Ultrastuctural studies of the primate lateral geniculate nucleus: Morphology and spatial relationships of axon terminals arising from the retina, visual cortex (area 17), superior colliculus, parabigminal nucleus, and pretectum of <i>Galago crassicaudatus</i>

Feig, Sherry L.; Harting, John K.

doi:10.1002/cne.903430103

Cited by 51 publications

(54 citation statements)

References 53 publications

(64 reference statements)

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“…1984; Weber and Kalil, 1987;Feig and Harting, 1994). TRN terminals, which are inhibitory and are called F profiles because of the flattened shape of their vesicles, lie adjacent to RL profiles on thalamic dendrites (Harting et al, 1991).…”

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confidence: 99%

Corticocortical communication via the thalamus: Ultrastructural studies of corticothalamic projections from area 17 to the lateral posterior nucleus of the cat and inferior pulvinar nucleus of the owl monkey

Feig

Harting

1998

J. Comp. Neurol.

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Electron microscopic anterograde autoradiography has been used to analyze the morphology and postsynaptic relationships of area 17 cortical terminals in the lateral division of the lateral posterior nucleus (LPl) of the cat and medial division of the inferior pulvinar nucleus (IPm) of the owl monkey. Such terminals are thought to arise exclusively from layer 5 in the cat and primate (Lund et al. [1975] J. Comp. Neurol. 164:287-304; Abramson and Chalupa [1985] Neuroscience 15:81-95). All labeled terminals in both nuclei exhibited the morphology of ascending "lemniscal" afferents. That is, they contained round vesicles, were large, made asymmetrical synaptic and filamentous nonsynaptic contacts, and were classified as RLs. These cortical RLs also exhibited the postsynaptic relationships of lemniscal afferents. Thus, they were presynaptic to large dendrites within glial encapsulated glomeruli, where a majority was involved in complex synaptic arrangements called triads. They also were found adjacent to terminal profiles with pleomorphic vesicles but never adjacent to small terminals containing round vesicles. Our results suggest that the layer 5 projection from area 17 provides a functional "drive" for some LPl and IPm neurons. Information carried over this "re-entrant" pathway (Guillery [1995] J. Anat. 187:583-592) could be modified within the LPl and IPm by both cortical and subcortical pathways and subsequently conveyed to higher visual cortical areas, where it could be integrated with messages carried through the well-documented corticocortical pathways (Casagrande and Kaas [1994] Cerebral cortex New York: Plenum Press).

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Corticocortical communication via the thalamus: Ultrastructural studies of corticothalamic projections from area 17 to the lateral posterior nucleus of the cat and inferior pulvinar nucleus of the owl monkey

Feig

Harting

1998

J. Comp. Neurol.

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“…Feed-forward axons generally have more densely branching, compact terminal arbors with many synapses located on the proximal dendrites of target neurons where synapses are most effective. Feedback axons generally have more sparsely branching, widespread arbors, with fewer, less effective, synapses largely on distal dendrites (11)(12)(13). Feedback connections are also less precisely focused within a sensory representation, reaching a larger proportion of the representation (11,14,15).…”

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confidence: 99%

Is most of neural plasticity in the thalamus cortical?

Kaas

1999

Proc. Natl. Acad. Sci. U.S.A.

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We now have 20 years or more of rapidly accumulating evidence that sensory-perceptual systems, especially at the cortical level, are highly plastic, even in mature mammals (1-3). Much of the evidence comes from deprivation studies where part of the sensory input to a system is removed and the deactivated neurons in the brain stem and cortex recover responsiveness to remaining inputs. The recoveries can be immediate, but they also can have slowly developing components. The rapid reorganizations generally are attributed to a rebalancing of excititory and inhibitory factors within a dynamically maintained system.For various reasons, the major research emphasis has been on reorganizations in cortical sensory representations. Evidence for subcortical plasticity has been much more limited, and it sometimes is questioned. Nicolelis and coworkers (4, 5) have provided some of the most convincing recent evidence for subcortical changes in the receptive fields of neurons in the somatosensory thalamus, and in this issue of the Proceedings they now provide results indicating that the rapid adjustments are partially mediated by feedback inputs from cortex (6). Thus, not only do changes in the sources of activation occur for neurons in the thalamus, but most surprisingly, many of the changes depend on the poorly understood network of feedback connections that descend rather than ascend the hierarchy of processing levels in the somatosensory system. Sensory-perceptual systems consist of subcortical nuclei and cortical areas that are connected in a complex manner, with enough serial components that it is possible to assign hierarchical levels to structures (7). One of the basic features of these systems is that nuclei and areas that project to structures at higher levels nearly always receive projections back from these targets. Connections between the thalamus and cortex and between cortical areas are, with few exceptions, reciprocal. Projections to a higher level are called feed-forward; those to a lower level are feedback. The functions of feed-forward connections are, by far, better understood. The general premise has been that transformations in response properties mediated by local circuits of neurons at one level are relayed for further processing by neurons at the next level. Thus, the response properties of neurons become increasingly complex at higher and higher levels. This simple formulation of sensory processing postulates no clear role for the ubiquitous feedback connections. In a like manner, the general assumption in plasticity experiments has been that changes that occur in the receptive field properties of neurons at one level of the system have been created at that level or have accumulated in relays of information from lower levels. The report of Krupa et al. (6) is important in that it demonstrates that much of the plasticity that is observed at the thalamic level depends on feedback connections from the cortex. This finding challenges us to consider sensory-perceptual systems in the full richness of their...

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“…The morphology of pretectal axons has been described in detail only for PT-LGN projections (Cucchiaro et al, 1991;Feig and Harting, 1994;Uhlrich and Manning, 1995). PT-LGN axons display a varicose or beaded morphology and give rise to GABAergic terminals that contact chiefly interneurons (Cucchiaro et al, 1993;Wang et al, 2002a; present study).…”

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confidence: 70%

“…With the exception of the zona incerta, vLGN, and the CG, the pretectal projections to the PUL were much denser than in all other PT targets. In fact, Schmidt et al (2001) estimated that the PT innervated the PUL and LP in a ratio of 70:30, and our results confirm this approximate proportion.The morphology of pretectal axons has been described in detail only for PT-LGN projections (Cucchiaro et al, 1991;Feig and Harting, 1994;Uhlrich and Manning, 1995). PT-LGN axons display a varicose or beaded morphology and give rise to GABAergic terminals that contact chiefly interneurons (Cucchiaro et al, 1993;Wang et al, 2002a; present study).…”

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Ultrastructural analysis of projections to the pulvinar nucleus of the cat. II: Pretectum

et al. 2005

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The pretectum (PT) can supply the pulvinar nucleus (PUL), and concomitantly the cortex, with visual motion information through its dense projections to the PUL. We examined the morphology and synaptic targets of pretecto-pulvinar (PT-PUL) terminals labeled by anterograde transport in the cat. By using postembedding immunocytochemical staining for γ-aminobutyric acid (GABA), we additionally determined whether PT-PUL terminals or their postsynaptic targets were GABAergic. We found that the main projection from the PT to the PUL is an ipsilateral, non-GABAergic projection (72.4%) that primarily contacts thalamocortical cell dendrites (87.6%), and also the dendritic terminals of interneurons (F2 profiles; 12.4%). The PT additionally provides GABAergic innervation to the PUL (27.6% of the ipsilateral projection), which chiefly contacts relay cell dendrites (84.6%) but also GABAergic profiles (15.4%). These GABAergic pretectal terminals are smaller, beaded fibers that likely branch to bilaterally innervate the PUL and dLGN, and possibly other targets. We also examined the neurochemical nature of PT-PUL cells labeled by retrograde transport and found that most are non-GABAergic cells (79%) and devoid of calbindin. Taking existing physiological and our present morphological data into account, we suggest that, in addition to the parietal cortex, the non-GABAergic PT-PUL projection may also strongly influence PUL activity. The GABAergic pretectal fibers, however, may provide a more widespread influence on thalamic activity. Indexing termsthalamus; visual system; jerk neurons; eye movements; GABA The feline pulvinar nucleus (PUL) receives input from the pretectum (PT; Graybiel, 1972;Berman, 1977;Itoh, 1977;Berson and Graybiel, 1978;Graybiel and Berson, 1980;Weber et al., 1986;Schmidt et al., 2001), as well as a wide array of visual cortical areas (Raczkowski and Rosenquist, 1983;Baldauf et al., 2005). The PUL contains neurons that respond to movements in the visual field and also during saccadic eye movements (for review, see Chalupa, 1991;Casanova, 2003). Likewise, the feline PT contains a variety of cell types that are active during saccadic eye movements or in response to the movement of visual stimuli *Correspondence to: Martha E. Bickford, Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, 500 S. Preston Street, Louisville, KY 40292. E-mail: martha.bickford@louisville.edu. Dr. Zsolt B. Baldauf's present address is Université de Montréal, School of Optometry, Laboratory of Visual Neuroscience CP 6128 succ. centre ville, Montréal, QC H3C-3J7, Canada. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript (Hoffmann and Schoppmann, 1975;Schoppmann and Hoffmann, 1979;Ballas and Hoffmann, 1985;Hoffmann and Distler, 1989;Schmidt and Hoffmann, 1992;Sudkamp and Schmidt, 1995;Schmidt, 1996;Missal et al., 2002). Specifically, pretecto-pulvinar (PT-PUL) cells have large receptive fields, are not directionally selective, and-have been show...

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Ultrastuctural studies of the primate lateral geniculate nucleus: Morphology and spatial relationships of axon terminals arising from the retina, visual cortex (area 17), superior colliculus, parabigminal nucleus, and pretectum of Galago crassicaudatus

Cited by 51 publications

References 53 publications

Corticocortical communication via the thalamus: Ultrastructural studies of corticothalamic projections from area 17 to the lateral posterior nucleus of the cat and inferior pulvinar nucleus of the owl monkey

Corticocortical communication via the thalamus: Ultrastructural studies of corticothalamic projections from area 17 to the lateral posterior nucleus of the cat and inferior pulvinar nucleus of the owl monkey

Is most of neural plasticity in the thalamus cortical?

Ultrastructural analysis of projections to the pulvinar nucleus of the cat. II: Pretectum

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