Research:
Brain Machine Interfacing:
In a collaboration with Fraunhofer
in Magdeburg, the Knight Lab at UC Berkeley and UC San Francisco we
recently started a project on Brain Machine Interfacing (BMI). Our
goals are to use non-invasive and invasive brain activation to control
robotic devices, and for cognitive BMIs. We have recently organized the interdisciplinary 1st Magdeburg Workshop an Brain Machine Interfacing.
Publications
on BMI
Collaborators: Hermann Hinrichs, Robert T. Knight, Ulrich Schmucker, Edward Chang
Acquisition of information from
natural scenes:
The human visual system
acquires information from cluttered natural
scenes much faster and more efficient than one might expected from
experiments using relatively simple stimuli (dots,
gratings etc.). Only 40 ms cortical processing of a
photography of a
natural scene are sufficient to discriminate scenes according to their
semantic content, for semantic object contetxt interactions to develop
and to obtain enough information to rember the seen as previously
seen. We
investigate the dynamics of
the
information acquisition from natural scenes and the interactions
between object and context at several cognitive and perceptual levels.
In our investigations we
combine fMRI, MEG, EEG, psychophysics, and single trial classification
approaches to analyze the sequence of the brain processes involved in
information extraction and recognition, the role of prior knowledge
about the structure of the natural world, and to test the predictivity
of brain processes for the subjective percept on a trial-by-trial basis.
Publications
on natural scenes
Collaborators:
Karl Gegenfurtner,
Rudolf Kruse, H.H. Bülthoff
Constructive perception
and eye movements:
We perceive objects in
our
environment as integrated wholes, even when they are covered
by
other objects, and thus only some fragments of the object are
simulatneously visible. These subjective object percepts are of high
ecological importance as they allows us to recognize and react to
obects even when they are only partly visible (e.g. a predator sneaking
behind trees). How the visual system constructs the subjective object
percepts is still a mystery. Suggestions range from the highly
cognitive "knowing what it is hypothesis" to the sensory, so-called
"retinal painting hypothesis" which was put forward for example by
Helmholtz some 150 years ago.
The
latter assumes that the eyes follow the occluded "object" and thereby
paint successively visible object parts onto adjacent parts of the
retina. Our
investigations
show that under natural free viewing conditions the retinal painting
hypothsis can be rejected because retinal painting by smooth pursuit
eye movements is neither necessary nor sufficient to explain the figure
percept. We currently investigate the brain networks that construct the
object percepts and how the brain switches between the percept of the
physical stimulus and the subjective object percept.
Publications
on constructive object perception and eye movements.
Collaborator: Robert
Fendrich
Voluntary eye
movements:
Humans scan the visual
environment
with a rapid sequence of voluntary saccadic eye movements that move the
center of regard between differnt point of interest in a
scene.
Despite the shifts of the retinal image we do not perceive the world as
moving between saccades. This is, however, the case when the retinal
images are presented as a movies. Our aim in this project was to
investigate the effects of voluntary eye movements in the visual system
and how the brain constructs the stable percept of the world.
Publications
on constructive object perception and eye movements.
Collaborator:
Ivan Bodis-Wollner
Color
and motion processing:
According
to the classic view the
brain processes visual information in a fast color insensitive and in a
slow color sensitive channel.
We
investigate via parametric
designs using fMRI the temporal and chromatic sensitivity of visual
ares in the brain with simple and complex stimuli. We implemented
retinotopic mapping and other functional localizers to perform detailed
measurements in independently localized visual areas.
Publications
on color coding
Collaborators:
Karl Gegenfurtner,
Brian Wandell
Consciousness and the
freedom of will
I'm interested in
interdisciplinary,
epistemological, and ethical aspects of the discussion about
consciousness and freedom of will. Together with colleagues from
Philosophy and Psychology we organized in 2002 an interdisciplinary
workshop on the topic. The results are published as a book
(sorry
in German only).
Publications
on consciousness
Collaborators:
Christoph Herrman, Silke Schicktanz, and Michael Pauen
Migraine:
We
collaborated with Markus Dahlem
who has developed a physiologically and physically motivated model for
the migraine aura. See his webpage for more detailed
information.
Collaborators:
Markus Dahlem
Methods:
Psychophysics
fMRI: Various standard and
non-standard techniques (GLM, functional ROI definition incl.
retinotopic mapping,...),
simultaneous recording of EEG
and fMRI. Information about
the MR-facilities available in Magdeburg can be found here.
MEG and EEG
Eye
movements: dual
purkinje
tracker and video based, custom build systems (thanks to Martin
Kanowski :-).
Analysis techniques:
Wavelet
analysis, single
trial classification, ...
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Modified 08/09/10
