Past events

: A longstanding question at the nexus of cognition and neuroscience concerns the distribution of the labor of learning across different brain systems: what are the different ways in which the brain learns? Recent research has focused on the role of the striatum and midbrain dopamine regions in habitual learning of stimulus-reward associations. However, emerging evidence suggests that the hippocampus – widely known for its role in building flexible memories – is also modulated by reward and innervated by dopamine. This raises new hypotheses about the role of the hippocampus in learning, the unique contributions of the hippocampus and the striatum, and the nature of the relationship between them. I will present studies that address these hypotheses using an integrative approach that combines functional imaging (fMRI) in healthy individuals with studies of learning in patients with selective damage to the striatum or the hippocampus. Converging data from these approaches suggests that both the striatum and the hippocampus contribute to learning, with distinct implications for how learned information guides decisions.

Prof. Kleinfeld will present recent work on the control of rhythmic whisking in rodents. These studies bear on the apparent role of breathing as a master clock that drives orofacial actions, establishes a hierarchy of control of orofacial behaviors, and may temporally bind different orofacial inputs.

Academic achievements such as math and reading are key predictors for future success at school, university, and later in life. Additionally, failure in these critical capacities negatively impacts the welfare of society as a whole. Current understanding of the link between high-level cognition, such as math and reading, and the brain has been primarily restricted to understanding the relationship between brain structure or function. At the same time a substantial body of animal and clinical research showing that cortical inhibition and excitation at the molecular or cellular levels play a critical role in efficient information transfer in the brain. It has further been suggested that cortical inhibition and excitation affects cognition in humans. I will present several studies that show how cortical inhibition and excitation are linked to high-level cognitive abilities in the child and adult human brain, and specifically how we can exogenously modulate cortical inhibition and excitation to optimise brain functions and improve cognition in typical and atypical populations. Such a multidisciplinary approach has the potential to bridge the separated strands of current research in psychology and education, system and molecular neuroscience, as well as animal models.

The computational power of single neurons has long been predicted using modelling approaches, but actual experimental examples of how neurons, and in particular their dendrites, can solve computational problems are rare. I will describe experiments using 2-photon glutamate uncaging in vitro, combined with in vivo 2-photon imaging and patch-clamp recording that demonstrate how active dendrites contribute to shaping canonical cortical computations.

Hunger involves complex cognitive functions that rely on the physiological need for energy. The profound impact that hunger has on complex behaviors indicates that neuronal circuitries that promote hunger should control higher brain functions. I will present evidence that activation of hunger-promoting AgRP neurons in the arcuate nucleus of the hypothalamus readily triggers changes in higher brain regions and behaviors, allocating a time-budget to consummatory responses (e.g., eating). In the absence of food, activation of these neurons leads to vast induction of repetitive behaviors, which can be prevented by using serotonin and dopamine reuptake inhibitors. Thus, we unmasked a hypothalamic neuronal population that regulates both homeostatic functions and complex behaviors. More readings: Hypothalamic control of energy balance: insights into the role of synaptic plasticity. Marcelo O Dietrich, Tamas L Horvath. Trends in Neurosciences ; 2013. DOI:10.1016/j.tins.2012.12.005 AgRP neurons regulate development of dopamine neuronal plasticity and nonfood-associated behaviors. Marcelo O Dietrich, Jeremy Bober, Jozélia G Ferreira, Luis A Tellez, Yann S Mineur, Diogo O Souza, Xiao-Bing Gao, Marina R Picciotto, Ivan Araújo, Zhong-Wu Liu, Tamas L Horvath. Nature Neuroscience 2012; 15(8):1108-10 AgRP neurons: the foes of reproduction in leptin-deficient obese subjects. Marcelo O Dietrich, Tamas L Horvath. Proceedings of the National Academy of Sciences.2012; 109(8):2699-700 See also: http://www.researchgate.net/profile/Marcelo_Dietrich/publications/

Abstract: Songbirds are a great model for studying how the brain solves the challenges of vocal imitation, because, like human infants, young songbirds learn to produce complex vocal sequences that are exact copies of those of adult conspecifics. To study how this feat is accomplished, we experimentally induce birds to perform song learning tasks, by exposing them sequentially to two different songs and recording their entire vocal output during the process. Applying this methodology to vocal combinatorial learning, we trained juvenile zebra finches to swap syllable order in their song, or insert a new syllable into a string. Birds solved these permutation tasks gradually, by a series of steps in which novel pair-wise transitions between syllables were acquired one by one. This effect was confirmed in the development of vocal babbling in human infants, suggesting the existence of a common generative process of acquiring vocal combinatorial ability that is conserved across species. We next used the same methodology to study the conversion of an auditory memory of a target song into a motor program performing the same song, a long-standing hypothesis in vocal learning. To do this, we induced birds to change both global song structure (syllable order) and its local structure (pitch of individual syllables). We found that birds matched the pitch of syllables to the most acoustically similar target in the tutor song, regardless of global context, resulting in an intermediate-stage song in which the correct syllables were sung in the wrong order. These results refute a sensory-motor learning mechanism where a target song memory is recalled by temporal order, and suggest that instead, parts of the song memory are recalled in a motor driven way, according to their similarity to sung syllables. Consequently, two distinct mechanisms are required to accomplish the learning of a vocal sequence: 1. Local matching of the acoustic structure of individual units in the sequence; and 2. Global matching of sequence order. Our results present the first experimental evidence of how an internal sensory template is used to guide the development of the motor program for song.