Resetting of Auditory and Visual Segregation Occurs After Transient Stimuli of the Same Modality.

In the presence of a continually changing sensory environment, maintaining stable but flexible awareness is paramount, and requires continual organization of information. Determining which stimulus features belong together, and which are separate is therefore one of the primary tasks of the sensory systems. Unknown is whether there is a global or sensory-specific mechanism that regulates the final perceptual outcome of this streaming process. To test the extent of modality independence in perceptual control, an auditory streaming experiment, and a visual moving-plaid experiment were performed. Both were designed to evoke alternating perception of an integrated or segregated percept. In both experiments, transient auditory and visual distractor stimuli were presented in separate blocks, such that the distractors did not overlap in frequency or space with the streaming or plaid stimuli, respectively, thus preventing peripheral interference. When a distractor was presented in the opposite modality as the bistable stimulus (visual distractors during auditory streaming or auditory distractors during visual streaming), the probability of percept switching was not significantly different than when no distractor was presented. Conversely, significant differences in switch probability were observed following within-modality distractors, but only when the pre-distractor percept was segregated. Due to the modality-specificity of the distractor-induced resetting, the results suggest that conscious perception is at least partially controlled by modality-specific processing. The fact that the distractors did not have peripheral overlap with the bistable stimuli indicates that the perceptual reset is due to interference at a locus in which stimuli of different frequencies and spatial locations are integrated.

Individual vulnerability to escalated aggressive behavior by a low dose of alcohol: decreased serotonin receptor mRNA in the prefrontal cortex of male mice.

Low to moderate doses of alcohol consumption induce heightened aggressive behavior in some, but not all individuals. Individual vulnerability for this nonadaptive behavior may be determined by an interaction of genetic and environmental factors with the sensitivity of alcohol's effects on brain and behavior. We used a previously established protocol for alcohol oral self-administration and characterized alcohol-heightened aggressive (AHA) mice as compared with alcohol non-heightened (ANA) counterparts. A week later, we quantified mRNA steady state levels of several candidate genes in the serotonin [5-hydroxytryptamine (5-HT)] system in different brain areas. We report a regionally selective and significant reduction of all 5-HT receptor subtype transcripts, except for 5-HT(3), in the prefrontal cortex of AHA mice. Comparable gene expression profile was previously observed in aggressive mice induced by social isolation or by an anabolic androgenic steroid. Additional change in the 5-HT(1B) receptor transcripts was seen in the amygdala and hypothalamus of AHA mice. In both these areas, 5-HT(1B) mRNA was elevated when compared with ANA mice. In the hypothalamus, AHA mice also showed increased transcripts for 5-HT(2A) receptor. In the midbrain, 5-HT synthetic enzyme, 5-HT transporter and 5-HT receptors mRNA levels were similar between groups. Our results emphasize a role for postsynaptic over presynaptic 5-HT receptors in mice which showed escalated aggression after the consumption of a moderate dose of alcohol. This gene expression profile of 5-HT neurotransmission components in the brain of mice may suggest a vulnerability trait for alcohol-heightened aggression.

Anabolic-androgenic steroid treatment induces behavioral disinhibition and downregulation of serotonin receptor messenger RNA in the prefrontal cortex and amygdala of male mice.

Nandrolone is an anabolic-androgenic steroid (AAS) that is highly abused by individuals seeking enhanced physical strength or body appearance. Supraphysiological doses of this synthetic testosterone derivative have been associated with many physical and psychiatric adverse effects, particularly episodes of impulsiveness and overt aggressive behavior. As the neural mechanisms underlying AAS-induced behavioral disinhibition are unknown, we investigated the status of serotonergic system-related transcripts in several brain areas of mice receiving prolonged nandrolone administration. Male C57BL/6J mice received 15 mg/kg of nandrolone decanoate subcutaneously once daily for 28 days, and different sets of animals were used to investigate motor-related and emotion-related behaviors or 5-HT-related messenger RNA (mRNA) levels by real-time quantitative polymerase chain reaction. AAS-injected mice had increased body weight, were more active and displayed anxious-like behaviors in novel environments. They exhibited reduced immobility in the forced swim test, a higher probability of being aggressive and more readily attacked opponents. AAS treatment substantially reduced mRNA levels of most investigated postsynaptic 5-HT receptors in the amygdala and prefrontal cortex. Interestingly,the 5-HT(1B) mRNA level was further reduced in the hippocampus and hypothalamus. There was no alteration of 5-HT system transcript levels in the midbrain. In conclusion,high doses of AAS nandrolone in male mice recapitulate the behavioral disinhibition observed in abusers. Furthermore, these high doses downregulate 5-HT receptor mRNA levels in the amygdala and prefrontal cortex. Our combined findings suggest these areas as critical sites for AAS-induced effects and a possible role for the 5-HT(1B) receptor in the observed behavioral disinhibition.

Confiabilidade intra e interobservador da análise cinemática angular do quadril durante o teste sentar e alcançar para mensurar o comprimento dos isquiotibiais em estudantes universitários / Intra and interobserver reliability of angular kinematic analysis of the hip joint during the sit-and-reach test to measure hamstring length in university students

CONTEXTUALIZAÇÃO: O teste sentar e alcançar (TSA), utilizado para mensurar flexibilidade da coluna lombar e músculos isquiotibiais (IT), é mais adequado quando realizado concomitante à mensuração do ângulo da articulação do quadril (AAQ). OBJETIVO: Avaliar a confiabilidade intra e interobservadores do TSA na mensuração do comprimento dos IT por meio da análise cinemática angular. MÉTODO: Participaram 50 universitários (X= 21,5 anos; DP= 1,5) sem alterações musculoesqueléticas. Foram utilizados: banco padrão do TSA com porta para avaliar a ação dos gastrocnêmios no TSA e câmera fotográfica digital posicionada sobre um tripé. Marcadores cutâneos foram posicionados na: espinha ilíaca ântero-superior e trocânter maior. Realizaram-se duas aquisições de imagem: uma com porta fechada - PF e outra, aberta - PA. Para testar a confiabilidade intra e interobservadores foram utilizados: coeficiente de correlação intraclasse (CCI) - efeito aleatório com um fator - e teste de concordância de Bland e Altman (d = diferença média entre as medidas) com os respectivos intervalos de confiança de 95 por cento (IC 95 por cento). RESULTADOS: Os testes de confiabilidade intra-observador do AAQ foram: CCIpf = 0,97 - IC95 por cento [0,95;0,99] e Bland e Altman d = -0,02 - IC95 por cento [-0,11;0,07]; CCIpa= 0,98 - IC95 por cento [0,96;0,99], d = -0,01 - IC95 por cento [-0,11;0,08]. Para confiabilidade interobservador: CCIpf =0,96 - IC95 por cento [0,94;0,98] e d = -0,07 - IC95 por cento [-0,19;0,03]; CCIpa=0,96 - IC95 por cento [0,93;0,98] e d = -0,06 - IC95 por cento [-0,19;0,52]. CONCLUSÃO: Os testes intra e interobservador (PF e PA) da avaliação do AAQ, pela análise cinemática, apresentaram alta confiabilidade. A técnica é de fácil aplicação (necessita apenas do banco TSA padrão e câmera fotográfica) e fornece à prática clínica um método confiável para mensurar os IT pela cinemetria.

BACKGROUND: The sit-and-reach test (SRT) is used to measure the flexibility of the lumbar spine and hamstring muscles and is better when the hip joint angle (HJA) is measured concomitantly. OBJECTIVE: To assess the intra and interobserver reliability of the SRT for measuring hamstring muscle length through angular kinematic analysis. METHOD: Fifty university students (X= 21.5 years; SD= 1.5) without musculoskeletal abnormalities took part. A standard SRT bench with a door (to assess the action of the gastrocnemius muscles) and a digital photographic camera positioned on a tripod were used. Skin markers were placed on the anterosuperior iliac spine and greater trochanter. Two images were recorded: one with the door closed (DC) and another with the door open (DO). To test the intra and interobserver reliability, the intraclass correlation coefficient (ICC) (random effect with one factor) and the Bland and Altman concordance test (d= mean difference between measurements) were used, with the respective 95 percent confidence intervals (95 percent CI). RESULTS: The intraobserver reliability of the HJA test was: ICCdc= 0.97 (95 percent CI [0.95;0.99]) and Bland and Altman d = -0.02 (95 percent CI [-0.11;0.07]); ICCdo = 0.98 (95 percent CI [0.96;0.99]), d = -0.01 (95 percent CI [-0.11;0.08]). For the interobserver reliability: ICCdc= 0.96 (95 percent CI [0.94;0.98]) and d = -0.07 (95 percent CI [-0.19;0.03]); ICCdo= 0.96 (95 percent CI [0.93;0.98] and d = -0.06 (95 percent CI [-0.19;0.52]. CONCLUSION: The intra and interobserver reliability tests (DC and DO) for HJA assessment using kinematic analysis showed high reliability. The technique is easy to apply (only requiring a standard SRT bench and a photographic camera) and provides a reliable method for measuring hamstring muscles using kinematic analysis in clinical practice.