Linda V. Heinemann

Exploring BOLD changes during spatial attention in non-stimulated visual cortex.

Blood oxygen level-dependent (BOLD) responses were measured in parts of primary visual cortex that represented unstimulated visual field regions at different distances from a stimulated central target location. The composition of the visual scene varied by the presence or absence of additional peripheral distracter stimuli. Bottom-up effects were assessed by comparing peripheral activity during central stimulation vs. no stimulation. Top-down effects were assessed by comparing active vs. passive conditions. In passive conditions subjects simply watched the central letter stimuli and in active conditions they had to report occurrence of pre-defined targets in a rapid serial letter stream. Onset of the central letter stream enhanced activity in V1 representations of the stimulated region. Within representations of the periphery activation decreased and finally turned into deactivation with increasing distance from the stimulated location. This pattern was most pronounced in the active conditions and during the presence of peripheral stimuli. Active search for a target did not lead to additional enhancement at areas representing the attentional focus but to a stronger deactivation in the vicinity. Suppressed neuronal activity was also found in the non distracter condition suggesting a top-down attention driven effect. Our observations suggest that BOLD signal decreases in primary visual cortex are modulated by bottom-up sensory-driven factors such as the presence of distracters in the visual field as well as by top-down attentional processes.

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.

Processing of spectral and amplitude envelope of animal vocalizations in the human auditory cortex.

In daily life, we usually identify sounds effortlessly and efficiently. Two properties are particularly salient and of importance for sound identification: the sounds overall spectral envelope and its temporal amplitude envelope. In this study, we aimed at investigating the representation of these two features in the human auditory cortex by using a functional magnetic resonance imaging adaptation paradigm. We presented pairs of sound stimuli derived from animal vocalizations that preserved the time-averaged frequency spectrum of the animal vocalizations and the amplitude envelope. We presented the pairs in four different conditions: (a) pairs with the same amplitude envelope and mean spectral envelope, (b) same amplitude envelope, but different mean spectral envelope, (c) different amplitude envelope, but same mean spectral envelope and (d) both different amplitude envelope and mean spectral envelope. We found fMRI adaptation effects for both the mean spectral envelope and the amplitude envelope of animal vocalizations in overlapping cortical areas in the bilateral superior temporal gyrus posterior to Heschls gyrus. Areas sensitive to the amplitude envelope extended further anteriorly along the lateral superior temporal gyrus in the left hemisphere, while areas sensitive to the spectral envelope extended further anteriorly along the right lateral superior temporal gyrus. Posterior tonotopic areas within the left superior temporal lobe displayed sensitivity for the mean spectrum. Our findings suggest involvement of primary auditory areas in the representation of spectral cues and encoding of general spectro-temporal features of natural sounds in non-primary posterior and lateral superior temporal cortex.

P3b reflects periodicity in linguistic sequences.

Temporal predictability is thought to affect stimulus processing by facilitating the allocation of attentional resources. Recent studies have shown that periodicity of a tonal sequence results in a decreased peak latency and a larger amplitude of the P3b compared with temporally random, i.e., aperiodic sequences. We investigated whether this applies also to sequences of linguistic stimuli (syllables), although speech is usually aperiodic. We compared aperiodic syllable sequences with two temporally regular conditions. In one condition, the interval between syllable onset was fixed, whereas in a second condition the interval between the syllables’ perceptual center (p-center) was kept constant. Event-related potentials were assessed in 30 adults who were instructed to detect irregularities in the stimulus sequences. We found larger P3b amplitudes for both temporally predictable conditions as compared to the aperiodic condition and a shorter P3b latency in the p-center condition than in both other conditions. These findings demonstrate that even in acoustically more complex sequences such as syllable streams, temporal predictability facilitates the processing of deviant stimuli. Furthermore, we provide first electrophysiological evidence for the relevance of the p-center concept in linguistic stimulus processing.

Repetition Enhancement for Frequency-Modulated but Not Unmodulated Sounds: A Human MEG Study

Background Decoding of frequency-modulated (FM) sounds is essential for phoneme identification. This study investigates selectivity to FM direction in the human auditory system. Methodology/Principal Findings Magnetoencephalography was recorded in 10 adults during a two-tone adaptation paradigm with a 200-ms interstimulus-interval. Stimuli were pairs of either same or different frequency modulation direction. To control that FM repetition effects cannot be accounted for by their on- and offset properties, we additionally assessed responses to pairs of unmodulated tones with either same or different frequency composition. For the FM sweeps, N1m event-related magnetic field components were found at 103 and 130 ms after onset of the first (S1) and second stimulus (S2), respectively. This was followed by a sustained component starting at about 200 ms after S2. The sustained response was significantly stronger for stimulation with the same compared to different FM direction. This effect was not observed for the non-modulated control stimuli. Conclusions/Significance Low-level processing of FM sounds was characterized by repetition enhancement to stimulus pairs with same versus different FM directions. This effect was FM-specific; it did not occur for unmodulated tones. The present findings may reflect specific interactions between frequency separation and temporal distance in the processing of consecutive FM sweeps.

Auditory repetition enhancement at short interstimulus intervals for frequency-modulated tones

Frequency-modulated (FM) sweeps are important components of most natural sounds. To examine the processing of these stimuli we applied a two-tone paradigm. Repeated stimulus presentation usually leads to reduced neuronal responses. However, in a former study repetition enhancements which have been observed when FM tones were separated by short interstimulus intervals (ISIs) of ≤200ms. To further investigate this repetition effect in response to FM tones, we recorded magnetoencephalogram (MEG) in humans during the presentation of consecutive FM sweep pairs separated by ISIs between 100 and 600ms. We presented FM sweep pairs in six experimental conditions: a) two upward FM tones, b) two downward FM tones, c) an upward followed by a downward FM tone and d) a downward followed by an upward FM tone. Sequences of single upward and single downward FM tones served as control conditions. N1m amplitude was enhanced for repeated compared with different FM-direction tone pairs. This effect was found for the shortest ISI of 100ms and disappeared at longer ISIs. Furthermore, mean peak latencies in response to the second tone were prolonged in same-direction pairs at the shortest ISI of 100ms. At ISIs ≥300ms slight enhancement effects occurred between 180 and 400ms after the second stimulus. This is in accordance with a previous MEG study from our laboratory which demonstrated an enhancement effect for sustained fields at latencies of 150-350ms after the second stimulus for same compared to different FM tone pairs separated by an ISI of 200ms.

Burnout Research: Emergence and Scientific Investigation of a Contested Diagnosis

Even though burnout is one of the most widely discussed mental health problems in today’s society, it is still disputed and not officially recognized as a mental disorder in most countries. In the tradition of the social study of science, the objective of this article is to analyze how burnout has been investigated in the health sciences in the past four decades, and how this has influenced the ways burnout is understood today. We conducted an extensive quantitative and qualitative literature analysis on all publications on burnout listed in PubMed until 2011. We show that the number of publications on burnout increased considerably over the past 40 years, and identified six categories into which each study can be grouped. The studies are not equally distributed across the categories: Most focus on causes and associated factors. Only a very small number of articles deal with psychological and somatic symptoms of burnout and attempt to develop diagnostic criteria. We argue that just this distribution is the reason why burnout research reproduces the vagueness and ambiguity of the concept that it aims to clarify, and discuss our results in the light of the concept of medicalization.

Corrigendum to “Auditory–motor synchronization facilitates attention allocation” [NeuroImage 82 (2013) 101–106]

DOI of original article: http://dx.doi.org/10.1016/j.neuroimage.2013.05.111. ⁎ Corresponding author. Fax: +49 69 6301 7606. E-mail address: schmidt-kassow@med.uni-frankfurt.de (M. Schmidt-Kassow). Fig. 1. P300 topography for significant temporal clusters (230–326 ms, 256–456 ms) and 4 representative ROI electrodes for each condition. Unfilled circles indicate recorded electrode sites and filled circles indicate ROI electrodes. Plotted electrodes are highlighted with white asterisks. Temporal clusters are marked by rectangles (solid line = 230–326 ms, dashed line = 256–456 ms). Panel A: Sedentary condition. Panel B: Pedaling condition. PP = Pedaling periodic, PA = Pedaling aperiodic, SP = Sedentary periodic, SA = Sedentary aperiodic.

Burnout: From Work-Related Stress to a Cover-Up Diagnosis

Linda and Torsten Heinemann investigate German and American academic and popular media sources in order to analyse different conceptions of burnout in these cultures. Tracing a development that begins with Freudenberger’s introduction of the term and that ends with the present day, they show that a surge in media interest, especially in the past decade, is noticeable in Germany. In the United States, by contrast, the term remains confined to specific professions, and is not generally considered a culturally all-embracing condition. Torsten and Linda Heinemann also explore the specific nature of public discussions of burnout, and draw attention to the comparatively individualistic conception of the disease in the United States, which contrasts with what the German media present as predominantly a social crisis in the age of neoliberalism.