Biomedical subjects

Tobias Flaisch

Publications and source records attributed to Tobias Flaisch.

6 recordsLinked to original sources

PubMed2006

Brain regions essential for improved lexical access in an aged aphasic patient: a case report.

BACKGROUND: The relationship between functional recovery after brain injury and concomitant neuroplastic changes is emphasized in recent research. In the present study we aimed to delineate brain regions essential for language performance in aphasia using functional magnetic resonance imaging and acquisition in a temporal sparse sampling procedure, which allows monitoring of overt verbal responses during scanning. CASE PRESENTATION: An 80-year old patient with chronic aphasia (2 years post-onset) was investigated before and after intensive language training using an overt picture naming task. Differential brain activation in the right inferior frontal gyrus for correct word retrieval and errors was found. Improved language performance following therapy was mirrored by increased fronto-thalamic activation while stability in more general measures of attention/concentration and working memory was assured. Three healthy age-matched control subjects did not show behavioral changes or increased activation when tested repeatedly within the same 2-week time interval. CONCLUSION: The results bear significance in that the changes in brain activation reported can unequivocally be attributed to the short-term training program and a language domain-specific plasticity process. Moreover, it further challenges the claim of a limited recovery potential in chronic aphasia, even at very old age. Delineation of brain regions essential for performance on a single case basis might have major implications for treatment using transcranial magnetic stimulation.

Aged↗

PubMed2006

Emotion and attention: event-related brain potential studies.

Emotional pictures guide selective visual attention. A series of event-related brain potential (ERP) studies is reviewed demonstrating the consistent and robust modulation of specific ERP components by emotional images. Specifically, pictures depicting natural pleasant and unpleasant scenes are associated with an increased early posterior negativity, late positive potential, and sustained positive slow wave compared with neutral contents. These modulations are considered to index different stages of stimulus processing including perceptual encoding, stimulus representation in working memory, and elaborate stimulus evaluation. Furthermore, the review includes a discussion of studies exploring the interaction of motivated attention with passive and active forms of attentional control. Recent research is reviewed exploring the selective processing of emotional cues as a function of stimulus novelty, emotional prime pictures, learned stimulus significance, and in the context of explicit attention tasks. It is concluded that ERP measures are useful to assess the emotion-attention interface at the level of distinct processing stages. Results are discussed within the context of two-stage models of stimulus perception brought out by studies of attention, orienting, and learning.

Attention↗

PubMed2006

The neural basis of narrative imagery: emotion and action.

It has been proposed that narrative emotional imagery activates an associative network of stimulus, semantic, and response (procedural) information. In previous research, predicted response components have been demonstrated through psychophysiological methods in peripheral nervous system. Here we investigate central nervous system concomitants of pleasant, neutral, and unpleasant narrative imagery with functional magnetic resonance imaging. Subjects were presented with brief narrative scripts over headphones, and then imagined themselves engaged in the described events. During script perception, auditory association cortex showed enhanced activation during affectively arousing (pleasant and unpleasant), relative to neutral imagery. Structures involved in language processing (left middle frontal gyrus) and spatial navigation (retrosplenium) were also active during script presentation. At the onset of narrative imagery, supplementary motor area, lateral cerebellum, and left inferior frontal gyrus were initiated, showing enhanced signal change during affectively arousing (pleasant and unpleasant), relative to neutral scripts. These data are consistent with a bioinformational model of emotion that considers response mobilization as the measurable output of narrative imagery.

Acoustic Stimulation↗

PubMed2006

Neuroimaging methods in affective neuroscience: selected methodological issues.

A current goal of affective neuroscience is to reveal the relationship between emotion and dynamic brain activity in specific neural circuits. In humans, noninvasive neuroimaging measures are of primary interest in this endeavor. However, methodological issues, unique to each neuroimaging method, have important implications for the design of studies, interpretation of findings, and comparison across studies. With regard to event-related brain potentials, we discuss the need for dense sensor arrays to achieve reference-independent characterization of field potentials and improved estimate of cortical brain sources. Furthermore, limitations and caveats regarding sparse sensor sampling are discussed. With regard to event-related magnetic field (ERF) recordings, we outline a method to achieve magnetoencephalography (MEG) sensor standardization, which improves effects' sizes in typical neuroscientific investigations, avoids the finding of ghost effects, and facilitates comparison of MEG waveforms across studies. Focusing on functional magnetic resonance imaging (fMRI), we question the unjustified application of proportional global signal scaling in emotion research, which can greatly distort statistical findings in key structures implicated in emotional processing and possibly contributing to conflicting results in affective neuroscience fMRI studies, in particular with respect to limbic and paralimbic structures. Finally, a distributed EEG/MEG source analysis with statistical parametric mapping is outlined providing a common software platform for hemodynamic and electromagnetic neuroimaging measures. Taken together, to achieve consistent and replicable patterns of the relationship between emotion and neuroimaging measures, methodological aspects associated with the various neuroimaging techniques may be of similar importance as the definition of emotional cues and task context used to study emotion.

Brain↗

PubMed2004

Affective picture perception: gender differences in visual cortex?

Activity in extrastriate visual cortex is greater when people view emotional relative to neutral pictures. Prior brain imaging and psychophysiological work has further suggested a bias for men to react more strongly to pleasant pictures, and for women to react more strongly to unpleasant pictures. Here we investigated visual cortical activity using fMRI in 28 men and women during picture viewing. Men and women showed reliably greater visual cortical reactivity during both pleasant and unpleasant pictures, relative to neutral, consistent with the view that the motivational relevance of visual stimuli directs attention and enhances elaborative perceptual processing. However, men did show greater extrastriate activity than women specifically during erotic picture perception, possibly reflecting a gender-specific visual mechanism for sexual selection.

Adolescent↗

PubMed2003

Corticolimbic mechanisms in emotional decisions.

Midline frontolimbic networks are engaged in monitoring simple actions. They may also provide evaluative control for more complex decisions. Subjects read a trait-descriptive word and responded either "yes" or "no" within 1,500 ms whether it was self-descriptive. By 300 ms, an electrophysiological discrimination between good and bad words was seen over centromedial regions of the frontal lobe for both friend and self-decisions. By 350 ms, an interaction effect between evaluation and endorsement appeared, and by 500 ms, activity specific to self-evaluation was seen in both anterior and posterior midline sites. An evaluative decision thus begins by recruiting motivational and semantic influences within limbic networks, and these influences appear to shape the development of the decision within multiple neocortical regions.

Adult↗