Inhibitory control of feature selectivity in an object motion sensitive circuit of the retina

Object motion sensitive (OMS) W3-retinal ganglion cells (W3-RGCs) in mice respond to local movements in a visual scene but remain silent during self-generated global image motion. The excitatory inputs that drive responses of W3-RGCs to local motion were recently characterized, but which inhibitory neurons suppress W3-RGCs’ responses to global motion, how these neurons encode motion information, and how their connections are organized along the excitatory circuit axis remains unknown. Here, we find that a genetically identified amacrine cell (AC) type, TH2-AC, exhibits fast responses to global motion and slow responses to local motion. Optogenetic stimulation shows that TH2-ACs provide strong GABAA receptor-mediated input to W3-RGCs but only weak input to upstream excitatory neurons. Cell-type-specific silencing reveals that temporally coded inhibition from TH2-ACs cancels W3-RGC spike responses to global but not local motion stimuli and, thus, controls the feature selectivity of OMS signals sent to the brain

Organization of the dorsal lateral geniculate nucleus in the mouse

AbstractThe 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.</jats:p

Glutamatergic retinal waves

Spontaneous activity patterns propagate through many parts of the developing nervous system and shape the wiring of emerging circuits. Prior to vision, waves of activity originating in the retina propagate through the lateral geniculate nucleus (LGN) of the thalamus to primary visual cortex (V1). Retinal waves have been shown to instruct the wiring of ganglion cell axons in LGN and of thalamocortical axons in V1 via correlation-based plasticity rules. Across species, retinal waves mature in three stereotypic stages (I-III), in which distinct circuit mechanisms give rise to unique activity patterns that serve specific functions in visual system refinement. Here, I review insights into the patterns, mechanisms, and functions of stage III retinal waves, which rely on glutamatergic signaling. As glutamatergic waves spread across the retina, neighboring ganglion cells with opposite light responses (ON vs. OFF) are activated sequentially. Recent studies identified lateral excitatory networks in the inner retina that generate and propagate glutamatergic waves, and vertical inhibitory networks that desynchronize the activity of ON and OFF cells in the wavefront. Stage III wave activity patterns may help segregate axons of ON and OFF ganglion cells in the LGN, and could contribute to the emergence of orientation selectivity in V1

Synaptic remodeling of neuronal circuits in early retinal degeneration

Photoreceptor degenerations are a major cause of blindness and among the most common forms of neurodegeneration in humans. Studies of mouse models revealed that synaptic dysfunction often precedes photoreceptor degeneration, and that abnormal synaptic input from photoreceptors to bipolar cells causes circuits in the inner retina to become hyperactive. Here, we provide a brief overview of frequently used mouse models of photoreceptor degenerations. We then discuss insights into circuit remodeling triggered by early synaptic dysfunction in the outer and hyperactivity in the inner retina. We discuss these insights in the context of other experimental manipulations of synaptic function and activity. Knowledge of the plasticity and early remodeling of retinal circuits will be critical for the design of successful vision rescue strategies

An excitatory amacrine cell detects object motion and provides feature-selective input to ganglion cells in the mouse retina

Retinal circuits detect salient features of the visual world and report them to the brain through spike trains of retinal ganglion cells. The most abundant ganglion cell type in mice, the so-called W3 ganglion cell, selectively responds to movements of small objects. Where and how object motion sensitivity arises in the retina is incompletely understood. In this study, we use 2-photon-guided patch-clamp recordings to characterize responses of vesicular glutamate transporter 3 (VGluT3)-expressing amacrine cells (ACs) to a broad set of visual stimuli. We find that these ACs are object motion sensitive and analyze the synaptic mechanisms underlying this computation. Anatomical circuit reconstructions suggest that VGluT3-expressing ACs form glutamatergic synapses with W3 ganglion cells, and targeted recordings show that the tuning of W3 ganglion cells' excitatory input matches that of VGluT3-expressing ACs' responses. Synaptic excitation of W3 ganglion cells is diminished, and responses to object motion are suppressed in mice lacking VGluT3. Object motion, thus, is first detected by VGluT3-expressing ACs, which provide feature-selective excitatory input to W3 ganglion cells. DOI: http://dx.doi.org/10.7554/eLife.08025.00

Das Haus beim oberen Markttor. Baugeschichte des Anwesens Kerschensteiner in Parsberg 1826 bis 2012

Seit 1826 ist das Anwesen Nr. 54 (später Marktstraße 5) in Parsberg mit dem Namen Kerschensteiner verbunden. Bis zum Jahr 2012 haben insgesamt sechs Generationen der Familie das Anwesen als Eigentümer bewirtschaftet. Im April 2012 ist nun das Grundstück im Rahmen der Stadtsanierung auf die Stadt Parsberg als neuen Eigentümer übergegangen. Während der Räumung konnten unzählige Gegenstände, Dokumente und Abbildungen geborgen werden, die – nach umfangreicher Aufarbeitung – einen umfassenden Überblick über die Familiengeschichte eröffnen und zugleich als Fallstudie der regionalen Wirtschaftsgeschichte dienen. Da die Sichtung und Einordnung des umfangreichen Materials bei Weitem noch nicht abgeschlossen ist, soll weder die Familiengeschichte noch die Wirtschaftsgeschichte des Hauses Inhalt dieser Broschüre sein, vielmehr geht es in erster Linie um die Baugeschichte des Gebäudes. Insofern werden hier familien- und wirtschaftsgeschichtliche Gegebenheiten nur so weit kurz wiedergegeben, als sie zum Verständnis der baulichen Entwicklungen erforderlich sind. Es werden Entwicklungen nachgezeichnet, die einerseits auf überlieferten Kenntnissen beruhen und andererseits allgemein dokumentierte ortsgeschichtliche Ereignisse einbeziehen (etwa die Brandkatastrophe von 1841). Als Hauptquellen dienen hierbei die Parsberger Chronik von Alfred Spitzner aus dem Jahre 1950 in der aufbereiteten Version von Manfred Eglmeier 2003, der ISEK-Innenstadt Endbericht der Stadt Parsberg von Architekt Rainer Heinz aus dem Jahr 2010 sowie der Urkataster von 1830 und dessen Nachfolger aus dem Jahre 1859, erhältlich bei der BLO (Bayerische Landesbibliothek Online)

Integrated photoacoustic, confocal, and two-photon microscope

The invention of green fluorescent protein and other molecular fluorescent probes has promoted applications of confocal and two-photon fluorescence microscopy in biology and medicine. However, exogenous fluorescence contrast agents may affect cellular structure and function, and fluorescence microscopy cannot image nonfluorescent chromophores. We overcome this limitation by integrating optical-resolution photoacoustic microscopy into a modern Olympus IX81 confocal, two-photon, fluorescence microscope setup to provide complementary, label-free, optical absorption contrast. Automatically coregistered images can be generated from the same sample. Imaging applications in ophthalmology, developmental biology, and plant science are demonstrated. For the first time, in a familiar microscopic fluorescence imaging setting, this trimodality microscope provides a platform for future biological and medical discoveries