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Armin Bahl Smarter than One Might Think: Drosophila as a model for higher cognitive functions In the fruit fly Drosophila melanogaster, electrophysiological and imaging techniques as well as neuronal genetic modifications can be combined at the same time in the behaving animal. It is that recent fusion of well-established toolsets that makes the fly one of the most popular model organisms for the study of developmental biology, brain physiology, neuronal computation and behavior today (Olsen & Wilson, 2010, Seelig et al., 2010). The Drosophila brain has less than a cubic square millimeter in size and approximately 300.000 nerve cells. Brains of higher organisms like humans have more than 300.000 times more nerve cells and are more than 2 million times larger. These numbers could lead to the belief that the fly’s behavioral repertoire should be small and of only minor interest for human neurobiology. But despite their small brains flies do have amazing abilities, they possess, for example, an elaborated memory and can be trained to associate colors with objects or odors (Brembs & Heisenberg, 2001). Using visual cues they also build up spatial memories allowing them to quickly navigate towards a target spot whose location had be learned before (Foucaud et al., 2010). A well-studied topic in psychophysics is attention and saliency, which is normally attributed only to higher organisms but it was shown that the ability to attend to a salient object is also present in flies (Wolf & Heisenberg, 1980). There is an ongoing debate on whether the freedom of will might be an illusion and that behaviour instead of being self-initiated is always deterministic with variability coming from internal or external noise (Heisenberg 2009). However there are evidences from research in Drosophila that the manoeuvres during flight might be self-initiated by internal noise-independent mechanisms (Maye et al., 2007). These examples demonstrate that Drosophila has a long list of exciting and elaborated abilities and therefore makes it an interesting model organism also for research in human cognition, physiology and psychology. In combination with the experimental possibilities in flies it is now possible to tackle the neural basis of these behaviors which might shed light on the neural representation of learning, attention and will - might it be free or not. Arun Singh Meditation…? Questions for Neuroscientists Generally, the aim of meditation is modulation of awareness. Any effort free from distraction of the mind may work as effective meditation. There are two different meditation categories: concentrative, and non-concentrative. It may be integrated into a specific spiritual context, but is by itself not specific to religion in general. It includes an approach to manage stress, anxiety, headache, and daily physical pain complaints. Since 1960, more than 1000 research articles have been published trying to explain the benefits of meditation. Richard Davidson and Dalai Lama have investigated the effects of meditation on the brain. For example, one of Davidson’s studies found that long-term meditators showed high amplitude gamma synchrony during mental practice. All of his studies imply that intensive meditation results in both functional as well as structural changes in the brain regions. Investigations performed by Lazar et al have demonstrated that mediation can increase the density of grey matter and cortical thickness. Meditation has also been related to alterations of sensory perception, as well as metabolic changes, e.g. of heart rate, blood pressure, respiration. Given scientific evidence has proved to be beneficial for mental and physical health, but there is much more left to be yet understood by neuroscientists. 8
Barbara Trattner Optogenetics Optogenetics is an elegant emerging method in neuroscience, which exploits optical and genetic tools to precisely control neuronal brain circuits in living animals at a high temporal and spatial resolution. Generally neuronal properties are investigated with the help of selective pharmacological agents targeting certain neuronal structures. These agents are however disadvantageous in that they have a systemic action, are temporally imprecise and may cause unspecific side-effects. In addition to replacing pharmacology, optogenetic approaches can also substitute electrical stimulation of a neuronal population for defined light-gated activation. Photosensitive proteins can be artificially expressed in neurones to alter their firing properties and thereby information processing. By exposing only a certain brain area to light, only the activity of those neurones will be modulated by the photosensitive proteins. Due to the immense possibilities that optogenetics offer in elucidating neuronal brain circuits, it was selected the method of the year 2010 by the prestigious scientific journal Nature Methods. The principle of using optogenetics was first found around 2000, when photosensitive proteins were expressed in neurones, which could thereby be sensitised to light. Further research in the field of optogenetics led to the implementation of genetically-encoded bacterial and algeal photosensitive ion channels and pumps in neurones. Depending on the properties of these ion transporters, they can either hyperpolarise or depolarise neurones. An advantage of using photosensitive ion transporters to targeting endogenous channels with drugs is the fast time constant: Upon illumination with the correct wavelength, photosensitive channels open and close in the range of milliseconds. A lot of research is currently going on to develop new artificial light-gated ion channels or receptors. With the help of tissue-specific promoters, these proteins can be expressed only in a certain neuronal subgroup or at a confined developmental stage. Precisely choosing the brain area, which is exposed to light, allows the further refinement of the subgroup of modulated neurones. By expressing photosensitive proteins in a subclass of neurones responsible for a defined behaviour, researchers can nowadays control behaviour by exciting or inhibiting only those neurones with light. Flies for instance can learn that a certain odour is aversive when the odour is paired with the lightgated activation of a certain receptor class. Mice can be woken up when a certain neuronal population of the hypothalamus, artificially expressing photosensitive proteins, are stimulated with light. The therapeutic aim of optogenetics for humans is to restore vision after a degeneration of photoreceptor cells in the retina. In mice it was shown that equipping retinal neurones with photosensitive proteins from microbes using a viral delivery can restore visual responses. In humans this approach is currently investigated in inherited retinal dysfunctions: In Leber’s congenital amaurosis patient lack a certain pigment protein of the retina. Subretinal administration of viral vectors encoding the absent pigment, lead to a long-lasting improvement in vision perception. However optogenetic treatments are not yet standard in the therapy of blindness, mainly due to the fact that viral gene transfer bears many risks. 9
Page 1: ISSUES IN PHILOSOPHY AND NEUROSCIEN
Page 4 and 5: PANEL 1: CONSCIOUSNESS I Program Mo
Page 6 and 7: Wedesday, April 19 th PANEL 6: WILL
Page 10 and 11: Bianca van Kemenade Multisensory In
Page 12 and 13: David Kaufmann Neuroscientific Rese
Page 14 and 15: Georgina Torbet Cognitive Neuroscie
Page 16 and 17: Ryszard Auksztulewicz Recurrent Neu
Page 18 and 19: Smadar Ovadia-Caro Reduction of Int
Page 20 and 21: Berlin Faculty List of participants

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