The effect of context congruency on fMRI repetition suppression for objects.

The recognition of objects is strongly facilitated when they are presented in the context of other objects (Biederman, 1972). Such contexts facilitate perception and induce expectations of context-congruent objects (Trapp and Bar, 2015). The neural mechanisms underlying these facilitatory effects of context on object processing, however, are not yet fully understood. In the present study, we investigate how context-induced expectations affect subsequent object processing. We used functional magnetic resonance imaging and measured repetition suppression as a proxy for prediction error processing. Participants viewed pairs of alternating or repeated object images which were preceded by context-congruent, context-incongruent or neutral cues. We found a stronger repetition suppression in congruent as compared to incongruent or neutral cues in the object sensitive lateral occipital cortex. Interestingly, this stronger effect was driven by enhanced responses to alternating stimulus pairs in the congruent contexts, rather than by suppressed responses to repeated stimulus pairs, which emphasizes the contribution of surprise-related response enhancement for the context modulation on RS when expectations are violated. In addition, in the congruent condition, we discovered significant functional connectivity between object-responsive and frontal cortical regions, as well as between object-responsive regions and the fusiform gyrus. Our findings indicate that prediction errors, reflected in enhanced brain responses to violated contextual expectations, underlie the facilitating effect of context during object perception.

A link between age, affect, and predictions?

The prevalence of depressive symptoms decreases from late adolescence to middle age adulthood. Furthermore, despite significant losses in motor and cognitive functioning, overall emotional well-being tends to increase with age, and a bias to positive information has been observed multiple times. Several causes have been discussed for this age-related development, such as improvement in emotion regulation, less regret, and higher socioeconomic status. Here, we explore a further explanation. Our minds host mental models that generate predictions about forthcoming events to successfully interact with our physical and social environment. To keep these models faithful, the difference between the predicted and the actual event, that is, the prediction error, is computed. We argue that prediction errors are attenuated in the middle age and older mind, which, in turn, may translate to less negative affect, lower susceptibility to affective disorders, and possibly, to a bias to positive information. Our proposal is primarily linked to perceptual inferences, but may hold as well for higher-level, cognitive, and emotional forms of error processing.

Visual short-term memory load modulates repetition related fMRI signal adaptation.

While several computational models have suggested how predictive coding could be implemented on an algorithmic level, reference to cognitive processes remains rather sparse. A crucial process might be elevating relevant prior information from long-term memory to render it highly accessible for subsequent comparison with sensory input. In many models, visual short-term memory (VSTM) is considered as information from long-term memory in a state of elevated activity. We measured the BOLD signal in face-specific cortical areas using repetition suppression (RS) paradigm. RS has been associated with predictive processing in previous studies. We show that RS within the fusiform face area is significantly attenuated when VSTM is loaded with other, non-facial visual information. Although an unequivocal inference is not possible, the data indicate a role of VSTM for predictive processes as indexed by expectation-related RS.

Predictive brain: Addressing the level of representation by reviewing perceptual hysteresis.

In recent years, the idea that the prediction of sensory input is one of the major computational goals of the nervous system led to the development of several large-scale theories of brain functioning, such as different versions of the Bayesian approach to brain functions, predictive coding theories of cognition and the Free-energy principle. During the years, various empirical phenomena have been re-interpreted within such frames, and have been considered as consequences of predictive processing. Here we focus on perceptual hysteresis, or serial dependence, as an exemplary case. We unravel a potential gap in the predictive frameworks and raise the idea that alternative explanations of this effect can solve this issue, as they address the type of cognitive and neural representations involved.

Bayesian decision-making under stress-preserved weighting of prior and likelihood information.

A rich body of empirical work has addressed the question of how stress changes the way we memorize, learn, and make high-level decisions in complex scenarios. There is evidence that stress also changes the way we perceive the world, indicating influences on decision-making at lower levels. Surprisingly, as of yet, little research has been conducted in this domain. A few studies suggest that under stress, humans tend to eschew existing knowledge, and instead focus on novel input or information from bottom-up. Decision-making in the perceptual domain has been modeled with Bayesian frameworks. Here, existing knowledge about structures and statistics of our environment is referred to as prior, whereas sensory data are termed likelihood. In this study, we directly assessed whether stress, as induced by the socially evaluated cold pressure task (SECPT), would modulate low-level decisions, specifically the weight given to sensory information, and how people reacted to changes in prior and sensory uncertainty. We found that while the stress-inducing procedure successfully elicited subjective stress ratings as well as stress relevant physiological paramters, it did not change participants' average reliance on sensory information. Furthermore, it did not affect participants' sensitivity to changes in prior and sensory uncertainty, with both groups able to detect it and modulate their behavior accordingly, in a way predicted by Bayesian statistics. Our results suggest that, contrary to our predictions, stress may not directly affect lower-level sensory-motor decisions. We discuss the findings in context of time scales of the stress reaction, linked to different neural and functional consequences.

When the rhythm disappears and the mind keeps dancing: sustained effects of attentional entrainment.

Research has demonstrated that the human cognitive system allocates attention most efficiently to a stimulus that occurs in synchrony with an established rhythmic background. However, our environment is dynamic and constantly changing. What happens when rhythms to which our cognitive system adapted disappear? We addressed this question using a visual categorization task comprising emotional and neutral faces. The task was split into three blocks of which the first and the last were completed in silence. The second block was accompanied by an acoustic background rhythm that, for one group of participants, was synchronous with face presentations, and for another group was asynchronous. Irrespective of group, performance improved with background stimulation. Importantly, improved performance extended into the third silent block for the synchronous, but not for the asynchronous group. These data suggest that attentional entrainment resulting from rhythmic environmental regularities disintegrates only gradually after the regularities disappear.

A mind-brain-body dataset of MRI, EEG, cognition, emotion, and peripheral physiology in young and old adults.

We present a publicly available dataset of 227 healthy participants comprising a young (N=153, 25.1±3.1 years, range 20-35 years, 45 female) and an elderly group (N=74, 67.6±4.7 years, range 59-77 years, 37 female) acquired cross-sectionally in Leipzig, Germany, between 2013 and 2015 to study mind-body-emotion interactions. During a two-day assessment, participants completed MRI at 3 Tesla (resting-state fMRI, quantitative T1 (MP2RAGE), T2-weighted, FLAIR, SWI/QSM, DWI) and a 62-channel EEG experiment at rest. During task-free resting-state fMRI, cardiovascular measures (blood pressure, heart rate, pulse, respiration) were continuously acquired. Anthropometrics, blood samples, and urine drug tests were obtained. Psychiatric symptoms were identified with Standardized Clinical Interview for DSM IV (SCID-I), Hamilton Depression Scale, and Borderline Symptoms List. Psychological assessment comprised 6 cognitive tests as well as 21 questionnaires related to emotional behavior, personality traits and tendencies, eating behavior, and addictive behavior. We provide information on study design, methods, and details of the data. This dataset is part of the larger MPI Leipzig Mind-Brain-Body database.

Humans show a higher preference for stimuli that are predictive relative to those that are predictable.

Recent studies suggest that humans prefer information that is linked to the process of prediction. Yet it remains to be specified whether preference judgments are biased to information that can be predicted, or information that enables to predict. We here use a serial reaction time task to disentangle these two options. In a first learning phase, participants were exposed to a continuous stream of arbitrary shapes while performing a go/no-go task. Embedded in this stream were hidden pairs of go-stimuli (e.g., shape A was always followed by shape B). Data show faster reaction times to predictable shapes (i.e., shape B) as compared to random and predictive shapes (i.e., shape A), indicating that participants learned the regularities and anticipated upcoming information. Importantly, in a subsequent, unannounced forced-choice preference task, the shapes that were predictive of others were significantly more preferred over random shapes than shapes that could be predicted. Because both the reaction time benefit in the learning phase and the effect in the preference phase could be considered rather small, we studied the relation between both. Interestingly, the preference correlated with the reaction time benefit from the learning phase. A closer look at this correlation further suggested that the difference in preference was only observed when participants picked up the contingencies between predictive and predictable shapes. This study adds evidence to the idea that prediction processes are not only fundamental for cognition, but contribute to the way we evaluate our external world.

Neuroimaging results suggest the role of prediction in cross-domain priming.

The repetition of a stimulus leads to shorter reaction times as well as to the reduction of neural activity. Previous encounters with closely related stimuli (primes) also lead to faster and often to more accurate processing of subsequent stimuli (targets). For instance, if the prime is a name, and the target is a face, the recognition of a persons' face is facilitated by prior presentation of his/her name. A possible explanation for this phenomenon is that the prime allows predicting the occurrence of the target. To the best of our knowledge, so far, no study tested the neural correlates of such cross-domain priming with fMRI. To fill this gap, here we used names of famous persons as primes, and congruent or incongruent faces as targets. We found that congruent primes not only reduced RT, but also lowered the BOLD signal in bilateral fusiform (FFA) and occipital (OFA) face areas. This suggests that semantic information affects not only behavioral performance, but also neural responses in relatively early processing stages of the occipito-temporal cortex. We interpret our results in the framework of predictive coding theories.

Stressful Events as Teaching Signals for the Brain.

Stressful events are better remembered than mundane events. We explain this advantage by reconceptualizing stress in terms of cumulative prediction errors (PEs) that promote rapid learning of events. This proposal integrates the effects of stress on perception and memory, and provides exciting new perspectives for research on stress and cognition.

Integrating predictive frameworks and cognitive models of face perception.

The idea of a "predictive brain"-that is, the interpretation of internal and external information based on prior expectations-has been elaborated intensely over the past decade. Several domains in cognitive neuroscience have embraced this idea, including studies in perception, motor control, language, and affective, social, and clinical neuroscience. Despite the various studies that have used face stimuli to address questions related to predictive processing, there has been surprisingly little connection between this work and established cognitive models of face recognition. Here we suggest that the predictive framework can serve as an important complement of established cognitive face models. Conversely, the link to cognitive face models has the potential to shed light on issues that remain open in predictive frameworks.

Associated Information Increases Subjective Perception of Duration.

Our sense of time is prone to various biases. For instance, one factor that can dilate an event's perceived duration is the violation of predictions; when a series of repeated stimuli is interrupted by an unpredictable oddball. On the other hand, when the probability of a repetition itself is manipulated, predictable conditions can also increase estimated duration. This suggests that manipulations of expectations have different or even opposing effects on time perception. In previous studies, expectations were generated because stimuli were repeated or because the likelihood of a sequence or a repetition was varied. In the natural environment, however, expectations are often built via associative processes, for example, the context of a kitchen promotes the expectation of plates, appliances, and other associated objects. Here, we manipulated such association-based expectations by using oddballs that were either contextually associated or nonassociated with the standard items. We find that duration was more strongly overestimated for contextually associated oddballs. We reason that top-down attention is biased toward associated information, and thereby dilates subjective duration for associated oddballs. Based on this finding, we propose an interplay between top-down attention and predictive processing in the perception of time.

Predicting Affective Information - An Evaluation of Repetition Suppression Effects.

Both theoretical proposals and empirical studies suggest that the brain interprets sensory input based on expectations to mitigate computational burden. However, as social beings, much of sensory input is affectively loaded - e.g., the smile of a partner, the critical voice of a boss, or the welcoming gesture of a friend. Given that affective information is highly complex and often ambiguous, building up expectations of upcoming affective sensory input may greatly contribute to its rapid and efficient processing. This review points to the role of affective information in the context of the 'predictive brain'. It particularly focuses on repetition suppression (RS) effects that have recently been linked to prediction processes. The findings are interpreted as evidence for more pronounced prediction processes with affective material. Importantly, it is argued that bottom-up attention inflates the neural RS effect, and because affective stimuli tend to attract more bottom-up attention, it thereby particularly overshadows the magnitude of RS effects for this information. Finally, anxiety disorders, such as social phobia, are briefly discussed as manifestations of modulations in affective prediction.

Prior probability modulates anticipatory activity in category-specific areas.

Bayesian models are currently a dominant framework for describing human information processing. However, it is not clear yet how major tenets of this framework can be translated to brain processes. In this study, we addressed the neural underpinning of prior probability and its effect on anticipatory activity in category-specific areas. Before fMRI scanning, participants were trained in two behavioral sessions to learn the prior probability and correct order of visual events within a sequence. The events of each sequence included two different presentations of a geometric shape and one picture of either a house or a face, which appeared with either a high or a low likelihood. Each sequence was preceded by a cue that gave participants probabilistic information about which items to expect next. This allowed examining cue-related anticipatory modulation of activity as a function of prior probability in category-specific areas (fusiform face area and parahippocampal place area). Our findings show that activity in the fusiform face area was higher when faces had a higher prior probability. The finding of a difference between levels of expectations is consistent with graded, probabilistically modulated activity, but the data do not rule out the alternative explanation of a categorical neural response. Importantly, these differences were only visible during anticipation, and vanished at the time of stimulus presentation, calling for a functional distinction when considering the effects of prior probability. Finally, there were no anticipatory effects for houses in the parahippocampal place area, suggesting sensitivity to stimulus material when looking at effects of prediction.

Switching between hands in a serial reaction time task: a comparison between young and old adults.

Healthy aging is associated with a variety of functional and structural brain alterations. These age-related brain alterations have been assumed to negatively impact cognitive and motor performance. Especially important for the execution of everyday activities in older adults (OA) is the ability to perform movements that depend on both hands working together. However, bimanual coordination is typically deteriorated with increasing age. Hence, a deeper understanding of such age-related brain-behavior alterations might offer the opportunity to design future interventional studies in order to delay or even prevent the decline in cognitive and/or motor performance over the lifespan. Here, we examined to what extent the capability to acquire and maintain a novel bimanual motor skill is still preserved in healthy OA as compared to their younger peers (YA). For this purpose, we investigated performance of OA (n = 26) and YA (n = 26) in a bimanual serial reaction time task (B-SRTT), on two experimental sessions, separated by 1 week. We found that even though OA were generally slower in global response times, they showed preserved learning capabilities in the B-SRTT. However, sequence specific learning was more pronounced in YA as compared to OA. Furthermore, we found that switching between hands during B-SRTT learning trials resulted in increased response times (hand switch costs), a phenomenon that was more pronounced in OA. These hand switch costs were reduced in both groups over the time course of learning. More interestingly, there were no group differences in hand switch costs on the second training session. These results provide novel evidence that bimanual motor skill learning is capable of reducing age-related deficits in hand switch costs, a finding that might have important implications to prevent the age-related decline in sensorimotor function.

Identifying neural correlates of visual consciousness with ALE meta-analyses.

Neural correlates of consciousness (NCC) have been a topic of study for nearly two decades. In functional imaging studies, several regions have been proposed to constitute possible candidates for NCC, but as of yet, no quantitative summary of the literature on NCC has been done. The question whether single (striate or extrastriate) regions or a network consisting of extrastriate areas that project directly to fronto-parietal regions are necessary and sufficient neural correlates for visual consciousness is still highly debated [e.g., Rees et al., 2002, Nat Rev. Neurosci 3, 261-270; Tong, 2003, Nat Rev. Neurosci 4, 219-229]. The aim of this work was to elucidate this issue and give a synopsis of the present state of the art by conducting systematic and quantitative meta-analyses across functional magnetic resonance imaging (fMRI) studies using several standard paradigms for conscious visual perception. In these paradigms, consciousness is operationalized via perceptual changes, while the visual stimulus remains invariant. An activation likelihood estimation (ALE) meta-analysis was performed, representing the best approach for voxel-wise meta-analyses to date. In addition to computing a meta-analysis across all paradigms, separate meta-analyses on bistable perception and masking paradigms were conducted to assess whether these paradigms show common or different NCC. For the overall meta-analysis, we found significant clusters of activation in inferior and middle occipital gyrus; fusiform gyrus; inferior temporal gyrus; caudate nucleus; insula; inferior, middle, and superior frontal gyri; precuneus; as well as in inferior and superior parietal lobules. These results suggest a subcortical-extrastriate-fronto-parietal network rather than a single region that constitutes the necessary NCC. The results of our exploratory paradigm-specific meta-analyses suggest that this subcortical-extrastriate-fronto-parietal network might be differentially activated as a function of the paradigms used to probe for NCC.

Prediction, context, and competition in visual recognition.

Perception is substantially facilitated by top-down influences, typically seen as predictions. Here, we outline that the process is competitive in nature, in that sensory input initially activates multiple possible interpretations, or perceptual hypotheses, of its causes. This raises the question of how the selection of the correct interpretation from among those multiple hypotheses is achieved. We first review previous findings in support of such a competitive nature of perceptual processing, and then propose which neural regions might provide a platform for rising and using expectations to resolve this competition. Specifically, we propose that it is the rapid extraction and top-down dissemination of a global context signal from the frontal cortices, particularly the orbitofrontal cortex, that affords the quick and reliable resolution of the initial competition among likely alternatives toward a singular percept.

Human preferences are biased towards associative information.

There is ample evidence that the brain generates predictions that help interpret sensory input. To build such predictions the brain capitalizes upon learned statistical regularities and associations (e.g., "A" is followed by "B"; "C" appears together with "D"). The centrality of predictions to mental activities gave rise to the hypothesis that associative information with predictive value is perceived as intrinsically valuable. Such value would ensure that this information is proactively searched for, thereby promoting certainty and stability in our environment. We therefore tested here whether, all else being equal, participants would prefer stimuli that contained more rather than less associative information. In Experiments 1 and 2 we used novel, meaningless visual shapes and showed that participants preferred associative shapes over shapes that had not been associated with other shapes during training. In Experiment 3 we used pictures of real-world objects and again demonstrated a preference for stimuli that elicit stronger associations. These results support our proposal that predictive information is affectively tagged, and enhance our understanding of the formation of everyday preferences.

Different neural capacity limitations for articulatory and non-articulatory maintenance of verbal information.

Many studies have demonstrated attenuated verbal working memory (WM) under articulatory suppression. However, performance is not completely abolished, suggesting a less efficient, non-articulatory mechanism for the maintenance of verbal information. The neural causes for the reduced efficiency of such a putative complementary maintenance system have not yet been addressed. The present study was conducted to fill this gap. Subjects performed a Sternberg task (a) under articulatory maintenance at low, high, and supracapacity set sizes and (b) under non-articulatory maintenance at low and high set sizes. With functional magnetic resonance imaging, set-size related increases in activity were compared between subvocal articulatory rehearsal and non-articulatory maintenance. First, the results replicate previous findings showing different networks underlying these two maintenance strategies. Second, activation of all key nodes of the articulatory maintenance network increased with the amount of memorized information, showing no plateau at high set sizes. In contrast, for non-articulatory maintenance, there was evidence for a plateau at high set sizes in all relevant areas of the network. Third, for articulatory maintenance, the non-articulatory maintenance network was additionally recruited at supracapacity set sizes, presumably to assist processing in this highly demanding condition. This is the first demonstration of differential neural bottlenecks for articulatory and non-articulatory maintenance. This study adds to our understanding of the performance differences between these two strategies supporting verbal WM.