Projects

Project leader

Prof. Dr. Mark W. Greenlee

Project members

Prof. Dr. Anton Beer, N. N.

Funding period

01.12.2018 – 31.12.2021

Renewal period

01.11.2024 - 31.10.2027

DFG-Projekt "Neural correlates of perceptual filling-in"

Project leader??????????????????????????????????????????????????????????????

Dr. Mark W. Greenlee

Project members

Yih-Shiuan Lin (in cooperation with Prof. Dr. C.C. Chen, NTU Taipei)

Funding period

01.07.2022 – 30.06.2025

Objectives

Filling-in is the perceptual tendency of an observer to perceive a continuous visual pattern even when it is interrupted by a small "blank" area. Filling-in occurs at the blind spot, but also in scotomatous regions in patients with diseases of the visual pathways. Because filling-in occurs in an "empty" region, there is no physical stimulus to elicit a response in the visual cortex at this retinotopic location. Observers are usually asked to report on a trial when they experience filling-in. Neural responses to stimuli with and without filling-in can be compared to determine whether these responses differ on these two types of trials. Machine learning can be used to determine whether a classifier can distinguish between these two types of events. In univariate analysis, we found no difference between BOLD activation with and without filling-in. However, using a leave-one-out training procedure and a support vector machine, it was possible to classify percepts based on activation differences in early visual cortex (Lin, et al. 2020). We developed a paradigm to assess the presence or absence of filling-in. Observers are presented with periodic patterns of empty areas that serve as an artificial scotoma. By presenting a test stimulus in the empty region after filling-in has occurred, we can measure the neuronal response to the test stimulus and determine whether this response is affected by the presence of filling-in. The test stimulus will elicit a large enough neuronal response to allow reliable measurement of neuronal activity. We will vary the contrast of the test stimulus to determine the contrast transfer function in the presence of the eliciting stimulus. This will allow us to determine the contrast transfer function in response to the test stimulus. Variations in the physical properties of the eliciting stimulus and the test stimulus will be performed to separate response components attributable to these two types of stimuli, respectively.In a series of three studies, we will parametrically measure the response functions to the test stimulus using functional magnetic resonance imaging (fMRI), event-related potentials (ERP), and psychophysical experiments. The latter are performed to determine the range of action of the basic phenomena. The fMRI experiments will precisely identify the brain areas for filling-in. This precision is required because the area in the visual cortex considered to be the correlate for filling-in, V2, is small. The ERP trials will determine the temporal dynamics of the stimulus response with respect to the onset of filling-in. A model will be further tested to develop a new theory of filling-in.

(German) Filling-in ist die Wahrnehmungstendenz eines Beobachters, ein kontinuierliches visuelles Muster wahrzunehmen, selbst wenn dieses durch einen kleinen ?leeren“ Bereich unterbrochen ist. Filling-in tritt am blinden Fleck auf, aber auch in skotomat?sen Regionen bei Patienten mit Erkrankungen der Sehbahnen. Da das Filling-in in einer ?leeren“ Region auftritt, gibt es keinen physikalischen Reiz, der eine Reaktion im visuellen Kortex an dieser retinotopen Stelle ausl?st. Die Beobachter werden in der Regel aufgefordert, in einem Versuch zu berichten, wann sie das Filling-in erleben. Die neuronalen Reaktionen auf Stimuli mit und ohne Filling-in k?nnen verglichen werden, um festzustellen, ob sich diese Reaktionen bei diesen beiden Versuchsarten unterscheiden. Mit Hilfe von maschinellem Lernen kann ermittelt werden, ob ein Klassifikator zwischen diesen beiden Ereignistypen unterscheiden kann. Bei der univariaten Analyse fanden wir keinen Unterschied zwischen der BOLD-Aktivierung mit und ohne Filling-in. Mit einem Leave-One-Out-Trainingsverfahren und einer Support-Vector-Maschine war es jedoch m?glich, die Wahrnehmungen anhand der Aktivierungsunterschiede im frühen visuellen Kortex zu klassifizieren (Lin, et al. 2020). Wir entwickelten ein Paradigma , um das Vorhandensein oder Nichtvorhandensein von Filling-in zu beurteilen. Den Beobachtern werden periodische Muster mit leeren Bereichen pr?sentiert, die als künstliches Skotom dienen. Indem wir einen Testreiz in der leeren Region pr?sentieren, nachdem das Filling-in aufgetreten ist, k?nnen wir die neuronale Reaktion auf den Testreiz messen und feststellen, ob diese Reaktion durch das Vorhandensein des Filling-in beeinflusst wird. Der Testreiz wird eine ausreichend gro?e neuronale Reaktion hervorrufen, um so eine zuverl?ssige Messung der neuronalen Aktivit?t zu erm?glichen. Wir werden den Kontrast des Testreizes variieren, um die Kontrastübertragungsfunktion in Anwesenheit des ausl?senden Reizes zu bestimmen. 百利宫_百利宫娱乐平台￥官网 erm?glicht uns, die Kontrastübertragungsfunktion als Antwort auf den Testreiz zu bestimmen. Variationen der physikalischen Eigenschaften des ausl?senden Reizes und des Testreizes werden durchgeführt, um Antwortkomponenten zu trennen, die jeweils diesen beiden Reizarten zuzuordnen sind.In einer Serie von drei Studien werden wir die Antwortfunktionen auf den Testreiz mit funktioneller Magnetresonanztomographie (fMRI), ereigniskorrelierten Potentialen (ERP) und psychophysischen Experimenten parametrisch messen. Letztere werden durchgeführt, um den Wirkungsbereich der Grundph?nomene zu ermitteln. Die fMRT-Experimente werden die Hirnareale für das Filling-in pr?zise identifizieren. 百利宫_百利宫娱乐平台￥官网e Pr?zision ist erforderlich, da das Gebiet im visuellen Kortex, das als Korrelat für das Filling-in gilt, V2, klein ist. Die ERP-Versuche werden die zeitliche Dynamik der Reizantwort in Bezug auf den Beginn des Filling-in bestimmen. Ein Modell wird weiter getestet, um eine neue Theorie des Filling-in zu entwickeln.

Reference

Lin, Y.-S., Chen, C.-C., and Greenlee, M. W. (2020). Lateral modulation of orientation perception in center-surround sinusoidal stimuli: Divisive inhibition in perceptual filling-in.?Journal of Vision,?20(9), 5–5. doi.org/10.1167/jov.20.9.5

DFG-Projekt "Magnetic Resonance Imaging of Neural Plasticity in the Visual Cortex of Patients with Central Vision Loss: Effects of Long-term Adaptation and Training"

Project leader ?????????????????????????????????????????????????????????????

PD Dr. Tina Plank, Prof. Dr. Mark W. Greenlee

Project members

M.Sc. Edith Benkowitsch (in cooperation with Prof. Dr. med. Herbert J?gle, University Eye Hospital)

Funding period

01.07.2021 – 30.06.2024

Objectives

Retinal diseases such as macular degeneration usually lead to central vision loss, making the affected patients dependent on their peripheral residual vision. Often a kind of pseudo fovea (preferred retinal locus, PRL) develops in the peripheral visual field, which is then used in everyday life for the fixation of objects or faces, as well as for reading. These long-term adaptation processes are accompanied by certain neuroplastic changes in the visual cortex of the affected patients. Furthermore, appropriate training protocols, such as visual perceptual learning tasks, can help to further improve peripheral visual performance and even trigger neuronal plasticity. Our goal in this project is to investigate how these two neuroplastic processes of long-term adaptation and training act together and to uncover possible interrelations between the two. For this purpose, visual perceptual learning in the peripheral visual field will be applied, and it will be examined to what extent the learning success at the PRL of patients with central vision loss will be different from the learning success at a comparable peripheral site in the opposite visual hemifield (OppPRL) and from the learning success of normally sighted control persons, who are trained in the same visual task. The training measures will be accompanied by (functional) magnetic resonance imaging (fMRI) to reveal the neural correlates of learning in the visual cortex. Additionally, the biochemical changes caused by learning will be determined by magnetic resonance spectroscopy (MRS). To investigate possible changes in the cortical macro- and microstructure in grey and white matter of the visual cortex, structural and diffusion-weighted MRI will be performed. These measures will provide us with a more comprehensive picture of long and short term neuroplastic adaptation processes in patients with central vision loss and thus help to design even more efficient training protocols.

(German) Magnetresonanztomographie der neuronalen Plastizit?t im visuellen Kortex von Patienten mit zentralem Sehverlust: Effekte der langfristigen Anpassung und des Trainings

Netzhauterkrankungen wie Makuladegeneration führen meist zu zentralen Gesichtsfeldausf?llen, wodurch die betroffenen Patienten auf ihr peripheres Restsehverm?gen angewiesen sind. H?ufig entwickelt sich daraufhin im peripheren Gesichtsfeld eine Art Pseudo-Fovea (preferred retinal locus, PRL), die dann im Alltag zur Fixation von Objekten bzw. Gesichtern genutzt wird, sowie beim Lesen eingesetzt wird. 百利宫_百利宫娱乐平台￥官网e langfristigen Anpassungsprozesse gehen mit gewissen neuroplastischen Ver?nderungen im visuellen Kortex der betroffenen Patienten einher. Des Weiteren k?nnen geeignete Trainingsprotokolle, wie z.B. visuelle perzeptuelle Lernaufgaben, helfen, die periphere Sehleistung weiter zu verbessern, und selbst neuronale Plastizit?t ansto?en. Unser Ziel im Rahmen dieses Projektes ist es, das Zusammenwirken dieser beiden neuroplastischen Prozesse der langfristigen Anpassung und des gezielten Trainings zu untersuchen und m?gliche Wechselwirkungen zwischen beiden aufzudecken. Hierzu soll visuelles perzeptuelles Lernen im peripheren Gesichtsfeld eingesetzt werden und überprüft werden, inwiefern sich der Lernerfolg am PRL von Patienten mit zentralem Gesichtsfeldausfall vom Lernerfolg an einer ?hnlich peripheren Stelle im gegenüberliegenden Gesichtsfeld (OppPRL) und vom Lernerfolg normalsichtiger Kontrollpersonen unterscheidet, die in derselben visuellen Aufgabe trainiert werden. Die Trainingsma?nahmen sollen von (funktionellen) Magnetresonanztomografie (fMRT)-Messungen begleitet werden, um die neuronalen Korrelate des Lernens im visuellen Kortex aufzudecken. Zus?tzlich sollen die biochemischen Ver?nderungen durch das Lernen mittels Magnetresonanzspektroskopie (MRS) ermittelt werden. Um m?gliche Ver?nderungen in der kortikalen Makro- und Mikrostruktur in grauer und wei?er Substanz des visuellen Kortex zu untersuchen, sollen strukturelle und diffusionsgewichtete MRT-Aufnahmen durchgeführt werden. Die genannten Ma?nahmen k?nnen uns ein umfassenderes Bild über lang- und kurzfristige neuroplastische Anpassungsvorg?nge bei Patienten mit zentralem Sehverlust liefern und so dabei helfen, noch effizientere Trainingsprotokolle zu entwerfen.

Contact

PD Dr. Tina Plank
tina.plank@ur.de
University of Regensburg

Institute for Experimental Psychology
93040 Regensburg, Germany
Tel: +49 941 943 3849
Fax: +49 941 943 3233
/humanwissenschaften/psychologie-greenlee/team/plank/index.html

DFG-Projekt "Multisensorische Wahrnehmung der Eigenbewegung: Psychophysik und Funktionelle Neuroanatomie"

Project leader

Prof. Dr. Mark W. Greenlee

Project members

PD Dr. Anton Beer, M.Sc. Simon Wein

Funding period

01.12.2018 – 31.12.2021

Objectives

Our sensory systems allow us to experience our environment by the senses of touch, hearing, seeing, smell, and taste. Moreover, we have vestibular organs that inform us about self-motion and thus help us to keep our body in balance. In order to analyze the interactions between the visual and vestibular sensory systems for the sensation of self-motion, we will combine the method of caloric vestibular stimulation with visual stimulation. We want to use these stimulation types in order to investigate the neural interactions during simulated self-motion. Therefore, congruent and incongruent stimulus combinations will be applied in order to investigate their effect on the perception of self-motion, detecting its direction, and the relevant neural correlates of self-motion perception. We will assess the brain activity of healthy volunteers with the method of functional magnetic resonance imaging (fMRI). Moreover, we will apply the method of diffusion-weighted MRI combined with probabilistic fiber tracking in order to analyze the anatomical connecitivity between vestibular and visual cortical regions. By comparing structural and functional connectivity of the the human brain during rest (i.e., resting state) we want to show how parts of the visual-vestibular network are connected and how they interact with each other. Ultimately, we will also investigate the suppression of vestibular cortex during visual processing. If attention is directed towards visual motion stimuli, then activity in the vestibular cortex is suppressed. The method of repetitive transcranial magnetic stimulation (TMS) and functional MRI will be applied in order to determine the source of this inhibition in the vestibular cortex. The results of these studies will provide new insights into the multisensory integration of visual and vestibular information for the perception of self-motion.

Contact

PD Dr. rer. nat. Anton L. Beer?
anton.beer@ur.de
University of Regensburg
Institute for Experimental Psychology
93040 Regensburg, Germany
Tel: +49 941 943 3745?
Fax: +49 941 943 813745

DFG funded project "Neurokognitive Mechanismen der Graphem-Farb-Syn?sthesie"(VO 1998/1-1)

Project leader

PD Dr. Gregor Volberg

Project members

Franziska Wei?, Anja Sch?ll

Funding period

01.11.2014 – 31.10.2017

Objectives

Synesthesia is a perceptual phenomenon where a stimulation in one sensory modality induces a concurrent sensation in a different modality or feature dimension that was not objectively stimulated. In this project we aim to identify the neuro-cognitive mechanisms of grapheme-color-synesthesia where written numbers or letters induce a concurrent sensation of color. Especially, we will investigate neural connectivity between grapheme and color processing brain areas and brain areas associated with visual-spatial selection. To this end, EEG experiments as well as combined EEG and fMRI studies will be conducted. The results of this project will improve our understanding of synesthesia and related topics in general psychology, like visual awareness or visual feature integration.

Contact

PD Dr. rer. nat. Gregor Volberg
gregor.volberg@ur.de
University of Regensburg
Institute for Experimental Psychology
93040 Regensburg, Germany
Tel: +49 941 943 3862
Fax: +49 941 943 3233
http://www.psychologie.uni-regensburg.de/Greenlee/team/volberg/volberg.html

DFG funded Research Unit 1075 "Regulation and Pathology of Homeostatic Processes for Visual Function"

Subproject 8 "Neuroplasticity in retinotopic visual cortex as a consequence of retinopathologies"

Project leader

Prof. Dr. Mark W. Greenlee

Project members of the 2nd period

Dr. Katharina Rosengarth, Markus Goldhacker, Sabine Brandl-Rühle (in cooperation with Prof. Dr. med. Horst Helbig, Director, University Eye Hospital)

Project members of the 1st period

Dr. Tina Plank, Jozef Frolo, Sabine Brandl-Rühle (in cooperation with Prof. Dr. med. Horst Helbig, Director, University Eye Hospital)

Funding period

since 2008

Objectives

This 3-year project uses functional MRI to determine the extent to which macular degeneration induces neuroplastic alterations in the visual cortex of the affected patients. We will compare the results of a group of 20 patients with a juvenile form of macular degeneration (JMD) to those of patients with age-related macular degeneration (AMD). Our main focus will deal with the issue whether oculomotor training in AMD patients, assisting them to establish a new preferred retinal locus (PRL) for eccentric fixation, can promote cortical reorganization. The results will provide important feedback for therapeutic gains in patients with AMD. They will help guide new training protocols, thereby improving the patients' experienced quality of life.

For more information see: http://www.uni-regensburg.de/FOR1075/index.htm

2022

Wein, Simon?(2022).

"Applications of Spatio-Temporal Graph Neural Networks for Brain Connectivity Analysis"

Lin, Yih-Shiuan?(2022).

"Lateral modulation, divisive inhibition, and neural mechanism of perceptual filling-in"

Tallon, Miles?(2022).

"Assessment of Visual Literacy – Contributions of Eye Tracking"

Tahedl, Marlene?(2022).

"Mapping abnormality: Towards evaluating MRI scans for individualized diagnosis and validation of clinical course/progression in motor neuron disease"

2019

Mohammadi Jooyandeh, Somayeh (2019).

"Pharmaco-fMRI Challenges before and after short-term Treatment of Major Depression with Escitalopram, Mirtazapine, Agomelatine or Placebo and the Relation to the Hypothalamus-Pituitary-Adrenal-Axis Activity"

Anna Maria Wirth (2019)

"Structural magnetic resonance imaging in amyotrophic lateral sclerosis "

2017

Goldhacker, Markus?(2017).

"Frequency-resolved Dynamic Functional Connectivity and Scale Stability of Connectivity States"

Frank, Sebastian (2017).

"The neural bases and behavioral characteristics of feature conjunction learning"

2016

Lehner, Astrid (2016).

?Repetitive transcranial magnetic stimulation for the treatment of chronic subjective tinnitus: Optimization of treatment effects“

Dissertation at the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

2014

Dodoo-Schittko, Frank (2014).

"Funktionelle Magnetresonanztomographie als Instrument zur Aufdeckunghemisph?rischer Dominanz, der Lokalisation und neuroplastischer Prozesse von Sprachfunktionen."

Dissertation at the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available at the Library of the University of Regensburg
under: 00/CZ 1320 D646. Further printed copies are also available at several German University libraries and at the German National Library (deutsche Nationalbibliothek).

Blurton, Steven (2014).

"Integration auditiv-visueller Reizinformation."

Dissertation at the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available online.

Zunhammer, Matthias (2014).

"Central modulators of human pain: Effects of oxytocin, exam stress, breathing exercises and transcranial magnetic stimulation."

Dissertation at the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg and the Institute of Psychiatry and Psychotherapy.

Manuscript available online.

2011

Fischer, Volker (2011).

"Analysis of connectivity between local multi-variate patterns of functional MRI data"

Dissertation at the Institute of Biophysics and Physical Biochemistry (supervisor Prof. Dr. E. W. Lang) in collaboration with the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available online.

Alichniewicz, Karolina (2011).

"Neuronale Korrelate der visuell-r?umlichen Informationsverarbeitungsprozesse bei Mild Cognitive Impairment"

Dissertation, University of Regensburg.

Manuscript available online.

2010

Heckel, Andreas (2010).

"Processing of pain and emotion in the human brain. An fMRI study"

Dissertation at the Institute of Psychiatry and Psychotherapy at the Medical Faculty (supervisor Prof. Dr. H. E. Klein) in collaboration with the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available online.

2009

Acs, Ferenc (2009).

"Neuronal dynamics of visual movement processing areas: A fMRI investigation of the connectivity of visual processing areas for motion processing and attention in the human brain"

Dissertation, University of Regensburg.

Manuscript available online.

Herpes, Martin (2009).

"Morphometrie cerebraler Ver?nderungen und psychophysische Erfassung olfaktorischer St?rungen bei Morbus Parkinson"

Dissertation at the Medical Faculty (supervisor Prof. Dr. U. Bogdahn) in collaboration with the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available online.

Rosengarth, Katharina (2009).

"Neuronale Korrelate grammatischer und semantischer Prozessierung bei Erwachsenen, Kindern und dysgrammatischen Kindern"

Dissertation at the Philosophic Faculty IV (supervisor Prof. em. Dr. H. Brekle) in collaboration with the Institute of Experimental Psychology (supervisor Prof. Dr. M. W. Greenlee), University of Regensburg.

Manuscript available online.

Frank, Gabriele (2009).

"Neurofunktionelle, neurostrukturelle und neuropsychologische Korrelate gesunden und pathologischen Alterns: der Einfluss des genetischen Risikofaktors ApoE epsilon4"

Dissertation, University of Regensburg.

Manuscript available online.

2007

Vallines García, Ignacio (2007).

"Modulation of neural activity in human visual cortex during saccade programming"

Dissertation, University of Regensburg.

Manuscript available online.

2006

Baumann, Oliver (2006).

"Kortikale Aktivierungsmuster auditiv-visueller Bewegungswahrnehmung w?hrend der Ausführung von Augenbewegungen und die Rolle des Neocerebellums in der Augenbewegungssteuerung"

Dissertation, University of Regensburg.

Manuscript available online.

Am Lehrstuhl besteht die M?glichkeit zur Betreuung von Abschlussarbeiten.

Eine Liste mit Themen bisher angefertigter Bachelor- und Masterarbeiten kann im Sekretariat angefordert werden.

DFG funded project "Integration of auditory-visual information" (GO 1855/1-1, GR 988/20-2)

Project leaders

Prof. Dr. Mark W. Greenlee, Dr. M. Gondan

Project members

Steven Blurton, Anja Wienbreyer

Funding period

01.04.2011 – 31.03.2013 (GR 988/20-2)

01.04.2009 – 31.03.2011 (GO 1855/1-1)

Objectives

We investigate basic mechanisms of integration of information provided by different sensory systems (e.g. auditory and visual). In basic speeded response tasks, participants receive either auditory information alone, visual information alone, or redundant information via both sensory modalities. Abundant evidence now exists that redundant information is pooled into a common channel (coactivation).? In our project we try to describe this process using a computational model (Diffusion Superposition Model, Schwarz, 1994, J Math Psychol): Based on the idea of simple additive superposition of channel activity, the model describes the reaction times observed in simple response tasks with redundant auditory and visual stimuli. In our project we investigate whether the model can equally explain reaction times observed in more complex tasks (Go/Nogo discrimination, choice reactions). Moreover, we manipulate task demands and spatial attention (e.g. Posner-task) to test whether the integration mechanism requires spatial attention. In an EEG study the computational model will be related to neurophysiological data.

DFG funded Research Unit 1097 "Person Perception Research Unit" (KO3918/1-1)

The temporal context of face perception

Project leader

G. Kovacs

Project members of the 1st period

Christian Walther, Daniel Kaiser, Iulia Lavric

Funding period

2010-2012

Objectives

A given picture of a person might look different at different times. The previous encounters with other people or in other words, the temporal context of a given face modify its perception. In our present proposal we will study the effect of previous experiences on face perception using psychophysical, electrophysiological and neuroimaging methods. In most of our planned experiments we will use the powerful paradigm of face adaptation (Kovács et al, 2006), leading to specific, high level aftereffects. In the first set of experiments we will study the similarities and differences of two immediate repetition related phenomena, priming and aftereffects. In a second series of experiments we will study how the variation of the statistical properties of preceding stimuli affects face perception. For this we will use matrixes of multiple faces. In the last set of experiments we will study perceptual decisions, related to faces. In particular, we will compare the effects of bottom-up bias (such as caused by face adaptation) and top-down biases (caused by directed selective attention or by prior predictive information) on perceptual decisions. Altogether our experiments will shed light on the mechanisms of implicit and explicit face representations and on the related decisions that are important in social settings during our everyday life.

BMBF funded Network "Perceptual Learning" (01GW0761)

Subprojects 1, 4 "Brain plasticity and perceptual learning: Experimental analysis and computational modeling"

Project leader

Prof. Dr. Mark W. Greenlee

Project members

Dr. Katharina Rosengarth, Markus Goldhacker

Funding period

01.01.2008 - 30.06.2011

Objectives

"Perceptual Learning" is a BMBF network funded in the platform "Research collaborations on cognitive performance and relevant disorders in humans".

This collaborative research effort aims to explore the neural mechanisms underlying cortical plasticity in healthy subjects and in patients who learn or re-learn a perceptual task. Our approach is novel since it is strongly guided by methods from computational and cognitive neurosciences and directly applies them to problems arising in clinical neurology and neurorehabilitation. In the experimental part of the project, we plan to employ prototypical tasks that can be learned within a few hours or at most a few days with repeated practice. Before and after this extensive training, our participants will take part in functional and anatomical MR-scan sessions. We will ask the subjects to perform a task for the first time (e.g., speed discrimination of transparent motion). After a sufficient training period, the participants will be scanned again on the same task. We will then compare the MR-correlates of brain structure, brain activation, brain connectivity and neural information processing before and after this training (Project Greenlee).

Furthermore, we plan to examine patients with retrochiasmatic injury and homonymous visual field loss with respect to their global processing capacity in scene perception and in reading at the behavioural-neuropsychological and the functional-neurobiological level. To gain more insight into the neuronal processes underlying neuronal plasticity in adults, fMRI and neuropsychological studies will be conducted before and after an oculomotor training program in patients recovering from posterior infarctions and/or cerebral haemorrhaging (Project Zihl). The results of these basic and clinical investigations will be modelled with mean-field theory and computational models to get a better quantitative description of the neural processes underlying perceptual skill acquisition and reacquisition after brain damage (Projects Neumann, Lang, Deco). Powerful novel data-analysis techniques for functional MRI data will be developed and applied to enhance our ability to extract specific correlates of neuronal plasticity during neurorehabilitation.

A further aim of the research group is to gain a better understanding of how learning takes place in low-level sensory and sensorimotor circuits and compare these processes with those occurring in high-level cognitive learning. Some of the projects will focus on the low-level perceptual learning that occurs when healthy volunteers learn a new task. What changes take place in the brains of adults when they learn a new sensory or sensorimotor task? Moreover, we are interested in the brain changes that take place when patients recover from brain damage. At the macroanatomical level, the neural basis of “scaffolding” processes (Petersson, 1998), where additional brain circuits are temporally recruited to perform supplementary processing during the recovery period, will be investigated. At the microanatomical level, spike timing dependent plasticity (Masquelier and Thorpe, 2007) will be incorporated into models of higher-level motion processing required for velocity discrimination. It remains to be determined how exactly both these macro- and microanatomical changes take place. Finally, we hope to provide clinicians with new imaging approaches and diagnostic tools to map changes in grey and white matter that accompany neural learning processes.

BMBF funded Network "Visuo-spatial Cognition"

Subproject 3 "Neural correlates of visual and memory-guided saccades during visual search" (01GW0653)

Project leader

Prof. Dr. Mark W. Greenlee

Project members

Volker Fischer, Markus Raabe

Funding period

01.01.2007 - 30.06.2010

Objectives

"Visuo-spatial Cognition" is a BMBF network funded in the platform "Cognition research".

The goal is to model and analyze brain mechanisms underlying spatial cognition during visual search and visual exploration. A total of 4 German laboratories are collaborating on this project.

Chair funded projects "Neurodegeneration"

Visuo-spatial information processing in patients with amnestic mild cognitive impairment (aMCI)

Karolina Alichniewicz, Florian Brunner, Helmut Nebl, Dr. Hans-Hermann Klünemann, Prof. Dr. Mark W. Greenlee

This study aims at exploring visuo-spatial information processing in healthy elderly and patients with amnestic mild cognitive impairment (aMCI). Participants undergo an extensive behavioral test battery with the main focus on working memory and attention. Subjects also participate in a pro-/anti-saccade task. With the help of two fMRI experiments we plan to investigate the neural correlates of cognitive processes relevant for working memory and saccadic control and to detect altered/compensatory brain activation patterns in aMCI patients.

In addition the project explores possible benefits of a short-term nordic walking program for aMCI patients and its impact on cognitive performance in behavioral tests as well as on neural brain activation.

Olfactory BOLD-reactions in patients with Parkinson's disease

Carolin M??nang, Gabriele Frank, Dr. Beate Winner, Prof. Dr. Jürgen Winkler, Prof. Dr. Mark W. Greenlee

Recent studies (e.g. Albers et al., 2006; Masaoka et al., 2007) point to the fact that already in early stages of Parkinson's disease (PD) the olfactory system shows distinct impairments additional to the well known pathological alterations in the basal ganglia. By presenting sniffing sticks as olfactory stimuli to 15 PD-patients and 15 age-matched healthy controls during the fMRI-session in a 3-Tesla-Scanner we will investigate the underlying neurofunctional correlates of this olfactory impairments. We hope to get new insights in the neuropathological processes of Parkinson's disease and to contribute to an effective and reliable diagnostic in early stages of this disease.

Neurofunctional and neuropsychological correlates of pathological ageing: mild cognitive impairment (MCI) and the impact of the genetic risk factor APO E epsilon4

Gabriele Frank, Stefanie Feuerer, Dr. Hans-Hermann Klünemann, Prof. Dr. Mark W. Greenlee

This study deals with the neurofunctional correlates of an important aspect of semantic memory, the recognition of the faces of famous people in MCI-patients, age-matched controls and young healthy subjects by conducting an fMRI experiment (3-Tesla-Scanner). Because it is well known that Apolipoprotein E epsilon4 (APOE epsilon4) is an important genetic risk factor for the development of Alzheimer's disease, a main focus of our study lies on the impact of the APOE status on cortical activation as well as neuropsychological performance of the subject groups mentioned above.

EU FP6 IST Cognitive Systems Integrated Project "Decisions in Motion" (FP6 Project 027198)

Project coordinator

Prof. Dr. Mark W. Greenlee

Project members at University of Regensburg

Dr. Gyula Kovács, Markus Raabe

Funding period

2006 - 2009

Objectives

"Decisions in Motion" is a EU Commission project funded in the platform FP6 IST Cognitive Systems.

The goal is to model and implement fast sensory-based decision making in moving cognitive agents. A total of 8 European laboratories and 2 SMEs are collaborating on this project.

"BayernBrain3T", funded by Bayerische Forschungsstiftung

Project leaders

University Medical Center Regensburg, Department of Neurology, Prof. Dr. U. Bogdahn

University of Regensburg, Institute of Experimental Psychology, Prof. Dr. M. W. Greenlee

Project partners

Siemens AG

RAPID BioMedical GmbH

Funding period

2004 - 2007

Objectives

"BayernBrain3T" is a research and developmental project funded by Bayerische Forschungsstifung and dedicated to preclinical, neuropsychological and clinical research on a 3T high field MR scanner.

The goal of the project is to develop and optimise medical imaging techniques to evaluate diagnostic and therapeutic methods applied in the context of regeneration of CNS damage in particular and neuronal plasticity in general.

For more information see: http://www.forschungsstiftung.de/ (in German only)

DFG Priority Program "Executive Functions" (SPP 1107)

Subproject 12 "Neural correlates of executive functions in children with ADHD as measured by fMRI and MR-spectroscopy"

Project leader

Prof. Dr. Mark W. Greenlee

Project members

Petra Behlmer-Elster, Markus Raabe, Markus Mühlhan, Jale ?zyurt

Funding period

2003 - 2005

Objectives

Attention deficit hyperacitvity disorder (ADHD) is a phenotypically heterogeneous neuropsychiatric disorder that usually manifests itself in early childhood. The pathogenetic factors that lead to ADHD are only partly understood and remain a matter of considerable dispute. Accumulating evidence from on-going research indicates, however, that ADHD reflects a dysfunction of cortical and subcortical systems, and that these neuronal substrates form the basis of executive functions. The goal of the present research proposal is to investigate well diagnosed subgroups of pediatric ADHD patients with functional magnetic resonance imaging (fMRI) and magnet resonance spectroscopy (MRS). Using fMRI we intend to explore the neural correlates of fundamental subprocesses that contribute to executive functioning (such as response inhibition and working memory). Behavorial data recorded during the fMRI experiments can be used to validate possible differences in brain activation. The use of MRS should focus on possible pathologically altered neurochemical processes in ADHD. Using both technologies, we plan to investigate de novo patients clinically diagnosed with ADHD and compare these findings with those collected after treatment with methlyphenidate (MPH; the neuroactive substance e.g. in Ritalin). Such a comparison should reveal the effect of stimulants on the fMRI-BOLD responses to challenging tasks and to altered brain metabolism as revealed by MRS. ADHD-specific patterns of brain activation recorded during tasks that require executive function and/or alterations in neurochemical markers might help to better understand the neural basis of ADHD and might serve as biological markers to objectively validate the diagnosis of the disorder.

DFG funded International Graduate School?"Neurosensory Science and Systems: Measuring and Modelling the Processing of Sensory Information and its Applications" (GRK 591)

Workgroup Prof. Dr. Mark W. Greenlee "Functional magnetic resonance imaging in the human visual and oculomotor system"

Participating members

Prof. Dr. Mark W. Greenlee, Ignacio Vallines García (University of Regensburg), Riklef Weerda (University of Oldenburg)

For more information see: Progress reports 2002 and 2005