(lateral geniculate nucleus) articles in PubMed
- Skellam process with resetting: a neural spike train model. [Journal Article]
- Stat Med 2016 Sep 26SM
- This paper introduces the Skellam process with resetting. Resetting is a modification that accommodates the modeling of neural spike trains. We show this as a biologically plausible model, which code...
This paper introduces the Skellam process with resetting. Resetting is a modification that accommodates the modeling of neural spike trains. We show this as a biologically plausible model, which codes the information content of neural spike trains with three, potentially, time-varying functions. We show that the interspike interval distribution under this model follows a mixture of gamma distributions, a flexible class covering a wide range of commonly used models. Through simulation studies and the analyses of connected retinal ganglion and lateral geniculate nucleus cells, we evaluate the performance of this model. Copyright © 2016 John Wiley & Sons, Ltd.
- Achromatic temporal-frequency responses of human lateral geniculate nucleus and primary visual cortex. [Journal Article]
- Vision Res 2016; 127:177-85VR
- The sensitivity of the sensory systems to temporal changes of the environment constitutes one of the critical issues in perception. In the present study, we investigated the human early visual system...
The sensitivity of the sensory systems to temporal changes of the environment constitutes one of the critical issues in perception. In the present study, we investigated the human early visual system's dependency on the temporal frequency of visual input using fMRI. Blood oxygen level-dependent (BOLD) responses of the lateral geniculate nucleus (LGN) and primary visual cortex (V1) were investigated in a wide frequency range (6-46Hz) with fine frequency sampling (13 frequencies). Subject-specific functional-anatomic ROIs were derived from the combination of the anatomic template masks and the functional maps derived from multi-session fMRI analyses across all 13 stimulation conditions. Using functional-anatomic ROIs, average responses of LGN and V1 were calculated for each frequency. The V1 surface area was further parsed into 7 eccentricity sectors to detail central and peripheral responses. LGN's response revealed fluctuations on a background of non-significant decrease of the BOLD response with increasing stimulation frequency, while V1 response displayed similar fluctuations with a global maximum in the range of 8-12Hz, but a rapid and significant decrease with increasing stimulation frequency especially above 14Hz. This behavior of V1 response valid for both central and peripheral vision emphasizes that the profound low-pass effect of the visual system to visual input emerges in V1, presumably generated by the intra-cortical circuitry of V1 or projections from extra-striate areas. Besides, the high correlation between LGN and V1 BOLD responses across all visual stimulation frequencies supports the oscillatory tuning in thalamo-cortical interactions as previously claimed in electrophysiological studies.
- Representation of Perceptual Color Space in Macaque Posterior Inferior Temporal Cortex (the V4 Complex). [Journal Article]
- eNeuro 2016 Jul-Aug; 3(4)E
- The lateral geniculate nucleus is thought to represent color using two populations of cone-opponent neurons [L vs M; S vs (L + M)], which establish the cardinal directions in color space (reddish vs ...
The lateral geniculate nucleus is thought to represent color using two populations of cone-opponent neurons [L vs M; S vs (L + M)], which establish the cardinal directions in color space (reddish vs cyan; lavender vs lime). How is this representation transformed to bring about color perception? Prior work implicates populations of glob cells in posterior inferior temporal cortex (PIT; the V4 complex), but the correspondence between the neural representation of color in PIT/V4 complex and the organization of perceptual color space is unclear. We compared color-tuning data for populations of glob cells and interglob cells to predictions obtained using models that varied in the color-tuning narrowness of the cells, and the color preference distribution across the populations. Glob cells were best accounted for by simulated neurons that have nonlinear (narrow) tuning and, as a population, represent a color space designed to be perceptually uniform (CIELUV). Multidimensional scaling and representational similarity analyses showed that the color space representations in both glob and interglob populations were correlated with the organization of CIELUV space, but glob cells showed a stronger correlation. Hue could be classified invariant to luminance with high accuracy given glob responses and above-chance accuracy given interglob responses. Luminance could be read out invariant to changes in hue in both populations, but interglob cells tended to prefer stimuli having luminance contrast, regardless of hue, whereas glob cells typically retained hue tuning as luminance contrast was modulated. The combined luminance/hue sensitivity of glob cells is predicted for neurons that can distinguish two colors of the same hue at different luminance levels (orange/brown).
- Measuring Connectivity in the Primary Visual Pathway in Human Albinism Using Diffusion Tensor Imaging and Tractography. [Journal Article]
- J Vis Exp 2016; (114)JV
- In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a c...
In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a correlation between the number of lateral geniculate nucleus (LGN) relay neurons and LGN size has been shown, and based on previously reported reductions in LGN volumes in human albinism, we suggest that fiber projections from LGN to the primary visual cortex (V1) are also reduced. Studying structural differences in the visual system of albinism can improve the understanding of the mechanism of misrouting and subsequent clinical applications. Diffusion data and tractography are useful for mapping the OR (optic radiation). This manuscript describes two algorithms for OR reconstruction in order to compare brain connectivity in albinism and controls.An MRI scanner with a 32-channel head coil was used to acquire structural scans. A T1-weighted 3D-MPRAGE sequence with 1 mm(3) isotropic voxel size was used to generate high-resolution images for V1 segmentation. Multiple proton density (PD) weighted images were acquired coronally for right and left LGN localization. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask. Though DTI provides relatively poor spatial resolution, and accurate delineation of OR may be challenging due to its low fiber density, tractography has been shown to be advantageous both in research and clinically. Tract based spatial statistics (TBSS) revealed areas of significantly reduced white matter integrity within the OR in patients with albinism compared to controls. Pairwise comparisons revealed a significant reduction in LGN to V1 connectivity in albinism compared to controls. Comparing both tracking algorithms revealed common findings, strengthening the reliability of the technique.
- Organization of the Zone of Transition between the Pretectum and the Thalamus, with Emphasis on the Pretectothalamic Lamina. [Journal Article]
- Front Neuroanat 2016; 10:82FN
- The zone of transition between the pretectum, derived from prosomere 1, and the thalamus, derived from prosomere 2, is structurally complex and its understanding has been hampered by cytoarchitectura...
The zone of transition between the pretectum, derived from prosomere 1, and the thalamus, derived from prosomere 2, is structurally complex and its understanding has been hampered by cytoarchitectural and terminological confusion. Herein, using a battery of complementary morphological approaches, including cytoarchitecture, myeloarchitecture and the expression of molecular markers, we pinpoint the features or combination of features that best characterize each nucleus of the pretectothalamic transitional zone of the rat. Our results reveal useful morphological criteria to identify and delineate, with unprecedented precision, several [mostly auditory] nuclei of the posterior group of the thalamus, namely the pretectothalamic lamina (PTL; formerly known as the posterior limitans nucleus), the medial division of the medial geniculate body (MGBm), the suprageniculate nucleus (SG), and the ethmoid, posterior triangular and posterior nuclei of the thalamus. The PTL is a sparsely-celled and fiber rich flattened nucleus apposed to the lateral surface of the anterior pretectal nucleus (APT) that marks the border between the pretectum and the thalamus; this structure stains selectively with the Wisteria floribunda agglutinin (WFA), and is essentially immunonegative for the calcium binding protein parvalbumin (PV). The MGBm, located medial to the ventral division of the MGB (MGBv), can be unequivocally identified by the large size of many of its neurons, its dark immunostaining for PV, and its rather selective staining for WFA. The SG, which extends for a considerable caudorostral distance and deviates progressively from the MGB, is characterized by its peculiar cytoarchitecture, the paucity of myelinated fibers, and the conspicuous absence of staining for calretinin (CR); indeed, in many CR-stained sections, the SG stands out as a blank spot. Because most of these nuclei are small and show unique anatomical relationships, the information provided in this article will facilitate the interpretation of the results of experimental manipulations aimed at the auditory thalamus and improve the design of future investigations. Moreover, the previously neglected proximity between the MGBm and the caudal region of the scarcely known PTL raises the possibility that certain features or roles traditionally attributed to the MGBm may actually belong to the PTL.
- The Metabotropic Glutamate Receptor Subtype 1 Mediates Experience-Dependent Maintenance of Mature Synaptic Connectivity in the Visual Thalamus. [Journal Article]
- Neuron 2016 Sep 7; 91(5):1097-109N
- Neural circuits formed during postnatal development have to be maintained stably thereafter, but their mechanisms remain largely unknown. Here we report that the metabotropic glutamate receptor subty...
Neural circuits formed during postnatal development have to be maintained stably thereafter, but their mechanisms remain largely unknown. Here we report that the metabotropic glutamate receptor subtype 1 (mGluR1) is essential for the maintenance of mature synaptic connectivity in the dorsal lateral geniculate nucleus (dLGN). In mGluR1 knockout (mGluR1-KO) mice, strengthening and elimination at retinogeniculate synapses occurred normally until around postnatal day 20 (P20). However, during the subsequent visual-experience-dependent maintenance phase, weak retinogeniculate synapses were newly recruited. These changes were similar to those of wild-type (WT) mice that underwent visual deprivation or inactivation of mGluR1 in the dLGN from P21. Importantly, visual deprivation was ineffective in mGluR1-KO mice, and the changes induced by visual deprivation in WT mice were rescued by pharmacological activation of mGluR1 in the dLGN. These results demonstrate that mGluR1 is crucial for the visual-experience-dependent maintenance of mature synaptic connectivity in the dLGN.
- Mapping of methionine-enkephalin-arg(6)-gly(7)-leu(8) in the human diencephalon. [Journal Article]
- Neuroscience 2016 Aug 12; 334:245-258N
- Using an immunohistochemical technique, we mapped the immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) (Met-8) (a marker for the pro-enkephalin system) in the human die...
Using an immunohistochemical technique, we mapped the immunoreactive structures containing methionine-enkephalin-Arg(6)-Gly(7)-Leu(8) (Met-8) (a marker for the pro-enkephalin system) in the human diencephalon. Compared with previous studies, we observed a more widespread distribution of Met-8 in the human diencephalon. Met-8-immunoreactive cell bodies and fibers exhibited a more widespread distribution in the hypothalamus than in the thalamus. We observed six populations of Met-8-immunoreactive cell bodies. These perikarya were observed in the paratenial thalamic nucleus, ventromedial and dorsomedial hypothalamic nuclei, lateral hypothalamic area, pallidohypothalamic nucleus and in the paraventricular hypothalamic nucleus (posterior part). In the thalamus, Met-8-immunoreactive fibers were primarily observed in the midline region, whereas in the hypothalamus, these fibers were widely distributed. In general, a moderate/low density of Met-8-immunoreactive fibers was observed in the diencephalic nuclei. A moderate density was observed in the paraventricular thalamic nucleus, reuniens thalamic nucleus, lateral and medial geniculate nuclei, dorsomedial hypothalamic nucleus, paraventricular hypothalamic nucleus (posterior part) and ventromedial hypothalamic nucleus. The present study is the first to demonstrate the presence of clusters of Met-8-immunoreactive cell bodies in the human thalamus and hypothalamus, the distribution of fibers containing neuropeptides in the hypothalamus and the presence of these fibers in several thalamic nuclei. This neuroanatomical study will serve to elucidate the physiological roles of Met-8 in future studies of the human diencephalon.
- Disruption of visual circuit formation and refinement in a mouse model of autism. [Journal Article]
- Autism Res 2016 Aug 16AR
- Aberrant connectivity is believed to contribute to the pathophysiology of autism spectrum disorder (ASD). Recent neuroimaging studies have increasingly identified such impairments in patients with AS...
Aberrant connectivity is believed to contribute to the pathophysiology of autism spectrum disorder (ASD). Recent neuroimaging studies have increasingly identified such impairments in patients with ASD, including alterations in sensory systems. However, the cellular substrates and molecular underpinnings of disrupted connectivity remain poorly understood. Utilizing eye-specific segregation in the dorsal lateral geniculate nucleus (dLGN) as a model system, we investigated the formation and refinement of precise patterning of synaptic connections in the BTBR T + tf/J (BTBR) mouse model of ASD. We found that at the neonatal stage, the shape of the dLGN occupied by retinal afferents was altered in the BTBR group compared to C57BL/6J (B6) animals. Notably, the degree of overlap between the ipsi- and contralateral afferents was significantly greater in the BTBR mice. Moreover, these abnormalities continued into mature stage in the BTBR animals, suggesting persistent deficits rather than delayed maturation of axonal refinement. Together, these results indicate disrupted connectivity at the synaptic patterning level in the BTBR mice, suggesting that in general, altered neural circuitry may contribute to autistic behaviours seen in this animal model. In addition, these data are consistent with the notion that lower-level, primary processing mechanisms contribute to altered visual perception in ASD. Autism Res 2016. © 2016 The Authors Autism Research published by Wiley Periodicals, Inc. on behalf of International Society for Autism Research.
- Neurodegeneration and Neuroprotection in Glaucoma. [Journal Article]
- Yale J Biol Med 2016; 89(1):73-9YJ
- Glaucoma is the principal cause of irreversible blindness in the world. The disease leads to progressive optic nerve degeneration with a gradual loss of retinal ganglion cells. Neurodegeneration in g...
Glaucoma is the principal cause of irreversible blindness in the world. The disease leads to progressive optic nerve degeneration with a gradual loss of retinal ganglion cells. Neurodegeneration in glaucoma extends beyond the eye into the lateral geniculate nucleus and visual cortex, and the disease even shares some characteristics with other central nervous system degenerative disorders. Glaucoma destroys neurons through oxidative stress, impairment in axonal transport, neuroinflammation, and excitotoxicity. Autophagy may promote or inhibit disease progression. Currently, lowering intraocular pressure is the only way proven to delay glaucoma advancement. However, many new therapies are being developed, including antioxidants, adenosine receptor antagonists, Rho-pathway inhibitors, stem cell therapy, and neurotrophic factors. These therapies focus on neuroprotection, and they may eventually halt glaucoma progression or reverse the process of the disease itself.
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- Neural plasticity following lesions of the primate occipital lobe: The marmoset as an animal model for studies of blindsight. [Review]
- Dev Neurobiol 2016 Aug 1DN
- For nearly a century it has been observed that some residual visually guided behavior can persist after damage to the primary visual cortex (V1) in primates. The age at which damage to V1 occurs lead...
For nearly a century it has been observed that some residual visually guided behavior can persist after damage to the primary visual cortex (V1) in primates. The age at which damage to V1 occurs leads to different outcomes, with V1 lesions in infancy allowing better preservation of visual faculties in comparison with those incurred in adulthood. While adult V1 lesions may still allow retention of some limited visual abilities, these are subconscious-a characteristic that has led to this form of residual vision being referred to as blindsight. The neural basis of blindsight has been of great interest to the neuroscience community, with particular focus on understanding the contributions of the different subcortical pathways and cortical areas that may underlie this phenomenon. More recently, research has started to address which forms of neural plasticity occur following V1 lesions at different ages, including work using marmoset monkeys. The relatively rapid postnatal development of this species, allied to the lissencephalic brains and well-characterized visual cortex provide significant technical advantages, which allow controlled experiments exploring visual function in the absence of V1. © 2016 Wiley Periodicals, Inc. Develop Neurobiol, 2016.