Person identity-specific adaptation effects in the ventral occipito-temporal cortex

Identifying the faces of familiar persons requires the ability to assign several different images of a face to a common identity. Previous research showed that the occipito-temporal cortex, including the fusiform and the occipital face areas, is sensitive to personal identity. Still, the viewpoint, facial expression, and image-independence of this information are currently under heavy debate. Here we adapted a rapid serial visual stimulation paradigm (Johnston et al., 2016) and presented highly variable ambient-face images of famous persons to measure fMRI adaptation. FMRI adaptation is considered as the neuroimaging manifestation of repetition suppression, a neural phenomenon currently explained as a correlate of reduced predictive error responses for expected stimuli. We revisited the question of image-invariant identity-specific encoding mechanisms of the occipito-temporal cortex, using fMRI adaptation with a particular interest in predictive mechanisms. Participants were presented with trials containing eight different images of a famous person, images of eight different famous persons, or seven different images of a particular famous person followed by an identity change to violate potential expectation effects about person identity. We found an image-independent adaptation effect of identity for famous faces in the fusiform face area. However, in contrast to previous electrophysiological studies, using similar paradigms, no release of the adaptation effect was observed when identity-specific expectations were violated. Our results support recent multivariate pattern analysis studies, showing image-independent identity encoding in the core face-processing areas of the occipito-temporal cortex. These results are discussed in the frame of recent identity-processing models and predictive mechanisms

Identification of a Small Molecule Inhibitor of Importin β Mediated Nuclear Import by Confocal On-Bead Screening of Tagged One-Bead One-Compound Libraries

In eukaryotic cells, proteins and RNAs are transported between the nucleus and the cytoplasm by nuclear import and export receptors. Over the past decade, small molecules that inhibit the nuclear export receptor CRM1 have been identified, most notably,leptomycin B. However, up to now no small molecule inhibitors of nuclear import have been described. Here we have used our automated confocal nanoscanning and bead picking method (CONA) for on-bead screening of a one-bead one-compound library to identify the first such import inhibitor, karyostatin 1A. Karyostatin 1A binds importin beta with high nanomolar affinity and specifically inhibits importin alpha/beta mediated nuclear import at low micromolar concentrations in vitro and in living cells, without perturbing transportin mediated nuclear import or CRM1 mediated nuclear export. Surface plasmon resonance binding-experiments suggest that karyostatin 1A acts by disrupting the interaction between importin p and the OPase Ran. As a selective inhibitor of the importin alpha/beta import pathway, karyostatin 1A will provide a valuable tool for future studies of nucleocytoplasmic trafficking.</p

Right hemisphere advantage in statistical learning: evidence from a probabilistic sequence learning task

Picking up statistical regularities of patterns from the environment is essential for predictive and adaptive behavior. One of the most important challenges is to understand how statistical learning occurs and how the acquired information consolidates and stabilizes in the brain. Evidence suggests that the prefrontal cortex (PFC) has a critical role in these processes; the division of labor between hemispheres, however, is less characterized. The aim of the present study was to directly investigate the causal role of the right and left PFC in statistical learning and its consolidation. Healthy, young adults were trained on a probabilistic sequence learning task. Anodal transcranial direct current stimulation (tDCS) over the right or left dorsolateral PFC (DLPFC) was applied during the training in order to modify learning-related cortical plasticity in the targeted brain regions by increasing neural excitability. Performance was tested during and immediately after the stimulation, 2-hour and 24-hour later. We found that the anodal tDCS over the right DLPFC led to enhanced learning performance both after the 2-hour and 24-hour retention periods, suggesting the causal role of this area in statistical learning. In contrast, we did not find any effect of left DLPFC stimulation on learning. These results highlight the role of the right fronto-striatal network in statistical learning and its consolidation

Evidence for a General Neural Signature of Face Familiarity

We explored the neural signatures of face familiarity using cross-participant and cross-experiment decoding of event-related potentials, evoked by unknown and experimentally familiarized faces from a set of experiments with different participants, stimuli, and familiarization-types. Human participants of both sexes were either familiarized perceptually, via media exposure, or by personal interaction. We observed significant cross-experiment familiarity decoding involving all three experiments, predominantly over posterior and central regions of the right hemisphere in the 270–630 ms time window. This shared face familiarity effect was most prominent across the Media and the Personal, as well as between the Perceptual and Personal experiments. Cross-experiment decodability makes this signal a strong candidate for a general neural indicator of face familiarity, independent of familiarization methods, participants, and stimuli. Furthermore, the sustained pattern of temporal generalization suggests that it reflects a single automatic processing cascade that is maintained over time

Characterizing the shared signals of face familiarity: long-term acquaintance, voluntary control, and concealed knowledge

In a recent study using cross-experiment multivariate classification of EEG patterns, we found evidence for a shared familiarity signal for faces, patterns of neural activity that successfully separate trials for familiar and unfamiliar faces across participants and modes of familiarization. Here, our aim was to expand upon this research to further characterize the spatio-temporal properties of this signal. By utilizing the information content present for incidental exposure to personally familiar and unfamiliar faces, we tested how the information content in the neural signal unfolds over time under different task demands – giving truthful or deceptive responses to photographs of genuinely familiar and unfamiliar individuals. For this goal, we re-analyzed data from two previously published experiments using within-experiment leave-one-subject-out and cross-experiment classification of face familiarity. We observed that the general face familiarity signal, consistent with its previously described spatio-temporal properties, is present for long-term personally familiar faces under passive viewing, as well as for acknowledged and concealed familiarity responses. Also, central-posterior regions contain information related to deception. We propose that signals in the 200–400 ms window are modulated by top-down task-related anticipation, while the patterns in the 400–600 ms window are influenced by conscious effort to deceive. To our knowledge, this is the first report describing the representational dynamics of concealed knowledge for faces, using time-resolved multivariate classification

Cautious or causal? Key implicit sequence learning paradigms should not be overlooked when assessing the role of DLPFC (Commentary on Prutean et al.)

The role of the dorsolateral prefrontal cortex (DLPFC) in implicit sequence/statistical learning has received considerable attention in recent cognitive neuroscience research. Studies have used non-invasive brain stimulation methods to test whether the DLPFC plays a role in the incidental acquisition and expression of implicit sequence learning. In a recent study, Prutean et al. has concluded that stimulating the left or the right DLPFC might not affect the expression of implicit sequence learning measured by the Serial Reaction Time (SRT) task. The authors speculated that the previous results revealing improved implicit sequence learning following DLPFC stimulation might have been found because explicit awareness accumulated with the use of Alternating Serial Reaction Time (ASRT) task. Our response presents solid evidence that the ASRT task measures implicit sequence learning that remains unconscious both at the judgment and structural level. Therefore, contrary to the conclusion of Prutean et al., we argue that the DLPFC could have a crucial effect on implicit sequence learning that may be task-dependent. We suggest that future research should focus on the specific cognitive processes that may be differentially involved in the SRT versus ASRT tasks, and test what the role of the DLPFC is in those specific cognitive processes

Getting to Know You: Emerging Neural Representations during Face Familiarization.

The successful recognition of familiar persons is critical for social interactions. Despite extensive research on the neural representations of familiar faces, we know little about how such representations unfold as someone becomes familiar. In three EEG experiments on human participants of both sexes, we elucidated how representations of face familiarity and identity emerge from different qualities of familiarization: brief perceptual exposure (Experiment 1), extensive media familiarization (Experiment 2), and real-life personal familiarization (Experiment 3). Time-resolved representational similarity analysis revealed that familiarization quality has a profound impact on representations of face familiarity: they were strongly visible after personal familiarization, weaker after media familiarization, and absent after perceptual familiarization. Across all experiments, we found no enhancement of face identity representation, suggesting that familiarity and identity representations emerge independently during face familiarization. Our results emphasize the importance of extensive, real-life familiarization for the emergence of robust face familiarity representations, constraining models of face perception and recognition memory.SIGNIFICANCE STATEMENT Despite extensive research on the neural representations of familiar faces, we know little about how such representations unfold as someone becomes familiar. To elucidate how face representations change as we get familiar with someone, we conducted three EEG experiments where we used brief perceptual exposure, extensive media familiarization, or real-life personal familiarization. Using multivariate representational similarity analysis, we demonstrate that the method of familiarization has a profound impact on face representations, and emphasize the importance of real-life familiarization. Additionally, familiarization shapes representations of face familiarity and identity differently: as we get to know someone, familiarity signals seem to appear before the formation of identity representations

The occipital face area is causally involved in identity‑related visual‑semantic associations

Faces are processed in a network of areas within regions of the ventral visual stream. However, familiar faces typically are characterized by additional associated information, such as episodic memories or semantic biographical information as well. The acquisition of such non-sensory, identity-specific knowledge plays a crucial role in our ability to recognize and identify someone we know. The occipital face area (OFA), an early part of the core face-processing network, is recently found to be involved in the formation of identity-specific memory traces but it is currently unclear if this role is limited to unimodal visual information. The current experiments used transcranial magnetic stimulation (TMS) to test whether the OFA is involved in the association of a face with identity-specific semantic information, such as the name or job title of a person. We applied an identity-learning task where unfamiliar faces were presented together with a name and a job title in the first encoding phase. Simultaneously, TMS pulses were applied either to the left or right OFA or to Cz, as a control. In the subsequent retrieval phase, the previously seen faces were presented either with two names or with two job titles and the task of the participants was to select the semantic information previously learned. We found that the stimulation of the right or left OFA reduced subsequent retrieval performance for the face-associated job titles. This suggests a causal role of the OFA in the association of faces and related semantic information. Furthermore, in contrast to prior findings, we did not observe hemispherical differences of the TMS intervention, suggesting a similar role of the left and right OFAs in the formation of the visual-semantic associations. Our results suggest the necessity to reconsider the hierarchical face-perception models and support the distributed and recurrent models

Effects of motor restrictions on preparatory brain activity.

Modifying established motor skills is a challenging endeavor due to proactive interference from undesired old to desired new actions, calling for high levels of cognitive control. Motor restrictions may facilitate the modification of motor skills by rendering undesired responses physically impossible, thus reducing demands to response inhibition. Here we studied behavioral and EEG effects of rule changes to typing in skilled touch-typists. The respective rule change-typing without using the left index finger-was either implemented per instruction only or with an additional motor restriction. In both groups, the rule change elicited delays and more errors in typing, indicating the occurrence of proactive interference. While stimulus-locked ERPs did not exhibit prominent effects of rule change or group, response-locked ERPs revealed that the time courses of preparatory brain activity preceding typing responses depended on the presence of motor restriction. Although further research is necessary to corroborate our findings, they indicate a novel brain correlate that represents changes in inhibitory response preparation induced by short-term motor restrictions