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Author: Eva Friedel (20)


Jan
2018

The influence of Pavlovian conditioned stimuli on ongoing behavior may contribute to explaining how alcohol cues stimulate drug seeking and intake. Using a Pavlovian-instrumental transfer task, we investigated the effects of alcohol-related cues on approach behavior (i.e.

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Dec
1969

Advances in neurocomputational modeling suggest that valuation systems for goal-directed (deliberative) on one side, and habitual (automatic) decision-making on the other side may rely on distinct computational strategies for reinforcement learning, namely model-free vs. model-based learning. As a key theoretical difference, the model-based system strongly demands cognitive functions to plan actions prospectively based on an internal cognitive model of the environment, whereas valuation in the model-free system relies on rather simple learning rules from operant conditioning to retrospectively associate actions with their outcomes and is thus cognitively less demanding.

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Jul
2017

Appetitive Pavlovian conditioning plays a crucial role in the pathogenesis of drug addiction and conditioned reward cues can trigger craving and relapse even after long phases of abstinence. Promising preclinical work showed that the NMDA-receptor partial agonist D-cycloserine (DCS) facilitates Pavlovian extinction learning of fear and drug cues. Furthermore, DCS-augmented exposure therapy seems to be beneficial in various anxiety disorders, while the supposed working mechanism of DCS during human appetitive or aversive extinction learning is still not confirmed.

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Dec
1969

Studying psychiatric disorders across nosological boundaries aims at a better understanding of mental disorders by identifying comprehensive signatures of core symptoms. Here, we studied neurobiological correlates of emotion processing in several major psychiatric disorders. We assessed differences between diagnostic groups, and investigated whether there is a psychopathological correlate of emotion processing that transcends disorder categories.

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May
2016

In detoxified alcohol-dependent patients, alcohol-related stimuli can promote relapse. However, to date, the mechanisms by which contextual stimuli promote relapse have not been elucidated in detail. One hypothesis is that such contextual stimuli directly stimulate the motivation to drink via associated brain regions like the ventral striatum and thus promote alcohol seeking, intake and relapse.

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Dec
1969

Pavlovian processes are thought to play an important role in the development, maintenance and relapse of alcohol dependence, possibly by influencing and usurping ongoing thought and behavior. The influence of pavlovian stimuli on ongoing behavior is paradigmatically measured by pavlovian-to-instrumental transfer (PIT) tasks. These involve multiple stages and are complex.

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Dec
1969

Alcohol dependence is one of the leading contributors to the burden of disease in the world. A range of genetic and environmental risk factors has been identified to date, and preclinical and clinical studies including imaging studies have identified neuronal networks involved in the development of alcohol dependence.
We review genetic and environmental risk factors for the development of alcohol addiction as well as structural and neuronal changes, including their transmitter systems, due to regular alcohol intake.

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Feb
2015

Fluid intelligence (fluid IQ), defined as the capacity for rapid problem solving and behavioral adaptation, is known to be modulated by learning and experience. Both stressful life events (SLES) and neural correlates of learning [specifically, a key mediator of adaptive learning in the brain, namely the ventral striatal representation of prediction errors (PE)] have been shown to be associated with individual differences in fluid IQ. Here, we examine the interaction between adaptive learning signals (using a well-characterized probabilistic reversal learning task in combination with fMRI) and SLES on fluid IQ measures.

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Dec
1969

In experimental psychology different experiments have been developed to assess goal-directed as compared to habitual control over instrumental decisions. Similar to animal studies selective devaluation procedures have been used. More recently sequential decision-making tasks have been designed to assess the degree of goal-directed vs.

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Oct
2013

Dysfunctional emotion processing in patients suffering from schizophrenia is a prominent clinical feature of great importance for social functioning and subjective well-being. The neurobiological underpinnings are still poorly understood. Here we investigated a large sample of schizophrenia patients and matched healthy controls with an event-related fMRI task during emotion processing using emotional pictures from the International Affective Picture System (IAPS).

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Dec
1969

Early dysfunction of the brain reward system in schizophrenia might be already recognized in the prodromal phase of this illness. We used functional magnetic resonance imaging to assess the blood oxygen level-dependent response in the ventral striatum (VS) of subjects with ultra-high risk for psychosis during the presentation of reward-indicating and loss-indicating stimuli.
Thirteen prodromal patients (mean age: 25.

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Nov
2012

Major Depressive Disorder (MDD) is associated with impaired processing and regulation of emotions. A vast body of research has elucidated the altered neural processes that occur in response to emotional stimuli, while little is known about anticipatory processes. Here we used functional magnetic resonance imaging (fMRI) to investigate neural activation during the presentation and anticipation of negative stimuli.

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Apr
2011

Hard-wired, Pavlovian, responses elicited by predictions of rewards and punishments exert significant benevolent and malevolent influences over instrumentally-appropriate actions. These influences come in two main groups, defined along anatomical, pharmacological, behavioural and functional lines. Investigations of the influences have so far concentrated on the groups as a whole; here we take the critical step of looking inside each group, using a detailed reinforcement learning model to distinguish effects to do with value, specific actions, and general activation or inhibition.

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Aug
2011

Neural correlates of emotional dysregulation in attention-deficit/hyperactivity disorder (ADHD) and persisting influence of Methylphenidate (MPH) still remain insufficiently understood. Decreased activation in the subgenual cingulate and the ventral striatum were found during the perception of positive and negative affective pictures in drug-naïve males with ADHD during childhood (n=10). Males with ADHD during childhood treated with MPH (n=10) did not show any significant differences compared to healthy controls (n=10).

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May
2010

Deficits in working memory (WM) are a core symptom of schizophrenia patients and have been linked to dysfunctional prefrontal activation, which might be caused by a mesocortical hypodopaminergic state. Aripiprazole--a partial dopamine antagonist--is a novel antipsychotic, which increases frontal dopamine concentrations in preclinical studies. However, little is known about specific medication effects on the modulation of frontal activation during WM performance.

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Aug
2009

In major depression, prefrontal regulation of limbic brain areas may be a key mechanism that is impaired during the processing of affective information. This prefrontal-limbic interaction has been shown to be modulated by serotonin (5-HTT) genotype, indicating a higher risk for major depressive disorder (MDD) with increasing number of 5-HTT low-expression alleles.
Functional magnetic resonance imaging was used to assess neural response to uncued unpleasant affective pictures in 21 unmedicated patients with MDD compared to 21 matched healthy controls, taking into account genetic influences of the 5-HTT (SCL6A4) high- and low-expression genotype.

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Jan
2008

Effort has repeatedly been shown to have a pervasive effect on performance in psychological tests. The current study evaluates to what degree performance on various psychological tests is affected by lack of effort as compared with brain injury. Psychological and medical data from a sample of 233 patients referred from Workers' Compensation Boards or from claimants in personal injury litigation were retrospectively analyzed.

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Sep
2006

Recent neuroimaging studies have revealed that tactile perceptual learning can lead to substantial reorganizational changes of the brain. We report here for the first time that combining high-frequency (15 Hz) repetitive transcranial magnetic stimulation (rTMS) over the primary somatosensory cortex (SI) with tactile discrimination training is capable of facilitating operant perceptual learning. Most notably, increasing the excitability of SI by 15-Hz rTMS improved perceptual learning in spatial, but not in temporal, discrimination tasks.

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