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HomeUCLA Brain Research Institute (BRI)  > People  > Research Areas (FARs)
Ranmal Samarasignhe, Ph.D.

Ranmal Samarasignhe, M.D., Ph.D.

Biography

Dr. Ranmal Samarasinghe received his MD and PhD degrees from the University of Pittsburgh in 2013. He completed his residency in adult neurology at UCLA in 2017 and then completed an NIH funded post-doctoral research and clinical fellowship at UCLA from 2017-2020. During this period, Dr. Samarasinghe obtained clinical training in epilepsy and neurophysiologic intraoperative monitoring. He also performed research developing stem cell-based models of epilepsy and autism, which is the foundation of his own laboratory.

Dr. Samarasinghe’s laboratory seeks to understand the mechanisms of neural network formation and dysfunction in epilepsy and autism. His efforts are focused on 3D brain-like structures called human brain organoids that are grown in a laboratory dish and that are derived from stem cells. Brain organoids can be generated from the stem cells of individual patients and may provide unique insights into the causes of human neurological diseases such as epilepsy and autism. His laboratory is developing and utilizing multiple methodologies including whole-organoid multiphoton based calcium indicator imaging, voltage sensors, traditional extracellular recordings, high throughput genomic screens, and super-resolution synaptic imaging to interrogate the developmental trajectory of nascent neural networks in organoid models. Dr. Samarasinghe will also continue to manage patients with epilepsy and autism in his clinic and perform neurophysiologic intraoperative monitoring for surgical cases performed at UCLA and affiliated hospitals.

Andrew M. Wikenheiser, Ph.D.

Andrew Wikenheiser, Ph.D.

Biography

Our lab studies how neural representations support behaviors like decision making. We approach this question by recording the electrical activity of neurons as rats perform behavioral tasks. Electrophysiological techniques are augmented with optogenetics and computational analyses. Current projects are exploring how interactions between the hippocampus and the orbitofrontal cortex support decision making, the encoding of spatial goals, and the formation of neural representations for abstract stimulus spaces.

Publications

A selected list of publications:

Wikenheiser Andrew M, Marrero-Garcia Yasmin, Schoenbaum Geoffrey   Suppression of Ventral Hippocampal Output Impairs Integrated Orbitofrontal Encoding of Task Structure Neuron, 2017; 95(5): 1197-1207.e3.
Langdon Angela J, Wikenheiser Andrew M, Schoenbaum Geoffrey   Rat mPFC and M2 Play a Waiting Game (at Different Timescales) Neuron, 2017; 94(4): 700-702.
Sadacca Brian F, Wikenheiser Andrew M, Schoenbaum Geoffrey   Toward a theoretical role for tonic norepinephrine in the orbitofrontal cortex in facilitating flexible learning Neuroscience, 2017; 345(4): 124-129.
Wikenheiser Andrew M, Schoenbaum Geoffrey   Over the river, through the woods: cognitive maps in the hippocampus and orbitofrontal cortex Nature reviews. Neuroscience, 2016; 17(8): 513-23.
Sharpe Melissa J, Wikenheiser Andrew M, Niv Yael, Schoenbaum Geoffrey   The State of the Orbitofrontal Cortex Neuron, 2015; 88(6): 1075-1077.
Wikenheiser Andrew M, Redish A David   Decoding the cognitive map: ensemble hippocampal sequences and decision making Current opinion in neurobiology, 2015; 32(6): 8-15.
Wikenheiser Andrew M, Redish A David   Hippocampal theta sequences reflect current goals Nature neuroscience, 2015; 18(2): 289-94.
Wikenheiser Andrew M, Stephens David W, Redish A David   Subjective costs drive overly patient foraging strategies in rats on an intertemporal foraging task Proceedings of the National Academy of Sciences of the United States of America, 2013; 110(20): 8308-13.
Wikenheiser Andrew M, Redish A David   The balance of forward and backward hippocampal sequences shifts across behavioral states Hippocampus, 2013; 23(1): 22-9.
Wikenheiser Andrew M, Redish A David   Hippocampal sequences link past, present, and future Trends in cognitive sciences, 2012; 16(7): 361-2.
Wikenheiser Andrew M, Redish A David   Changes in reward contingency modulate the trial-to-trial variability of hippocampal place cells Journal of neurophysiology, 2011; 106(2): 589-98.
Shulamite Green, Ph.D.

Shulamite Green, Ph.D.

Biography

Dr. Shulamite Green is an Assistant Professor in the Department of Psychiatry and Biobehavioral Sciences at UCLA’s Semel Institute. Dr. Green received a Ph.D. in Clinical Psychology at UCLA in 2014. Thereafter, she completed a postdoctoral fellowship at the UCLA Ahmanson-Lovelace Brain Mapping Center with a focus on pediatric neuroimaging. Dr. Green is currently the director of the Sensory, Cognitive, and Affective Neurodevelopment (SCAN) lab. Dr. Green’s research integrates multiple neuroimaging techniques with behavioral and psychophysiological methodology to determine the biological mechanisms underlying clinical symptoms in a way that can be directly translated to creating interventions and improving quality of life. Much of Dr. Green’s current research is focused on the neurobiological bases of sensory over-responsivity, a common and impairing condition in which individuals over-react to sensory stimuli in their environments, causing challenges with participation in school, work, family life, and the community. Dr. Green conducted some of the first fMRI work demonstrating brain differences in children with autism spectrum disorders (ASD) specifically related to sensory over-responsivity, as well as identifying potential brain mechanisms through which some children with ASD regulate their sensory responses. She has continued to build on this work to identify how certain brain areas contribute to or regulate these difficulties and interfere with or facilitate attention and social functioning.

Dr. Green also has a strong interest in the impact of parenting and early caregiving adversity on development, with much of her early work focused on how parenting can confer resilience for children with developmental disabilities. Her current NIH-funded K08 career development award is focused on examining how common and distinct neural, behavioral, and clinical correlates of sensory over-responsivity in children adopted from foster care compared to those with autism.

In addition to the K08 award, Dr. Green’s work has been funded by multiple NIH grants, including a recent R01 from NIMH to study the development of sensory regulation across childhood and adolescence, and has been published in prominent scientific journals including JAMA Psychiatry , the American Journal of Psychiatry , the Journal of Child Psychology and Psychiatry, and Translational Psychiatry . Dr. Green is also the recipient of a dissertation award from the International Society for Autism Research as well as a Brain and Behavioral Research Institute Young Investigator Award.

Dr. Green is passionate about mentoring as well as promoting justice, equity, diversity, and inclusion (JEDI) in her lab, the department, and academia in general. She co-leads the teaching and mentoring JEDI group for the Center for Autism Research and Treatment (CART), and holds monthly JEDI meetings in her lab.

Clinically, Dr. Green serves as the autism specialist for UCLA TIES for Families, a program that provides extensive inter-disciplinary services for families adopting children from foster care. Dr. Green conducts autism evaluations and consultations for therapists working with families in this program.

View a up-to-date publication list: NCBI

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