P .S . POWELL, J .Neuro . Neurosurg, Psychiat . 28, 137-151 (1965) . 6 . J . DE GR00T, Verh .kon .ned .Akad .Wet . L2, 1-40 (1969) . 7 . P .J . DONOVICK, J .oomp.physiol .Ps, oyhol . 66, 569-578 (1968) . 8 . R.J . DOUGLAS and R.L . ISAACSON, Psyohon .Soi . 4, 283-284 (1966) . 9 . R.J . DOUGLAS and A .C . RAPHEISON, J .oomp.Ph9siol .Psjvohol. 62, 320-330 (1966) . G .L . ELLMAN, N.D . COURTNEY, V . ANDRES and R.M . FEATHERSTONE, Bi ochem .Pharmaool . Z, 88-95 (1961) . G .V . GODDARD, Psvehol .Bull . 62, 89-109 (1964) .
270
AChE in the Hippocampus after Septal Lesions
Vol . 12, No. 6
12 . G .V . GODDARD, J . comp .physiol .Psyohol . 68, 2, part 2, 1-18 (1969) . 13 . J .A . GRAY, Psychol . Rev. ZZ, 456-480 (1970) . 14 . S .P . GROSSILAN', J.oomn .Physiol .Psyohol . 2§, 194-200 (1964) . 15 . L.W . HAMILTON, R.A . Mo CLEARY and S .P . GROSSMAN, J Com . Rhysiol . Ps oh
. 66, 563-568 (1968) .
16 . P . KARLI, ~. Ph3"siol . (Paris) , 60 Suppl. 1, 3-148 (1968) . 17 . D.P . KIMBLE and R.J . KD03LE, J .oomP .p bjvsiol .Psyohol . 6Q, 474-"476 (1965) . 18 . K. KRNJEVIC and A . SILVER, J . Anat . 100, 63-89 (19667 . 19 . P .R . LEWIS, C .C .D . SHIITE and A . SILVER, J . P
si
. 1.21,
215-224 (1967) . 20 . P .R . LEWIS and C .C .D . SHIITE, Brain. 20, 521-540 (1967) . 21 . L. LUBINSKA, S . NIEMIERKO, B . ODERFELD and L. SZWARC, J.Neuroohem . 10, 25-41
(1963) .
22 . J.S . MATHISEN and T .W . BLACKSTAD, Aota anat . ~j, 216-253 (1964) . 23 . R.A . Mo CLEARY, Progress in Physiologioal psychology , Academio Press, New York, (1966) . 24 . E .G . MoGEER, J .A . WADA, A . TERGO and E . JUNG, ExDtl . Neurol . 227-284 (1969) . 25 . L. NITECSA, 0. NARKIEWICZ and H. ZAWISTOWSKA, Aota Neurobiol. =. 31 , 383-388 (1971) . 26 . H. PETSCHE, C . STUMPF and G . GOGOLAK, Eleotroenoephal .olin. Neurophysiol . 14, 202-211 (1962) . 27 . G . RAISMAN, W .M . COWAN and T.P .S . POWELL, Brain . U, 83-108 (1966) . 28 . B .H . TURNER, J . oomp .physiol .Psychol . 7, 103-113 (1970) .
Pergamon Press
CHANGES IN ACETYLCHOLINESTERASE ACTIVITY IN HIPPOCAMPUS PRODUCED BY SEPTAL LESIONS IN THE RAT
Bolek Srebro, Barbara Oderfeld-Nowak, Irena giodoe, Jadwiga Dekbrowska and Olgierd Narkiewioz3
Nenoki Institute of Experimental Biology, Pasteur 3 Warsaw 22, Poland
(Received 20 June 1972 ; in final form 8 January 1973) summary The ACbE activity of the hippooampus after septal lesions was determined . The activity of this enzyme in hippooampus depends on the site and extent of lesion and on the survival time after surgery . A very strong decrease of ACNE is observed after large lesions which involved most of the septum ; slightly less effective are lesions placed in the medial septal nuclei including a part of the vertical limb of the diagonal band of Brooa. No effect on ACNE activity in the hippooampus is observed when the lateral septal nuclei are damaged . ACh$ decreases rapidly in the course of the first 4 to 6 days after surgery and remains afterwards on a low level . The fall in the hippooampal ACNE ooinoidea with the expected rate of degeneration of septohippooampal fibres and their terminals . Functional relationships between the septum and other limbio structures have been demonstrated in several behavioral studies (3, 7, 11, 16, 23) . It has been recently shown that either cholinergio stimulation or blockade of the septum and 1 . Present address : University of Bergen, Norway 2 . To whom requests for reprints should be sent 3 . Permanent address : Medical School, Gdafisk, Poland 261
262
AChE in the Hippocampus after Septal Lesions
Vol. 12, No. 6
amygdala results in some of the behavioral dysfunctions observed after lesions in these areas (12, 13, 14, 15) . On the other hand, antioholinergio drugs have been reported to produce behavioral deficits similar in some respect to those observed after lesions of the hippooampus and septum (1, 4, 8, 9, 17,23) . Histoohemioal methods have provided a detailed localisation of aoetyloholinesterase (ACbH) in the hippooampal region and amygdala of the rat (22, 25) as well as in a fiber system projecting from the septum to the hippooampus (20) . Some authors (18) have even suggested that there are so-called oholinergio fibers of the medial cortex originating in the septal area and that some septal nuclei might constitute as important part . of the cholinergio system of the forebrain . Since septal nuclei are reciprocally connected with the hippooampal structures (5, 26, 27) lesions of the septum were made in order to trace the changes in ACNE activity of the hippooampus . The results are presented in this communication . Me those The animals used were male Wistar rats, bred in the Nenoki Institute . Body weights ranged from 220 to 280 g and the ages from 4 to 6 months . In 58 animals, bilateral septal lesions were made using a stereotaxio instrument, by passing anodal current (2 mA/sec) through a platinum electrode (0,2 mm diameter), insulated except for the tip (0,4 mm) . Sodium pentobarbital anaesthesia (55 mg/kg i .m .) was used . The same anaesthesia was given to 55 control animals but no operation was performed; in 3 animals lesions placed above the septal area were performed as a control .
Vol. 12, No . 6
AChE in the Hippocampus after Septal Lesions
26 3
De Groot's atlas (6) provided the coordinates for all the lesions . After the operation each animal was placed in an individual cage . Postoperative changes in behavior were evaluated in all animals 24 and 48 h after surgery . Survival time of the rats was 2-90 days after the operation . The rats, either conscious or slightly anaesthesized with ether, were killed by decapitation . The brain was removed from the skull, frozen and dissected . The hippocampus together with the gyrus dentatus was removed by dissecting it free of the entorhinal cortex and removing the fornix and fimbria . The whole procedure took less than five minutes . Each piece of dissected tissues was weighed and stored at +4 0C in a small jar for approximately 2 h before the biochemical analyses were performed . Previous experiments have shown that this procedure does not affect AM activity . The ACNE activity of the hippooampus in operated as well as in unoperated animals was estimated in the homogenates of the dissected tissue . Corresponding structures from both sides of the same brain were analysed together . The homogenization and incubation procedures were the same as described previously (21) . Briefly, aoetylthiooholine (AThCh) was used as a substrate, and DFP (di-isopropyl-fluorophosphate) in a concentration of 1 x iO -'BM was used for inhibition of pseudooholinesterase activity . Sulfhydryl groups released from AThCh during incubation were estimated according to Ellman et al . (10), after inhibition of the enzymatic reaction with eserine (4 .5 x 10 3M) . In all rats in which septal lesions were made the anterior part of the brain together with septum was separated by a deep frontal out, placed in 1096 neutral formaline and subjected to
26 4
AChE in the Hippocampus after Septal Lesions
Vol . 12, No . 6
histological verification with Nissl and Klüver-Barrera methods . Extent of the lesions was plotted on the appropriate diagram of the septum .
Results The enzymatic activity of the hippooampus in unoperated animals showed very little variation, due probably to comparatively well defined borders of this structure which make it easy to dissect. it from the rest of the brain. The mean value of ACNE activity found by us on 55 unoperated rats, expressed as ymoles of AThCh hydrolysed h/g of fresh tissue of the hippooampuz was 428 ± 8, and the mean weight of the hippooampus was 53 ± 2 mg . Experimental material was divided into four groups according to the site and extent of the lesions . Typical examples of these groups are shown in the Fig 1 . Figure 2 presents changes in ACNE activity of the hippocampus two days after the lesions within the septum . In this period of time behavioral changes - increased startle reaction, cataleptic postures, attacking of an approaching object and vicious resistance to handling-seem to be most clearly expressed . Two days after the surgery, dorsal lesions involving almost exclusively the lateral septal nuclei did not result in a detectable changes of the enzymatic activity . Sham lesions placed in the oingular cortex and corpus oallosum produced similar results . However, ventral septal lesions, with damaged mostly the medial septal nuclei including part of the vertical limb of the diagonal band of Brooa, resulted in a significant decrease of 20 to 2796 of ACNE activity (p < 0 .01, t-test, two-tailed) . This decrease was even greater, up to 40-4596
Vol . 12, No. 6
AChE in the Hippocampus after Septal Lesions
265
(p < 0 .001, test as above), when the lesions were larger and involved most of the septum .
Fig 1 Typical localization of lesions in various groups of rats plotted on frontal sections of the septum . Crosshatohes mark the extent of lesion . IS-lateral septal nuclei, MS-medial septal nuclei, a-dorsal septal lesion restricted mainly to the lateral septal nuclei, b-ventral septal lesion damaging mostly medial septal nuclei including the vertical limb of the diagonal band c-large septal lesion, d -lesion above the septum tin the oingular gyros and corpus oallosum)
Figure 3 presents changes in ACNE activity in the hippocampus after large septal lesions at various periods of time after the surgery . AChl decreases rapidly in the course of the first few days and then remains at a low level . Two days after septal lesions the values of ACNE were significantly lower (p < 0 .001, test as above) and a further significant drop was observed
266
ACNE in the Hippocampus after Septal Lesions
Vol . 12, No. 6
of control value 100
75 50 25
Fig 2 ACbB activity in the hippooampus two days after septal lesions . En$yme activity is expressed as a percentage of the respective control values . The standard errors of the means are indicated : a-dorsal septal lesions restricted mainly to the lateral septal nuclei, n-3 ; b-ventral septal lesions damaging mostly medial septal nuclei including the vertical limb of the diagonal band, n-19 ; o-large septal lesions n-7' d-lesions placed above the septum tin Ue oingular gyrus and corpus oallosum), n-3 aftea four to six days . There were no evident changes for the longer survival periods ; the values of ACNE were around or below 23% of control values .
Vol. 12, No . 6
AChE in the Hippocampus after Septal Lesions
of control value
75 50
b
25
2
4-6
10-21
42 90 Days after, surgery
Fig 3 ACNE activity in the hippocampus at various survival periods after large septal lesions . Enzyme activity is expressed as a percentage of the respective control values . The standard errors of the means are indicated (2 days n=7 ; 4-6 days, n=11 ;" 10-20 days, n=6 ; 90 days, n = 3) . The weight of hippooampus was generally unchanged in all operated animals despite the great decrease of AChE activity . Mean weights of the hippocampi were after : 2 days of animal survival 57 ± 2 mg, 4-6 days 52 ± 1 mg, 10-21 days 52 ± 2 mg, 42 days 50 2 3 mg, 90 days 52
1
2 mg .
267
288
ACNE in the Hippocampus after Septal Lesions
Vol. 12, No . 8
Activity of LDH-enzyme, regarded as a "neutral marker" (measured in the same homogenates in which AChE activity estimations were performed), was unchanged when compared with the control values in all survival periods (K . Kowalska, personal communication) .
Discussion Most of the experimental material was concerned with the effects of septal lesions on ACNE activity in the hippooampus after very short survival times (2-~4 days), because it was observed previously (2,28) that the behavioural changes were expressed most clearly during this period . The most effective septal lesions included an area where the fibers of the septohippooampal projection have been described as arising (20) . The fall in the hippooampul ACNE reported here coincides with the expected rate of degeneration of the septohippooampal fibers and their terminals . However, it is not yet possible to decide whether the only secondary fiber degeneration is responsible for ACNE activity changes in the hippocampus . To elucidate the nature of these changes more detailed studies are in progress . It has been demonstrated previously that ACNE (determined histoohemioally) and CbAc decrease in the hippooampus of rat after interruption of fibers of the fimbria (19), and that ChAo activity falls after lesions of the septum of oat (24) . The present study, using a biochemical method for ACNE estimation together with evaluation of site and extent of the lesion, provides additional evidence for precise septal control of the enzyme involved in acetylcholine metabolism in the hippocampus .
Vol. 12, No . 6
269
AChE iri the Híppocampus after Septal Lesions Aoknowledgements
We thank with pleasure Professor S . Niemierko for her critioism and advioe and Dr . H. Ursin and Mr . H.M . Allen for their help during the preparation of the manusoript . Mrs . B. Heiler-Go2:Qbiewskats skilful teohnioal assistanoe is greatly appreoiated . ReferenQees G . BIGNAMI, Prooesdings of the Vth International Congress of the Collegium Internationale Neuropsyohopharmaool
oum ,
Washington, D.C ., 1966, Exoerpta Medioa, I .C .S ., Amsterdam, 12U, 819-830 (1967) . 2 . J .V . BRADY and W .J .H . NAUTA, J.oomp.physiol .Psyohol . 46, 339-34.6 (1953) . 3 . J . BRÜGGE, Electroencephal . olio . Neurophysiol . 18, 36-44 (1965) . 4 . P .L . CARLTON, Reinforoement: Current Researoh and Theories , Aoademio Press, New York, 286 (1969) . 5 . W .M . COWAN, G . RAISMAN and T .P .S . POWELL, J .Neuro . Neurosurg, Psychiat . 28, 137-151 (1965) . 6 . J . DE GR00T, Verh .kon .ned .Akad .Wet . L2, 1-40 (1969) . 7 . P .J . DONOVICK, J .oomp.physiol .Ps, oyhol . 66, 569-578 (1968) . 8 . R.J . DOUGLAS and R.L . ISAACSON, Psyohon .Soi . 4, 283-284 (1966) . 9 . R.J . DOUGLAS and A .C . RAPHEISON, J .oomp.Ph9siol .Psjvohol. 62, 320-330 (1966) . G .L . ELLMAN, N.D . COURTNEY, V . ANDRES and R.M . FEATHERSTONE, Bi ochem .Pharmaool . Z, 88-95 (1961) . G .V . GODDARD, Psvehol .Bull . 62, 89-109 (1964) .
270
AChE in the Hippocampus after Septal Lesions
Vol . 12, No. 6
12 . G .V . GODDARD, J . comp .physiol .Psyohol . 68, 2, part 2, 1-18 (1969) . 13 . J .A . GRAY, Psychol . Rev. ZZ, 456-480 (1970) . 14 . S .P . GROSSILAN', J.oomn .Physiol .Psyohol . 2§, 194-200 (1964) . 15 . L.W . HAMILTON, R.A . Mo CLEARY and S .P . GROSSMAN, J Com . Rhysiol . Ps oh
. 66, 563-568 (1968) .
16 . P . KARLI, ~. Ph3"siol . (Paris) , 60 Suppl. 1, 3-148 (1968) . 17 . D.P . KIMBLE and R.J . KD03LE, J .oomP .p bjvsiol .Psyohol . 6Q, 474-"476 (1965) . 18 . K. KRNJEVIC and A . SILVER, J . Anat . 100, 63-89 (19667 . 19 . P .R . LEWIS, C .C .D . SHIITE and A . SILVER, J . P
si
. 1.21,
215-224 (1967) . 20 . P .R . LEWIS and C .C .D . SHIITE, Brain. 20, 521-540 (1967) . 21 . L. LUBINSKA, S . NIEMIERKO, B . ODERFELD and L. SZWARC, J.Neuroohem . 10, 25-41
(1963) .
22 . J.S . MATHISEN and T .W . BLACKSTAD, Aota anat . ~j, 216-253 (1964) . 23 . R.A . Mo CLEARY, Progress in Physiologioal psychology , Academio Press, New York, (1966) . 24 . E .G . MoGEER, J .A . WADA, A . TERGO and E . JUNG, ExDtl . Neurol . 227-284 (1969) . 25 . L. NITECSA, 0. NARKIEWICZ and H. ZAWISTOWSKA, Aota Neurobiol. =. 31 , 383-388 (1971) . 26 . H. PETSCHE, C . STUMPF and G . GOGOLAK, Eleotroenoephal .olin. Neurophysiol . 14, 202-211 (1962) . 27 . G . RAISMAN, W .M . COWAN and T.P .S . POWELL, Brain . U, 83-108 (1966) . 28 . B .H . TURNER, J . oomp .physiol .Psychol . 7, 103-113 (1970) .