Organization of cytochrome oxidase staining in the visual cortex of nocturnal primates (Galago crassicaudatus and Galago senegalensis): I. Adult Patterns

Abstract

The distribution and differential staining patterns of cytochrome oxidase (CO) activity in visual cortical areas have provided useful anatomical markers for the modular organization of area 17 (striate cortex) and area 18 in primates. In macaque and squirrel monkeys, previous studies have shown that the majority of cells that lie in areas of high CO activity are color selective, are nonoriented, and project to adjacent zones of high CO activity in area 17 and to stripes of high CO activity in area 18. By contrast, most cells in zones with weak CO activity in area 17 have relatively narrow orientation tuning and are not color selective (Livingstone and Hubel: J. Neurosci. 4:309-356, 2830-2835, '84; 7:3371-3377, '87). The periodic organization of CO activity in area 17, the "blobs," and the stripe-like organization in area 18 thus seem to define visual cortical processing modules and/or channels in primates. We have investigated the organization of CO activity in areas 17 and 18 in two species of nocturnal prosimian primates [Galago crassicaudatus (GCC) and Galago senegalensis (GSS)] in order to evaluate CO staining patterns in primates that have been reported to possess almost exclusively rod retinae and no color vision. In area 17 of both species, our results show that, as in diurnal and nocturnal simian primates, the darkest CO staining occurs in layers III and IV, with clear periodicity in layer III (i.e., CO blobs) and homogeneous staining in layer IV beta, the cortical recipient sublayer of the geniculate parvocellular layers. In GCC, individual blobs in layer III appear to be larger and less frequent than has been reported for the macaque monkey. Unlike simian primates, both galago species exhibit clear CO periodicities within layer IV alpha, the cortical recipient sublayer of the magnocellular geniculate layers. In addition, faint CO periodicities are apparent in layer VI and scattered large darkly CO stained pyramidal cells are visible throughout layer V. Quantitative analysis suggests that CO periodicities are more frequent in GSS than in GCC, suggesting that there may be evolutionary pressure to maintain the same number of CO modules within the smaller striate cortex of the lesser galago, although this is not the trend found across distantly related species. CO activity in area 18 is less well-developed than reported in other primates. In fact, we could not reliably identify discontinuities in CO staining in area 18 of GSS.(ABSTRACT TRUNCATED AT 400 WORDS)

An interdigitated columnar mosaic of cytochrome oxidase, zinc, and neurotransmitter-related molecules in cat and monkey visual cortex.

“…Likewise, the association with color is unlikely to be obligatory, given the cat's poor color-vision capacities (28) and the presence of cytochrome oxidase blobs in primates without color vision (29). Our findings are consistent with at least two of the remaining functional interpretations.…”

Expression of immediate-early genes reveals functional compartments within ocular dominance columns after brief monocular inactivation

“…The histological patterns shown in this paper are expected to reflect underlying differences in neuron con- Although we did not detect strong IEG mRNA signals in layers 4B and 4C␣, previous reports can be referred to for the structure (8,25). (B) Our schematic view of changes of IEG expression showing the distribution of somas of active neurons after MI by TTX or MD by eyelid suture (in this case, the left eye).…”

“…Border strips of the left and right eye columns adjoin each other with the boundary of ODCs between them. Previously, Horton and Hubel (3) described CO blobs that included infragranular layers in macaques, and the existence of dim CO blobs in infragranular layers has been suggested for squirrel monkeys and prosimian galagos (7,8). Horton and his colleagues have also suggested the existence of border strips along ODCs in layer 4C in terms of a gap between anterograde tracer signals from the open eye and CO enzymatic activity after long-term MI (5) and pale stripes in layer 4C in CO staining in monkeys with experimental strabismus (9).…”

Functional Organization of Owl Monkey Lateral Geniculate Nucleus and Visual Cortex

“…The pattern of geniculocortical and intracortical connec-and P cells (Irvin et al 1986(Irvin et al , 1993Norton and Casagrande 1982;Norton et al 1988). If this pathway does provide a tions in primates (reviewed in Casagrande 1994;Casagrande and Kaas 1994;) suggests that blob and major input to CO blobs, the differences observed between macaque and owl monkey CO blobs might reflect differences interblob regions may receive different patterns of M and P inputs.…”