Tag Archive for: Aaron Sathyanesan

Purkinje cell

Premature birth disrupts Purkinje cell function, resulting in locomotor learning deficits

Purkinje cell

Children’s National Hospital researchers explored how preterm birth disrupts Purkinje cell function, resulting in locomotor learning deficits.

As the care of preterm babies continues to improve, neonatologists face new challenges to ensure babies are protected from injury during critical development of the cerebellum during birth and immediately after birth. How does this early injury affect locomotor function, and to what extent are clinicians able to protect the brain of preterm babies?

A new peer-reviewed study by Aaron Sathyanesan, Ph.D., Panagiotis Kratimenos, M.D., Ph.D., and Vittorio Gallo, Ph.D., published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS), explores exactly what neural circuitry of the cerebellum is affected due to complications that occur around the time of birth causing these learning deficits, and finds a specific type of neurons — Purkinje cells — to play a central role.

Up until now, there has been a sparsity of techniques available to measure neuronal activity during locomotor learning tasks that engage the cerebellum. To surmount this challenge, Children’s National used a multidisciplinary approach, bringing together a team of neuroscientists with neonatologists who leveraged their joint expertise to devise a novel and unique way to measure real-time Purkinje cell activity in a pre-clinical model with clinical relevance to humans.

Researchers measured neural circuit function by pairing GCaMP6f fiber photometry, used to measure neuronal activity in the brain of a free moving subject, with an ErasmusLadder, in which it needs to travel from point A to point B on a horizontal ladder with touch-sensitive rungs that register the type and length of steps. By introducing a sudden obstacle to movement, researchers observed how the subject coped and learned accordingly to avoid this obstacle. By playing a high-pitch tone just before the obstacle was introduced, researchers were able to measure how quickly the subjects were able to anticipate the obstacle and adjust their steps accordingly. Subjects with neonatal brain injury and normal models were run through a series of learning trials while simultaneously monitoring brain activity. In this way, the team was able to quantify cerebellum-dependent locomotor learning and adaptive behavior, unlocking a functional and mechanistic understanding of behavioral pathology that was previously unseen in this field.

In addition to showing that normal Purkinje cells are highly active during movement on the ErasmusLadder, the team explored the question of whether Purkinje cells of injured pre-clinical models were generally non-responsive to any kind of stimuli. They found that while Purkinje cells in injured subjects responded to puffs of air, which generally cue the subject to start moving on the ErasmusLadder, dysfunction in these cells was specific to the period of adaptive learning. Lastly, through chemogenetic inhibition, which specifically silences neonatal Purkinje cell activity, the team was able to mimic the effects of perinatal cerebellar injury, further solidifying the role of these cells in learning deficits.

The study results have implications for clinical practice. As the care of premature babies continues to improve, neonatologists face new challenges to ensure that babies not only survive but thrive. They need to find ways to prevent against the lifelong impacts that preterm birth would otherwise have on the cerebellum and developing brain.

Read the full press release here.

Read the full journal article here.

illustration of brain showing cerebellum

NIH grant supports research on locomotor dysfunction in Down Syndrome

illustration of brain showing cerebellum

The National Institutes of Health (NIH) has granted the Children’s National Research Institute (CNRI) nearly $500,000 to better understand and identify specific alterations in the circuitry of the cerebellum that results in locomotor dysfunction in down syndrome.

Down syndrome (DS), the most commonly diagnosed chromosomal condition, affects a range of behavioral domains in children including motor and cognitive function. Cerebellar pathology has been consistently observed in DS, and is thought to contribute to dysfunction in locomotor and adaptive motor skills. However, the specific neural pathways underlying locomotor learning that are disrupted in DS remain poorly understood.

The National Institutes of Health (NIH) has granted the Children’s National Research Institute (CNRI) nearly $500,000 through their NIH-wide initiative INCLUDE – INvestigating Co-occurring conditions across the Lifespan to Understand Down syndrome – to better understand and identify specific alterations in the circuitry of the cerebellum that results in locomotor dysfunction in DS. The INCLUDE initiative aims to support the most promising high risk-high reward basic science.

“There is still a lot unknown about Down syndrome, in particular how fundamental cellular and physiological mechanisms of neural circuit function are altered in this syndrome,” says Vittorio Gallo, Ph.D., chief research officer at Children’s National Hospital and scientific director of CNRI. “Grant funding is particularly important to have the resources to develop and apply new cutting-edge methodology to study this neurodevelopmental disorder.”

The main goal of this research is to identify specific alterations in the circuitry of the cerebellum that result in locomotor dysfunction in DS. Defining specific abnormalities in motor behavior, and identifying the brain regions and neurons which are functionally involved will provide the basis for developing potential therapies for treating motor problems in individuals with DS.

“The last decade has brought rapid advances in neurotechnology to address questions at the ‘systems-level’ understanding of brain function,” says Aaron Sathyanesan, Ph.D., a Children’s National postdoctoral research fellow. “This technology has rarely been applied to preclinical models of neurodevelopmental disorders, and even more rarely to models of Down syndrome.”

An example is the use of fiber-optics to probe changes in neural circuitry during behavior. Using this technology, researchers can now directly correlate the changes in circuitry to deficits in behavior.

“Along with the other approaches in our proposal, this represents the synthesis of a new experimental paradigm that we hope will push the field forward,” says Dr. Sathyanesan.

In 1960, the average life expectancy of a baby with Down syndrome was around 10 years. Today, that life expectancy has increased to more than 47 years. That significant increase reflects critical advances in medicine, however, kids with DS still live with long-term challenges in motor and cognitive ability.

Children’s National strongly supports translation and innovation, and recently recruited internationally renowned DS researcher, Tarik Haydar, Ph.D., as its new director of the Center for Neuroscience Research.

“We’re building significant strength in this area of research. This grant helps open new avenues of investigation to define which cells and circuits are impacted by this common neurodevelopmental disorder,” says Dr. Gallo. “Our cutting-edge approach will help us answer questions that we could not answer before.”

Vittorio Gallo

Special issue of “Neurochemical Research” honors Vittorio Gallo, Ph.D.

Vittorio Gallo

Investigators from around the world penned manuscripts that were assembled in a special issue of “Neurochemical Research” that honors Vittorio Gallo, Ph.D., for his leadership in the field of neural development and regeneration.

At a pivotal moment early in his career, Vittorio Gallo, Ph.D., was accepted to work with Professor Giulio Levi at the Institute for Cell Biology in Rome, a position that leveraged courses Gallo had taken in neurobiology and neurochemistry, and allowed him to work in the top research institute in Italy directed by the Nobel laureate, Professor Rita Levi-Montalcini.

For four years as a student and later as Levi’s collaborator, Gallo focused on amino acid neurotransmitters in the brain and mechanisms of glutamate and GABA release from nerve terminals. Those early years cemented a research focus on glutamate neurotransmission that would lead to a number of pivotal publications and research collaborations that have spanned decades.

Now, investigators from around the world who have worked most closely with Gallo penned tributes in the form of manuscripts that were assembled in a special issue of “Neurochemical Research” that honors Gallo “for his contributions to our understanding of glutamatergic and GABAergic transmission during brain development and to his leadership in the field of neural development and regeneration,” writes guest editor Arne Schousboe, of the University of Copenhagen in Denmark.

Dr. Gallo as a grad student

Vittorio Gallo, Ph.D. as a 21-year-old mustachioed graduate student.

“In spite of news headlines about competition in research and many of the negative things we hear about the research world, this shows that research is also able to create a community around us,” says Gallo, chief research officer at Children’s National Hospital and scientific director for the Children’s National Research Institute.

As just one example, he first met Schousboe 44 years ago when Gallo was a 21-year-old mustachioed graduate student.

“Research can really create a sense of community that we carry on from the time we are in training, nurture as we meet our colleagues at periodic conferences, and continue up to the present. Creating community is bi-directional: influencing people and being influenced by people. People were willing to contribute these 17 articles because they value me,” Gallo says. “This is a lot of work for the editor and the people who prepared papers for this special issue.”

In addition to Gallo publishing more than 140 peer-reviewed papers, 30 review articles and book chapters, Schousboe notes a number of Gallo’s accomplishments, including:

  • He helped to develop the cerebellar granule cell cultures as a model system to study how electrical activity and voltage-dependent calcium channels modulate granule neuron development and glutamate release.
  • He developed a biochemical/neuropharmacological assay to monitor the effects of GABA receptor modulators on the activity of GABA chloride channels in living neurons.
  • He and Maria Usowicz used patch-clamp recording and single channel analysis to demonstrate for the first time that astrocytes express glutamate-activated channels that display functional properties similar to neuronal counterparts.
  • He characterized one of the spliced isoforms of the AMPA receptor subunit gene Gria4 and demonstrated that this isoform was highly expressed in the cerebellum.
  • He and his Children’s National colleagues demonstrated that glutamate and GABA regulate oligodendrocyte progenitor cell proliferation and differentiation.
Purkinje cells

Purkinje cells are large neurons located in the cerebellum that are elaborately branched like interlocking tree limbs and represent the only source of output for the entire cerebellar cortex.

Even the image selected to grace the special issue’s cover continues the theme of continuity and leaving behind a legacy. That image of Purkinje cells was created by a young scientist who works in Gallo’s lab, Aaron Sathyanesan, Ph.D. Gallo began his career working on the cerebellum – a region of the brain important for motor control – and now studies with a team of scientists and clinician-scientists Purkinje cells’ role in locomotor adaptive behavior and how that is disrupted after neonatal brain injury.

“These cells are the main players in cerebellar circuitry,” Gallo says. “It’s a meaningful image because goes back to my roots as a graduate student and is also an image that someone produced in my lab early in his career. It’s very meaningful to me that Aaron agreed to provide this image for the cover of the special issue.”