Biomedical subjects

Sabine Windmann

Publications and source records attributed to Sabine Windmann.

10 recordsLinked to original sources

PubMed2006

Creative thinking in adolescents with attention deficit hyperactivity disorder (ADHD).

A widened attentional focus, that is typically associated with ADHD, has been postulated to be accompanied by enhanced creative ability. However, creativity has been only limitedly examined in ADHD. Performance across several creativity measures were investigated in three groups: adolescents with ADHD, those with conduct disorder, and a healthy control sample. The ADHD group exhibited selective cognitive advantages and disadvantages by demonstrating an enhanced ability in overcoming the constraining influence of examples, but a reduced capacity to generate a functional invention during an imagery task. These findings are interpreted with reference to inhibitory control mechanisms and the contextual modulation of creative cognition.

Adolescent↗

PubMed2006

Single forebrain neurons represent interval timing and reward amount during response scheduling.

Climbing activity, the gradual increase of neural discharge rate across a delay, has been suggested to play a crucial role in interval timing. However, most previous studies demonstrated climbing activity only in conjunction with tasks that involved a passive tracking of the passage of time, but that did not necessitate to actively time an event, e.g. a motor response. To demonstrate the significance of climbing activity for action timing, we trained pigeons in a self-control task requiring either immediate responding to a key after the onset of a light cue ('rapid-response' trials), or waiting for a fixed interval after cue presentation before responding to the key ('wait' trials). The cue also indicated whether a correctly timed response would be rewarded with a large or a small reward. Single-cell recordings in the Nidopallium caudolaterale, the avian prefrontal cortex, revealed that some neurons showed climbing activity between cue onset and response. Their increase in firing rate was flatter and reached the peak later in wait compared with rapid-response trials. An error analysis confirmed that, relative to correct responses, premature responses were accompanied by steeper, and tardy responses by flatter ramps. In addition, the climbing discharge pattern was modulated by the amount of the anticipated reward, suggesting that timing is an intrinsic property of neurons encoding other task-related information. These results demonstrate the behavioural and motivational significance of climbing activity in prospective information encoding. Our study supports a recent paradigm shift in our understanding of the vertebrate brain evolution, and it provides further evidence for the similarity between the mammalian cortex and the avian pallium.

Action Potentials↗

PubMed2006

Role of the prefrontal cortex in attentional control over bistable vision.

The primary source of top-down attentional control in object perception is the prefrontal cortex. This region is involved in the maintenance of goal-related information as well as in attentional selection and set shifting. Recent approaches have emphasized the role of top-down processes during elementary visual processes as exemplified in bistable vision where perception oscillates automatically between two mutually exclusive states. The prefrontal cortex might influence this process either by maintaining the dominant pattern while protecting it against the competing representation, or by facilitating perceptual switches between the two competing representations. To address this issue, we investigated reported perceptual reversals in patients with circumscribed lesions of the prefrontal cortex and healthy control participants in three experimental conditions: hold (maintaining the dominant view), speed (inducing as many perceptual switches as possible), and neutral (no intervention). Results indicated that although the patients showed normal switching rates in the neutral condition and were able to control perceptual switches in the hold condition as much as control subjects were, they were less able to facilitate reversals specifically in the speed condition. These results suggest that the prefrontal cortex is necessary to bias the selection of visual representations in accord with current goals, but is less essential for maintaining selected information active that is continuously available in the environment. As for attentional selection, the present results suggest that the prefrontal cortex initiates perceptual reversals by withdrawing top-down support from the dominant representation without (or prior to) boosting the suppressed view.

Attention↗

PubMed2006

On framing effects in decision making: linking lateral versus medial orbitofrontal cortex activation to choice outcome processing.

Two correlates of outcome processing in the orbitofrontal cortex (OFC) have been proposed in the literature: One hypothesis suggests that the lateral/medial division relates to representation of outcome valence (negative vs. positive), and the other suggests that the medial OFC maintains steady stimulus-outcome associations, whereas the lateral OFC represents changing (unsteady) outcomes to prepare for response shifts. These two hypotheses were contrasted by comparing the original with the inverted version of the Iowa Gambling Task in an event-related functional magnetic resonance imaging experiment. Results showed (1) that (caudo) lateral OFC was indeed sensitive to the steadiness of the outcomes and not merely to outcome valence and (2) that the original and the inverted tasks, although both designed to measure sensitivity for future outcomes, were not equivalent as they enacted different behaviors and brain activation patterns. Results are interpreted in terms of Kahneman and Tversky's prospect theory suggesting that cognitions and decisions are biased differentially when probabilistic future rewards are weighed against consistent punishments relative to the opposite scenario [Kahneman, D., & Tversky, A. Choices, values, and frames. American Psychologist, 39, 341-350, 1984]. Specialized processing of unsteady rewards (involving caudolateral OFC) may have developed during evolution in support of goal-related thinking, prospective planning, and problem solving.

Adult↗

PubMed2005

Is interhemispheric communication disturbed when the two hemispheres perform on separate tasks?

The coordination of sensorimotor tasks involving both visual half-fields requires exchange of information between the brain hemispheres. So far, this interhemispheric information transfer has never been investigated under conditions where the two hemispheres receive different visual inputs and each hemisphere performs on a different task. The present study asked whether such conditions affect the transfer of information between the hemispheres, and if so, at which processing stage. We addressed these issues by pairing a face comparison task with a visual discrimination task (I-task) designed to interfere with the interhemispheric information transfer required for face comparison. One version of the I-task (experiment 1) required discrimination of the faces of John Lennon and Yoko Ono; the other version (experiment 2) required discrimination between the names 'JOHN' and 'YOKO'. Thus, the two I-task versions overlapped at early visual processing stages where visual feature analysis is carried out, but differed at later processing stages where words or faces are represented as objects. We found that both I-task versions disrupted the interhemispheric information transfer for the face comparison task. This indicates that when both hemispheres are occupied by separate tasks, interhemispheric communication is less efficient. In addition, our results suggest that the hemispheres exchange sensory information already at a rather early visual processing stage. Hence, visual feature analysis in one hemisphere is probably informed about feature analysis in the other hemisphere and may also be modulated by it.

Adult↗

PubMed2005

Single units in the pigeon brain integrate reward amount and time-to-reward in an impulsive choice task.

BACKGROUND: Animals prefer small over large rewards when the delays preceding large rewards exceed an individual tolerance limit. Such impulsive choice behavior occurs even in situations in which alternative strategies would yield more optimal outcomes. Behavioral research has shown that an animal's choice is guided by the alternative rewards' subjective values, which are a function of reward amount and time-to-reward. Despite increasing knowledge about the pharmacology and anatomy underlying impulsivity, it is still unknown how the brain combines reward amount and time-to-reward information to represent subjective reward value. RESULTS: We trained pigeons to choose between small, immediate rewards and large rewards delivered after gradually increasing delays. Single-cell recordings in the avian Nidopallium caudolaterale, the presumed functional analog of the mammalian prefrontal cortex, revealed that neural delay activation decreased with increasing delay length but also covaried with the expected reward amount. This integrated neural response was modulated by reward amount and delay, as predicted by a hyperbolical equation, of subjective reward value derived from behavioral studies. Furthermore, the neural activation pattern reflected the current reward preference and the time point of the shift from large to small rewards. CONCLUSIONS: The reported activity was modulated by the temporal devaluation of the anticipated reward in addition to reward amount. Our findings contribute to the understanding of neuropathologies such as drug addiction, pathological gambling, frontal lobe syndrome, and attention-deficit disorders, which are characterized by inappropriate temporal discounting and increased impulsiveness.

Animals↗

PubMed2005

Conceptual expansion and creative imagery as a function of psychoticism.

The ability to be creative is often considered a unique characteristic of conscious beings and many efforts have been directed at demonstrating a relationship between creativity and the personality construct of psychoticism. The present study sought to investigate this link explicitly by focusing on discrete facets of creative cognition, namely the originality/novelty dimension and the practicality/usefulness dimension. Based on Eysenck's conceptualisation of psychoticism as being characterised by an overinclusive cognitive style, it was expected that higher levels of psychoticism would accompany a greater degree of conceptual expansion and elevated levels of originality in creative imagery, but would be unrelated to the practicality/usefulness of an idea. These hypotheses were confirmed in 80 healthy participants who were contrasted based on their EPQ psychoticism scale scores. Our findings suggest that the link between psychoticism and creativity is based on associative thinking and broader but weak top-down activation patterns rather than on goal-related thinking.

Adult↗

PubMed2002

Dissociating prelexical and postlexical processing of affective information in the two hemispheres: effects of the stimulus presentation format.

Using a lexical decision task, the authors investigated whether brain asymmetries in the detection of emotionally negative semantic associations arise only at a perceptually discriminative stage at which lexical analysis is accurate or can already be found at crude and incomplete levels of perceptual representation at which word-nonword discrimination is based solely on guessing. Emotionally negative and neutral items were presented near perceptual threshold in the left and right visual hemifields. Word-nonword discrimination performance as well as the bias to classify a stimulus as a "word" (whether or not it actually is a word) were assessed for a normal, horizontal stimulus presentation format (Experiment 1) and for an unusual, vertical presentation format (Experiment 2). Results show that while the two hemispheres are equally able to detect affective semantic associations at a prelexical processing stage (both experiments), the right hemisphere is superior at a postlexical, perceptually discriminative stage (Experiment 2). Moreover, the findings suggest that only an unusual, nonoverlearned stimulus presentation format allows adequate assessment of the right hemisphere's lexical-semantic skills.

Adult↗

PubMed2002

Cognitive and neural mechanisms of decision biases in recognition memory.

In recognition memory tasks, stimuli can be classified as "old" either on the basis of accurate memory or a bias to respond "old", yet bias has received little attention in the cognitive neuroscience literature. Here we examined the pattern and timing of bias-related effects in event-related brain potentials (ERPs) to determine whether the bias is linked more to memory retrieval or to response verification processes. Participants were divided into a High Bias and a Low Bias group according to their bias to respond "old". These groups did not differ in recognition accuracy or in the ERP pattern to items that actually were old versus new (Objective Old/New Effect). However, when the old/new distinction was based on each subject's perspective, i.e. when items judged "old" were compared with those judged "new" (Subjective Old/New Effect), significant group differences were observed over prefrontal sites with a timing (300-500 ms poststimulus) more consistent with bias acting early on memory retrieval processes than on post-retrieval response verification processes. In the standard old/new effect (Hits vs Correct Rejections), these group differences were intermediate to those for the Objective and the Subjective comparisons, indicating that such comparisons are confounded by response bias. We propose that these biases are top-down controlled processes mediated by prefrontal cortex areas.

Adolescent↗

PubMed2002

Electrophysiological evidence reveals affective evaluation deficits early in stimulus processing in patients with panic disorder.

Cognitive and neurobiological accounts of clinical anxiety and depression were examined via event-related brain potentials (ERPs) recorded from patients with panic disorder and healthy controls as they performed an old/new recognition memory task with emotionally negative and neutral words. The emotive connotation of words systematically influenced control subjects' - but not patients' - ERP effects at prefrontal sites in a latency range (to approximately 300-500 ms) generally assumed to reflect greater contribution of automatic than controlled memory processes. This provides evidence for dysfunctional inhibitory modulation of affective information processing in panic disorder. The ERP effects after 700 ms, however, suggest that some patients may adopt conscious strategies to minimize the impact of these early processing abnormalities on overt behaviors.

Adolescent↗