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Brain Sci., Volume 2, Issue 3 (September 2012), Pages 267-433

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Research

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Open AccessArticle The N400 and Late Positive Complex (LPC) Effects Reflect Controlled Rather than Automatic Mechanisms of Sentence Processing
Brain Sci. 2012, 2(3), 267-297; doi:10.3390/brainsci2030267
Received: 21 June 2012 / Revised: 16 July 2012 / Accepted: 1 August 2012 / Published: 14 August 2012
Cited by 4 | PDF Full-text (1036 KB) | HTML Full-text | XML Full-text
Abstract
This study compared automatic and controlled cognitive processes that underlie event-related potentials (ERPs) effects during speech perception. Sentences were presented to French native speakers, and the final word could be congruent or incongruent, and presented at one of four levels of degradation [...] Read more.
This study compared automatic and controlled cognitive processes that underlie event-related potentials (ERPs) effects during speech perception. Sentences were presented to French native speakers, and the final word could be congruent or incongruent, and presented at one of four levels of degradation (using a modulation with pink noise): no degradation, mild degradation (2 levels), or strong degradation. We assumed that degradation impairs controlled more than automatic processes. The N400 and Late Positive Complex (LPC) effects were defined as the differences between the corresponding wave amplitudes to incongruent words minus congruent words. Under mild degradation, where controlled sentence-level processing could still occur (as indicated by behavioral data), both N400 and LPC effects were delayed and the latter effect was reduced. Under strong degradation, where sentence processing was rather automatic (as indicated by behavioral data), no ERP effect remained. These results suggest that ERP effects elicited in complex contexts, such as sentences, reflect controlled rather than automatic mechanisms of speech processing. These results differ from the results of experiments that used word-pair or word-list paradigms. Full article
Open AccessArticle The Hepatocyte Growth Factor/c-Met Antagonist, Divalinal-Angiotensin IV, Blocks the Acquisition of Methamphetamine Dependent Conditioned Place Preference in Rats
Brain Sci. 2012, 2(3), 298-318; doi:10.3390/brainsci2030298
Received: 9 May 2012 / Revised: 6 July 2012 / Accepted: 10 August 2012 / Published: 20 August 2012
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Abstract
The use of methamphetamine (MA) is increasing in the U.S. and elsewhere around the world. MA’s capacity to cause addiction significantly exceeds other psychostimulant drugs, and its use negatively impacts learning and memory. Recently, attempts have been made to interfere with the [...] Read more.
The use of methamphetamine (MA) is increasing in the U.S. and elsewhere around the world. MA’s capacity to cause addiction significantly exceeds other psychostimulant drugs, and its use negatively impacts learning and memory. Recently, attempts have been made to interfere with the presumed mechanism(s) underlying the establishment of drug-induced memory consolidation. The majority of these studies have employed matrix metalloproteinase (MMP) inhibitors to disrupt MMP-induced extracellular matrix molecule dependent synaptic reconfiguration, or GABA receptor agonists. The present investigation utilized an angiotensin IV (AngIV) analogue, Divalinal-AngIV (divalinal), to disrupt acquisition of MA-induced dependence in rats as measured using the conditioned place preference paradigm. Results indicate that both acute and chronic intracerebroventricular infusion of divalinal prior to each daily subcutaneous injection of MA prevented acquisition. However, divalinal was unable to prevent MA-induced reinstatement after prior acquisition followed by extinction trials. These results indicate that prevention of MA dependence can be accomplished by blockade of the brain AT4 receptor subtype. On the other hand, once MA-induced memory consolidation is in place divalinal appears to be ineffective. Mechanistic studies indicated that divalinal is a potent inhibitor of the hepatocyte growth factor (HGF)/c-Met receptor system, and thus it appears that a functional HGF/c-Met system is required for the acquisition of MA-mediated conditioned place preference. Full article
(This article belongs to the Special Issue Addiction and Neuroadaptation)
Open AccessArticle Neurochemical Analysis of Primary Motor Cortex in Chronic Low Back Pain
Brain Sci. 2012, 2(3), 319-331; doi:10.3390/brainsci2030319
Received: 8 June 2012 / Revised: 8 August 2012 / Accepted: 14 August 2012 / Published: 21 August 2012
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Abstract
The involvement of the primary motor cortex (M1) in chronic low back pain (LBP) is a relatively new concept. Decreased M1 excitability and an analgesic effect after M1 stimulation have been recently reported. However, the neurochemical changes underlying these functional M1 changes [...] Read more.
The involvement of the primary motor cortex (M1) in chronic low back pain (LBP) is a relatively new concept. Decreased M1 excitability and an analgesic effect after M1 stimulation have been recently reported. However, the neurochemical changes underlying these functional M1 changes are unknown. The current study investigated whether neurochemicals specific to neurons and glial cells in both right and left M1 are altered. N-Acetylaspartate (NAA) and myo-inositol (mI) were measured with proton magnetic resonance spectroscopy in 19 subjects with chronic LBP and 14 healthy controls. We also examined correlations among neurochemicals within and between M1 and relationships between neurochemical concentrations and clinical features of pain. Right M1 NAA was lower in subjects with LBP compared to controls (p = 0.008). Left M1 NAA and mI were not significantly different between LBP and control groups. Correlations between neurochemical concentrations across M1s were different between groups (p = 0.008). There were no significant correlations between M1 neurochemicals and pain characteristics. These findings provide preliminary evidence of neuronal depression and altered neuronal-glial interactions across M1 in chronic LBP. Full article
Open AccessArticle Long-Term Effects of Physical Exercise on Verbal Learning and Memory in Middle-Aged Adults: Results of a One-Year Follow-Up Study
Brain Sci. 2012, 2(3), 332-346; doi:10.3390/brainsci2030332
Received: 21 May 2012 / Revised: 21 July 2012 / Accepted: 20 August 2012 / Published: 27 August 2012
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Abstract
A few months of physical exercise have been shown to increase cognition and to modulate brain functions in previously sedentary, mainly older adults. However, whether the preservation of newly gained cognitive capacities requires an active maintenance of the achieved fitness level during [...] Read more.
A few months of physical exercise have been shown to increase cognition and to modulate brain functions in previously sedentary, mainly older adults. However, whether the preservation of newly gained cognitive capacities requires an active maintenance of the achieved fitness level during the intervention is not yet known. The aim of the present study was to test whether cardiovascular fitness one year after an exercise intervention was linked to cognitive variables. Twenty-five healthy participants (42–57 years of age) took part in a follow-up assessment one year after the end of a supervised exercise intervention. Measurements included a cardiovascular fitness test, psychometric tests of verbal learning and memory and selective attention as well as questionnaires assessing physical activity and self-efficacy beliefs. Recognition scores of participants with higher cardiovascular fitness at follow-up did not change significantly during the follow-up period; however, the scores of participants with lower cardiovascular fitness decreased. One year after the end of the physical training intervention, previously sedentary participants spent more hours exercising than prior to the intervention. The time participants spent exercising correlated with their self-efficacy beliefs. These results demonstrate a direct link between verbal learning and cardiovascular fitness and show that positive effects of physical interventions on learning and memory do need an active maintenance of cardiovascular fitness. Full article
(This article belongs to the Special Issue Exercise and Brain Function)
Open AccessArticle Long-Term Effects of Chronic Oral Ritalin Administration on Cognitive and Neural Development in Adolescent Wistar Kyoto Rats
Brain Sci. 2012, 2(3), 375-404; doi:10.3390/brainsci2030375
Received: 3 July 2012 / Revised: 24 August 2012 / Accepted: 28 August 2012 / Published: 12 September 2012
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Abstract
The diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) often results in chronic treatment with psychostimulants such as methylphenidate (MPH, Ritalin®). With increases in misdiagnosis of ADHD, children may be inappropriately exposed to chronic psychostimulant treatment during development. The aim of [...] Read more.
The diagnosis of Attention Deficit Hyperactivity Disorder (ADHD) often results in chronic treatment with psychostimulants such as methylphenidate (MPH, Ritalin®). With increases in misdiagnosis of ADHD, children may be inappropriately exposed to chronic psychostimulant treatment during development. The aim of this study was to assess the effect of chronic Ritalin treatment on cognitive and neural development in misdiagnosed “normal” (Wistar Kyoto, WKY) rats and in Spontaneously Hypertensive Rats (SHR), a model of ADHD. Adolescent male animals were treated for four weeks with oral Ritalin® (2 × 2 mg/kg/day) or distilled water (dH2O). The effect of chronic treatment on delayed reinforcement tasks (DRT) and tyrosine hydroxylase immunoreactivity (TH-ir) in the prefrontal cortex was assessed. Two weeks following chronic treatment, WKY rats previously exposed to MPH chose the delayed reinforcer significantly less than the dH2O treated controls in both the DRT and extinction task. MPH treatment did not significantly alter cognitive performance in the SHR. TH-ir in the infralimbic cortex was significantly altered by age and behavioural experience in WKY and SHR, however this effect was not evident in WKY rats treated with MPH. These results suggest that chronic treatment with MPH throughout adolescence in “normal” WKY rats increased impulsive choice and altered catecholamine development when compared to vehicle controls. Full article
(This article belongs to the Special Issue Addiction and Neuroadaptation)
Open AccessCommunication There Are Conscious and Unconscious Agendas in the Brain and Both Are Important—Our Will Can Be Conscious as Well as Unconscious
Brain Sci. 2012, 2(3), 405-420; doi:10.3390/brainsci2030405
Received: 28 June 2012 / Revised: 28 August 2012 / Accepted: 30 August 2012 / Published: 18 September 2012
Cited by 1 | PDF Full-text (198 KB) | HTML Full-text | XML Full-text
Abstract
I have been asked to write a few words on consciousness in this editorial issue. My thoughts on consciousness will focus on the relation between consciousness and will. Consciousness is not an epiphenomenon as some people believe—it is not a psychological construct [...] Read more.
I have been asked to write a few words on consciousness in this editorial issue. My thoughts on consciousness will focus on the relation between consciousness and will. Consciousness is not an epiphenomenon as some people believe—it is not a psychological construct either. Consciousness is a brain function. With deeper thought it is even more than that—a brain state. Writing this, I am in a conscious state, I hope at least. In every day philosophy, a close connection of consciousness with will is ventured, and is expressed in the term “conscious free will”. However, this does not mean that our will is totally determined and not free, be it conscious or unconscious. Total determinists postulate total freedom from nature in order to speak of free will. Absolute freedom from nature is an a priori impossibility; there is no way to escape from nature. However, we have relative freedom, graded freedom, freedom in degrees, enabling us to make responsible decisions and be captains of our own destiny. We are not totally determined. We can upregulate our degrees of freedom by self-management or we can downregulate them by self-mismanagement. In the present communication consciousness and the unconscious are discussed in their various aspects and interactions. Full article
Open AccessArticle Repeated Episodes of Heroin Cause Enduring Alterations of Circadian Activity in Protracted Abstinence
Brain Sci. 2012, 2(3), 421-433; doi:10.3390/brainsci2030421
Received: 31 July 2012 / Revised: 4 September 2012 / Accepted: 11 September 2012 / Published: 20 September 2012
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Abstract
Opiate withdrawal is followed by a protracted abstinence syndrome consisting of craving and physiological changes. However, few studies have been dedicated to both the characterization and understanding of these long-term alterations in post-dependent subjects. The aim of the present study was to [...] Read more.
Opiate withdrawal is followed by a protracted abstinence syndrome consisting of craving and physiological changes. However, few studies have been dedicated to both the characterization and understanding of these long-term alterations in post-dependent subjects. The aim of the present study was to develop an opiate dependence model, which induces long-lasting behavioral changes in abstinent rats. Here, we first compared the effects of several protocols for the induction of opiate dependence (morphine pellets, repeated morphine or heroin injections) on the subsequent response to heroin challenges (0.25 mg/kg) at different time points during abstinence (3, 6, 9 and 18 weeks). In a second set of experiments, rats were exposed to increasing doses of heroin and subsequently monitored for general circadian activity up to 20 weeks of abstinence. Results show that heroin injections rather than the other methods of opiate administration have long-term consequences on rats’ sensitivity to heroin with its psychostimulant effects persisting up to 18 weeks of abstinence. Moreover, intermittent episodes of heroin dependence rather than a single exposure produce enduring alteration of the basal circadian activity both upon heroin cessation and protracted abstinence. Altogether, these findings suggest that the induction of heroin dependence through intermittent increasing heroin injections is the optimal method to model long-term behavioral alterations during protracted abstinence in rats. This animal model would be useful in further characterizing long-lasting changes in post-dependent subjects to help understand the prolonged vulnerability to relapse. Full article
(This article belongs to the Special Issue Addiction and Neuroadaptation)

Review

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Open AccessReview Internet and Gaming Addiction: A Systematic Literature Review of Neuroimaging Studies
Brain Sci. 2012, 2(3), 347-374; doi:10.3390/brainsci2030347
Received: 28 June 2012 / Revised: 24 August 2012 / Accepted: 28 August 2012 / Published: 5 September 2012
Cited by 57 | PDF Full-text (242 KB) | HTML Full-text | XML Full-text
Abstract
In the past decade, research has accumulated suggesting that excessive Internet use can lead to the development of a behavioral addiction. Internet addiction has been considered as a serious threat to mental health and the excessive use of the Internet has been [...] Read more.
In the past decade, research has accumulated suggesting that excessive Internet use can lead to the development of a behavioral addiction. Internet addiction has been considered as a serious threat to mental health and the excessive use of the Internet has been linked to a variety of negative psychosocial consequences. The aim of this review is to identify all empirical studies to date that used neuroimaging techniques to shed light upon the emerging mental health problem of Internet and gaming addiction from a neuroscientific perspective. Neuroimaging studies offer an advantage over traditional survey and behavioral research because with this method, it is possible to distinguish particular brain areas that are involved in the development and maintenance of addiction. A systematic literature search was conducted, identifying 18 studies. These studies provide compelling evidence for the similarities between different types of addictions, notably substance-related addictions and Internet and gaming addiction, on a variety of levels. On the molecular level, Internet addiction is characterized by an overall reward deficiency that entails decreased dopaminergic activity. On the level of neural circuitry, Internet and gaming addiction led to neuroadaptation and structural changes that occur as a consequence of prolonged increased activity in brain areas associated with addiction. On a behavioral level, Internet and gaming addicts appear to be constricted with regards to their cognitive functioning in various domains. The paper shows that understanding the neuronal correlates associated with the development of Internet and gaming addiction will promote future research and will pave the way for the development of addiction treatment approaches. Full article
(This article belongs to the Special Issue Addiction and Neuroadaptation)

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