My research focusses on different aspects of cognitive control, attention, and working memory. I mainly use fMRI and have a particular interest in the inferior frontal junction area (IFJ). The IFJ is a great little brain area in the posterior prefrontal cortex that has been shown to be involved in all of the cognitive functions mentioned above. Actually, as shown in a massive meta-analysis by Tal Yarkoni and colleagues, it is one of the most frequently activated areas in fMRI studies in general.
The term 'inferior frontal junction' was coined by Yves von Cramon. It refers to the IFJ's location at the junction of the inferior frontal sulcus and the inferior precentral sulcus. A number of fMRI studies conducted at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig in the late 1990's and early 2000's had very consistently found activations at the junction of these two sulci, sparking the creation of the term IFJ. Interestingly, however, none of the classic cyto-architectonic maps includes a brain area corresponding to the IFJ in location and extent. So, is the IFJ really an area? Recent research suggests that it is. Katrin Amunts and her group at the Research Center Jülich found evidence for the existence of a previously uncharted area at the junction of the inferior frontal sulcus and the inferior precentral sulcus. This is likely one of the very rare cases where fMRI data have facilitated the discovery of a cyto-architectonic area!
Based on task switching and Stroop studies, we initially described the function of the IFJ as 'updating of task representations'. While I still believe that the IFJ is involved in updating processes, over the years it has become clear that this characterisation describes only one aspect of the functionality of the IFJ. My current hypothesis is that the IFJ represents abstract task-relevant properties of objects. These abstract properties can be task rules (as proposed by our original hypothesis), but can also be other conceptual representations associated with objects. I also assume that these properties depend on the task context (in the sense of John Duncan's adaptive coding model). There is now good evidence, mainly based on work by René Marois' group, that the processing capacity of the IFJ is somewhat limited and that it therefore represents an information processing bottleneck. In addition, as previously hypothesised by us, there is now also evidence that the IFJ is involved in the top-down control of lower-level brain areas (as, for example, shown by Adam Gazzaley's and Robert Desimone's groups).
In future projects, I intend to utilise ultra-high field fMRI to further investigate the functional organisation of the IFJ and its interactions with other brain areas. Furthermore, I plan to use transcranial direct current stimulation, a method that, contrary to fMRI, allows causal inferences about the functional role of brain regions.
I am also interested in neuroanatomy in general and in the history of neuroscience. I particularly esteem Sigmund Exner's prescient "Entwurf zu einer physiologischen Erklärung der psychischen Erscheinungen" [Project for a physiological explanation of mental phenomena], which unfortunately was never translated into English (if I ever have the feeling that I have too much spare time, I might attempt a translation...).
For those also interested in the history of neuroscience: I have PDFs of some classic, mostly German works (now in the public domain) which I would be happy to share if contacted by e-mail. Among them are:
- Brodmann (1909), Vergleichende Lokalisationslehre der Grosshirnrinde in ihren Prinzipien dargestellt auf Grund des Zellenbaues
- Cunningham (1892), Contribution to the surface anatomy of the cerebral hemispheres
- Eberstaller (1890), Das Stirnhirn. Ein Beitrag zur Anatomie der Oberfläche des Grosshirns
- Ecker (1869), Die Hirnwindungen des Menschen nach eigenen Untersuchungen insbesondere über die Entwicklung derselben beim Fötus und mit Rücksicht auf das Bedürfnis der Ärzte [what a title!]
- Retzius (1896), Das Menschenhirn