Decoding of Working Memory Contents in Auditory Cortex Is Not Distractor-Resistant.

Working memory enables the temporary storage of relevant information in the service of behavior. Neuroimaging studies have suggested that sensory cortex is involved in maintaining contents in working memory. This raised the question of how sensory regions maintain memory representations during the exposure to distracting stimuli. Multivariate pattern analysis of fMRI signals in visual cortex has shown that the contents of visual working memory could be decoded concurrently with passively viewed distractors. The present fMRI study tested whether this finding extends to auditory working memory and to active distractor processing. We asked participants to memorize the pitch of a target sound and to compare it with a probe sound presented after a 13 s delay period. In separate conditions, we compared a blank delay phase (no distraction) with either passive listening to, or active processing of, an auditory distractor presented throughout the memory delay. Consistent with previous reports, pitch-specific memory information could be decoded in auditory cortex during the delay in trials without distraction. In contrast, decoding of target sounds in early auditory cortex dropped to chance level during both passive and active distraction. This was paralleled by memory performance decrements under distraction. Extending the analyses beyond sensory cortex yielded some evidence for memory content-specific activity in inferior frontal and superior parietal cortex during active distraction. In summary, while our findings question the involvement of early auditory cortex in the maintenance of distractor-resistant working memory contents, further research should elucidate the role of hierarchically higher regions.SIGNIFICANCE STATEMENT Information about sensory features held in working memory can be read out from hemodynamic activity recorded in human sensory cortices. Moreover, visual cortex can in parallel store visual content and process newly incoming, task-irrelevant visual input. The present study investigated the role of auditory cortex for working memory maintenance under distraction. While memorized sound frequencies could be decoded in auditory cortex in the absence of distraction, auditory distraction during the delay phase impaired memory performance and prevented decoding of information stored in working memory. Apparently, early auditory cortex is not sufficient to represent working memory contents under distraction that impairs performance. However, exploratory analyses indicated that, under distraction, higher-order frontal and parietal regions might contribute to content-specific working memory storage.

Decoding Concurrent Representations of Pitch and Location in Auditory Working Memory.

Multivariate analyses of hemodynamic signals serve to identify the storage of specific stimulus contents in working memory (WM). Representations of visual stimuli have been demonstrated both in sensory regions and in higher cortical areas. While previous research has typically focused on the WM maintenance of a single content feature, it remains unclear whether two separate features of a single object can be decoded concurrently. Also, much less evidence exists for representations of auditory compared with visual stimulus features. To address these issues, human participants had to memorize both pitch and perceived location of one of two sample sounds. After a delay phase, they were asked to reproduce either pitch or location. At recall, both features showed comparable levels of discriminability. Region of interest (ROI)-based decoding of functional magnetic resonance imaging (fMRI) data during the delay phase revealed feature-selective activity for both pitch and location of a memorized sound in auditory cortex and superior parietal lobule. The latter region showed higher decoding accuracy for location than pitch. In addition, location could be decoded from angular and supramarginal gyrus and both superior and inferior frontal gyrus. The latter region also showed a trend for decoding of pitch. We found no region exclusively coding pitch memory information. In summary, the present study yielded evidence for concurrent representations of pitch and location of a single object both in sensory cortex and in hierarchically higher regions, pointing toward representation formats that enable feature integration within the same anatomic brain regions.SIGNIFICANCE STATEMENT Decoding of hemodynamic signals serves to identify brain regions involved in the storage of stimulus-specific information in working memory (WM). While to-be-remembered information typically consists of several features, most previous investigations have focused on the maintenance of one memorized feature belonging to one visual object. The present study assessed the concurrent storage of two features of the same object in auditory WM. We found that both pitch and location of memorized sounds were decodable both in early sensory areas, in higher-level superior parietal cortex and, to a lesser extent, in inferior frontal cortex. While auditory cortex is known to process different features in parallel, their concurrent representation in parietal regions may support the integration of object features in WM.

The neural computation of human prosocial choices in complex motivational states.

Motives motivate human behavior. Most behaviors are driven by more than one motive, yet it is unclear how different motives interact and how such motive combinations affect the neural computation of the behaviors they drive. To answer this question, we induced two prosocial motives simultaneously (multi-motive condition) and separately (single motive conditions). After the different motive inductions, participants performed the same choice task in which they allocated points in favor of the other person (prosocial choice) or in favor of themselves (egoistic choice). We used fMRI to assess prosocial choice-related brain responses and drift diffusion modeling to specify how motive combinations affect individual components of the choice process. Our results showed that the combination of the two motives in the multi-motive condition increased participants' choice biases prior to the behavior itself. On the neural level, these changes in initial prosocial bias were associated with neural responses in the bilateral dorsal striatum. In contrast, the efficiency of the prosocial decision process was comparable between the multi-motive and the single-motive conditions. These findings provide insights into the computation of prosocial choices in complex motivational states, the motivational setting that drives most human behaviors.

Improving audio-visual temporal perception through training enhances beta-band activity.

Multisensory integration strongly depends on the temporal proximity between two inputs. In the audio-visual domain, stimulus pairs with delays up to a few hundred milliseconds can be perceived as simultaneous and integrated into a unified percept. Previous research has shown that the size of this temporal window of integration can be narrowed by feedback-guided training on an audio-visual simultaneity judgment task. Yet, it has remained uncertain how the neural network that processes audio-visual asynchronies is affected by the training. In the present study, participants were trained on a 2-interval forced choice audio-visual simultaneity judgment task. We recorded their neural activity with magnetoencephalography in response to three different stimulus onset asynchronies (0 ms, each participant's individual binding window, 300 ms) before, and one day following training. The Individual Window stimulus onset asynchrony condition was derived by assessing each participant's point of subjective simultaneity. Training improved performance in both asynchronous stimulus onset conditions (300 ms, Individual Window). Furthermore, beta-band amplitude (12-30 Hz) increased from pre-compared to post-training sessions. This increase moved across central, parietal, and temporal sensors during the time window of 80-410 ms post-stimulus onset. Considering the putative role of beta oscillations in carrying feedback from higher to lower cortical areas, these findings suggest that enhanced top-down modulation of sensory processing is responsible for the improved temporal acuity after training. As beta oscillations can be assumed to also preferentially support neural communication over longer conduction delays, the widespread topography of our effect could indicate that training modulates not only processing within primary sensory cortex, but rather the communication within a large-scale network.

Significance of Beta-Band Oscillations in Autism Spectrum Disorders During Motor Response Inhibition Tasks: A MEG Study.

In Autism Spectrum Disorders (ASD), impaired response inhibition and lack of adaptation are hypothesized to underlie core ASD symptoms, such as social communication and repetitive, stereotyped behavior. Thus, the aim of the present study was to compare neural correlates of inhibition, post-error adaptation, and reaction time variability in ASD and neuro-typical control (NTC) participants by investigating possible differences in error-related changes of oscillatory MEG activity. Twelve male NTC (mean age 20.3 ± 3.7) and fourteen male patients with ASD (mean age 17.8 ± 2.9) were included in the analysis. Subjects with ASD showed increased error-related reaction time variability. MEG analysis revealed decreased beta power in the ASD group in comparison to the NTC group over the centro-parietal channels in both, the pre-stimulus and post-response interval. In the ASD group, mean centro-parietal beta power negatively correlated with dimensional autism symptoms. In both groups, false alarms were followed by an early increase in temporo-frontal theta to alpha power; and by a later decrease in alpha to beta power at central and posterior sensors. Single trial correlations were additionally studied in the ASD group, who showed a positive correlation of pre-stimulus beta power with post-response theta, alpha, and beta power, particularly after hit trials. On a broader scale, the results deliver important insights into top-down control deficits that may relate to core symptoms observed in ASD.

Correction to: Psychosocial distress in acute cancer patients assessed with an expert rating scale.

The article "Psychosocial distress in acute cancer patients assessed with an expert rating scale".

[Medical Psychology and Medical Sociology in Transition - Review and Perspectives of the two Disciplines in Germany]. / Medizinische Psychologie und Medizinische Soziologie im Wandel ­ Bestandsaufnahme und Perspektiven der beiden Fächer in Deutschland.

AIM OF THE STUDY: Through the Master Plan for Medical Studies 2020 and the development of the National Competence-Based Learning Target Catalogue Medicine (NKLM), significant changes in university medicine were started. The aim of the study was a systematic analysis of the state and perspectives of the disciplines of medical psychology and sociology at the medical faculties in Germany. METHODOLOGY: An online survey was conducted on 5 topics (structure, teaching, research, care, perspectives). 46 departments and institutes of medical psychology and sociology were invited to the survey. RESULTS: 40 of the 46 contacted institutions have called up the online questionnaire, 35 have answered in full (return: 76.1%). 77% of the institutions are autonomous. In the median, the institutions have 15 employees (range: 1 to 149). 9 universities have established a model curriculum. More than half of the institutions use and train simulation patients. The main research priorities are clinical research, health care research, neuroscience and classical medical psychology or sociological research topics. The institutions receive primarily public funding and publish 19 publications (80% international, median) each year. Publication opportunities are considered "satisfactory" by 54% of institutions (2003: 44%), and by 29% as "very satisfactory" (2003: 21%). 9 out of 27 medical psychology institutes provide clinical services to patients and relatives with mental or chronic physical illness. Almost half of the institutions expect the Master Plan 2020 to further increase the relevance of the subjects. DISCUSSION: Since 2003 there has been a substantial increase in scientific staff, third-party funding and publications. The sites show a pronounced heterogeneity in terms of size and equipment, which leads to an imbalance in terms of teaching and research as well as clinical services. CONCLUSION: The subjects of medical psychology and medical sociology have developed very heterogeneously in terms of independence, size, equipment and possibilities at the various faculties in Germany. Therefore, it is very important in the future that the 2 disciplines intensify the dialogue with each other and also with other psychosocial disciplines in order to influence the current development regarding NKLM and Master Plan 2020 constructively. On the one hand, this calls for an expansion of disadvantaged institutions and a consolidation of the existing autonomous institutions.

Differential trajectories of memory quality and guessing across sequential reports from working memory.

Working memory enables the storage of few items for a short period of time. Previous research has shown that items in working memory cannot be accessed equally well, indicating that they are held in at least two different states with different capacity limitations. However, it is unclear whether differences between states are due to limitations of the number of items that can be stored, or the quality with which items are stored. We employed a sequential whole-report procedure where participants reported the remembered orientation of each of two or four encoded Gabor patches. In addition, they rated their memory confidence prior to each report. Participants performed 600 trials per condition, allowing us to obtain reliable subjective ratings and estimates of precision, guessing, and misreport using a mixture model, separately for each sequential report. Different measures of memory quality consistently showed discontinuous trajectories across reports with a steep drop from the first to the second remembered item but only slight decreases thereafter. In contrast, both reported and modeled guessing changed continuously across reports. Our results support the notion of two states in working memory and show that they are distinguished by memory quality rather than quantity.

Predictable information in neural signals during resting state is reduced in autism spectrum disorder.

The neurophysiological underpinnings of the nonsocial symptoms of autism spectrum disorder (ASD) which include sensory and perceptual atypicalities remain poorly understood. Well-known accounts of less dominant top-down influences and more dominant bottom-up processes compete to explain these characteristics. These accounts have been recently embedded in the popular framework of predictive coding theory. To differentiate between competing accounts, we studied altered information dynamics in ASD by quantifying predictable information in neural signals. Predictable information in neural signals measures the amount of stored information that is used for the next time step of a neural process. Thus, predictable information limits the (prior) information which might be available for other brain areas, for example, to build predictions for upcoming sensory information. We studied predictable information in neural signals based on resting-state magnetoencephalography (MEG) recordings of 19 ASD patients and 19 neurotypical controls aged between 14 and 27 years. Using whole-brain beamformer source analysis, we found reduced predictable information in ASD patients across the whole brain, but in particular in posterior regions of the default mode network. In these regions, epoch-by-epoch predictable information was positively correlated with source power in the alpha and beta frequency range as well as autocorrelation decay time. Predictable information in precuneus and cerebellum was negatively associated with nonsocial symptom severity, indicating a relevance of the analysis of predictable information for clinical research in ASD. Our findings are compatible with the assumption that use or precision of prior knowledge is reduced in ASD patients.

Stability of BDNF in Human Samples Stored Up to 6 Months and Correlations of Serum and EDTA-Plasma Concentrations.

Brain-derived neurotrophic factor (BDNF), an important neural growth factor, has gained growing interest in neuroscience, but many influencing physiological and analytical aspects still remain unclear. In this study we assessed the impact of storage time at room temperature, repeated freeze/thaw cycles, and storage at -80 °C up to 6 months on serum and ethylenediaminetetraacetic acid (EDTA)-plasma BDNF. Furthermore, we assessed correlations of serum and plasma BDNF concentrations in two independent sets of samples. Coefficients of variations (CVs) for serum BDNF concentrations were significantly lower than CVs of plasma concentrations (n = 245, p = 0.006). Mean serum and plasma concentrations at all analyzed time points remained within the acceptable change limit of the inter-assay precision as declared by the manufacturer. Serum and plasma BDNF concentrations correlated positively in both sets of samples and at all analyzed time points of the stability assessment (r = 0.455 to rs = 0.596; p < 0.004). In summary, when considering the acceptable change limit, BDNF was stable in serum and in EDTA-plasma up to 6 months. Due to a higher reliability, we suggest favoring serum over EDTA-plasma for future experiments assessing peripheral BDNF concentrations.

Activity in human visual and parietal cortex reveals object-based attention in working memory.

Visual attention enables observers to select behaviorally relevant information based on spatial locations, features, or objects. Attentional selection is not limited to physically present visual information, but can also operate on internal representations maintained in working memory (WM) in service of higher-order cognition. However, only little is known about whether attention to WM contents follows the same principles as attention to sensory stimuli. To address this question, we investigated in humans whether the typically observed effects of object-based attention in perception are also evident for object-based attentional selection of internal object representations in WM. In full accordance with effects in visual perception, the key behavioral and neuronal characteristics of object-based attention were observed in WM. Specifically, we found that reaction times were shorter when shifting attention to memory positions located on the currently attended object compared with equidistant positions on a different object. Furthermore, functional magnetic resonance imaging and multivariate pattern analysis of visuotopic activity in visual (areas V1-V4) and parietal cortex revealed that directing attention to one position of an object held in WM also enhanced brain activation for other positions on the same object, suggesting that attentional selection in WM activates the entire object. This study demonstrated that all characteristic features of object-based attention are present in WM and thus follows the same principles as in perception.

Actively but not passively synchronized motor activity amplifies predictive timing.

Previous studies have shown that the effect of temporal predictability of presented stimuli on attention allocation is enhanced by auditory-motor synchronization (AMS). The present P300 event-related potential study (N=20) investigated whether this enhancement depends on the process of actively synchronizing one's motor output with the acoustic input or whether a passive state of auditory-motor synchrony elicits the same effect. Participants silently counted frequency deviants in sequences of pure tones either during a physically inactive control condition or while pedaling on a cycling ergometer. Tones were presented either at fixed or variable intervals. In addition to the pedaling conditions with fixed or variable stimulation, there was a third condition in which stimuli were adaptively presented in sync with the participants' spontaneous pedaling. We replicated the P300 enhancement for fixed versus variable stimulation and the amplification of this effect by AMS. Synchronization performance correlated positively with P300 amplitude in the fixed stimulation condition. Most interestingly, P300 amplitude was significantly reduced for the passive synchronization condition by adaptive stimulus presentation as compared to the fixed stimulation condition. For the first time we thus provide evidence that it is not the passive state of (even perfect) auditory-motor synchrony that facilitates attention allocation during AMS but rather the active process of synchronizing one's movements with external stimuli.

Temporal integration of multisensory stimuli in autism spectrum disorder: a predictive coding perspective.

Recently, a growing number of studies have examined the role of multisensory temporal integration in people with autism spectrum disorder (ASD). Some studies have used temporal order judgments or simultaneity judgments to examine the temporal binding window, while others have employed multisensory illusions, such as the sound-induced flash illusion (SiFi). The SiFi is an illusion created by presenting two beeps along with one flash. Participants perceive two flashes if the stimulus-onset asynchrony (SOA) between the two flashes is brief. The temporal binding window can be measured by modulating the SOA between the beeps. Each of these tasks has been used to compare the temporal binding window in people with ASD and typically developing individuals; however, the results have been mixed. While temporal order and simultaneity judgment tasks have shown little temporal binding window differences between groups, studies using the SiFi have found a wider temporal binding window in ASD compared to controls. In this paper, we discuss these seemingly contradictory findings and suggest that predictive coding may be able to explain the differences between these tasks.

The Effects of Acute Physical Exercise on Memory, Peripheral BDNF, and Cortisol in Young Adults.

In animals, physical activity has been shown to induce functional and structural changes especially in the hippocampus and to improve memory, probably by upregulating the release of neurotrophic factors. In humans, results on the effect of acute exercise on memory are inconsistent so far. Therefore, the aim of the present study was to assess the effects of a single bout of physical exercise on memory consolidation and the underlying neuroendocrinological mechanisms in young adults. Participants encoded a list of German-Polish vocabulary before exercising for 30 minutes with either high intensity or low intensity or before a relaxing phase. Retention of the vocabulary was assessed 20 minutes after the intervention as well as 24 hours later. Serum BDNF and salivary cortisol were measured at baseline, after learning, and after the intervention. The high-intensity exercise group showed an increase in BDNF and cortisol after exercising compared to baseline. Exercise after learning did not enhance the absolute number of recalled words. Participants of the high-intensity exercise group, however, forgot less vocabulary than the relaxing group 24 hours after learning. There was no robust relationship between memory scores and the increase in BDNF and cortisol, respectively, suggesting that further parameters have to be taken into account to explain the effects of exercise on memory in humans.

Attentional modulation of the inner ear: a combined otoacoustic emission and EEG study.

Attending to a single stimulus in a complex multisensory environment requires the ability to select relevant information while ignoring distracting input. The underlying mechanism and involved neuronal levels of this attentional gain control are still a matter of debate. Here, we investigated the influence of intermodal attention on different levels of auditory processing in humans. It is known that the activity of the cochlear amplifier can be modulated by efferent neurons of the medial olivocochlear complex. We used distortion product otoacoustic emission (DPOAE) measurements to monitor cochlear activity during an intermodal cueing paradigm. Simultaneously, central auditory processing was assessed by electroencephalography (EEG) with a steady-state paradigm targeting early cortical responses and analysis of alpha oscillations reflecting higher cognitive control of attentional modulation. We found effects of selective attention at all measured levels of the auditory processing: DPOAE levels differed significantly between periods of visual and auditory attention, showing a reduction during visual attention, but no change during auditory attention. Primary auditory cortex activity, as measured by the auditory steady-state response (ASSR), differed between conditions, with higher ASSRs during auditory than visual attention. Furthermore, the analysis of cortical oscillatory activity revealed increased alpha power over occipitoparietal and frontal regions during auditory compared with visual attention, putatively reflecting suppression of visual processing. In conclusion, this study showed both enhanced processing of attended acoustic stimuli in early sensory cortex and reduced processing of distracting input, both at higher cortical levels and at the most peripheral level of the hearing system, the cochlea.

The association between gray matter volume and reading proficiency: a longitudinal study of beginning readers.

Neural systems involved in the processing of written language have been identified by a number of functional imaging studies. Structural changes in cortical anatomy that occur in the course of literacy acquisition, however, remain largely unknown. Here, we follow elementary school children over their first 2 years of formal reading instruction and use tensor-based morphometry to relate reading proficiency to cortical volume at baseline and follow-up measurement as well as to intraindividual longitudinal volume development between the two measurement time points. A positive relationship was found between baseline gray matter volume in the left superior temporal gyrus and subsequent changes in reading proficiency. Furthermore, a negative relationship was found between reading proficiency at the second measurement time point and intraindividual cortical volume development in the inferior parietal lobule and the precentral and postcentral gyri of the left hemisphere. These results are interpreted as evidence that reading acquisition is associated with preexisting structural differences as well as with experience-dependent structural changes involving dendritic and synaptic pruning.

fMRI characterization of visual working memory recognition.

Encoding and maintenance of information in visual working memory have been extensively studied, highlighting the crucial and capacity-limiting role of fronto-parietal regions. In contrast, the neural basis of recognition in visual working memory has remained largely unspecified. Cognitive models suggest that recognition relies on a matching process that compares sensory information with the mental representations held in memory. To characterize the neural basis of recognition we varied both the need for recognition and the degree of similarity between the probe item and the memory contents, while independently manipulating memory load to produce load-related fronto-parietal activations. fMRI revealed a fractionation of working memory functions across four distributed networks. First, fronto-parietal regions were activated independent of the need for recognition. Second, anterior parts of load-related parietal regions contributed to recognition but their activations were independent of the difficulty of matching in terms of sample-probe similarity. These results argue against a key role of the fronto-parietal attention network in recognition. Rather the third group of regions including bilateral temporo-parietal junction, posterior cingulate cortex and superior frontal sulcus reflected demands on matching both in terms of sample-probe-similarity and the number of items to be compared. Also, fourth, bilateral motor regions and right superior parietal cortex showed higher activation when matching provided clear evidence for a decision. Together, the segregation between the well-known fronto-parietal activations attributed to attentional operations in working memory from those regions involved in matching supports the theoretical view of separable attentional and mnemonic contributions to working memory. Yet, the close theoretical and empirical correspondence to perceptual decision making may call for an explicit consideration of decision making mechanisms in conceptions of working memory.

Treadmill walking during vocabulary encoding improves verbal long-term memory.

Moderate physical activity improves various cognitive functions, particularly when it is applied simultaneously to the cognitive task. In two psychoneuroendocrinological within-subject experiments, we investigated whether very low-intensity motor activity, i.e. walking, during foreign-language vocabulary encoding improves subsequent recall compared to encoding during physical rest. Furthermore, we examined the kinetics of brain-derived neurotrophic factor (BDNF) in serum and salivary cortisol. Previous research has associated both substances with memory performance.In both experiments, subjects performed better when they were motorically active during encoding compared to being sedentary. BDNF in serum was unrelated to memory performance. In contrast we found a positive correlation between salivary cortisol concentration and the number of correctly recalled items. In summary, even very light physical activity during encoding is beneficial for subsequent recall.

Auditory-motor synchronization facilitates attention allocation.

Temporal predictability of auditory events induces larger P300 amplitudes and shorter P300 latencies compared to stimulus presentation with variable onset asynchronies. This suggests that periodic stimuli lead to neuronal entrainment resulting in a more efficient allocation of attentional resources. Simultaneous synchronized motor activity should facilitate the precise temporal encoding of acoustic sequences. Therefore the current event-related potential study investigated whether embodied stimulus encoding enhances the reported effects of stimulus periodicity. We found that simultaneous pedaling on an ergometer compared to a physically passive situation amplified the predictability effect on the P300 component. Furthermore, the temporal variability of cycling behavior correlated positively with both P300 latency and P300 amplitude. These findings indicate that auditory-motor synchronization enhances the attentional processing of periodical auditory stimuli.