Welcome! Our lab is broadly interested in understanding how the body and brain encode environmental stimuli, such as daily changes in light and feeding patterns, to timely coordinate physiology and behavior.

New space, new ideas, and recruitment for multiple positions at all levels… Stay tuned for more details!

Our Lab’s logo highlights the role of the visual system in processing daily changes in light and dark, causing the alignment of internal time-keeping mechanisms. Our main source of (infrared, visible, and ultraviolet) light is provided by the Sun, which has guided the evolution of life on Earth. The general design of the logo was inspired by paintings and sculptures by Salvador Dalí and Alberto Giacometti, two of the most influential artists of the 20th century. Further, the logo is a statement that diversity, equity, inclusion, and cultural identity matters. The colors used to represent the Sunlight spectrum celebrate the different rainbow flags, and the stars are inspired by the symbolic art from the native people of South America.

Our research focus

Animal physiology is profoundly modulated by daily changes in light. In mammals, light is detected by the retina and routed by projection neurons to brain nuclei. Among them, visual centers drive image-forming functions, whereas a wide range of retino-recipient brain targets process light signals to control innate processes, including sleep/wake cycles, rhythmic metabolic processes, and affective behavior. In the lab we apply a curiosity-driven approach to address some of the following questions:

What are the mechanisms that allow us to extract time information from changes in light?

Are these mechanisms similar to those that generate an internal representation of the visual scene?

Can lighting conditions affect the way the brain communicates with other systems?

What are the processes that govern the development of circuits processing environmental signals?

Results obtained from this basic approach become relevant for elucidating the neuronal basis of disorders linked to deleterious environmental factors, such as light pollution and circadian stressors or disruptors, and thus, expanding the opportunities to develop innovative therapeutics strategies. In a broader view, understanding how artificial light affects our physiology is critical in the design of better lighting conditions for improving human health and to reduce its environmental impact.

Neuronal circuits mediating the effects of light on mood and cognition

We recently identified the perihabenular nucleus (PHb), a thalamic hub interconnected with limbic areas, which processes light to control mood in mice. In parallel, light signals relayed by the suprachiasmatic nucleus (SCN) affect hippocampal functions and learning. Current research aims to identify the distinct features of these light-sensing circuits that mediate the deleterious effects of irregular light exposure.

Note: The diagram represents a sagittal section of a mouse brain showing the parallel retina-brain circuits (Fernandez et al., Cell 2018).

Photic perception within visual and non-visual thalamic circuits

Image-forming vision is driven by a well-known nucleus of the thalamus, the dLGN, which routes light signals to the visual cortex. Our research aims to uncover novel retina-thalamus circuits that, beyond image-forming vision, modulate subconscious and innate functions, including alertness, sleep/wake cycles, and mood-related behavior.

Note: A section of a mouse brain is shown; tracers (cyan) were used to identify retinal input to image-forming (dLGN) and mood-regulating (PHb) centers in the thalamus (Weil et al., Science Advances 2022).

Effects of lighting conditions on feeding responses

Sensory systems extract time information from many environmental cues, affecting rhythmic processes. Among external cues, food access is critical for survival. In the lab we investigate the mechanisms controlling rhythmic aspects of food seeking and feeding behavior across the day/night cycle, as well as how different lighting conditions and retinal signals modulate food consumption.

Note: The model highlights the role of retinal input in modulating the crosstalk between metabolic and circadian centers (IGL-SCN), which timely coordinate mouse activity (Fernandez et al., Nature 2020).

Sensory and circadian systems development and maturation

The central circadian pacemaker of the suprachiasmatic nucleus (SCN) receives retinal information, setting internal time-keeping mechanisms. Multiple brain and systemic signals, collectively known as non-photic cues, also adjust SCN’s rhythms. In the lab we investigate the mechanisms that guide the proper assembly of circuits linking sensory and circadian systems during developmental stages.

Note: The model represents the patterns of projections driving photic (green) and metabolic (red) information to the SCN (Fernandez et al., PNAS 2016, Fernandez et. al., Nature 2020).

Meet the lab

Our lab embraces and promotes diversity, equity, and inclusion. We base our strengths in teamwork, and believe that the most efficient way to achieve goals is though the collective search and discussion of ideas and approaches.


Interested in a postdoctoral position? Send us an email describing your background and scientific interests, and why you are interested in our lab. Please also include contact information for 3 references.

Are you a graduate student interested in the lab?  Please contact us! Students from a range of backgrounds, including neuroscience, biology, chemistry, engineering, and psychology are welcome.


Assistant Professor

Diego is a Latin American Scientist who received his Ph.D. from the University of Buenos Aires, Argentina (mentor: Dr. Ruth Rosenstein), where he developed innovative interventions for diabetic retinopathy. Following up on his interest in studying retina-related processes, Diego joined the lab of Dr. Samer Hattar at Johns Hopkins University, with the support of the Pew Postdoctoral Fellows Award. His work demonstrated that the light information requires different retina-brain circuits to influence mood versus learning. Diego then joined the NIH, as Staff Scientist and then as an Associate Scientist at the Section of Light and Circadian Rhythms (NIMH), where he expanded his studies on the light effects on mood and started a new line of research aimed to investigate how the retina and light signals affect brain circuits that control feeding responses.
In 2023 Diego joined the Cincinnati Children’s Hospital Medical Center (CCHMC), Pediatric Ophthalmology Division, and the Science of Light Center, as an Assistant Professor.


Erin Matthews, B.S.

Research Associate

Erin graduated from Northern Kentucky University in 2022 with B.S. in neuroscience and psychology. She gained experience in variety of laboratory environments, from rodents to wild birds, and has growing interest in research focused on the interaction between brain structures and behavior.

Kat Castleberry, CCRP

Research Supervisor

Amanda Hilligan

Grants Coordinator



Selected Publications available with direct PDF download


Follow the link for complete list of publications: Diego C. Fernandez – NCBI

Weil et al., Science Advances 2022. We investigated the cellular pathways in the perihabenular nucleus (PHb) driving mood dysregulation caused by irregular light exposure. 

Fernandez et al., Nature 2020. Here we revealed a new role for retinal innervation: it shapes the assembly of circadian brain centers that timely control feeding responses in mice.

Fernandez et al., Cell 2018. We revealed that distinct neuronal pathways drive the effects of light on learning and mood. We also identified the PHb as a thalamic hub controlling mood.

Fernandez et al., PNAS 2016. Here we used  tracing of retinal projection neurons, at a single cell level, to comprehensively delineate their elaborate patterns of brain innervation.

Zhan et al., JoVE 2019. In this video-protocol we described different alternatives for delivering the ligand CNO to chronically manipulate DREADD-controlled neurons in mice.

LeGates et al., Nature Reviews Neuroscience 2014. Here we reviwed and discussed recent basic and translational studies that investigated the influence of light on mood regulation.

Fernandez et al., The American Journal of Pathology 2012. We revealed that alterations at the distal portion of the optic nerve are one of the first changes in the diabetic visual pathway.

Fernandez et al., Chronobiology International 2013. In this study we analyzed the long-term deficits in the non-image-forming visual system caused by experimental diabetes. 

To contact the Fernandez Lab:

Cincinnati Children’s Hospital Medical Center

Division of Pediatric Ophthalmology

3333 Burnet Ave R2447

Cincinnati; State: Ohio, 45230

Useful links:

Cincinnati Children’s DEI strategic plan <Link>

Division of Pediatric Ophthalmology at CCHMC <Link>

Center for Pediatric Neurosceince at CCHMC <Link>

Molecular & Developmental Biology Graduate Program at Cincinnati Children’s Hospital Medical Center <Link>

Neuroscience Graduate Program at the University of Cincinnati <Link>


Intersections Science Fellows Symposium 2021. Diego’s presentation during the Neuroscience session <Link>

NPR article, by Jon Hamilton: Are You Sad in the Winter? Scientists May Have Figured Out Why <Link>

PNAS journal club: Tracing light’s effect on mood and learning in mice from the eye to deep within the brain <Link>

The Scientist, by Catherine Offord. Winter Brain Blues <Link>

Promega Connections, by Kari Kenefick. Light: A Happy Pill for Dark Days? <Link>