Completed Projects
Project A3 (Hatt)
Funding period 1 (2010/2 – 2014/1)
Molecular and Cellular Mechanisms of Chemoperception in the Mammalian Trigeminal System
Summary
Combining molecular biology with live cell imaging and electrophysiological techniques, we will study the trigeminal system of rat in vitro and in vivo. In primary cell cultures of trigeminal ganglion neurons we will identify and functionally characterize molecular players participating in odor and astringency perception using calcium imaging and patch clamp recordings. The results from this part of the project will shed light on the molecular mechanisms of peripheral trigeminal perception. Next we will transfer our results obtained from in vitro studies to the in vivo situation in the intact trigeminal ganglion of rat. We already established a preparatory approach that allows extracellular electrical recordings of neuronal activity and an high resolution of optical signals arising from the intact rat trigeminal ganglion by imaging technology. Using voltage-sensitive dyes we will analyze whether stimulus specific spatiotemporal activation patterns exist at the level of the trigeminal ganglia. These results may not only be important for a better understanding of trigeminal chemoperception but should in general help to expand our knowledge about information processing in peripheral nervous systems.
Prof. Dr. mult. Hanns Hatt
Cellphysiology
Faculty of Biology and Biotechnology
Ruhr-Universität Bochum, ND 4
e-mail
Phone: +49 – (0)234 – 32 – 26792
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Project A4 (Funke)
Funding period 1 (2010/2 – 2014/1)
Experience-Dependent Plasticity of Sensory Processing in an Experimentally Modified Cortical Network of Rat Barrel Cortex
Summary
Cortical integration and representation of sensory information via receptive field (RF) organization of single neurons and functional map topography built by neuronal populations are not only a matter of excitatory divergence and convergence but are substantially controlled by diverse inhibitory systems. In this project, we will investigate how RF properties and sensory map (re-)organization of the rat barrel cortex is regulated by a particular type of GABAergic neuron, namely the parvalbumin-expressing neurons that are believed to comprise fast-spiking (FS) interneurons.
We will also investigate the importance of the activity-regulating, calcium-binding protein parvalbumin. According to their high-frequency, non-adapting firing behavior and the perisomal termination of their synapses, the PV-positive neurons are thought to control, and temporally shape, the output activity of pyramidal cells. Loss of PV-expression, or loss of PV-expressing neurons is accompanied by changes in cortical excitability (including increased susceptibility for seizures), changes in gamma oscillations and changes in short-term synaptic plasticity. FS-neurons within the barrel cortex receive thalamocortical feed-forward and pyramidal cell feed-back input within layer IV (and partly L II/III) and are thus at a cardinal position to modulate the spatial aspects of cortical RFs via lateral inhibition, and the temporal integration of activity within network (cell assembly) via recurrent inhibition.
To study the specific contribution of PV-positive neurons to cortical processing of sensory information and its use-dependent plasticity, it would be ideal if one could acutely switch off the activity of these neurons. In recent experiments we found that repetitive high-frequency stimulation, applied either by transcranial magnetic stimulation (rTMS) or by intracortical microstimulation (ICMS), initiates a fast (within 1-2 h), strong (>50%) and lasting (up to 7 days) reduction in cortical parvalbumin and in part GAD67 expression, a sign of weakened activity of these neurons. We will use these tools to acutely disturb the activity of these neurons and to investigate their contribution to receptive field structure, temporal integration of sensory activity, use-dependent plasticity of the topographic map of whisker representation in the rat barrel cortex and the associated changes in plasticity-related protein expression.
Prof. Dr. Klaus Funke
Neurophysiology
Medical Faculty
Ruhr-Universität Bochum, MA 3
e-mail
Phone: +49 – (0)234 – 32 – 23944
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Project A9 (Krieger)
Funding period 2 (2014/2 – 2018/1)
Investigation of cortico-subcortical dynamics in sensorimotor integration
Summary
Behaviour, guided by sensory stimuli, depends on the interplay between movements of the sensory organ, cortical processing, and finally motor output that can cause adjustment of body position and sensory organ movements. This sensory-motor-sensory loop is dynamically regulated by cortical control of sub-cortical structures. Using the rodent somatosensory cortex as a model system, we analyze the importance of cortical projections to brain areas involved in sensory-guided behavior, including specifically cortical responses to optimize detectability of sensory stimuli.
Prof. Dr. Patrik Krieger
Systems Neuroscience
Medical Faculty
Ruhr-Universität Bochum, MA 3 / 148
e-mail
Phone: +49 – (0)234 – 32 – 23898
Fax: +49 – (0)234 – 32 – 14082
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Project B6 (Bellebaum)
Funding period 1 (2010/2 – 2014/1)
Does the neural representation of new objects in semantic memory reflect object-related sensory experience?
Summary
An ongoing debate in cognitive neuroscience is concerned with the question how the stimuli in our environment are categorized and how they are represented in the brain. Selective loss of semantic knowledge affecting the categories “living” or “non-living”, observed in brain-lesioned patients, suggests that the entities in semantic memory are organized in a category-specific way. The so called modality-specific account of semantic memory organization states that the brain representation of knowledge about different entities of semantic memory reflects the degree to which different sensory systems contributed to knowledge acquisition about the entity in question. The proposed project aims to investigate the role of object-related sensory experience for object representations in semantic memory. More specifically, it will be examined, if qualitatively different types of sensory experience lead to qualitatively different semantic memory representations for new, unknown objects. In the first part of the project the main emphasis will be on the comparison of tactile manipulative and visual object related information. Another main aim of the proposed project is to elucidate, in how far the observation of object manipulation induces object representations in action related brain regions, similar to the representations induced by active object manipulation. The final phase will be dedicated to studying the integration of two modalities in semantic memory representations.
Prof. Dr. Christian Bellebaum
Biological Psychology
Heinrich-Heine-Universität Düsseldorf
Project B8 (Suchan)
Funding period 1 and funding period 2 (2010/2 – 2018/1)
Integration of sensory and memory processing in the human medial temporal lobe
Summary
This project investigates if the medial temporal lobe is involved in perceptual processing, in addition to its well-known role in long-term memory. First results from our lab support this idea, but could not show a specialization of the hippocampus for spatial processes that complement a role for the perirhinal cortex in object-related perceptual processes. We will clarify the exact conditions of medial temporal lobe involvement in perceptual processes and the differentiation of this process from phenomena such as incidental encoding or working memory.
Prof. Dr. Boris Suchan
Clinical Neuropsychology
Neuropsychology
Institute of Cognitive Neuroscience
Faculty of Psychology
Ruhr-Universität Bochum, IB 6 / 181
e-mail
Phone: +49 – (0)234 – 32 – 27575
Fax: +49 – (0)234 – 32 – 14622
Homepage
Project B9 (Sauvage)
Funding period 2 (2014/2 – 2018/1)
Medial temporal lobe structures underlying sensory information processing during memory retrieval
Summary
A current major controversy in recognition memory comprises whether the neural substrate for familiarity for sensory information is the parahippocampal region of the brain, or whether the hippocampus also supports this process. In addition, it remains unclear whether different parts of this region are recruited when different type of sensory modalities are involved. In the present proposal, we explore whether familiarity is exclusively supported by some of the parahippocampal regions: the perirhinal and lateral entorhinal cortices, and whether using odor or object-based tasks alters the pattern of brain activation observed in models of familiarity-only judgements, with and without functional hippocampal involvement. To do so, we will combine behavioural and functional neuroanatomical techniques as well as structural magnetic resonance imaging in rats.
Prof. Dr. Magdalena Sauvage
Department Functional Architecture of Memory
Leibniz Institute for Neurobiology
Brenneckestraße 6
39118 Magdeburg
e-mail
Phone: +49 – (0)391 – 6263 – 94011
Homepage