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The ventral lateral geniculate nucleus (vLGN) is a retinorecipient region of thalamus that contributes to a num-ber of complex visual behaviors. Retinal axons that target vLGN terminate exclusively in the external subdivi-sion (vLGNe), which is also transcriptionally and cytoarchitectonically distinct from the internal subdivision (vLGNi). While recent studies shed light on the cell types and efferent projections of vLGNe and vLGNi, we have a crude understanding of the source and nature of the excitatory inputs driving postsynaptic activity in these regions. Here, we address this by conducting in vitro whole-cell recordings in acutely prepared thalamic slices and using electrical and optical stimulation techniques to examine the postsynaptic excitatory activity evoked by the activation of retinal or cortical layer V input onto neurons in vLGNe and vLGNi. Activation of ret-inal afferents by electrical stimulation of optic tract or optical stimulation of retinal terminals resulted in robust driver-like excitatory activity in vLGNe. Optical activation of corticothalamic terminals from layer V resulted in similar driver-like activity in both vLGNe and vLGNi. Using a dual-color optogenetic approach, we found that many vLGNe neurons received convergent input from these two sources. Both individual pathways displayed similar driver-like properties, with corticothalamic stimulation leading to a stronger form of synaptic depression than retinogeniculate stimulation. We found no evidence of convergence in vLGNi, with neurons only respond-ing to corticothalamic stimulation. These data provide insight into the influence of excitatory inputs to vLGN and reveal that only neurons in vLGNe receive convergent input from both sources.Significance StatementThe ventral lateral geniculate nucleus is traditionally thought of as a thalamic visual recipient structure. However, recent studies reveal its divergent output to a variety of nonvisual subcortical structures helps control an array of light-mediated defensive and mood-related behaviors. Despite this knowledge, we still lack an understanding of where and how inputs to this nucleus drive activity. Here we show that vLGN re-ceives strong, driver-like excitatory input from two sources: the retina and cortical layer V. The external sub-division receives convergent input from both sources, whereas the internal division receives input only from layer V. Such an arrangement has important implications for understanding the functional organization of vLGN and its role in integrating vision with internal behavioral states. Department of Health and Human Services | National Institutes of Health | National Eye Institute [EY-012716, EY-021222] Published version This work was supported by Department of Health and Human Services | National Institutes of Health | National Eye Institute Grants EY-012716 (to W. G.) and EY-021222 (to M.A.F.) .

Subpopulations of neurons and associated neural circuits can be targeted in mice with genetic tools in a highly selective manner for visualization and manipulation. However, there are not well-defined Cre 'driver' lines that target expression of Cre recombinase to thalamocortical neurons. Here were characterize three Cre driver lines for the nuclei of the dorsal thalamus: Oligodendrocyte transcription factor 3 (Olig3)-Cre, histidine decarboxylase (HDC)-Cre, and corticotropin-releasing hormone (CRH)-Cre. We examined the postnatal distribution of Cre expression for each of these lines with the Cre-dependent reporter CAG-tdTomato (Ai9). Cre-dependent expression of tdTomato reveals that Olig3-Cre expresses broadly within thalamus, including thalamocortical neurons and interneurons, while HDC-Cre and CRH-Cre each have unique patterns of expression restricted to thalamocortical neurons within and across the sensory relay nuclei of the dorsal thalamus. Cre expression is present by the time of natural birth in all three lines, underscoring their utility for developmental studies. To demonstrate the utility of these Cre drivers for studying sensory thalamocortical circuitry, we targeted expression of channelrhodopsin-2 to thalamus from the CAG-COP4*H134R/EYFP (Ai32) allele with either HDC-Cre or CRH-Cre. Optogenetic activation of thalamocortical afferents in primary visual cortex was sufficient to measure frequency-dependent depression. Thus, these Cre drivers provide selective Cre-dependent gene expression in thalamus suitable for both anatomical and functional studies. This article is protected by copyright. All rights reserved.

The thalamic reticular nucleus (TRN) is a shell-like structure comprised of GABAergic neurons that surrounds the dorsal thalamus. While playing a key role in modulating thalamocortical interactions, TRN inhibition of thalamic activity is often thought of as having an all-or-none impact. Although TRN neurons have a dynamic firing range, it remains unclear how variable rates of TRN activity gate thalamocortical transmission. To address this, we examined the ultrastructural features and functional synaptic properties of the feedback connections in the mouse thalamus between TRN and the dorsal lateral geniculate nucleus (dLGN), the principal relay of retinal signals to visual cortex. Using electron microscopy to identify TRN input to dLGN, we found that TRN terminals formed synapses with non-GABAergic postsynaptic profiles. Compared with other nonretinal terminals in dLGN, those from TRN were relatively large and tended to contact proximal regions of relay cell dendrites. To evoke TRN activity in dLGN, we adopted an optogenetic approach by expressing ChR2, or a variant (ChIEF) in TRN terminals. Both in vitro and in vivo recordings revealed that repetitive stimulation of TRN terminals led to a frequency-dependent inhibition of dLGN activity, with higher rates of stimulation resulting in increasing levels of membrane hyperpolarization and corresponding decreases in spike firing. This relationship suggests that alterations in TRN activity lead to graded changes in relay cell spike firing. NEW & NOTEWORTHY The thalamic reticular nucleus (TRN) modulates thalamocortical transmission through inhibition. In mouse, TRN terminals in the dorsal lateral geniculate nucleus (dLGN) form synapses with relay neurons but not interneurons. Stimulation of TRN terminals in dLGN leads to a frequency-dependent form of inhibition, with higher rates of stimulation leading to a greater suppression of spike firing. Thus, TRN inhibition appears more dynamic than previously recognized, having a graded rather than an all-or-none impact on thalamocortical transmission.

Retinofugal synapses serve as models for understanding how sensory signals from the periphery are relayed to the brain. Past studies have focused primarily on understanding the postsynaptic glutamatergic receptor subtypes involved in signal transmission, but the mechanisms underlying glutamate release at presynaptic retinal terminals remains largely unknown. Here we explored how different calcium (Ca2+) channel subtypes regulate glutamatergic excitatory synaptic transmission in two principal retinorecipient targets, the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) of the mouse. We used an in vitro slice preparation to record the synaptic responses of dLGN and SC neurons evoked by the electrical stimulation of optic tract (OT) fibers before and during the application of selective Ca2+ channel blockers. We found that synaptic responses to paired or repetitive OT stimulation were highly sensitive to extracellular levels of Ca2+ and to selective antagonists of voltage gated Ca2+ channels, indicating that these channels regulate the presynaptic release of glutamate at retinal synapses in both dLGN and SC. Bath application of selective Ca2+ channel blockers revealed that P/Q-type Ca2+ channels primarily operate to regulate glutamate release at retinal synapses in dLGN, while N-type Ca2+ channels dominate release in the SC.

El presente trabajo de investigación nos ha permitido conocer el nivel del Capital Intelectual de la empresa Estructuras Metálicas JRM SAC, en sus tres componentes Capital Humano, Capital Estructural y Capital Cliente que posee la empresa en base a una serie de indicadores propios del modelo de medición del capital intelectual navegador Skandia. De igual forma, en el estudio se utilizó información tomada del modelo de medición de Imagen Corporativa del Dr. Día Dumont (2015) basada en un cuestionario de preguntas orientadas a determinar la Imagen Comercial, Imagen Estratégica, Imagen Emocional e Imagen Social de la empresa. Asimismo, la investigación estuvo orientada a conocer la relación del Capital Intelectual con la Imagen Corporativa. En el estudio se utilizó como muestra el personal de la empresa agrupada en el nivel operativo, administrativo y comercial, así mismo se midió la percepción de los clientes con los que cuenta la compañía en un periodo determinado En conclusión, los resultados de la investigación muestran que el Capital Intelectual en la empresa Estructuras Metálicas JRM S.A.C es de nivel medio según lo establecido en el modelo navegador SKANDIA, y que existe una relación directa con la Imagen Corporativa según el coeficiente de Correlación de Spearman. De igual forma, en el estudio se identificaron componentes del Capital Intelectual que muestran un mayor desarrollo en comparación de sus otros componentes, lo cual representa una oportunidad de mejora para la compañía en implementar estrategias que permitan potenciar su nivel de Capital Intelectual en su componente Capital Humano, Capital Estructura y Capital Cliente. This research work has allowed us to know the level of Intellectual Capital of the company Estructuras Metálicas JRM SAC, in its three components Human Capital, Structural Capital and Client Capital that the company owns based on a series of indicators of the measurement model of the intellectual capital browser Skandia. In the same way, the study used information taken from the model of Corporate Image measurement of Dr. Día Dumont (2015) based on a questionnaire aimed at determining the Commercial Image, Strategic Image, Emotional Image and Social Image of the company. Likewise, the research was oriented to know the relationship of Intellectual Capital with the Corporate Image. In the study, the company personnel grouped at the operational, administrative and commercial level were used as a sample, as well as the perception of the clients that the company has in a given period. In conclusion, the results of the investigation show that the Intellectual Capital in the company Metallic Structures JRM SAC is of medium level as established in the SKANDIA navigator model, and that there is a direct relationship with the Corporate Image according to the Spearman Correlation coefficient. Similarly, the study identified components of Intellectual Capital that show greater development in comparison to its other components, which represents an opportunity for improvement for the company in implementing strategies that enhance its level of Intellectual Capital in its Capital component Human, Capital Structure and Client Capital. Tesis

Significance Local inhibition, mediated by thalamic interneurons, contributes to the processing of visual information and is essential for vision. However, the mechanisms underlying the development of these interneurons remains unresolved. In this study, we sought to identify mechanisms that contribute to the long-distance migration of these interneurons into the visual thalamus. Our data show that innervation of the visual thalamus by retinal ganglion cells, the output neurons of the retina, is necessary for normal interneuron migration. Surprisingly, axons from these retinal ganglion cells appear to signal through astrocytes to contribute to thalamic interneuron migration. Astrocyte-derived cues may be a general mechanism for guiding interneuron migration throughout the brain., Inhibitory interneurons comprise a fraction of the total neurons in the visual thalamus but are essential for sharpening receptive field properties and improving contrast-gain of retinogeniculate transmission. During early development, these interneurons undergo long-range migration from germinal zones, a process regulated by the innervation of the visual thalamus by retinal ganglion cells. Here, using transcriptomic approaches, we identified a motogenic cue, fibroblast growth factor 15 (FGF15), whose expression in the visual thalamus is regulated by retinal input. Targeted deletion of functional FGF15 in mice led to a reduction in thalamic GABAergic interneurons similar to that observed in the absence of retinal input. This loss may be attributed, at least in part, to misrouting of interneurons into nonvisual thalamic nuclei. Unexpectedly, expression analysis revealed that FGF15 is generated by thalamic astrocytes and not retino-recipient neurons. Thus, these data show that retinal inputs signal through astrocytes to direct the long-range recruitment of interneurons into the visual thalamus.

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 understanding about dLGN comes from studies done in higher mammals, such as the cat and primate, the mouse as a model organism has moved to the forefront as a tractable experimental platform to examine cell type-specific relations. This review highlights our current knowledge about the development, structure, and function of the mouse dLGN.

Receptive field properties of individual visual neurons are dictated by the precise patterns of synaptic connections they receive, including the arrangement of inputs in visual space and features such as polarity (On vs Off). The inputs from the retina to the lateral geniculate nucleus (LGN) in the mouse undergo significant refinement during development. However, it is unknown how this refinement corresponds to the establishment of functional visual response properties. Here we conductedin vivoandin vitrorecordings in the mouse LGN, beginning just after natural eye opening, to determine how receptive fields develop as excitatory and feedforward inhibitory retinal afferents refine. Experiments used both male and female subjects. Forin vivoassessment of receptive fields, we performed multisite extracellular recordings in awake mice. Spatial receptive fields at eye-opening were >2 times larger than in adulthood, and decreased in size over the subsequent week. This topographic refinement was accompanied by other spatial changes, such as a decrease in spot size preference and an increase in surround suppression. Notably, the degree of specificity in terms of On/Off and sustained/transient responses appeared to be established already at eye opening and did not change. We performedin vitrorecordings of the synaptic responses evoked by optic tract stimulation across the same time period. These recordings revealed a pairing of decreased excitatory and increased feedforward inhibitory convergence, providing a potential mechanism to explain the spatial receptive field refinement.SIGNIFICANCE STATEMENTThe development of precise patterns of retinogeniculate connectivity has been a powerful model system for understanding the mechanisms underlying the activity-dependent refinement of sensory systems. Here we link the maturation of spatial receptive field properties in the lateral geniculate nucleus (LGN) to the remodeling of retinal and inhibitory feedforward convergence onto LGN neurons. These findings should thus provide a starting point for testing the cell type-specific plasticity mechanisms that lead to refinement of different excitatory and inhibitory inputs, and for determining the effect of these mechanisms on the establishment of mature receptive fields in the LGN.

The dorsal lateral geniculate nucleus (dLGN) of the mouse is a model system to study the development of thalamic circuitry. Most studies focus on relay neurons of dLGN, yet little is known about the development of the other principal cell type, intrinsic interneurons. Here we examined whether the structure and function of interneurons relies on retinal signaling. We took a loss-of-function approach and crossed GAD67-GFP mice, which express GFP in dLGN interneurons, withmath5nulls (math5−/−), mutants that lack retinal ganglion cells and retinofugal projections.In vitrorecordings and 3-D reconstructions of biocytin-filled interneurons at different postnatal ages showed their development is a multistaged process involving migration, arbor remodeling, and synapse formation. Arbor remodeling begins during the second postnatal week, after migration to and dispersion within dLGN is complete. This phase includes a period of exuberant branching where arbors grow in number, complexity, and field size. Such growth is followed by branch pruning and stabilization, as interneurons adopt a bipolar architecture. The absence of retinal signaling disrupts this process. The math5−/−interneurons fail to branch and prune, and instead maintain a simple, sparse architecture. To test how such defects influence connectivity with dLGN relay neurons, we used DHPG [(RS)-3,5-dihydroxyphenylglycine], the mGluR1,5agonist that targets F2 terminals. This led to substantial increases in IPSC activity among WT relay neurons but had little impact in math5−/−mice. Together, these data suggest that retinal signaling is needed to support the arbor elaboration and synaptic connectivity of dLGN interneurons.SIGNIFICANCE STATEMENTPresently, our understanding about the development of the dorsal lateral geniculate nucleus is limited to circuits involving excitatory thalamocortical relay neurons. Here we show that the other principal cell type, intrinsic interneurons, has a multistaged developmental plan that relies on retinal innervation. These findings indicate that signaling from the periphery guides the maturation of interneurons and the establishment of inhibitory thalamic circuits.

El objetivo de la presente investigación fue demostrar que mediante el desarrollo de las competencias laborales del personal operativo en una empresa del Sector Metal mecánico permite contribuir con la implementación de un Sistema de Gestión de Calidad ISO 9001:2015. Las competencias laborales es una combinación de conocimientos, actitudes y habilidades. Para probar las hipótesis, se ha desarrollado una investigación no experimental, en la empresa Estanterías Metálicas JRM S.A.C, ubicada en el distrito de San Juan de Lurigancho, Lima, Perú. Se trabajó con los supervisores de producción y el personal operativo de las diversas áreas de productiva de la organización para la recopilación de información mediante el instrumento diseñado para medir las competencias laborales en relación a la gestión de calidad ISO 9001:2015.

Retinofugal synapses serve as models for understanding how sensory signals from the periphery are relayed to the brain. Past studies have focused primarily on understanding the postsynaptic glutamatergic receptor subtypes involved in signal transmission, but the mechanisms underlying glutamate release at presynaptic retinal terminals remains largely unknown. Here we explored how different calcium (Ca2+) channel subtypes regulate glutamatergic excitatory synaptic transmission in two principal retinorecipient targets, the dorsal lateral geniculate nucleus (dLGN) and superior colliculus (SC) of the mouse. We used anin vitroslice preparation to record the synaptic responses of dLGN and SC neurons evoked by the electrical stimulation of optic tract (OT) fibers before and during the application of selective Ca2+channel blockers. We found that synaptic responses to paired or repetitive OT stimulation were highly sensitive to extracellular levels of Ca2+and to selective antagonists of voltage gated Ca2+channels, indicating that these channels regulate the presynaptic release of glutamate at retinal synapses in both dLGN and SC. Bath application of selective Ca2+channel blockers revealed that P/Q-type Ca2+channels primarily operate to regulate glutamate release at retinal synapses in dLGN, while N-type Ca2+channels dominate release in the SC.

Despite the widespread adoption of uniportal video-assisted thoracoscopic surgery (UniVATS) for lung cancer, some procedures are still rarely performed with this approach. A minimally invasive approach is seldom selected to perform a pneumonectomy for a number of different reasons, usually involving the experience of the surgeon and the specific characteristics of cases requiring pneumonectomy as a treatment. Some surgeons believe that because of the complexity of such cases involving large tumors and usually some sort of hilum compromise, a minimally invasive technique cannot be safely performed. Safety involved in performing this procedure is more related to the surgeon experience in the approach than to the procedure itself, and it mostly depends on prior exposure to complex uniportal cases. In a time when several groups around the world are performing bronchovascular reconstructions, carinal resections by UniVATS the question should not be if is possible to perform UniVATS pneumonectomy, but what are the factors and considerations the surgeon must take into account in order to perform these cases. This review aims to provide an update on current status of uniportal VATS pneumonectomy and to provide guidance for surgeons who face this sort of cases.

The thalamic reticular nucleus (TRN), a shell-like structure comprised of GABAergic neurons, gates signal transmission between thalamus and cortex. While TRN is innervated by axon collaterals of thalamocortical and corticothalamic neurons, other ascending projections modulate activity during different behavioral states such as attention, arousal, and sleep-wake cycles. One of the largest arise from cholinergic neurons of the basal forebrain and brainstem. Despite its integral role, little is known about how or when cholinergic innervation and synapse formation occurs. We utilized genetically modified mice, which selectively express fluorescent protein and/or channelrhodopsin-2 in cholinergic neurons, to visualize and stimulate cholinergic afferents in the developing TRN. Cholinergic innervation of TRN follows a ventral-to-dorsal progression, with non-visual sensory sectors receiving input during week 1, and the visual sector during week 2. By week 3, the density of cholinergic fibers increases throughout TRN and forms a reticular profile. Functional patterns of connectivity between cholinergic fibers and TRN neurons progress in a similar manner, with weak excitatory nicotinic responses appearing in non-visual sectors near the end of week 1. By week 2, excitatory responses become more prevalent and arise in the visual sector. Between weeks 3–4, inhibitory muscarinic responses emerge, and responses become biphasic, exhibiting a fast excitatory, and a long-lasting inhibitory component. Overall, the development of cholinergic projections in TRN follows a similar plan as the rest of sensory thalamus, with innervation of non-visual structures preceding visual ones, and well after the establishment of circuits conveying sensory information from the periphery to the cortex.

The uniportal approach for major pulmonary resections began in 2010, with the first case being reported by D Gonzalez-Rivas and colleagues in La Coruna, Spain. Since then, in different countries, thoracic surgeons had been performing hundreds of cases, with more advanced and complex procedures. Nowadays, there are reports of uniportal tracheal resection and reconstruction, carinal resection, bronchoplastic procedures, lobectomies with en bloc chest wall excision, and vascular reconstruction with optimal outcomes. The development of technologies and the potential benefits of a direct view, anatomic instrumentation, better cosmesis, and, potentially, less postoperative pain have led uniportal video-assisted thoracic surgery to grow exponentially worldwide.

The link between neural activity and the refinement of projections from retina to the dorsal lateral geniculate nucleus (dLGN) of thalamus is based largely on studies that disrupt presynaptic retinogeniculate activity. Postsynaptic mechanisms responsible for implementing the activity-dependent remodeling in dLGN remain unknown. We tested whether L-type Ca2+channel activity in the form of synaptically evoked plateau potentials in dLGN cells is needed for remodeling by using a mutant mouse that lacks the ancillary β3subunit and, as a consequence, has highly reduced L-type channel expression and attenuated L-type Ca2+currents. In the dLGNs of β3-null mice, glutamatergic postsynaptic activity evoked by optic tract stimulation was normal, but plateau potentials were rarely observed. The few plateaus that were evoked required high rates of retinal stimulation, but were still greatly attenuated compared with those recorded in age-matched wild-type mice. While β3-null mice exhibit normal stage II and III retinal waves, their retinogeniculate projections fail to segregate properly and dLGN cells show a high degree of retinal convergence even at late postnatal ages. These structural and functional defects were also accompanied by a reduction in CREB phosphorylation, a signaling event that has been shown to be essential for retinogeniculate axon segregation. Thus, postsynaptic L-type Ca2+activity plays an important role in mediating the refinement of the retinogeniculate pathway.

Background The dorsal lateral geniculate nucleus (dLGN) of the mouse has become a model system for understanding thalamic circuit assembly. While the development of retinal projections to dLGN has been a topic of extensive inquiry, how and when nonretinal projections innervate this nucleus remains largely unexplored. In this study, we examined the development of a major nonretinal projection to dLGN, the ascending input arising from cholinergic neurons of the brainstem. To visualize these projections, we used a transgenic mouse line that expresses red fluorescent protein exclusively in cholinergic neurons. To assess whether retinal input regulates the timing and pattern of cholinergic innervation of dLGN, we utilized the math5-null (math5 −/−) mouse, which lacks retinofugal projections due to a failure of retinal ganglion cell differentiation. Results Cholinergic brainstem innervation of dLGN began at the end of the first postnatal week, increased steadily with age, and reached an adult-like pattern by the end of the first postnatal month. The absence of retinal input led to a disruption in the trajectory, rate, and pattern of cholinergic innervation of dLGN. Anatomical tracing experiments reveal these disruptions were linked to cholinergic projections from parabigeminal nucleus, which normally traverse and reach dLGN through the optic tract. Conclusions The late postnatal arrival of cholinergic projections to dLGN and their regulation by retinal signaling provides additional support for the existence of a conserved developmental plan whereby retinal input regulates the timing and sequencing of nonretinal projections to dLGN.

The dorsal lateral geniculate nucleus (dLGN) of the thalamus is the principal conduit for visual information from retina to visual cortex. Viewed initially as a simple relay, recent studies in the mouse reveal far greater complexity in the way input from the retina is combined, transmitted, and processed in dLGN. Here we consider the structural and functional organization of the mouse retinogeniculate pathway by examining the patterns of retinal projections to dLGN and how they converge onto thalamocortical neurons to shape the flow of visual information to visual cortex.

The pulvinar nucleus is a large thalamic structure involved in the integration of visual and motor signals. The pulvinar forms extensive connections with striate and extrastriate cortical areas, but the impact of these connections on cortical circuits has not previously been directly tested. Using a variety of anatomical, optogenetic, andin vitrophysiological techniques in male and female mice, we show that pulvinocortical terminals are densely distributed in the extrastriate cortex where they form synaptic connections with spines and small-diameter dendrites. Optogenetic activation of these synapsesin vitroevoked large excitatory postsynaptic responses in the majority of pyramidal cells, spiny stellate cells, and interneurons within the extrastriate cortex. However, specificity in pulvinar targeting was revealed when recordings were targeted to projection neuron subtypes. The neurons most responsive to pulvinar input were those that project to the striatum and amygdala (76% responsive) or V1 (55%), whereas neurons that project to the superior colliculus were rarely responsive (6%). Because the pulvinar also projects directly to the striatum and amygdala, these results establish the pulvinar nucleus as a hub linking the visual cortex with subcortical regions involved in the initiation and control of movement. We suggest that these circuits may be particularly important for coordinating body movements and visual perception.SIGNIFICANCE STATEMENTWe found that the pulvinar nucleus can strongly influence extrastriate cortical circuits and exerts a particularly strong impact on the activity of extrastriate neurons that project to the striatum and amygdala. Our results suggest that the conventional hierarchical view of visual cortical processing may not apply to the mouse visual cortex. Instead, our results establish the pulvinar nucleus as a hub linking the visual cortex with subcortical regions involved in the initiation and control of movement, and predict that the execution of visually guided movements relies on this network.

Las organizaciones que desean ser cada vez más competitivas requieren desarrollar las competencias del personal, optimizando su potencial para lograr altos niveles de competitividad y satisfacción. Los modelos tradicionales definen perfiles de puestos sin contemplar un análisis profundo sobre el desarrollo de competencias del personal. La investigación presenta dos variables: competencia laboral y gestión de calidad ISO 9001:2015 y está orientada a determinar la relación entre ambas, para luego determinar que competencias requieren ser desarrolladas mediante planes de acción. Para la obtención de información, procesamiento de datos y análisis de resultados se diseñó un cuestionario, validado por expertos, aplicable a la naturaleza de la empresa y sea entendible por el personal operativo durante la investigación. Asimismo, la investigación se llevó a cabo en una empresa peruana del sector metalmecánico, ubicado en el distritito de San Juan de Lurigancho. Se utilizó como muestra el personal operativo representado por cada una de las áreas de producción, se aplicaron una variedad de técnicas científicas de trabajo de campo, principalmente guías de observación, para demostrar la hipótesis planteada y posteriormente generar una propuesta a desarrollar. En suma, el resultado de la investigación muestra que el instrumento diseñado para medir las variables de estudio es aceptable con significancia moderada. En base a la investigación presentada, se identificó que hay áreas operativas que cuentan con personal con competencias más desarrolladas que otras en sus puestos de trabajo, y otras que requieren reforzamiento referente a los aspectos técnicos de la operación y requisitos significantes de un Sistema de Gestión de Calidad ISO. Finalmente, se muestran las conclusiones y recomendaciones de mejoras para contrarrestar los puntos débiles identificados y que contribuya a mejorar el desempeño de los procesos operativos en la organización.

Neural circuit formation demands precise timing of innervation by different classes of axons. However, the mechanisms underlying such activity remain largely unknown. In the dorsal lateral geniculate nucleus (dLGN), axons from the retina and visual cortex innervate thalamic relay neurons in a highly coordinated manner, with those from the cortex arriving well after those from retina. The differential timing of retino- and corticogeniculate innervation is not a coincidence but is orchestrated by retinal inputs. Here, we identified a chondroitin sulfate proteoglycan (CSPG) that regulates the timing of corticogeniculate innervation. Aggrecan, a repulsive CSPG, is enriched in neonatal dLGN and inhibits cortical axons from prematurely entering the dLGN. Postnatal loss of aggrecan from dLGN coincides with upregulation of aggrecanase expression in the dLGN and corticogeniculate innervation and, it is important to note, is regulated by retinal inputs. Taken together, these studies reveal a molecular mechanism through which one class of axons coordinates the temporal targeting of another class of axons. National Institutes of Health NIH: EY012716 NIH: EY021222

Purpose The prevalence of minimally invasive lung cancer surgery using video-assisted thoracic surgery (VATS) has increased dramatically over the past decade, yet recent studies have suggested that the lymph node evaluation during VATS lobectomy is inadequate. We hypothesized that the minimally invasive approach to lobectomy for stage I lung cancer resulted in a longitudinal outcome that was not inferior to thoracotomy. Patients and Methods Patients65 years of age who had undergone lobectomy for stage I lung cancer between 2002 and 2013 were analyzed within the Society of Thoracic Surgeons General Thoracic Surgery Database, which had been linked to Medicare data, as part of a retrospective-cohort, noninferiority study. Results A total of 10,597 patients with clinical stage I lung cancer who underwent lobectomy were evaluated (4,448 patients underwent thoracotomy, and 6,149 underwent VATS). VATS patients had a more favorable distribution of all health-related variables, including pulmonary function (59% of VATS patients had intact spirometry v 51% of thoracotomy patients; P.001). Cox proportional hazards models were performed over two eras to account for an evolving practice standard. The mortality risk associated with the VATS approach was not greater than thoracotomy in either the earlier era (2002 to 2008; hazard ratio, 0.97; 95% CI, 0.87 to 1.09; P = .62) or the more recent era (2009 to 2013; hazard ratio, 0.84; 95% CI, 0.75 to 0.93; P.001). Kaplan-Meier survival estimates of 2,901 propensity-matched VATS-thoracotomy pairs demonstrated that the 4-year survival associated with VATS (68.6%) was modestly superior to thoracotomy (64.8%; P = .003). The analyses detailed above were replicated in a separate cohort of pathologic stage I patients with similar findings. Conclusion The long-term efficacy of lobectomy for stage I lung cancer performed using the VATS approach by board-certified thoracic surgeons does not seem to be inferior to that of thoracotomy.

Neurons in layer VI of visual cortex represent one of the largest sources of nonretinal input to the dorsal lateral geniculate nucleus (dLGN) and play a major role in modulating the gain of thalamic signal transmission. However, little is known about how and when these descending projections arrive and make functional connections with dLGN cells. Here we used a transgenic mouse to visualize corticogeniculate projections to examine the timing of cortical innervation in dLGN. Corticogeniculate innervation occurred at postnatal ages and was delayed compared with the arrival of retinal afferents. Cortical fibers began to enter dLGN at postnatal day 3 (P3) to P4, a time when retinogeniculate innervation is complete. However, cortical projections did not fully innervate dLGN until eye opening (P12), well after the time when retinal inputs from the two eyes segregate to form nonoverlapping eye-specific domains. In vitro thalamic slice recordings revealed that newly arriving cortical axons form functional connections with dLGN cells. However, adult-like responses that exhibited paired pulse facilitation did not fully emerge until 2 weeks of age. Finally, surgical or genetic elimination of retinal input greatly accelerated the rate of corticogeniculate innervation, with axons invading between P2 and P3 and fully innervating dLGN by P8 to P10. However, recordings in genetically deafferented mice showed that corticogeniculate synapses continued to mature at the same rate as controls. These studies suggest that retinal and cortical innervation of dLGN is highly coordinated and that input from retina plays an important role in regulating the rate of corticogeniculate innervation.

Background Human immunodeficiency virus (HIV) associated neurocognitive disorders (HAND), including memory dysfunction, continue to be a major clinical manifestation of HIV type-1 infection. Viral proteins released by infected glia are thought to be the principal triggers of inflammation and bystander neuronal injury and death, thereby driving key symptomatology of HAND. Methods We used a glial fibrillary acidic protein-driven, doxycycline-inducible HIV type-1 transactivator of transcription (Tat) transgenic mouse model and examined structure-function relationships in hippocampal pyramidal cornu ammonis 1 (CA1) neurons using morphologic, electrophysiological (long-term potentiation [LTP]), and behavioral (Morris water maze, fear-conditioning) approaches. Results Tat induction caused a variety of different inclusions in astrocytes characteristic of lysosomes, autophagic vacuoles, and lamellar bodies, which were typically present within distal cytoplasmic processes. In pyramidal CA1 neurons, Tat induction reduced the number of apical dendritic spines, while disrupting the distribution of synaptic proteins (synaptotagmin 2 and gephyrin) associated with inhibitory transmission but with minimal dendritic pathology and no evidence of pyramidal neuron death. Electrophysiological assessment of excitatory postsynaptic field potential at Schaffer collateral/commissural fiber-CA1 synapses showed near total suppression of LTP in mice expressing Tat. The loss in LTP coincided with disruptions in learning and memory. Conclusions Tat expression in the brain results in profound functional changes in synaptic physiology and in behavior that are accompanied by only modest structural changes and minimal pathology. Tat likely contributes to HAND by causing molecular changes that disrupt synaptic organization, with inhibitory presynaptic terminals containing synaptotagmin 2 appearing especially vulnerable.

Video-assisted thoracoscopic surgery (VATS) has experience an exponential growth in lung anatomic resections. Since its beginnings in early 90s with the conventional multiport VATS to the more recent uniportal approach, a continuous search for a less invasive procedure has fueled the development of minimally invasive thoracic surgery. In this sense, subxiphoid uniportal VATS has surge as a uniportal option that avoids damage to the intercostal nerve created in a transthoracic approach. In order for this technique to become as an acceptable choice for lung cancer, oncologic principles must be respected, including a feasible and safe mediastinal lymphadenectomy. Although technically more difficult than other VATS approaches, a complete lymphadenectomy is possible in the hands of expert VATS surgeons through a subxiphoid approach.

The uniportal approach for major pulmonary resections began in 2010 with the first case being performed by Gonzalez-Rivas and colleagues in La Coruna. Since then a number of teams around the world had being performing hundreds of cases, applying it to more advance and complex cases recently. The technique has been reported to be feasible and reliable with similar results to that obtained in early stage lung cancer lobectomies. The case presented in this article is an example of an extreme condition: very obese patient, strong adhesions, fused lower lobe to the diaphragm and enlarged inflammatory adenopathies that made the procedure very technically challenging. In addition, the surgery was performed during a live surgery event and it was broadcasted to an auditorium. However, the case was successfully completed through a uniportal VATS approach with no complications.

Background: Subxiphoid uniportal video-assisted thoracic surgery (SVATS) for major lung resections is a new approach. Clinical evidence is lacking. The aim of this article is to describe the learning curve of the 200 selected patients who underwent uniportal subxiphoid lobectomy or segmentectomy by subxiphoid midline incision, and with the lessons learned from this early experience in SVATS and from the experience with transthoracic uniportal VATS we sought to compile “tips and tricks” for managing the multiple intraoperative technical difficulties that can arise during the SVATS and help to set the recommendations for a SVATS program. Methods: We describe the learning curve of the first 200 selected patients who underwent uniportal subxiphoid lobectomy or segmentectomy by subxiphoid midline incision From September 2014 with early-stage non-small cell lung carcinoma (NSCLC) and benign disease. We examine the rate of conversion and the operating time comparing group one (first 100 cases) with group two (subsequent 100 cases). Results: Of the 200 consecutive selected cases (72 males, 128 females) with a mean age of 57.4±9 years, underwent either uniportal subxiphoid lobectomy or segmentectomy 136 were lobectomies and 64 were segmental resections The mean operating time was 170±45 mins; the average and after the case 86 the rate of the operating time appears to be similar. The conversion rate decrease from 13% in group one to 8% in group two. Conclusions: There is a gradual reduction in the operating time and rate conversion with increasing experience. Lessons from our initial experience in the learning curve period in SVATS helps to create this trouble shooting guide that offers “tips and tricks” to both avoid and manage numerous intra-operative technical difficulties that commonly arise during the SVATS initial experience.

During the last decade, there have been important developments in new minimally invasive surgical techniques for major pulmonary resections (1). Advances in anesthesiology include a lack of general anesthesia in thoracic operations, by maintaining spontaneous ventilation, and minimal sedation of patients. The choice of a single-incision technique combined with the lack of general anesthesia further minimize the invasiveness of the procedure (2). Moreover, a ‘tubeless’ concept can be perfectly applied to these procedures. This involves the complete absence of a tracheal tube or even laryngeal mask, central line, urinary catheter or epidural. We present a video showing three cases of non-intubated (tubeless) uniportal video-assisted thoracoscopic surgery (VATS) major pulmonary resections (Video 1). Video 1 Non-intubated (tubeless) uniportal video-assisted thoracoscopic lobectomy.

Surgical treatment of lung cancer has evolved to a minimally invasive approach and currently is recognized as an acceptable treatment for resectable non-small cell lung cancer (NSCLC). As the volume and complexity of cases has increased technical difficulties had arisen. Hilar and sublobar lymph nodes can represent a challenge for video-assisted thoracoscopic surgery (VATS) surgeons in order to complete a safe dissection of vascular and bronchial structures without complications or conversion. It is not unusual the patients with smoking history or benign infections in the past present with enlarged calcified nodes that are fused to the hilum, fissure and specially the bronchus which can lead to an accident during the procedure if the surgeon has no experience handling this issue. As the amount of surgeons carrying out VATS lobectomies grows it is very important for them to know what to do in this specific case so the completion of the procedure can be achieved safely.The coordination between the surgeon and the assistant is very important in order to carry out the procedure without discomfort positions and good visualization, the use of energy devices in expert hands can help considerably during the dissection of lymph nodes in the hilum and fissure reducing the bleeding, which provides a clean operative field. It is a necessary maneuver during the dissection to find the correct adventitial plane between the lymph node and the structure before passing it.The videos in this article show the different maneuvers a VATS surgeon can implement when facing enlarged fussed lymph nodes in the hilum, fissure or mediastinum. Improving exposure, opening the fissure, using energy and carrying out the dissection through the correct plane are keys to complete the procedure successfully.With growing experience in uniportal VATS and advances in surgical technology, enlarged or fussed lymph nodes are no longer a contraindication to complete a VATS lobectomy, experience VATS surgeons have a repertory of options in order to perform a safe and effective dissection.

Objectives Uniportal subxiphoid video-assisted thoracoscopic (SVATS) surgery for major lung resections is a new approach, but clinical evidence is lacking. The aim of this study was to examine our experience with the use of the uniportal subxiphoid approach in video-assisted thoracoscopic (VATS) major lung resections and lymph node dissections. Methods From October 2014 to August 2015, 153 patients with early-stage non-small-cell lung carcinoma (NSCLC) and benign disease underwent uniportal subxiphoid VATS major lung resections. Patients were placed in a lateral position with 60-70° inclination, and a 4- to 5-cm midline median or transverse incision was made below the sternocostal triangle. A 10-mm 30° video camera and VATS instruments were used through the same single incision. Perioperative variables and outcomes were collected prospectively and analysed retrospectively. Results Of the 153 patients who underwent surgery with the uniportal subxiphoid VATS approach, 105 had lobectomies and 48 had segmental resections; 135 cases of lung cancer and 18 cases of benign pulmonary disease were noted. Right upper lobectomy was the most common procedure (51%), and left upper lobectomy was the most time-consuming procedure (190 ± 21 min). The mean operating time was 166.9 ± 12.6 min; the average volume of blood loss was 127.5 ± 27.6 ml. In patients with lung cancer, the mean total number of lymph node stations explored was 3.4 ± 0.8. The duration of chest drain use was 2.6 ± 0.2 days. The length of hospital stay was 4.3 ± 0.4 days. Perioperative arrhythmia was the most common complication (13% of cases). Prolonged air leak was the cause of prolonged hospital stay. Five cases were converted to conventional VATS due to technical difficulties, and eight cases were converted to thoracotomy due to major bleeding. Postoperative 30-day mortality was zero and there were no re-admissions. All cases had a R0 complete cancer resection on histology. Conclusions Uniportal subxiphoid VATS lobectomy/segmentectomy is a feasible and safe procedure for early-stage lung cancer and benign disease.

A fundamental feature of the mammalian visual system is the presence of separate channels that work in parallel to efficiently extract and analyze specific elements of a visual scene. Despite the extensive use of the mouse as a model system, it is not clear whether such parallel organization extends beyond the retina to subcortical structures, such as the dorsal lateral geniculate (dLGN) of thalamus. To begin to address this, we examined the morphology of biocytin-filled relay cells recorded in dLGN of mice. Based on a quantitative assessment of their dendritic architecture, we found that even at early postnatal ages relay cells could be readily classified as X-like (biconical), Y-like (symmetrical), or W-like (hemispheric) and that each cell type was regionally specified in dLGN. X-like cells were confined primarily to the monocular ventral region of dLGN. Y-like cells occupied a central core that also contained ipsilateral eye projections, whereas W-like cells were found along the perimeter of dLGN. Similar to cat, Y-like cells were more prevalent than X- and W-like cells, and X-like cells tended to be smaller than other cell types. However, the dendritic fields of X- and W-like cells did not exhibit an orientation bias with respect to optic tract or boundaries of dLGN. Although we found clear morphological differences among relay cells, an analysis of their electrophysiological properties did not reveal any additional distinguishing characteristics. Overall, these data coupled with recent observations in the retina suggest that the mouse has many of the hallmark features of a system-wide parallel organization.

In developing cells of the mouse dorsal lateral geniculate nucleus (dLGN), synaptic responses evoked by optic tract (OT) stimulation give rise to long-lasting, high-amplitude depolarizations known as plateau potentials. These events are mediated by L-type Ca2+ channels and occur during early postnatal life, a time when retinogeniculate connections are remodelling. To better understand the relationship between L-type activity and dLGN development we used an in vitro thalamic slice preparation which preserves the retinal connections and intrinsic circuitry in dLGN and examined how synaptic responses evoked by OT stimulation lead to the activation of plateau potentials. By varying the strength and temporal frequency of OT stimulation we identified at least three factors that contribute to the developmental regulation of plateau activity: the degree of retinal convergence, the temporal pattern of retinal stimulation and the emergence of feed-forward inhibition. Before natural eye opening (postnatal day 14), the excitatory synaptic responses of relay cells receiving multiple retinal inputs summated in both the spatial and temporal domains to produce depolarizations sufficient to activate L-type activity. After eye opening, when inhibitory responses are fully developed, plateau activity was rarely evoked even with high temporal rates of OT stimulation. When the bulk of this inhibition was blocked by bath application of bicuculline, the incidence of plateau activity increased significantly. We also made use of a transgenic mouse that lacks the β3 subunit of the L-type Ca2+ channel. These mutants have far fewer membrane-bound Ca2+ channels and attenuated L-type activity. In β3 nulls, L-type plateau activity was rarely observed even at young ages when plateau activity prevails. Thus, in addition to the changing patterns of synaptic connectivity and retinal activity, the expression of L-type Ca2+ channels is a requisite component in the manifestation of plateau activity.

Development of visual system circuitry requires the formation of precise synaptic connections between neurons in the retina and brain. For example, axons from retinal ganglion cells (RGCs) form synapses onto neurons within subnuclei of the lateral geniculate nucleus (LGN) [i.e., the dorsal LGN (dLGN), ventral LGN (vLGN), and intergeniculate leaflet (IGL)]. Distinct classes of RGCs project to these subnuclei: the dLGN is innervated by image-forming RGCs, whereas the vLGN and IGL are innervated by non-image-forming RGCs. To explore potential mechanisms regulating class-specific LGN targeting, we sought to identify differentially expressed targeting molecules in these LGN subnuclei. One candidate targeting molecule enriched in the vLGN and IGL during retinogeniculate circuit formation was the extracellular matrix molecule reelin. Anterograde labeling of RGC axons in mutant mice lacking functional reelin (relnrl/rl) revealed reduced patterns of vLGN and IGL innervation and misrouted RGC axons in adjacent non-retino-recipient thalamic nuclei. Using genetic reporter mice, we further demonstrated that mistargeted axons were from non-image-forming, intrinsically photosensitive RGCs (ipRGCs). In contrast to mistargeted ipRGC axons, axons arising from image-forming RGCs and layer VI cortical neurons correctly targeted the dLGN inrelnrl/rlmutants. Together, these data reveal that reelin is essential for the targeting of LGN subnuclei by functionally distinct classes of RGCs.

The purpose of the present study was to determine whether retinal activity can support long-term changes in synaptic strength in the developing dorsal lateral geniculate nucleus (LGN) of thalamus. To test for this we made use of a rodent in vitro explant preparation in which retinal afferents and the intrinsic circuitry of the LGN remain intact. We repetitively stimulated the optic tract with a tetanus protocol that approximated the temporal features of spontaneous retinal waves. We found the amplitude of extracellular field potentials evoked by retinal stimulation changed significantly after tetanus and that the polarity of these alterations was related to postnatal age. At a time when substantial pruning of retinal connections occurs (postnatal day 1 [P1] to P14), high-frequency stimulation led to an immediate and long-term depression (LTD). However, at times when pruning wanes and adultlike patterns of connectivity are stabilizing (P16 to P30), the identical form of stimulation produced a modest form of potentiation (long-term potentiation [LTP]). The LTD was unaffected by the bath application of γ-aminobutyric acid type A and N-methyl-d-aspartate receptor antagonists. However, both LTD and LTP were blocked by L-type Ca2+-channel antagonists. Thus the Ca2+ influx associated with L-type channel activation mediates the induction of synaptic plasticity and may signal the pruning and subsequent stabilization of developing retinogeniculate connections.

The dorsal lateral geniculate nucleus (dLGN) of the thalamus has served as an important model for understanding many aspects of visual system development including early pathfinding, synaptogenesis, visual map formation, and the activity-dependent refinement of synaptic connections. In recent years the mouse has become a major experimental platform for detailing key elements involved in these events. Despite the abundance of studies done in the mouse, little is known about the underlying synaptic organization of the developing dLGN. To date, studies have focused largely on the development of retinogeniculate connections (Guido, 2008). Initially, dLGN cells are binocularly innervated and receive as many as a dozen or so separate retinal inputs. By natural eye opening (P12–P14) many of these inputs have been eliminated so that dLGN cells receive monocular innervation from just one or a few retinal ganglion cells. During this pruning phase, the remaining retinogeniculate synapses experience a several fold increase in strength (Chen and Regehr, 2000). Little is known regarding the ultrastructural changes underlying these events. In adult tissue, retinal terminals in the dLGN have been well studied and are quite distinct (Szentagothai et al., 1966; Guillery, 1969; Guillery, 1971; Robson and Mason, 1979; Hamos et al., 1987). They are known as RLP profiles because of their round shaped vesicles, large size, and pale mitochondria. Indeed, retinal terminals are the largest terminals in the dLGN, and each bouton forms multiple synaptic contacts (Rafols and Valverde, 1973; Rapisardi and Miles, 1984; Wilson et al., 1984). Whether these features are apparent at early ages, and how the remodeling process takes shape at the ultrastructural level, remain unexplored. Adult retinogeniculate terminals also contact dendritic terminals (F2 profiles), which have been identified as originating from interneurons (Famiglietti, 1970; Famiglietti and Peters, 1972; Rafols and Valverde, 1973; Lieberman and Webster, 1974; Hamos et al., 1985) that utilize γ-aminobutyric acid (GABA) as a neurotransmitter (Montero and Singer, 1985; Montero, 1991; Fitzpatrick et al., 1984). Unique “triadic” arrangements are formed when a single retinal terminal is pre-synaptic to both a relay cell dendrite and an F2 profile, which are themselves connected by a synapse. These arrangements often occur within a glomerulus, a complex zone of multiple synapses encased by a glial sheath (Sherman, 2004). In other species, approximately 20% of the retinogeniculate synapses are formed with F2 profiles and the remainder with relay cell dendrites (Wilson and Hendrickson, 1981; Erisir et al., 1998; Van Horn et al., 2000; Datskovskaia et al., 2001; Li et al., 2003). However, although triadic arrangements have been identified in the adult mouse dLGN (Rafols and Valverde, 1973), it is not clear how prevalent these synapses are, because mice have far fewer intrinsic interneurons than higher mammals (Arcelli et al., 1997). It is also not clear when they first appear during development because the maturation of some inhibitory synapses in the rodent thalamus is delayed until postnatal ages (DeBiasi et al., 1997; Ziburkus et al., 2003). Finally, although retinal inputs provide the primary excitatory drive for dLGN cells, most of the synaptic connections in the dLGN arise from nonretinal sources (Sherman and Guillery, 2002). In the adult dLGN, the cortex and brainstem provide glutamatergic and cholinergic inputs, respectively (Erisir et al., 1997a,b), in the form of small profiles with densely packed round vesicles and dark mitochondria (RSD profiles). Additional GABAergic inputs arise from the thalamic reticular nucleus (TRN), pretectum, and interneuron axons in the form of medium-sized terminals that contain densely packed vesicles (F1 profiles), distinguishing them from the more loosely packed vesicles contained within F2 profiles (Ohara et al., 1980; Montero and Scott, 1981; Fitzpatrick et al., 1984; Wilson et al., 1984; Hamos et al., 1985; Montero and Singer, 1985; Cucchiaro et al., 1991a,b; Arcelli et al., 1997; Wang et al., 2001; Wang et al., 2002; Li et al., 2003). However, little if anything is known about how, where, and when these connections emerge or coordinate with the refinement of retinogeniculate connections. To address these questions, we explored the synaptic organization of the developing mouse dLGN in the common pigmented C57/BL6 strain, first by recording the synaptic responses evoked by electrical stimulation of optic tract axons, and second by examining the ultrastructure of identified synapses. To aid in the characterization of inhibitory elements, we also made use of postembedding immunocytochemical staining for GABA.

Much of our present understanding about the mechanisms contributing to the activity-dependent refinement of sensory connections comes from experiments done in the retinogeniculate pathway. In recent years the mouse has emerged as a model system of study. This review outlines the major changes in connectivity that occur in this species and a potential mechanism that can account for such remodelling. During early postnatal life when spontaneous activity of retinal ganglion cells sweeps across the retina in waves, retinal projections from the two eyes to the dorsal lateral geniculate nucleus (LGN) segregate to form non-overlapping eye-specific domains. There is a loss of binocular innervation, a pruning of excitatory inputs from a dozen or more to one or two, and the emergence of inhibitory circuitry. Many of these changes underlie the development of precise eye-specific visual maps and receptive field structure of LGN neurons. Retinal activity plays a major role both in the induction and maintenance of this refinement. The activity-dependent influx of Ca(2+) through L-type channels and associated activation of CREB signalling may underlie the pruning and stabilization of developing retinogeniculate connections.

The dorsal lateral geniculate nucleus (dLGN) is a model system for understanding thalamic organization and the classification of inputs as "drivers" or "modulators." Retinogeniculate terminals provide the primary excitatory drive for the relay of information to visual cortex (V1), while nonretinal inputs act in concert to modulate the gain of retinogeniculate signal transmission. How do inputs from the superior colliculus, a visuomotor structure, fit into this schema? Using a variety of anatomical, optogenetic, and in vitro physiological techniques in mice, we show that dLGN inputs from the superior colliculus (tectogeniculate) possess many of the ultrastructural and synaptic properties that define drivers. Tectogeniculate and retinogeniculate terminals converge to innervate one class of dLGN neurons within the dorsolateral shell, the primary terminal domain of direction-selective retinal ganglion cells. These dLGN neurons project to layer I of V1 to form synaptic contacts with dendrites of deeper-layer neurons. We suggest that tectogeniculate inputs act as "backseat drivers," which may alert shell neurons to movement commands generated by the superior colliculus. Significance statement: The conventional view of the dorsal lateral geniculate nucleus (dLGN) is that of a simple relay of visual information between the retina and cortex. Here we show that the dLGN receives strong excitatory input from both the retina and the superior colliculus. Thus, the dLGN is part of a specialized visual channel that provides cortex with convergent information about stimulus motion and eye movement and positioning.

In the developing mammalian visual system, axon terminals from the two eyes overlap in the dorsal lateral geniculate nucleus (LGN) but then undergo a period of refinement and segregate to form distinct eye-specific domains. We report on the changes in synaptic transmission that occur in rodent LGN during the period of retinogeniculate axon segregation by using anterograde labeling techniques in conjunction with an in vitro preparation where large segments of each optic nerve are preserved. Anterograde labeling of retinal projections in early postnatal day (P) rats with cholera toxin β subunit indicated an age-related recession in uncrossed retinal projections. Between P2 and P5 uncrossed projections occupied as much as 50% of the LGN and overlapped substantially with crossed projections. Between the first and second postnatal week uncrossed projections receded, so by P14 they assumed an adultlike profile occupying 15–20% of LGN and showed little or no overlap with crossed projections. The postsynaptic responses of LGN cells evoked by the separate stimulation of each optic nerve indicated that before P14, many relay cells were binocularly innervated and received at least four to six inputs from each eye. However, these features of retinogeniculate connectivity were transient and their attrition occurred in concert with a retraction of retinal arbors into nonoverlapping, eye-specific regions. By P18 cells were monocularly innervated and received input from one to three retinal ganglion cells. These results provide a better understanding of the underlying changes in synaptic circuitry that occur during the anatomical segregation of retinal inputs into eye-specific territories.