Download - Berlin School of Mind and Brain

Smadar Ovadia-Caro
Reduction of Inter-hemispheric Connectivity in Disorders of Consciousness
Disorders of consciousness (DOC) pose diagnostic challenges because patients can be
behaviorally unresponsive. A promising new approach towards DOC diagnosis may be
offered by the analysis of functional magnetic resonance imaging (fMRI) data acquired in
the absence of any task demands (“resting-state”). Previous work has shown reduced
functional connectivity within the "default network", a subset of regions known to be
deactivated during engaging tasks, which correlated with the degree of consciousness
impairment. However, it remains unclear whether the breakdown of connectivity is
restricted to the "default network", and to what degree changes in functional connectivity
can be observed at the single-subject level. Here, we analyzed resting-state interhemispheric
connectivity in three homotopic regions of interest, which could reliably be
identified based on distinct anatomical landmarks, and were part of an "externally
oriented network". Resting-state fMRI data were acquired for a group of 11 healthy
subjects and 8 DOC patients. At the group level, our results indicate decreased interhemispheric
functional connectivity in patients with impaired awareness as compared to
subjects with intact awareness. The single-case statistic by Crawford & Howell (1998)
indicated a significant deviation from the healthy sample in 5/8 patients. Importantly, of
the three patients whose connectivity indices were comparable to the healthy sample, one
was diagnosed as locked-in. Our results highlight the clinical potential of resting-state
fMRI data, and suggest further investigation of inter-hemispheric connectivity as a
complementary diagnostic measure for DOC patients.
Sophie Herbst
The Mystery of the Internal Clock, or What do we Know about Time
Perception?
Time perception is becoming a popular research field again, based on its long-standing
history that dates back to antique philosophers. In my talk I’ll give a short insight on the
topic from a psychological viewpoint, illustrated by recent discussions in the scientific
community and discuss how state-of-the-art neuroscience methods can help to uncover
the mysteries of which there are still plenty in this field.
Subsequently I will focus on my thesis’ question: how perceptual processes can influence
our internal time keeping mechanisms. Different views exist about whether subjective
duration is based on early perceptual processes or relates to higher-level stimulus
processing requiring attention. In order to distinguish between the influences of early and
late processes perceptual processing on perceived duration, we applied a well-established
paradigm from attention research: the Attentional Blink. Our preliminary findings argue
for a specific influence of higher-level cognitive processes on perceived duration, or – in
other words – suggest that simple changes in visual input do not fully explain the
emergence of subjective duration.
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