Frank Rösler

Improved auditory spatial tuning in blind humans

Despite reports of improved auditory discrimination capabilities in blind humans and visually deprived animals, there is no general agreement as to the nature or pervasiveness of such compensatory sensory enhancements. Neuroimaging studies have pointed out differences in cerebral organization between blind and sighted humans, but the relationship between these altered cortical activation patterns and auditory sensory acuity remains unclear. Here we compare behavioural and electrophysiological indices of spatial tuning within central and peripheral auditory space in congenitally blind and normally sighted but blindfolded adults to test the hypothesis (raised by earlier studies of the effects of auditory deprivation on visual processing,) that the effects of visual deprivation might be more pronounced for processing peripheral sounds. We find that blind participants displayed localization abilities that were superior to those of sighted controls, but only when attending to sounds in peripheral auditory space. Electrophysiological recordings obtained at the same time revealed sharper tuning of early spatial attention mechanisms in the blind subjects. Differences in the scalp distribution of brain electrical activity between the two groups suggest a compensatory reorganization of brain areas in the blind that may contribute to the improved spatial resolution for peripheral sound sources.

Speech processing activates visual cortex in congenitally blind humans

Neurophysiological recordings and neuroimaging data in blind and deaf animals and humans suggest that perceptual functions may be organized differently after sensory deprivation. It has been argued that neural plasticity contributes to compensatory performance in blind humans, such as faster speech processing. The present study employed functional magnetic resonance imaging (fMRI) to map language‐related brain activity in congenitally blind adults. Participants listened to sentences, with either an easy or a more difficult syntactic structure, which were either semantically meaningful or meaningless. Results show that blind adults not only activate classical left‐hemispheric perisylvian language areas during speech comprehension, as did a group of sighted adults, but that they additionally display an activation in the homologueous right‐hemispheric structures and in extrastriate and striate cortex. Both the perisylvian and occipital activity varied as a function of syntactic difficulty and semantic content. The results demonstrate that the cerebral organization of complex cognitive systems such as the language system is significantly shaped by the input available.

Early Vision Impairs Tactile Perception in the Blind

Researchers have known for more than a century that crossing the hands can impair both tactile perception and the execution of appropriate finger movements. Sighted people find it more difficult to judge the temporal order when two tactile stimuli, one applied to either hand, are presented and their hands are crossed over the midline as compared to when they adopt a more typical uncrossed-hands posture. It has been argued that because of the dominant role of vision in motor planning and execution, tactile stimuli are remapped into externally defined coordinates (predominantly determined by visual inputs) that takes longer to achieve when external and body-centered codes (determined primarily by somatosensory/proprioceptive inputs) are in conflict and that involves both multisensory parietal and visual cortex. Here, we show that the performance of late, but not of congenitally, blind people was impaired by crossing the hands. Moreover, we provide the first empirical evidence for superior temporal order judgments (TOJs) for tactile stimuli in the congenitally blind. These findings suggest a critical role of childhood vision in modulating the perception of touch that may arise from the emergence of specific crossmodal links during development.

Event-related brain potentials while encountering semantic and syntactic constraint violations

The objective of the present study was to delineate brain-electrical correlates of semantic and syntactic integration processes during language comprehension. Twenty-eight subjects were engaged in a lexical decision task. The target item (a legal word or a pseudo word) was always preceded by a prime consisting of a sentence fragment that provided a particular context. With respect to the prime a word target could be either a correct completion, a violation of a semantic selection restriction, or a violation of a syntactic subcategorization rule. An N400-like wave was elicited by both types of deviations. Syntactic anomalies evoked a negative shift predominantly over the anterior scalp with a preponderance over the left hemisphere, while semantic anomalies were accompanied by a much more widespread negativity with the maximum over posterior temporal areas. The amplitude of the semantic vie lation effect was found to be related to the strength of the priming constraints. The topographic difference is consistent with the idea that syntactic and semantic aspects of comprehension are handled by different neural subsystems.

Brain Activation Modulated by the Comprehension of Normal and Pseudo-word Sentences of Different Processing Demands: A Functional Magnetic Resonance Imaging Study

Recent data from lesion and brain imaging studies have questioned the well-established assumption of a close functional-anatomic link between syntax and Brocas area and semantics and Wernickes area. In the present study we used functional magnetic resonance imaging (fMRI) to investigate the neuroanatomical correlates of semantic and syntactic functions and possible interdependencies between the related brain systems. In a completely crossed design we varied syntactic processing demands (easy vs difficult to process word order sequences) and the meaningfulness of sentences (real- vs pseudo-word sentences). In comparison to a backward speech condition we found an activation of the left perisylvian region, including the left inferior frontal cortex and the left superior and middle temporal gyri. Semantic in contrast to pseudo-word sentences elicited a stronger activation in both the anterior and the posterior perisylvian cortex. Syntactic difficulty had its strongest effect within the left inferior frontal region and this effect was more pronounced for semantic than nonsemantic speech. These results suggest that semantic and syntactic language functions are mediated by partly specialized brain systems but that there nevertheless exists a substantial functional overlap of the involved brain structures.

Slow negative brain potentials as reflections of specific modular resources of cognition.

The paper summarizes a series of experiments in which the topography and the amplitude of slow event-related brain potentials (slow ERPs) was studied in cognitive tasks which imposed different amounts of load on functionally distinct processing modules. The results suggest that the topography of slow ERPs reflects the relative activation/inactivation of distinct cortical cell assemblies while the absolute amplitude of the negative maximum seems to reflect how much a particular cell assembly is activated at a particular time. Translated into the terminology of cognitive resource theories one could say that tasks which evoke distinct slow wave patterns draw on independent resources. Likewise, the amplitude of a slow wave pattern could be related to the construct of resource allocation, i.e. the larger the amplitude of a slow wave pattern the more resources of a particular type are allocated to a task. These findings are discussed with respect to possible generator mechanism of slow waves and in relation to possible causes of capacity limitations of the human information processing system.

Event-related potentials during auditory and somatosensory discrimination in sighted and blind human subjects.

The objective of the present study was to test if and to what extent phasic and tonic event-related potentials of the human EEG may reflect phenomena of cortical plasticity. In particular, it was tested if the occipital cortex of blind subjects participates in the processing of non-visual stimuli. To this end, 12 blind and 12 blindfolded sighted subjects were tested in an auditory and a somatosensory discrimination task with 2 levels of discrimination difficulty. Slow and fast event-related potentials were recorded from 18 scalp electrodes. In addition to the negative slow waves found in sighted subjects over frontal and central sites during auditory and somatosensory discrimination, a pronounced negative wave was revealed in the blind also over occipital brain areas. These negative shifts were time-locked to the train of stimuli which had to be monitored with sustained attention, i.e. they rised and resolved with the beginning and the end of a 20-s discrimination time epoch. The P300 complex, on the other hand, which is a slow positive deflection over the posterior part of the scalp and which follows rare and task-relevant events 200-800 ms after stimulus onset was significantly smaller at occipital electrodes in the blind than in the sighted subjects. Combined with neurophysiological and neuronanatomical evidence originating from studies with visually deprived animals, these data suggest that the occipital cortex of blind human subjects is coactivated whenever the system is engaged in a task which requires sustained attention and is less effectively inhibited at the end of a perceptual time epoch. In total, the data cast doubt on the hypothesis that the occipital cortex of blind subjects participates in modality-specific non-visual information processing.

Lifespan development and the brain : The perspective of biocultural co-constructivism

Preface Paul B. Baltes, Patricia A. Reuter-Lorenz and Frank Rosler Part I. Setting the Stage across the Ages of the Lifespan: 1. Prologue: biocultural co-constructivism as a theoretical metascript Paul B. Baltes, Frank Rosler and Patricia A. Reuter-Lorenz 2. Biocultural co-construction of lifespan development Shu-Chen Li Part II. Neuronal Plasticity and Biocultural Co-Construction: Microstructure Meets the Experiential Environment: 3. Neurobehavioral development in the context of biocultural co-constructivism Charles A. Nelson 4. Adult neurogenesis Gerd Kempermann Part III. Neuronal Plasticity and Biocultural Co-Construction: Atypical Brain Architectures: 5. Sensory input-based adaptation and brain architecture Maurice Ptito and Sebastien Desgent 6. Blindness: a source and case of neuronal plasticity Brigitte Roder Part IV. Biocultural Co-Construction: Specific Functions and Domains: 7. Language acquisition: biological versus cultural implications for brain structure Angela D. Friederici and Shirley-Ann Ruschemeyer 8. Reading, writing, and arithmetic in the brain: neural specialization for acquired functions Thad A. Polk and J. Paul Hamilton 9. Emotion, learning, and the brain: from classical conditioning to cultural bias Elizabeth A. Phelps 10. The musical mind: neural tuning and the aesthetic experience Oliver Vitouch Part V. Plasticity and Biocultural Co-Construction in Later Life: 11. Influences of biological and self-initiated factors on brain and cognition in adulthood and aging Lars Nyberg and Lars Backman 12. The aging mind and brain: implications of enduring plasticity for behavioral and cultural change Patricia A. Reuter-Lorenz and Joseph A. Mikels Part VI. Biocultural Co-Construction: From Micro- to Macroenvironments in Larger Cultural Contexts: 13. Characteristics of illiterate and literate cognitive processing: implications of brain-behavior co-constructivism Karl Magnus Petersson and Alexandra Reis 14. The influence of work and occupation on brain development Neil Charness 15. The influence of organized violence and terror on brain and mind: a co-constructive perspective Thomas Elbert, Brigitte Rockstroh, Iris-Tatjana Kolassa, Maggie Schauer and Frank Neuner 16. Co-constructing human engineering technologies in old age: lifespan psychology as a conceptual foundation Ulman Lindenberger and Martin Lovden Part VII. Epilogue: 17. Letters on nature and nurture Onur Gunturkun.

N400 Effects Reflect Activation Spread During Retrieval of Arithmetic Facts

Arithmetic facts are stored in densely interconnected memory networks, and retrieval errors may occur because activation spreads to associated results. We studied the extension of activation spread by means of the so-called N400 effect of the event-related brain potential (ERP). With semantic stimuli, N400 amplitude has proved to be inversely proportional to the amount of activation that originates from a priming context. ERPs were recorded from 61 scalp positions while 16 subjects verified 600 multiplication problems (a × b = c). The solution to each problem could be correct or incorrect. Incorrect solutions were either table related to one of the operands (e.g., 5 × 8 = 32, 24, or 16) or unrelated (e.g., 5 × 8 = 34, 26, or 18), and were either a small, medium, or large numerical distance from the correct product. Our findings suggest that activation spread in an arithmetic memory network is restricted to numbers that are table related to one of the operands and that are numerically plausible.

Early processing stages are modulated when auditory stimuli are presented at an attended moment in time: an event-related potential study.

The present study investigated with event-related potentials whether attending to a moment in time modulates the processing of auditory stimuli at a similar early, perceptual level as attending to a location in space. The participants listened to short (600 ms) and long (1,200 ms) intervals marked by white noise bursts. The task was to attend in alternating runs either to the short or to the long intervals and to respond to rare offset markers that differed in intensity from the frequent standard offset markers. Prior to the to-be-attended moment, a slow negative potential developed over the frontal scalp. Stimuli presented at the attended compared to the unattended moments in time elicited an enhanced N1 and an enhanced posteriorly distributed positivity (300-370 ms). The results show that attention can be flexibly controlled in time and that not only late but also early perceptual processing stages are modulated by attending to a moment in time.