Resumo em Inglês:

The handedness recognition of visually perceived body parts engages motor representations that are constrained by the same biomechanical factors that limit the execution of real movements. In the present study, we used small plastic cutouts that represented the human hand to investigate the properties of mental images generated during their haptic exploration. Our working hypothesis was that any handedness recognition task that involves body parts depends on motor imagery. Forty-four blindfolded, right-handed volunteers participated in a handedness evaluation experiment using their index finger to explore either the back or palm view of a haptic stimulus that represented the human hand. The stimuli were presented in four different orientations, and we measured the subjects' response times. Our results showed that stimulus configurations that resemble awkward positions of the human hand are associated with longer response times (p < .006), indicating that the haptic exploration of stimuli that represent body parts also leads to motor imagery that is constrained by biomechanical factors.

Resumo em Inglês:

We studied the influence of attention on the timecourse of Stroop-like conflict. Thirty-two volunteers performed a Stroop matching task in which they had to compare either the color (n = 16) or meaning (n = 16) of two stimuli. The first stimulus was always a color-name printed in yellow, red, or blue (i.e., Stroop stimulus), and the second stimulus was either a color-bar (Experiment 1) or color-word in white ink (Experiment 2). Stimulus onset asynchrony (SOA) was varied parametrically. Interference by incongruent Stroop stimuli was clearly modulated by SOA manipulation in both cases. The results are discussed in terms of interactions between translational and attentional models in which the degree of Stroop-like interference is attributed to time implementation of attentional mechanisms during color-to-color and color-to-word matching contexts.

Resumo em Inglês:

Motor impairment following stroke is a leading cause of disability in adults. Despite advances in motor rehabilitation techniques, many adult stroke survivors never approach full functional recovery. Intriguingly, children exhibit better rehabilitation outcomes when compared to adults suffering from comparable brain injuries, yet the reasons for this remain unclear. A common explanation is that neuroplasticity in adults is substantially limited following stroke, thus constraining the brain's ability to reorganize in response to neurological insult. This explanation, however, does not suffice for there is much evidence suggesting that neuroplasticity in adults is not limited following stroke. We hypothesize that diminished functional recovery in adults is in part due to inhibitory neuronal interactions, such as transcallosal inhibition, that serve to optimize motor performance as the brain matures. Following stroke, these inhibitory interactions pose rigid barriers to recovery by inhibiting activity in the affected regions and hindering recruitment of compensatory pathways. In contrast, children exhibit better rehabilitation outcomes in part because they have not fully developed the inhibitory interactions that impede functional recovery in adults. We suggest that noninvasive brain stimulation can be used in the context of motor rehabilitation following stroke to reduce the effects of existing inhibitory connections, effectively returning the brain to a state that is more amenable to rehabilitation. We conclude by discussing further research to explore this hypothesis and its implications.

Resumo em Inglês:

Bipolar disorder (BD) is a prevalent and highly disabling psychiatric condition. Despite the widely acknowledged importance of psychosocial interventions that involve a complex cognitive, behavioral, and biological process to help patients cope better with their illness, few studies have systematically evaluated coping in BD. Therefore, our objective was to examine recent developments in current research on coping in BD. Several studies have documented a strong association between BD and numerous neuroanatomical and neuropsychological abnormalities, particularly multiple episodes and longer durations of the disorder. The most marked effects of BD encompass brain areas involved in executive function, which may affect the mechanisms underlying an adequate selection of coping strategies. Thus, the ability of individuals to reduce their own stress burden is impaired, increasing vulnerability to stressful life events and negatively affecting the course of BD. Psychosocial interventions that focus on BD should be evaluated for their ability to improve coping abilities, and research on BD should consider neuropsychological impairment and cognitive-behavioral strategies for coping with stress.

Resumo em Inglês:

Neuropsychological diagnosis requires a structure-function correlation model or a "Conceptual Nervous System." The unpredictably variable, widespread, and multifocal nature of pathological changes in multiple sclerosis (MS) challenges the neuropsychological localizationist assumption. To be adapted to MS pathological and clinical heterogeneity, a Conceptual Nervous System should explain impairments associated with multifocal, subcortical, and white matter lesions that cause information processing slowing and working memory/executive function impairment. Our main goal in this theoretical study was to develop a Conceptual Nervous System for MS by integrating current neuropsychological conceptions of structural-functional correlations in MS with a model of conscious mental activity developed by Ernst Pöppel , based on periodic reentrant activity between cortical and subcortical structures. Neuropsychological profiles in MS can be explained by both threshold and multiple disconnection mechanisms. The Conceptual Nervous System encompasses a functional and structural model of the human brain-mind. The functional model classifies mental function into material and formal. Material/semantic functions are modularly organized, and their impairment causes classical focal neuropsychological symptoms. Multiple sclerosis preferentially impairs formal/syntactic function related to widespread patterns of activation and temporal organization. The structural model specifies the system anatomically functions. The neuropsychological adequacy of the proposed Conceptual Nervous System to MS is analyzed by comparing its predictions to results of extant meta-analytic studies.

Resumo em Inglês:

The present study investigated the relationship between posterior fossa tumors (astrocytoma and medulloblastoma) and their respective treatments and cognitive performance in Brazilian children by measuring Intelligence Quotient (IQ). Twenty children were enrolled in the study, of whom 13 were diagnosed with astrocytoma (average age at evaluation, 10.2 years; eight girls and five boys) and seven were diagnosed with medulloblastoma (average age at evaluation, 9.2 years; five girls and two boys). The first subgroup underwent exclusively tumor resection surgery, and the second subgroup underwent surgery, chemotherapy (Vincristine, Cisplatine, and Carmustine), and radiotherapy (total dose, 54 Gy). The inclusion criteria for the clinical group were normal social and emotional behavior before the diagnosis and motor and visual performance not excessively deteriorated after surgery. All participants were submitted to the Wechsler Intelligence Scale for Children - third version, and their scores were related to standard norms established for Brazilian children and compared with regard to the diagnosis subgroups and treatment modalities. Statistically significant differences were identified between the two diagnosis subgroups in Performance IQ and Processing Speed scores. The medulloblastoma subgroup presented poorer performance in all domains compared with the astrocytoma subgroup. Time interval between diagnosis and neuropsychological evaluation also had a significant effect on Processing Speed and Freedom from Distractibility in the medulloblastoma subgroup. These results provide empirical evidence of a possible significant effect of radiotherapy exposure on processing speed and global intellectual capacity.

Resumo em Inglês:

Childhood neuropsychology is a growing scientific area in Brazil. Regarding cognitive function in infancy, executive function (EF) has been the main focus of several studies because of its importance for and complexity in human cognition and behavior. Executive functions can be considered a set of cognitive processes related to control and integration devoted to the execution of goal-directed behaviors. Research has shown that these abilities begin in infancy and progressively develop until adulthood. Although some studies on EF development in children have already been conducted, our knowledge on this topic is still incipient. Because of the relevant role of age in cognition and EF development, the present study investigated whether differences exist between children aged 6 to 12 years concerning their performance on the Hayling test-adult version, an instrument that assesses the EF components of initiation and inhibition. Pilot data are presented that verify the applicability of this test to children. Significant differences were found between comparable age groups only in three of the seven main Hayling test scores, suggesting that the adult version may not be appropriate for children, and an adaptation of the test for child assessment is necessary. The study may lead to an initial reflection on the development of these components and thus contribute to improvements in the field of child neuropsychology.

Resumo em Inglês:

Classical and operant conditioning principles, such as the behavioral discrepancy-derived assumption that reinforcement always selects antecedent stimulus and response relations, have been studied at the neural level, mainly by observing the strengthening of neuronal responses or synaptic connections. A review of the literature on the neural basis of behavior provided extensive scientific data that indicate a synthesis between the two conditioning processes based mainly on stimulus control in learning tasks. The resulting analysis revealed the following aspects. Dopamine acts as a behavioral discrepancy signal in the midbrain pathway of positive reinforcement, leading toward the nucleus accumbens. Dopamine modulates both types of conditioning in the Aplysia mollusk and in mammals. In vivo and in vitro mollusk preparations show convergence of both types of conditioning in the same motor neuron. Frontal cortical neurons are involved in behavioral discrimination in reversal and extinction procedures, and these neurons preferentially deliver glutamate through conditioned stimulus or discriminative stimulus pathways. Discriminative neural responses can reliably precede operant movements and can also be common to stimuli that share complex symbolic relations. The present article discusses convergent and divergent points between conditioning paradigms at the neural level of analysis to advance our knowledge on reinforcement.

Resumo em Inglês:

A "second generation" matching-to-sample procedure that minimizes past sources of artifacts involves (1) successive discrimination between sample stimuli, (2) stimulus displays ranging from four to 16 comparisons, (3) variable stimulus locations to avoid unwanted stimulus-location control, and (4) high accuracy levels (e.g., 90% correct on a 16-choice task in which chance accuracy is 6%). Examples of behavioral engineering with experienced capuchin monkeys included four-choice matching problems with video images of monkeys with substantially above-chance matching in a single session and 90% matching within six sessions. Exclusion performance was demonstrated by interspersing non-identical sample-comparison pairs within a baseline of a nine-comparison identity-matching-to-sample procedure with pictures as stimuli. The test for exclusion presented the newly "mapped" stimulus in a situation in which exclusion was not possible. Degradation of matching between physically non-identical forms occurred while baseline identity accuracy was sustained at high levels, thus confirming that Cebus cf. apella is capable of exclusion. Additionally, exclusion performance when baseline matching relations involved non-identical stimuli was shown.

Resumo em Inglês:

All mammal behaviors and functions exhibit synchronization with environmental rhythms. This is accomplished through an internal mechanism that generates and modulates biological rhythms. The circadian timing system, responsible for this process, is formed by connected neural structures. Pathways receive and transmit environmental cues to the central oscillator, the hypothalamic suprachiasmatic nucleus, which mediates physiological and behavioral alterations. The suprachiasmatic nucleus has three major inputs: the retinohypothalamic tract (a direct projection from the retina), the geniculohypothalamic tract (an indirect photic projection originating in the intergeniculate leaflet), and a dense serotonergic plexus from the raphe nuclei. The serotonergic pathway, a source of non-photic cues to the suprachiasmatic nucleus, modulates its activity. The importance of raphe nuclei in circadian rhythms, especially in photic responses, has been demonstrated in many studies. Serotonin is the raphe neurotransmitter that triggers phase shifts, inhibits light-induced phase-shifts, and plays a role in controlling the sleep-wake cycle. All data to date have demonstrated the importance of the raphe, through serotonergic afferents, in adjusting circadian rhythms and must therefore be considered a component of the circadian timing system. The aim of this paper is to review the literature addressing the involvement of serotonin in the modulation of circadian rhythm.

Resumo em Inglês:

Tardive dyskinesia (TD) is a late-onset side effect mainly affecting the orofacial region of patients treated chronically with classic antipsychotic drugs such as haloperidol (HAL). The causes of TD remain unknown. We hypothesized that faulty synaptic re-organization might be related to TD-like syndromes and used the vacuous chewing movements (VCM) model in rats to investigate the expression of four synaptic proteins, synaptophysin, syntaxin, spinophilin and PSD-95, in brains of HAL-treated rats. Male Sprague-Dawley rats were treated for 14 weeks with either haloperidol decanoate (21 mg/kg once every 3 weeks, I.M) or vehicle and VCMs were monitored on a weekly basis. As expected, VCMs developed reliably and were consistently more pronounced in some rats than in others. Using immunohistochemistry in anatomically preserved brain sections as well as Western Blot analyses of whole cells or synaptosomal fractions in striatal tissue, we found no significant effect of chronic HAL on levels of these proteins. Neither did we find significant differences in the levels of the four synaptic markers when comparing rats showing High vs. Low levels of VCMs. These results suggest that structural synaptic alterations (e.g. involving increased number of synapses) may not be the underlying mechanism of oral dyskinesias induced by chronic antipsychotic drug treatment. The possibility that functional neuroplastic changes occur remains to be investigated.

Resumo em Inglês:

The purpose of the present study was to estimate the protective effects of curcumin against anxiety and memory impairment, which are often comorbid in patients with anxiety disorders who are on standard anxiolytic therapy. The effects of curcumin on brain monoamine levels were also determined. We used the elevated plus maze (EPM), a standard animal model of anxiety, to determine the effects of subacute administration (14 days) of curcumin at doses of 5 and 10 mg/kg (p.o.) against pentylenetetrazole (PTZ; 20 mg/kg, i.p.)-induced anxiety-like behavior, followed by an evaluation of the effects of curcumin on cognitive deficits induced by PTZ using the passive avoidance retention task. Rats were exposed to the passive avoidance learning task before the initiation of treatment, and the effects on memory retention were studied 24 h after the EPM trial. A marked increase in the time spent in the open arms, an index of anxiety, and an increase in the step-down latency, an index of memory retention, were observed in curcumin-treated rats. Curcumin increased the levels of serotonin, norepinephrine, and dopamine in various regions of the rat brain. These results confirm the anxiolytic and memory-retentive effects of curcumin, and alterations in brain monoamine levels may have contributed to the present findings.

Resumo em Inglês:

This study investigated the behavioral effects in the forced swim test (FST) and the elevated plus-maze (EPM) of acute administration of WAY 161503 ([4aR]-8,9-dichloro-2,3,4,4a-tetrahydro-1H-pyrazino[1,2-a]quinoxalin-5[6 H]-one), a selective 5-HT2C receptor agonist with putative antidepressant-like properties. Fifteen minutes after intraperitoneal (i.p.) injections of either WAY 161503 (1, 3 and 10 mg/kg) or saline, naive male Wistar rats were exposed to the EPM for 5 min to assess classical and ethological anxiety-like measures. Immediately after EPM exposure, each animal was exposed to the FST, and the latency to the first episode of immobility was recorded (trial session). Twenty-four hours later, the rats were reexposed to a second EPM-FST exposure sequence (test session for FST) under the effect of the same pharmacological treatment. The two lowest WAY 161503 doses selectively reduced open-arm exploration and increased risk-assessment without affecting locomotor activity. This selective anxiogenic-like effect was observed in both the first and second EPM exposures. The highest WAY 161503 dose produced robust locomotor impairment. In the FST, the same WAY 161503 doses significantly increased the latency to the first immobility in the test session, a behavioral profile that suggests an antidepressant-like action. These results further support the involvement of 5-HT2C receptors in the mediation of anxiety and suggest an intricate relationship between anxiogenic- and antidepressant-like actions.

Resumo em Inglês:

Nepeta cataria (catnip) is a plant used in pet toys and to treat human diseases. Catnip has also been used in the treatment of some depressive disorders. In this paper, we studied the antidepressant, anxiogenic, and motor activity effects of acute and repeated feeding of chow enriched with 10% N. cataria leaves and the acute and repeated administration of apolar and polar extracts of N. cataria leaves in male mice. The results showed that repeated feeding and acute and repeated administration with the apolar extract reduced immobility in the behavioral despair test but did not alter elevated plus maze and open-field parameters. Acute feeding and the acute and repeated administration of the polar extracts of N. cataria leaves did not alter the behavior of mice. These data suggest that N. cataria has antidepressant properties. Moreover, this antidepressant activity was present in the apolar extract.