Resumo em Inglês:

A growing interest in cognition in aging has been observed because of both the epidemiologic factor of an increase in the lifespan of the world's population and the cognitive changes behaviorally and biologically detectable in this population. The most complex of language components and fundamental in social interaction, discourse production and comprehension are among the most scarcely explored cognitive functions in this context. This review presents and discusses discourse processing in healthy aging with regard to theoretical, behavioral, and neuroimaging evidence. Cognitive and neurobiological models are reviewed, such as the Hemispheric Asymmetry Reduction in Older Adults (HAROLD) model and the Posterior-Anterior Shift in Aging (PASA) model. Among the neuropsycholinguistic research developed to characterize discourse processing in aging individuals, which has contributed to the prevention and treatment of language impairment and the maintenance of communicative competence in aging, studies on the relationship between discourse and working memory, attention, and some executive components are discussed. Regarding neuroimaging data, very few studies that have included cognitive tasks and discourse stimuli were found. Such studies suggest that discourse processing requires not only the participation of both brain hemispheres, but also a more prominent activation of frontal regions. Considering the great complexity and usefulness of discourse in elderly adults' daily communication and the emergence of cognitive deficits related to aging in complex information processing, the necessity of further behavioral and neuroimaging studies, including discourse processing tasks, comparing tasks involving executive, attentional, and mnemonic demands becomes evident.

Resumo em Inglês:

The study compared the brain activation patterns associated with the comprehension of written and spoken Portuguese sentences. An fMRI study measured brain activity while participants read and listened to sentences about general world knowledge. Participants had to decide if the sentences were true or false. To mirror the transient nature of spoken sentences, visual input was presented in rapid serial visual presentation format. The results showed a common core of amodal left inferior frontal and middle temporal gyri activation, as well as modality specific brain activation associated with listening and reading comprehension. Reading comprehension was associated with more left-lateralized activation and with left inferior occipital cortex (including fusiform gyrus) activation. Listening comprehension was associated with extensive bilateral temporal cortex activation and more overall activation of the whole cortex. Results also showed individual differences in brain activation for reading comprehension. Readers with lower working memory capacity showed more activation of right-hemisphere areas (spillover of activation) and more activation in the prefrontal cortex, potentially associated with more demand placed on executive control processes. Readers with higher working memory capacity showed more activation in a frontal-posterior network of areas (left angular and precentral gyri, and right inferior frontal gyrus). The activation of this network may be associated with phonological rehearsal of linguistic information when reading text presented in rapid serial visual format. The study demonstrates the modality fi ngerprints for language comprehension and indicates how low- and high working memory capacity readers deal with reading text presented in serial format.

Resumo em Inglês:

The aim of this study was to identify which neural substrates are engaged during manual Stroop task performance and compare the activation between 8 late proficient Macedonian-English bilinguals and 10 matched English monolinguals. During functional magnetic resonance imaging (fMRI) adult participants performed four Stroop task conditions in a block design (control, congruent, semantically incongruent, response incongruent). Here, we focussed on differences in activation between the two groups in two contrasts: (1) the presence of task-irrelevant information that conflicts at both the response and semantic level (response incongruent versus congruent); and (2) the presence of competing task-relevant information that confl icts at the response level only (response incongruent versus semantically incongruent). For the first contrast, comparisons between monolinguals (English) and the first language of bilinguals (Macedonian) revealed greater activation in the posterior regions of monolinguals, possibly indicative of a more elaborate stimulus evaluation process. For the second contrast, bilinguals showed less activation in anterior cingulate and prefrontal regions than monolinguals. As poor performance on the Stroop task has been found to be associated with greater activation in these two regions, we interpret this in light of earlier ideas regarding cognitive control and the advantages of bilingualism. That is, less effortful word-form processing might indicate that bilinguals are more effectively dealing with response conflict. Together the current findings suggest that learning two languages may modify the neural substrates engaged during tasks that rely on executive functioning.

Resumo em Inglês:

Much of the recent research on discourse comprehension has centered on the readers' ability to construct coherent mental representations of texts. In order to form a unified representation of a given text, a reader must be able to join the information presented in the text with his/her background knowledge to construe the meaning that may not be explicitly stated, through the generation of inferences. In this study, the process of inference making by native speakers of English while reading two different types of text was investigated using electroencephalography (EEG). Subjects read narrative and expository paragraphs, and judged the plausibility of the final sentence of each four-sentence long paragraph by reference to the previous information. The analysis of data focused on the N400 component and on accuracy of behavioral responses. N400 amplitudes revealed that exposition was more demanding than narration in terms of semantic processing, whereas the behavioral data showed that subjects were more prone to generate inferences when reading exposition. Overall, this study suggests that these two types of text are processed differently by the brain, as revealed by the changes in the N400 component across the last sentences of the paragraphs.

Resumo em Inglês:

This article reports an investigation on the cognitive and linguistic mechanisms involved in knowledge management during discourse production of individuals with Alzheimer disease (AD). Two discourse variables were examined, incomplete propositions and repeated propositions. Differences between controls and participants with AD were found concerning the presence of incomplete propositions in a non-informative prompted task. Findings obtained with the informative prompted task suggested that knowledge management was more preserved in the early stage than in the later stage of AD. The majority of the neuropsychological data obtained in this study correlated with the presence of incomplete propositions. The discussion debated on whether this discourse deficit can be attributed to an impaired ability to manage knowledge provided in the context of communication.

Resumo em Inglês:

The classification of aphasic patients' symptoms into a syndrome is a crucial procedure that favours and simplifies the communication among the clinicians involved in patient treatment and follow-up. Nevertheless, the aphasic population usually presents a very heterogeneous symptomatology; consequently, classical syndromes do not offer a good basis to plan their rehabilitation relying on their specific language impairments. Current rehabilitation strategies frequently require the identification of specific cognitive abilities affected. This is why it is common in clinical practice to assess aphasic patients with a syndromic protocol in order to classify them as well as a cognitive battery to plan their rehabilitation. The aim of the present article is to present a quick and reliable tool (i.e., a syndromic classification sheet) to help clinicians classify their clients' symptomatology in a syndrome by means of only one cognitive neuropsychological assessment. Two groups of speech therapists (5 experienced and 5 inexperienced) were asked to classify 5 aphasic patients from a syndromic classification sheet and their assessment protocols. Results indicate an acceptable inter-rater agreement for the experienced group but not for the inexperienced one. In conclusion, the classification sheet turned out to be a useful and reliable tool to classify aphasic patients in a given syndrome and by means of only some subtests from a cognitive assessment battery, provided that clinicians had some years of experience. In addition, this new instrument enables language clinicians to shorten the assessment of their aphasic clients.

Resumo em Inglês:

We introduce a new VEP paradigm - the Jitter Spatial Frequency (JSF) Sweep VEP - that permits efficient mapping of the spatiotemporal tuning of the developmental motion asymmetry (DMA). Vertical sinewave gratings undergoing 90º horizontal oscillatory displacements (6 or 10 Hz) were presented while their SF was swept over 2 to 5 octaves during each VEP trial. JSF sweep VEPs were recorded from 28 infants (8-43 weeks), and symmetric (second-harmonic, F2) and asymmetric (F1) components of the VEP were measured. JSF sweeps can provide four useful estimates: (1,2) the high-SF cutoff of F1 and F2 responses estimates the spatial resolution of direction-selective (DS) and non-DS mechanisms, respectively; (3) the low-SF cutoff for F1 estimate the SF-boundary between mature (F1 absent) and immature (F1 present) DS mechanisms; and (4) the F1 high-SF cutoff estimates the lower velocity limit of cortical DS cells. For 6 Hz, the low-SF F1 cutoffs increased two times faster than traditional (contrast-reversal) VEP grating acuity (0.5 vs ~0.25 octaves/month), and twice that of the high-SF F1 and F2 cutoffs. This implies that no single mechanism can account for the DMA at both low and high SFs. At 10 Hz, the DMA exhibited no significant development, consistent with slower maturation of DS mechanisms at higher ST frequencies. The F2 high-SF cutoffs were higher than F1 at both 6 and 10 Hz, suggesting higher spatial resolution for non-DS (pattern) vs DS (motion) mechanisms. Finally, the lower velocity limit of the DS mechanisms decreased from ~2 deg/sec at 8 weeks, to 0.75 deg/sec at 33 weeks, similar to analogous limits for direction-of-motion identification in adults (~0.5 - 1 deg/sec), and close to prior VEP estimates in infants (0.6 deg/sec).

Resumo em Inglês:

We used psychophysical tests to evaluate spatial vision in 15 subjects with a clinical history of chronic alcoholism by measuring luminance contrast sensitivity and color discrimination. The subjects were initially subjected to clinical inquiry and ophthalmological exam. Subjects then performed psychophysical tests to measure spatial contrast thresholds using sine wave gratings of different spatial frequencies and contrasts and chromatic discrimination thresholds using the Mollon-Reffin test. For the analysis, subjects were divided into three groups according to age and compared with age-matched controls. Ten subjects had some degree of color vision loss, which was quite severe in seven cases. All subjects had normal luminance contrast sensitivity. The results suggest that color vision changes related to chronic alcoholism can occur in the absence of impairment of spatial luminance contrast sensitivity and thus is an important aspect to be considered in the clinical evaluation of this condition.

Resumo em Inglês:

Changes in cortical thickness can be related to neuropsychiatric disorders and neurodegenerative processes. Previous studies have been conducted to characterize the pattern of changes in cortical thickness in several psychiatric diseases. The aim of the present study was to evaluate changes in cortical thickness with magnetic resonance imaging (MRI) in patients with bipolar disorder. Twenty-seven patients with bipolar disorder (14 male, 36.0 ± 16.2 years old; 13 female, 41.6 ± 10.7 years old) and 40 healthy controls (16 male, 36.0 ± 10.5 years old; 24 female, 37.0 ± 4.7 years old) underwent 3T MRI. Sagittal T1-weighted magnetization prepared rapid acquisition gradient echo images were acquired (voxel size, 1.33 mm³; 128 slices; in-plane matrix resolution, 256 × 256; flip angle, 7º; repetition time, 2530 ms; echo time, 3.39 ms; inversion time, 1100 ms). Cortical segmentation was performed using FreeSurfer 4.0.5. The results indicated both thinning and thickening of the cerebral cortex in patients with bipolar disorder compared with controls, depending on gender. Significant (p < .01) thickening was observed in the right hemisphere superior-parietal cortex in female patients with bipolar disorder, and significant (p < .05) thinning was observed in the left hemisphere caudal-anterior cingulate in male patients with bipolar disorder. The other regions did not show significant differences. The results suggest that an analysis of cortical thickness with MRI in patients with bipolar disorder may allow identification of areas that may be morphologically changed compared with controls. Demonstration of these alterations will elucidate the pathophysiology of bipolar disorder and may contribute to better therapies for this disorder.

Resumo em Inglês:

Executive functions (EF) are a group of high-level cognitive processes that control and direct lower-level abilities in order to produce goal-directed behavior. Because these functions are a multidimensional entity, they can be assessed using different tests. One of the tests often used to evaluate EF is the Wisconsin Card Sorting Test (WCST). The WCST is a task that involves hypothesis testing, identification of concepts, resistance to interference, switching categories, and inhibition. Two versions of the task have been used in neuropsychological testing, but little is known about their equivalence. In this study, we investigated the performance of two groups of elderly people in two versions of the task: manual (cards) and computer-based. Fifty-four healthy elderly participants took part in this study; half of the sample was assessed with the computer-based version of the WCST, while the other half performed the manual version. There were no differences between the two versions of the task in our sample of elderly participants (total number correct, perseverative errors, percent conceptual level responses, and number of categories completed). In this sense, the results provide evidence for the equivalence of both versions in the assessment of EF in healthy elderly participants.

Resumo em Inglês:

The Trail Making Test (TMT) has been a useful tool for neuropsychological assessment. The present study analyzed the influence of age and education level on TMT performance in healthy adult Portuguese speakers. The criteria for exclusion were a history of neurological disease, psychiatric illness, substance abuse, learning disabilities, or any other difficulty that may interfere with testing. The sample (n = 318) was divided into four age groups: (i) very young (n = 92; 18-34 years old), (ii) young (n = 66; 35-49 years old), (iii) middle-age (n = 117; 50-64 years old), and (iv) elderly (n = 43; 65-81 years old). The sample was also divided into three education levels: (i) low (2-8 years), (ii) middle (9-11 years), and (iii) high (> 12 years). Correlations among the demographic variables and scores on Trails A and B showed that age and education level were the two variables that most affected TMT scores (p < 0.001, analysis of covariance). Post hoc analyses of age did not reveal significant differences between the middle-age and elderly groups in TMT-A performance or between middle and high education level in TMT-A or TMT-B performance. These results are consistent with previous studies and demonstrate that age and education level affect the performance of Brazilian subjects on the TMT.

Resumo em Inglês:

Knowledge is currently scarce about what happens in the brain when a decision is made to make a donation. This intriguing donation behavior is often assumed to relate to social relationships. The present study used simulated situations in which participants had to decide how to manage money when possibilities for donation were available. Electroencephalographic signals were recorded while participants were exposed to two cognitive situations, the Dictator's Game and the Prisoner's Dilemma, to simulate money exchange between people. Brain activity was measured to determine whether correlations could be made with decisions to donate. Sixty volunteers were assessed, and stimuli were presented randomly. After the presentation of the cognitive tests, the participants were allocated to two groups for the respective cognitive situations. The data showed significant differences in the left prefrontal cortex between questions with a donation context and questions not related to donations. Participants who heard a question related to donation had higher activation in the left prefrontal cortex. These results are consistent with recent functional magnetic resonance imaging studies, suggesting that greater activation in the prefrontal cortex could be produced by the logical evaluation of dilemmas. These results suggest that logical evaluation occurs when faced with a reasonable donation situation.

Resumo em Inglês:

Literature has shown that failures in the ability to down-regulate negative emotions are the core substrate of anxiety disorders. Previous studies have investigated this issue by encouraging individuals to voluntarily change how they think about a situation in order to decrease its emotional impact. The majority of studies has demonstrated that explicit instructions to reduce negative affect in anxious individuals are usually ineffective. Thus, the goal of the present study was to investigate whether an implicit regulation strategy would modulate electrophysiological activity (Late Positive Potential) associated to affective picture viewing. The Late Positive Potential (LPP) is a sustained positive deflection in the event-related potential that is larger following the presentation of emotional compared to neutral visual stimuli. Participants (low trait anxious - LTA and high trait anxious - HTA individuals) performed an attention task (bar orientation discrimination) while emotional distractive pictures were presented. The task was performed in two different contexts: in the Real context, participants were informed that the distractive pictures had been obtained from real life situations, whereas in the Fictitious context they were told that the pictures had been obtained from movie scenes. In this vein, we encouraged participants to change how they appraised the pictures. Results showed that HTA individuals exhibited larger Late Positive Potential (LPPs) when mutilation pictures were presented in the Real context. Importantly, during the Fictitious one (regulation strategy) the LPP was reduced even in HTA individuals, emphasizing its importance to psychotherapeutic interventions. The present results indicate that HTA individuals are susceptible to modifications in affective contexts.

Resumo em Inglês:

Strain and sex differences in fear conditioning were investigated in two commonly used laboratory rats: Sprague Dawleys and Long-Evans. Twenty-two kHz ultrasonic vocalization (USV) distress calls and freezing behavior were used to measure fear responses to contextual and auditory conditioned stimuli (CSs), which were previously paired with a footshock unconditioned stimulus (US). Both strain and sex had significant effects on USVs and freezing during training and subsequent context and tone tests. Overall, the male Sprague Dawley rats froze and emitted USVs more than the other groups. Additionally, levels of freezing and USVs were differentially influenced by the type of CS (context or tone). These results suggest that species-specific defense responses in laboratory rats are highly influenced by the strain and sex of the subject, and that these factors should be considered in future fear conditioning studies.

Resumo em Inglês:

In order to determine the modulation of anxiolytic and panicolytic-like effects of diazepam by the hormonal cycle of female rats, male and female rats - the latter divided per estrous cycle phase (estrus, diestrus, metaestrus and proestrus) - were tested in the elevated T-maze, a behavioral model of panic and anxiety. Diazepam (0.5, 1.0 and 2.0 mg/kg) or saline solution was injected in individual animals that were submitted to one session in the elevated T-maze 25 min after drug/saline administration. The test consisted of three avoidance trials and one escape trial, separated by a 30 s interval, during which the animals were isolated in individual cages. The avoidance trials began with the animal being placed at the end of the maze's enclosed arm. The time necessary for the animal to leave the central square was considered as the response's latency. The trials that exceeded 300 s were considered as failures. Results demonstrate a decrease in the effects of diazepam in inhibitory avoidance (anxiety) trials in females in diestrus and proestrus, but no relation of gender or estrous cycle on diazepam effects on escape trials (fear). The results support the hypothesis that down-regulation of GABA A receptors by activation of nuclear estrogen receptors and induction of PKC-mediated GABA A receptor phosphorylation by activation of surface estrogen receptors in raphe neurons underlie the modulation of diazepam sensitivity by estrogen.

Resumo em Inglês:

The enhanced availability of tryptophan in the brain, as a consequence of exogenous tryptophan administration, can increase neuronal serotonin synthesis and this can interfere with brain function. REM sleep deprivation (D) constitutes another external factor that can change brain excitability, facilitating, in some cases, the manifestation of neurological diseases like epilepsy. Here we used cortical spreading depression (CSD) as a neurophysiological parameter to investigate the effects of a single L-tryptophan intraperitoneal injection combined or not with 72h D-condition (water-tank technique) in rats. A 1h baseline CSD-recording was performed under urethane+chloralose (1g/kg + 40mg/kg) anesthesia and revealed increased CSD propagation velocities in D rats, as compared with non-deprived (ND), or pseudo-deprived (Pseudo) controls. After the baseline CSD recording, L-tryptophan was immediately injected (125 mg/kg ip, dissolved in water at pH about 3) and this was followed by a significant decrease of CSD propagation velocities, as compared to the baseline values in the same animals of the Pseudo, ND and D condition. In an additional control group (ND rats injected with the vehicle), no CSD propagation change was seen. Our findings indicate an important acute antagonistic influence of tryptophan on CSD propagation, which is not affected by REM sleep deprivation. We suggest that this tryptophan effect may be due to a serotonin-mediated action, probably caused by increased serotonin synthesis as a consequence of enhanced tryptophan availability in the brain.