Marcos Aranda, PhD
I study how light shapes physiology and behavior in health and disease. I use the intrinsically photosensitive retinal ganglion cells (ipRGCs) — a well-conserved, genetically tractable population that drives a broad range of measurable physiological and behavioral outputs — as a window into the brain.
One photoreceptor, three questions
ipRGCs sit at the intersection of vision, physiology and behavior. My program follows that intersection in three directions: how light-driven circuits shape cognitive behavior, how internal states tune visual circuits, and how they could serve as early biomarkers and therapeutic tools for disease.
Light and cognition
Using a behavioral paradigm I developed — Long-Term Threat Avoidance (LTTA) — I study how ipRGC-driven visual circuits shape memory and decision-making. My lab asks how animals use light to learn about, remember, and act on their environment.
Internal states and circuit tuning
I found that circulating sex hormones shape how visual circuits tune cognitive behavior. My lab will study how internal states more broadly — hormones among them — tune these circuits and the behaviors they drive.
The retina, a window to brain health
ipRGCs are a well-conserved, highly and specifically tractable cell population that drives a broad spectrum of measurable physiological and behavioral outputs — many of which are impaired early in neurodegenerative disease. I'm using this ideal system as a source of early biomarkers and potential intervention targets in neurodegenerative disease models.
Techniques
The approaches I use to move between molecules, circuits, and behavior — from a single cell type to a freely moving animal.
Transcriptomics
snRNA-seq and TRAP-seq to map molecular identity and early markers across ipRGC subtypes.
Genetic mouse lines
Intersectional Cre/Flp driver crosses for cell-type-specific access to individual circuit nodes.
Circuit manipulation
DREADDs, optogenetics, and AAV-based tools to causally test circuit function in vivo.
Surgical tools
Stereotaxic injections, fiber-photometry and infusion cannulas, GRIN lenses, gonadectomies.
Behavioral analysis
Machine learning pipelines.
In vivo imaging
Fiber photometry and miniscope calcium imaging of circuit activity in freely behaving mice.
Selected work
Light gates hormonal modulation of threat avoidance in female mice
Light tunes a long-term threat avoidance behavior in male mice
Genetic tuning of retinal ganglion cell subtype identity to drive visual behavior
An ethologically relevant paradigm to assess visual contrast sensitivity in rodents
Diversity of intrinsically photosensitive retinal ganglion cells: circuits and functions
Trajectory
Employment & Education
Mentoring & Training
I've mentored students and trainees across Argentina, Mexico, and the United States spanning undergraduate researchers to PhD students, in translational neuroscience, circuit tracing/manipulation, and computational analysis of behavior.