CONSCIÊNCIA E EMOÇÃO: O EFEITO DO PRIMING AFETIVO SUBLIMINAR EM TAREFAS DE ATENÇÃO

Esta tese revisou duas linhas de pesquisa, desenvolvidas nas últimas décadas: o estudo de efeitos de estimulação subliminar priming , e de desencadeamento de reações emocionais por estímulos controlados. Este estudo tem o objetivo de combinar tais linhas para o estudo da consciência com pré-preparo afetivo: efeito de estímulos de conteúdo aversivo, subliminares e supraliminares, sobre a cognição, pela análise do desempenho em tarefa de atenção. Três tarefas experimentais foram realizadas por 35 indivíduos em laboratório de neuropsicologia: a tarefa base onde testamos à detecção de alvo visual simples, e a mesma tarefa de base, porém com estímulos distratores aversivos intercalados, de forma supraliminar ou subliminar (500 ms ou 50 ms de duração), em blocos aleatorizados entre os indivíduos. Calcularam-se índices de detectabilidade e critério de resposta, que serviram para a comparação estatística entre condições (medidas repetidas). Os resultados mostram uma mudança significativa do índice critério , indicando mudança de estratégia na presença de distratores subliminares aversivos. Concluiu-se que a tarefa subliminar fez um efeito destruidor ou devastador na tarefa supraliminar, cometendo menos falso-alarmes protegendo a tarefa supraliminar, tendo um efeito protetor . Os resultados são discutidos no contexto da relevância de influências emocionais sobre o comportamento para a Psicologia da Saúde.

Visual stimuli induce waves of electrical activity in turtle cortex

The computations involved in the processing of a visual scene invariably involve the interactions among neurons throughout all of visual cortex. One hypothesis is that the timing of neuronal activity, as well as the amplitude of activity, provides a means to encode features of objects. The experimental data from studies on cat [Gray, C. M., Konig, P., Engel, A. K. & Singer, W. (1989) Nature (London) 338, 334–337] support a view in which only synchronous (no phase lags) activity carries information about the visual scene. In contrast, theoretical studies suggest, on the one hand, the utility of multiple phases within a population of neurons as a means to encode independent visual features and, on the other hand, the likely existence of timing differences solely on the basis of network dynamics. Here we use widefield imaging in conjunction with voltage-sensitive dyes to record electrical activity from the virtually intact, unanesthetized turtle brain. Our data consist of single-trial measurements. We analyze our data in the frequency domain to isolate coherent events that lie in different frequency bands. Low frequency oscillations (<5 Hz) are seen in both ongoing activity and activity induced by visual stimuli. These oscillations propagate parallel to the afferent input. Higher frequency activity, with spectral peaks near 10 and 20 Hz, is seen solely in response to stimulation. This activity consists of plane waves and spiral-like waves, as well as more complex patterns. The plane waves have an average phase gradient of ≈π/2 radians/mm and propagate orthogonally to the low frequency waves. Our results show that large-scale differences in neuronal timing are present and persistent during visual processing.

Increased sensitivity to apoptotic stimuli in c-abl-deficient progenitor B-cell lines

The protooncogene c-abl encodes a nonreceptor tyrosine kinase whose cellular function is unknown. To study the possible involvement of c-Abl in proliferation, differentiation, and cell cycle regulation of early B cells, long-term lymphoid bone marrow cultures were established from c-abl-deficient mice and their wild-type littermates. Interleukin 7-dependent progenitor B-cell clones and lines expressing B220 and CD43 could be generated from both mutant and wild-type mice. The mutant and wild-type lines displayed no difference in their proliferative capacity as measured by thymidine incorporation in response to various concentrations of interleukin 7. Similarly, c-abl deficiency did not interfere with the ability of mutant clones to differentiate into surface IgM-positive cells in vitro. Analysis of cultures after growth factor deprivation, however, revealed a strikingly accelerated rate of cell death in c-abl mutant cells, due to apoptosis as confirmed by terminal deoxynucleotidyltransferase-mediated UTP nick end labeling analysis. Furthermore, a greater susceptibility to apoptotic cell death in c-abl mutant cells was also observed after glucocorticoid treatment. These results suggest that mutant c-Abl renders the B-cell progenitors more sensitive to apoptosis, and may account for some of the phenotypes observed in c-abl-deficient animals.

Active hair-bundle movements can amplify a hair cell’s response to oscillatory mechanical stimuli

To enhance their mechanical sensitivity and frequency selectivity, hair cells amplify the mechanical stimuli to which they respond. Although cell-body contractions of outer hair cells are thought to mediate the active process in the mammalian cochlea, vertebrates without outer hair cells display highly sensitive, sharply tuned hearing and spontaneous otoacoustic emissions. In these animals the amplifier must reside elsewhere. We report physiological evidence that amplification can stem from active movement of the hair bundle, the hair cell’s mechanosensitive organelle. We performed experiments on hair cells from the sacculus of the bullfrog. Using a two-compartment recording chamber that permits exposure of the hair cell’s apical and basolateral surfaces to different solutions, we examined active hair-bundle motion in circumstances similar to those in vivo. When the apical surface was bathed in artificial endolymph, many hair bundles exhibited spontaneous oscillations of amplitudes as great as 50 nm and frequencies in the range 5 to 40 Hz. We stimulated hair bundles with a flexible glass probe and recorded their mechanical responses with a photometric system. When the stimulus frequency lay within a band enclosing a hair cell’s frequency of spontaneous oscillation, mechanical stimuli as small as ±5 nm entrained the hair-bundle oscillations. For small stimuli, the bundle movement was larger than the stimulus. Because the energy dissipated by viscous drag exceeded the work provided by the stimulus probe, the hair bundles powered their motion and therefore amplified it.

A serotonin transporter gene intron 2 polymorphic region, correlated with affective disorders, has allele-dependent differential enhancer-like properties in the mouse embryo

Polymorphic regions consisting of a variable number of tandem repeats within intron 2 of the gene coding for the serotonin transporter protein 5-HTT have been associated with susceptibility to affective disorders. We have cloned two of these intronic polymorphisms, Stin2.10 and Stin2.12, into an expression vector containing a heterologous minimal promoter and the bacterial LacZ reporter gene. These constructs were then used to produce transgenic mice. In embryonic day 10.5 embryos, both Stin2.10 and Stin2.12 produced consistent β-galactosidase expression in the embryonic midbrain, hindbrain, and spinal cord floor plate. However, we observed that the levels of β-galactosidase expression produced by both the Stin2.10 and Stin2.12 within the rostral hindbrain differed significantly at embryonic day 10.5. Our data suggest that these polymorphic variable number of tandem repeats regions act as transcriptional regulators and have allele-dependent differential enhancer-like properties within an area of the hindbrain where the 5-HTT gene is known to be transcribed at this stage of development.

Dynamic regulation of c-Jun N-terminal kinase activity in mouse brain by environmental stimuli

Activation of the recently identified c-Jun N-terminal kinases (JNKs) typically results in programmed cell death (apoptosis) in neurons and other cell types grown in culture. However, the effects of JNK activation in the central nervous system in vivo are unknown. At baseline, JNK activity in mice was on average 17-fold higher in brain than in peripheral organs, whereas JNK protein levels were similar. In brain, JNK was expressed primarily in neurons. Restraining mice or allowing them to explore a novel environment rapidly increased JNK activity 3- to 15-fold in various brain regions, but these manipulations did not increase brain activity of the extracellular signal-regulated kinase. Because noninvasive environmental stimuli that do not induce neurodegeneration elicited prominent increases in JNK activity in the brain, we conclude that acute activation of the JNK cascade in central nervous system neurons does not induce neuronal apoptosis in vivo. In contrast, the high baseline activity of JNK in the brain and the activation of the JNK cascade by environmental stimuli suggest that this kinase may play an important physiological role in neuronal function.

MEK kinase 1 is critically required for c-Jun N-terminal kinase activation by proinflammatory stimuli and growth factor-induced cell migration

Exposure of eukaryotic cells to extracellular stimuli results in activation of mitogen-activated protein kinase (MAPK) cascades composed of MAPKs, MAPK kinases (MAP2Ks), and MAPK kinase kinases (MAP3Ks). Mammals possess a large number of MAP3Ks, many of which can activate the c-Jun N-terminal kinase (JNK) MAPK cascade when overexpressed, but whose biological function is poorly understood. We examined the function of the MAP3K MEK kinase 1 (MEKK1) in proinflammatory signaling. Using MEKK1-deficient embryonic stem cells prepared by gene targeting, we find that, in addition to its function in JNK activation by growth factors, MEKK1 is required for JNK activation by diverse proinflammatory stimuli, including tumor necrosis factor α, IL-1, double-stranded RNA, and lipopolysaccharide. MEKK1 is also essential for induction of embryonic stem cell migration by serum factors, but is not required for activation of other MAPKs or the IκB kinase signaling cascade.

Assessment and discrimination of odor stimuli in rat olfactory bulb by dynamic functional MRI

Dynamic blood oxygenation level-dependent functional MRI was applied at 7 T in the rat olfactory bulb (OB) with pulsed delivery of iso-amyl acetate (IAA) and limonene. Acquisition times for single-slice and whole OB data were 8 and 32 s, respectively, with spatial resolution of 220 × 220 × 250 μm. On an intrasubject basis, short IAA exposures of 0.6 min separated by 3.5-min intervals induced reproducible spatial activity patterns (SAPs) in the olfactory nerve layer, glomerular layer, and external plexiform layer. During long exposures (≈10 min), the initially dominant dorsal SAPs declined in intensity and area, whereas in some OB regions, the initially weak ventral/lateral SAPs increased first and then decreased. The SAPs of different concentrations were topologically similar, which implies that whereas an odor at various concentrations activates the same subsets of receptor cells, different concentrations are assessed and discriminated by variable magnitudes of laminarspecific activations. IAA and limonene reproducibly activated different subsets of receptor cells with some overlaps. Whereas qualitative topographical agreement was observed with results from other methods, the current dynamic blood oxygenation level-dependent functional MRI results can provide quantitative SAPs of the entire OB.

The adaptor protein Crk connects multiple cellular stimuli to the JNK signaling pathway

c-Jun N-terminal kinases (JNKs) are potently activated by a number of cellular stimuli. Small GTPases, in particular Rac, are responsible for initiating the activation of the JNK pathways. So far, the signals leading from extracellular stimuli to the activation of Rac have remained elusive. Recent studies have demonstrated that the Src homology 2 (SH2)- and Src homology 3 (SH3)-containing adaptor protein Crk is capable of activating JNK when ectopically expressed. We found here that transient expression of Crk induces JNK activation, and this activation was dependent on both the SH2- and SH3-domains of Crk. Expression of p130Cas (Cas), a major binding protein for the Crk SH2-domain, also induced JNK activation, which was blocked by the SH2-mutant of Crk. JNK activation by Cas and Crk was effectively blocked by a dominant-negative form of Rac, suggesting for a linear pathway from the Cas-Crk-complex to the Rac-JNK activation. Many of the stimuli that activate the Rac-JNK pathway enhance engagement of the Crk SH2-domain. JNK activation by these stimuli, such as epidermal growth factor, integrin ligand binding and v-Src, was efficiently blocked by dominant-negative mutants of Crk. A dominant-negative form of Cas in turn blocked the integrin-, but not epidermal growth factor - nor v-Src-mediated JNK activation. Together, these results demonstrate an important role for Crk in connecting multiple cellular stimuli to the Rac-JNK pathway, and a role for the Cas-Crk complex in integrin-mediated JNK activation.

A genome-wide search for chromosomal loci linked to mental health wellness in relatives at high risk for bipolar affective disorder among the Old Order Amish

Bipolar affective disorder (BPAD; manic-depressive illness) is characterized by episodes of mania and/or hypomania interspersed with periods of depression. Compelling evidence supports a significant genetic component in the susceptibility to develop BPAD. To date, however, linkage studies have attempted only to identify chromosomal loci that cause or increase the risk of developing BPAD. To determine whether there could be protective alleles that prevent or reduce the risk of developing BPAD, similar to what is observed in other genetic disorders, we used mental health wellness (absence of any psychiatric disorder) as the phenotype in our genome-wide linkage scan of several large multigeneration Old Order Amish pedigrees exhibiting an extremely high incidence of BPAD. We have found strong evidence for a locus on chromosome 4p at D4S2949 (maximum genehunter-plus nonparametric linkage score = 4.05, P = 5.22 × 10−4; sibpal Pempirical value <3 × 10−5) and suggestive evidence for a locus on chromosome 4q at D4S397 (maximum genehunter-plus nonparametric linkage score = 3.29, P = 2.57 × 10−3; sibpal Pempirical value <1 × 10−3) that are linked to mental health wellness. These findings are consistent with the hypothesis that certain alleles could prevent or modify the clinical manifestations of BPAD and perhaps other related affective disorders.

Electric Signaling and Pin2 Gene Expression on Different Abiotic Stimuli Depend on a Distinct Threshold Level of Endogenous Abscisic Acid in Several Abscisic Acid-Deficient Tomato Mutants1

Experiments were performed on three abscisic acid (ABA)-deficient tomato (Lycopersicon esculentum Mill.) mutants, notabilis, flacca, and sitiens, to investigate the role of ABA and jasmonic acid (JA) in the generation of electrical signals and Pin2 (proteinase inhibitor II) gene expression. We selected these mutants because they contain different levels of endogenous ABA. ABA levels in the mutant sitiens were reduced to 8% of the wild type, in notabilis they were reduced to 47%, and in flacca they were reduced to 21%. In wild-type and notabilis tomato plants the induction of Pin2 gene expression could be elicited by heat treatment, current application, or mechanical wounding. In flacca and sitiens only heat stimulation induced Pin2 gene expression. JA levels in flacca and sitiens plants also accumulated strongly upon heat stimulation but not upon mechanical wounding or current application. Characteristic electrical signals evolved in the wild type and in the notabilis and flacca mutants consisting of a fast action potential and a slow variation potential. However, in sitiens only heat evoked electrical signals; mechanical wounding and current application did not change the membrane potential. In addition, exogenous application of ABA to wild-type tomato plants induced transient changes in membrane potentials, indicating the involvement of ABA in the generation of electrical signals. Our data strongly suggest the presence of a minimum threshold value of ABA within the plant that is essential for the early events in electrical signaling and mediation of Pin2 gene expression upon wounding. In contrast, heat-induced Pin2 gene expression and membrane potential changes were not dependent on the ABA level but, rather, on the accumulation of JA.

The affective component of pain in rodents: Direct evidence for a contribution of the anterior cingulate cortex

Numerous human and animal studies indirectly implicate neurons in the anterior cingulate cortex (ACC) in the encoding of the affective consequences of nociceptor stimulation. No causal evidence, however, has been put forth linking the ACC specifically to this function. Using a rodent pain assay that combines the hind-paw formalin model with the place-conditioning paradigm, we measured a learned behavior that directly reflects the affective component of pain in the rat (formalin-induced conditioned place avoidance) concomitantly with “acute” formalin-induced nociceptive behaviors (paw lifting, licking, and flinching) that reflect the intensity and localization of the nociceptive stimulus. Destruction of neurons originating from the rostral, but not caudal, ACC reduced formalin-induced conditioned place avoidance without reducing acute pain-related behaviors. These results provide evidence indicating that neurons in the ACC are necessary for the “aversiveness” of nociceptor stimulation.

Identification of vascular endothelial genes differentially responsive to fluid mechanical stimuli: cyclooxygenase-2, manganese superoxide dismutase, and endothelial cell nitric oxide synthase are selectively up-regulated by steady laminar shear stress.

Early atherosclerotic lesions develop in a topographical pattern that strongly suggests involvement of hemodynamic forces in their pathogenesis. We hypothesized that certain endothelial genes, which exhibit differential responsiveness to distinct fluid mechanical stimuli, may participate in the atherogenic process by modulating, on a local level within the arterial wall, the effects of systemic risk factors. A differential display strategy using cultured human endothelial cells has identified two genes, manganese superoxide dismutase and cyclooxygenase-2, that exhibit selective and sustained up-regulation by steady laminar shear stress (LSS). Turbulent shear stress, a nonlaminar fluid mechanical stimulus, does not induce these genes. The endothelial form of nitric oxide synthase also demonstrates a similar LSS-selective pattern of induction. Thus, three genes with potential atheroprotective (antioxidant, antithrombotic, and antiadhesive) activities manifest a differential response to distinct fluid mechanical stimuli, providing a possible mechanistic link between endothelial gene expression and early events in atherogenesis. The activities of these and other LSS-responsive genes may have important implications for the pathogenesis and prevention of atherosclerosis.

Localization of visual stimuli after striate cortex damage in monkeys: parallels with human blindsight.

Blindsight is a phenomenon in which human patients with damage to striate cortex deny any visual sensation in the resultant visual field defect but can nonetheless detect and localize stimuli when persuaded to guess. Although monkeys with striate lesions have also been shown to exhibit some residual vision, it is not yet clear to what extent the residual capacities in monkeys parallel the phenomenon of human blindsight. To clarify this issue, we trained two monkeys with unilateral lesions of striate cortex to make saccadic eye movements to visual targets in both hemifields under two conditions. In the condition analogous to clinical perimetry, they failed to initiate saccades to targets presented in the contralateral hemifield and thus appeared "blind." Only in the condition where the fixation point was turned off simultaneously with the onset of the target--signaling the animal to respond at the appropriate time--were monkeys able to localize targets contralateral to the striate lesion. These results indicate that the conditions under which residual vision is demonstrable are similar for monkeys with striate cortex damage and humans with blindsight.