Error-related brain potentials elicited by vocal errors.

Error-related negativity (ERN) is observed immediately after an error in choice reaction time tasks performed by hand response. We examined whether the ERN occurs in relation to slips of vocalization in the Stroop color word task. In one condition, the subject's vocal responses were masked by continuous pink noise in order to prevent vocalization-related cortical potentials from contaminating the ERN time window. This masking procedure was successful in inhibiting the vocalization-related cortical potential. More importantly, vocalization errors elicited a frontocentral negative-going deflection followed by a positive component immediately after the error response regardless of the masking condition. The present results suggest that the error detection mechanism may also elicit an ERN-like component in response to vocal slips.     

Reward positivity elicited by predictive cues

A recent theory holds that a component of the human event-related brain potential called the reward positivity reflects a reward prediction error signal. We investigated this idea in gambling-like task in which, on each trial, a visual stimulus predicted a subsequent rewarding or nonrewarding outcome with 80% probability. Consistent with earlier results, we found that the reward positivity was larger to unexpected than to expected outcomes. In addition, we found that the predictive cues also elicited a reward positivity, as proposed by the theory. These results indicate that the reward positivity reflects the initial assessment of whether a trial will end in success or failure and the reappraisal of that information once the outcome actually occurs.     

Paraquat elicited neurobehavioral syndrome caused by dopaminergic neuron loss

The herbicide paraquat, bearing structural similarity to the known dopaminergic neurotoxicant MPTP, has been suggested as a potential etiologic factor in Parkinson's disease. Consideration of paraquat as a candidate neurotoxicant requires demonstration that systemic delivery produces substantia nigra dopaminergic neuron loss and the attendant neurobehavioral syndrome reflecting depletion of dopamine terminals within the striatum. To address these issues paraquat was administered systemically into adult C57 bl/6 mice, ambulatory behavior monitored, substantia nigra dopamine neuron number and striatal dopamine terminal density quantified. The data indicate that paraquat like MPTP elicits a dose-dependent decrease in substantia nigra dopaminergic neurons assessed by a Fluoro-gold prelabeling method, a decline in striatal dopamine nerve terminal density assessed by measurement of tyrosine hydroxylase immunoreactivity; and neurobehavioral syndrome characterized by reduced ambulatory activity. Taken together, these data suggest that systemically absorbed paraquat crosses the blood-brain barrier to cause destruction of dopamine neurons in the substantia nigra, consequent reduction of dopaminergic innervation of the striatum and a neurobehavioral syndrome similar to the well characterized and bona fide dopaminergic toxin MPTP.     

Differential neural activity during search of specific and general autobiographical memories elicited by musical cues

Previous neuroimaging studies that have examined autobiographical memory specificity have utilized retrieval cues associated with prior searches of the event, potentially changing the retrieval processes being investigated. In the current study, musical cues were used to naturally elicit memories from multiple levels of specificity (i.e., lifetime period, general event, and event-specific). Sixteen young adults participated in a neuroimaging study in which they retrieved autobiographical memories associated with musical cues. These musical cues led to the retrieval of highly emotional memories that had low levels of prior retrieval. Retrieval of all autobiographical memory levels was associated with activity in regions in the autobiographical memory network, specifically the ventromedial prefrontal cortex, posterior cingulate, and right medial temporal lobe. Owing to the use of music, memories from varying levels of specificity were retrieved, allowing for comparison of event memory and abstract personal knowledge, as well as comparison of specific and general event memory. Dorsolateral and dorsomedial prefrontal regions were engaged during event retrieval relative to personal knowledge retrieval, and retrieval of specific event memories was associated with increased activity in the bilateral medial temporal lobe and dorsomedial prefrontal cortex relative to retrieval of general event memories. These results suggest that the initial search processes for memories of different specificity levels preferentially engage different components of the autobiographical memory network. The potential underlying causes of these neural differences are discussed.     

Activation in mesolimbic and visuospatial neural circuits elicited by smoking cues: evidence from functional magnetic resonance imaging

OBJECTIVE: The authors sought to increase understanding of the brain mechanisms involved in cigarette addiction by identifying neural substrates modulated by visual smoking cues in nicotine-deprived smokers. METHOD: Event-related functional magnetic resonance imaging (fMRI) was used to detect brain activation after exposure to smoking-related images in a group of nicotine-deprived smokers and a nonsmoking comparison group. Subjects viewed a pseudo-random sequence of smoking images, neutral nonsmoking images, and rare targets (photographs of animals). Subjects pressed a button whenever a rare target appeared. RESULTS: In smokers, the fMRI signal was greater after exposure to smoking-related images than after exposure to neutral images in mesolimbic dopamine reward circuits known to be activated by addictive drugs (right posterior amygdala, posterior hippocampus, ventral tegmental area, and medial thalamus) as well as in areas related to visuospatial attention (bilateral prefrontal and parietal cortex and right fusiform gyrus). In nonsmokers, no significant differences in fMRI signal following exposure to smoking-related and neutral images were detected. In most regions studied, both subject groups showed greater activation following presentation of rare target images than after exposure to neutral images. CONCLUSIONS: In nicotine-deprived smokers, both reward and attention circuits were activated by exposure to smoking-related images. Smoking cues are processed like rare targets in that they activate attentional regions. These cues are also processed like addictive drugs in that they activate mesolimbic reward regions.     

Low dose of heroin inhibits drug-seeking elicited by cues after prolonged withdrawal from heroin self-administration in rats

Environmental stimuli and conditioned cues associated with heroin can induce drug-seeking behavior, but how heroin lapse interacts with cues is unclear. Rats were trained to nose-poke for i.v. heroin for 14 days and then tested for heroin seeking after withdrawal from heroin self-administration. Heroin seeking induced by cues persisted over several weeks after withdrawal, and the responding was not easily extinguished after 4 weeks withdrawal. A single injection of heroin (250 micro g/kg) enhanced the responding at early stage of withdrawal, but a low dose of heroin (50, 250 micro g/kg) suppressed the responding induced by contextual or conditioned cues at 4 weeks of withdrawal. The results suggest that prolonged withdrawal may increase the risk of relapse to heroin seeking.     

Altered monetary loss processing and reinforcement-based learning in individuals with obesity

Individuals with obesity are often characterized by alterations in reward processing. This may affect how new information is used to update stimulus values during reinforcement-based learning. Here, we investigated obesity-related changes in non-food reinforcement processing, their impact on learning performance as well as the neural underpinnings of reinforcement-based learning in obesity. Nineteen individuals with obesity (BMI?>?=?30 kg/m², 10 female) and 23 lean control participants (BMI 18.5–24.9 kg/m², 11 female) performed a probabilistic learning task during functional magnetic resonance imaging (fMRI), in which they learned to choose between advantageous and disadvantageous choice options in separate monetary gain, loss, and neutral conditions. During learning individuals with obesity made a significantly lower number of correct choices and accumulated a significantly lower overall monetary outcome than lean control participants. FMRI analyses revealed aberrant medial prefrontal cortex responses to monetary losses in individuals with obesity. There were no significant group differences in the regional representation of prediction errors. However, we found evidence for increased functional connectivity between the ventral striatum and insula in individuals with obesity. The present results suggest that obesity is associated with aberrant value representations for monetary losses, alterations in functional connectivity during the processing of learning outcomes, as well as a decresased reinforcement-based learning performance. This may affect how new information is incorporated to adjust dysfunctional behavior and could be a factor contributing to the maintenance of dysfunctional eating behavior in obesity.     

Attention allocation and social worries predict interpretations of peer-related social cues in adolescents

Adolescence is a sensitive period for increases in normative but also debilitating social fears and worries. As the interpretation of interpersonal cues is pertinent to social anxiety, investigating mechanisms that may underlie biases in social cue appraisal is important.Fifty-one adolescents from the community aged 14–19 were presented with self- and other-relevant naturalistic social scenes for 5 s and then required to rate either a negative or a positive interpretation of the scene. Eye-tracking data were collected during the free viewing period to index attentional deployment. Individual differences in social worries were measured via self-report.Social anxiety levels significantly predicted biases in interpretation ratings across scenes. Additionally, cumulative attentional deployment to peer cues also predicted these interpretation biases: participants who spent more time on facial displays perceived more threat, i.e. endorsed more negative and less positive interpretations. Self-relevant scenes yielded greater tendencies to draw negative interpretations. Finally, older adolescents also selected more benign interpretations.Social anxiety is associated with a bias in interpreting social cues; a cognitive bias that is also influenced by attentional deployment. This study contributes to our understanding of the possible attention mechanisms that shape cognitions relevant to social anxiety in this at-risk age group.     

Perceiving monetary loss as due to inequity reduces behavioral and cortical responses to pain

Studies indicate that physical and social pain may share some mechanisms and neural correlates. Nothing is known, however, on whether the neural activity in the nociceptive system, as indexed by laser‐evoked potentials (LEPs), is modified when suffering the consequences of a conspecific violating social norms. To explore this issue, we created an interaction scenario where participants could gain money by performing a time‐estimation task. On each win‐trial, another player connected online could arbitrarily decide to keep the participant's pay‐off for him‐ or herself. Thus, participants knew that monetary loss could occur because of their own failure in performing the task or because of the inequitable behavior of another individual. Moreover, participants were asked to play for themselves or on behalf of a third party. In reality, the win/loss events were entirely decided by an ad hoc programmed computer. At the end of the interaction, participants reported if they believed the game‐playing interaction was real. Results showed that the loss due to the opponent's inequitable behavior brought about a reduction both in pain intensity self‐reports and in the amplitude of LEPs' components (i.e. N2, N2/P2, P2a, P2b). Importantly, both the behavioral and neurophysiological effects were found in the participants who believed their deserved payoff was stolen by their opponent. Furthermore, reduction of vertex components was present only when the inequitable behavior was directed toward the self. These results suggest that, far from being a private experience, pain perception might be modulated by the social saliency of interpersonal interactions.     

Analgesia elicited by prefrontal stimulation

Bipolar stimulating electrodes were placed into the medial prefrontal cortex (PFC) or control sites (occipital or cerebellar cortices) in adult male rats. Subsequently, it was determined that PFC stimulation resulted in a significant elevation of nociceptive response latencies, as tested using hot plate and tail flick techniques. Stimulation in control sites did not produce an increase in these response latencies. Rats receiving PFC stimulation were able to respond normally to various innocuous stimuli. Furthermore, seizures were not observed in these rats. These facts indicated that PFC stimulation did not disorient the animals nor inhibit their voluntary motor activity. The results of this study seem to indicate that the PFC is a site from which stimulus-produced analgesia may be elicited.     

Brain signatures of monetary loss and gain: outcome-related potentials in a single outcome gambling task

This study evaluates the event-related potential (ERP) components in a single outcome gambling task that involved monetary losses and gains. The participants were 50 healthy young volunteers (25 males and 25 females). The gambling task involved valence (loss and gain) and amount (50 cent and 10 cent) as outcomes. The outcome-related negativity (ORN/N2) and outcome-related positivity (ORP/P3) were analyzed and compared across conditions and gender. Monetary gain (compared to loss) and higher amount (50 cent compared to 10 cent) produced higher amplitudes and shorter latencies in both ORN and ORP components. Difference wave plots showed that earlier processing (200-400 ms) is dominated by the valence (loss/gain) while later processing (after 400 ms) is marked by the amount (50 cent/10 cent). Functional mapping using Low Resolution Electromagnetic Tomography (LORETA) indicated that the ORN separated the loss against gain in both genders, while the ORP activity distinguished the 50 cent against 10 cent in males. This study further strengthens the view that separate brain processes/circuitry may mediate loss and gain. Although there were no gender differences in behavioral and impulsivity scores, ORN and ORP measures for different task conditions had significant correlations with behavioral scores. This gambling paradigm may potentially offer valuable indicators to study outcome processing and impulsivity in normals as well as in clinical populations.     

Demographic, criminogenic, and psychiatric factors that predict competency restoration

Previous research has investigated the characteristics of competent and incompetent defendants and restorable and nonrestorable defendants. However, less is known about the influence of current treatment variables and other systemic factors on restorability. In the present study, we sought to examine the impact of demographic, criminogenic, historical clinical, and current treatment variables on the restorability and length of stay (LOS) of incompetent defendants. We reviewed the records of 71 male patients who had been court ordered for competency restoration and subsequently discharged from a maximum-security forensic hospital. Results indicated that nonrestorable patients had more prior hospitalizations, incarcerations, and episodes of incompetence, had lower level charges, were diagnosed with a psychotic and cognitive disorder, were prescribed more medications, and had lower global assessment of functioning (GAF) scores. Nonrestorable patients were hospitalized nearly twice as long as those eventually found competent, and patients with lower IQs and lower GAFs and who spent more days on special observations had longer LOS.     

Evidence that health attributions and symptom severity predict insight in schizophrenia

Although a relationship between insight and symptomatology in schizophrenia has been repeatedly demonstrated, the influence of psychological variables such as coping mechanisms and attributional style is less clear. We evaluated health attributions, subjective resources for coping, symptomatology, general cognitive functioning, and insight among 38 consecutive admissions with DSM-III-R schizophrenia from a geographically defined catchment area. Health attributions accounted for a significant amount of insight even after symptom severity was accounted for and together predicted 32% of variation in insight scores. This study emphasizes the multifactorial nature of insight and the importance of psychological variables in addition to symptomatology.     

Effects of age and age-related hearing loss on the neural representation of speech cues.

OBJECTIVE: To examine the effects of aging and age-related hearing loss on the perception and neural representation of a time-varying speech cue. METHODS: P1, N1 and P2 cortical responses were recorded from younger and older normal-hearing adults, as well as older adults with age-related hearing loss. Synthetic speech tokens representing 10 ms increments along a /ba/-/pa/ voice-onset-time (VOT) continuum were used to evoke the responses. Each participant's ability to discriminate the speech tokens was also assessed. RESULTS: Compared with younger participants, older adults with and without hearing loss had more difficulty discriminating 10 ms VOT contrasts. In addition, both older groups elicited abnormal neural response patterns. There were no significant age-related findings for P1 latency; however, N1 latencies were prolonged for both older groups in response to stimuli with increased VOT durations. Also, P2 latencies were delayed for both older groups. The presence of age-related hearing loss resulted in a significant increase in N1 amplitude in response to voiceless stimuli. CONCLUSIONS: Aging and age-related hearing loss alter temporal response properties in the central auditory system. Because both older groups had difficulty discriminating these same speech stimuli, we conclude that some of the perceptual difficulties described by older adults might be due to age-related changes regulating excitatory and inhibitory processes. SIGNIFICANCE: Some of the speech understanding difficulties expressed by elderly adults may be related to impaired temporal precision in the aging auditory system. This might explain why older adults frequently complain that wearing a hearing aid makes speech louder, but does not necessarily improve their ability to understand speech.     

Differential activation of the striatum for decision making and outcomes in a monetary task with gain and loss

We examined brain activation for decision making and for different monetary outcomes in a two-alternative choice task with monetary rewards and punishments. Brain hemodynamic changes were monitored by functional MRI (fMRI) when seventeen healthy volunteers performed a task in which they were required to press one of two buttons (button 1 or 2) which increased or decreased their previously endowed money depending upon accord or disaccord with the number (1 or 2) which was displayed later. The amount of money subjects gained or lost was large when they selected 2 and small when they selected 1. They were informed in advance that the order of the appearance of 1 or 2 at outcome phase was predetermined and random, irrespective of their selection, and that the expected value was mathematically zero for both selecting 1 and 2. Results of fMRI showed that bilateral putamen and nucleus accumbens were more activated when selecting large gain or loss option than selecting small gain or loss option, and the right putamen and nucleus accumbens were more activated for gain outcome than for loss outcome. No significantly different activation of the striatum was found between large gain outcome and small gain outcome, suggesting that activity of the striatum at outcome phase was insensitive for reward magnitude when expectation by subject was already performed. We also found that activations of the bilateral putamen were correlated parametrically with stock amount of money.     

Neural response during anticipation of monetary loss is elevated in adult attention deficit hyperactivity disorder

Objectives: Risky behaviour seriously impacts the life of adult patients with attention deficit hyperactivity disorder (ADHD). Such behaviours have often been attributed to their exaggerated reward seeking, but dysfunctional anticipation of negative outcomes might also play a role. Methods: The present study compared adult patients with ADHD (n?=?28) with matched healthy controls (n?=?28) during anticipation of monetary losses versus gains while undergoing functional magnetic resonance imaging (fMRI) and skin conductance recording. Results: Skin conductance was higher during anticipation of losses compared to gains in both groups. Affective ratings of predictive cues did not differ between groups. ADHD patients showed increased activity in bilateral amygdalae, left anterior insula (region of interest analysis) and left temporal pole (whole brain analysis) compared to healthy controls during loss versus gain anticipation. In the ADHD group higher insula and temporal pole activations went along with more negative affective ratings. Conclusions: Neural correlates of loss anticipation are not blunted but rather increased in ADHD, possibly due to a life history of repeated failures and the respective environmental sanctions. Behavioural adaptations to such losses, however, might differentiate them from controls: future research should study whether negative affect might drive more risk seeking than risk avoidance.     

Motor and non-motor features of Parkinson's disease that predict persistent drug-induced Parkinsonism

BackgroundDrug-induced Parkinsonism is common, causes significant morbidity, and can be clinically indistinguishable from idiopathic Parkinson's disease. Additionally, drug-induced Parkinsonism may, in some cases, represent “unmasking” of incipient Parkinson's disease. Clinical features or tests that distinguish degenerative from pharmacologic Parkinsonism are needed.MethodsWe performed a retrospective case-control study of 97 drug-induced Parkinsonism subjects and 97 age-matched patients with Parkinson's disease. We compared the frequency of subjective motor and non-motor complaints, objective motor findings (Unified Parkinson's Disease Rating Scale Part III) and, where available, objective olfactory tests. We also performed a nested case-control study wherein we compared these same features between drug-induced Parkinsonism patients based on whether or not they recovered after changing the offending agent.ResultsNon-motor symptoms including constipation and sexual dysfunction were more common in Parkinson's disease than in drug-induced Parkinsonism. While total motor scores were similar between groups, Postural Instability-Gait Difficulty scores were also higher in Parkinson's disease. Features that were significantly different or showed a trend towards significance in both comparisons included subjective loss of facial expression, dream-enactment behavior, autonomic complaints and Postural Instability-Gait Difficulty scores. Hyposmia was more common in Parkinson's disease and was strongly predictive of persistent drug-induced Parkinsonism after therapy change (odds ratio 30.3, 95% confidence interval: 1.5–500, p = 0.03).ConclusionsA constellation of motor and non-motor features may differentiate unmasked Parkinson's disease from drug-induced Parkinsonism. In particular, olfactory testing may offer a simple and inexpensive method to help predict outcomes in drug-induced Parkinsonism and, potentially, identify a cohort of pre-motor Parkinson's disease.     

Increased feeding and hyperglycemia elicited by intracerebroventricular 5-thioglucose

5-Thioglucose (5-TG) is a glucose analogue in which sulfur is substituted for the pyranose ring oxygen. Intracerebroventricular infusion of 5-TG caused prompt initiation of feeding and a marked rise in plasma glucose concentration at doses as low as 0.54 mumol (106 microgram). 5-TG is, therefore, more potent for eliciting feeding than any other previously tested glucose antimetabolite. The potency of 5-TG for eliciting feeding should make 5-TG a useful tool for localizing brain glucoreceptors which participate in the control of food intake.