Past events

Abstract: In many regions of the brain, neurons form an ordered representation of the outside world. For example, the 'homunculus' of the somatosensory cortex is a point-to-point topographic map of the body surface onto the brain surface. The spatially organized convergence of sensory inputs often leads to similar response properties in target neurons that are in close vicinity. Whether their individual information content is redundant or independent depends on the circuit architecture (the interplay between common input, lateral signals and feedback from other brain areas) and the computational goals of the network. In the mammalian olfactory bulb (OB), sensory neurons expressing the same type of olfactory receptor (~10,000) converge in tight focus, forming clusters of synapses called glomeruli (~2,000). From each glomerulus, a few dozen mitral cells (principal output neurons of the OB) carry the output further to the cortex. The mitral cells, typically have only one primary dendrite that projects to a single glomerulus, but can sample inputs on their primary and secondary dendrites from functionally diverse glomeruli via several types of interneurons. Thus, a few dozen mitral cells share input from the same parent glomerulus, but may have different inhibitory surrounds. In the first part of this talk, I will discuss the topographic layout of glomeruli on the bulb - the olfactory map. How precise is this map within and across two species: mouse and rat? How does its structure relate to odor processing? Do glomeruli that are responsive to structurally similar odor molecules have a tendency to lie next to each other? In other words, is there a chemotopic map? In the second part of the talk, I will focus on probing the odor response properties of mitral cells using extracellular recordings and an optogenetic strategy to ask whether the OB is more than a relay station. Do mitral cells receiving common input from the same parent glomerulus carry redundant information about odors to cortex? I will conclude by describing novel strategies that allow monitoring the input-output transfer function of the OB via multi-photon microscopy imaging of bulb neurons activity in the same animal, in different states of the circuit. Link for further information: http://www.cshl.edu/public/SCIENCE/albeanu.html

Social relationships are at the core of every healthy society and the quality of early social attachments contributes to emotional and social development. I will discuss the neurobiological mechanisms underlying social attachment and bonding, as well as the impact of early life social experience on later life social relationships. The highly social and monogamous prairie vole is an ideal animal model for investigating the biological mechanisms of social attachment and bonding. Studies in voles have revealed that the neuropeptides oxytocin and vasopressin promote social bonding. Furthermore, variation in the oxytocin and vasopressin systems contributes to diversity in social behavior both across species and within populations. I will discuss the genetic mechanisms giving rise to diversity in social organization in voles. Finally I will discuss parallels between these studies in voles and recent studies in humans which suggest that these mechanisms are highly conserved from rodent to man. These observations have important implications for psychiatric disorders characterized by disruptions in social behavior, including autism.

Behavioral and theoretical studies have focused on identifying the kinematic and temporal characteristics of various movements ranging from simple reaching to complex 2D and 3D drawing and curved motions. These kinematic and temporal features are quite instrumental in investigating the organizing principles that underlie trajectory formation. Similar kinematic constraints play also a critical role in visual perception of abstract as well as biological motion stimuli and in action recognition. In my talk I will review the results of recent studies showing that 2D and 3D movements might be represented in terms of non-Euclidian metrics. I will also present a recent extension of these studies leading to a new theory which suggests that movement duration, invariance, and compositionality may arise from cooperation among several geometries. The theory has led to concrete predictions which were corroborated by the kinematic and temporal features of both drawing and locomotion trajectories. Finally I will discuss the findings of several behavioral and brain mapping studies aiming at identifying the neural correlates of the suggested organizing principles.