Shared neural codes of recognition memory

Recognition memory research has identified several electrophysiological indicators of successful memory retrieval, known as old-new effects. These effects have been observed in different sensory domains using various stimulus types, but little attention has been given to their similarity or distinctiveness and the underlying processes they may share. Here, a data-driven approach was taken to investigate the temporal evolution of shared information content between different memory conditions using openly available EEG data from healthy human participants of both sexes, taken from six experiments. A test dataset involving personally highly familiar and unfamiliar faces was used. The results show that neural signals of recognition memory for face stimuli were highly generalized starting from around 200 ms following stimulus onset. When training was performed on non-face datasets, an early (around 200–300 ms) to late (post-400 ms) differentiation was observed over most regions of interest. Successful cross-classification for non-face stimuli (music and object/scene associations) was most pronounced in late period. Additionally, a striking dissociation was observed between familiar and remembered objects, with shared signals present only in the late window for correctly remembered objects, while cross-classification for familiar objects was successful in the early period as well. These findings suggest that late neural signals of memory retrieval generalize across sensory modalities and stimulus types, and the dissociation between familiar and remembered objects may provide insight into the underlying processes

Causal evidence of the involvement of the right occipital face area in face-identity acquisition

There is growing evidence that the occipital face area (OFA), originally thought to be involved in the construction of a low-level representation of the physical features of a face, is also taking part in higher-level face processing. To test whether the OFA is causally involved in the learning of novel face identities, we have used transcranial magnetic stimulation (TMS) together with a sequential sorting – face matching paradigm (Andrews et al. 2015). First, participants sorted images of two unknown persons during the initial learning phase while either their right OFA or the Vertex was stimulated using TMS. In the subsequent test phase, we measured the participants’ face matching performance for novel images of the previously trained identities and for two novel identities. We found that face-matching performance accuracy was higher for the trained as compared to the novel identities in the vertex control group, suggesting that the sorting task led to incidental learning of the identities involved. However, no such difference was observed between trained and novel identities in the rOFA stimulation group. Our results support the hypothesis that the role of the rOFA is not limited to the processing of low-level physical features, but it has a significant causal role in face identity encoding and in the formation of identity-specific memory-traces

No semantic information is necessary to evoke general neural signatures of face familiarity: evidence from cross-experiment classification

Recent theories on the neural correlates of face identification stressed the importance of the available identity-specific semantic and affective information. However, whether such information is essential for the emergence of neural signal of familiarity has not yet been studied in detail. Here, we explored the shared representation of face familiarity between perceptually and personally familiarized identities. We applied a cross-experiment multivariate pattern classification analysis (MVPA), to test if EEG patterns for passive viewing of personally familiar and unfamiliar faces are useful in decoding familiarity in a matching task where familiarity was attained thorough a short perceptual task. Importantly, no additional semantic, contextual, or affective information was provided for the familiarized identities during perceptual familiarization. Although the two datasets originate from different sets of participants who were engaged in two different tasks, familiarity was still decodable in the sorted, same identity matching trials. This finding indicates that the visual processing of the faces of personally familiar and purely perceptually familiarized identities involve similar mechanisms, leading to cross-classifiable neural patterns

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

Az implicit tanulás és a nyelvi képességek kapcsolata

A tanulmány az implicit tanulás és a mondatmegértés kapcsolatát vizsgálja kettős terheléses kísérleti helyzetben. A kísérleti személyeknek az implicit tanulási feladattal - szeriális reakcióidő (SRT) — párhuzamosan mondatmegértési, szófeldolgozási, és matematikai feladatokat kellett végrehajtaniuk. Az implicit tanulási teljesítmény a mondatmegértési feladat közben szignifikánsan rosszabb volt, mint a kontroll helyzetekben. Az eredmények összhangban vannak PINKER és ULLMAN procedurális/deklaratív elméletével. The main purpose of this research is to study the relationship between implicit learning and sentence processing. The authors present a dual-task experiment, in witch the subject's implicit learning was measured by a serial reaction time (SRT) task, and at the same time subjects were tested on sentence processing, word processing, and mathematical tasks. Results show that implicit learning is significantly worse when the parallel task was sentence processing than when it was either nonword-detection or counting. These findings are interpreted in the framework of Pinker and Ullman's procedural/declarative

The neural dynamics of familiarity-dependent face identity representation

Recognizing a face as belonging to a given identity is essential in our everyday life. Clearly, the correct identification of a face is only possible for familiar people, but ‘familiarity’ covers a wide range—from people we see every day to those we barely know. Although several studies have shown that the processing of familiar and unfamiliar faces is substantially different, little is known about how the degree of familiarity affects the neural dynamics of face identity processing. Here, we report the results of a multivariate EEG analysis, examining the representational dynamics of face identity across several familiarity levels. Participants viewed highly variable face images of 20 identities, including the participants' own face, personally familiar (PF), celebrity and unfamiliar faces. Linear discriminant classifiers were trained and tested on EEG patterns to discriminate pairs of identities of the same familiarity level. Time-resolved classification revealed that the neural representations of identity discrimination emerge around 100ms post-stimulus onset, relatively independently of familiarity level. In contrast, identity decoding between 200 and 400ms is determined to a large extent by familiarity: it can be recovered with higher accuracy and for a longer duration in the case of more familiar faces. In addition, we found no increased discriminability for faces of PF persons compared to those of highly familiar celebrities. One's own face benefits from processing advantages only in a relatively late time-window. Our findings provide new insights into how the brain represents face identity with various degrees of familiarity and show that the degree of familiarity modulates the available identity-specific information at a relatively early time window

Transkranielle Stromstimulation mit geringen Intensitäten: Die Effekte auf Kategorisierungsleistung und methodische Aspekte

Transkranielle Stromstimulation mit geringen Intensitäten (tES) bietet nicht nur die Möglichkeit der klinischen Intervention bei neurologischen Erkrankungen, sondern ist auch ein leistungsfähiges Forschungswerkzeug, um die Funktionsweise des gesunden menschlichen Gehirns besser verstehen zu können. Die erste Studie, die in der Arbeit dargestellt ist, zeigt, dass eine tES des dorsolateralen prefrontalen Kortex die Kategorisierungsleistung in der „A, not A“ Version des Prototypendistorsionstest beeinflussen kann. Diese Ergebnisse zeigen ein Verschwinden des Prototypeneffekts, wenn dieses Hirnareal mit anodaler transkranieller Gleichstromstimulation (tDCS) und transkranieller Zufallsrauschstimulation (tRNS) stimuliert wird. Di

3. Vorlesung (24.04.2019): Entwicklung & Plastizität

Vorlesungsinhalt: Reifung des Gehirns; Synapsenbildung; Auswirkungen der Erfahrung auf die Entwicklung; Gehirn in Adoleszenz und Erwachsenenalter; Hirnschädigung und Neuroplastizität; Neuropsychologische Erkrankunge

Diófajták fogékonyságának vizsgálata hazai Xanthomonas arboricola pv. juglandis izolátumokkal

A dió termesztése során az egyik leggyakoribb, legsúlyosabb betegség, a dió xantomonászos betegsége, melyet a Xanthomonas arboricola pv. juglandis baktériumfaj okoz. Az okozott tünetek igen változatosak, és az összes újonnan fejlődött növényi részen megtalálhatók: rügyelhalás, barkafoltosodás (feketedés, görbülés), bibefertőzés, virágzatvizenyősség (zsugorodás, elhalás), levélfoltosodás és torzulás, a hajtásokon a hosszúkás barna-fekete elszíneződés, bélállományig terjedő nekrózis, hajtáselhalás, magbél barnulás, aszalódás. A növénypatogén baktériumok elleni védekezési lehetőségek elég korlátozottak. A rendelkezésre álló növényvédő szerek mellett, nagyon fontos az agrotechnikai módszerek alkalmazása és az ellenálló fajták termesztésbe vonása a kórokozó elleni védekezés során. 2021-ben 11 diófajta termés fogékonyságát vizsgáltuk a Xanthomonas arboricola pv. juglandis kórokozóval szemben mesterséges inokulációval. A fajták eltérő fogékonyságot/ellenállóságot mutattak

Inhibition of the occipital face area modulates the electrophysiological signals of face familiarity: a combined cTBS-EEG study

This project hosts scripts (experimental as well as analytical) of a study investigating the effect of Transcranial Magnetic Stimulation over the Occipital Face Area on Event-Related-Potentials of familiar and unfamiliar faces. The study is going to be published in Cortex. The preprint of the manuscript corresponding to these scripts can be accessed at https://doi.org/10.1101/2020.12.04.41003