Laboratory of Brain Circuits Therapeutics
My laboratory has expertise in synthetic biology, which we aim to apply toward brain therapeutics. We have developed novel chemically-controlled genetic switches to investigate genes and brain circuits in different neuro-biological processes (Dogbevia et al., Front Cell Neurosci. 9:142, 2015, Dogbevia et al., Mol Ther Nucleic Acids. 5:e309, 2016). We have also developed genetic methods for mapping and manipulating local and distributed brain circuits either individually or in combinations in a cell type specific manner. By understanding the operating principle of brain circuits in generating simple and complex behavior, we project that it would be possible to tackle a number of psychiatric and neurological diseases, such as post-traumatic stress disorder, autism spectrum disorder, schizophrenia, Parkinson's and Alzheimer's diseases. My lab is dedicated in the development of innovative approaches, based on biochemical, genetic and cellular therapeutics, to protect and treat brain circuits along the continuum of disease onset and progression.
To understand disease mechanisms, it is imperative to consider the key players of brain circuits, the interplay between neurons, glia (astrocytes and microglia) and extracellular matrix (ECM). The pre- and postsynaptic compartments and astrocytes membranes form the tripartite synapse, and with the ECM (i.e., perineuronal net), the tetrapartite synapse. Synaptic circuits and astrocytic processes provide vital intercellular bidirectional communication in the organization of the tripartite synapse. Understanding how neuron-astrocyte signaling influences neuronal excitatory/inhibitory synaptic balance would provide crucial insight into the functions of brain circuits. To investigate the role of tripartite synapse in synaptic plasticity and behavior, we have selectively manipulated neurons and astrocytes in the primary motor cortex (M1). Virus-delivered inducible block of the NMDA receptor in the M1 neurons in mice impaired trace eyeblink conditioning and synaptic plasticity, providing the first demonstration that cortical synaptic plasticity alone is responsible for memory formation (Hasan et al., Nat Commun. 4:2258, 2013). To investigate what role do astrocytes play, we performed genetic-assisted blocking of gliotransmission and discovered that it impaired NMDA receptor-dependent long-term synaptic depression (Navarette et al., Nat Commun. 10(1):2968, 2019). It is known that astrocytes also express NMDA receptors, but their role in memory processes have remained elusive. We hypothesized that astrocytes NMDARs control gliotransmission. When we removed NMDA receptors in the M1 astrocytes, we have recently discovered that learning was affected differently for the different cues (in preparation). These findings place the tripartite synapse as the fundamental functional unit in the organization of brain circuit function, and its implications in pathological processes is an unexplored territory. To make advances in this field, mapping and manipulating "activated" circuits would be crucial. For this purpose, we have developed a novel tool for virus-delivered Genetic Activity-induced Tagging of cell Ensembles (vGATE) (Hasan et al., Neuron 103(1):133-146.e8, 2019), that can be targeted to entire cell assemblies or even specific cell types. With the vGATE technology, we discovered that an evolutionarily older brain structure, such as the hypothalamus generates context- and cell type-specific fear memory engrams. We have also found that cued-fear memory engrams are sequentially printed from one brain region to the next and, subsequently, across the different brain regions by using the "systems consolidation" mechanism (in preparation).
For mapping activated brain circuits, I conceived and developed the ideas and published two seminal scientific articles describing new methods that have transformed the research in systems neuroscience, making transformational impacts in contributing towards understanding healthy nervous systems and different psychiatric and neurological diseases: (1) demonstrated the use of genetic calcium indicators for cell type specific synaptic activity mapping in brain slices and brain-wide sensory signal-evoked activity mapping by in vivo wide-field imaging in living mammals (Hasan et al., PLoS Biol. 2(6):e163, 2004) and (2) with cellular and single action potential resolution (Wallace et al., Nat Methods. 5(9):797-804, 2008). Moreover, we demonstrated for the first time genetic calcium activity imaging in freely moving mammals (Lütcke et al., Front Neural Circuits. 4:9, 2010). Our work further demonstrated by chronic in vivo two-photon activity imaging that general anesthetics can synchronize cellular calcium transients, disrupting functional cortico-cortical connections to sensory-evoked responses (Lissek et al., Front Cell Neurosci. 10:64, 2016), providing insight into the mechanism(s) of unconsciousness (by anesthesia) and perhaps consciousness in the future. With an advanced gene control switch to inducibly and reversibly control synaptic transmission (vINSIST; virus-delivery Inducible Silencing of Synaptic Tramission), we have recently shown that claustrum, considered as a key center for consciousness, is needed for the formation of cognitive abilities, but not for their expression (Mar Reus-García et al., Cerebral Cortex bhaa225, 2020). To understand how the different brain regions interact with each other during sensory information processing, decision-making and motor output as in behavioral responses, it is necessary to be able to map the activity of the entire brain. Therefore, full brain mapping of activated brain circuits would make a transformational impact in systems neuroscience. To achieve this goal, my lab has developed Genetically-Encoded Magnetic Indicators (GEMIs) for activity mapping of simple and complex experiences across different brain regions. We are performing genetic-assisted MRI of labeled brain networks in collaboration with Prof. Dr. Pedro Ramos-Cabrer at the CIC biomaGUNE (San Sebastian, Spain) and Prof. Dr. Jesus M. Cortes at the BioCruces Bizkaia Health Research Institute (Bilbao, Spain) (in preparation).
All these tools provide a unique platform for investigating disease mechanisms and the potential for brain circuits therapeutics.
Cell type specific inducible gene deletion, inducible gene expression systems, two-photon calcium imaging, confocal microscopy, bioluminescence imaging, opto- and pharmacogenetics, synapse labeling, circuit mapping, and different behavioral paradigms, genetic MRI for full brain scale activity mapping.