Research Opportunities

Our lab seeks to explore the neural mechanisms underlying cognitive function by exploiting the unique investigative opportunities provided by intracranial electrical recordings during neurosurgical procedures. Using recordings captured from epilepsy patients implanted with subdural and depth electrodes, we investigate the activation of cortical networks during memory encoding and recall. And using recordings captured during implantation of deep brain stimulators, we investigate the role of the basal ganglia in learning and decision-making.

Retroviral sequences remain dormant in the human genome and occupy nearly 7-8% of the genomic sequence. We have shown that one of these viruses termed HERV-K (HML-2) is activated in patients with amyotrophic lateral sclerosis (ALS), and transgenic animals that express the envelope protein of HERV-K develop ALS like symptoms. Hence, we are now using a wide variety of structural biology and virology tools to determine the mechanism by which its expression is regulated and causes neurotoxicity to motor neurons. 

Understand the disease mechanisms and potential treatments for hereditary motor neuron diseases such as spinal muscular atrophy and polyglutamine expansion diseases such as Huntington's disease.

Humans display robust age-dependent sex differences in diverse domains of motor, language and social development, as well as in risk for developmentally-emergent disorders. There is a robust male-bias in risk for early-emerging impairments of attention, motor control, language and social functioning, vs. a female-bias for adolescent-emergent disorders of mood and eating behaviors.  The stereotyped pattern of these sex biases suggests a role for sex differences in brain development, and further implies that these differences unfold in a spatiotemporally-specific manner. In support of this notion - in vivo structural neuroimaging studies find focal sex differences in brain anatomy that vary over development. However, the mechanisms driving these neurodevelopmental differences remain poorly understood in humans. In particular, we do not know how specific spatial and temporal instances of sex-biased brain development in humans relate to the two foundational biological differences between males and females: gonadal sex-steroid profile (henceforth “gonadal”) and X/Y-chromosome count [henceforth “sex chromosome dosage” (SCD)]. In our prior cross-sectional neuroimaging studies, we have however provided extensive evidence that gonads and SCD can both shape regional anatomy of the human brain, and that similar effects can be observed in mice. However, to date there are no available data on the temporal unfolding of gonadal and SCD effects on regional brain anatomy, and no quantitative frameworks for comparing these effects between observational humans studies and experimental work in mice.

This project will build on a longstanding productive collaboration between Drs. Lerch and Raznahan, with rich existing datasets, to better-specify sex as a neurobiological variable in health and disease. Key questions for the project relate to (i) fine-grained spatiotemporal mapping of sex, SCD and gonadal effects using neuroimaging in transgenic mice and rare patient groups, (ii) computational solutions for comparison of these maps between species, and (iii) “decoding” of imaging data using measures of gene expression in brain tissue and integrative functional genomics. The resulting anatomical, and genomic signatures for sex-biased development will be probed for association with biological bases of sex-biased brain disorders.

*This project is available for the 2021 Oxford-NIH Pilot Programme*

Use experimental medicine and neuroimaging approaches to uncover the mechanisms mood disorders in adolescents and adults. Depression is a leading cause of burden of disease worldwide yet we know little about its pathogenesis. The student is going to work across the NIMH and Oxford laboratories and use neuroimaging (fMRI, EEG and MEG) in patients and controls who undergo experimental treatments.

Midbrain dopamine neurons have fundamental roles in reward learning and movement control, and their dysfunction is associated with various disorders in particular Parkinson’s disease. Recent studies have shown substantial diversity in the activity of these neurons depending on where in the striatum their axons project. In our recent experiments we recorded the activity of dopamine axonal terminals while systematically manipulating stimuli, actions and rewards in a precise behavioural task. While the activity of dopamine projections to ventral regions of striatum mainly reflected rewards, dopamine axonal projections to dorsal striatum encoded contralateral stimuli and actions with negligible representation of reward value. These findings raise the questions of whether dopamine signals across striatum encode specific aspects of associations between stimuli, actions and rewards during learning, and whether these anatomically-specific dopamine signals are impaired during Parkinson’s disease. This project will address these questions using a combination of imaging, computational and behavioural experiments in healthy mice as well as mouse models of Parkinson’s disease. In Oxford University (Lak lab), we will use recent genetically–encoded dopamine sensors in combination with fiber photometry to monitor the dynamics of dopamine signals across the striatum while healthy mice perform a learning task guided by sensory stimuli and rewards. These results will provide a foundation for examining these dopamine signals during Parkinson’s disease, which will be performed at NIH (Cui lab). Using MitoPark mouse line (with progressive and robust phynotype of Parkinson’s disease), we will examine the dynamics of striatal dopamine signals using photometry during learning tasks established in healthy mice in Oxford. In analysing the data, we will use learning models to relate dopamine signals with normative computational models of decision making and learning. The project is primarily experimental in nature but will provide an opportunity to develop computational skills. The project will provide fundamental insights into behaviourally-relevant computations that dopamine signals across the striatum encode, and will uncover how these neuronal computations change during Parkinson’s disease. For further information visit: https://www.niehs.nih.gov/research/atniehs/labs/ln/pi/iv/index.cfm and www.laklab.org

*This project is available for the 2021 Oxford-NIH Pilot Programme*

Humans and animals adjust their feeding behaviour according to many environmental factors, including the spatial context where food is found and consumed. Such contextual control of food seeking and eating is notably central to the ability to meet future needs and maximise chances of survival to changes in feeding routines but their underpinning brain network mechanisms and pathways remain unclear. The Dupret laboratory (MRC Brain Network Dynamics Unit at the University of Oxford) investigates how the concerted spiking activity of neurons supports memory and the Krashes laboratory NIH/NIDDK) investigates homeostatic and non-homeostatic feeding behaviour. An integrated project between the two labs, in collaboration with an NIH OxCam Scholar would be designed to enable the pursuit of an Ph.D. revealing circuit mechanisms of contextual control of feeding behaviour using in vivo large-scale network recordings in behaving rodents, combined with optogenetic and closed-loop optogenetic manipulations.

Alzheimer’s disease is the most common neurodegenerative disease. It affects millions of individuals worldwide. Because of large scale genomic studies, we know a number of genetic risk factors that increase the risk for disease. We also know a few factors that promote resilience to disease onset. The Narayan lab seeks to identify, understand, and modulate the cellular pathways that underlie risk and resilience to Alzheimer’s disease.  We do this with the goal of developing new therapeutic or preventative strategies for neurodegenerative diseases. To accomplish our research goals, we use a combination of genetics, biochemistry, molecular biology, and human induced pluripotent stem cell (iPSC)-derived neuronal and glial cell types. We’re excited to welcome new team members interested in studying the cell biology behind neurodegenerative disease risk.

Neuronal plasticity is fundamental to nervous system development and function. We have recently discovered that reactive oxygen species (ROS), known for their destructive capacity in the ageing or diseased brain, function as second messengers for implementing structural plasticity at synaptic terminals. Moreover, different sources of ROS (cytoplasmic vs mitochondrially generated) regulate genetically distinct aspects of synapse development (growth vs release site number). Do ROS sculpt synapse plasticity in response to the metabolic state of neurons? How does ROS signaling intersect with other signaling pathways regulating synaptic plasticity, such as BMP and Wnt? This project will combine biochemical and genetic approaches with electrophysiology and methods for live and super-resolution imaging to investigate the contribution of various signaling pathways to synapse plasticity. We expect this project to redefine our understanding of how multiple signaling pathways integrate at the synapse to regulate distinct elements of plasticity.