Ne~os¢/e~ Let~er~, 15 (19 ~ , 6 1 ~ E~e~fNor~h-Hoiland S ~ - ~ P u b ~ h ~ L*~.
AFFERENT C O N N F ~ O N S NUCLEUS ~N M ~ T
OF M
LATERODORSAL ~AMIC
Depar~ent of Neuro~,ator~. Iemtitste of Zoology. J~eUon~en U n i ~ i t y . 30.060 K ~ ~Po~nd~ (RecededM~y 2~h, 1979) ( ~ v~cm ~ed July 30th, 1979) (Accepted Juiy 3let: 1979)
Sb2~[MARY
The la~erodo~al ~ c affe~nt connectio~ have been studied by m e ~ of ~ e reizogr~e mms~rt, of horse~di~ pe~idase (HRP). The following new s o ~ of pm'~ctions ~ the later~lo~ t ~ nucleus (LD) were obserced: the zona ~ncerta,~ ~ dorsal tegmental nucleus (bilaterally),the l~tezalhypothalamus and the precentralagranul~r cortex.
On the bmfls ~f the degeneration and autorm~og~phic m e t h ~ the laterodonml thalamic nuc~tts (LD) is known to r e c ~ e afferents ~om the iimv~c cortez [3,9,10,11,13,18,20--~2], the pexietel cortex [2,6,!.2,
i ,17] and
p ecbxm [81.
The ptupoee of this paper we~ to obta~ a w ~ e detailed pictu~ of afterent con,*mctions of ~ia nucle~ ~ ~ ~ P method (Fi~ 1). Eight ra~ were unilaterally injected with 10 ~l Hamilton ~ ~ e 0.i ~l o: 50% HRP ( ~ x i n ~ e ~ ) under H ~ o ~ ~ e ~ into LD. ~II L~3ect;ons w~e confined to its entire extent (Fig. 2). Following a 48-h suro v~val period, the animals were 9erfused t~ough the aorta with 0.9% saline followed by a 0.5% fommldehyde and 1.25% glutaraldehyde mixture in pb~~ btflTer (pH 7.4). The ~ were removed emil po~flxed in the uuue wok~tlon for several hourw, l~ozen frontal sections were cut at 40 ~m thicknem, p r ~ sceordtng to the me~od of Graham and Ka~ovsky [ 5], ~ y m o t m ~ and e o t m t ~ e d with 0.5% ¢ ' - ~ I violet. Every ~th ~ w u mi~meop~elly effi~ned ~ both conventional ~nd -
-
t h e r a t w e r e idenrecen~ ~rant~r
e~y fo~
in the
~2
+
Fig, I. :~tribution of label~i cell~ h~ representative~ ~ e ,~irat's~ following H R P in~tion into L D thakmL Dot~ indic,,tethe location cf ~ffY~F-matked ce~. The blackened area indicatesthe inje~¢ionsite,dot~ ~ diffus~ou. Abbrevhflone: ~t~,
areap r e ~
medhlk; HI,,h y p o t ~ ~
latemlk;LD, n u ~
~tz~dotmlk ~ ;
NP) nucleus p r e t t Y ; NTD, llttele~ ~ t t d ~ ~i~ FAG, ~ ~ pre~nt~l~ agran~i~; PAR, cortex pa~ietelis; PS, ~ i e u l ~ _ ~ , ; RA, c ~ re~o~~ ~nul~ri~: 8, subiculum; ZI, zorm ~neerta,
zona incerta(Fig.ID). and only few in the l a ~ h ~ c t ~ m u s eft. IC and 8). There were ~ | e d pyr~Jclal n ~ ~ s c a t ~ in th~ p r ~ ~ ag~u~r coz~ex in layersIII--VI( ~ . 1A,B,C) ~th the m~jo,Atym the d ~ t ones. This area isknown ~ receiveD r O ~ ~ S from ~ [1]. O ~ ~ l t ~ indica~ the ~ n c e of r e c i p ~ p~je~ions. In the me senceph~on, hbeled ~ were b ~ y ~ ~ in the l a ~ do~s~ ~ ~ n t a l nucle*.m(Fig.IH)o Out ~ , ~ t s c o n ~ and ~ e more ~ t a ~ e d infozmati~ c o n c ~ g project;'gns to LD which ~ ~ ~ y ~b~~: ~ o m ~ retr~ the s u b ~ l u m {21 ],~ e p m t e c ~ m [8 |,~ ~ cortex [2)6,1~!6,17] H R P c¢~l~ ~ m e n t in ~ e retro~ial ~ ~ cortex ~ the as o ~ e d m ~ e p r e c e ~ ~pmnuL~r cortex. Few ~P.po~'tive ceth of ~ e s~x~ layer were p ~ t m ~e retrosp~ ~ ~ c ~ (fig. 1E,F,G) ~ ~ o w its b o u ~ ~ ~th the retzosple~ ~ u l ~ - corte~. H R P - ~ t i v e c ~ were o ~ ~ i n ~ de~ l~yers of the ~ i h t e ~ prembieulum (Fig.IG) as well as the ipsila~ s u b ~ ~ / C ~ 1 ( ~ . IF,G). In ou~ ~ P s t u ~ m ~ e ~ ~ ~ w e ~ pzesevt m t h . m ~ l
~a~ ~
~ge p
""oal n e u r o n s
f th
63
Fig. 2. Light f'mld photomicrograph of the i~eetion ~ite in LD. Crecy| viole~ eounCergain. z 5 Fig. 3. !)turkfield photomicrograph of labeled cells in *~helateral hypothalmnus. × 120.
layer of the . ~ i e l a l cortex neighbouring the agranular part of the c i n ~ a t e cortex project to LD (Fig. 1C,D,E). With the HRP methocl we indicated d e connection from the precentr~l ~uiax c,~(~x to LD, which was not visualized in the degeneratio~ studies [ 3,4] because of d i s p e ~ arrangement and small cell number. It is known [ 3,4] that the cin.gulaCe cortex pro~evts to the zona m c e r ~ whereas only its posterior p ~ , i.e. the ~e~ospleni~ ~gmnular cortex, projec~ to LD. To conclude, LD ~ e ~ e u di~e~ and i n d i ~ c t projection~ from the cingulate co~,ex, the i.~~*~r via the zona iz~certa. ~e pre~e oi" HRP-poai~vc neuron~ i~ the la~ral h y p o t h ~ a m u s and the ]at~ra| ~:|or~ ~ e n ~ nucleu~ demon~txa~ the e~i~.e.nce of addi~ o ~ ~mbic affe~ent~. Remaining LD af~ren~g origina~ in ~he subcorticai v~u~l center i.e. ~ e t e c t u m | 8], ~ e parietal a ~ c i a ~ i o n c o r ¢ ~ [ 2,6, 12,16,17] a~d the limbic cortex [3,9,10,11,13,18,29--22]. Taking i:nt~) consideration the dominance of limbic projectiorm a m o ~ ,Ai LD ~ f e ~ t a , it may be i~o~tu!~.*~d gnat LD play~ a special role in integrating ILmbic furor:ions f~om dLfferent l ~ e ~ of/~he brain. A~iOWLEDGEMI!~N'r~ The a n t h o ~ w o ~ ~ilke to thank ~ s . A~ KurLzek and Mi~ M. M ~ z a l e k for the~ e x e r t techrdca! ~asi~.~ce. REFERENC~ i ~.~c~te~, ~.M°, Convergent tha~mic ar~ me~cep~mlic pro}ec~ic~ ~ ~he a ~ ~
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Angevine, J.B., Jr., The i t n ~
of the ee~elmd h ~