Neural correlates of sexual arousal in homosexual and heterosexual men.

Men exhibit much higher levels of genital and subjective arousal to sexual stimuli containing their preferred sex than they do to stimuli containing only the nonpreferred sex. This study used event-related functional magnetic resonance imaging to investigate how this category-specific pattern would be reflected in the brains of homosexual (n = 11) and heterosexual (n = 11) men. Comparisons of activation to preferred sexual stimuli, nonpreferred sexual stimuli, and sports stimuli revealed large networks correlated with sexual arousal, spanning multiple cortical and subcortical areas. Both homosexual and heterosexual men exhibited category-specific arousal in brain activity. Within the amygdala, greater preference-related activity was observed in homosexual men, but it is unclear whether this is a cause or a consequence of their sexuality. In a subsequent analysis of regions hypothesized to support arousal, both participant groups demonstrated widespread increases in evoked activity for preferred stimuli. Aggregate data from these regions produced significant differences between stimulus types in 16 out of 22 participants. Significant activational differences matched reported sexual orientation in 15 of these 16 participants, representing an advance in psychophysiological measures of arousal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple mechanisms of visual-spatial attention: recent evidence from human electrophysiology

Natural visual scenes contain vast quantities of information--far more than the visual system can process in a short period of time-and spatial attention is therefore used to focus the visual system's processing resources onto a subset of the incoming visual information. Most psychological theories of attention posit a single mechanism for this focusing of attention, but recent electrophysiological studies have provided evidence that the visual system employs several separable neural mechanisms of spatial attention. This paper describes the evidence for multiple attentional mechanisms and suggests links between these neurophysiologically defined mechanisms and specific functional processes that have been proposed in psychological theories of attention.     

Spatio-temporal dynamics of attention to color: evidence from human electrophysiology

This study characterized patterns of brain electrical activity associated with selective attention to the color of a stimulus. Multichannel recordings of event-related potentials (ERPs) were obtained while subjects viewed randomized sequences of checkerboards consisting of isoluminant red or blue checks superimposed on a grey background. Stimuli were presented foveally at a rapid rate, and subjects were required to attend to the red or blue checks in separate blocks of trials and to press a button each time they detected a dimmer target stimulus of the attended color. An early negative ERP component with an onset latency of 50 ms was sensitive to stimulus color but was unaffected by the attentional manipulation. ERPs elicited by attended and unattended stimuli began to diverge after approximately 100 ms following stimulus onset. Inverse dipole modelling of the attended-minus-unattended difference waveform indicated that an initial positive deflection with an onset latency of 100 ms had a source in lateral occipital cortex, while a subsequent negative deflection with an onset at 160 ms had a source in inferior occipito-temporal cortex. Longer-latency attention-sensitive components were localized to premotor frontal areas (onset at 190 ms) and to more anterior regions of the fusiform gyrus (onset at 240 ms). These source localizations correspond closely with cortical areas that were identified in previous neuroimaging studies as being involved in color-selective processing. The present ERP data thus provide information about the time course of stimulus selection processes in cortical areas that subserve attention to color.     

Perceived arousal, focus of attention, and avoidance behavior.

Attribution theory holds that perceived arousal may cause a person to draw an inference about his emotions and base his subsequent behavior on that inference. Recent research suggests, however, that this account does not entirely explain the influence of false arousal feedback on simultaneously occurring avoidance behavior. The following model, based on self-awareness theory, is proposed. Autonomic arousal feedback may cause heightened self-focus, followed by 1 of 2 possibilities: (a) If the person believes he can cope with his fear, he will redirect his attention to a behavior–goal comparison in order to match the one with the other. (b) If the person doubts his ability to match his behavior with the goal, such a comparison will be aversive and he will avoid focusing on it. These possibilities should lead to 2 different behavioral reactions as well: Doubtful Ss should avoid the aversive stimulus more quickly when presented with arousal feedback, but confident Ss should not. To test the model, a study was conducted in which 57 undergraduates who had self-rated moderate fear of nonpoisonous snakes and who also had indicated either confidence or doubt about their abilities to do the approach task approached a live boa constrictor in the presence of an accelerating or a constant heartbeat. Both behavioral and self-reported focus of attention results were consistent with the proposed attentional model. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual arousal in response to aggression: Ideological, aggressive, and sexual correlates.

In Exp I, 37 male and 42 female undergraduates reported more sexual arousal in response to nonaggressive than to aggressive depictions when the portrayals were sexually explicit, but the opposite occurred when the portrayals were nonsexual. In Exp II, 367 males were classified into no arousal, moderate arousal, or high arousal from force (AFF) groups on the basis of self-reports. To evaluate the veridicality of this classification, 118 Ss' penile tumescence in response to various depictions was assessed. Findings generally replicate those of the Exp I and confirm the accuracy of the AFF classification. The no- and the moderate-AFF Ss were less sexually aroused by aggressive than by nonaggressive portrayals, but the opposite was found for the high-AFF group. Strong differences between AFF groups were found on ideological factors, including acceptance of violence against and dominance over women, acceptance of nonsexual aggression, and Ss' beliefs that they might actually use force against women. In contrast, differences were not found on sexuality factors. Implications for theories on the causes of rape are discussed. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An examination of attention, arousal, and learning dysfunctions of hyperkinetic children.

Reviews empirical studies that have supported viewing the hyperkinetic syndrome and the related diagnoses of minimal brain dysfunction and learning disability as dysfunctions of information processing. Data on measures of arousal, attention, learning, and performance were examined for undrugged hyperkinetics, hyperkinetics given stimulant medication, and nonhyperkinetic children. Although support was found for the hypotheses that hyperkinetics exhibit low physiological arousal and poor attention, several findings indicate the need for modifying these hypotheses. Little evidence was found for the hypothesis that hyperkinetics have reduced sensitivity to reinforcement. Some theoretical clarifications of the arousal and attention hypotheses are proposed, and some directions for future empirical work are suggested. (3 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuronal correlates of sleep, wakefulness and arousal in a diurnal insect

The discovery that various states of sleep, rest, wakefulness and arousal in man can be correlated with specific forms of the electroencephalogram1 has led to intensive studies of these states, mostly in mammals2-5. Today it is generally accepted that circadian sleep-wakefulness cycles occur in mammals and birds2,3,6. Behavioural observations on sleep in moths have also been published7; many other invertebrates demonstrate rest/activity cycles8. Circadian sensitivity fluctuations in both central9 and peripheral10-15 components of the visual system of various nocturnal arthropod species have been demonstrated. We now report that long-term, extracellular, single-unit recordings from optomotor interneurones in the optic lobes of forager honey bees reveal an oscillation in their sensitivity to moving visual stimuli16, 17. The oscillation displays properties typical of a circadian rhythm6, 18. The sensitivity of the neurons is higher during the subjective day than during the subjective night. The locomotor activity of individual, fixed walking forager bees shows a similar circadian oscillation and is also higher during the subjective day. Visual and mechanical stimuli can act directly on the interneurones and restore their sensitivity during times of reduced neuronal responsiveness. A comparison with results available for mammals makes it likely that the neuronal phenomena presented here are correlates of the bee's circadian sleep-wakefulness rhythm.     

Race, arousal, attention, exposure and delay: An examination of factors moderating face recognition.

A large percentage of people recently exonerated by DNA evidence were imprisoned on the basis of faulty eyewitness identification. Many of these cases involved victims and suspects of different races. Two studies examined the recognition of Hispanic and Black target faces by Hispanic participants under nonoptimal viewing conditions. When viewing time decreased, recognition performance for same- and other-race faces systematically shifted downward. Recognition accuracy for faces of both races decreased under conditions of high negative arousal and attention load; however, recognition of same-race faces was differentially affected by attention distractors. Face recognition accuracy was not affected by a delay between initial presentation of the faces and the face recognition test. An understanding of how recognition of other-race persons differs from that of same-race persons can assist by reducing misidentifications and ensuring that the perpetrator rather than an innocent person is imprisoned. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural synchrony in stochastic resonance, attention, and consciousness.

We describe briefly three of our lab's ongoing projects studying the role of neural synchrony in human perception and cognition. These projects arise from two main interests: the role of noise both in human perception and in neural synchrony, and neural synchrony as a basis for integration of functional modules in the brain. Our experimental work on these topics began with a study of the possibility that noise-influenced neural synchrony might be responsible for the fact that small amounts of noise added to weak signals can enhance their detectability (stochastic resonance). We are also studying the role of neural synchrony in attention and consciousness in several paradigms. On the basis of our own and related work by others, we conclude that (1) neural synchrony plays an important role in the integration of functional modules in the brain and (2) neural synchrony is profoundly affected and possibly regulated, in part, by the "noisiness" of the brain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assumptions and validations of statistical tests for functional neuroimaging

We contrast two statistical methods: three-dimensional cluster analysis and statistical parametric mapping. We show that three-dimensional cluster analysis is based on a neurobiological theory of the regulation of blood flow and, unlike statistical parametric mapping, carries a minimum of assumptions that are tested. Statistical parametric mapping is a formal approach, which is based on a multitude of assumptions of which the majority have not been validated. We also demonstrate that in practice three-dimensional cluster analysis has a reasonable balance between sensitivity and the probability of false positives, giving high reproducibility with data on e.g. colour discrimination.     

Monogenean neuromusculature: some structural and functional correlates

Monogenean neuromuscular systems are structurally and functionally well-differentiated, as evidenced by research on the fish-gill parasite, Diclidophora merlangi. The nervous system in the worm exhibits a raft of putative intercellular signalling molecules, localised in neuronal vesicles. There is cytochemical evidence of co-localisation of neuropeptides and cholinergic substances, with aminergic components generally occupying separate neurons. The phalloidin-fluorescence technique for F-actin has enabled the demonstration of muscle organisation in the worm. Body wall musculature comprises circular, longitudinal and diagonal arrays of myofibres whose contractions are believed to be largely myogenic; circular fibres predominate in the walls of the reproductive tracts. The major somatic muscles are longitudinal muscle bundles that traverse the mesenchyme, the most extensive of which extend from the pharynx to the clamps of the haptor. Experiments have shown that some of these muscles may serve in a withdrawal reflex in the worm, which can be evoked by water turbulence. These and the muscles of the suckers, pharynx, clamps, male copulatory organ and ootype are provided with extensive synaptic innervation that is strongly immunoreactive for FMRFamide-related peptides (FaRPs), suggesting contractions may be neurogenic. Examination of the physiological effects of known flatworm FMRFamide-related peptides on muscle contractility in vitro has shown those FMRFamide-related peptides isolated from turbellarians to be the most excitatory. Results are discussed with respect to neuromuscular function in adhesion, alimentation, and reproduction in the worm.     

Cardiac protein phosphorylation: functional and pathophysiological correlates

Protein phosphorylation acts a pivotal mechanism in regulating the contractile state of the heart by modulating particular levels of autonomic control on cardiac force/length relationships. Early studies of changes in cardiac protein phosphorylation focused on key components of the excitation-coupling process, namely phospholamban of the sarcoplasmic reticulum and myofibrillar troponin I. In more recent years the emphasis has shifted towards the identification of other phosphoproteins, and more importantly, the delineation of the mechanistic and signaling pathways regulating the various known phosphoproteins. In addition to cAMP- and Ca(2+)-calmodulin-dependent kinase processes, these have included regulation by protein kinase C and the ever-emerging family of growth factor-related kinases such as the tyrosine-, mitogen- and stress-activated protein kinases. Similarly, the role of protein dephosphorylation by protein phosphatases has been recognized as integral in modulating normal cardiac cellular function. Recent studies involving a variety of cardiovascular pathologies have demonstrated that changes in the phosphorylation states of key cardiac regulatory proteins may underlie cardiac dysfunction in disease states. The emphasis of this comprehensive review will be on discussing the role of cardiac phosphoproteins in regulating myocardial function and pathophysiology based not only on in vitro data, but more importantly, from ex vivo experiments with corroborative physiological and biochemical evidence.     

Prediction of children's reading skills using behavioral, functional, and structural neuroimaging measures.

The ability to decode letters into language sounds is essential for reading success, and accurate identification of children at high risk for decoding impairment is critical for reducing the frequency and severity of reading impairment. We examined the utility of behavioral (standardized tests), and functional and structural neuroimaging measures taken with children at the beginning of a school year for predicting their decoding ability at the end of that school year. Specific patterns of brain activation during phonological processing and morphology, as revealed by voxel-based morphometry (VBM) of gray and white matter densities, predicted later decoding ability. Further, a model combining behavioral and neuroimaging measures predicted decoding outcome significantly better than either behavioral or neuroimaging models alone. Results were validated using cross-validation methods. These findings suggest that neuroimaging methods may be useful in enhancing the early identification of children at risk for poor decoding and reading skills. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Respiratory arousal from sleep: mechanisms and significance

The mechanisms by which respiratory stimuli induce arousal from sleep and the clinical significance of these arousals have been explored by numerous studies in the last two decades. Evidence to date suggests that the arousal stimulus in nonrapid eye movement sleep (NREM) is related to the level of inspiratory effort rather than the individual stimuli that contribute to ventilatory drive. A component of the arousal stimulus proportional to the level of inspiratory effort may originate in mechanoreceptors either in the upper airway or respiratory pump. Medullary centers responsible for ventilatory drive may also send a signal proportionate to the level of drive to higher centers in the brain which are responsible for arousal. Thus, the arousal stimulus may consist of multiple components, each increasing as inspiratory effort increases. The level of effort triggering arousal is an index of the arousability of the brain (arousal threshold). A deeper stage of sleep, central nervous system depressants, prior sleep fragmentation, and the presence of obstructive sleep apnea (OSA) have been observed to increase the arousal threshold to airway occlusion. Less information is available concerning the mechanisms of arousal from rapid eye movement (REM) sleep. While REM sleep is associated with the longest obstructive apneas in patients with OSA, normal human subjects appear to have a similar or lower arousal threshold to respiratory stimuli in REM compared to NREM sleep. Recent studies have challenged the assumption that the termination of all obstructive apnea is dependent on arousal from sleep. Improvements in methods to detect and quantitate changes in the cortical electroencephalogram (EEG) may better define the relationship between arousal and apnea termination. This may result in improved criteria for identifying EEG changes of clinical significance. While little is known concerning the mechanisms of arousal in central sleep apnea, arousal may play an important role in inducing this type of apnea in some patients.     

A review of functional neuroimaging in mood disorders: positron emission tomography and depression

OBJECTIVE: To examine the progress of positron emission tomography (PET) as a tool for understanding the psychobiology of mood disorders, particularly major depression and bipolar disorder. METHOD: Review of the literature on functional imaging of mood disorders. RESULTS: Functional imaging techniques have been used in psychiatric research as a noninvasive method to study the behaviour and function of the brain. Techniques used so far have involved the manipulation of emotion in healthy volunteers, the evaluation of depressed (unipolar and bipolar as well as secondary depression), manic, and normal subjects under resting and various activation conditions, such as cognitive activation, acute pharmacological challenge, and chronic thymoleptic treatments. As a result, functional imaging studies tend to support abnormalities in specific frontal and limbic regions. CONCLUSION: Different PET methods demonstrate consistent abnormalities in the prefrontal, cingulate, and amygdala regions. These findings are in agreement with past animal and clinical anatomical correlates of mood and emotions.     

Neural correlates of semantic and episodic memory retrieval

To investigate the functional neuroanatomy associated with retrieving semantic and episodic memories, we measured changes in regional cerebral blood flow (rCBF) with positron emission tomography (PET) while subjects generated single word responses to achromatic line drawings of objects. During separate scans, subjects either named each object, retrieved a commonly associated color of each object (semantic condition), or recalled a previously studied uncommon color of each object (episodic condition). Subjects were also scanned while staring at visual noise patterns to provide a low level perceptual baseline. Relative to the low level baseline, all three conditions revealed bilateral activations of posterior regions of the temporal lobes, cerebellum, and left lateralized activations in frontal regions. Retrieving semantic information, as compared to object naming, activated left inferior temporal, left superior parietal, and left frontal cortices. In addition, small regions of right frontal cortex were activated. Retrieving episodic information, as compared to object naming, activated bilateral medial parietal cortex, bilateral retrosplenial cortex, right frontal cortex, thalamus, and cerebellum. Direct comparison of the semantic and episodic conditions revealed bilateral activation in temporal and frontal lobes in the semantic task (left greater than right), and activation in medial parietal cortex, retrosplenial cortex, thalamus, and cerebellum (but not right frontal regions) in the episodic task. These results support the assertion that distinct neural structures mediate semantic and episodic memory retrieval. However, they also raise questions regarding the specific roles of left temporal and right frontal cortices during episodic memory retrieval, in particular.     

Neural correlates of depth of processing effects on recollection: evidence from brain potentials and positron emission tomography

The probability that words would be recollected during tests of recognition memory was varied by manipulating depth of processing at study. Experiment 1 employed scalp-recorded event-related potentials (ERPs), and identified as a correlate of recollection a late (onset c. 500 ms), strongly left-lateralized positive-going modulation of the ERP waveform. The findings from experiment 2, which employed positron emission tomography (PET), indicated that recollection was associated with activation of the left hippocampal formation together with an extensive region of left temporal and frontal cortex. The findings support current ideas about the role of the hippocampal formation in episodic memory retrieval, and provide complementary information about the time course and localization of the cortical correlates of the recollection of recently experienced words.     

Allocation of spatial attention to emotional stimuli depends upon arousal and not valence.

Attentional allocation to emotional stimuli is often proposed to be driven by valence and in particular by negativity. However, many negative stimuli are also arousing leaving the question whether valence or arousal accounts for this effect. The authors examined whether the valence or the arousal level of emotional stimuli influences the allocation of spatial attention using a modified spatial cueing task. Participants responded to targets that were preceded by cues consisting of emotional pictures varying on arousal and valence. Response latencies showed that disengagement of spatial attention was slower for stimuli high in arousal than for stimuli low in arousal. The effect was independent of the valence of the pictures and not gender-specific. The findings support the idea that arousal affects the allocation of attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment of Alzheimer's disease with sabeluzole: functional and structural correlates

Sabeluzole, a new benzothiazole derivative, has been shown to be neurobiologically active preclinically and clinically appears to exert beneficial effects on memory. In this study, sabeluzole (5 or 10 mg twice daily vs. placebo) was investigated in patients with probable Alzheimer's disease over 1 year, with assessments of cognitive performance and structural changes. Cognitive performance was measured using the Alzheimer's Disease Assessment Scale periodically during treatment. Potential structural correlates in the frontal horn, caudate, third ventricle and hippocampal regions were examined by obtaining computerized tomographic (CT) images before and after treatment. Patients receiving sabeluzole evidenced greater stability than did placebo-treated patients in some cognitive measures. CT measures showed no significant changes from baseline, but some weak associations were found between relative preservation of cognitive function and smaller structural declines in the third ventricle and hippocampus. Cognitive outcome measures suggest that sabeluzole may have potential in slowing the cognitive deterioration of Alzheimer's disease. Furthermore, the method used to explore potential benefits on a morphologic level, although negative in this study, could yet have potential.