About

David M. Berson is the Sidney A. Fox and Dorothea Doctors Fox Professor of Ophthalmology and Visual Science at Brown University. He has been a faculty member since 1985, having completed his undergraduate and postdoctoral studies at Brown. His research focuses on the structure and function of the visual system, particularly on retinal neurons that send information directly to visual centers of the brain. His lab studies the types of retinal output cells, including their anatomical and physiological features, and their roles in visual behaviors. Notably, he has contributed to the discovery that some retinal output cells are true photoreceptors that respond directly to light, influencing biological rhythms and pupil constriction. Additionally, his work investigates how retinal cells work and how their signals are used by the brain to stabilize our view of the world. Berson also teaches neuroanatomy and neurophysiology to undergraduate, graduate, and medical students.

Research topics

• Biology
• Neuroscience
• Biochemistry
• Materials science
• Cell biology
• Endocrinology
• Chemistry

Selected publications

• Bipolar cell networks underlying steady-state intensity encoding in intrinsically photosensitive retinal ganglion cells

  iScience · 2026-02-13

  articleOpen accessSenior author

  Intrinsically photosensitive retinal ganglion cells (ipRGCs) encode ambient light intensity at steady-state and drive physiology even in the absence of melanopsin, but the synaptic basis of such encoding remains unclear. Using ultrastructural reconstructions, we mapped specific bipolar cell (BC) types and synapses conveying photoreceptor input to ipRGCs. Functional imaging showed BC glutamate release onto ipRGCs encodes intensity at steady-state, though release onto other RGCs also exhibits such encoding. Disrupting inhibition on BCs spared intensity-encoding release at ipRGC strata but reduced it elsewhere, consistent with inhibition shifting BC dynamic range. Recording postsynaptic excitatory currents showed that ipRGCs better preserve BC-derived intensity encoding than conventional RGCs. Thus, ipRGCs receive excitation from selected, inhibition-resistant BCs whose steady-state release encodes intensity. This, together with the enhanced preservation of postsynaptic intensity encoding, ensures reliable ipRGC intensity signaling independent of visual contrast to drive physiology and behavior.

  PublisherDOI

• Cone bipolar cell synapses generate transient versus sustained signals in parallel ON pathways of the mouse retina

  eLife · 2025-12-22

  articleOpen access

  Parallel processing is a fundamental organizing principle in the nervous system and understanding how parallel neural circuits generate distinct outputs from common inputs is a key goal of neuroscience. In the mammalian retina, divergence of cone signals into multiple feedforward bipolar cell pathways forms the initial basis for parallel retinal circuits dedicated to specific visual functions. Here, we used patch-clamp electrophysiology, electron microscopy, and two-photon imaging of a fluorescent glutamate sensor to examine how kinetically distinct responses arise in transient versus sustained ON alpha retinal ganglion cells (ON-T and ON-S RGCs) of the mouse retina. We directly compared the visual response properties of these RGCs with their presynaptic bipolar cell partners, which we identified using 3D electron microscopy reconstruction. Different ON bipolar cell subtypes (types 5i, 6, and 7) had indistinguishable light-driven responses whereas extracellular glutamate signals around RGC dendrites and postsynaptic excitatory currents measured in ON-T and ON-S RGCs in response to the identical stimuli used to probe bipolar cells were kinetically distinct. Anatomical examination of the bipolar cell axon terminals presynaptic to ON-T and ON-S RGCs suggests that bipolar subtype-specific differences in the size of synaptic ribbon-associated vesicle pools may contribute to transient versus sustained kinetics. Our findings indicate that feedforward bipolar cell synapses are a primary point of divergence in kinetically distinct visual pathways.

  PublisherDOI

• Cone bipolar cell synapses generate transient versus sustained signals in parallel ON pathways of the mouse retina

  eLife · 2025-08-21

  articleOpen access

  Abstract Parallel processing is a fundamental organizing principle in the nervous system and understanding how parallel neural circuits generate distinct outputs from common inputs is a key goal of neuroscience. In the mammalian retina, divergence of cone signals into multiple feedforward bipolar cell pathways forms the initial basis for parallel retinal circuits dedicated to specific visual functions. Here, we used patch-clamp electrophysiology, electron microscopy and two photon imaging of a fluorescent glutamate sensor to examine how kinetically-distinct responses arise in transient versus sustained ON alpha RGCs (ON-T and ON-S RGCs) of the mouse retina. We directly compared the visual response properties of these RGCs with their presynaptic bipolar cell partners, which we identified using 3D electron microscopy reconstruction. Different ON bipolar cell subtypes (type 5i, type 6 and type 7) had indistinguishable light-driven responses whereas extracellular glutamate signals around RGC dendrites and postsynaptic excitatory currents measured in ON-T and ON-S RGCs in response to the identical stimuli used to probe bipolar cells were kinetically distinct. Anatomical examination of the bipolar cell axon terminals presynaptic to ON-T and ON-S RGCs suggests that bipolar subtype-specific differences in the size of synaptic ribbon-associated vesicle pools may contribute to transient versus sustained kinetics. Our findings indicate that feedforward bipolar cell synapses are a primary point of divergence in kinetically distinct visual pathways.

  PublisherDOI

• Author response: Cone bipolar cell synapses generate transient versus sustained signals in parallel ON pathways of the mouse retina

  2025-08-21

  peer-reviewOpen access

  Parallel processing is a fundamental organizing principle in the nervous system and understanding how parallel neural circuits generate distinct outputs from common inputs is a key goal of neuroscience. In the mammalian retina, divergence of cone signals into multiple feedforward bipolar cell pathways forms the initial basis for parallel retinal circuits dedicated to specific visual functions. Here, we used patch-clamp electrophysiology, electron microscopy and two photon imaging of a fluorescent glutamate sensor to examine how kinetically-distinct responses arise in transient versus sustained ON alpha RGCs (ON-T and ON-S RGCs) of the mouse retina. We directly compared the visual response properties of these RGCs with their presynaptic bipolar cell partners, which we identified using 3D electron microscopy reconstruction. Different ON bipolar cell subtypes (type 5i, type 6 and type 7) had indistinguishable light-driven responses whereas extracellular glutamate signals around RGC dendrites and postsynaptic excitatory currents measured in ON-T and ON-S RGCs in response to the identical stimuli used to probe bipolar cells were kinetically distinct. Anatomical examination of the bipolar cell axon terminals presynaptic to ON-T and ON-S RGCs suggests that bipolar subtype-specific differences in the size of synaptic ribbon-associated vesicle pools may contribute to transient versus sustained kinetics. Our findings indicate that feedforward bipolar cell synapses are a primary point of divergence in kinetically distinct visual pathways.

  PublisherDOI

• Efficacy and specificity of melanopsin reporters for retinal ganglion cells

  The Journal of Comparative Neurology · 2024-02-01 · 10 citations

  articleOpen accessSenior author

  Abstract Intrinsically photosensitive retinal ganglion cells (ipRGCs) are specialized retinal output neurons that mediate behavioral, neuroendocrine, and developmental responses to environmental light. There are diverse molecular strategies for marking ipRGCs, especially in mice, making them among the best characterized retinal ganglion cells (RGCs). With the development of more sensitive reporters, new subtypes of ipRGCs have emerged. We therefore tested high‐sensitivity reporter systems to see whether we could reveal yet more. Substantial confusion remains about which of the available methods, if any, label all and only ipRGCs. Here, we compared many different methods for labeling of ipRGCs, including anti‐melanopsin immunofluorescence, Opn4‐GFP BAC transgenic mice, and Opn4 cre mice crossed with three different Cre‐specific reporters (Z/EG, Ai9, and Ai14) or injected with Cre‐dependent (DIO) AAV2. We show that Opn4 cre mice, when crossed with sensitive Cre‐reporter mice, label numerous ganglion cell types that lack intrinsic photosensitivity. Though other methods label ipRGCs specifically, they do not label the entire population of ipRGCs. We conclude that no existing method labels all and only ipRGCs. We assess the appropriateness of each reporter for particular applications and integrate findings across reporters to estimate that the overall abundance of ipRGCs among mouse RGCs may approach 11%.

  PublisherOA PDFDOI

• Cone bipolar cell synapses generate transient versus sustained signals in parallel ON pathways of the mouse retina

  eLife · 2024-08-20 · 2 citations

  preprintOpen access

  Abstract Parallel processing is a fundamental organizing principle in the nervous system, and understanding how parallel neural circuits generate distinct outputs from common inputs is a key goal of neuroscience. In the mammalian retina, divergence of cone signals into multiple feed-forward bipolar cell pathways forms the initial basis for parallel retinal circuits dedicated to specific visual functions. Here, we used patch-clamp electrophysiology, electron microscopy and two photon imaging of a fluorescent glutamate sensor to examine how kinetically distinct responses arise in transient versus sustained ON alpha RGCs (ON-T and ON-S RGCs) of the mouse retina. We directly compared the visual response properties of these RGCs with their presynaptic bipolar cell partners, which we identified using 3D electron microscopy reconstruction. Different ON bipolar cell subtypes (type 5i, type 6 and type 7) had indistinguishable light-driven responses whereas extracellular glutamate signals around RGC dendrites and postsynaptic excitatory currents measured in ON-T and ON-S RGCs in response to the identical stimuli used to probe bipolar cells were kinetically distinct. Anatomical examination of the bipolar cell axon terminals presynaptic to ON-T and ON-S RGCs suggests bipolar subtype-specific differences in the size of synaptic ribbon-associated vesicle pools may contribute to transient versus sustained kinetics. Our findings indicate bipolar cell synapses are a primary point of divergence in kinetically distinct visual pathways.

  PublisherDOI

• The retina’s neurovascular unit: Müller glial sheaths and neuronal contacts

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-01 · 6 citations

  preprintOpen access

  Summary The neurovascular unit (NVU), comprising vascular, glial and neural elements, supports the energetic demands of neural computation, but this aspect of the retina’s trilaminar vessel network is poorly understood. Only the innermost vessel layer – the superficial vascular plexus (SVP) – is ensheathed by astrocytes, like brain capillaries, whereas glial ensheathment in other layers derives from radial Müller glia. Using serial electron microscopy reconstructions from mouse and primate retina, we find that Müller processes cover capillaries in a tessellating pattern, mirroring the tiled astrocytic endfeet wrapping brain capillaries. However, gaps in the Müller sheath, found mainly in the intermediate vascular plexus (IVP), permit different neuron types to contact pericytes and the endothelial cells directly. Pericyte somata are a favored target, often at spine-like structures with a reduced or absent vascular basement lamina. Focal application of adenosine triphosphate (ATP) to the vitreal surface evoked Ca 2+ signals in Müller sheaths in all three vascular layers. Pharmacological experiments confirmed that Müller sheaths express purinergic receptors that, when activated, trigger intracellular Ca 2+ signals that are amplified by IP 3 -controlled intracellular Ca 2+ stores. When rod photoreceptors die in a mouse model of retinitis pigmentosa ( rd10 ), Müller sheaths dissociate from the deep vascular plexus (DVP) but are largely unchanged within the IVP or SVP. Thus, Müller glia interact with retinal vessels in a laminar, compartmentalized manner: glial sheathes are virtually complete in the SVP but fenestrated in the IVP, permitting direct neural-to-vascular contacts. In the DVP, the glial sheath is only modestly fenestrated and is vulnerable to photoreceptor degeneration.

  PublisherOA PDFDOI

• Layer-specific anatomical and physiological features of the retina’s neurovascular unit

  Current Biology · 2024-12-16 · 22 citations

  articleOpen access

  stores. When rod photoreceptors die in a mouse model of retinitis pigmentosa (rd10), Müller sheaths dissociate from the deep vascular plexus (DVP) but are largely unchanged within the IVP or SVP. Thus, Müller glia interact with retinal vessels in a laminar, compartmentalized manner: glial sheaths are virtually complete in the SVP but fenestrated in the IVP, permitting direct neurovascular contacts. In the DVP, the glial sheath is only modestly fenestrated and is vulnerable to photoreceptor degeneration.

  PublisherDOI

• A Specialized Bipolar Cell Network Underlies Intensity Encoding in Intrinsically Photosensitive Retinal Ganglion Cells

  SSRN Electronic Journal · 2024-01-01

  preprintOpen accessSenior author
  PublisherDOI

• Cone bipolar cell synapses generate transient versus sustained signals in parallel ON pathways of the mouse retina

  eLife · 2024-08-20 · 1 citations

  preprintOpen access

  Parallel processing is a fundamental organizing principle in the nervous system and understanding how parallel neural circuits generate distinct outputs from common inputs is a key goal of neuroscience. In the mammalian retina, divergence of cone signals into multiple feedforward bipolar cell pathways forms the initial basis for parallel retinal circuits dedicated to specific visual functions. Here, we used patch-clamp electrophysiology, electron microscopy, and two-photon imaging of a fluorescent glutamate sensor to examine how kinetically distinct responses arise in transient versus sustained ON alpha retinal ganglion cells (ON-T and ON-S RGCs) of the mouse retina. We directly compared the visual response properties of these RGCs with their presynaptic bipolar cell partners, which we identified using 3D electron microscopy reconstruction. Different ON bipolar cell subtypes (types 5i, 6, and 7) had indistinguishable light-driven responses whereas extracellular glutamate signals around RGC dendrites and postsynaptic excitatory currents measured in ON-T and ON-S RGCs in response to the identical stimuli used to probe bipolar cells were kinetically distinct. Anatomical examination of the bipolar cell axon terminals presynaptic to ON-T and ON-S RGCs suggests that bipolar subtype-specific differences in the size of synaptic ribbon-associated vesicle pools may contribute to transient versus sustained kinetics. Our findings indicate that feedforward bipolar cell synapses are a primary point of divergence in kinetically distinct visual pathways.

  PublisherDOI

Recent grants

• Structure and Function of Mammalian Ganglion Cells

  NIH · $9.3M · 2000–2024

• NIH Grant R01EY017137

  NIH · $2.9M · 2016

• NIH Grant R21EY026735

  NIH · $426k · 2019

• NIH Grant R01EY006108

  NIH · $1.4M · 2000

Frequent coauthors

• Kwoon Y. Wong

  University of Michigan–Ann Arbor

  66 shared

• Shi-Jun Weng

  State Key Laboratory of Medical Neurobiology

  52 shared

• Shai Sabbah

  Hebrew University of Jerusalem

  43 shared

• Samer Hattar

  National Institutes of Health

  38 shared

• Lauren E. Quattrochi

  Providence College

  37 shared

• Megan L. Leyrer

  John Brown University

  37 shared

• Maureen E. Estevez

  Providence College

  36 shared

• Jordan M. Renna

  University of Akron

  34 shared

Education

• B.S.

  Brown University

• Ph.D.

  Brown University