Visual Functions of the Thalamus

Usrey, W. Martin; Alitto, Henry J.

doi:10.1146/annurev-vision-082114-035920

Cited by 118 publications

(80 citation statements)

References 145 publications

(222 reference statements)

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“…Converging weak inputs could synchronize the activity of groups of dLGN neurons, providing effective coincident stimuli for cortical activation (Alonso et al, 2006). They may also improve signal-to-noise in thalamic circuits to enhance perceptual acuity, create novel receptive fields that increase the continuity in visual or temporal space, or form novel feature detectors absent in the retina (Martinez et al, 2014; Usrey and Alitto, 2015). Finally, small inputs may support adult plasticity of RG connectivity through changes in synaptic weight (Litvina and Chen, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

“…Such extensive RG convergence challenges existing models of RG function (Alonso et al, 2006; Martinez et al, 2014; Usrey and Alitto, 2015), and suggests significant thalamic processing and sensory integration of visual information. However, these studies were performed from postnatal day (P)21–42, when experience-dependent functional rewiring of the circuit and RGC axon retraction and pruning is still occurring (Hong et al, 2014).…”

Section: Introductionmentioning

confidence: 88%

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Functional Convergence at the Retinogeniculate Synapse

Litvina

Chen

2017

Neuron

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Summary Precise connectivity between retinal ganglion cells (RGCs) and thalamocortical (TC) relay neurons is thought to be essential for the transmission of visual information. Consistent with this view, electrophysiological measurements have previously estimated that 1–3 retinal ganglion cells (RGCs) converge onto a mouse geniculate TC neuron. Recent advances in connectomics and rabies tracing have yielded much higher estimates of retinogeniculate convergence, although not all identified contacts may be functional. Here we use optogenetics and a computational simulation to determine the number of functionally relevant retinogeniculate inputs onto TC neurons in mice. We find an average of 10 RGCs converging onto a mature TC neuron, in contrast to >30 inputs before developmental refinement. However, only 30% of retinogeniculate inputs exceed the threshold for dominating postsynaptic activity. These results signify a greater role for the thalamus in visual processing and provide a functional perspective of anatomical connectivity data.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

Functional Convergence at the Retinogeniculate Synapse

Litvina

Chen

2017

Neuron

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“…In vivo , the retinogeniculate synapse has been a prominent model system for the study of sub-cortical visual processing. Numerous studies have capitalized on the ease of manipulating visual stimulation, combined with the ability to simultaneously monitor the activity patterns of inputs and outputs of the thalamus to reliably demonstrate that the transfer of information from the retina to the visual cortex is the major function of the retinogeniculate synapse (Sherman, 2005; Usrey & Alitto, 2015; Weyand, 2016). …”

Section: More Than a Relaymentioning

confidence: 99%

“…The simplest circuit, where 1 RGC contacts 1 TC neuron, is most consistent with the concept of a thalamic “relay” (Glees & Le Gros Clark, 1941; Sherman & Guillery, 1996). More complex circuits with converging RGC inputs and/or diverging single RGC axons onto multiple target TC neurons increase the likelihood of the emergence of novel visual features or receptive field properties (Dan et al, 1998; Alonso et al, 2006; Koepsell et al, 2009; Usrey & Alitto, 2015; Sherman, 2016; Weyand, 2016). For these reasons, studies quantifying connectivity, and in particular, the degree of retinogeniculate convergence, is an active area of research.…”

Section: Retinogeniculate Connectivitymentioning

confidence: 99%

An evolving view of retinogeniculate transmission

Litvina

Chen

2017

Vis Neurosci

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The thalamocortical (TC) relay neuron of the dorsoLateral Geniculate Nucleus (dLGN) has borne its imprecise label for many decades in spite of strong evidence that its role in visual processing transcends the implied simplicity of the term “relay”. The retinogeniculate synapse is the site of communication between a retinal ganglion cell and a TC neuron of the dLGN. Activation of retinal fibers in the optic tract causes reliable, rapid, and robust postsynaptic potentials that drive postsynaptics spikes in a TC neuron. Cortical and subcortical modulatory systems have been known for decades to regulate retinogeniculate transmission. The dynamic properties that the retinogeniculate synapse itself exhibits during and after developmental refinement further enrich the role of the dLGN in the transmission of the retinal signal. Here we consider the structural and functional substrates for retinogeniculate synaptic transmission and plasticity, and reflect on how the complexity of the retinogeniculate synapse imparts a novel dynamic and influential capacity to subcortical processing of visual information.

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“…Importantly, both interpolation (implemented through retina-LGN convergence) and LCE (implemented through local interneurons) appear to be evolutionary conserved (34). This computational conservation may be surprising, as the LGN of the primate is a layered structure, containing independent channels of information with distinct contrast and color content, a feature that does not appear to exist in the mouse (35). …”

Section: Thalamic Organization and Evidence For Conservation Of Circumentioning

confidence: 99%

Interrogating the mouse thalamus to correct human neurodevelopmental disorders

Schmitt

Halassa

2016

Mol Psychiatry

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While localizing sensory and motor deficits is one of the cornerstones of clinical neurology, behavioral and cognitive deficits in psychiatry remain impervious to this approach. In psychiatry, major challenges include the relative subtlety by which neural circuits are perturbed, and the limited understanding of how basic circuit functions relate to thought and behavior. Neurodevelopmental disorders offer a window to addressing the first challenge given their strong genetic underpinnings, which can be linked to biological mechanisms. Such links have benefited from genetic modeling in the mouse, and in this review we highlight how this small mammal is now allowing us to crack neural circuits as well. We review recent studies of mouse thalamus, discussing how they revealed general principles that may underlie human perception and attention. Controlling the magnitude (gain) of thalamic sensory responses is a mechanism of attention, and the mouse has enabled its functional dissection at an unprecedented resolution. Further, modeling human genetic neurodevelopmental disease in the mouse has shown how diminished thalamic gain control can lead to attention deficits. This breaks new ground in how we untangle the complexity of psychiatric diseases; by making thalamic circuits accessible to mechanistic dissection, the mouse has not only taught us how they fundamentally work, but also how their dysfunction can be precisely mapped onto behavioral and cognitive deficits. Future studies promise even more progress, with the hope that principled targeting of identified thalamic circuits can be uniquely therapeutic.

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Visual Functions of the Thalamus

Cited by 118 publications

References 145 publications

Functional Convergence at the Retinogeniculate Synapse

Functional Convergence at the Retinogeniculate Synapse

An evolving view of retinogeniculate transmission

Interrogating the mouse thalamus to correct human neurodevelopmental disorders

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