How does negative emotion cause false memories?

Remembering negative events can stimulate high levels of false memory, relative to remembering neutral events. In experiments in which the emotional valence of encoded materials was manipulated with their arousal levels controlled, valence produced a continuum of memory falsification. Falsification was highest for negative materials, intermediate for neutral materials, and lowest for positive materials. Conjoint-recognition analysis produced a simple process-level explanation: As one progresses from positive to neutral to negative valence, false memory increases because (a) the perceived meaning resemblance between false and true items increases and (b) subjects are less able to use verbatim memories of true items to suppress errors.     

Systemic administration of a nitric oxide synthase inhibitor impairs fear sensitization in the plus-maze

The aim of the present study was to evaluate the occurrence of fear sensitization in rats previously treated with an inhibitor of the NO syntheses and submitted to Trial1/Trial2 plus-maze (PM) procedure. Male Wistar rats received a systemic treatment with N(omega)-nitro-L-Arginine-methyl ester (L-NAME; 5, 10 or 50 mg kg(-1)) and were submitted to PM Trial1. In the following day the animals were re-exposed to the PM with no drug administration (Trial2). Some standards spatial-temporal measures, such as the percentage of entries (% Open arm entries) and time spent (% Open arm time) in the open arms and risk assessment frequency were recorded and used to estimate the animal level of fear sensitization in PM Trial2. The results showed that animals receiving L-NAME (50 mg kg(-1)) displayed increased % Open arm entries and % Open arm time in Trial2 in relation to the group receiving 0.9% saline, which is compatible with impaired fear/anxiety acquisition during Trial1/Trial2 PM procedure. In addition, rats treated with L-NAME (50 mg kg(-1)) exhibited low level of risk assessment in Trial2 in relation to the group treated with 0.9% saline, which indicates low level of fear/anxiety during PM re-exposure. The number of entries into the enclosed arms was not changed by any L-NAME treatment, which suggests no bias of the drug treatments on animal locomotor activity. The data suggest that NO synthesis may mediate the fear sensitization process in the PM.     

CONCURRENT RESURGENCE AND BEHAVIORAL HISTORY

The contribution of past experiences to concurrent resurgence was investigated in three experiments. In Experiment 1, resurgence was related to the length of reinforcement history as well as the reinforcement schedule that previously maintained responding. Specifically, more resurgence occurred when key pecks had been reinforced on a variable-interval 1-min schedule than a variable-interval 6-min schedule, but this effect may have been due either to the differential reinforcement rates or differential response rates under the two schedules. When reinforcement rates were similar (Experiment 2), there was more resurgence of high-rate than low-rate responding. When response rates were similar (Experiment 3), resurgence was not related systematically to prior reinforcement rates. Taken together, these three experimental tests of concurrent resurgence illustrate that prior response rates are better predictors of resurgence than are prior reinforcement rates.     

The Quality of Home Environment in Brazil: An Ecological Model

Based on Bronfenbrenner's (1999) ecological perspective, a longitudinal, prospective model of individual differences in the quality of home environment (Home Observation for Measurement of the Environment—HOME) was tested in a sample of 179 Brazilian children and their families. Perinatal measures of family socioeconomic status (SES) and child birth weight had direct effects on HOME at preschool age. As either family SES or child birth weight increased, HOME also increased through diminished emotional distress in the mother a month following childbirth. SES had a negative effect on number of children in the household, which in turn had a long-term negative impact on HOME. Compared to mothers who had reported not to plan their pregnancy, those who did were more likely to have fewer children, to report more spouse support during childbearing, and to show less emotional distress a month after childbirth, all of which also influenced HOME at preschool age. These findings are discussed in light of the broader socio-ecological Brazilian context, with direct implications to clinical practice aimed at improving the quality of home environment.     

Clinical Characterization and Risk Profile of Individuals Seeking Genetic Counseling for Hereditary Breast Cancer in Brazil

Hereditary breast cancer (HBC) accounts for 5–10% of breast cancer cases and it significantly increases the lifetime risk of cancer. Our objective was to evaluate the sociodemographic variables, family history of cancer, breast cancer (BC) screening practices and the risk profile of cancer affected or asymptomatic at-risk women that undergo genetic counseling for hereditary breast cancer in public Brazilian cancer genetics services. Estimated lifetime risk of BC was calculated for asymptomatic women using the Gail and Claus models. The majority of women showed a moderate lifetime risk of developing BC, with an average risk of 19.7% and 19.9% by the Gail and Claus models, respectively. The average prior probability of carrying a BRCA1/2 gene mutation was 16.7% and overall only 32% fulfilled criteria for a hereditary breast cancer syndrome as assessed by family history. We conclude that a significant number of individuals at high-risk for HBC syndromes may not have access to the benefits of cancer genetic counseling in these centers. Contributing factors may include insufficient training of healthcare professionals, disinformation of cancer patients; difficult access to genetic testing and/or resistance in seeking such services. The identification and understanding of these barriers is essential to develop specific strategies to effectively achieve cancer risk reduction in this and other countries were clinical cancer genetics is not yet fully established.     

Undecidability,incompleteness and Arnol'd problems

We present some recent technical results of us on the incompleteness of classical analysis and then discuss our work on the Arnol'd decision problems for the stability of fixed points of dynamical systems.Partially supported by FAPESP and CNP_q (Brazil, Philosophy Section).     

Defense reaction elicited by microinjection of kainic acid into the medial hypothalamus of the rat: antagonism by a GABAA receptor agonist.

Electrical stimulation of either the midbrain central gray or the medial hypothalamus induces a defense reaction in the rat, characterized mainly by increased locomotion, rearing, and leaping. However, microinjection of the excitatory amino acid glutamate was effective only in the former region. Because excitatory amino acids do not depolarize axons of passage, it was suggested that the hypothalamus is devoid of soma/dendrites of neurons commanding the defense reaction. In the present study, we show that a subtoxic dose (60 pmol) of another excitatory amino acid, kainic acid, injected into the medial hypothalamus significantly enhanced locomotion and rearing of Wistar rats systematically observed in an open field. Similar behavioral changes have been reported following microinjection of drugs impairing GABAergic neurotransmission. Local pretreatment with the GABAA receptor agonist THIP (2 nmol) blocked the effect of kainic acid. Therefore, the medial hypothalamus of the rat seems to contain a population of neuronal cell bodies commanding the defense reaction, which is activated by excitatory amino acids and tonically inhibited by GABAergic fibers.     

Dichotic listening in the recovery of aphasia after stroke

Three different dichotic listening tests were given to a group of aphasic patients at various stages of the recovery process. Results were different for each test and in the course of time fluent aphasics demonstrated a tendency to increase right ear preference while nonfluent aphasics showed an increase of left ear preference in the test of dichotic words. The importance of these findings to the understanding of recovery of function is discussed in terms of the role played by the right hemisphere.