The role of the IPL in person identification.

We investigate the brain activations when identifying a newly encountered individual as being the same as a person previously perceived, a fundamental but seldom acknowledged process. In an identity condition, two faces had to be identified as the same person in contrast to a control condition, in which two faces had to be recognised as belonging to similar looking twins. Our results demonstrate an increase of neural activation in frontal as well as in parietal areas including the left inferior parietal lobe and the precuneus during identification. We introduce mental files theory to model this process as a linking of co-referential files and identify important connections to other domains in neurological and cognitive science (e.g., delusional misidentification syndromes, theory of mind).

Left ventral occipitotemporal activation during orthographic and semantic processing of auditory words.

The present fMRI study investigated the hypothesis that activation of the left ventral occipitotemporal cortex (vOT) in response to auditory words can be attributed to lexical orthographic rather than lexico-semantic processing. To this end, we presented auditory words in both an orthographic ("three or four letter word?") and a semantic ("living or nonliving?") task. In addition, a auditory control condition presented tones in a pitch evaluation task. The results showed that the left vOT exhibited higher activation for orthographic relative to semantic processing of auditory words with a peak in the posterior part of vOT. Comparisons to the auditory control condition revealed that orthographic processing of auditory words elicited activation in a large vOT cluster. In contrast, activation for semantic processing was only weak and restricted to the middle part vOT. We interpret our findings as speaking for orthographic processing in left vOT. In particular, we suggest that activation in left middle vOT can be attributed to accessing orthographic whole-word representations. While activation of such representations was experimentally ascertained in the orthographic task, it might have also occurred automatically in the semantic task. Activation in the more posterior vOT region, on the other hand, may reflect the generation of explicit images of word-specific letter sequences required by the orthographic but not the semantic task. In addition, based on cross-modal suppression, the finding of marked deactivations in response to the auditory tones is taken to reflect the visual nature of representations and processes in left vOT.

Altered network properties of the fronto-parietal network and the thalamus in impaired consciousness.

Recovery of consciousness has been associated with connectivity in the frontal cortex and parietal regions modulated by the thalamus. To examine this model and to relate alterations to deficits in cognitive functioning and conscious processing, we investigated topological network properties in patients with chronic disorders of consciousness recovered from coma. Resting state fMRI data of 34 patients with unresponsive wakefulness syndrome and 25 in minimally conscious state were compared to 28 healthy controls. We investigated global and local network characteristics. Additionally, behavioral measures were correlated with the local metrics of 28 regions within the fronto-parietal network and the thalamus. In chronic disorders of consciousness, modularity at the global level was reduced suggesting a disturbance in the optimal balance between segregation and integration. Moreover, network properties were altered in several regions which are associated with conscious processing (particularly, in medial parietal, and frontal regions, as well as in the thalamus). Between minimally conscious and unconscious patients the local efficiency of medial parietal regions differed. Alterations in the thalamus were particularly evident in non-conscious patients. Most of the regions affected in patients with impaired consciousness belong to the so-called 'rich club' of highly interconnected central nodes. Disturbances in their topological characteristics have severe impact on information integration and are reflected in deficits in cognitive functioning probably leading to a total breakdown of consciousness.

Common brain areas engaged in false belief reasoning and visual perspective taking: a meta-analysis of functional brain imaging studies.

We performed a quantitative meta-analysis of functional neuroimaging studies to identify brain areas which are commonly engaged in social and visuo-spatial perspective taking. Specifically, we compared brain activation for visual-perspective taking to activation for false belief reasoning, which requires awareness of perspective to understand someone's mistaken belief about the world which contrasts with reality. In support of a previous account by Perner and Leekam (2008), our meta-analytic conjunction analysis found common activation for false belief reasoning and visual perspective taking in the left but not the right dorsal temporo-parietal junction (TPJ). This fits with the idea that the left dorsal TPJ is responsible for representing different perspectives in a domain-general fashion. Moreover, our conjunction analysis found activation in the precuneus and the left middle occipital gyrus close to the putative Extrastriate Body Area (EBA). The precuneus is linked to mental-imagery which may aid in the construction of a different perspective. The EBA may be engaged due to imagined body-transformations when another's viewpoint is adopted.

Processing counterfactual and hypothetical conditionals: an fMRI investigation.

Counterfactual thinking is ubiquitous in everyday life and an important aspect of cognition and emotion. Although counterfactual thought has been argued to differ from processing factual or hypothetical information, imaging data which elucidate these differences on a neural level are still scarce. We investigated the neural correlates of processing counterfactual sentences under visual and aural presentation. We compared conditionals in subjunctive mood which explicitly contradicted previously presented facts (i.e. counterfactuals) to conditionals framed in indicative mood which did not contradict factual world knowledge and thus conveyed a hypothetical supposition. Our results show activation in right occipital cortex (cuneus) and right basal ganglia (caudate nucleus) during counterfactual sentence processing. Importantly the occipital activation is not only present under visual presentation but also with purely auditory stimulus presentation, precluding a visual processing artifact. Thus our results can be interpreted as reflecting the fact that counterfactual conditionals pragmatically imply the relevance of keeping in mind both factual and supposed information whereas the hypothetical conditionals imply that real world information is irrelevant for processing the conditional and can be omitted. The need to sustain representations of factual and suppositional events during counterfactual sentence processing requires increased mental imagery and integration efforts. Our findings are compatible with predictions based on mental model theory.