The FN400 is functionally distinct from the N400

The FN400 refers to the early midfrontally-distributed difference between ERPs elicited by old and new items, which operates in a way consistent with a neural marker of familiarity-based recognition. Double dissociations between the FN400 and a later ERP index of recollection provide some of the most compelling evidence in support of dual-process models to date. It has recently been claimed, however, that there is no evidence that the FN400 is functionally distinct from the N400 index of implicit semantic priming (Voss, J., and Federmeier, K., FN400 potentials are functionally identical to N400 potentials and reflect semantic processing during recognition testing, Psychophysiology, 48, 532-546, 2011), challenging inferences made on the basis of this effect. We argue that the design employed to make this claim is flawed because it comprised a semantic priming manipulation embedded within a continuous recognition test which enabled recognition contrasts to be confounded by semantic processes in a number of ways. Here, ERPs were recorded from a design which avoided these confounds by employing a semantic priming paradigm which also served as the encoding phase for a surprise subsequent recognition test phase. An N400 effect elicited in the semantic priming task demonstrated the established centro-parietal maximum, whereas the difference between correctly responded to old and new ERPs in the recognition test was maximal over frontal sites in the same time window. When direct comparisons of the electrophysiological correlates of semantic priming and episodic recognition are recorded in a paradigm in which the two are not confounded, the FN400 reflects a qualitatively distinct effect from the N400.     

The faces of Moebius syndrome: recognition and anticipatory guidance

Moebius syndrome is a rare congenital disorder characterized mainly by the inability to move the eyes laterally or produce facial expressions such as smiling. Moebius syndrome creates physical problems for the affected individual that may, in some cases, lead to emotional or social adjustment issues, yet the syndrome is relatively unknown among healthcare professionals. Because early recognition of Moebius syndrome can lead to early diagnosis and treatment, education of nurses in perinatal, pediatric, midwifery, and neonatal specialties is crucial. Through early recognition, maternal-child nurses can offer anticipatory guidance and provide or recommend resources to parents of children with this neurological condition.     

The hippocampal region is involved in successful recognition of both remote and recent famous faces

There is currently a debate regarding the precise role of medial temporal regions in memory, in particular regarding the time scale of their involvement in conscious recollection of information stored in long-term memory. Using event-related fMRI, we have attempted to contribute to this debate by identifying brain regions associated with the successful recognition of famous faces from two different periods: "Old" faces of people who became famous in the 1960s-1970s and "Recent" faces of people who became famous in the 1990s. We demonstrate that the hippocampus is involved in the successful recognition of famous faces from both periods and does not appear to distinguish between these two periods. We also highlight a network of brain regions, including the left prefrontal cortex, the retrosplenial cortex, the temporo-parietal junction, the caudate and the right cerebellum, which is activated in association with successful recognition of famous faces. Finally, an analysis of the results obtained during a post hoc episodic recognition task shows the specific involvement of anterior hippocampus in the successful encoding of the unfamiliar faces, which were presented during the fame decision task, suggesting a functional distinction between anterior and posterior parts of the hippocampus, the former being specifically involved in successful episodic encoding and the latter being associated with successful retrieval of semantic information.     

Distinct neural systems for the encoding and recognition of topography and faces

In a series of three positron emission tomography experiments the functional neuroanatomy of four different types of visual stimuli was investigated within the same experimental context. The stimuli were unknown buildings, landscapes, human faces, and animal faces. The purpose of the present study was to compare the stimulus types, both within the same category and across category, by examining if, at encoding (with several seconds exposure to each stimulus) or recognition (over time scales of minutes compared to the seconds of usual perception/one-back studies), common or different neural circuits were activated for all types/categories of stimuli. Within category and although visually very different, the encoding of both buildings and landscapes activated a similar set of brain regions, including bilateral parahippocampal gyrus. This was in contrast to the encoding of both human and animal faces, both of which resulted in activation of the fusiform gyrus bilaterally. Despite the perceptual inputs being identical to those during encoding, the recognition of both buildings and landscapes activated only unilateral right parahippocampal gyrus, while recognition of both human and animal faces activated unilateral right fusiform gyrus. In addition, right superior frontal gyrus and right inferior and medial parietal areas were more active during recognition compared with encoding for all stimulus types. Overall the data identify differential patterns of activation for encoding compared with retrieval of visual stimuli. Furthermore, medial temporal structures specifically are involved in the explicit learning and long-term recognition of topographically relevant stimuli, be they buildings or landscapes, while lateral temporal structures support nontopographical learning and recognition, in this case either human or animal faces.     

Electrophysiological neural mechanisms for detection, configural analysis and recognition of faces

Despite ample explorations the nature of neural mechanisms underlying human expertise in face perception is still undetermined. Here we examined the response of two electrophysiological signals, the N170 ERP and induced gamma-band activity (>20 Hz), to face orientation and familiarity across two blocks, one in which the face identity was task-relevant and one in which it was not. N170 amplitude to inverted faces was higher than to upright faces and was not influenced by face familiarity or its task relevancy. In contrast, induced gamma activity was higher for upright than for inverted faces and for familiar than unfamiliar faces. The effect of face inversion was found in lower gamma frequency band (25-50 Hz), whereas familiarity affected amplitudes in higher gamma frequency band (50-70 Hz). For gamma, the relevance of face identity to the task modulated both inversion and familiarity effects. These findings pinpoint three functionally dissociated neural mechanisms involved in face processing, namely, detection, configural analysis, and recognition.     

The changing faces of diabetes

As understanding about the pathophysiology of diabetes mellitus continues to evolve, it is important that its classification reflects the current state of knowledge. The eventual goal is that appreciation of the different forms of diabetes eventually will result in better treatment of hyperglycemia. Even more exciting is the fact that this appreciation is allowing us to enter the era of diabetes prediction and prevention. The current classification scheme of diabetes does not yet account for all of the types of diabetes seen in a typical diabetes clinic. Fig. 1 illustrates our current understanding of the pathophysiology of diabetes and separates the diabetes types into those used in the current classification scheme. Clearly, new classifications will be required as we learn more about the different types of diabetes.