The newly established Silva lab is seeking a Postdoctoral Fellow to study midline thalamic circuits in fear memory and fear extinction in the mouse. The Silva lab combines whole-brain functional tracing, chemogenetics, optogenetics and in vivo fiber photometry to investigate thalamic circuits involved in emotional regulation. We recently discovered that the nucleus reuniens of the thalamus mediates extinction of remote (older than 30 days) fear memories (Silva et al. Nat. Neurosci. 2021) and we are currently working to unravel its functional upstream and downstream partners. The successful candidate will design and implement experiments to elucidate and characterize the NRe-centered whole-brain circuit and identify its putative neurophysiological impairments in mouse models of PTSD. Experience with behavioral studies, stereotactic surgeries, programming, whole-brain microscopy or causal neuroscience is a plus, but is not required. The successful candidate should be highly motivated and have the ability to successfully lead a research project. The Silva lab is affiliated to the Institute of Neuroscience at the National Research Council of Italy and is located at the Neurocenter of the Humanitas Research Hospital in Rozzano, MI (https://www.humanitas-research.org/). Applicants should contact Bianca Silva (bianca.silva@in.cnr.it) with a current CV and a motivation letter. The position is full-time for 1 year, and renewable for other two. The position is immediately available and is funded by a 3-year grant by Cariplo Foundation. Within the first year, application to prestigious international postdoctoral fellowships (EMBO, Marie Curie, HFSP) is highly encouraged. Selected candidates will be directly contacted for interviews. After interview two reference letters will be requested.

Maladaptive emotional memories contribute to the persistence of numerous mental health disorders, including post-traumatic stress disorder (PTSD), drug addiction and obsessive-compulsive disorder (OCD). Using rodent behavioural models of the psychological processes relevant to these disorders, it is possible to identify potential treatment targets for the development of new therapies, including those based upon disrupting the reconsolidation of maladaptive emotional memories. Using examples from rodent models relevant to multiple mental health disorders, this talk will consider some of the opportunities and challenges that this approach provides.

Post traumatic stress disorder (PTSD) is a prevalent and disabling condition that affects larger numbers of children and adolescents worldwide. Until recently, we have understood little about the nature of PTSD reactions in our youngest children (aged under 8 years old). This talk describes our work over the last 15 years working with this very young age group. It overviews how we need a markedly different PTSD diagnosis for very young children, data on the prevalence of this new diagnostic algorithm, and the development of a psychological intervention and its evaluation in a clinical trial.

Dysregulation of emotional processing and its integration with cognitive functions are central features of many mental/emotional disorders associated both with externalizing problems (aggressive, antisocial behaviors) and internalizing problems (anxiety, depression). As Dr. Joseph LeDoux, our invited speaker of this program, wrote in his famous book “Synaptic self: How Our Brains Become Who We Are”—the brain’s synapses—are the channels through which we think, act, imagine, feel, and remember. Synapses encode the essence of personality, enabling each of us to function as a distinctive, integrated individual from moment to moment. Thus, exploring the functioning of synapses leads to the understanding of the mechanism of (patho)physiological function of our brain. In this context, we have investigated the pathophysiology of psychiatric disorders, with particular emphasis on the synaptic function of model mice of various psychiatric disorders such as schizophrenia, autism, depression, and PTSD. Our current interest is how synaptic inputs are integrated to generate the action potential. Because the spatiotemporal organization of neuronal firing is crucial for information processing, but how thousands of inputs to the dendritic spines drive the firing remains a central question in neuroscience. We identified a distinct pattern of synaptic integration in the disease-related models, in which extra-large (XL) spines generate NMDA spikes within these spines, which was sufficient to drive neuronal firing. We experimentally and theoretically observed that XL spines negatively correlated with working memory. Our work offers a whole new concept for dendritic computation and network dynamics, and the understanding of psychiatric research will be greatly reconsidered. The second half of my talk is the development of a novel synaptic tool. Because, no matter how beautifully we can illuminate the spine morphology and how accurately we can quantify the synaptic integration, the links between synapse and brain function remain correlational. In order to challenge the causal relationship between synapse and brain function, we established AS-PaRac1, which is unique not only because it can specifically label and manipulate the recently potentiated dendritic spine (Hayashi-Takagi et al, 2015, Nature). With use of AS-PaRac1, we developed an activity-dependent simultaneous labeling of the presynaptic bouton and the potentiated spines to establish “functional connectomics” in a synaptic resolution. When we apply this new imaging method for PTSD model mice, we identified a completely new functional neural circuit of brain region A→B→C with a very strong S/N in the PTSD model mice. This novel tool of “functional connectomics” and its photo-manipulation could open up new areas of emotional/psychiatric research, and by extension, shed light on the neural networks that determine who we are.

Understanding how the brain uses information is a fundamental goal of neuroscience. Several human disorders (ranging from autism spectrum disorder to PTSD to Alzheimer’s disease) may stem from disrupted information processing. Therefore, this basic knowledge is not only critical for understanding normal brain function, but also vital for the development of new treatment strategies for these disorders. Memory may be defined as the retention over time of internal representations gained through experience, and the capacity to reconstruct these representations at later times. Long-lasting physical brain changes (‘engrams’) are thought to encode these internal representations. The concept of a physical memory trace likely originated in ancient Greece, although it wasn’t until 1904 that Richard Semon first coined the term ‘engram’. Despite its long history, finding a specific engram has been challenging, likely because an engram is encoded at multiple levels (epigenetic, synaptic, cell assembly). My lab is interested in understanding how specific neurons are recruited or allocated to an engram, and how neuronal membership in an engram may change over time or with new experience. Here I will describe both older and new unpublished data in our efforts to understand memories in mice.