Figure 2 - uploaded by Wim J Riedel
Content may be subject to copyright.
Means (± SE) of the delayed recall and delayed recognition assessments of the VVLT at baseline (t 0 ) and at 5 (t 5 ) and 9 h (t 9 ) after administration of the AA mixture. Delayed recognition performance is depicted in the top box, delayed recall in the lower box. X-axis labels t x→y denote time of word list presentation (x) and time of assessment (y)
Source publication
Animal and human studies have provided evidence for serotonergic modulation of cognitive processes. However, the exact nature of this relationship is not clear. We used the acute tryptophan depletion (ATD) method to investigate the effects of lowered serotonin synthesis on cognitive functions in 17 healthy young volunteers. The study was conducted...
Context in source publication
Context 1
... results of the delayed recall and recognition trials are depicted in Fig. 2, immediate recall scores and delayed recognition reaction times are listed in Table 1. Delayed recall in the ATD group was significantly lower than that of the placebo group. Note however, that ATD was not induced until after delayed recall at t 0 (t 0→0 ). Therefore, effects of ATD can only be observed at t 5 (t 0→5 ) and not at t 0 ...
Similar publications
The clinical effects of the simultaneous application of nonlinear frequency compression and dichotic hearing on people with hearing impairments have not been evaluated previously. In this study, the clinical effects of the simultaneous application of these two techniques on the recognition of consonant-vowel-consonant (CVC) words with fricatives we...
It is well known that the planum temporale (PT) area in the posterior temporal lobe carries out spectro-temporal analysis of auditory stimuli, which is crucial for speech, for example. There are suggestions that the PT is also involved in auditory attention, specifically in the discrimination and selection of stimuli from the left and right ear. Ho...
Macrophagic myofasciitis (MMF) is an emerging condition characterized by specific muscle lesions assessing abnormal long-term persistence of aluminum hydroxide within macrophages at the site of previous immunization. Affected patients usually are middle-aged adults, mainly presenting with diffuse arthromyalgias, chronic fatigue, and marked cognitiv...
Introduction Elderly individuals with bilateral hearing loss often do not use hearing aids in both ears. Because of this, dichotic tests to assess hearing in this group may help identify peculiar degenerative processes of aging and hearing aid selection.
Objective To evaluate dichotic hearing for a group of elderly hearing aid users who did not ad...
Patients with macrophagic myofasciitis (MMF) present with diffuse arthromyalgias, chronic fatigue, and cognitive disorder. Representative features of MMF-associated cognitive dysfunction include attentional dysfunction, dysexecutive syndrome, visual memory deficit and left ear extinction. Our study aims to reevaluate the neuropsychological profile...
Citations
... Tryptophan is an essential amino acid that plays a crucial role in brain function due to its activity as a precursor for the synthesis of the neurotransmitter serotonin (5-hydroxytryptamine). Numerous studies have demonstrated the positive effects of tryptophan on cognition [9][10][11][12]. According to a study [13], the combination of the non-proteinic amino acid L-theanine and caffeine has been demonstrated to enhance focused attention during a cognitively demanding activity. ...
The results showed that using AA compositions during the longitude period significantly affected cognitive functions in particular memory, speed of reactions and attention and that AAs processed by radiation of a cold plasma had an even more substantial effect.
... Additionally, decreased serotonin transporter binding in the right dlPFC has been linked to poorer interference control in healthy controls . In contrast, acutely induced depletion of dopamine and serotonin has been found to improve interference control in healthy volunteers (Evers et al., 2006;Schmitt et al., 2000;Scholes et al., 2007), but there are also a few conflicting reports (Danjou et al., 1990;Gallagher et al., 2003). The stimulation of noradrenergic neurons of the locus coeruleus (LC) increased selective attention via projections to the dorsal medial PFC in Table 1 The primary mechanism of acute and chronic effects of amphetamine-type stimulants (ATS) on the monoaminergic system and associated brain regions that are most relevant for cognition. ...
In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1,873 ATS users and 1,905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; future research should further elucidate its functional role in ATS users.
... Among these, the most well-characterized neuromodulators include acetylcholine (ACh), serotonin (5-HT), norepinephrine (NE), and dopamine (DA), each of which exerts important and varied effects on mPFC function. For example, disruptions to cholinergic input from the basal forebrain have detrimental outcomes on attention (Robbins et al., 1989;Pang et al., 1993;Voytko et al., 1994;McGaughy et al., 2002;Dalley, 2004;Newman and McGaughy, 2008;Hasselmo and Sarter, 2011), whereas impaired serotonergic innervation from the medial and dorsal raphe nuclei has opposing effects (Schmitt et al., 2000;Gallagher et al., 2003;Wingen et al., 2007). In contrast, NE and DA appear to have synergistic effects -prior studies have suggested that prefrontal cortical NE transmission is necessary for DA release in the mPFC (Ventura et al., 2003(Ventura et al., , 2005(Ventura et al., , 2007, and DA can be taken up through the NE transporter Morón et al., 2002). ...
Dysfunction in dopamine (DA) signaling contributes to neurological disorders ranging from drug addiction and schizophrenia to depression and Parkinson’s Disease. How might impairment of one neurotransmitter come to effect these seemingly disparate diseases? One potential explanation is that unique populations of DA-releasing cells project to separate brain regions that contribute to different sets of behaviors. Though dopaminergic cells themselves are spatially restricted to the midbrain and constitute a relatively small proportion of all neurons, their projections influence many brain regions. DA is particularly critical for the activity and function of medial prefrontal cortical (mPFC) ensembles. The midbrain and mPFC exhibit reciprocal connectivity – the former innervates the mPFC, and in turn, the mPFC projects back to the midbrain. Viral mapping studies have helped elucidate the connectivity within and between these regions, which likely have broad implications for DA-dependent behaviors. In this review, we discuss advancements in our understanding of the connectivity between the mPFC and midbrain DA system, focusing primarily on rodent models.
... TRP depletion as a pharmacological 5-HT deficiency model in humans, commonly results in impairments of declarative memory. In verbal learning tests, the effects were most prominent at delayed recall, with fewer words recollected after TRP depletion (Amin et al., 2006;Borghans et al., 2017;Harrison et al., 2004;Klaassen et al., 1999;McAllister-Williams et al., 2002;Sambeth et al., 2007Sambeth et al., , 2009Schmitt et al., 2000). There are only two studies, which at least partly, failed to replicate this finding (Evers et al., 2005;Hughes et al., 2003). ...
... In contrast to verbal learning, immediate verbal recall was mostly either unaffected (Harrison et al., 2004;Klaassen et al., 1999;Schmitt et al., 2000), or only females were found to be impaired (Borghans et al., 2017;Helmbold et al., 2013;Mace et al., 2008;Sambeth et al., 2007). The specific greater vulnerability of females to the effects of TRP restriction likely involves interactions with estrogen. ...
... Effects of TRP depletion on word recognition were less consistent. Recognition deficits were reported to be most pronounced after some hours delay Rubinsztein et al., 2001;Sambeth et al., 2007;Schmitt et al., 2000;van der Veen et al., 2006). Evers et al. (2005) found increased reaction times in delayed visual word recognition, however, other examinations failed to find differences in comparison to control conditions (Borghans et al., 2017;Harrison et al., 2004;Helmbold et al., 2013;Klaassen et al., 1999;Sambeth et al., 2009). ...
The serotonergic system is involved in diverse cognitive functions including memory. Of particular importance to daily life are declarative memories that contain information about personal experiences, general facts, and events. Several psychiatric or neurological diseases, such as depression, attention-deficit-hyperactivity disorder (ADHD), and dementia, show alterations in serotonergic signalling and attendant memory disorders. Nevertheless, understanding serotonergic neurotransmission and its influence on memory remained a challenge until today.
In this systematic review, we summarize recent psychopharmacological studies in animals and humans from a psychological memory perspective, in consideration of task-specific requirements. This approach has the advantage that comparisons between serotonin (5-HT)-related neurochemical mechanisms and manipulations are each addressing specific mnemonic circuits. We conclude that applications of the same 5-HT-related treatments can differentially affect unrelated tasks of declarative memories. Moreover, the analysis of specific mnemonic phases (e.g., encoding vs. consolidation) reveals opposing impacts of increased or decreased 5-HT tones, with low 5-HT supporting spatial encoding but impairing the consolidation of objects and verbal memories. Promising targets for protein synthesis-dependent consolidation enhancements include 5-HT4 receptor agonists and 5-HT6 receptor antagonists, with the latter being of special interest for the treatment of age-related decline. Further implications are pointed out as base for the development of novel therapeutic targets for memory impairment of neuropsychiatric disorders.
... Positron emission tomography has shown that in the hippocampus and medial prefrontal cortex of elderly individuals there is a loss of 5-HT2A (HTR2A) receptors (Sheline et al., 2002), while experimental studies in rodents have shown that both short-and long-term memory dependent on hippocampal activity are influenced by the improved "tone" of serotonin receptors (Haider et al., 2007). In addition, the depletion of tryptophan (a precursor of serotonin synthesis) results in a decrease in available serotonin that impacts memory consolidation Olvera-Cortés et al., 1998;Schmitt et al., 2000). Taking these antecedents into consideration, the relationship between a functional polymorphism in the serotonin 5-HT2A receptor and episodic memory has been explored. ...
... None of these studies reported a significant effect of ATD on PRL performance. [100][101][102] Using the Stroop test, three investigations reported improvements in selective attention following ATD administration, 100,103,104 with the ATD increasing the BOLD signal in the anterior cingulate cortex (ACC) and precuneus. A fourth study did not find a behavioural effect but did report increased activation in the ACC and PFC. ...
The serotonergic precursor tryptophan and the dopaminergic precursor tyrosine have been shown to be important modulators of mood, behaviour and cognition. Specifically, research on the function of tryptophan has characterised this molecule as particularly relevant in the context of pathological disorders such as depression. Moreover, a large body of evidence has now been accumulated to suggest that tryptophan may also be involved in executive function and reward processing. Despite some clear differentiation with tryptophan, the data reviewed in this paper illustrates that tyrosine shares similar functions with tryptophan in the regulation of executive function and reward, and that these processes in turn, rather than acting in isolation, causally influence each other.
... The latter has been assumed to be a more accurate indicator of brain 5-HT synthesis rate than absolute plasma levels of TRP (Oldendorf and Szabo, 1976;Scholes et al., 2007). This reduction in TRP/ P LNAA ratio is comparable to previous studies (Schmitt et al., 2000;Scholes et al., 2007), demonstrating the efficacy of the implemented ATD procedure in the present study. ...
Previous research on central nervous serotonin (5-HT) function provided evidence for a substantial involvement of 5-HT in the regulation of brain circuitries associated with cognitive and affective processing. The underlying neural networks comprise core subcortical/cortical regions such as amygdala and medial prefrontal cortex, which are assumed to be modulated amongst others by 5-HT. Beside the use of antidepressants, acute tryptophan depletion (ATD) is a widely accepted technique to manipulate of 5-HT synthesis and its respective metabolites in humans by means of a dietary and non-pharmacological tool. We used a double-blind, randomized, cross-over design with two experimental challenge conditions, i.e. ATD and tryptophan (TRP) supplementation (TRYP+) serving as a control. The aim was to perturb 5-HT synthesis and to detect its impact on brain functional connectivity (FC) of the upper serotonergic raphe nuclei, the amygdala and the ventromedial prefrontal cortex as well as on network organization using resting state fMRI. 30 healthy adult female participants (age: M = 24.5 ± 4.4 yrs) were included in the final analysis. ATD resulted in a 90% decrease of TRP in the serum relative to baseline. Compared to TRYP + for the ATD condition a significantly lower FC of the raphe nucleus to the frontopolar cortex was detected, as well as greater functional coupling between the right amygdala and the ventromedial prefrontal cortex. FC of the raphe nucleus correlated significantly with the magnitude of TRP changes for both challenge conditions (ATD & TRYP+). Network-based statistical analysis using time series from 260 independent anatomical ROIs revealed significantly greater FC after ATD compared to TRYP+ in several brain regions being part of the default-mode (DMN) and the executive-control networks (ECN), but also of salience or visual networks. Finally, we observed an impact of ATD on the rich-club organization in terms of decreased rich-club coefficients compared to TRYP+. In summary we could confirm previous findings that the putative decrease in brain 5-HT synthesis via ATD significantly alters FC of the raphe nuclei as well as of specific subcortical/cortical regions involved in affective, but also in cognitive processes. Moreover, an ATD-effect on the so-called rich-club organization of some nodes with the high degree was demonstrated. This may indicate effects of brain 5-HT on the integration of information flow from several brain networks.
... In this protocol, the amount of amino acids is adapted to body weight and is less than what is used in other studies (Young et al., 1985). The main advantage of this mixture is that it reduces the risk of nausea that has been reported earlier (Booij et al., 2005;Cools et al., 2005;Schmitt et al., 2000) while still effectively changing 5-HT levels (Biskup et al., 2012;Dingerkus et al., 2012). The dose of large neutral amino acids (LNAAs) was the same for all conditions and consisted of L-phenylalanine (132 mg/kg), L-leucine (132 mg/kg), L-isoleucine (84 mg/kg), L-methionine (50 mg/kg), L-valine (96 mg/kg), L-threonine (60 mg/kg) and L-lysine (96 mg/kg). ...
Background: Serotonin has been implicated in impulsive behaviours such as temporal discounting. While animal studies and theoretical approaches suggest that reduced tonic serotonin levels increase temporal discounting rates and vice versa, evidence from human studies is scarce and inconclusive. Furthermore, an important modulator of serotonin signalling, a genetic variation in the promoter region of the serotonin transporter gene (5-HTTLPR), has not been investigated for temporal discounting so far.
Objective: First, the purpose of this study was to test for a significant association between 5-HTTLPR and temporal discounting. Second, we wished to investigate the effect of high/low tonic serotonin levels on intertemporal choice and blood oxygen-level-dependent response, controlling for 5-HTTLPR.
Methods: We tested the association of 5-HTTLPR with temporal discounting rates using an intertemporal choice task in 611 individuals. We then manipulated tonic serotonin levels with acute tryptophan interventions (depletion, loading, balanced) in a subsample of 45 short (S)-allele and 45 long (L)/L-allele carriers in a randomised double-blind crossover design using functional magnetic resonance imaging and an intertemporal choice task.
Results: Overall, we did not find any effect of serotonin and 5-HTTLPR on temporal discounting rates or the brain networks associated with valuation and cognitive control.
Conclusion: Our findings indicate that serotonin may not be directly involved in choices including delays on longer timescales such as days, weeks or months. We speculate that serotonin plays a stronger role in dynamic intertemporal choice tasks where the delays are on a timescale of seconds and hence are therefore directly experienced during the experiment.
... A negative component decrease in the oddball paradigm has also been found in the 50% serotonin depletion condition after the para-chlorophenylalanine administration in rats (Ehlers et al., 1991). On the contrary, some studies in humans indicate an improved attention and executive functions (Coull et al., 1995;Schmitt et al., 2000;Murphy et al., 2002), an increased MMN amplitude and a decreased MMNm latency (Kähkönen et al., 2005) after the ATD. Although some studies show increased MMN amplitude with monoaminergic systems activity decrease, but the role of this system in the MMN generation remains unclear. ...
The trace amine-associated receptor 1 (TAAR1) is a G protein-coupled receptor widely expressed in the mammalian brain, particularly in limbic system and monoaminergic areas. It has proven to be an important modulator of dopaminergic, serotoninergic, and glutamatergic neurotransmission and is considered to be a potential useful target for the pharmacotherapy of neuropsychiatric disorders, including schizophrenia. One of the promising schizophrenia endophenotypes is a deficit in neurocognitive abilities manifested as mismatch negativity (MMN) deficit. This study examines the effect of TAAR1 partial agonist RO5263397 on the MMN-like response in freely moving C57BL/6 mice. Event-related potentials (ERPs) were recorded from awake mice in the oddball paradigm before and after RO5263397 administration. The RO5263397 (but not saline) administration increased the N40 amplitude in response to deviant stimuli. That provided the MMN-like difference at the 36–44 ms interval after the injection. The pitch deviance-elicited changes before the injection and in the control paradigm were established for the P68 component. After TAAR1 agonist administration the P68 amplitude in response both to standard and deviant stimuli was increased. These results suggest that the MMN-like response in mice may be modulated through TAAR1-dependent processes (possibly acting through the direct or indirect glutamate NMDA receptor modulation), indicating the TAAR1 agonists potential antipsychotic and pro-cognitive activity.
... The mean initial body weight of rats was 267.83 ± 2.48 g and on the last day of testing in MWM it reached 334.35 ± 2.88 g. Analysis of variance showed no significant differences between groups in both initial (F (3,36) = 0.84, p > 0.05) and final (F (3,36) = 0.44, p > 0.05) body weight. Moreover, no significant differences between groups in body weight increase during the whole period between the first and the last measurement of body weight were found (F (3, 36) = 2.17, p > 0.05) as assessed by repeated measures ANOVA. ...
... The mean initial body weight of rats was 267.83 ± 2.48 g and on the last day of testing in MWM it reached 334.35 ± 2.88 g. Analysis of variance showed no significant differences between groups in both initial (F (3,36) = 0.84, p > 0.05) and final (F (3,36) = 0.44, p > 0.05) body weight. Moreover, no significant differences between groups in body weight increase during the whole period between the first and the last measurement of body weight were found (F (3, 36) = 2.17, p > 0.05) as assessed by repeated measures ANOVA. ...
... Welch's ANOVA showed significant differences between groups in total distance travelled (F (3, 84.29) = 3.21 W , p = 0.027) and transfer latency (F (3, 82.30) = 5.25 W , p = 0.003) (Fig. 4A-B). Significant differences between groups were also found in number of defecations (F (3,36) = 3.29, p = 0.032). According to post-hoc tests, rats from the D-Gal group travelled significantly longer distances to find the platform as compared to control group (Con: 2.42 ± 0.38 m vs. D-Gal: 4.68 ± 0.71 m, p < 0.05, post-hoc GH) which has also direct reflection in longer transfer latencies in D-Gal rats (Con: 10.05 ± 1.28 s vs. D-Gal: 22.41 ± 3.30 s, p < 0.01, post-hoc GH). ...
Protocatechuic acid (PCA) is a phenolic compound believed to have neuroprotective and procognitive activity. D-Galactose (D-Gal) is a sugar, which administered to mammals can induce cognitive deficits. The first aim of this study was to confirm the effectiveness of D-Gal administered orally in inducing cognitive impairment in rats and describe how it affects the concentration of neurotransmitters in rats’ brain. The second aim was to evaluate the influence of PCA on learning, memory and neurotransmission in D-Gal-exposed rats. Memory impairment was induced by long-term administration of D-Gal (100 mg/kg body weight/day) directly via oral gavage. PCA (50 or 100 mg/kg body weight/day, respectively) was administered in drinking water. Morris Water Maze test (MWM) to assess learning and spatial memory was initiated after 38 days of treatment and lasted for 10 days. The concentrations of monoamines and their metabolites were evaluated in selected brain regions using high performance liquid chromatography. D-Gal significantly impaired cognitive performance during the acquisition and recall of MWM compared to control rats and changed concentrations of cortical serotonin as well as its cortical and hippocampal turnover. The turnover of dopamine was also influenced by D-Gal. Simultaneously, PCA was found to improve retrieval of acquired information in MWM and to restore brain serotonergic and dopaminergic turnover dysregulated by D-Gal. These findings confirm the usefulness of oral D-Gal in eliciting rat model of mild memory impairment and show that long-term administration of PCA can be beneficial in reversing detrimental changes related to cognitive deficiencies.
