Resumo em Inglês:

Visual perception and action are strongly linked with parallel processing channels connecting the retina, the lateral geniculate nucleus, and the input layers of the primary visual cortex. Achromatic vision is provided by at least two of such channels formed by the M and P neurons. These cell pathways are similarly organized in primates having different lifestyles, including species that are diurnal, nocturnal, and which exhibit a variety of color vision phenotypes. We describe the M and P cell properties by 3D Gábor functions and their 3D Fourier transform. The M and P cells occupy different loci in the Gábor information diagram or Fourier Space. This separation allows the M and P pathways to transmit visual signals with distinct 6D joint entropy for space, spatial frequency, time, and temporal frequency. By combining the M and P impacts on the cortical neurons beyond V1 input layers, the cortical pathways are able to process aspects of visual stimuli with a better precision than it would be possible using the M or P pathway alone. This performance fulfils the requirements of different behavioral tasks.

Resumo em Inglês:

Significant advances in the understanding of processes involved in face perception have been achieved. This study aims to review the literature of face perception in neurobiological and social contexts. The review focused on the mechanisms of mediation of face perception by neural substrates, and discussed some of the social signals provided by faces. We showed that psychological, neurophysiological and neuroimaging studies have demonstrated that a dedicated neural system for face perception exists in primates, which includes the fusiform face area (FFA), anterior superior temporal sulcus (STS) and anterior inferior temporal gyrus (ITG). But it remains to be understood how the integration of face perception occurs in the neurobiological context and in the social context.

Resumo em Inglês:

The processing of facial identity and emotion in schizophrenia and its relation with these patients' cognitive and social functioning has been extensively studied over the last 25 years. In this paper, the results of 32 studies indexed in the PubMed database and published between 2001 and 2005 are analyzed and synthesized. Following the description of the problem and presentation of current hypotheses, methodological aspects and findings concerning the processing of facial emotion and identity are discussed. The analysis shows that, despite the growing attention dedicated to the theme and the provision of more specific results, the question of dependence/ independence between the two processes - emotion and identity recognition - and between these and the pervasive cognitive deficits found in schizophrenia remains unanswered.

Resumo em Inglês:

The Multiple-Faces Configuration Illusion is observed by staring at a black dot while paying attention to a face in the peripheral visual field (Simas, 2000). Changes of facial expressions, movements, depth (EMF) or different face identities (MF) are observed in this illusion. Forty participants took part in the study: 20 outpatients diagnosed with schizophrenia, and 20 people helping friends or relatives in a hospital clinic. The face-stimulus was placed in a partition stand and participants instructed to describe any visual event occurring during 90 s, one eye at a time. Results showed that 100% of women in the experimental group (EG) reported perceiving events related to MF with the left eye. Significantly fewer women saw these events with the right eye. Also, fewer men in the experimental group and men and women in the control group saw these events with either eye.

Resumo em Inglês:

The visual recognition of body parts activates somato-motor representations in the brain. In the present study, we investigate the influence of the plane in which hand drawings are displayed (Vertical or Horizontal) on mental rotations evoked by a handedness recognition task. Sixteen right-handed volunteers participated in an experiment where the task was to evaluate the handedness of drawings of the human hand presented in different perspectives and orientations while the Manual Reaction Time (MRT) was measured. For eight volunteers, the hand drawings were displayed on a vertical screen monitor, while for the remainder a mirror was employed and the same drawings appeared on the horizontal plan. Our main finding was that there are no differences in MRTs among the drawings displayed vertically or horizontally, with some exceptions. However, the MRTs were longer when the hands in the drawings assumed configurations that were more awkward to perform using real movements. These results show that the implicit movements involved with handedness recognition are mainly dependent on biomechanical constraints for distal (hand), but not proximal (shoulder) movements.

Resumo em Inglês:

To investigate the effects of early visual stimulation on the development of tonus and posture control and of grating visual acuity of preterm infants, eight infants received visual stimulation that induced head motion during the first 6 months of life in weekly sessions. Their performance was compared with that of unstimulated preterm infants of same age (n = 6). Both groups were evaluated in the developmental scale of Gesell and had their grating visual acuity measured by swept visually evoked potentials (sweep-VEP). Visuomotor performance and adoption and maintenance of postures were significantly better for the stimulated group (p < .05) compared to the unstimulated group. There was no statistical difference between the two groups for the development of visual acuity. Visuo-motor and postural development improved with the early visuo-motor stimulation program. The lack of influence of this program in the development of visual acuity may be attributed to differences in the pathways involved in the processing of visual acuity of patterns and in the responses elicited by visuo-motor stimulation.

Resumo em Inglês:

The last few years have seen a growing interest in stem cell research. The media has helped to keep attention to the subject making it as popular as therapeutic cloning. A number of studies highlighted the importance of stem cells as prospective therapy for neurodegenerative conditions. The possibility of successful treatment for such pathologies using stem cells has raised enormous hope. Whilst in some countries biotechnologists have realised the commercial potential of the field, human stem cell research and its clinical applications have constantly been subject of ethical and legal debate. The present review brings an overview of recent aspects of stem cell research for central nervous system disorders, with special attention to Parkinson's and Alzheimer's diseases, cerebral ischemic insult and spinal cord injury. Furthermore, the ethical implications regarding the use of embryonic stem cells as a fundamentally more promising cell type are discussed.

Resumo em Inglês:

This paper aims to present the process of construction and content validity of the Brazilian Brief Neuropsychological Assessment Battery Neupsilin, developed to briefly examine the neuropsychological profile of both clinical and healthy populations. It evaluates time and spatial orientation, attention, perception, memory, arithmetic abilities, language, praxia and executive functions (problem solving and verbal fluency). The process of construction was based on psychometric procedures: 1) construction of a preliminary version of the instrument, founded on clinical and research experience of the three specialists, as well as on research on the literature and on already available instruments; 2) blind judges' analyses: a) an analysis of the importance of the inclusion of each subtest considering the assessed construct and the instrument's goal, b) an analysis of the adequacy of each item regarding the construct; 3) reformulation of the instrument; 4) semantic analysis of the items and brainstorming; 5) final analysis done by three specialist judges; 6) pilot study and final version, and 7) content validity. Modifications were done in each stage of the development of the Neupsilin. It demonstrated adequate content validity, with advantages and limitations.

Resumo em Inglês:

Two models of brain asymmetry in emotional processing were reviewed: the right hemisphere and the valence hypotheses. The first states a dominant role for the right hemisphere in emotional processing, whereas the second assumes that the left hemisphere is dominant for positive emotions and the right hemisphere for negative ones. Different methods, such as the divided visual field technique, have supported both hypotheses. The amygdala and the prefrontal cortex are presented as important structures involved on brain asymmetry in emotional processing. The paper ends pointing out new perspectives for the study of the neural subtrates of different components of emotions.

Resumo em Inglês:

The objective of the present study was to evaluate the interaction of two kinds of external stimuli (long-term tactile stimulation and underwater trauma) on the exploratory behavior of malnourished rats in an elevated plus maze (EPM). The results showed that tactile stimulation partially recovered body weight deficits produced by malnutrition and decreased EPM exploration. Malnutrition increased EPM exploration while underwater trauma decreased it, thus reducing differences between well nourished and malnourished animals. These data show that only one of the two external stimuli (underwater trauma) interacted with diet condition, suggesting that the stress caused by trauma was efficient in decreasing higher EPM exploration, equalizing the response of malnourished animals to that of non-traumatized well-nourished animals.

Resumo em Inglês:

The are few reports on the relationship between elevated plus-maze and effects of maintenance conditions in the days prior to the test. Previously, we have demonstrated that being forcibly in total dark or in light for four days does not alter exploratory behavior in the plus-maze. The present study aimed at recording illumination level preferences in rats using a box with light and dark compartments (or another with two light compartments) and the behavioral effect of this choice on the plus-maze. The rats allowed to express their preference to remain in one particular level of illumination tended to stay initially in the dark compartment and gradually preferred to remain in the light compartment. When tested in the elevated plus-maze there were no effects in comparison to controls kept in commercial cages.

Resumo em Inglês:

Chronic administration of selective serotonin reuptake inhibitors (SSRI) enhances dopaminergic activity. However, the role of enhanced dopaminergic transmission in the therapeutic effects of this kind of antidepressants is still unclear. Drugs producing dopaminergic activation lead to an increment in general activity. Thus, it is reasonable to assume that some of the therapeutic effects of SSRIs are due to dopaminergic enhanced functionality. The forced swim test (FST) is a widely used test in the screening of new compounds with potential antidepressant activity. In this study the effects of pretreatment with low doses of the DA release inductor cocaine and the D2, D3 and D4 antagonist haloperidol were analyzed in the FST on rats submitted to chronic intragastric administration of the SSRI fluoxetine. Our results show that animals treated with fluoxetine and pre-treated with cocaine had significantly higher latencies than saline or haloperidol pre-treated subjects. Among both fluoxetine and saline treated animals, those pre-treated with cocaine had significant lesser immobility time. Haloperidol pre-treated animals had significantly higher immobility time than those pre-treated with saline. From these results, it is clear that the pharmacological modification of dopaminergic systems leads to behavioral changes in rats treated with both saline and fluoxetine. The FST does not have enough precision as to distinguish between dopaminergic and nondopaminergic components in the antidepressant effects of SSRIs, for this reason the use of the FST in combination to other models is mandatory.

Resumo em Inglês:

This study investigated the effects of two selective serotonin2C (5-hydroxytryptamine, 5-HT2C) receptor-acting compounds into the ventral hippocampus (VH) of rats exposed to the elevated plus-maze (EPM). In the first experiment, rats were exposed to the EPM 10 min following VH infusions of either vehicle or the selective 5-HT2C-receptor agonist RO-60-0175 (0.3, 1.0, 3.0 and 10.0µg). In addition to conventional parameters of open arm exploration (i.e. percentages of open arm entries and of time spent in these arms), risk assessmentrelated behaviors were recorded as anxiety-like measures in EPM scoring. RO-60-0175 selectively decreased open arm exploration at the dose of 1.0 µg, while inducing locomotor-suppressant effects at the two highest doses. In the second experiment, VH infusions of the selective 5-HT2C antagonist RS 102221 (0.75, 1.25 and 2.5 µg) did not affect open arm exploration, while reducing risk assessment in the closed ones. This behavioral profile of risk assessment is suggestive of an anxiolytic-like action. These results further corroborate our previous findings showing that VH 5-HT2C receptor activation elicits anxiogenic-like and locomotor-suppressant effects, and suggest that the selective blockade of this receptor is accompanied by an anxiolytic-like action as detected by ethologically derived measures in the EPM.