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Recurrent Neural Processing in Somatosensory Awareness
The characteristics of neural processing underlying conscious stimulus detection, despite
extensive research, remain elusive. As a prominent theoretical account of visual
awareness, the recurrent processing hypothesis states that while stimuli generally evoke
feedforward activity propagating through the visual cortex, stimuli which become
consciously detected are further processed in feedforward-feedback loops established
between various stages of visual processing.
Although this hypothesis has not been tested directly in modalities other than vision,
monkey studies have provided indirect evidence for feedback processing in somatosensory
detection. Here we applied dynamic causal modelling (DCM) to EEG data acquired from
humans in a somatosensory detection task to test this theory. In the analysis, we focused
on model-based evidence for feedforward, feedback and recurrent processing between
primary and secondary somatosensory cortices. Our results suggest that increased
recurrent processing within the somatosensory system, dominated by an enhanced cSIcSII
connection, underlies somatosensory awareness.
Saskia Köhler
The Role of the Brain in Impulsivity and Self-Control
Impulsivity is a personality trait that is present in healthy individuals. However, high
impulsivity may also cause problems in social life, such as troubles in partnership, fights,
and traffic violations. This is because impulsive actions are often rapid, unplanned, hasty
and without regard to negative consequences. The opposite of impulsivity can be
described as self-control, given that people showing high impulsivity have problems
controlling their actions, thoughts and emotions. Since an association between impulsivity
and mental illness is apparent, neuroscientific research in this field is important. In my
PhD project, I investigate the role of the brain in impulsivity and self-control with
different approaches: (1) administering different functional magnetic resonance imaging
(fMRI) paradigms, which provoke impulsive or self-controlled behavior, (2) examining
fMRI resting state measurements, (3) examining MRI structural measurements, and (4)
determining the influence of virtual lesions with transcranial direct current stimulation
(tDCS). I examine psychiatric patients, which are characterized by high impulsivity and
low self-control competencies (alcohol dependent patients and pathological gamblers),
and healthy subjects. I will present results from at least one of these approaches.
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