Past events

The goal of perceptual systems is to provide useful knowledge about the environment and to encode this information efficiently. As such, perception is an active process that often involves the movement of sense organs such as the eyes. This active nature of perception has typically been neglected in current theories describing how nervous systems learn sensory representations. Here we present an approach for intrinsically motivated learning during active perception that treats the learning of sensory representations and the learning of movements of the sense organs in an integrated manner. In this approach, a generative model learns to encode the sensory data while a reinforcement learner directs the sense organs so as to make the generative model work as efficiently as possible. To this end, the reinforcement learner receives an intrinsic reward signal that measures the encoding quality currently obtained by the generative model. In the context of binocular vision, the approach is shown to lead to a self-calibrating stereo vision system that learns a representation for binocular disparity while at the same time learning proper vergence eye movements to fixate objects. The approach is quite general and can be applied to other types of eye movements such as smooth pursuit movements during motion perception. It may also be extended to different sensory modalities. Somewhat surprisingly, the approach also offers a new perspective on the development of imitation abilities.

Understanding the neural circuitry underlying addictive behavior is essential as a first step towards treating addiction. The nucleus accumbens and the ventral pallidum are two interconnected regions known to mediate reward-related behavior. Using a multidisciplinary approach I describe synaptic changes in both regions following exposure to cocaine. However, the connectivity patterns between these regions and how specific projections are affected by drugs of abuse remain elusive. In an attempt to elucidate the nature of these connections I will show preliminary results calling for a re-examination of the current thinking about accumbal inputs to the ventral pallidum. Future work will engage in describing how these pathways are differentially changed in drug addiction.

Brain oxytocin has been repeatedly shown to exert anxiolytic effects and to inhibit the activity of the HPA axis. These acute effects are mediated via activation of hypothalamic oxytocin receptors, which are GPCR, and subsequently of the MAPK pathway. In order to establish oxytocin as a potential psychotherapeutic option, effects of chronic neuropeptide treatment need to be studied. Chronic intracerebral infusion of oxytocin over 2 weeks dose-dependently increased anxiety-related behaviour and reduced oxytocin receptor binding within relevant brain regions. Thus, before oxytocin can be considered a therapeutic option to treat patients suffering from, for example, autism, schizophrenia, social phobia or drug addiction, thorough investigations are needed to reveal alterations of the endogenous oxytocin system. However, application of the low dose of oxytocin to male mice during 3-weeks exposure to an established chronic psychosocial stress paradigm - the chronic subordinate colony housing - attenuated the adverse chronic stress effects on immunological, physiological and emotional parameters further supporting ist stress-protective properties. http://www.uni-regensburg.de/biologie-vorklinische-medizin/neurobiologie-tierphysiologie/team-mitarbeiter/prof-dr-inga-d-neumann/index.html

Insects are an inexhaustible source for scientists who desire to inspire ideas, processes, structures and functions from biology and implement them into engineering, specifically those interested in locomotion and in the improvement of robot mobility. Novel insights are offered based on a collaborative and combined approach that includes high-speed video monitoring of behavior, electrophysiological recordings of nerves and muscles activity, mathematical modeling and computer simulations. An overview will be presented of several different research projects focusing on cockroach running, caterpillar crawling (soft robotics), locust jumping, flight (remote control), and swarming.

Much of what we know about how neurons interact and form ensemble activity patterns comes from recordings in cell cultures, brain slices, and anesthetized animals, yet dynamics in the intact brain of a behaving animal might differ. I will describe an approach to the study of local circuit dynamics in freely-moving animals, namely the combination of high-density extracellular recordings coupled with multi-site/multi-color optogenetic stimulation, combined with in-vivo pharmacology. This approach, applied to the rodent neocortex and hippocampus, yielded surprising insight into mechanisms of multiple phenomena, including spiking regime resonance, the generation of high-frequency oscillations, and spike phase precession.

Retinal degenerative diseases, such as Retinitis Pigmentosa (RP) and Age related Macular Degeneration (AMD), lead to loss of sight due to degeneration of photoreceptors, yet the inner retinal neurons which process the visual signals and relay them to the brain are relatively well preserved. Patterned electrical stimulation of the inner retinal neurons can elicit patterned visual perception, thereby restoring sight to some degree, as was demonstrated in recent clinical trials. However, current RF-powered implants require bulky electronics and trans-scleral cables, making implantation very complex and prone to failures. Even more importantly, low visual acuity achieved with the current implants limits their applicability to very small fraction of patients. We have developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Implants with pixel sizes of 280, 140 and 70µm were successfully implanted in the subretinal space of wild type and degenerate rats, and elicited robust cortical responses (eVEP) upon stimulation with NIR light. Amplitude of the eVEP increased with peak irradiance and pulse duration, and decreased with frequency in the range of 2-20Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases. Activation of the retinal bipolar cells by the implant makes our model a unique tool for studying retinal circuitry by comparing the response to stimuli elicited by the subretinal implant to those naturally elicited by visible light. I will discuss our novel approach to quantitative assessment of the visual acuity provided by the implant, as well as some unique aspects of prosthetic vision, such as stroboscopic stimulation. The theoretical and practical limits of visual acuity will be discussed along with future directions for restoration of sight to the blind.