Showing papers by "Heleen A. Slagter published in 2013"
TL;DR: Rec retrieval was not enhanced after alternating left-right auditory stimulation compared to simultaneous bilateral auditory stimulation, and the possibility that alternating bilateral activation of the left and right hemisphere exerts its effects on memory by increasing the functional connectivity between the two hemispheres was discussed.
56 citations
TL;DR: It is found that individual differences in the direction and magnitude of the orienting bias were strongly associated with the pattern of asymmetric binding of dopamine D2 receptors in the striatum, as well as clusters in the frontal and temporal cortex.
Abstract: Pseudoneglect is traditionally viewed as reflecting right hemisphere specialization for processing spatial information, resulting in orienting toward the contralateral, left, hemispace. Recent evidence suggests that healthy individuals differ from each other in both direction and magnitude of orienting bias, and moreover, the bias displayed by a person is consistent across time, suggesting that it may represent a trait of the individual. Animal studies reveal consistent orienting bias within an individual, which reflects asymmetry in dopaminergic brain systems. We measured basal D2-like receptor binding using positron emission tomography and the high-affinity ligand [F-18]fallypride, to test the hypothesis that asymmetry in dopaminergic neurotransmission in healthy humans modulates the orienting bias in humans. As predicted, we found that individual differences in the direction and magnitude of the orienting bias were strongly associated with the pattern of asymmetric binding of dopamine (DA) D2 receptors in the striatum, as well as clusters in the frontal and temporal cortex. These findings show for the first time that orienting bias reflects individual differences in the lateralization of DA systems in the healthy human brain.
51 citations
TL;DR: It is indicated that a failure to inhibit distracting information impairs AB recovery, possibly by interfering with target encoding in working memory - but does not affect AB magnitude.
Abstract: Background: The attentional blink (AB) refers to an impairment in detecting the second of two target stimuli presented in close succession in a rapid stream of distractors. Recent studies indicate that the AB results, in part, from distractor suppression mechanisms, that may be mediated by striatal dopamine. Yet, it is currently unclear how distractor suppression ability may contribute to the AB. Here, we examined whether distractor suppression ability is predictive of an individual’s AB depth and/or recovery. In addition, we investigated the relationship between individual spontaneous eye blink rate (sEBR), a marker of striatal dopaminergic functioning, and AB performance. Methodology/Principal findings: Subjects were presented with rapid streams of letters containing white distractors, a red T1 and a green T2. T2 was presented either at Lag2, Lag4 or Lag10, and preceded by a distractor that shared the same identity as T2 (T2 primed) or not (T2 not primed). Replicating previous work [1], we found that slow AB recovery (poor T2 performance in Lag4 vs. Lag10) was associated with a failure to inhibit distractors, as indexed by greater positive priming. However, no relationship was observed between a subject’s ability to suppress distractors and AB depth (Lag10 vs. Lag2). Moreover, no relationship between sEBR and AB performance was observed. Results/Significance: These results indicate that a failure to inhibit distracting information impairs AB recovery, possibly by interfering with target encoding in working memory - but does not affect AB magnitude. The absence of a relationship between individual sEBR and AB performance may be explained by task specifics.
16 citations
TL;DR: It is shown that estimated strength of white-matter connections between the first relay station in the auditory processing stream, the cochlear nucleus, the auditory thalamus, and primary auditory cortex predicted one’s ability to combine auditory and visual information in a visual search task.
Abstract: Oftentimes, we perceive our environment by integrating information across multiple senses. Recent studies suggest that such integration occurs at much earlier processing stages than once thought possible, including in thalamic nuclei and putatively unisensory cortical brain regions. Here, we used diffusion tensor imaging (DTI) and an audiovisual integration task to test the hypothesis that anatomical connections between sensory-related subcortical structures and sensory cortical areas govern multisensory processing in humans. Twenty-five subjects (mean age 22 years, 22 females) participated in the study. In line with our hypothesis, we show that estimated strength of white-matter connections between the first relay station in the auditory processing stream (the cochlear nucleus), the auditory thalamus, and primary auditory cortex predicted one’s ability to combine auditory and visual information in a visual search task. This finding supports a growing body of work that indicates that subcortical sensory pathways do not only feed forward unisensory information to the cortex, and suggests that anatomical brain connectivity contributes to multisensory processing ability in humans.
6 citations
01 Oct 2013
TL;DR: Whether attention can be improved with electrical stimulation of the brain, in the form of transcranial Direct Current Stimulation (tDCS), and the opposite effect: decreases in attention, when attention has to be sustained for a long time are investigated.
Abstract: Attention allows us to focus on what is relevant and to ignore what is not. While we call upon attention at every waking moment, it is not static: we cannot sustain attention indefinitely, and often fall prey to distractions. This PhD thesis is a study of the short-term neuroplasticity of attentional processes: how susceptible is attention to change, and what processes in the brain (neuro-) give rise to changes in attention (-plasticity)? In Chapters 2–5, I examined whether attention can be improved with electrical stimulation of the brain, in the form of transcranial Direct Current Stimulation (tDCS). Previous studies that attempted to use tDCS to enhance attention have yielded promising, but inconsistent results (reviewed in Chapter 2). My attempt to enhance spatial attention with tDCS (Chapter 3) was unsuccessful, as stimulation of the frontal eye fields did not lead to changes in eye movements. Applying tDCS over the dorsolateral prefrontal cortex also did not enhance temporal attention (Chapters 4 and 5), as participants’ performance on an attentional blink task remained unchanged. In Chapter 6, I investigated the opposite effect: decreases in attention, when attention has to be sustained for a long time. Using EEG, I tracked whether similar decreases occurred in different attention-related signals in the brain. tDCS may one day be used to counteract these declines, or to relieve other deficits in attention. However, barring a deeper understanding of the technique and more large-scale studies of its efficacy, such practical applications of tDCS are not yet feasible.
5 citations