The organization of connections between the pulvinar and visual area MT in the macaque monkey

Standage, Gregg P.; Benevento, L.A.

doi:10.1016/0006-8993(83)91020-x

Cited by 123 publications

(83 citation statements)

References 14 publications

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“…Anatomical studies have revealed anatomical pathways that pass through the superior colliculus and pulvinar (Standage and Benevento 1983;Ungerleider et al 1984), or directly through the lateral geniculate nucleus (Fries 1981;Yukie and Iwaï 1981), to reach the superior temporal sulcus. This pathway likely supports the persistent activity of MT neurons when V1 is inactivated or lesioned (Rodman et al 1989).…”

Section: How Is Such a Rapid Effect Of Feedback Possible?mentioning

confidence: 99%

Feedback Connections Act on the Early Part of the Responses in Monkey Visual Cortex

Hupé

James

Girard

et al. 2001

Journal of Neurophysiology

302

225

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. Feedback connections act on the early part of the responses in monkey visual cortex. J Neurophysiol 85: 134 -145, 2001. We previously showed that feedback connections from MT play a role in figure/ground segmentation. Figure/ground coding has been described at the V1 level in the late part of the neuronal responses to visual stimuli, and it has been suggested that these late modulations depend on feedback connections. In the present work we tested whether it actually takes time for this information to be fed back to lower order areas. We analyzed the extracellular responses of 169 V1, V2, and V3 neurons that we recorded in two anesthetized macaque monkeys. MT was inactivated by cooling. We studied the time course of the responses of the neurons that were significantly affected by the inactivation of MT to see whether the effects were delayed relative to the onset of the response. We first measured the time course of the feedback influences from MT on V1, V2, and V3 neurons tested with moving stimuli. For the large majority of the 51 neurons for which the response decreased, the effect was present from the beginning of the response. In the responses averaged after normalization, the decrease of response was significant in the first 10-ms bin of response. A similar result was found for six neurons for which the response significantly increased when MT was inactivated. We then looked at the time course of the responses to flashed stimuli (95 neurons). We observed 15 significant decreases of response and 14 significant increases. In both populations, the effects were significant within the first 10 ms of response. For some neurons with increased responses we even observed a shorter latency when MT was inactivated. We measured the latency of the response to the flashed stimuli. We found that even the earliest responding neurons were affected early by the feedback from MT. This was true for the response to flashed and to moving stimuli. These results show that feedback connections are recruited very early for the treatment of visual information. It further indicates that the presence or absence of feedback effects cannot be deduced from the time course of the response modulations.

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Section: How Is Such a Rapid Effect Of Feedback Possible?mentioning

confidence: 99%

Feedback Connections Act on the Early Part of the Responses in Monkey Visual Cortex

Hupé

James

Girard

et al. 2001

Journal of Neurophysiology

302

225

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“…Although alternate pathways exist from retina and LGN to extrastriate cortex, their inputs are relatively sparse (Fries, 1981;Yukie and Iwai, 1981;Bullier and Kennedy, 1983;Standage and Benevento, 1983;Kaas and Huerta, 1988). Thus, destruction of V1 eliminates the main source of visual signals delivered to extrastriate cortical areas and presents an opportunity for considerable reorganization.…”

Section: Abstract: Fmri; Retinotopy; Visual Areas; Cortical Plasticimentioning

confidence: 99%

Topographic Organization of Human Visual Areas in the Absence of Input from Primary Cortex

1999

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Recently, there has been evidence for considerable plasticity in primary sensory areas of adult cortex. In this study, we asked to what extent topographical maps in human extrastriate areas reorganize after damage to a portion of primary visual (striate) cortex, V1. Functional magnetic resonance imaging signals were measured in a subject (G.Y.) with a large calcarine lesion that includes most of primary visual cortex but spares the foveal representation. When foveal stimulation was present, intact cortex in the lesioned occipital lobe exhibited conventional retinotopic organization. Several visual areas could be identified (V1, V2, V3, V3 accessory, and V4 ventral). However, when stimuli were restricted to the blind portion of the visual field, responses were found primarily in dorsal extrastriate areas. Furthermore, cortex that had formerly shown normal topography now represented only the visual field around the lower vertical meridian. Several possible sources for this reorganized activity are considered, including transcallosal connections, direct subcortical projections to extrastriate cortex, and residual inputs from V1 near the margin of the lesion. A scheme is described to explain how the reorganized signals could occur based on changes in the local neural connections.

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“…The pulvinar is located in the dorsal thalamus and contains in its inferior, lateral, and medial subdivisions several visual areas that receive projections from striate and extrastriate visual cortex (Maunsell and Van Essen 1983;Standage and Benevento 1983;Ungerleider et al 1983Ungerleider et al , 1984. The functions of the pulvinar are not well understood.…”

Section: Introductionmentioning

confidence: 99%

Functional Imaging of the Human Lateral Geniculate Nucleus and Pulvinar

Kästner

O’Connor

Fukui

et al. 2004

Journal of Neurophysiology

208

172

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. In the human brain, little is known about the functional anatomy and response properties of subcortical nuclei containing visual maps such as the lateral geniculate nucleus (LGN) and the pulvinar. Using functional magnetic resonance imaging (fMRI) at 3 tesla (T), collective responses of neural populations in the LGN were measured as a function of stimulus contrast and flicker reversal rate and compared with those obtained in visual cortex. Flickering checkerboard stimuli presented in alternation to the right and left hemifields reliably activated the LGN. The peak of the LGN activation was found to be on average within Ϯ2 mm of the anatomical location of the LGN, as identified on high-resolution structural images. In all visual areas except the middle temporal (MT), fMRI responses increased monotonically with stimulus contrast. In the LGN, the dynamic response range of the contrast function was larger and contrast gain was lower than in the cortex. Contrast sensitivity was lowest in the LGN and V1 and increased gradually in extrastriate cortex. In area MT, responses were saturated at 4% contrast. Response modulation by changes in flicker rate was similar in the LGN and V1 and occurred mainly in the frequency range between 0.5 and 7.5 Hz; in contrast, in extrastriate areas V4, V3A, and MT, responses were modulated mainly in the frequency range between 7.5 and 20 Hz. In the human pulvinar, no activations were obtained with the experimental designs used to probe response properties of the LGN. However, regions in the mediodorsal right and left pulvinar were found to be consistently activated by bilaterally presented flickering checkerboard stimuli, when subjects attended to the stimuli. Taken together, our results demonstrate that fMRI at 3 T can be used effectively to study thalamocortical circuits in the human brain.

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The organization of connections between the pulvinar and visual area MT in the macaque monkey

Cited by 123 publications

References 14 publications

Feedback Connections Act on the Early Part of the Responses in Monkey Visual Cortex

Feedback Connections Act on the Early Part of the Responses in Monkey Visual Cortex

Topographic Organization of Human Visual Areas in the Absence of Input from Primary Cortex

Functional Imaging of the Human Lateral Geniculate Nucleus and Pulvinar

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