In human cerebral achromatopsia, extrastriate cortical damage produces
a severe or complete loss of colour vision, with relative sparing of
non-chromatic vision. The critical lesion appears to be in a medial oc
cipitotemporal area, occupying the lingual and caudal fusiform gyri; p
ositron emission tomography has shown that this cortical region is one
of several activated in normal human observers during colour vision t
asks, Attempts to find an analogous 'colour centre' in the cortex of m
onkeys have not been successful, In particular, ablation of cortical a
rea V4, sometimes thought on physiological grounds to be more involved
in wavelength and colour coding than any other visual cortical area,
produces only mild impairments in colour discrimination, In the presen
t study we tested the colour vision of monkeys after cortical ablation
s that mainly or entirely spared area V4. One group of monkeys (group
AT) received ablations in the temporal lobe anterior to area V4, and a
second group (group MOT) received ablations in a medial occipito-temp
oral area roughly corresponding in cranial location to the lesion that
produces human cerebral achromatopsia. The animals in group MOT showe
d no impairment of their colour vision, Group AT, in contrast, had a s
evere impairment in chromatic vision, with a relative sparing of non-c
hromatic vision, Their behaviour was indistinguishable from that of a
human patient with total cerebral achromatopsia who had been tested on
the same tasks. These results show that area V4 in macaque monkeys is
not analogous, and probably not homologous, to the human colour centr
e. Instead, they suggest that the area of the monkey's brain correspon
ding to the colour area in the human brain is in the temporal cortex,
anterior to area V4.