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The conduction velocity in retino geniculate afferent fibers in the rabbit
Neuroscience Letfern, 16 (1980) 175-179 0 Elsevier/Nsrth-Holnd Scientific Publishmu Ltd.
:71i
‘ME CONDUClTON VELOCITY M RETJNO GENICULATE AFFERENT FIBERS IN THE RABBIT
J.H. REIJTZF: and K.-P. HOFFMAN Dept. of Neurobiology, Uniwnity of Vim (F.R.G.) and Dept. of Phystology, Faculty. Uniwnity of Rottemlom (The Nether/an&i
Mcdicul
(lieeeived October 10th. 1979) (Reviacd remim received Novmnber 16th, 1979) (Accepted November 19th, 1979)
SUMMARY
We have recorded .?I- and Y-like cells in the rabbit !ateral geniculated nucleus (LGN) and found a small but statiitically significant difference between the latencies of the two cell types to stimulation of the chiaso. The relative frequency o.f recordable Yells was equal in pigmented and i~i aIbintr rabbits. 1% relative increase in the recording probabiiity of Ycells versus X-cells was found with increasing eccentricity of the receptive field (RF) locations with respect to the visual streak in either breed. .In the cat, rat, monkey and rabbit t.he retinal gru:glionceug (and the ce!ls in the lateral geniculate nucleus, LGN) have been clxssified in a number of types according to their receptive field (RF) properties and their conduction v&cities (cv). The RF that have a centef+mrround field organisation contain the X- and Yqells [4], it has been shown that in the cat the X-cell axonn have a lower cv t& the Y-cell axcns [S]. Moreover it has been found in the LGN of the cat that the re!ative number of recorded Y-cells increases with increasing eccentricity of the RF lo&ion [ 61. Recently it has been shown that the number of recordable Y-cells in the r&ma of Siamese cats is smaller than that in norms1 cats [3]. But in this study no cv was measured. ‘Inpigmented rabbiti the retinal ga@ion cells can be classified in Y- and X-like cells by the srune criteria 80 have been used in the cat [Z]. Here ihe cv was measured and i:xmd on the average to be the same for both cell types. The same resulb~ were obtained wit,b stimulaticn of the colliculus superior [9,10]. It was
Correspondwux: Ijr. J.H. R.mtm,Dept.of mm Netberland.¶.
Physiology,hfedical
Faculty, Univ., Rotterdam,
176 argued [Z ] that thin lack of difference could be caused hy the difference in
myelini&ion of the nffercnt fibers in the retina. fn the present study ~4: wanted to test two questions. Is there a correlation between latency and RF properties in the L4ZN despite the retinal findings because cv groups exist in the optic pathway [ 1,6,9], and are there differences of X- and YuAl frequencies in albino and pigmented rabbits? Uniti. were recorded in Dutch Belted (pigmented) and New Zealand White
(albino) :dult rabbi& Recording and preparation were done with conventional tixhniques under urethane anaesthesia (1600 mg/kg). LGN and chiasm were reached siereotactically from above, and positioning of the stimulating electrodes in the chiasm (OX) was done while recording the field potential in the visual cortex. After the start of the Piax~dil@ administration the endby regulation of the expiratory pCOl was monitored and held at X5-4.096 stroke volume. The body temperature was kept at 37-37.5% by a thermistor regulated electric heating blanket. The :mpils ‘were dilated with atropine and the corneas protected by clear 0 diopter cont& lenses. Tun&en in glass and varnished kungsten microelectrodes we1.eIII-& for recording (:!-7 MOhm, 5 mV at 1000 Hz). After isolation of a unit in the LGN, the RF was plotted with hand held visual stimuli. Classification of the unit as a Y- or X-cell follo*wed the criteria as previously used in the cat: large surround stiialating field stimuli moved at a v&able speed through the RF, movement of a grid with a variable spatial iiequency through the RF [6,7], and the transient or sustained response to static stimuli. These criteria. have been shown to be of equal value in the rabbit [ 2 J . In a number of experiments lesions were maJe at several locations during the recording. The animals were prepared for histology by perfusion with 4% formaldehyde and the sections were stained with Kliiver-Barers and Nissl stains.
We recorded the response of 129 LGN cells in 8 pigmented and 10 albino animals. Table I shows the breakdown of the data. No difference is found between the incidences of X- and Y-cell recording in the albino and pigmented rabbits (x1-t&: P > 0.2). Thus, contrary to the findings !a the cat 131, in the rabbit no reduction in the recordability of the Y4ls in the albino compared to that in the pigmented animals was found. Moreover when tomparing the latency distributions of the recorded ccl16 in the two rabbit breeds no difference WESfound for either that of the X.cell3 or that of the Yce!ls
(U-test: P > 0.1). Furthermom we compared the 6!.:t’ribntion of the RFs of the X- and Y-cells in the visual field. On the basis oi’our, admittedly small, sample of neurons recorded, neither in the albino nor in the pigmented animals a change in relative occurrence of Y-RFs with different eccentricities (as was found in the cat, ref. 5) was seen. As the 3 parameters mentioned above showed no difference in our experime& i:he results for these were pooled in the following. Figure 1 shows that the disidbutions of the latencies of both types of c&ls overlap extensively
X x X Y Y Y
0:
(on) (off)
(on) (off)
Type
cdl
16 23 41 19 16 35
11 16 27 9 17 26
pigm.
of unit.4
&bin.
No.
24 30 54 25 “1 46
ahii.
90 oi
unit6
21 30 51 17 32 49
22 36 52 22 26 46
pigrr;. tstal 2.5 2.2 2.3 1.9 1.8 1.8
(O.a’s) (0.64) (0.76) (0.30) (0.23) (0.29)
albino
2.1 (0.62) 1.9 (0.67) 2.0 (0.62) 2.1(0.63) 1.9 (0.28) 2.0 (0.74)
pigmented
-.
1.9 (0.54)
2.2 (0.74)
total
Latency to OX stimul. + S.D.
NUMBER OF CELLS RECORDED AND MEAN LATENCY TO CX STIMULATION PER CLASS OF CELLS
TABLE i
178
with previous findjn@ [2,8 ] but staktical evaluation of the means of the 2 populationn showed the Y-cek to be signifirantly faster (Uteet: f < 0.005). This sranll but eignifksnt difference in the mean latency Lo (IX stimulation oi X- :md Ysell~ in the LGN of the rsbbit, indicates a slightly fa8l;es cv for the Yu9l11. This ad difference in cv c,annot explain the larger diiferenze between the two peaks in the field potential recorded by others f 1,631. Figure 2 presents the distribution of EJIthe recorded i?Ps in the viauai 5eId.
in accordance
Fig. 2. Location in tlw tidal field of the RF recxded msb. Thr double circle meana 2 Y-c& rmrdec .
in the albino and pigmented ani-
In cat81the relative aumber of Y-U& recorded in the LGn increases with increaning dbtance of the Rf&ea from the area centralis. Ne;ther the HFr recorded in the albino nor thone recorded in the pigmented rnhbiti or thlse in the combined results rhowed a clear increase of the re:ativo number of Y. cellsrsxorded wi+h increasing dirrtancx from the visual streak. Figure 2 rihows that the fleatest number of RT recorded were located in thz visual rtreak. bur renultn nuggest that the PibIity mentioned by C~ldwcll and IJaw [ X] that a posaihle difference in X- and Y-cell cv wan masked in their recordings by the _pmsihledifference in myelinisntion of the afferent fibem in the eye is only pa&j- born out. ACKNOILEDGEMENTS J.H.R. received a grant frr;m t.he NcC,heniandnOrg~~lixation for the Atlvar~c~:., ment of Pure Research (Z.W.O.), the l-lay{:; 1::I’.lf. rawivc*l :i IiN grant r)r, fro 450/7. The authorn are indebted to Prof. IJr, M.W. van ffof for his encouragemeat, to Mr. Jack V.‘~~xeifor his help with part of the ewperirner.ts and to Mrs. d. Adamova for ;idp with the iGrtology. I:EFERENCEB 1 Bihup, G.H., Fiber gzoupl in the optic nerve, Amer. J. Phyliol.. 106 (13%~) ,,M-474. 2 CaldrclI, J.H. and hn, N.W., New poprties or rat hit retinrl ganglion cellr, d. Pbyaiol. (Lond.J, 276 (1876) 267-276. 3 Chino, Y.M., Wmnrky, MB and Hamuaki, D.J., r’rop~rtier of %- and Y.type mtinrl ganglion celh in e&new a*, Brain Rg., 143 (19’M) 459-473. 4 Emotb-Cugell, C. and Gibson, J.G., ‘Ihe contradt remitivity of rctinnl ganglion cell:: in the at, J. F’hymiol. (Lund.), 197 (1966) 517~S52. 5 Hoffmmn, K.-P., Rtone, 5.. ar.3 Sherman, S.M..Relay of receptive field prop&i+&in dotul lateral genicuiak nucleus of lhe cut, J. Neurop!ysiol., 35 (39723 SlH-531. 6 Ledennan, RI. and NoelI, W.K., Pad-fiber nyatem of rthhit optic: nerve, VimiQn Her., 6 (lB66) 1665-1398. I &at& K.E., Webb, 6.V. and 6bennan,9_M., Elw tropllysiologi-A claui’lr.Ltion CJIIiand Y-ul;b in the afal~~teml6aAMe nucleu, Vhicn Rea., 16 (1976) 126l-1264. a Rodi~~k, R.W., Viiwl pathways, Ann. Rev. Neurud., ? (1972) 183-226. a&+&d direction wlectin! pirqlion c&s of (he rabbit, 9 &mm, P.; Antidromtiy Neurad. L&t., 9 (1976) 207-211. 2.0 Vmey, DJ., 8tudIea on the rbual syrtem of the vahbi :, I%#!&, A&ml. Sat LX/., hru~aalia. lB7B.
:71i
‘ME CONDUClTON VELOCITY M RETJNO GENICULATE AFFERENT FIBERS IN THE RABBIT
J.H. REIJTZF: and K.-P. HOFFMAN Dept. of Neurobiology, Uniwnity of Vim (F.R.G.) and Dept. of Phystology, Faculty. Uniwnity of Rottemlom (The Nether/an&i
Mcdicul
(lieeeived October 10th. 1979) (Reviacd remim received Novmnber 16th, 1979) (Accepted November 19th, 1979)
SUMMARY
We have recorded .?I- and Y-like cells in the rabbit !ateral geniculated nucleus (LGN) and found a small but statiitically significant difference between the latencies of the two cell types to stimulation of the chiaso. The relative frequency o.f recordable Yells was equal in pigmented and i~i aIbintr rabbits. 1% relative increase in the recording probabiiity of Ycells versus X-cells was found with increasing eccentricity of the receptive field (RF) locations with respect to the visual streak in either breed. .In the cat, rat, monkey and rabbit t.he retinal gru:glionceug (and the ce!ls in the lateral geniculate nucleus, LGN) have been clxssified in a number of types according to their receptive field (RF) properties and their conduction v&cities (cv). The RF that have a centef+mrround field organisation contain the X- and Yqells [4], it has been shown that in the cat the X-cell axonn have a lower cv t& the Y-cell axcns [S]. Moreover it has been found in the LGN of the cat that the re!ative number of recorded Y-cells increases with increasing eccentricity of the RF lo&ion [ 61. Recently it has been shown that the number of recordable Y-cells in the r&ma of Siamese cats is smaller than that in norms1 cats [3]. But in this study no cv was measured. ‘Inpigmented rabbiti the retinal ga@ion cells can be classified in Y- and X-like cells by the srune criteria 80 have been used in the cat [Z]. Here ihe cv was measured and i:xmd on the average to be the same for both cell types. The same resulb~ were obtained wit,b stimulaticn of the colliculus superior [9,10]. It was
Correspondwux: Ijr. J.H. R.mtm,Dept.of mm Netberland.¶.
Physiology,hfedical
Faculty, Univ., Rotterdam,
176 argued [Z ] that thin lack of difference could be caused hy the difference in
myelini&ion of the nffercnt fibers in the retina. fn the present study ~4: wanted to test two questions. Is there a correlation between latency and RF properties in the L4ZN despite the retinal findings because cv groups exist in the optic pathway [ 1,6,9], and are there differences of X- and YuAl frequencies in albino and pigmented rabbits? Uniti. were recorded in Dutch Belted (pigmented) and New Zealand White
(albino) :dult rabbi& Recording and preparation were done with conventional tixhniques under urethane anaesthesia (1600 mg/kg). LGN and chiasm were reached siereotactically from above, and positioning of the stimulating electrodes in the chiasm (OX) was done while recording the field potential in the visual cortex. After the start of the Piax~dil@ administration the endby regulation of the expiratory pCOl was monitored and held at X5-4.096 stroke volume. The body temperature was kept at 37-37.5% by a thermistor regulated electric heating blanket. The :mpils ‘were dilated with atropine and the corneas protected by clear 0 diopter cont& lenses. Tun&en in glass and varnished kungsten microelectrodes we1.eIII-& for recording (:!-7 MOhm, 5 mV at 1000 Hz). After isolation of a unit in the LGN, the RF was plotted with hand held visual stimuli. Classification of the unit as a Y- or X-cell follo*wed the criteria as previously used in the cat: large surround stiialating field stimuli moved at a v&able speed through the RF, movement of a grid with a variable spatial iiequency through the RF [6,7], and the transient or sustained response to static stimuli. These criteria. have been shown to be of equal value in the rabbit [ 2 J . In a number of experiments lesions were maJe at several locations during the recording. The animals were prepared for histology by perfusion with 4% formaldehyde and the sections were stained with Kliiver-Barers and Nissl stains.
We recorded the response of 129 LGN cells in 8 pigmented and 10 albino animals. Table I shows the breakdown of the data. No difference is found between the incidences of X- and Y-cell recording in the albino and pigmented rabbits (x1-t&: P > 0.2). Thus, contrary to the findings !a the cat 131, in the rabbit no reduction in the recordability of the Y4ls in the albino compared to that in the pigmented animals was found. Moreover when tomparing the latency distributions of the recorded ccl16 in the two rabbit breeds no difference WESfound for either that of the X.cell3 or that of the Yce!ls
(U-test: P > 0.1). Furthermom we compared the 6!.:t’ribntion of the RFs of the X- and Y-cells in the visual field. On the basis oi’our, admittedly small, sample of neurons recorded, neither in the albino nor in the pigmented animals a change in relative occurrence of Y-RFs with different eccentricities (as was found in the cat, ref. 5) was seen. As the 3 parameters mentioned above showed no difference in our experime& i:he results for these were pooled in the following. Figure 1 shows that the disidbutions of the latencies of both types of c&ls overlap extensively
X x X Y Y Y
0:
(on) (off)
(on) (off)
Type
cdl
16 23 41 19 16 35
11 16 27 9 17 26
pigm.
of unit.4
&bin.
No.
24 30 54 25 “1 46
ahii.
90 oi
unit6
21 30 51 17 32 49
22 36 52 22 26 46
pigrr;. tstal 2.5 2.2 2.3 1.9 1.8 1.8
(O.a’s) (0.64) (0.76) (0.30) (0.23) (0.29)
albino
2.1 (0.62) 1.9 (0.67) 2.0 (0.62) 2.1(0.63) 1.9 (0.28) 2.0 (0.74)
pigmented
-.
1.9 (0.54)
2.2 (0.74)
total
Latency to OX stimul. + S.D.
NUMBER OF CELLS RECORDED AND MEAN LATENCY TO CX STIMULATION PER CLASS OF CELLS
TABLE i
178
with previous findjn@ [2,8 ] but staktical evaluation of the means of the 2 populationn showed the Y-cek to be signifirantly faster (Uteet: f < 0.005). This sranll but eignifksnt difference in the mean latency Lo (IX stimulation oi X- :md Ysell~ in the LGN of the rsbbit, indicates a slightly fa8l;es cv for the Yu9l11. This ad difference in cv c,annot explain the larger diiferenze between the two peaks in the field potential recorded by others f 1,631. Figure 2 presents the distribution of EJIthe recorded i?Ps in the viauai 5eId.
in accordance
Fig. 2. Location in tlw tidal field of the RF recxded msb. Thr double circle meana 2 Y-c& rmrdec .
in the albino and pigmented ani-
In cat81the relative aumber of Y-U& recorded in the LGn increases with increaning dbtance of the Rf&ea from the area centralis. Ne;ther the HFr recorded in the albino nor thone recorded in the pigmented rnhbiti or thlse in the combined results rhowed a clear increase of the re:ativo number of Y. cellsrsxorded wi+h increasing dirrtancx from the visual streak. Figure 2 rihows that the fleatest number of RT recorded were located in thz visual rtreak. bur renultn nuggest that the PibIity mentioned by C~ldwcll and IJaw [ X] that a posaihle difference in X- and Y-cell cv wan masked in their recordings by the _pmsihledifference in myelinisntion of the afferent fibem in the eye is only pa&j- born out. ACKNOILEDGEMENTS J.H.R. received a grant frr;m t.he NcC,heniandnOrg~~lixation for the Atlvar~c~:., ment of Pure Research (Z.W.O.), the l-lay{:; 1::I’.lf. rawivc*l :i IiN grant r)r, fro 450/7. The authorn are indebted to Prof. IJr, M.W. van ffof for his encouragemeat, to Mr. Jack V.‘~~xeifor his help with part of the ewperirner.ts and to Mrs. d. Adamova for ;idp with the iGrtology. I:EFERENCEB 1 Bihup, G.H., Fiber gzoupl in the optic nerve, Amer. J. Phyliol.. 106 (13%~) ,,M-474. 2 CaldrclI, J.H. and hn, N.W., New poprties or rat hit retinrl ganglion cellr, d. Pbyaiol. (Lond.J, 276 (1876) 267-276. 3 Chino, Y.M., Wmnrky, MB and Hamuaki, D.J., r’rop~rtier of %- and Y.type mtinrl ganglion celh in e&new a*, Brain Rg., 143 (19’M) 459-473. 4 Emotb-Cugell, C. and Gibson, J.G., ‘Ihe contradt remitivity of rctinnl ganglion cell:: in the at, J. F’hymiol. (Lund.), 197 (1966) 517~S52. 5 Hoffmmn, K.-P., Rtone, 5.. ar.3 Sherman, S.M..Relay of receptive field prop&i+&in dotul lateral genicuiak nucleus of lhe cut, J. Neurop!ysiol., 35 (39723 SlH-531. 6 Ledennan, RI. and NoelI, W.K., Pad-fiber nyatem of rthhit optic: nerve, VimiQn Her., 6 (lB66) 1665-1398. I &at& K.E., Webb, 6.V. and 6bennan,9_M., Elw tropllysiologi-A claui’lr.Ltion CJIIiand Y-ul;b in the afal~~teml6aAMe nucleu, Vhicn Rea., 16 (1976) 126l-1264. a Rodi~~k, R.W., Viiwl pathways, Ann. Rev. Neurud., ? (1972) 183-226. a&+&d direction wlectin! pirqlion c&s of (he rabbit, 9 &mm, P.; Antidromtiy Neurad. L&t., 9 (1976) 207-211. 2.0 Vmey, DJ., 8tudIea on the rbual syrtem of the vahbi :, I%#!&, A&ml. Sat LX/., hru~aalia. lB7B.