The determination of the projection of the visual field on to the lateral geniculate nucleus in the cat

Abstract

Henschen (1897, 1898) was the first to provide direct evidence in favour of a retinotopic projection in the lateral geniculate nucleus (LGN). He described a woman suffering from blindness of the lower left quadrants of both visual fields who was subsequently found to have a lesion limited to the dorsal half of the right LGN. Actually these early observations are not in accord with the later experimental studies on primates by Brouwer and subsequent workers (see below). Further early human clinico-pathological observations were made by Wilbrand & Saenger (1904), Ronne (1913Ronne ( , 1914 and Winkler (1912), but the extreme rarity of sufficiently restricted lesions, particularly in the nucleus itself, made it unlikely that the details of the retinotopic projection in the LGN would be unravelled in this way.By enucleating the eye of a cat and studying the distribution of the secondary degeneration in each LGN, Minkowski (1913) provided the first direct experimental evidence that the crossed and uncrossed optic fibres were distributed differently in the nucleus (cf. Minkowski, 1920) and that the binocular part of a visual field projected only to the medial part. The first detailed study of the retinotopic projection in the LGN was, however, carried out by Brouwer and his colleagues (Brouwer, Zeeman & Houwer, 1923). By making small retinal lesions and subsequently studying the degenerating fibres in Marchi preparations they established the quadrantic projections of the retina in the rabbit and cat and the quadrantic and intraquandrantic projections of the central and peripheral retinal segments in the monkey (Brouwer & Zeeman, 1925Overbosch, 1927). Further details in respect to the monkey were added by Brody (1934), Penman

Long-range dichoptic interactions in the human visual cortex in the region corresponding to the blind spot

“…Using the conventional system of numbering the layers, 1, 4 and 6 are the layers driven by the contralateral eye, while layers 2, 3 and 5 are driven by the ipsilateral eye. In mammals, the different layers of the LGN are in precise topological register with one another (Bishop, Kozak, Levick & Vakkur, 1962;Pearlman, 1987). In primates the contralateral layers are discontinuous at the locations that correspond to the blind spot.…”

Ephrin-As and Patterned Retinal Activity Act Together in the Development of Topographic Maps in the Primary Visual System

“…TZs from nasal RGCs extend farther anterior along the dLGN than those from temporal retina, whereas dorsal RGC TZs extend farther posterior than those from ventral retina. Columnar TZs are reminiscent of the functional lines of projection that cross eye-specific layers of the dLGN in binocular species, as determined by visually evoked physiological recordings (Bishop et al, 1962;Montero et al, 1967). These columns could indicate the existence of equivalence zones of mapping information in the dLGN, allowing for functional subtypes of RGCs responsible for monitoring the same area of the visual field to segregate, yet still map together in a 3-D structure.…”

GABAergic feedforward projections from the inferior colliculus to the medial geniculate body.

“…This suggests that there is a convergence of classical excitatory and putatively inhibitory projections within the MGB and that an ascending pathway considered as neurochemically unitary in fact contains more than one channel. This striking difference in feedforward input between the auditory thalamus and other thalamic sensory nuclei is surprising since each has similar structural and intrinsic features (5-7), shared physiological properties (8)(9)(10), analogous cortical projection patterns (11)(12)(13), and a closely related neurochemical organization (14,15). The present results suggest that, despite these parallels, there must be differences in circuitry and information processing regimes within the sensory thalamus.…”