Tag Archives: hibernation

Dr. Bryan William Jones Awarded RPB Stein Innovation Award

We are pleased to reveal that Dr. Bryan William Jones has been selected for an RPB Stein Innovation Award from Research to Prevent Blindness. This particular project is something that we’ve been scheming for a while and leverages an approach to comparative anatomy to study the ground squirrel retina.  The unique thing about the 12-lined ground squirrel retina is that the photoreceptors of this organism degenerate when it hibernates.  The outer segments of the photoreceptors degenerate and the synapses that connect them to the first synapse of the visual system dissolves in much the same way as when the retina degenerates in human diseases like retinitis pigmentosa, and age-related macular degeneration.  The trick is: When the 13-lined ground squirrel comes out of hibernation, their retinas regenerate and their synapses reconnect giving us an incredible opportunity to explore plasticity in their nervous systems.

Seasonal And Post-Trauma Remodeling Of The Ground Squirrel Retina

We have a new publication out, Seasonal and post-trauma remodeling in cone-dominant ground squirrel retina authored by Dana Merriman, Ben Sajdak, Wei Li and Bryan W. Jones.


With a photoreceptor mosaic containing ∼85% cones, the ground squirrel is one of the richest known mammalian sources of these important retinal cells. It also has a visual ecology much like the human’s. While the ground squirrel retina is understandably prominent in the cone biochemistry, physiology, and circuitry literature, far less is known about the remodeling potential of its retinal pigment epithelium, neurons, macroglia, or microglia. This review aims to summarize the data from ground squirrel retina to this point in time, and to relate them to data from other brain areas where appropriate. We begin with a survey of the ground squirrel visual system, making comparisons with traditional rodent models and with human. Because this animal’s status as a hibernator often goes unnoticed in the vision literature, we then present a brief primer on hibernation biology. Next we review what is known about ground squirrel retinal remodeling concurrent with deep torpor and with rapid recovery upon re-warming. Notable here is rapidly-reversible, temperature-dependent structural plasticity of cone ribbon synapses, as well as pre- and post-synaptic plasticity throughout diverse brain regions. It is not yet clear if retinal cell types other than cones engage in torpor-associated synaptic remodeling. We end with the small but intriguing literature on the ground squirrel retina’s remodeling responses to insult by retinal detachment. Notable for widespread loss of (cone) photoreceptors, there is surprisingly little remodeling of the RPE or Müller cells. Microglial activation appears minimal, and remodeling of surviving second- and third-order neurons seems absent, but both require further study. In contrast, traumatic brain injury in the ground squirrel elicits typical macroglial and microglial responses. Overall, the data to date strongly suggest a heretofore unrecognized, natural checkpoint between retinal deafferentiation and RPE and Müller cell remodeling events. As we continue to discover them, the unique ways by which ground squirrel retina responds to hibernation or injury may be adaptable to therapeutic use.