Journal of Neurology, Neurosurgery, and Psychiatry, 1980, 43, 719-724

Colour anomia restricted to the left visual hemifieldafter splenial disconnexionJ ZIHL AND D VON CRAMON

From the Max-Planck-lnstitute for Psychiatry, Munich

S U M MARY In a patient with damage to the right occipital lobe and to the splenium of thecorpus callosum, an incomplete colour anopia in the left upper quadrants and a colour anomiawas found for the complete left visual hemifield beyond 20 eccentricity. The patient had nodifficulty in recognising coloured targets when presented in the periphery of the left visual half-field and in the foveal region, but could not name them correctly. The results suggest that thelesion of the splenium of the corpus callosum disconnects the right visual cortex from thelanguage areas of the left hemisphere, and the specific disturbance of colour naming is theconsequence.

Colour anomia may be a symptom of amnesticaphasia (anomia), a primary aphasic disorderarising from damage to the cortical structuresdirectly subserving language function.' A secondvariety of colour anomia is very often accompaniedby a right sided hemianopia and a dyslexia. Thelatter disturbance of colour naming has beenattributed to an anatomical disconnexion betweenthe visual cortex and the cerebral structures sub-serving language function. This kind of colouranomia is secondary to this disconnexion whilelanguage function remains intact.2 3 In these citedcases colour anomia was present in the remainingintact visual field. The loss of one or both upperquadrants is often accompanied by an inabilityto recognise colours.4 No disturbance of namingcolours, however, was observed for a particularpart of the visual field, for example, for onehemifield. Here we report a case with a lesionincluding the right occipito-temporal region anddamage to the splenium of the corpus callosum.As a consequence colour perception was partiallylost in the left upper quadrants and a disturbanceof colour naming for the left hemifield beyond 20eccentricity was found.

CASE HISTORYA 41 year old Caucasian suffered from frequentacute sinusitis with secondary bronchial infectionsAddress for reprint requests: Dr J Zihl, Max-Planck-Institut furPsychiatrie Kraepelinstrasse 10 D-8000 Munchen 40, W. Germany.Accepted: 20 March 1980

since her childhood. Menorrhagia and metror-rhagia as well as many "bruises" were observedduring the last four years. In June 1979 she suf-fered again from acute sinusitis. A few days latera left-sided hemiplegia with ptosis on the right sidedeveloped within hours, suggesting a right-sidedWeber syndrome. The patient was admitted toanother hospital and became drowsy and eventu-ally comatose. She was said to have remainedunconscious for about two weeks, but no detailedinformation about this period is available. TheCT-scan showed haemorrhage in the medialtemporo-occipital region of the right hemispherepenetrating into the inferior horn of the lateralventricle and into the superior, ambient and inter-penduncular cisterns. The right peduncle had beenslightly compressed by a space-occupying bloodclot.Upon admission examination showed a pale

patient with petechiae and generalised bruising.The spleen was slightly enlarged. The main labora-tory findings were a hypochromatic anaemia, athrombocytopenia (<3000/mm3) with giant plate-lets, a prolonged bleeding time, a reducedmaximal thrombus-elasticity, a pathologicalprothombin-consumption-test and an increasednumber of megakaryocytes in the sternal marrow.On the basis of these findings idiopathic throm-

bocytopenic purpura (chronic-continuous type)was diagnosed. The patient was given steroids inhigh dosage, and the number of thrombocytes in-creased to normal values.

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The patient was transferred to our departmentin November 1979. By that time the neurologicalsigns had receded except for a latent paresis ofthe left arm. The patient was now complaining ofintermittent blurred vision.The CT-scan was repeated in November 1979

(fig 1). There was an enlargement of the collateraltrigone and the inferior horn of the right lateralventricle (1A, B, C). The superior cistern waswidened at least on its right side. A well markedlow density zone was present mainly in the whitematter of the medial temporo-occipital gyri of theright hemisphere. The lesion extended craniallyinto the precuneus (ID) and rostrally into theright half of the splenium of the corpus callosum(IC). Parts of the right hippocampal gyrus andthe cingulate gyrus at its isthmus were probablyalso affected (IB,C).The patient was right-handed, alert and orien-

tated in person, place and time. She did not showany difficulty in verbal expression and compre-hension or in naming objects. She had no alexia

or agraphia. Visual acuity was normal in botheyes.

Methods

Visual perimetry Visual fields were mapped withthe Tubinger perimeter,56 using a target of 116min arc diameter and maximum intensity (320cd/M2) for 900 dynamic perimetry. In addition,static perimetry was performed to determine theprofile of the gradient of light sensitivity along thehorizontal axis and along the 450 axis (right upperquadrant) and the 1350 axis (left upper quadrant)respectively. Visual fields were also mapped withcoloured targets of 116 min arc diameter andmaximum intensity (320 cd/M2). The spectra valuesof the coloured targets were 480 nm for "blue,"525 nm for "green" and 656 nm for "red":Colour fields were also determined using theTubinger perimeter. The patient's task was topress a button whenever she could identify thecoloured target.

Fig 1 Results of CT scans obtained at four different levels. For details see text.

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Colour anomia restricted to the left visual hemifield after splenial disconnexion

In addition critical flicker fusion (CFF) wasdetermined by measuring CFF-fields for 15, 20and 25 Hz (target: 116 min arc diameter; 32 cd/m2). The flickering target was moved with a vel-ocity of about 10/sec from the periphery towardsthe centre of the visual field. The patient wasasked to push a button whenever she could detectthe target flickering.Colour perception and naming The tests oncolour perception and naming within the visualfield were performed with the Tubinger perimeter.Targets of different wavelength (blue: 480 nm;green: 525 nm; yellow: 578 nm; red: 656 nm)were presented at different eccentricities along thehorizontal axis and along the 450 meridian inthe right half-field, and the 1350 and 2250 merid-ians in the left half-field. Target size was always116 min arc diameter, intensity was 320 cd/M2;stimulus duration was either 100 ms or unlimited.Fixation was controlled with an infra-red camera.The patient's task was to compare the colour ofa given target presented beyond 20 eccentricitywith the colour of several foveally presented tar-gets, and to indicate, whether the colour was thesame or different. For colour naming, targetswere presented at a given position in the left orright visual hemifield, or foveally. The patient wasinstructed to name the colour of the target.

In addition to the colour tests with the per-

imeter, the Farnsworth-Munsell 100-hue test wasused.7 Furthermore, a slide with 60 differentcoloured written colour names (for example,"blue" written in red letters) was presented andthe patient was asked to name the colour of thewords and-in a second session-to read thewords.Object naming in the visual field In order to testobject recognition and the naming of objects,symlbols (circle, triangle etc) and figures of objects(a house, an apple etc) were presented tachisto-scopically (exposure duration: 100 ms) in theleft and right visual hemifield. The patient's taskwas to identify the presented figures by namingthem.Reading in the left and right hemifield Lettersand words of appropriate size (for visual acuitybeyond 20 eccentricity) were presented tachisto-scopically (exposure duration: 100 ms) in the leftand right hemifield. The patient's task was to namethe letters and to read the words.

Results

Perimetric data Fig 1A shows the binocularvisual field for white light and the colour visual

fields for blue, green and red test targets. Therewas an incomplete colour anopia in the left upperquadrants indicating a partial loss of colour per-ception in this region of the visual field. Contrastsensitivity, however, was not diminished in theleft hemifield, neither for the horizontal axis norfor the diagonal meridian (1350 meridian as com-pared to the 450 meridian in the right hemifield;cf fig iB). Furthermore, no restriction was foundfor the CFF-fields in the left as compared with theright hemifield.Colour perception and colour naming The resultsfor colour comparison in the left hemifield areshown in table 1. No deficit in colour comparisonwas found along the horizontal meridian and forthe upper and lower quadrants except for a smalldecrease in correct responses for green at 200eccentricity along the 2250-meridian (lowerquadrant) and along the 1350-meridian (upperquadrant).

Table 1 Colour comparison (fovea-left hemifield)Correct responses in percent (n=30) 100 ms stimulusdurationColour Lower quadrant Upper quadrant

10° 15° 200 5° JO 15J

Red 100 100 100 100 100 100Blue 100 100 100 100 100 100Green 100 100 86-7 100 100 93-3Yellow 100 100 100 100 100 100

Colour naming was found to be correct for thefovea and for the right hemifield.

In contrast to these observations, colour namingwas clearly affected in the left hemifield. In theupper quadrant, the test was performed only up to10° eccentricity, because the border of the colourfield for "red" was at 120 eccentricity. Whencoloured targets were presented along the hori-zontal meridian, a gradual decrease of correctresponses was obtained. "Green" was first affected(at 30 eccentricity), followed by "red" and"yellow." At 200 eccentricity, the percentage ofcorrect responses dropped markedly also for "red"and "yellow." "Blue" was in all cases of incorrectresponse the substituted colour name. Blue tar-gets were always called "blue" (cf table 2).Similar results were obtained for different positionsalong the 1350-meridian and 2250-meridian (upperand lower quadrants) in the left hemifield. Acomparable decrease in the percentage of correctresponses was found; the order of the decreasewas quite the same (green, red and yellow; tables3 and 4). There was no clear difference betweenthe two quadrants. Also in these tests, "blue" wasalways named correctly; the other coloured targets

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./Zil.il antid 1) (C tnom

A 01

03

r 1-0

c 32

E 10

L,, 32a

100

320

600 400 200LVF

B

00 200 400 60'RVF

Fig 2 Binocular visual field (up to 60 eccentricitv) for twlite l/lit and coloured targets (A ) and profile oflig/lt sensitil'it3' along tile hloriolontal axi.s and thle diagonial meridians in tile uipper quadrants (B). The visualfield for colours (A ) is restricted in tile left upper quadrant (R: red target, G: green target: B: blue target).No difference was folund for liglht sensitivityv between tlhe left and rigllt Ileinifield along the hlorizontal axis(filled circles) and thle 4S°-meridian (R F) and 13i.5-mzeridian (LVF), respectivelY.

Table 2 Colour n1amingtg alotlg the left iorizontalmeridian Correct responmes in percen t (=-30) A:.100 in s stimnu!u.s duration B: unlimnited duratiotn

(/lour Eccentricit v

2 3 5 I() IS 20(

Red A 100 100 100 73356' 7 100B 100 100 100 73 3 60 0 13 3

Blue A 100 100 100 100 100 100B 100 100 100 100 100 100

Green A 100 66-7 23-3 6 7 6-7 0 00B 100 73 3 33 .3 10 0 6 7 0 00

Yellou A 100 100 100 73 3 60 0 16 7B 100 100 10() 70 0 63 3 20()

Table 3 Colour nam?inlg in thle left lower quadratitCorrect responses in percentit (n=30) A: 100 inuStim ulus dulration B. unilimited durationi

Colour Eccentricit v

2 3 5 10 25)

Red A 100 90.0 40 0 23 3 0 00B 100 93 3 50s0 26 7 000

Blue A 100 100 100 100 100B 100 100 100 100 100

Green A 100 53 3 10 0 6.7 0 00B 100 60 0 10 0 13 3 0 00

Yello,A A 100 100 100 80 0 60 0B 100 100 100 76 7 73.3

(green. red and yellow) were mostly called as"blue," when they were named incorrectly. Thepatient was not aware of the consistentmisnaming.The performance on the Farnsworth-Munsell

100-hue test was diminished in all parts of thespectrum except for blue (fig 2). The patient had

Table 4 Colour nam7?ing in tile left upper quaclral-tCorrect re.spon.se.s in percent (nt30) A: /00 inisstimnulu.s duration B: unzlitmzited durationi

Colour Eccentoriitv

2 3 5 1i

Red A 100 90.0 40 0 23'3B 100 867 43*3 267

Blue A 100 100 100 10(B 100 100 100 1t(1

Cireen A 100 533 100 6-7B 100 60 0 10 0 13 3

Yellou A 100 100 100 80()B 100 100 100 76-7

no problems to assign the correct name to thecolours in which words are written (for example."blue" when the term "red" was written in blueletters), or to read the word for a colour writtenin an another colour (for example. "green" whenwritten in yellow or blue letters).Object naming All presented figures (circle. tri-angle. square, house. apple. dog, faces) wereidentified and named correctly by the patientirrespective to whether they were presented in theleft or right hemifield.Letter and word recognition The patient had nodifficulty in recognising letters and words presentedin either half-field.

Discussion

The main findings described in this report are (I)a partial loss of colour vision in the left upper

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Colour anomia restricted to the left visuial hemifield after splenial disconnexion

Fig 3 Farnsworth-Munsell 100-hue test (binocular condition). The extent of radialdisplacement indicates the degree of disturbed hue discrimnination in that part of thespectrum. Note the good performance in the blue part of the spectrum.

quadrant and a reduced performance on theFarnsworth-Munsell 100-hue test except for theblue part of the spectrum, and (2) a colour anomiain the left hemifield beyond 20 eccentricity (wherecolour vision was preserved). This colour anomiawas not accompanied by an alexia or agnosia forvisual objects.The partial loss of colour vision in the

Farnsworth-Munsell test is in agreement with thefindings in patients with unilateral brain damagereported by other authors, see fcr example refer-ences8 9. The good performance for the blue partof the spectrum in the Farnsworth-Munsell test

may be related to the observation that the colourvisual field for blue in the upper left quadrant isreduced by a lesser extent than the colour fieldsfor green and red targets. The extent of shrinkage

in the colour visual fields in the upper leftquadrants may indicate a lesion involving the con-

nexions from the striate cortex to prestriate corti-cal areas, and to the inferior occipitotemporalregions. Zeki'0 11 has shown that cells in Area V4of the prestriate cortex of the rhesus monkey are

specifically colour-coded. Even though it is not

possible to correlate the damaged region revealedby computed tomography in our patient, with thecolour-coded areas found by Zeki, one mightspeculate about a functional connection of thelesioned area in our patient with Area V4 asdefined by Zeki. It seems, however, that totalloss of colour vision only occurs after bilaterallesions in the infero-temporal region in both man4and monkey (Fries and Zeki, in preparation). Inman, total loss of colour vision was found to be

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J Zihl and D von Cramon

accompanied by visual field defects, and there is astrikingly high incidence of bilateral defectsaffecting the upper quadrants (for a review, seereference 4). The observation that a partial visualfield shrinkage in the upper left quadrants wasonly found for coloured targets suggests a dissoci-ation of colour vision from other visual functions(for example, light sensitivity, critical flickerfusion) and supports the idea of a localised repre-sentation of colour vision in the visual cortex ofman.The colour anomia found in the left hemifield

can be considered as a disturbance due to splenialdamage.'2 13 One may assume that the lesion ofthe splenium of the corpus callosum disconnectsthe areas involved in processing colours of theright visual cortex from the language areas of theleft hemisphere. Colour anomia has not to beaccompanied by an alexia, or an agnosia forvisual objects, as our case indicates. This may betaken as evidence that a splenial disconnexionsyndrome can be restricted to only one visualfunction (see also reference 14).

It has been shown that the peristriate regionsimportant for colour coding have their own cal-losal connections.' 15 16 If we suppose that fibrescarrying colour information from the right prestri-ate cortex to the left hemisphere via the spleniumof the corpus callosum are damaged, the isolateddisturbance of naming colours in only the lefthemifield would be the consequence of this splenialdisconnexion. Colour anomia, therefore, shouldbe considered as a single unitary disturbance. It isnot clear, however, why this anomia did not occurin the complete left hemifield, but only beyond 20eccentricity. Probably either the foveal region isrepresented bilaterally'7 18 or there is an overlapin the cortical representation of the visual fieldacross the vertical axis.'9 20 It remains also unclearwhy performance in colour naming is better alongthe left horizontal meridian as compared with theupper and lower quadrants, as density of colour-coded cells or colour carrying fibres in relation tovisual field regions (for example, the horizontalmeridian) has not been clarified.

In conclusion the results presented here supportthe notion of splenial disconnexion of colournaming from colour perception. The observationswere obtained by testing the two visual half-fieldsfor different visual and visual-verbal tasks. Undernormal (that is, foveal) test conditions the pre-sented disconnexion phenomenon would not havebeen observed.

This work was supported by Deutsche For-schungsgemeinschaft.

References

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2 Geschwind N, Fusillo M. Color naming defectsin association with alexia. Arch Neurol 1966; 15:137-46.

3 Oxbury JM, Oxbury SM, Humphrey NK. Varietiesof colour anomia. Brain 1969; 92:847-60.

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15 Zeki SM. Interhemispheric connections of prestri-ate cortex in monkey. Brain Res 1970; 19:63-75.

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17 Bunt AH, Minckler DS, Johanson GW. Demon-stration of bilateral projection of the centralretina of the monkey with horseradish peroxidaseneuronography. J Comp Neurol 1977; 171:619-30.

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