A test of the generality of perceptually based categories found in infants: attentional differences toward natural kinds by New World monkeys

A preference to novelty paradigm used to study human infants (Quinn, 2002) examined attention to novel animal pictures at subordinate, basic and superordinate levels in tamarins. First, pairs of pictures were presented in phases, starting with a monkey species (subordinate level) and ending with mammal and dinosaur sets (superordinate levels). After each phase, tests paired novel pictures from the familiarized set with a novel broader category. Look rates toward each picture were coded. Tamarins looked significantly longer at a novel species after being familiarized with a monkey species, a species-specific effect. Subjects attended equivalently to novel primate species after habituation to four monkey species, but looked significantly longer at pictures of mammals, marking a more global-level inclusion and exclusion. Superordinate testing revealed that more novel and diverse sets were differentiated attentionally. The evidence implies that natural categorical representation occurs at an attentional level in primates in ways similar to human infants, and is affected by recent exposure and category variability.

Linkage and association of the mitochondrial aspartate/glutamate carrier SLC25A12 gene with autism

OBJECTIVE

Autism/autistic disorder (MIM number 209850) is a complex, largely genetic psychiatric disorder. The authors recently mapped a susceptibility locus for autism to chromosome region 2q24-q33 (MIM number 606053). In the present study, genes across the 2q24-q33 interval were analyzed to identify an autism susceptibility gene in this region.

METHOD

Mutation screening of positional candidate genes was performed in two stages. The first stage involved identifying, in unrelated subjects showing linkage to 2q24-q33, genetic variants in exons and flanking sequence within candidate genes and comparing the frequency of the variants between autistic and unrelated nonautistic subjects. Two single nucleotide polymorphisms (SNPs) that showed evidence for divergent distribution between autistic and nonautistic subjects were identified, both within SLC25A12, a gene encoding the mitochondrial aspartate/glutamate carrier (AGC1). In the second stage, the two SNPs in SLC25A12 were further genotyped in 411 autistic families, and linkage and association tests were carried out in the 197 informative families.

RESULTS

Linkage and association were observed between autistic disorder and the two SNPs, rs2056202 and rs2292813, found in SLC25A12. Using either a single affected subject per family or all affected subjects, evidence for excess transmission was found by the Transmission Disequilibrium Test for rs2056202, rs2292813, and a two-locus G*G haplotype. Similar results were observed using TRANSMIT for the analyses. Evidence for linkage was supported by linkage analysis with the two SNPs, with a maximal multipoint nonparametric linkage score of 1.57 and a maximal multipoint heterogeneity lod score of 2.11. Genotype relative risk could be estimated to be between 2.4 and 4.8 for persons homozygous at these loci.

CONCLUSIONS

A strong association of autism with SNPs within the SLC25A12 gene was demonstrated. Further studies are needed to confirm this association and to decipher any potential etiological role of AGC1 in autism.

A systems approach to orbitofrontal cortex function: recordings in rat orbitofrontal cortex reveal interactions with different learning systems

The recognition that certain aspects of prefrontal function can be effectively modeled in rats has led to a slow expansion of interest in rat prefrontal cortex over the past decade. One of the most promising of these model systems is the orbitofrontal cortex of the rat. Rat orbitofrontal cortex is anatomically similar to the orbital prefrontal region in primates, and this similarity is borne out by behavioral and neurophysiological findings. Here we will present data on orbitofrontal cortex function from a number of parallel studies from our laboratories that employed single unit recording techniques to probe neural encoding in rat orbitofrontal cortex and related parts of the amygdala and the hippocampal memory systems. Together, these reports and associated behavioral studies suggest that the orbitofrontal region, in both rats and primates, is specialized to integrate concrete and abstract sensory constructs with information regarding the incentive value of associated outcomes to guide or modulate behavior. To the extent that monkey prefrontal function can model certain aspects of human prefrontal function, we argue that this model can now be extended to the rat orbitofrontal cortex. In addition, we argue that the function of orbitofrontal cortex needs to be considered in terms of its interactions with other brain systems.

The Construction of Experience: A Longitudinal Study of Representation and Behavior

Continuity in relationship representation and developmental links between relationship representation and behavior from infancy to late adolescence were examined using longitudinal data from a risk sample (N = 185). Significant correlations were found among diverse representational assessments (e.g., interview, drawing, projective narrative) and between representational and concurrent observational measures of relationship functioning. Structural equation models were analyzed to investigate the relations among caregiving experience in infancy; relationship representation and experience in early childhood, middle childhood, and early adolescence; and socioemotional functioning in adolescence. A model representing interactive contributions of representational and behavioral experience represented the data significantly better than a model representing noninteractive contributions. Findings support an organizational developmental view that socioemotional adaptation arises from the progressive construction of mutually informing expectations and experience.

Perceptual and Acoustic Evidence for Species-Level Differences in Meow Vocalizations by Domestic Cats (Felis catus} and African Wild Cats (Felis silvestris lybica)

To test for possible anthropogenic selection effects on meows in domestic felids, vocalizations by domestic cats (Felis catus) were compared with cries by their closest wild relative, the African wild cat (Felis silvestris lybica). Comparisons included analysis of acoustic characteristics and perceptual studies with human (Homo sapiens) listeners. The perceptual studies obtained human listener ratings of call pleasantness. Both the acoustic and perceptual comparisons revealed clear species-level differences: The domestic cat meows were significantly shorter in mean duration than the wild cat meows, showed higher mean formant frequencies, and exhibited higher mean fundamental frequencies. Human listeners at all levels of experience and affinity for cats rated domestic cat meows as far more pleasant sounding than wild cat vocalizations. These results are consistent with a model of cat domestication that posits selective pressure on meows based on human perceptual biases.

Sensitivity and specificity of select biological indices in characterizing psychotic patients and their relatives

BACKGROUND

Although studies have detailed biological abnormalities in schizophrenia patients and their first-degree biological relatives, few studies have directly compared the utility of biological indices in these individuals.

METHODS

Measures of global smooth-pursuit ocular motor (OM) function, low frequency and alpha band electroencephalogram (EEG) power, and nonspecific fluctuations (NSF) in electrodermal activity and visibility of the plexus in the nailfold were collected from 136 schizophrenia patients and 67 of their first-degree biological relatives, 71 affective disorder psychotic patients and 68 of their first-degree biological relatives, and 169 nonpsychiatric comparison subjects. We conducted receiver operator characteristic (ROC) analyses to determine how well each index differentiated the patient groups and the groups of first-degree relatives.

RESULTS

Smooth-pursuit ocular motor function, low frequency and alpha band EEG power, and nailfold plexus visibility differentiated schizophrenia patients from nonpsychiatric comparison subjects. Nailfold plexus visibility was the only measure that significantly differentiated schizophrenia patients from both nonpsychiatric controls and affective patients. Smooth-pursuit ocular motor function and the number of electrodermal nonspecific fluctuations differentiated relatives of schizophrenia patients from nonpsychiatric comparison subjects.

CONCLUSION

Increased nailfold plexus visibility may mark a process associated with abnormal brain development leading to schizophrenia. Smooth-pursuit dysfunction may mark genetic vulnerability that is relatively specific to schizophrenia.

Monoaminergic changes associated with socially induced sex reversal in the saddleback wrasse

The process of sex reversal in fishes is socially mediated and requires a total reorganization of the hypothalamo-pituitary-gonadal axis. When the ratio of males to females in a population of saddleback wrasse (Thalassoma dupperrey) is too low, the largest female becomes male over the course of 6 to 8 weeks. This event requires the conversion of external social cues into internal chemical cues. In an attempt to investigate the role monoamines might play in this process, two females were housed together in floating enclosures in order to induce sex reversal in the larger. Brains were sampled at various time points throughout the process of sex reversal. Monoamines were measured in the amygdala, preoptic area, ventral hypothalamus, locus coeruleus and raphe nucleus. Changes were demonstrated in monoamine metabolism for all brain regions examined. The most important changes in monoamine-system activation were seen during the first week of sex reversal. It is during this time that transitional animals undergo behavioral sex reversal. There is an increase in serotonergic activity in the amygdala which is likely related to territorial acquisition. The absence of male aggression results in a less stressful environment for the female and a reduction in serotonergic activity in the preoptic area allowing for an increase in noradrenergic activity potentially triggering the reorganization of the reproductive axis. In the ventral hypothalamus, there is a decrease in noradrenergic and increase in dopaminergic activity associated with this change from female to male. The locus coeruleus shows an increase in noradrenergic activity later in the process of sex reversal which is probably a response to more circulating androgens. In the raphe nucleus, there is a decrease in serotonergic activity at the time of behavioral sex reversal. This decrease in serotonergic activity is linked to the behavioral component of sex reversal. This study suggests that monoamines play a very important role in both behavioral and gonadal sex reversal in the saddleback wrasse, the former under the control of serotonin in the raphe and the latter mediated via serotonergic effects on norepinephrine in the preoptic area.

Epileptic seizure prediction using hybrid feature selection over multiple intracranial EEG electrode contacts: a report of four patients

Epileptic seizure prediction has steadily evolved from its conception in the 1970s, to proof-of-principle experiments in the late 1980s and 1990s, to its current place as an area of vigorous, clinical and laboratory investigation. As a step toward practical implementation of this technology in humans, we present an individualized method for selecting electroencephalogram (EEG) features and electrode locations for seizure prediction focused on precursors that occur within ten minutes of electrographic seizure onset. This method applies an intelligent genetic search process to EEG signals simultaneously collected from multiple intracranial electrode contacts and multiple quantitative features derived from these signals. The algorithm is trained on a series of baseline and preseizure records and then validated on other, previously unseen data using split sample validation techniques. The performance of this method is demonstrated on multiday recordings obtained from four patients implanted with intracranial electrodes during evaluation for epilepsy surgery. An average probability of prediction (or block sensitivity) of 62.5% was achieved in this group, with an average block false positive (FP) rate of 0.2775 FP predictions/h, corresponding to 90.47% specificity. These findings are presented as an example of a method for training, testing and validating a seizure prediction system on data from individual patients. Given the heterogeneity of epilepsy, it is likely that methods of this type will be required to configure intelligent devices for treating epilepsy to each individual's neurophysiology prior to clinical deployment.

Detection of seizure precursors from depth-EEG using a sign periodogram transform

Brief bursts of focal, low amplitude rhythmic activity have been observed on depth electroencephalogram (EEG) in the minutes before electrographic onset of seizures in human mesial temporal lobe epilepsy. We have found these periods to contain discrete, individualized synchronized activity in patient-specific frequency bands ranging from 20 to 40 Hz. We present a method for detecting and displaying these events using a periodogram of the sign-limited temporal derivative of the EEG signal, denoted joint sign periodogram event characterization transform (JSPECT). When applied to continuous 2-6 day depth-EEG recordings from ten patients with temporal lobe epilepsy, JSPECT demonstrated that these patient-specific EEG events reliably occurred 5-80 s prior to electrical onset of seizures in five patients with focal, unilateral seizure onsets. JSPECT did not reveal this type of activity prior to seizures in five other patients with bilateral, extratemporal or more diffuse seizure onsets on EEG. Patient-specific, localized rhythmic events may play an important role in seizure generation in temporal lobe epilepsy. The JSPECT method efficiently detects these events, and may be useful as part of an automated system for predicting electrical seizure onset in appropriate patients.

Classification of domestic cat (Felis catus) vocalizations by naive and experienced human listeners

To test for possible functional referentiality in a common domestic cat (Felis catus) vocalization, the authors conducted 2 experiments to examine whether human participants could classify meow sounds recorded from 12 different cats in 5 behavioral contexts. In Experiment 1, participants heard singlecalls, whereas in Experiment 2, bouts of calls were presented. In both cases, classification accuracy was significantly above chance, but modestly so. Accuracy for bouts exceeded that for single calls. Overall, participants performed better in classifying individual calls if they had lived with, interacted with, and had a general affinity for cats. These results provide little evidence of referentiality suggesting instead that meows are nonspecific, somewhat negatively toned stimuli that attract attention from humans. With experience, human listeners can become more proficient at inferring positive-affect states from cat meows.

Monoamines stimulate sex reversal in the saddleback wrasse

Monoamine neurotransmitters (norepinephrine, dopamine, and serotonin) play an important role in reproduction and sexual behavior throughout the vertebrates. They are the first endogenous chemical signals in the regulation of the hypothalamo-pituitary-gonadal (HPG) axis. In teleosts with behavioral sex determination, much is known about behavioral cues that induce sex reversal. The cues are social, processed via the visual system and depend on the ratio of females to males in the population. The mechanisms by which these external behavioral cues are converted to an internal chemical regulatory process are largely unknown. The protogynous Hawaiian saddleback wrasse, Thalassoma duperrey, was used to investigate the biological pathway mediating the conversion of a social cue into neuroendocrine events regulating sex reversal. Because monoamines play an important role in the regulation of the HPG axis, they were selected as likely candidates for such a conversion. To determine if monoamines could affect sex reversal, drugs affecting monoamines were used in an attempt to either induce sex reversal under non-permissive conditions, or prevent sex reversal under permissive conditions. Increasing norepinephrine or blocking dopamine or serotonin lead to sex reversal in experimental animals under non-permissive conditions. Increasing serotonin blocked sex reversal under permissive conditions, while blocking dopamine or norepinephrine retarded the process. The results presented here demonstrate that monoamines contribute significantly to the control sex reversal. Norepinephrine stimulates initiation and completion of gonadal sex of reversal as well as color change perhaps directly via its effects on the HPG axis. Dopamine exercises inhibitory action on the initiation of sex reversal while 5-HT inhibits both initiation and completion of sex reversal. The serotonergic system appears to be an integral part of the pathway mediating the conversion of a social cue into a neuroendocrine event. The complex organization of neurochemical events controlling the psychosocial, physiological, and anatomical events that constitute reversal of sexual identity includes monoamine neurotransmitters.

The evaluation of preprocessing choices in single-subject BOLD fMRI using NPAIRS performance metrics

This work proposes an alternative to simulation-based receiver operating characteristic (ROC) analysis for assessment of fMRI data analysis methodologies. Specifically, we apply the rapidly developing nonparametric prediction, activation, influence, and reproducibility resampling (NPAIRS) framework to obtain cross-validation-based model performance estimates of prediction accuracy and global reproducibility for various degrees of model complexity. We rely on the concept of an analysis chain meta-model in which all parameters of the preprocessing steps along with the final statistical model are treated as estimated model parameters. Our ROC analog, then, consists of plotting prediction vs. reproducibility results as curves of model complexity for competing meta-models. Two theoretical underpinnings are crucial to utilizing this new validation technique. First, we explore the relationship between global signal-to-noise and our reproducibility estimates as derived previously. Second, we submit our model complexity curves in the prediction versus reproducibility space as reflecting classic bias-variance tradeoffs. Among the particular analysis chains considered, we found little impact in performance metrics with alignment, some benefit with temporal detrending, and greatest improvement with spatial smoothing.

Time-frequency spectral estimation of multichannel EEG using the Auto-SLEX method

In this paper, we apply a new time-frequency spectral estimation method for multichannel data to epileptiform electroencephalography (EEG). The method is based on the smooth localized complex exponentials (SLEX) functions which are time-frequency localized versions of the Fourier functions and, hence, are ideal for analyzing nonstationary signals whose spectral properties evolve over time. The SLEX functions are simultaneously orthogonal and localized in time and frequency because they are obtained by applying a projection operator rather than a window or taper. In this paper, we present the Auto-SLEX method which is a statistical method that 1) computes the periodogram using the SLEX transform, 2) automatically segments the signal into approximately stationary segments using an objective criterion that is based on log energy, and 3) automatically selects the optimal bandwidth of the spectral smoothing window. The method is applied to the intracranial EEG from a patient with temporal lobe epilepsy. This analysis reveals a reduction in average duration of stationarity in preseizure epochs of data compared to baseline. These changes begin up to hours prior to electrical seizure onset in this patient.

Davidson Trauma Scale (DTS): normative scores in the general population and effect sizes in placebo-controlled SSRI trials

The Davidson Trauma Scale (DTS) was developed as a self-rating for use in diagnosing and measuring symptom severity and treatment outcome in post-traumatic stress disorder (PTSD); 630 subjects were identified by random digit dialing and evaluated for a history of trauma. Prevalence rates of PTSD and subthreshold PTSD with impairment were 2.2 and 4.1%, respectively. In this general population sample, 438 subjects endorsed at least one trauma, and four groups were generated: A) threshold PTSD (n = 13), B) subthreshold PTSD with impairment (n = 26), C) subthreshold PTSD without impairment (n = 78), and D) no PTSD (n = 321). Mean (SD) DTS score in the entire population was 11.0 +/- 18.1. Differences were found in four of the five pairwise between-group contrasts. In a second sample of 447 clinical trial participants from three SSRI vs. placebo studies, we assessed treatment effect size according to different measures. In all three clinical trials, effect size with the DTS was equal to, or better than, those found for the Impact of Event Scale (IES), Clinician Administered PTSD Scale (CAPS), and Structured Interview for PTSD (SIP). These results further affirm the utility of the DTS as a self-rating measure of PTSD symptom severity and in evaluating treatment response.

Prediction of epileptic seizures

For almost 40 years, neuroscientists thought that epileptic seizures began abruptly, just a few seconds before clinical attacks. There is now mounting evidence that seizures develop minutes to hours before clinical onset. This change in thinking is based on quantitative studies of long digital intracranial electroencephalographic (EEG) recordings from patients being evaluated for epilepsy surgery. Evidence that seizures can be predicted is spread over diverse sources in medical, engineering, and patent publications. Techniques used to forecast seizures include frequency-based methods, statistical analysis of EEG signals, non-linear dynamics (chaos), and intelligent engineered systems. Advances in seizure prediction promise to give rise to implantable devices able to warn of impending seizures and to trigger therapy to prevent clinical epileptic attacks. Treatments such as electrical stimulation or focal drug infusion could be given on demand and might eliminate side-effects in some patients taking antiepileptic drugs long term. Whether closed-loop seizure-prediction and treatment devices will have the profound clinical effect of their cardiological predecessors will depend on our ability to perfect these techniques. Their clinical efficacy must be validated in large-scale, prospective, controlled trials.

The quantitative evaluation of functional neuroimaging experiments: the NPAIRS data analysis framework

We introduce a data-analysis framework and performance metrics for evaluating and optimizing the interaction between activation tasks, experimental designs, and the methodological choices and tools for data acquisition, preprocessing, data analysis, and extraction of statistical parametric maps (SPMs). Our NPAIRS (nonparametric prediction, activation, influence, and reproducibility resampling) framework provides an alternative to simulations and ROC curves by using real PET and fMRI data sets to examine the relationship between prediction accuracy and the signal-to-noise ratios (SNRs) associated with reproducible SPMs. Using cross-validation resampling we plot training-test set predictions of the experimental design variables (e.g., brain-state labels) versus reproducibility SNR metrics for the associated SPMs. We demonstrate the utility of this framework across the wide range of performance metrics obtained from [(15)O]water PET studies of 12 age- and sex-matched data sets performing different motor tasks (8 subjects/set). For the 12 data sets we apply NPAIRS with both univariate and multivariate data-analysis approaches to: (1) demonstrate that this framework may be used to obtain reproducible SPMs from any data-analysis approach on a common Z-score scale (rSPM[Z]); (2) demonstrate that the histogram of a rSPM[Z] image may be modeled as the sum of a data-analysis-dependent noise distribution and a task-dependent, Gaussian signal distribution that scales monotonically with our reproducibility performance metric; (3) explore the relation between prediction and reproducibility performance metrics with an emphasis on bias-variance tradeoffs for flexible, multivariate models; and (4) measure the broad range of reproducibility SNRs and the significant influence of individual subjects. A companion paper describes learning curves for four of these 12 data sets, which describe an alternative mutual-information prediction metric and NPAIRS reproducibility as a function of training-set sizes from 2 to 18 subjects. We propose the NPAIRS framework as a validation tool for testing and optimizing methodological choices and tools in functional neuroimaging.

The impact of borderline personality disorder on post-traumatic stress in the community: a study of health status, health utilization, and functioning

This study examines impairment and health status and resource utilization among individuals with and without borderline personality disorder (BPD), all of whom had post-traumatic stress symptoms (PTSS). Using data from the community-based Piedmont Health Survey, 150 adult respondents who had experienced clinically significant PTSS during their life were identified. The Diagnostic Interview Schedule (DIS) Borderline Index was used to distinguish a subset of respondents who met criteria for BPD. Compared with adults with PTSS (n = 135), individuals with PTSS and BPD (PTSS-BPD) (n = 15) exhibited impaired health status and greater utilization of mental health services and psychotropic medications, as well as more functional impairment based on social, occupational, and early adverse life-event measures. Individuals with comorbid PTSS and BPD demonstrate greater overall impairment and usage of health care resources.

Can the checklist for autism in toddlers differentiate young children with autism from those with developmental delays?

OBJECTIVE

The Checklist for Autism in Toddlers (CHAT) has been demonstrated to be sensitive to the presence of autism in otherwise normally developing 18-month-old children. However, its ability to differentiate autism from other significant developmental delays is unknown. This study examined this question.

METHOD

The CHAT was applied to a group of 44 children aged 2 and 3 years, rigorously diagnosed with autism or with other developmental problems.

RESULTS

By the original CHAT authors' criteria, the sensitivity and specificity of the CHAT were 65% and 100%, respectively. Slightly altering the criteria resulted in a sensitivity of 85% in the current group of children with developmental disabilities while maintaining specificity of 100%.

CONCLUSIONS

The current study is the first to demonstrate that the CHAT successfully discriminates 2-year-old children with autism from those with other developmental disorders. In addition, the increased sensitivity of the Denver Criteria in children with developmental disabilities may improve its usefulness as a screening tool for community-based early-diagnostic teams and general practitioners.

Alcohol abuse or dependence among Mexican American women who report violence

BACKGROUND

Violence against women has been linked to alcohol disorders in various populations. Few studies have assessed alcohol disorders among assaulted women in a general population of Mexican Americans. This study examined alcohol disorders among Mexican American women who reported physical or sexual assault.

METHODS

Participants were women (n = 1516, ages 18-59) living in Fresno County, California, who were enrolled in a population-based, randomized household survey of Mexican-origin men and women. Crude and adjusted odds ratios (ORs) were calculated for alcohol dependence/abuse (ADA) and physical or sexual assault by a current partner or someone other than a current partner.

RESULTS

Women who reported lifetime physical or sexual assault were significantly more likely to meet criteria for ADA (OR = 8.2; 95% confidence interval [CI], 4.4-15.4). After we adjusted for birthplace, age, income, and parental problem drinking, assaulted women were still 4.7 times more likely to meet criteria for ADA (CI, 2.1-10.4). Physical or sexual assault by someone other than a partner was more strongly associated with ADA (OR = 8.7; CI, 4.5-16.9) than assault by a current partner (OR = 3.2; CI, 1.3-7.6). Both physical (OR = 9.0; CI, 4.7-17.0) and sexual assault (OR = 4.7; CI, 2.2-10.0) by either type of perpetrator were associated with ADA.

CONCLUSION

There is a strong association between reporting violence and having a lifetime history of ADA. Although temporal order could not be established, these findings highlight the importance of screening for physical and sexual assault in settings that treat alcohol disorders as well as screening for alcohol disorders among women who seek services related to previous or current violence.

Translating developmental time across mammalian species

Conservation of the order in which events occur in developing mammalian brains permits use of regression theory to model the timing of neural development. Following a small adjustment to account for a systematic variability in primate cortical and limbic systems, the model is used to generate a 95-event/nine-species matrix that predicts aspects of neurogenesis and axonal outgrowth in the brains of developing mice, hamsters, rats, spiny mice, rabbits, ferrets, cats, monkeys, and humans. Although data are compiled from species in which the timing of birth and the rate of maturation vary widely, the model proves statistically accurate, with practical implications for improving estimation of milestones of neural development, particularly for humans. Using the three-factor model (species, neural events, and primate adjustments), we produce predictions for the timing of 493 neural occurrences in developing mammalian brains that either have not yet been, or cannot be, empirically derived. We also relate the timing of neural events across the nine species in the form of a reference table calibrated to the development of laboratory rats. This 'translation' table will assist in attempts to equate the neurodevelopmental literature across species with either large or small differences in gestation and maturation, and also permit studies done in a variety of mammals to be applied to better understand human development. The comparative data indicate that humans, although conventionally considered an altricial species, are neurally advanced at birth relative to the other species studied.

Using biological indices to classify schizophrenia and other psychotic patients

Although classification of mental disorders using more than clinical description would be desirable, there is scant evidence that available laboratory tests (i.e. biological indices) would provide more valid classifications than current diagnostic systems (e.g. DSM-IV). We used cluster analysis of four biological variables to classify 163 psychotic patients and 83 nonpsychiatric comparison subjects. Analyses revealed a three-cluster solution with the first cluster reflecting electrodermal deviance, the second cluster representing nondeviant biological function, and the third cluster reflecting increased nailfold plexus visibility and ocular motor dysfunction. To assess the construct validity of proband clusters we examined ocular motor performance in 156 first-degree relatives as a function of proband cluster membership. First-degree relatives of third cluster probands exhibited worse ocular motor performance than relatives of other cluster probands. Additionally, better classification sensitivity and specificity were obtained for the relatives when they were grouped by proband cluster than by proband DSM-IV diagnosis. When a single proband characteristic (i.e. eyetracking performance) was used to group relatives, classification sensitivity and specificity failed to significantly increase over grouping by proband DSM-IV diagnosis. Multivariate biologically defined clusters may offer an advantage over DSM-IV classification when examining nosology and etiology of psychotic disorders.

Suppression, repressive-defensiveness, restraint, and distress in metastatic breast cancer: separable or inseparable constructs?

A longstanding hypothesis links affective and behavioral inhibition with cancer incidence and progression though it does not clarify psychometric distinctions among related constructs. We hypothesized that repressive-defensiveness, suppression, restraint, and distress would be separable factors in our sample of metastatic breast cancer patients. Our results support the discriminant validity of these constructs in our total sample, and the stability over 1 year in our control group. Using factor analysis, we found 4 separate factors at our prerandomization baseline corresponding closely to hypothesized constructs. Additionally, associations in a multi-trait, multi-occasion (baseline and 1 year) matrix met each of the 3 Campbell and Fiske (1959) criteria of convergent and discriminant validity. Future research testing the links between psychological, physiological, and survival outcomes with affective inhibition in cancer patients will be clearer when informed by these distinctions.

Neuronal correlates of motor performance and motor learning in the primary motor cortex of monkeys adapting to an external force field

The primary motor cortex (M1) is known to control motor performance. Recent findings have also implicated M1 in motor learning, as neurons in this area show learning-related plasticity. In the present study, we analyzed the neuronal activity recorded in M1 in a force field adaptation task. Our goal was to investigate the neuronal reorganization across behavioral epochs (before, during, and after adaptation). Here we report two main findings. First, memory cells were present in two classes. With respect to the changes of preferred direction (Pd), these two classes complemented each other after readaptation. Second, for the entire neuronal population, the shift of Pd matched the shift observed for muscles. These results provide a framework whereby the activity of distinct neuronal subpopulations combines to subserve both functions of motor performance and motor learning.

Intimate partner violence and health: self-assessed health, chronic health, and somatic symptoms among Mexican American women

OBJECTIVE

In medical settings intimate partner violence (IPV) has been linked to a variety of health problems. However, few population-based studies have assessed the health of abused women, particularly women from low socioeconomic groups such as Mexican Americans. This study examined the association between recent physical or sexual IPV and self-rated health, chronic health conditions, and somatic symptoms among Mexican American women.

METHODS

Participants were women (N = 1155) with current male partners enrolled in a household survey of 3012 Mexican-origin adults, ages 18 to 59 years, living in urban, town, and rural areas of Fresno County, California. Crude and adjusted odds ratios (ORs) were calculated for four self-assessed health measures, seven chronic diseases, and 32 somatic symptoms.

RESULTS

In multivariate analyses, women reporting previous-year physical or sexual IPV were more likely to report 1) fair/poor overall health (OR, 1.9; confidence interval [CI], 1.0-3.7), physical health (OR, 2.1; CI, 1.2-3.9), and mental health (OR, 3.4; CI, 1.9-6.1), as well as worse comparative health (OR, 4.4; CI, 2.3-8.3); 2) a history of heart problems (OR, 17.0; CI, 4.3-66.7); 3) persistent health problems (OR, 3.3; CI, 1.5-7.0); and 4) numerous somatic symptoms.

CONCLUSIONS

Physical or sexual IPV was associated with poorer self-assessed health and many health symptoms among this culturally distinctive Mexican American population.

Developmental structure in brain evolution

How does evolution grow bigger brains? It has been widely assumed that growth of individual structures and functional systems in response to niche-specific cognitive challenges is the most plausible mechanism for brain expansion in mammals. Comparison of multiple regressions on allometric data for 131 mammalian species, however, suggests that for 9 of 11 brain structures taxonomic and body size factors are less important than covariance of these major structures with each other. Which structure grows biggest is largely predicted by a conserved order of neurogenesis that can be derived from the basic axial structure of the developing brain. This conserved order of neurogenesis predicts the relative scaling not only of gross brain regions like the isocortex or mesencephalon, but also the level of detail of individual thalamic nuclei. Special selection of particular areas for specific functions does occur, but it is a minor factor compared to the large-scale covariance of the whole brain. The idea that enlarged isocortex could be a "spandrel," a by-product of structural constraints later adapted for various behaviors, contrasts with approaches to selection of particular brain regions for cognitively advanced uses, as is commonly assumed in the case of hominid brain evolution.