Experimental Brain Research
Exp. Brain Res. 34, 551-574 (1979)
9
Springer-Verlag 1979
Learning and Interhemispheric Transfer of Visual Pattern Discriminations Following Unilateral Suprasylvian Lesions in Split-chiasm Cats G. Berlucchi 1, J.M. Sprague;, A. Antonini 1, and A. Simoni 1 1 Istituto di FisioIogia dell'Universit/t di Pisa and Laboratorio di Neurofisiologia del CNR, Via San Zeno 31, 1-56100 Pisa, Italy 2 Department of Anatomy, Medical School, and Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA, USA
Summary. A suprasylvian lesion removing cortical areas 7 and 21 and portions of area 19 and of the lateral suprasylvian area was placed in one hemisphere of split-chiasm cats. By comparison with the normal side and with cortically intact split-chiasm and split-brain cats, form discrimination learning with the eye on the injured side was severely retarded. This deficit could not be attributed to an unintentional undercutting of areas 17 and 18, since in three cases the laminae of the lateral geniculate nucleus showed little retrograde atrophy; marked degeneration was found in the medial interlaminar nucleus and the pulvinar complex. In addition, interocular transfer of form discriminations to the eye on the injured side was absent or poor, while transfer in the opposite direction was normal. A cat with a suprasylvian lesion undercutting areas 17 and 18 was unable to learn pattern discriminations with the eye on the injured side, in spite of prolonged training with that eye and normal learning with the other eye. Another cat with a suprasylvian lesion selectively removing the anteromedial and posteromedial portions of the lateral suprasylvian area showed no learning deficit on the injured side, but p o o r transfer to that side. A learning deficit on the side of the lesion emerged in this cat after forebrain commissurotomy. The results support the hypothesis of a major involvement of cortical areas outside of 17 and 18 in the processes of abstraction and generalization of visual information necessary for learning and interhemispheric transfer of form discrimination in the cat. Key words: Split-chiasm cats - Cortical lesions - Form Discrimination Visual learning - Interocular and interhemispheric transfer
Offprint requests to. Dr. G. Berlucchi (address see above)
0 0 1 4 - 4 8 1 9 / 7 9 / 0 0 3 4 / 0 5 5 1 / $ 4.80
552
G. Berlucchiet al.
We have recently reported that split-chiasm cats retain their capacity for interocular transfer of form discriminations following unilateral or bilateral lesions of the visual cortical areas 17, 18, and 19 (Berlucchi et al., 1978b). Since section of the main cortical commissure, the corpus callosum, abolishes interocular transfer of pattern discriminations in split-chiasm cats (Myers, 1956; Sperry et al., 1956), it follows that cortical areas other than 17, 18, and 19 are sufficient for ensuring the interhemispheric exchange of visual information required for interocular transfer following splitting of the optic chiasm. In the present experiment we have tested the effects of unilateral lesions of the middle and posterior suprasylvian gyri on interocular transfer of form discriminations in split-chiasm cats. In addition to an important portion of area 19, the middle and posterior suprasylvian gyri contain a number of cortical areas (Otsuka and Hassler, 1962; Sanides and Hoffmann, 1969; Heath and Jones, 1971; Palmer et al., 1977; Sprague et al., 1977; Tusa, 1978) which receive visual information from the lateral geniculate nucleus ( L G N d ) and/or from parts of the pulvinar nuclei which in turn are innervated by projections from the superior colliculus and pretectum (Altman and Carpenter, 1961; Niimi et al., 1970; Graybiel, 1972a, 1972b; Rosenquist et al., 1974; Itoh, 1977; Graham, 1977; Berman, 1977). These areas are also supplied with reciprocal callosal connections with the eontralateral hemisphere, and these connections do not appear to be limited to the representations of the vertical meridian of the visual field (Heath and Jones, 1970, 1971), in clear contrast to the organization of the callosal connections of area 17, 18, and 19 (Berlucchi, 1972). The importance of suprasylvian areas for visual discrimination in the cat has recently been indicated by a number of studies (Hara et al., 1974; Wood et al., 1974; Alder and Meikle, 1975; Cornwell et al., 1976; Sprague et al., 1977; Baumann and Spear, 1977). These same areas have been shown to contain neurons with large receptive fields, often extending across the vertical meridian of the visual field (Hubel and Wiesel, 1969; Wright, 1969; Dow and Dubner, 1971; Spear and Baumann, 1975; Turlejski and Michalski, 1975; Camarda and Rizzolatti, 1976; Palmer et al., 1977). A study of the neural basis of interocular and interhemispheric transfer of visual learning in the monkey has emphasized the critical importance of neurons with similar receptive fields (Gross and Mishkin, 1977), thus suggesting an analogous role for the neurons in the suprasylvian areas of the cat. The present study shows that both learning and interhemispheric transfer do indeed suffer from removal of these areas.
Methods Surgery and Histology
All surgical procedureswere carried out in 7 cats under Nembutal anesthesia (35-40 mg/kg, i.p.). The optic chiasm was sectioned as described by Myers (1955) and the forebrain commissureswere sectioned as describedby Berlucchi(1966), Sperry (1968) and Trevarthen (1972) after retraction of the hemisphere contralateral to a cortical lesion. Cortical lesions were made by subpial aspiration. Histological preparation and analysis were the same as described by Sprague et al. (1977). Cortical lesions were reconstructed both by examinationof coronal sections and by evaluation of the
Learning and Interhemispheric Transfer of Visual Pattern Discriminations
553
l+rl Fig. 1. Pairs of forms used in discrimination training. In each pair the two black forms have equal area. Size of stimuli in the figure is reduced to about 1/20 of that of the stimuli used in the discrimination box. Positive stimulus is on the left except for Problem 1
+l,.e~
L xl
retrograde atrophy in the thalamus. Designation of cortical areas is taken from the work of Tusa et al. (1975), Palmer et al. (1977), and Tusa (1978) and is illustrated by Sprague et al. (1977) and Berlucchi et al. (1978b).
Training Apparatus, Testing Proceduresand Experimental Design The training apparatus has been described in detail elsewhere (Berlucchi and Marzi, 1970; Berlucchi et al., 1972; Berlucchi et al., 1978a, 1978b). Briefly, the discriminanda were presented on two side-by-side top-hinged doors illuminated from behind. In order to obtain a reward consisting of a sinai1 piece of beef kidney, the cat, which had been food-deprived for about 24 h, had to push open the door displaying the positive stimulus. The other door was locked. After an error which consisted in pushing the locked door, correction was allowed. Following the attainment of the reward the animal was replaced in the start-box and the next trial began immediately. A daily session consisted of 40 trials, 20 of which were run with the positive stimulus on the right door and 20 with the positive stimulus on the left door. The two stimulus conditions were alternated in a quasi-random order according to a modified Gellermann (1933) sequence. All animals were first trained binocularly on a simple light-dark discrimination, that is with only one door lighted with no patterned stimulus on it (mean luminance 39 cdm-Z), until they reached a learning criterion of two consecutive sessions with no more than four errors in each session. The dark door (mean luminance 0.3 cdm -2) was chosen as the positive stimulus. Following attainment of the learning criterion, each eye was tested separately by covering the other eye with a black plastic occluder. Monocular testing continued until the animal reached the same learning criterion. This procedure served to familiarize the animals with the training apparatus and the monocular testing. The optic chiasm was sectioned in all cats following the above procedure. After a recovery period of at least two weeks, each cat was retrained first binocularly and then monoeularly with the same light-dark discrimination. Subsequently a cortical lesion was placed in one hemisphere of each cat. After a recovery period of at least two weeks, there was a second retesting, both binocular and monocular with each eye, on the light-dark discrimination. This was followed by monocular training and tests of interocular transfer on various pattern discriminations shown in Fig. 1 (numbered 1 to 7). The basic paradigm involved training with one eye until reaching the criterion of two consecutive sessions with at least 90% correct responses, followed by overtraining with the same eye for 5 regular sessions. The eye used for learning was then occluded and the other eye was trained to the same criterion. However, as specified later, two cats (C 50 and C 56) failed to reach above-chance levels of performance when using the eye on the injured side in spite of prolonged training. In each cat, the eye order was reversed from problem to problem, so that the eye on the intact side was used for learning some problems and the eye on the injured side was used for learning other problems. Cats C 47, C 50, and C 52 were tested on 4 pattern discriminations, C 45 on 2, C 53 on 6, C 56 on 3, and Sub 4 on 5, as specified in Table 1. Counterbalancing across cats was used for equafizing the difficulty I of the discriminations learned by intact and injured side, respectively, but such a counterbalancing could 1 The relative difficulty of the discriminations was assessed on the basis of the mean number of errors committed by control split-chiasm and split-brain cats before attaining the criterion of learning of each discrimination (see below)
554
G. Berlucchi et al.
Table 1. Sequence of problems (numbered as in Fig. 1) and eye used for learning in each cat Cat
Problem
Eye used for learning
C 45 lesion on left side
2 3
L R
C 47 lesion on left side
2 4 3 5
R L R L
C50 lesion on right side
8 4 3 5
L R L R
C 52 lesion on right side
2 4 3 5
R L R L
C53 lesion on right side
2 4 3 5 1 6
L R L R L R
C56 lesion on left side
2 4 3
L R R
Sub 4 lesion on left side
3 5 1 6 7
L R L R R
not be perfect because of differences in the number of problems learned by the different cats. Accordingly, further corrections were introduced in the analysis of the results, as indicated in the Results section. After completion of testing on pattern discriminations, the forebrain commissures were completely sectioned in cats C 45, C 47, and Sub 4. These cats were then retested monocularly with each eye on the discriminations learned before commissurotomy, by alternating eyes from session to session. C 45 was then trained with either eye on alternate days on three new discriminations. Cat C 53 was submitted to a suprasylvian lesion in the previously intact hemisphere and tested for retention in the same way as the three commissurotomized cats.
Results
Histology A l l c h i a s m a t i c a n d c o m m i s s u r a l s e c t i o n s w e r e c o m p l e t e , as i n t e n d e d . T h e a n a l y s i s o f t h e c o r t i c a l l e s i o n s is s u m m a r i z e d i n T a b l e 2. C a t s C 47, C 52, C 53,
LG-intact
P S S G - xx
and symbols: LG
damage
AMLS
and/or
- xxx
- xxx
- xxx
- xxx
- xxx
PSSG - x
MSSG
P S S G - xx
MSSG
PSSG
MSSG
PSSG - intact
- xxx
xx
MSSG
- xxx -
MSSG
- intact
PSSG
PSSG
MSSG
Intact
21
atrophy, xx = moderate
and/or
- xx
- xxx
- x
PMLS
AMLS
Caudal
1/3 - NIM - xx
C,C1-2 - xx N I M - xx
1/3:A-A1
Intact except Middle
atrophy, xxx = severe damage
and/or
atrophy
= ant. lat. suprasylv_ area, PLLS
xxx
-
Mid. = dorsal suprasylv, area,
18), MSSG
P.lat.v - xxx
P.inf.
P.lat.v - xxx
PAnE - xx
P . l a t . d -- x
caudal pole
P.lat.v - xxx exc.
= post. lat. suprasylv, area, x = minimal
= ventral syprasylv, area, DLS
half xxx
PAnE - x - xx
P.lat.v - xxx
P.inf.dorsal
P . m e d . ~ _ a - xx
P,lat.v - xxx P.lat.a - xxx
P.inf. - xxx
P . l a t . v - xx - xxx
P.inf. - xxx
P. inf. - xx
Pulvinar
vis. f i e l d , 17 +
medial half xxx
1 / 3 : N I M - xx C, C1-~ - x
A1 - x
Caudal
C,Cl-2-xxx medial tips - xxx
Intact except
A+AI
tips xxx
1/3: NIM-xxx;C,Cl_2-x
1/3: intact
medial
Post. 1/3: NIM-xx;
Middle
Rostral
-
C,C1-2 - xx NIM x
Post 1/3:A+A1
Intact except
E x c . c a u d a l p o l e A + A~
All parts - xxx
vis. f i e l d s 1 9 , 2 1 ) , V L S
= Post.
- xx
- x
Intact except
PMLS
AMLS
Intact except
DLS - xxx
Intact except
P L L S - xx
PMLS
x
1 / 3 : N I M - xx
C,C~_2 -x
A1
middle
Intact except
Intact
LGNd
lat. gyrus (A cent. + upper
- xx
Intact except
DLS+VLS
= post. medial snprasylv, area, ALLS
damage
-
- xxx xxx
P L L S -- x x x
ALLS PMLS
- xxx
xx
PLLS-
AMLS
- xx
PMLS
Intact except
AMLS - xxx PMLS - xxx
Intact except
LSA
18, 19), PLG
xxx
xxx
xxx
xxx
xxx
xxx
Intact
7
= post. suprasylv, gyrus (A cent. + upper
= ant. medial suprasylv, area, PMLS
suprasylv, gyrus (7, 21), PSSG
Intact
xx
Intact
Intact
Intact
Intact
Intact
20
= l a t . g y r u s ( l o w e r vis. f i e l d s , 1 7
1 7 in c a u d a l
s p l . G - xx
LG-intact
PSSG - xxx
Intact except
P L G - xx
LG-intact
PSSG - xxx
P S S G - xx
1 8 in l o w e r
Abbreviations
Sub 4
C 56
xx
LG-intact
xxx
-
Intact except
P L G - xx
(Right
-side)
Intact except
C 53
x
Intact except
PLG
C 52
-
xxx
C 50
PSSG
LG-intact
Intact
C 47
Intact
Intact
19
findings in all cats
C 45
17-18
Table 2. Surmnary of anatomical
5"
-
Exp. Brain Res. 34, 551-574 (1979)
9
Springer-Verlag 1979
Learning and Interhemispheric Transfer of Visual Pattern Discriminations Following Unilateral Suprasylvian Lesions in Split-chiasm Cats G. Berlucchi 1, J.M. Sprague;, A. Antonini 1, and A. Simoni 1 1 Istituto di FisioIogia dell'Universit/t di Pisa and Laboratorio di Neurofisiologia del CNR, Via San Zeno 31, 1-56100 Pisa, Italy 2 Department of Anatomy, Medical School, and Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA, USA
Summary. A suprasylvian lesion removing cortical areas 7 and 21 and portions of area 19 and of the lateral suprasylvian area was placed in one hemisphere of split-chiasm cats. By comparison with the normal side and with cortically intact split-chiasm and split-brain cats, form discrimination learning with the eye on the injured side was severely retarded. This deficit could not be attributed to an unintentional undercutting of areas 17 and 18, since in three cases the laminae of the lateral geniculate nucleus showed little retrograde atrophy; marked degeneration was found in the medial interlaminar nucleus and the pulvinar complex. In addition, interocular transfer of form discriminations to the eye on the injured side was absent or poor, while transfer in the opposite direction was normal. A cat with a suprasylvian lesion undercutting areas 17 and 18 was unable to learn pattern discriminations with the eye on the injured side, in spite of prolonged training with that eye and normal learning with the other eye. Another cat with a suprasylvian lesion selectively removing the anteromedial and posteromedial portions of the lateral suprasylvian area showed no learning deficit on the injured side, but p o o r transfer to that side. A learning deficit on the side of the lesion emerged in this cat after forebrain commissurotomy. The results support the hypothesis of a major involvement of cortical areas outside of 17 and 18 in the processes of abstraction and generalization of visual information necessary for learning and interhemispheric transfer of form discrimination in the cat. Key words: Split-chiasm cats - Cortical lesions - Form Discrimination Visual learning - Interocular and interhemispheric transfer
Offprint requests to. Dr. G. Berlucchi (address see above)
0 0 1 4 - 4 8 1 9 / 7 9 / 0 0 3 4 / 0 5 5 1 / $ 4.80
552
G. Berlucchiet al.
We have recently reported that split-chiasm cats retain their capacity for interocular transfer of form discriminations following unilateral or bilateral lesions of the visual cortical areas 17, 18, and 19 (Berlucchi et al., 1978b). Since section of the main cortical commissure, the corpus callosum, abolishes interocular transfer of pattern discriminations in split-chiasm cats (Myers, 1956; Sperry et al., 1956), it follows that cortical areas other than 17, 18, and 19 are sufficient for ensuring the interhemispheric exchange of visual information required for interocular transfer following splitting of the optic chiasm. In the present experiment we have tested the effects of unilateral lesions of the middle and posterior suprasylvian gyri on interocular transfer of form discriminations in split-chiasm cats. In addition to an important portion of area 19, the middle and posterior suprasylvian gyri contain a number of cortical areas (Otsuka and Hassler, 1962; Sanides and Hoffmann, 1969; Heath and Jones, 1971; Palmer et al., 1977; Sprague et al., 1977; Tusa, 1978) which receive visual information from the lateral geniculate nucleus ( L G N d ) and/or from parts of the pulvinar nuclei which in turn are innervated by projections from the superior colliculus and pretectum (Altman and Carpenter, 1961; Niimi et al., 1970; Graybiel, 1972a, 1972b; Rosenquist et al., 1974; Itoh, 1977; Graham, 1977; Berman, 1977). These areas are also supplied with reciprocal callosal connections with the eontralateral hemisphere, and these connections do not appear to be limited to the representations of the vertical meridian of the visual field (Heath and Jones, 1970, 1971), in clear contrast to the organization of the callosal connections of area 17, 18, and 19 (Berlucchi, 1972). The importance of suprasylvian areas for visual discrimination in the cat has recently been indicated by a number of studies (Hara et al., 1974; Wood et al., 1974; Alder and Meikle, 1975; Cornwell et al., 1976; Sprague et al., 1977; Baumann and Spear, 1977). These same areas have been shown to contain neurons with large receptive fields, often extending across the vertical meridian of the visual field (Hubel and Wiesel, 1969; Wright, 1969; Dow and Dubner, 1971; Spear and Baumann, 1975; Turlejski and Michalski, 1975; Camarda and Rizzolatti, 1976; Palmer et al., 1977). A study of the neural basis of interocular and interhemispheric transfer of visual learning in the monkey has emphasized the critical importance of neurons with similar receptive fields (Gross and Mishkin, 1977), thus suggesting an analogous role for the neurons in the suprasylvian areas of the cat. The present study shows that both learning and interhemispheric transfer do indeed suffer from removal of these areas.
Methods Surgery and Histology
All surgical procedureswere carried out in 7 cats under Nembutal anesthesia (35-40 mg/kg, i.p.). The optic chiasm was sectioned as described by Myers (1955) and the forebrain commissureswere sectioned as describedby Berlucchi(1966), Sperry (1968) and Trevarthen (1972) after retraction of the hemisphere contralateral to a cortical lesion. Cortical lesions were made by subpial aspiration. Histological preparation and analysis were the same as described by Sprague et al. (1977). Cortical lesions were reconstructed both by examinationof coronal sections and by evaluation of the
Learning and Interhemispheric Transfer of Visual Pattern Discriminations
553
l+rl Fig. 1. Pairs of forms used in discrimination training. In each pair the two black forms have equal area. Size of stimuli in the figure is reduced to about 1/20 of that of the stimuli used in the discrimination box. Positive stimulus is on the left except for Problem 1
+l,.e~
L xl
retrograde atrophy in the thalamus. Designation of cortical areas is taken from the work of Tusa et al. (1975), Palmer et al. (1977), and Tusa (1978) and is illustrated by Sprague et al. (1977) and Berlucchi et al. (1978b).
Training Apparatus, Testing Proceduresand Experimental Design The training apparatus has been described in detail elsewhere (Berlucchi and Marzi, 1970; Berlucchi et al., 1972; Berlucchi et al., 1978a, 1978b). Briefly, the discriminanda were presented on two side-by-side top-hinged doors illuminated from behind. In order to obtain a reward consisting of a sinai1 piece of beef kidney, the cat, which had been food-deprived for about 24 h, had to push open the door displaying the positive stimulus. The other door was locked. After an error which consisted in pushing the locked door, correction was allowed. Following the attainment of the reward the animal was replaced in the start-box and the next trial began immediately. A daily session consisted of 40 trials, 20 of which were run with the positive stimulus on the right door and 20 with the positive stimulus on the left door. The two stimulus conditions were alternated in a quasi-random order according to a modified Gellermann (1933) sequence. All animals were first trained binocularly on a simple light-dark discrimination, that is with only one door lighted with no patterned stimulus on it (mean luminance 39 cdm-Z), until they reached a learning criterion of two consecutive sessions with no more than four errors in each session. The dark door (mean luminance 0.3 cdm -2) was chosen as the positive stimulus. Following attainment of the learning criterion, each eye was tested separately by covering the other eye with a black plastic occluder. Monocular testing continued until the animal reached the same learning criterion. This procedure served to familiarize the animals with the training apparatus and the monocular testing. The optic chiasm was sectioned in all cats following the above procedure. After a recovery period of at least two weeks, each cat was retrained first binocularly and then monoeularly with the same light-dark discrimination. Subsequently a cortical lesion was placed in one hemisphere of each cat. After a recovery period of at least two weeks, there was a second retesting, both binocular and monocular with each eye, on the light-dark discrimination. This was followed by monocular training and tests of interocular transfer on various pattern discriminations shown in Fig. 1 (numbered 1 to 7). The basic paradigm involved training with one eye until reaching the criterion of two consecutive sessions with at least 90% correct responses, followed by overtraining with the same eye for 5 regular sessions. The eye used for learning was then occluded and the other eye was trained to the same criterion. However, as specified later, two cats (C 50 and C 56) failed to reach above-chance levels of performance when using the eye on the injured side in spite of prolonged training. In each cat, the eye order was reversed from problem to problem, so that the eye on the intact side was used for learning some problems and the eye on the injured side was used for learning other problems. Cats C 47, C 50, and C 52 were tested on 4 pattern discriminations, C 45 on 2, C 53 on 6, C 56 on 3, and Sub 4 on 5, as specified in Table 1. Counterbalancing across cats was used for equafizing the difficulty I of the discriminations learned by intact and injured side, respectively, but such a counterbalancing could 1 The relative difficulty of the discriminations was assessed on the basis of the mean number of errors committed by control split-chiasm and split-brain cats before attaining the criterion of learning of each discrimination (see below)
554
G. Berlucchi et al.
Table 1. Sequence of problems (numbered as in Fig. 1) and eye used for learning in each cat Cat
Problem
Eye used for learning
C 45 lesion on left side
2 3
L R
C 47 lesion on left side
2 4 3 5
R L R L
C50 lesion on right side
8 4 3 5
L R L R
C 52 lesion on right side
2 4 3 5
R L R L
C53 lesion on right side
2 4 3 5 1 6
L R L R L R
C56 lesion on left side
2 4 3
L R R
Sub 4 lesion on left side
3 5 1 6 7
L R L R R
not be perfect because of differences in the number of problems learned by the different cats. Accordingly, further corrections were introduced in the analysis of the results, as indicated in the Results section. After completion of testing on pattern discriminations, the forebrain commissures were completely sectioned in cats C 45, C 47, and Sub 4. These cats were then retested monocularly with each eye on the discriminations learned before commissurotomy, by alternating eyes from session to session. C 45 was then trained with either eye on alternate days on three new discriminations. Cat C 53 was submitted to a suprasylvian lesion in the previously intact hemisphere and tested for retention in the same way as the three commissurotomized cats.
Results
Histology A l l c h i a s m a t i c a n d c o m m i s s u r a l s e c t i o n s w e r e c o m p l e t e , as i n t e n d e d . T h e a n a l y s i s o f t h e c o r t i c a l l e s i o n s is s u m m a r i z e d i n T a b l e 2. C a t s C 47, C 52, C 53,
LG-intact
P S S G - xx
and symbols: LG
damage
AMLS
and/or
- xxx
- xxx
- xxx
- xxx
- xxx
PSSG - x
MSSG
P S S G - xx
MSSG
PSSG
MSSG
PSSG - intact
- xxx
xx
MSSG
- xxx -
MSSG
- intact
PSSG
PSSG
MSSG
Intact
21
atrophy, xx = moderate
and/or
- xx
- xxx
- x
PMLS
AMLS
Caudal
1/3 - NIM - xx
C,C1-2 - xx N I M - xx
1/3:A-A1
Intact except Middle
atrophy, xxx = severe damage
and/or
atrophy
= ant. lat. suprasylv_ area, PLLS
xxx
-
Mid. = dorsal suprasylv, area,
18), MSSG
P.lat.v - xxx
P.inf.
P.lat.v - xxx
PAnE - xx
P . l a t . d -- x
caudal pole
P.lat.v - xxx exc.
= post. lat. suprasylv, area, x = minimal
= ventral syprasylv, area, DLS
half xxx
PAnE - x - xx
P.lat.v - xxx
P.inf.dorsal
P . m e d . ~ _ a - xx
P,lat.v - xxx P.lat.a - xxx
P.inf. - xxx
P . l a t . v - xx - xxx
P.inf. - xxx
P. inf. - xx
Pulvinar
vis. f i e l d , 17 +
medial half xxx
1 / 3 : N I M - xx C, C1-~ - x
A1 - x
Caudal
C,Cl-2-xxx medial tips - xxx
Intact except
A+AI
tips xxx
1/3: NIM-xxx;C,Cl_2-x
1/3: intact
medial
Post. 1/3: NIM-xx;
Middle
Rostral
-
C,C1-2 - xx NIM x
Post 1/3:A+A1
Intact except
E x c . c a u d a l p o l e A + A~
All parts - xxx
vis. f i e l d s 1 9 , 2 1 ) , V L S
= Post.
- xx
- x
Intact except
PMLS
AMLS
Intact except
DLS - xxx
Intact except
P L L S - xx
PMLS
x
1 / 3 : N I M - xx
C,C~_2 -x
A1
middle
Intact except
Intact
LGNd
lat. gyrus (A cent. + upper
- xx
Intact except
DLS+VLS
= post. medial snprasylv, area, ALLS
damage
-
- xxx xxx
P L L S -- x x x
ALLS PMLS
- xxx
xx
PLLS-
AMLS
- xx
PMLS
Intact except
AMLS - xxx PMLS - xxx
Intact except
LSA
18, 19), PLG
xxx
xxx
xxx
xxx
xxx
xxx
Intact
7
= post. suprasylv, gyrus (A cent. + upper
= ant. medial suprasylv, area, PMLS
suprasylv, gyrus (7, 21), PSSG
Intact
xx
Intact
Intact
Intact
Intact
Intact
20
= l a t . g y r u s ( l o w e r vis. f i e l d s , 1 7
1 7 in c a u d a l
s p l . G - xx
LG-intact
PSSG - xxx
Intact except
P L G - xx
LG-intact
PSSG - xxx
P S S G - xx
1 8 in l o w e r
Abbreviations
Sub 4
C 56
xx
LG-intact
xxx
-
Intact except
P L G - xx
(Right
-side)
Intact except
C 53
x
Intact except
PLG
C 52
-
xxx
C 50
PSSG
LG-intact
Intact
C 47
Intact
Intact
19
findings in all cats
C 45
17-18
Table 2. Surmnary of anatomical
5"
-
