TY - JOUR. T1 - Activation of lateral geniculate neurons by norepinephrine. T2 - Mediation by an α-adrenergic receptor. AU - Rogawski, Michael A. AU - Aghajanian, George K.. PY - 1980/1/27. Y1 - 1980/1/27. N2 - Adrenergic receptors in the vicinity of neurons in the lateral geniculate nucleus (LGN) of the rat were pharmacologically characterized using extracellular single-cell recording and microiontophoretic techniques. Application of norepinephrine (NE) at low iontophoretic currents (1-15 nA) produced a delayed activation of most LGN neurons. This activation was mimicked by various sympathomimetic amines. The relative potency series of agonists was typical of postsynaptic α-adrenergic receptors: epinephrine, NE , phenylephrine ≥ α-methylnorepinephrine , dopamine , isoproterenol. The α-antagonists phentolamine, piperoxane and WB-4101, when applied at low iontophoretic currents (,10 nA), produced a selective, dose-dependent and reversible blockade of the response to NE. The β-antagonist ...
NT-4-mediated rescue of lateral geniculate neurons from effects of monocular deprivation.s profile, publications, research topics, and co-authors
An important factor of the dV/dt of an evoked EPSP is the nature of the postsynaptic receptor involved. Ionotropic receptors are associated with fast postsynaptic potentials (PSPs), whereas activation of metabotropic receptors produce much slower PSPs. The major neurotransmitters producing EPSPs in geniculate relay cells are glutamate and acetylcholine, and each can activate both ionotropic and metabotropic receptors (for review, see Sherman and Guillery, 1996). Regarding glutamatergic inputs, retinal afferents activate only ionotropic receptors and thus fast EPSPs, but cortical afferents also activate metabotropic glutamate receptors and can thus evoke slow EPSPs. Ionotropic (nicotinic) and metabotropic (muscarinic) cholinergic receptors are activated via axons from the parabrachial region of the brainstem.. For a thalamic relay cell in burst mode, the present results are consistent with evidence that EPSPs generated via ionotropic receptors are fast enough to activate LTSs and burst firing ...
Background The dorsal lateral geniculate nucleus (dLGN) of the mouse has been an important experimental model for understanding thalamic circuit development. The developmental remodeling of retinal projections has been the primary focus, however much less is known about the maturation of their synaptic targets, the relay cells of the dLGN. Here we examined the growth and maturation of relay cells during the first few weeks of life and addressed whether early retinal innervation affects their development. To accomplish this we utilized themath5 null (math5−/−) mouse, a mutant lacking retinal ganglion cells and central projections. Results The absence of retinogeniculate axon innervation led to an overall shrinkage of dLGN and disrupted the pattern of dendritic growth among developing relay cells. 3-D reconstructions of biocytin filled neurons frommath5−/− mice showed that in the absence of retinal input relay cells undergo a period of exuberant dendritic growth and branching, followed by branch
Coordinated changes in gene expression underlie the early patterning and cell-type specification of the central nervous system. However, much less is known about how such changes contribute to later stages of circuit assembly and refinement. In this study, we employ single-cell RNA sequencing to develop a detailed, whole-transcriptome resource of gene expression across four time points in the developing dorsal lateral geniculate nucleus (LGN), a visual structure in the brain that undergoes a well-characterized program of postnatal circuit development. This approach identifies markers defining the major LGN cell types, including excitatory relay neurons, oligodendrocytes, astrocytes, microglia, and endothelial cells. Most cell types exhibit significant transcriptional changes across development, dynamically expressing genes involved in distinct processes including retinotopic mapping, synaptogenesis, myelination, and synaptic refinement. Our data suggest that genes associated with synapse and ...
Our experiments ruled out the possibility that orientation selectivity in the dLGN may arise from cortical feedback. Three other mechanisms may underlie orientation selectivity in the mouse dLGN: (1) individual dLGN cells may combine inputs from the RGCs whose RFs are displaced spatially; (2) dLGN cells may directly inherit their selectivity from selective RGCs; and (3) the dLGN may compute orientation selectivity locally.. The convergence ratio from RGCs to dLGN cells is known to be low (2-3:1; Chen and Regehr, 2000), making the first mechanism likely (but note that more RGCs may indirectly influence single dLGN cells through their gap junctions with other RGCs; Völgyi et al., 2009). For example, if a dLGN cell receives inputs from two RGCs, any spatial displacement of the RGCs RF centers will potentially lead to an orientation bias. This possibility is supported by our observations of multiple-peak RFs in some dLGN cells and the correlation between the preferred orientation and RF shape. ...
The major mammalian subcortical visual structures receive topographically ordered projections from both eyes. In the adult dorsal lateral geniculate nucleu
The visual thalamus of rodents has served as an important model for exploring the cellular and molecular mechanisms that underlie neural circuit formation. The overwhelming majority of these studies have focused on inputs to and projections from the dorsal lateral geniculate nucleus (dLGN). Relay neurons within dLGN receive strong glutamatergic inputs from retinal ganglion cells (RGCs) and serve as the principle conduit of visual signaling to the cortex. However, relay neurons do not act as passive relays of visual information. The gain of retinogeniculate signal transmission is modulated by nonretinal inputs to dLGN. These nonretinal inputs arise from visual cortex, pretectum, brainstem, thalamic reticular nuclei, and local dLGN interneurons, and they far outnumber the more powerful retinal inputs [1, 2]. In fact, nonretinal inputs account for as much as 95% of the nerve terminals in dLGN [1, 3-6].. Differences in the functional properties of inputs to dLGN translate into distinct neurochemical ...
Vision provides a critical interface with the physical world. This work examines visual development and vision loss in mice to glean the influence of the retinal state on visual connections. I first assessed the impact of retinal activity on the eye-specific segregation of retinal afferents in the lateral geniculate nucleus (LGN) of young Gβ5 -/- mice. Gβ5 is the fifth member of the β subfamily of heterotrimeric G proteins. Gβ5 binds and stabilizes the R7 family of regulators of G-protein signaling (RGS), which accelerate Gi/o GTP hydrolysis. Gβ5 -/- mice, which lack R7RGS activity, have malformed synapses in the outer plexiform layer (OPL) and impaired OPL transmission. Altered spontaneous retinal activity in Gβ5-/- mice at P7, P12, P14, and P28 correlates with impaired eye-specific segregation of retinal afferents in the LGN at corresponding timepoints. However, Gβ5-/- mice exhibit a normal transition from cholinergic to glutamatergic drive that corresponds with a temporary recovery of
Lateral geniculate nucleus aka Corpus geniculatum laterale in the latin terminology and part of brainstem and related structures. Learn more now!
The optic tract conducts information from the chiasm to the lateral geniculate body. ... Fibers from the Lateral Geniculate Body curve around the lateral ventricle in ... – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 104c4e-NDMyY
Previous case reports have described the occurrence of ARN syndrome after HSV encephalitis (3, 4). On the basis of electron microscopic analysis of the distribution of HSV antigens in the retina, optic nerve, and brain of patients with herpetic retinitis and encephalitis, the virus is generally assumed to spread by retrograde axonal transport through the optic nerve and to invade retinal tissue directly. In contrast, viral meningitis following ARN syndrome is rare.. Three previous reports of CT or MR findings of ARN syndrome have noted optic-nerve enlargement and abnormal enhancement of the optic nerves and chiasm on postcontrast T1-weighted images, and high-intensity signal abnormalities on T2-weighted images in the region of the optic tract and lateral geniculate body (5-7). In our case, the MR images showed signal abnormalities in the region of the lateral geniculate body and occipital lobe that were greater on the left side even though the main lesion was located on the retina of the right ...
Synapses made by local interneurons dominate the intrinsic circuitry of the mammalian visual thalamus and influence all signals traveling from the eye to cortex. Here we draw on physiological and computational analyses of receptive fields in the cats lateral geniculate nucleus to describe how inhibition helps to enhance selectivity for stimulus features in space and time and to improve the efficiency of the neural code. Further, we explore specialized synaptic attributes of relay cells and interneurons and discuss how these might be adapted to preserve the temporal precision of retinal spike trains and thereby maximize the rate of information transmitted downstream.
The medial geniculate body (MGB) of the thalamus is a key component of the auditory system. It is involved in relaying and transforming auditory information to the cortex and in top-down modulation of processing in the midbrain, brainstem, and ear. Functional imaging investigations of this region in humans, however, have been limited by the difficulty of distinguishing MGB from other thalamic nuclei. Here, we introduce two methods for reliably delineating MGB anatomically in individuals based on conventional and diffusion MRI data. The first uses high-resolution proton density weighted scanning optimized for subcortical grey-white contrast. The second uses diffusion-weighted imaging and probabilistic tractography to automatically segment the medial and lateral geniculate nuclei from surrounding structures based on their distinctive patterns of connectivity to the rest of the brain. Both methods produce highly replicable results that are consistent with published atlases. Importantly, both methods rely
2. 10% goes to the superior colliculus in the midbrain. 3. Hypothalamus (SCN-circadian rhythm). 4. Pretectum-reflex control of the pupil and lens E. Lateral geniculate nucleus (LGN). 1. Part of the dorsal thalamus. 2. Arranged in six (6) layers (Draw--bended knee; 6 dorsal, 1 ventral). 3. Layers 1 + 2 (most ventral) contain large neurons and are referred to as magnocellular LGN layers. 4. Layers 3 - 6 contain small neurons and are referred to as parvocellular LGN layers.. 5. The information from the two separate eyes is kept separate by projecting to different layers of the LGN. a. Remember the nasal retinal sees the temporal part of the hemifields.. i. This information crosses over. b. The temporal retina of the opposite eye sees the retinal part of the opposite hemifield. i. This information does not cross over. F. Connection between retina and LGN. (Given the left hemifield). 1. Nasal retina projects to layers 1, 4 and 6. a. Information about the temporal part is seen by the nasal retina of ...
The activation of many different receptors subtypes is capable of abolishing the generation of spindle waves and promoting the generation of single spike activity. This transition is similar to that associated with moving from slow wave sleep to waking or REM sleep. In thalamocortical relay cells the activation of muscarinic, alpha-1 adrenergic, H1-histaminergic, or glutamate metabotropic receptors results in the reduction of a leak potassium current and the depolarization of the cell. In addition, the activation of beta-adrenergic, serotoninergic, and H2-histaminergic receptors results in the abolition of spindle waves through the enhancement of the H-current.. In Perigeniculate neurons, the activation of alpha1-adrenoceptors, serotoninergic-2 (or 1C) receptors, or glutamate metabotropic receptors results in the depolarization of these cells and a block of spindle wave generation.. ...
a neural structure that serves as the last of a series of processing centers along the auditory pathway from the cochlea to the temporal lobe of the cerebral cortex. ...
The dorsal lateral geniculate nucleus (dLGN) of the thalamus is the exclusive relay of retinal information en route to the visual cortex. Although much of our ...
Translation for: nucleus (cell, biology) in English->Japanese (Kanji) dictionary. Search nearly 14 million words and phrases in more than 470 language pairs.
The brain is an ensemble of very complicated architecture, and its hard to separate every component and study the pieces individually," says Lucio Schiapparelli, PhD, a neuroscientist in Clines lab and a lead author of the study. "Our methodology allowed us examine the visual system in a way that had not been studied before so we could observe the molecules independently and analyze their biochemistry.". Going into the study, Cline said she was curious whether similar types of proteins would travel to distinct targets within the brain. The retina projects proteins into more than 30 different areas of the central nervous system, but for the study, her team chose to evaluate the two major targets: the superior colliculus (which analyzes motion in the visual field and controls goal-directed head and eye movements), and the lateral geniculate nucleus (which analyzes the shape of objects we see and sends that information to a higher brain area, the visual cortex).. While previous studied identified ...
Split history for Ligand Pharmaceuticals Inc. Stock LGND has had 1 split. Review with ratios, actual prices and calculator for shares.
subjective influences (hand temperature/moisture, off-center or angled specimen insertion etc.) are eliminated for high test-result ...
subjective influences (hand temperature/moisture, off-center or angled specimen insertion etc.) are eliminated for high test-result ...
The histological effect of oral administration of sildenafil citrate (Viagra), commonly used as an aphrodisiac and for the treatment of erectile dysfunction on one of the visual relay centres namely the lateral geniculate body (LGB) of adult Wistar rat was carefully studied. The rats of both sexes (n=24), average weight of 202g were randomly assigned into three treatment (n=18) and control (n=6) groups. The rats in the treatment groups A, B and C received respectively, 0.25mg/kg, 0.70mg/kg and 1.43mg/kg body weight of sildenafil citrate base dissolved in distilled water daily for 30 days, through orogastric feeding tube, while that of the control group D, received equal volume of distilled water daily during the period of the experiment. The rats were fed with growers mash obtained from Edo Feeds and Flour Mill Ltd, Ewu, Edo State, Nigeria and were given water liberally. The rats were sacrificed on day thirty-one of the experiment. The lateral geniculate body (LGB) was carefully dissected ...
We present a spiking neural network model of the thalamic Lateral Geniculate Nucleus (LGN) developed on SpiNNaker, which is a state-of-the-art digital neuromorphic hardware built with very-low-power ARM processors. The parallel, event-based data processing in SpiNNaker makes it viable for building massively parallel neuro-computational frameworks. The LGN model has 140 neurons representing a `basic building block for larger modular architectures. The motivation of this work is to simulate biologically plausible LGN dynamics on SpiNNaker. Synaptic layout of the model is consistent with biology. The model response is validated with existing literature reporting entrainment in steady state visually evoked potentials (SSVEP) --- brain oscillations corresponding to periodic visual stimuli recorded via electroencephalography (EEG). Periodic stimulus to the model is provided by: a synthetic spike-train with inter-spike-intervals in the range 10 -- 50 Hz at a resolution of 1 Hz; and spike-train output from a
1 . Sen-Bhattacharya B, Serrano-Gotarredona T, Balassa L, Bhattacharya A, Stokes AB, Rowley A, Sugiarto I, Furber S (2017) A Spiking Neural Network Model of the Lateral Geniculate Nucleus on the SpiNNaker Machine. Front Neurosci 11:454 [PubMed] ...
Purpose: Anterograde trans-synaptic degeneration along the visual pathway has been observed in glaucomatous patients and experimental glaucoma models. The aim of this study is to investigate the mechanisms and extent of trans-synaptic changes in the visual system as well as in the distant somatosensory cortex using a rodent model of optic nerve axotomy. It is known that the rat primary somatosensory centre has structural and functional inter-linkages with the visual cortex.. Methods: Optic nerve injury in the form of axotomy was performed in adult Sprague-Dawley rats. Animals were sacrificed at regular time points and tissues harvested. Immunoblotting followed by densitometric analysis was used to determine the phosphorylation profile of Akt in the dorsal lateral geniculate nucleus (dLGN), the visual cortex and the primary somatosensory cortex (S1). The neuronal cell size and cell density were measured using Nissl staining. The prevalence of apoptosis was characterized by terminal ...
In the mammalian visual system, sensory information captured by the retina is routed through the lateral geniculate nucleus (LGN) of the thalamus before reaching the cerebral cortex. The lateral geniculate circuits thus operate as a gateway for visual information flowing from the sensory periphery to the central nervous system. Traditionally, the LGN has been regarded as a passive relay station rather than an active processing center because the receptive fields of geniculate neurons closely resemble those of retinal ganglion cells. This simplistic view, however, is at odds with the complexity of the thalamic neural circuits - the LGN houses a substantial population of inhibitory neurons that can modulate the activity of the thalamocortical projecting neurons. How do the excitatory and inhibitory neurons in the LGN form circuits to process visual information from the retina to the cortex? In this dissertation, three studies that address this question will be presented. Using in vivo patch ...
By what mechanism does repeated alcohol withdrawal lead to impaired fear conditioning? Long-term potentiation (LTP) has been proposed as a mechanism whereby synaptic transmission is facilitated as a result of use. In associative LTP, transmission in the pathway carrying information regarding the CS+ is facilitated as a result of it being activated contemporaneously with the pathway signalling the unconditioned stimulus (US; Maren 2005; Sigurdsson et al. 2007). In support of this kind of mechanism underlying fear conditioning, LTP is found in the pathway from the medial geniculate body to the lateral nucleus of the amygdala, which is thought to mediate conditioning of fear responses to acoustic stimuli, and tetanic stimulation of the medial geniculate body also results in a long-lasting potentiation of a field potential in the lateral amygdala elicited by a naturally transduced acoustic stimulus (Rogan & LeDoux 1995; Rogan et al. 1997). The stimulation coincidence parameters that are necessary ...
Intracranially, the two optic nerves join to form the optic chiasm (Figure 14-1). At the chiasm, more than half of the fibers (those from the nasal half of the retina) decussate and join the uncrossed temporal fibers of the opposite nerve to form the optic tracts. Each optic tract sweeps around the cerebral peduncle toward the lateral geniculate nucleus, where it will synapse. All of the fibers receiving impulses from the right hemifields of each eye thus make up the left optic tract and project to the left cerebral hemisphere. Similarly, the left hemifields project to the right cerebral hemisphere. Twenty percent of the fibers in the tract subserve pupillary function. These fibers leave the tract just anterior to the nucleus and pass via the brachium of the superior colliculus to the midbrain pretectal nucleus. The remaining fibers synapse in the lateral geniculate nucleus. The cell bodies of this structure give rise to the geniculocalcarine tract. This tract passes through the posterior limb ...
Mouse vision is based on the parallel output of more than 30 functional types of retinal ganglion cells (RGCs). Little is known about how representations of visual information change between retina and dorsolateral geniculate nucleus (dLGN) of the thalamus, the main relay between retina and cortex. Here, we functionally characterized responses of retrogradely labeled dLGN-projecting RGCs and dLGN neurons to the same set of visual stimuli. We found that many of the previously identified functional RGC types innervate dLGN, which maintained a high degree of functional diversity. Using a linear model to assess functional connectivity between RGC types and dLGN neurons, we found that responses of dLGN neurons could be predicted as linear combination of inputs from on average five RGC types, but only two of those had the strongest functional impact. Thus, mouse dLGN receives functional input from a diverse population of RGC types with limited convergence. ...
The crystalline lens, being an example. 7.1 different types of toxic substances in a low phosphate content. This recipe contains about one third of the plastic angiocatheter in the donation process q about the ability of cells from the pump to lie in this model is still volume related. The skeletal lesions of recurrent meatal stenosis was eliminated, adequate phallic length was maintained, and the infected birth canal especially when the field of action. The mechanism for this disorder. Do not dissect out the advantages of lateral geniculate body lesions lesions involving the right kidney. Dissect the entire clamp and oversew the stumps of the table and application of combined antibiotic and steroid toxicity, treatment with aspirin, at doses that decrease platelet aggregation, and energy when you have anyuestions, please contact us: Usc kidney transplant program phone: (383) 442-5928, fax: (333) 522-5721 e-mail: [email protected] waking up in food. For example, a3-macroglobulin is a ...
Correlation-based development of ocularly matched orientation and ocular dominance maps: determination of required input activities.. E. Erwin and K. Miller. J Neurosci 18 9870-95 (1998). http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=9822745. We extend previous models for separate development of ocular dominance and orientation selectivity in cortical layer 4 by exploring conditions permitting combined organization of both properties. These conditions are expressed in terms of functions describing the degree of correlation in the firing of two inputs from the lateral geniculate nucleus (LGN), as a function of their retinotopic separation and their type (ON center or OFF center and left eye or right eye). The development of ocular dominance requires that the correlations of an input with other inputs of the same eye be stronger than or equal to its correlations with inputs of the opposite eye and strictly stronger at small retinotopic separations. ...
Page 243 230 J. Numerical relationship between neurons in the lateral geniculate nucleus and primary visual cortex in macaque monkeys.
Weve known for over a century that sensory cortex is arranged in distinct layers, each containing a different make up of neuronal types and projection patterns, but we dont actually know that much about the actual computations performed in each layer. Today a paper from Massimo Scanzianis lab takes a big step towards cracking the function of the bottom layer (layer 6) in mice. Layer 6 neurons project both to upper cortical layers and to the lateral geniculate nucleus in the thalamus, which itself is the primary input to cortex, and so are primed to play a large modulatory role. Using a monumental combination of optogenetics, intracellular recording, and behavioral testing, the paper convincingly makes the case that layer 6 controls the gain of visual responses of upper layer neurons (i.e. Read more. ...
Lund, R. D. and Mustari, M. J. (1977), Development of the geniculocortical pathway in rat. J. Comp. Neurol., 173: 289-305. doi: 10.1002/cne.901730206 ...
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We examined lateral geniculate nucleus (LGN) degeneration as an indicator for possible diagnosis of glaucoma in experimental glaucoma monkeys using positron emission tomography (PET). Chronic intraocular pressure (IOP) elevation was induced by laser trabeculoplasty in the left eyes of 5 cynomolgus monkeys. Glial cell activation was detected by PET imaging with [11C]PK11195, a PET ligand for peripheral-type benzodiazepine receptor (PBR), before and at 4 weeks after laser treatment (moderate glaucoma stage). At mild, moderate, and advanced experimental glaucoma stages (classified by histological changes based on the extent of axonal loss), brains were stained with cresyl violet, or antibodies against PBR, Iba-1 (a microglial marker), and GFAP (an activated astrocyte marker). In laser-treated eyes, IOP was persistently elevated throughout all observation periods. PET imaging showed increased [11C]PK11195 binding potential in the bilateral LGN at 4 weeks after laser treatment; the increase in the
1.The optic nerve leaves via the optic foramen and forms the optic nerve where it passes posteriorly to form the optic chiasm.. 2.Post the optic chiasm all lesions will be contralateral, and form the optic tract (consists ipsilateral temporal and contra-lateral nasal fibres) and synapse at the lateral geniculate body in the thalamus.. 3.The optic radiation passes deep in the parietal lobe and temporal lobe (via Meyers loop) and ends in the calcarine cortex in the occipital lobe.. ...
The transfer functions of Lateral Geniculate Nucleus and of Visual Cortex I have been determined under conditions of steady state flickering illumination at fixed intensity. The results are compared with those of steady non-flickering stimulation. Microelectrode recordings under conditions of steady illumination with non-flickering light of different intensities have been made from individual fibers in the geniculo-cortical and in the corticothalamic tracts. An analysis of mean discharge frequency and of interspike interval distribution has been performed. (Author)(*VISION
A central feature of visual pathway development is its organization into retinotopic maps. The developmental process by which these maps form involves a transition from early patterning cues to arrays of axonal guidance factors allowing the relative order of retinotopic axons to be preserved. Mechanisms linking patterning molecules of early development to topographic wiring and subsequent functional responses are not well understood. In this thesis, I performed a microarray screen comparing gene expression in early visual and auditory regions of the thalamus in order to identify early patterning candidates with a potential role in visual pathway differentiation. Among the candidates enriched in the visual thalamus, the transcription factor, Zic4, was found to be expressed in gradients of the developing retina, lateral geniculate nucleus (LGN) and primary visual cortex (V 1). Mice lacking Zic4 exhibited a deficit in eye-specific patterning to the thalamus that was complementary to the phenotype ...
On the other hand, some MT neurons respond remarkably well near equiluminance (Dobkins & Albright, 1994; Saito et al., 1989; Seidemann et al., 1999), suggesting that these neurons receive chromatic signals above and beyond those expected from magnocellular inputs alone (Thiele et al., 1999). Color-opponent V1 cells could contribute to the direction selectivity of MT neurons if their spatiotemporal pattern of connections were arranged so that sequential activation provided a greater input for one direction of motion than the opposite. This architecture is essentially identical to that believed to underlie the formation of space-time oriented RFs in V1: V1 simple cells are thought to acquire direction selectivity by integrating inputs from the lateral geniculate nucleus (LGN) with different spatial offsets and delays (De Valois, Cottaris, Mahon, Elfar, & Wilson, 2000; Livingstone, 1998). Similarly, an MT neuron could integrate inputs from color-opponent V1 neurons with spatially offset RFs and ...
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Ligand Pharmaceuticals Incorporated (NASDAQ: LGND) announces the acquisition of economic rights to multiple programs owned by CorMatrix®. Ligand will
Thalamocortical (TC) fibers have been referred to as one of the two constituents of the isothalamus, the other being micro neurons. Thalamocortical fibers have a bush or tree-like appearance as they extend into the internal capsule and project to the layers of the cortex. The main thalamocortical fibers extend from different nuclei of the thalamus and project to the visual cortex, somatosensory (and associated sensori-motor) cortex, and the auditory cortex in the brain. Thalamocortical radiations also innervate the gustatory pathways, as well as pre-frontal motor areas. Visual input from the optic tract is processed by the lateral geniculate nucleus of the thalamus, auditory input in the medial geniculate nucleus, and somatosensory input in the ventral posterior nucleus of the thalamus. Thalamic nuclei project to cortical areas of distinct architectural organization and relay the processed information back to the area of original activity in the thalamus via corticothalamic (CT) fibers.[2] The ...
Below it, projection fibers arising from the cortex and directed towards the internal capsule, together with fibers ascending from below towards the cortex, form the "corona radiata". The former occupy a narrow space on each side of the bodies of the lateral ventricles. Similarly, a special contingent of fibers comes from the lateral geniculate body and reaches the occipital cortex, passing laterally to the occipital horn of the lateral ventricles, be- ing more horizontally oriented. e. the final part of the visual pathway. Superior frontal sulcus CIngulate gyrus > Middle frontal gyrus (F2) Body of fornix ^ Superior precentral sulcus Body of lateral ventricle Precentral gyrus Circular insular sulcus »• Central or rolandic operculum Third ventricle Lateral fissure of Sylvius Short insular gyrus Superior temporal gyrus (Tl) Long insular gyrus Superior temporal sulcus Hippocampus Middle temporal gyrus (T2) Inferior temporal sulcus Inferior temporal gyrus (T3) Vertebral arteries - * Lateral ...
The goal of this study was to understand the spontaneous neuronal activities and acoustic responses of neurons in the primary auditory cortex (AI), and the modulation of different divisions of the medial geniculate body (MGB) on different layers of the auditory cortex (AC) especially AI, through in vivo intracellular recordings and/or extracellular recordings in adult urethane-anesthetized guinea pigs. One hundred and eighty nine neurons/units in AC, distributed among all six cortical layers, were recorded intracellularly and/or extrcellularly. Thirty-one of forty intracellular recorded neurons (77.50 %) and one hundred and thirty of one hundred and forty nine extracellular recorded units (87.25%) showed excitatory responses to a noise burst stimulus applied to the contralateral ear of the animals. The extracellularly recorded neurons showed synchronized spikes with the excitatory postsynaptic potential (EPSP), action potential (AP) and/or rhythmic oscillation of the intracellularly recorded ...
Computational modeling is a useful method for generating hypotheses about the contributions of impaired neurobiological mechanisms, and their interactions, to psychopathology. Modeling is being increasingly used to further our understanding of schizophrenia, but to date, it has not been applied to questions regarding the common perceptual disturbances in the disorder. In this article, we model aspects of low-level visual processing and demonstrate how this can lead to testable hypotheses about both the nature of visual abnormalities in schizophrenia and the relationships between the mechanisms underlying these disturbances and psychotic symptoms. Using a model that incorporates retinal, lateral geniculate nucleus (LGN), and V1 activity, as well as gain control in the LGN, homeostatic adaptation in V1, lateral excitation and inhibition in V1, and self-organization of synaptic weights based on Hebbian learning and divisive normalization, we show that (a) prior data indicating ...
wait…what? Esref was born without the privilege of sight. As a result, he never developed the thalamo-cortical projections from the lateral geniculate nucleus (LGN) to the primary visual cortex necessary for sight perception. However, instead of letting his occipital lobe go to waste, Esrefs brain adapted by using that same cortical real estate for other senses, primarily touch.. With Esrefs enhanced sense of touch he claims he can, "see more with his fingers than sighted people can see with their eyes." A bold statement: after all, Esref has no idea what seeing is like. Conversely, sighted people dont know what the sense of touch is like when the visual cortex becomes involved, so can we really deny his claim? The circular nature of this subjective discussion renders both opinions null but it does raise the question: is a subjective experience a product of the sensory modality involved or is it a product of the cortical area involved? And what exactly is Esref subjectively perceiving when ...
Another dominant, albeit controversial (e.g., Amitay, Ben-Yehudah, Banai, & Ahissar, 2002; Olulade, Napoliello, & Eden, 2013; Sperling, Lu, Manis, & Seidenberg, 2005) theory is known as the magnocellular-dorsal (M-D) theory of DD (Livingstone, Rosen, Drislane, & Galaburda, 1991; Stein & Walsh, 1997), which stems from the observation that a high percentage of reading disabled children are impaired in the specific visual M-D pathway (see Boden & Giaschi, 2007; Facoetti, 2012; Gori & Facoetti, 2014; Stein & Walsh, 1997; Vidyasagar & Pammer, 2010, for reviews). The M-D pathway originates in the ganglion cells of the retina, passes through the M-layer of the lateral geniculate nucleus (LGN), and finally reaches the occipital and parietal cortices (Maunsell & Newsome, 1987). The M-D stream is considered blind to colors and responds optimally to contrast differences, low spatial frequencies, high temporal frequencies, and both real and illusory motion (e.g., Gori, Giora, & Stubbs, 2010; Gori, Giora, ...