Visual Neuroscience (1990), 4, 185-204. Printed in the USA. Copyright © 1990 Cambridge University Press 0952-5238/90 $5.00 + .00 Effects of monocular enucleation, tetrodotoxin, and lid suture on cytochrome-oxidase reactivity in supragranular puffs of adult macaque striate cortex THOMAS C. TRUSK, WAYNE S. KABOORD, AND MARGARET T.T. WONG-RILEY (RECEIVED February 6, 1989; ACCEPTED December 14, 1989) Abstract The laminar structure and cellular distribution of cytochrome-oxidase (CO) reactivity in supragranular puffs of striate cortex was examined in adult macaque monkeys surviving various periods of monocular enucleation, lid suture, and retinal impulse blockage with tetrodotoxin (TTX). Enucleation and TTX produced a rapid and severe loss in the size of the CO reactive region in puffs dominated by the removed or treated eye compared to slower and less marked reductions obtained in deprived puffs of lid-sutured monkeys. In all deprived animals, the cross-sectional areas of deprived puffs decreased most rapidly in the upper layers (2 and 3A). In long-term enucleated (60 wks) and TTX-treated (4 wks) monkeys, puff area was severely reduced in layer 3B, while reactivity in layer 3B appeared partially spared in lid-sutured monkeys. The density of the CO reaction product was significantly and evenly reduced throughout deprived puffs for all of the monkeys examined; however, this decrease was less severe in adult monkeys lid-sutured for 11 wks. Although no evidence for cell loss was obtained, all three forms of visual deprivation led to lower counts of neuronal perikarya with high levels of CO reaction product in both deprived puff and interpuff areas. This effect was less marked in the deprived puffs of monkeys lid-sutured for 2.5 and 3 yrs, suggesting recovery of CO activity in some neurons. Neurons in deprived puffs and interpuffs were generally similar in size to those in nondeprived regions, although CO-reactive cells were significantly smaller in the deprived puffs of monkeys enucleated for 28.5 or 60 wks. These results indicate that the metabolic response of neuronal elements in supragranular striate cortex depends upon the nature of the visual deficit. The partial sparing of CO reactivity in deprived puffs of lid-sutured monkeys may reflect the continued transmission of certain types of visual stimuli through a closed eyelid. Keywords: Macaque striate puffs, Enucleation, Tetrodotoxin, Lid suture, Cytochrome-oxidase histochemistry, Adult metabolic plasticity Introduction Puffs (dots or patches) are the supragranular portions of peri- odic cytochrome oxidase-rich columns (also known as blobs) unique to the primate striate cortex (Horton & Hubel, 1981; Hendrickson et al., 1981; Horton, 1984; Wong-Riley & Carroll, 1984). The local enrichment of cytochrome oxidase (CO), a mi- tochondrial energy-deriving enzyme, indicates that neuronal ele- ments within puffs possess the metabolic capacity to sustain functional activity levels surpassing those in surrounding inter- puff regions (Wong-Riley, 1989). The notion that this parcel- lation may reflect a morphological division of visual function has been verified in physiological studies demonstrating that puff neurons are characteristically more responsive to color, less selective for stimulus orientation, and more sensitive to low spa- tial frequencies than neurons in surrounding interpuff regions Reprint requests to: Thomas C. Trusk, Department of Anatomy and Cellular Biology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wl 53226, USA. (Livingstone & Hubel, 1984; Tootell et al., 1988c; Ts'o & Gil- bert, 1988). In Old World monkeys, apes, and humans, puffs are cen- tered over ocular dominance bands in the major geniculate re- cipient layers 4A and 4C, and the response properties of puff cells tend to be dominated by one eye, more so than neurons ly- ing outside the CO-rich regions (Livingstone & Hubel, 1984; Ts'o & Gilbert, 1988). Monocular treatments such as enucle- ation (Horton & Hubel, 1981; Horton, 1984; Hendrickson & Tigges, 1985), retinal impulse blockade with tetrodotoxin (TTX) (Wong-Riley & Carroll, 1984; Wong-Riley et al., 1989a,6), and eyelid suture (Horton, 1984; Hendry & Jones, 1986) reduce CO reactivity within rows of puffs centered above less CO-reactive ocular dominance bands associated with the deprived eye. This loss of CO reactivity indicates that the high CO activity of neu- ral elements in normal puffs depends heavily upon functional input from a single normal eye, and demonstrates the metabolic plasticity of mature, fully developed visual cortical neurons. Very little is known of the effects of monocular deafferen- tation or deprivation on CO reactivity in supragranular puffs 185