Showing papers in "Psychology and Neuroscience in 2011"

Early life stress, HPA axis, and depression

Abstract: evidence from various studies suggests a preeminent role for early adverse experiences in the development of psychopathology, especially depression. The most recent studies reviewed herein suggest that early life stressors are associated with an increased risk for mood disorders in adulthood. This review examines the emerging literature on the relationship between stress, hypothalamic-pituitary-adrenal (HPA) axis function, and depression and the role of early life stress as an important risk factor for HPA axis dysregulation. The most consistent findings in the literature show increased activity of the HPA axis in depression associated with hypercortisolemia and reduced inhibitory feedback. Moreover, HPA axis changes appear to be state- dependent, tending to improve upon resolution of the depressive syndrome. Interestingly, persistent HPA hyperactivity has been associated with higher rates of relapse. These studies suggest that an evaluation of the HPA axis during antidepressant treatment may help identify patients who are at a higher risk for relapse. These findings suggest that this dysregulation of the HPA axis is partially attributable to an imbalance between glucocorticoid and mineralocorticoid receptors. Evidence has consistently demonstrated that glucocorticoid receptor function is impaired in major depression, but few studies have assessed the activity of mineralocorticoid receptors in depression. Thus, more studies are needed to elucidate this issue. Keywords: early life stress, childhood trauma, depression, treatment-resistant depression, hypothalamic-pituitary-adrenal axis.

Analysis of the occurrence of early life stress in adult psychiatric patients: a systematic review

Abstract: The purpose of the paper was to conduct a systematic review of early life stress and its association with psychiatric disorders in adulthood. The occurrence of early stress has lasting negative consequences on the individual, with psychopathology onset one of the most important consequences. The degree of early life stress is associated with the severity of psychiatric disorders and disability in adulthood. Methodology: We conducted a search of two databases (PubMed and SciELO), limited to the time span 1990-2010, using the following keywords: child abuse, maltreatment, early stress, and psychiatric disorders. Thirty-one papers were selected for this review. Results: We found that the subtypes of early life stress such as emotional and physical neglect and sexual, emotional, and physical abuse have associations with several psychiatric disorders, but the Borderline Personality Disorder and Mood Disorders are more associated with the categories listed. Conclusions: Exposure to adversities in childhood and adolescence is predictive of psychiatric disorders in adulthood. More studies are needed to understand the mechanisms by which early life stress is a risk factor for future psychopathology.

Modulation of nociceptive-like behavior in zebrafish (Danio rerio) by environmental stressors

Abstract: Zebrafish have been demonstrated to react consistently to noxious chemical stimuli and present reliable phenotypes of stress, fear, and anxiety. In this article, we describe the modulation of nociceptive-like responses of zebrafish to fear-, stress-, and anxiety-eliciting situations. Animals were exposed to an alarm substance, confinement stress, or a novel environment before being injected with 1% acetic acid in the tail. The alarm substance and confinement stress reduced the display of erratic movements and tail-beating behavior elicited by acetic acid. The novelty of the environment, in contrast, increased the frequency of tail-beating behavior. The results suggest that descending modulatory control of nociception exists in zebrafish, with apparent fear- and stress-induced analgesia and anxiety-induced hyperalgesia.

Comparative neurophysiology of spatial luminance contrast sensitivity

Abstract: The luminance contrast sensitivity function has been investigated using behavioral and electrophysiological methods in many vertebrate species. Some features are conserved across species as a shape of the function, but other features, such as the contrast sensitivity peak value, spatial frequency contrast sensitivity peak, and visual acuity have changed. Here, we review contrast sensitivity across different classes of vertebrates, with an emphasis on the frequency contrast sensitivity peak and visual acuity. We also correlate the data obtained from the literature to test the power of the association between visual acuity and the spatial frequency of the contrast sensitivity function peak.

The use of the Cambridge Neuropsychological Test Automated Battery (CANTAB) in neuropsychological assessment: application in Brazilian research with control children and adults with neurological disorders

Abstract: Computerized neuropsychological tests can be effective and have many benefits. This paper addresses these issues using the computer-based Cambridge Neuropsychological Test Automated Battery (CANTAB) to assess Brazilian children and adults. Preliminary normative data for Brazilian children obtained in a series of CANTAB subtests are presented together with data from adults (controls) and samples of patients with multiple sclerosis and Duchenne muscular dystrophy. The results obtained in children confirmed the normative values reported for American children (Luciana & Nelson, 2002), indicating high applicability of the CANTAB battery for children in the evaluation of visual memory, working memory, planning, and set shifting. For multiple sclerosis patients, CANTAB revealed differences between the control and multiple sclerosis groups for all subtests employed, including visual memory, working memory, spatial memory, decision making, inhibitory control, and sustained attention. In children with Duchenne muscular dystrophy, the CANTAB tests revealed specific detriments in attention and memory. These results of the application of CANTAB in different patient groups indicate that the battery is appropriate for assessing several central nervous system diseases.

Fear, anxiety and their disorders: past, present and future neural theories

Abstract: This paper reviews the historical development of a two-dimensional (direction x distance (?)) neural model of defense. It begins with Miller's (1944) analysis, and model, of approach, avoidance and conflict; adds Hinde's (1966) ethological perspective and Flynn's (1967) neural model of fear; and then considers Gray's (1967, 1970) work linking barbiturate action to the hippocampus, McNaughton's (1977) extension of this to other classes of anxiolytics, and Gray & McNaughton's (1983) detailed behavioral comparison of anxiolytics and hippocampal lesions. This work led to Gray's (1982) detailed model of the neuropsychology of anxiety. Rapoport's (1989) model of the control of obsession by the cingulate cortex, and Ledoux's (1994) model of the control of both fear and anxiety to the amygdala, suggested a more complex organisation of defense systems. McNaughton (1989) argued that evolutionary function defines an emotion, and Blanchard and Blanchard (1990) argued for its assessment via ethoexperimental analysis. Graeff (1994) then produced a neural model that mapped defensive distance to neural level, treating all anxiety as being at a greater defensive distance than fear. Seeing this, and the treatment of anxiety as due to uncertainty (which is inconsistent with Miller's data), as being unsatisfactory, Gray and McNaughton (2000) and then McNaughton and Corr (2004) developed the two-dimensional model of defensive systems. This model is clearly incomplete at the present time and its links with neuroeconomics, personality, and stress and greater specification of frontal cortical contributions are suggested as directions for future development.

Efficacy of psychoeducation in bipolar patients: systematic review of randomized trials

Abstract: Bipolar disorder is a recurrent and chronic disorder with significant morbidity and mortality. Currently, pharmacological treatment is considered indispensable in bipolar disorder. However, despite advances in this area, treatment remains suboptimal. A large body of research has shown that innumerable psychosocial factors influence the emergence of mood disorders. Therefore, in addition to pharmacological strategies, psychological interventions are increasingly recognized as an essential component in the treatment of bipolar patients. Among the various approaches of psychosocial interventions, psychoeducation (PE) has been one of the most used. Thus, the aim of this review was to evaluate the efficacy of PE in the clinical course, treatment adherence, and psychosocial functioning of bipolar patients by collecting data from controlled trials that used solely PE as a psychosocial approach. A systematic review of the literature was performed in the PubMed and SCOPUS databases, without date limits, using the following keywords: Psychoeducation and Bipolar disorder. We found 13 randomized controlled trials. Psychoeducation significantly improved the clinical course, treatment adherence, and psychosocial functioning of bipolar patients. It also reduced the number of relapses and recurrences per patient and increased the time to depressive, manic, hypomanic, and mixed recurrences. The number and length of hospitalizations per patient were also lower in patients who received PE. Although we found a limited number of randomized controlled trials that evaluated the efficacy of PE in bipolar disorder, the studies showed positive results in reducing relapse rates and improving long-term treatment adherence. Additionally, PE intervention improves the knowledge of the illness for both patients and caregivers to reduce their distress and improve overall social functioning.

Levels of processing: the evolution of a framework

Abstract: Although the levels of processing framework have evolved over its nearly 40 years of existence, the essence of the idea has not changed from the original. The original article published in 1972 suggests that in the encoding stage of a stimulus, there is a series of processing hierarchies ranging from the shallowest level (perceptual processing-the subject initially perceives the physical and sensory characteristics of the stimulus) to the deepest level (semantic processing-related to pattern recognition and extraction of meaning). The depth processing is associated with high levels of retention and long-term memory traces. After extensive research and criticism, the authors added several concepts that aided in a better understanding of levels of processing framework and the items that subjects can recall such as transfer-appropriate processing and robust encoding. However, there are still some gaps in this framework that call for new scientific investigations, ranging from experimental paradigms with lists of words with healthy or pathological conditions subject to neuroimaging studies to confirm, refute or improve the framework. The aim of this article is to review the publications (articles and book chapters) dating from the original article to the present day to better understand the mnemonic process in terms of levels of processing and to highlight some of its contributions.

Relationships between executive functions tasks in late childhood

Abstract: Executive functions (EF) is a general term that refers to cognitive processes designed to organize and adapt human behavior in situations that require planning and decision making, problem solving, initiation and inhibition of actions, and adapting to changes. Among the main components of executive processes, we can emphasize the ability to inhibit and to present cognitive flexibility due to changes. Understanding the relationships among the various components of EF in adults and children has been a focus in the literature. However, these processes are complex and multiple. The present study sought to determine whether correlations exist among performances measured by different tools used to evaluate EF in school-age children. The sample comprised 59 children aged 8 to 12 years attending public schools. Participants were assessed using verbal fluency tasks and narrative discourse with the Montreal Battery of Evaluation of Communication-MAC Battery, random-number generation, the Hayling Test, the Bells Test, and the n-back test. Correlation analyses were performed using Pearson's correlation coefficient. The results suggested a closer relationship among some components of the evaluation of EF, especially among tasks that assess inhibition and cognitive flexibility.

Evolution of the human feeding behavior

Abstract: The main objective of this review is to discuss human feeding behavior based on evolution. With regard to feeding, the human species has undergone various changes during its evolutionary and social history, from the hunting and gathering phase, including the discovery of fire, to modern times, mainly after the implementation of agriculture. These changes exerted a direct influence on feeding habits and behavior and a considerable impact on some aspects of human health. The present review also discusses some of the foods consumed by the human species that are controversial among investigators from an evolutionary perspective.

The neurobiology of posttraumatic stress disorder: dysfunction in the prefrontal-amygdala circuit?

Abstract: Posttraumatic stress disorder (PTSD) is an anxiety disorder that can develop following exposure to a traumatic event, including terrifying or life-threatening situations such as sexual assault or natural disasters. The disorder is characterized by a reaction of intense fear, helplessness, or horror when the individual experiences, testifies about, or is faced with one or more events that involve death, severe wounds, or a threat to one's own or another's physical integrity. One of the most important symptoms of PTSD is the revival of the traumatic event, which has been interpreted as an inability to downregulate negative emotions. Neuroimaging studies that probed the ability to regulate emotions in healthy volunteers have found a pattern characterized by activation of the prefrontal cortex associated with a reduction in amygdala activity. This suggests an inhibitory prefrontal cortex-amygdala circuit that underlies emotional regulation. The hypothesis that increased amygdala activation associated with PTSD results from dysfunction in the inhibitory mechanism exerted by the prefrontal cortex has been the topic of debate. The present review investigates the validity of dysfunction in the prefrontal-amygdala pathway in PTSD. The studies provide evidence that the amygdala and prefrontal cortex exhibit distinct activation patterns in PTSD, thus supporting the model of a dysfunctional circuit. Inconsistencies in the literature may be attributable to distinct PTSD subgroups, different experimental approaches, different contrasts employed in neuroimaging studies, and small sample sizes.

Social cognition and Theory of Mind: controversies and promises for understanding major psychiatric disorders

Abstract: The term "social cognition" generally refers to the mental operations that underlie social interactions including the perception and interpretation of the intentions, dispositions, and behaviors of others and the generation of a response to these behaviors. Social cognition has been considered a valuable and promising field that strives to understand the nature and outcome of major mental disorders. This article discusses the concept of social cognition and its relationship to Theory of Mind (ToM). Theory of Mind in autistic spectrum disorders has been studied since the 1980s, and cognitive impairments in these disorders may be restricted to ToM deficits because other cognitive domains and nonsocial intelligence are preserved. This article addresses the issues of human ontogeny, reviews the main findings from research on schizophrenia and bipolar disorder, and summarizes the tools commonly used in the assessment of these illnesses.

Differentiation of MDMA or 5-MeO-DIPT induced cognitive deficits in rat following adolescent exposure

Abstract: The so-called "club drug" Foxy or Methoxy Foxy (5-Methoxy-N,N-di(iso)propyltryptamine hydrochloride; 5-MeO-DIPT) is a newer drug of abuse that has recently gained in popularity among recreational users as an alternative to MDMA (Ecstasy). While considerable research into the consequences of MDMA use is available, much remains unknown about the neurobiological consequences of 5-MeO-DIPT use. In the present study, beginning at 35 days of age adolescent rats were given repeated injections of 10 mg/kg of 5-MeO-DIPT, MDMA, or a corresponding volume of isotonic saline. Adult animals (135 days old) were trained and tested on a number of tasks designed to assess the impact, if any, and severity of 5-MeO-DIPT and MDMA, on a series of spatial and nonspatial memory tasks. Both the 5-MeO-DIPT- and the MDMA-treated rats were able to master the spatial navigation tests where the task included a single goal location and all groups performed comparably on these phases of training and testing. Conversely, the performance of both groups of the drug-treated rats was markedly inferior to that of the control animals on a task where the goal was moved to a new location and on a response learning task, suggesting a lack of flexibility in adapting their responses to changing task demands. In addition, in a response learning version of a learning set task, 5-MeO-DIPT rats made significantly more working memory errors than MDMA or control rats. Results are discussed in terms of observed alterations in serotonin activity in the forebrain and the consequences of compromised serotoninergic systems on cognitive processes.

Frontal stroke: problem solving, decision making, impulsiveness, and depressive symptoms in men and women

Abstract: The present study compared men and women who suffered a frontal lobe stroke with regard to problem solving, decision making, impulsive behavior and depressive symptoms and also correlated these variables between groups. The sample was composed of 10 males and nine females. The study period was 6 months after the stroke. The following instruments were used: Wisconsin Card Sort Test (WCST), Iowa Gambling Task (IGT), Barrat Impulsiveness Scale (BIS11), and Beck Depression Inventory (BDI). For the exclusion criteria of the sample, the Mini International Psychiatric Interview (M.I.N.I Plus) and Mini Mental Stage Examination (MMSE) were used. To measure functional severity post-stroke, the Rankin Scale was used. The average age was 60.90 ± 8.93 years for males and 60.44 ± 11.57 years for females. In females, total impulsiveness (p = .013) and lack of planning caused by impulsiveness (p = .028) were significantly higher compared with males, assessed by the BIS11. These data indicate that females in the present sample who suffered a chronic frontal lesion were more impulsive and presented more planning difficulties in situations without demanding cognitive processing. These results that show gender differences should be considered when planning psychotherapy and cognitive rehabilitation for patients who present these characteristics.

Panic-like behaviors in Carioca High-and Low-conditioned Freezing rats

Abstract: disorder involves both recurrent unexpected panic attacks and persistent concern about having additional attacks. Electrical stimulation of the dorsal periaqueductal gray (dPAG) is an animal model of both panic attack and panic disorder, whereas contextual fear conditioning represents a model of anticipatory anxiety. Previous research indicated that anxiety has an inhibitory effect on panic attack-like behavior. However, still unclear is the role that anticipatory anxiety plays in panic disorder-like behaviors. This issue was investigated with two lines of animals selectively bred for high (Carioca High-Freezing) and low (Carioca Low-Freezing) freezing in response to contextual cues associated with footshock. The results suggest that although anticipatory anxiety might exert an inhibitory effect on the expression of panic attack, it might also facilitate the pathogenesis of panic disorder. Keywords: breeding lines, dorsal periaqueductal gray, contextual fear conditioning, freezing behavior, escape behavior, panic attack, panic disorder.

Stimulus affective valence reverses spatial compatibility effect

Abstract: In spatial compatibility tasks, the Reaction Time to right-side stimuli is shorter for right key responses (compatible condition) than for left key responses (incompatible condition) and vice-versa for left-side stimuli. Similar results have been found when the stimulus location is not relevant for response selection, such as in the Simon task. The Simon effect is the difference between the reaction times for non-corresponding and corresponding conditions. The Simon effect and its variants may be modulated by using emotional stimuli. However, until now, no work has studied how the affective valence of a stimulus influences spatial compatibility effects along the horizontal dimension. The present study investigated this issue by using small lateralized figures of soccer team players as stimuli. In the experiment, a compatible or incompatible response was chosen according to the team shirt. In one block, for the Favorite team, the volunteers had to press the key on the same side as the stimulus hemifield but the opposite-side key for the Rival team. In the other block, a reverse code had to be used. Fourteen right-handed volunteers were tested. Mean reaction times were subjected to analysis of variance with the following variables: Preference (Favorite/Rival), Hemifield (Left/Right), and Response Key (Left/Right). A three-way interaction was found (F1,13 = 6.60, p = .023), showing that the spatial compatibility effects depended on Preference. The Favorite team player elicited the usual spatial compatibility pattern, but for the Rival team player, the reverse effect was found, with incompatible responses being faster than compatible responses. We propose that this modulation may result from approach/avoidance reactions to the Favorite and Rival teams, respectively. Moreover, we suggest as a corollary that the classic spatial compatibility task is a powerful tool for investigating approach/avoidance effects.

Open field behavior and intra-nucleus accumbens dopamine release in vivo in virgin and lactating rats

Abstract: behavioral, endocrine, and neurochemical implications. This experience causes behavioral and neurochemical changes that involve several brain areas important for the expression of maternal behavior. The present study showed that lactating rats exhibited reduced general locomotor activity in the open field test compared with virgin animals. Our hypothesis was that nucleus accumbens dopamine, which regulates maternal behavior in lactating rats, is also involved in the low expression of maternal locomotion in the open field test observed during the early stages of lactation and reflects decreased motivation. Initially we compared open field behavior in virgin and lactating rats to confirm our previous data. Thus, the in vivo release of dopamine in the nucleus accumbens in virgin and lactating female rats was measured. Perfusate concentrations of extracellular dopamine and its metabolites showed no differences between virgin and lactating rats. Thus, the reduced general activity observed in lactating rats might not be related to intra-nucleus accumbens dopamine control. Keywords: maternal behavior, virgin rats, lactating rats, nucleus accumbens, dopamine.

Psychophysical measurements of luminance and chromatic spatial and temporal contrast sensitivity in Duchenne muscular dystrophy

Abstract: In children with Duchenne muscular dystrophy, color vision losses have been related to dystrophin deletions downstream of exon 30, which affect a dystrophin isoform, Dp260, present in the retina. To further evaluate visual function in DMD children, we measured spatial, temporal, and chromatic red-green and blue-yellow contrast sensitivity in two groups of DMD children with gene deletion downstream and upstream of exon 30. Psychophysical spatial contrast sensitivity was measured for low, middle, and high spatial frequencies with achromatic gratings and for low and middle frequencies with red-green and blue-yellow chromatic gratings. Temporal contrast sensitivity was also measured with achromatic stimuli. A reduction in sensitivity at all spatial luminance contrasts was found for the DMD patients with deletion downstream of exon 30. Similar results were found for temporal luminance contrast sensitivity. Red-green chromatic contrast sensitivity was reduced in DMD children with deletion downstream of exon 30, whereas blue-yellow chromatic contrast sensitivity showed no significant differences. We conclude that visual function is impaired in DMD children. Furthermore, we report a genotype-phenotype relationship because the visual impairment occurred in children with deletion downstream but not upstream of exon 30, affecting the retinal isoform of dystrophin Dp260.

Traumatic brain injury patients: does frontal brain lesion influence basic emotion recognition?

Abstract: Adequate emotion recognition is relevant to individuals' interpersonal communication. Patients with frontal traumatic brain injury (TBI) exhibit a lower response to facial emotional stimuli, influencing social interactions. In this sense, the main goal of the current study was to assess the ability of TBI patients in recognizing basic emotions. Photographs of facial expressions of five basic emotions (happiness, sadness, fear, anger, and surprise) were presented to 32 TBI patients and 41 healthy controls. Emotion recognition was measured by accuracy and reaction time. Overall performance of the TBI group was poorer than control group for emotion recognition, both in terms of accuracy and reaction time. It is suggested that TBI patients show impairment on emotion recognition, and this relation seems to be moderated by the lesion localization.

Influence of scheduled restricted feeding on reentrainment of motor activity rhythm after a 6-h light-dark advance in rats

Abstract: Circadian rhythms are entrained to cyclic environmental cues such as the light-dark cycle and food availability. The suprachiasmatic nucleus of the hypothalamus is the main circadian oscillator in mammals and is entrained primarily by the light-dark cycle, although in some experimental situations food availability can affect its oscillation. Here we tested whether scheduled restricted feeding is capable of influencing the reentrainment of the motor activity rhythm (i.e., a behavioral rhythm controlled by the suprachiasmatic nucleus) to a 6-h phase advance of the light-dark cycle. Rats were housed in a standard 12 h:12 h light-dark cycle for 18 days, and then the time of lights-off was advanced. Rats subjected to scheduled restricted feeding starting on the first day of the light-dark shift showed faster reentrainment of the motor activity rhythm compared with control rats maintained with ad libitum food. The results showed that scheduled feeding effectively accelerates reentrainment of a behavioral circadian rhythm and suggest that the procedure may affect activity in the suprachiasmatic nucleus during the stage of reentrainment to light-dark shifts.

Neuropsychological and neurobiological markers of the preclinical stage of Alzheimer's disease

Abstract: Dementia, especially Alzheimer's disease, has a high prevalence in the elderly population. Therefore, identifying individuals who are at a high risk for early diagnosis is crucial to allow both pharmacological and behavioral therapeutic interventions, which in some cases can delay the progression of dementia. This paper describes neuropsychological and neurobiological markers for the early diagnosis of Alzheimer's disease and presents the main risk factors, including neuropathological, neuroanatomical, neurofunctional, genetic, and neuropsychological. The literature shows that the combination of these markers is the best method for predicting Alzheimer's disease, years before its clinical manifestation. The most prevalent neurobiological and neuropsychological risk factors include (1) senile plaques and neurofibrillary tangles in the medial temporal lobe and cortical regions, (2) low concentrations of Aβ1-42 peptide and high concentrations of total tau protein and phosphorylated tau protein in cerebrospinal fluid, (3) reduced global cerebral volume, increased ventricular volume, and atrophy in the hippocampal formation and entorhinal cortex, (4) global reductions in cerebral metabolism and perfusion in the temporoparietal junction, temporal, parietal, and frontal lobes, hippocampal formation, and posterior cingulate cortex, (5) the presence of the apolipoprotein E e4 allele, and (6) verbal anterograde episodic long-term memory impairment and executive dysfunction. The present review discusses the evidence for markers that identify individuals who are at a high risk of developing Alzheimer's disease and the importance of longitudinal studies in this context.

Psychoanalytic treatment: a neurobiological view

Abstract: a review of several hypotheses concerning the possible neurobiological correlates of the main processes involved in analytic therapy. Attachment theory may represent an interesting link between psychoanalysis and neurobiology. According to Bowlby's conception, interactions with parental figures during infancy lead to the formation of an "internal working model." This determines how the individual will relate with others and cope with stress throughout life. The patterns formed are in many cases pathological. The internal working model is stored as implicit memory, which is expressed independently of consciousness. Clinical improvement in analytic therapy ultimately depends on changes in the implicit memory system, which entails structural brain modifications. Implicit memory system changes may be related to alterations in explicit memory systems, which result from interpretative work. They may also occur directly as a result of the emotional experiences in the patient-analyst relationship.

Cortical representation of the horizon in V1 and peripheral scaling in mammals with lateral eyes

Abstract: present investigation we mapped the primary visual area of the South American diurnal rodent, Dasyprocta aguti, by standardized electrophysiological mapping techniques. In particular, we performed a series of mapping experiments of the visual streak in the primary visual cortex. We found that the representation of the visual streak in V1 is greatly expanded, the nasal 10 degrees of the visual streak representation occupies ten times more cortical area than equivalent areas in the central or temporal representation. Comparison of these data with those on the density of ganglion cells in the retina at corresponding locations in the visual field reveal a significant mismatch between these two variables. The nasal representation is greatly expanded along the horizontal meridian in V1 as compared to the central and temporal regions whereas the density of ganglion cells decreases with progression along the visual streak from central region towards the nasal or temporal visual field. A review of the available data reveals that all lateral-eyed mammals exhibit a similar mismatch between the retinal and cortical representation of the visual field, and this mismatches is greater in those species with well defined visual streaks such as rabbit and agouti. KeyWords: horizontal meridian, V1 map, retinal ganglion cells, lateral-eyed mammals

Prenatal alcohol exposure did not affect impulsivity in rats that performed delay or probability discounting tasks

Abstract: who fall under the spectrum of the Fetal Alcohol Syndrome have a higher prevalence of several cognitive disturbances, including a greater probability of being diagnosed with attention-deficit hyperactivity disorder (ADHD). Some of these effects, such as hyperactivity and attentional impairments, are already well established in the literature. The assessment of impulsive choice, however, has received little attention in human and animal studies. In the present study, we attempted to investigate the effects of prenatal ethanol exposure on two tasks related to impulsive choice that have never been studied in this condition: delay and probability discounting. Method: Rats prenatally exposed to ethanol (liquid diets with 0%, 10%, or 35% ethanol-derived calories (EDC) or laboratory chow) were trained to respond for food in either delay (n = 21) or probability (n = 48) discounting tasks performed in computer-controlled operant conditioning chambers. Results: Prenatal treatment failed to differentiate the rates at which the rats chose the larger reinforcer associated with delay - in a task in which 35% EDC was not tested - or risk, although the results suggest that further tests are warranted. Keywords: delay discounting, probability discounting, Fetal Alcohol Syndrome, prenatal ethanol exposure, impulsivity

On selecting emotional outcomes in a rehabilitation program for persons with traumatic brain injury in Brazil

Abstract: Traumatic brain injury (TBI) is an important health problem in Brazil. It frequently results in a variety of sequelae, including cognitive, behavioral, and physical impairments that are frequently related to difficulties in community reintegration and successful rehabilitation outcomes. The literature shows that several variables are involved in positive outcomes, including neuropsychological deficits, services received, and social support. Brazil has a paucity of rehabilitation programs for persons with TBI. Intervention outcomes are underreported, and culturally adapted rehabilitation strategies are rarely found. The present study describes a rehabilitation program, presents emotional factors as an important outcome, and discusses a case that illustrates the major points debated.

Defense-related emotions in humans

Abstract: The study of the role of serotonin in anxiety has led to the view that this neurotransmitter enhances anxiety, but inhibits panic. Validation of this hypothesis has been made using two experimental procedures that increase anxiety in human volunteers. One is classical conditioning of the skin electrical conductance response, which is assumed to represent anxiety. The other is simulated public speaking, which is believed to mobilize the same neural networks that are operative in panic and social anxiety disorders. In general, the results of these studies have fulfilled the predictions derived from the above hypothesis. The same procedures have been applied to panic disorder patients, and the obtained results have shown that these patients had a blunted anxiety response to public speaking. This speaking stress also did not activate the hypothalamic-pituitary-adrenal axis, which, in contrast, was activated by anticipatory anxiety. It may be concluded that anxiety and panic are qualitatively different emotional states, respectively related to the animal defense reactions to potential and proximal threat. In agreement, reported results of recent neuroimaging studies have shown that anxiety activates prefrontal cortical areas, whereas panic activates midbrain regions, particularly the periaqueductal gray matter. As a general conclusion, it may be said that anxiety, fear and panic do not belong to the same continuum of increasing intensity; instead, they are qualitatively different emotional states.

Contrast sensitivity and retinal ganglion cell responses in the primate

Abstract: Human contrast sensitivity is considered in relation to the responses delivered by retinal ganglion cells of the primate to luminance and chromatic contrast. At different temporal frequencies, response amplitude relative to response variability determines the limit to sensitivity of a single ganglion cell. This can be related to specific models of central detection mechanisms. Both for luminance and chromatic contrast, psychophysical sensitivity to temporal modulation can be achieved by summation of activity of just a few cells that provide input to a detection mechanism. This analysis is then extended to a spatial context. Several sets of data indicate that, in spatial terms, detection mechanisms are of limited spatial extent, and that, at least in the case of luminance patterns, eye movements play a critical role in contrast detection.

Proprioceptive deficits in Parkinson's disease: from clinical data to animal experimentation

Abstract: Parkinson's disease (PD) is characterized by the manifestation of akinesia, slowness to initiate movement, muscle rigidity, and tremors. However, recent evidence indicates that this pathology also causes alterations in proprioception. Disturbances in proprioceptive mechanisms directly affect postural control and the ability to calculate the velocity and amplitude of movement, suggesting that these alterations are related to the motor symptoms of PD. This article reviews the clinical data on these symptoms and presents evidence of a connection between proprioceptive deficits and the physiology of PD. The identification of proprioceptive impairments in different forms of Parkinsonism can provide valuable clues on the physiopathology of proprioception in idiopathic PD.

Binding faces and names in working memory requires additional attentional resources

Abstract: In this study we used the dual-task paradigm to investigate the involvement of attention in the binding of verbal and visual information in working memory. A secondary task, backward counting by threes (BCT), was performed during the retention interval of the primary recognition task based on either visual or verbal information or the binding of both. The BCT affected accuracy and response time. Accuracy was affected only in the binding condition; response time was affected only in the isolated information condition. Together these results suggest that storing integrated visual and verbal information requires more attentional resources than storing information received separately. These results are discussed in terms of involvement of the central executive in storing integrated information in working memory.

Effects of single, brief exposure to an 8 mT electromagnetic field on avoidance learning in male and female mice

Abstract: The present study investigated the effect of extremely low frequency (8 mT, 50 Hz) electromagnetic fields (ELF-EMF) on avoidance learning in mice and compared the effect of an ELF-EMF in adult male and female mice. Learning was evaluated using a passive avoidance learning procedure in a standard wooden box, in which, despite their instinctive tendencies, mice learn to stay on a small platform to avoidant an electric shock. Before each learning session, the animals were exposed to an 8 mT, 50 Hz ELF created by a round coil. Immediately after 60 min exposure to the ELF-EMF, the mice were subjected to avoidance learning. The animals in the sham-exposed control group were placed in the coil for 60 min but were not exposed to the EMF and were subjected to the same behavioral procedures as the experimental group. The comparison of learned behaviors in the experimental and control groups showed that exposure to an 8 mT, 50 Hz ELF for 60 min significantly affected passive avoidance learning in both male (p < .023) and female (p < .015) mice.