Fully integrated silicon probes for high-density recording of neural activity.

Sensory, motor and cognitive operations involve the coordinated action of large neuronal populations across multiple brain regions in both superficial and deep structures. Existing extracellular probes record neural activity with excellent spatial and temporal (sub-millisecond) resolution, but from only a few dozen neurons per shank. Optical Ca2+ imaging offers more coverage but lacks the temporal resolution needed to distinguish individual spikes reliably and does not measure local field potentials. Until now, no technology compatible with use in unrestrained animals has combined high spatiotemporal resolution with large volume coverage. Here we design, fabricate and test a new silicon probe known as Neuropixels to meet this need. Each probe has 384 recording channels that can programmably address 960 complementary metal-oxide-semiconductor (CMOS) processing-compatible low-impedance TiN sites that tile a single 10-mm long, 70 × 20-µm cross-section shank. The 6 × 9-mm probe base is fabricated with the shank on a single chip. Voltage signals are filtered, amplified, multiplexed and digitized on the base, allowing the direct transmission of noise-free digital data from the probe. The combination of dense recording sites and high channel count yielded well-isolated spiking activity from hundreds of neurons per probe implanted in mice and rats. Using two probes, more than 700 well-isolated single neurons were recorded simultaneously from five brain structures in an awake mouse. The fully integrated functionality and small size of Neuropixels probes allowed large populations of neurons from several brain structures to be recorded in freely moving animals. This combination of high-performance electrode technology and scalable chip fabrication methods opens a path towards recording of brain-wide neural activity during behaviour.

Midlife women's cardiovascular symptoms: A cluster analysis.

Menopausal transition, in which biological and psychosocial changes are caused due to estrogen fluctuations, has been reported to increase cardiovascular risk among midlife women. The purposes of this study were to identify the clusters of midlife women by cardiovascular symptoms and to examine racial/ethnic differences in the clusters. This was a secondary analysis, in which hierarchical cluster and multinomial logistic analyses were conducted with the data (N = 966) collected in two previous studies. Three clusters were adopted: Cluster 1 (high vasomotor and low cardiorespiratory), Cluster 2 (low vasomotor and high cardiorespiratory and high discomfort/pain), and Cluster 3 (high discomfort/pain and high indigestion).

Active sensing associated with spatial learning reveals memory-based attention in an electric fish.

Active sensing behaviors reveal what an animal is attending to and how it changes with learning. Gymnotus sp, a gymnotiform weakly electric fish, generates an electric organ discharge (EOD) as discrete pulses to actively sense its surroundings. We monitored freely behaving gymnotid fish in a large dark "maze" and extracted their trajectories and EOD pulse pattern and rate while they learned to find food with electrically detectable landmarks as cues. After training, they more rapidly found food using shorter, more stereotyped trajectories and spent more time near the food location. We observed three forms of active sensing: sustained high EOD rates per unit distance (sampling density), transient large increases in EOD rate (E-scans) and stereotyped scanning movements (B-scans) were initially strong at landmarks and food, but, after learning, intensified only at the food location. During probe (no food) trials, after learning, the fish's search area and intense active sampling was still centered on the missing food location, but now also increased near landmarks. We hypothesize that active sensing is a behavioral manifestation of attention and essential for spatial learning; the fish use spatial memory of landmarks and path integration to reach the expected food location and confine their attention to this region.

Informing hot flash treatment decisions for breast cancer survivors: a systematic review of randomized trials comparing active interventions.

Patient-centered decision making about hot flash treatments often incorporates a balance of efficacy and side effects in addition to patient preference. This systematic review examines randomized controlled trials (RCTs) comparing at least two non-hormonal hot flash treatments in breast cancer survivors. In July 2015, PubMed, SCOPUS, CINAHL, Cochrane, and Web of Science databases were searched for RCTs comparing active, non-hormonal hot flash treatments in female breast cancer survivors. Thirteen trials were included after identifying 906 potential studies. Four trials were dose comparison studies of pharmacologic treatments citalopram, venlafaxine, gabapentin, and paroxetine. Hot flash reduction did not differ by tamoxifen or aromatase inhibitor use. Citalopram 10, 20, and 30 mg daily had comparable outcomes. Venlafaxine 75 mg daily improved hot flashes without additional side effects from higher dosing. Gabapentin 900 mg daily improved hot flashes more than 300 mg. Paroxetine 10 mg daily had fewer side effects than 20 mg. Among four trials comparing different pharmacologic treatments, venlafaxine alleviated hot flash symptoms faster than clonidine; participants preferred venlafaxine over gabapentin. Five trials compared pharmacologic to non-pharmacologic treatments. Acupuncture had similar efficacy to venlafaxine and gabapentin but may have longer durability after completing treatment and fewer side effects. We could not perform a pooled meta-analysis because outcomes were not reported in comparable formats. Clinical trial data on non-hormonal hot flash treatments provide comparisons of hot flash efficacy and other patient important outcomes to guide clinical management. Clinicians can use the information to help patients select hot flash interventions.

Issues in Developing and Evaluating a Culturally Tailored Internet Cancer Support Group.

The purpose of this article is to explore practical issues in developing and implementing a culturally tailored Internet Cancer Support Group for a group of ethnic minority patients with cancer-Asian Americans. Throughout the research process of the original study testing the Internet cancer support group, the research team made written records of practical issues and plausible rationales for the issues. Weekly group discussion among research team members was conducted, and the discussion records were evaluated and analyzed using a content analysis (with individual words as the unit of analysis). The codes from the analysis process were categorized into idea themes, through which the issues were extracted. The issues included those in (1) difficulties in using multiple languages, (2) collaboration with the information technology department and technical challenges, (3) difficulties in recruitment, (4) difficulties in retention, (5) optimal timing, and (6) characteristics of the users. Based on the findings, we suggest that researchers plan a workable translation process, check technical needs in advance, use multiple strategies to recruit and retain research participants, plan the right time for data collection, and consider characteristics of the users in the study design.

Immigration transition and depressive symptoms: four major ethnic groups of midlife women in the United States.

The purpose of this study was to explore the relationships between immigration transition and depressive symptoms among 1,054 midlife women in the United States. This was a secondary analysis of the data from two national Internet survey studies. Questions on background characteristics and immigration transition and the Depression Index for Midlife Women were used to collect the data. The data were analyzed using inferential statistics including multiple regressions. Immigrants reported lower numbers of symptoms and less severe symptoms than nonimmigrants (p <.01). When controlling for background characteristics, self-reported racial/ethnic identity and immigration status were significant predictors of depressive symptoms (R(2) =.01, p <.05).

Enhanced sensory sampling precedes self-initiated locomotion in an electric fish.

Cortical activity precedes self-initiated movements by several seconds in mammals; this observation has led into inquiries on the nature of volition. Preparatory neural activity is known to be associated with decision making and movement planning. Self-initiated locomotion has been linked to increased active sensory sampling; however, the precise temporal relationship between sensory acquisition and voluntary movement initiation has not been established. Based on long-term monitoring of sensory sampling activity that is readily observable in freely behaving pulse-type electric fish, we show that heightened sensory acquisition precedes spontaneous initiation of swimming. Gymnotus sp. revealed a bimodal distribution of electric organ discharge rate (EODR) demonstrating down- and up-states of sensory sampling and neural activity; movements only occurred during up-states and up-states were initiated before movement onset. EODR during voluntary swimming initiation exhibited greater trial-to-trial variability than the sound-evoked increases in EODR. The sampling variability declined after voluntary movement onset as previously observed for the neural variability associated with decision making in primates. Spontaneous movements occurred randomly without a characteristic timescale, and no significant temporal correlation was found between successive movement intervals. Using statistical analyses of spontaneous exploratory behaviours and associated preparatory sensory sampling increase, we conclude that electric fish exhibit key attributes of volitional movements, and that voluntary behaviours in vertebrates may generally be preceded by increased sensory sampling. Our results suggest that comparative studies of the neural basis of volition may therefore be possible in pulse-type electric fish, given the substantial homologies between the telencephali of teleost fish and mammals.

A pilot study of audio-visual stimulation as a self-care treatment for insomnia in adults with insomnia and chronic pain.

This pilot study tested the efficacy of an audio-visual stimulation (AVS) program for the promotion of sleep in individuals with chronic pain. Insomnia and chronic pain are common comorbid conditions and their relationship has been viewed as bidirectional. Recent studies suggest a relatively dominant role of sleep in this dyad. The premise of this pilot study was that AVS enhances low frequency while reducing high frequency brain activity resulting in decreased hyperarousal and improved sleep with potential consequent reduction in pain. We conducted a pilot intervention study of AVS using a pre-post design. Participants self-administered a 30-min AVS program nightly at bedtime for 1 month. Sleep and pain were assessed at baseline and at the conclusion of the 4-week intervention phase. Nine adults (mean age 33 ± 15.8 years; female, 89 %) completed the study. After using the AVS device for 4 weeks, significant improvement was seen in reported insomnia (ISI, p = 0.003), pain severity (BPI, p = 0.005), and pain interference with functioning (BPI, p = 0.001). Large effect sizes (Partial η(2) 0.20-0.94) (Cohen's d 0.44-1.45) were observed. The results of this pilot study suggest that the AVS program may be efficacious in decreasing both insomnia and pain symptoms. In order to better assess the efficacy of AVS for sleep promotion and possible pain reduction, more definitive randomized controlled trials will be needed. These should include appropriate sample sizes, objective measures of sleep and pain, and longitudinal follow-up.

Tai chi for well-being of breast cancer survivors with aromatase inhibitor-associated arthralgias: a feasibility study.

CONTEXT: Arthralgia is common and debilitating for a significant proportion of breast cancer survivors (BCSs) and leads to poor adherence to aromatase inhibitors (AIs). Despite increased recognition of the negative impact of arthralgia on function and the poor adherence that results, very few interventions have been developed to target this side effect. OBJECTIVE: This study aimed to determine the feasibility of tai chi to improve well-being for women experiencing AI-associated arthralgias (AIAAs). DESIGN: The study was a pilot to (1) demonstrate the feasibility of recruitment and retention for a tai chi trial, (2) determine the safety of tai chi, and (3) identify the outcomes (function, pain, and quality of life[QOL]) that tai chi may impact. SETTING: The study took place at the Gilda's Club South Jersey in Linwood, NJ, USA. PARTICIPANTS: Postmenopausal women with a history of stage I-III breast cancer reporting AIAA were enrolled. INTERVENTION: Group tai chi was practiced for 1 h 2 ×/wk for 8 wks. OUTCOME MEASURES: Functional outcomes included (1) sit-and-reach (SR), (2) functional reach (FR), (3) the Berg Balance Scale (BBS), and (4) timed up-and-go (TUG). The following patient-reported outcomes (PROs) were evaluated pre- and postintervention: (1) the Hospital Anxiety and Depression Scale (HADS), (2) the Functional Assessment of Cancer Therapy-Breast (FACT-B), (3) the Functional Assessment of Chronic Illness Therapy Fatigue (FACIT-Fatigue), (4) the Brief Pain Inventory (BPI), (5) the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT-GOG-Ntx), and (6) the Functional Assessment of Chronic Illness Therapy- Spiritual Well-being Scale (FACIT-Sp). Participants also recorded their tai chi experiences in a journal. RESULTS: For the 12 participants, adherence to the classes was 75%, with no adverse events reported. Participants experienced significant improvement from baseline to follow-up for the HADS anxiety (P = .003) and depression (P = .020) scales, the emotional well-being scale of the FACT-B (P = .027), the FACIT-Fatigue (P = .030), and the sit-and-teach test (P = .016). The BBS (P = .090), TUG (P = .241), BPI severity subscale (P = .058), and physical well-being subscale of the FACT-B (P = .052) showed no significant improvement. Participants reported increased relaxation, reduced stress, and enhanced sleep quality and duration. They valued the group's and the instructor's support. CONCLUSION: The research team demonstrated the feasibility of a tai chi intervention for improving wellbeing for breast cancer patients with AIAA and identified measures that may be sensitive to the impact of a tai chi intervention in this population.

Precision measurement of electric organ discharge timing from freely moving weakly electric fish.

Physiological measurements from an unrestrained, untethered, and freely moving animal permit analyses of neural states correlated to naturalistic behaviors of interest. Precise and reliable remote measurements remain technically challenging due to animal movement, which perturbs the relative geometries between the animal and sensors. Pulse-type electric fish generate a train of discrete and stereotyped electric organ discharges (EOD) to sense their surroundings actively, and rapid modulation of the discharge rate occurs while free swimming in Gymnotus sp. The modulation of EOD rates is a useful indicator of the fish's central state such as resting, alertness, and learning associated with exploration. However, the EOD pulse waveforms remotely observed at a pair of dipole electrodes continuously vary as the fish swims relative to the electrodes, which biases the judgment of the actual pulse timing. To measure the EOD pulse timing more accurately, reliably, and noninvasively from a free-swimming fish, we propose a novel method based on the principles of waveform reshaping and spatial averaging. Our method is implemented using envelope extraction and multichannel summation, which is more precise and reliable compared with other widely used threshold- or peak-based methods according to the tests performed under various source-detector geometries. Using the same method, we constructed a real-time electronic pulse detector performing an additional online pulse discrimination routine to enhance further the detection reliability. Our stand-alone pulse detector performed with high temporal precision (<10 µs) and reliability (error <1 per 10(6) pulses) and permits longer recording duration by storing only event time stamps (4 bytes/pulse).

Chamomile (Matricaria recutita) may provide antidepressant activity in anxious, depressed humans: an exploratory study.

CONTEXT: Anxiety and depression are the most commonly reported psychiatric conditions and frequently occur as comorbid disorders. While the advent of conventional drug therapies has simplified treatment, a large segment of the population goes untreated or declines conventional therapy for financial, cultural, or personal reasons. Therefore, the identification of inexpensive and effective alternative therapies for anxiety and depression is of relevance to public health. OBJECTIVE: The current study explores data from a 2009 clinical chamomile trial in humans to determine if chamomile provides clinically meaningful antidepressant activity versus a placebo. DESIGN: In the 2009 randomized, double-blind, placebo-controlled study, the research team examined the antianxiety and antidepressant action of oral chamomile (Matricaria recutita) extract in participants with symptoms of comorbid anxiety and depression. SETTING: In the 2009 study, all of participants' evaluations took place at the Depression Research Unit at the University of Pennsylvania. The study drew participants from patients at the Department of Family Medicine and Community Health's primary care clinic at the University of Pennsylvania, Philadelphia. PARTICIPANTS: Of the 57 participants in the 2009 trial, 19 had anxiety with comorbid depression; 16 had anxiety with a past history of depression; and 22 had anxiety with no current or past depression. INTERVENTION: The intervention and placebo groups in the 2009 trial received identically appearing 220-mg capsules containing either pharmaceutical-grade chamomile extract standardized to a content of 1.2% apigenin or a placebo (ie, lactose monohydrate NF), respectively. OUTCOME MEASURES: In the current study, the research team used generalized estimating equations analysis to identify clinically meaningful changes over time in scores from the Hamilton Depression Rating (HAM-D) questionnaire among treatment groups. RESULTS: In the current study, the research team observed a significantly greater reduction over time in total HAM-D scores for chamomile vs placebo in all participants (P < .05). The team also observed a clinically meaningful but nonsignificant trend for a greater reduction in total HAM-D scores for chamomile vs placebo in participants with current comorbid depression (P = .062). When the team examined the HAM-D core mood item scores, it observed a significantly greater reduction over time for chamomile vs placebo in all participants (P < .05) and a clinically meaningful but nonsignificant trend for a greater reduction over time for chamomile vs placebo in participants without current or past depression (P = .06). CONCLUSION: Chamomile may provide clinically meaningful antidepressant activity that occurs in addition to its previously observed anxiolytic activity.

High-density neural recordings from feline sacral dorsal root ganglia with thin-film array.

Objective. Dorsal root ganglia (DRG) are promising sites for recording sensory activity. Current technologies for DRG recording are stiff and typically do not have sufficient site density for high-fidelity neural data techniques.Approach. In acute experiments, we demonstrate single-unit neural recordings in sacral DRG of anesthetized felines using a 4.5µm thick, high-density flexible polyimide microelectrode array with 60 sites and 30-40µm site spacing. We delivered arrays into DRG with ultrananocrystalline diamond shuttles designed for high stiffness affording a smaller footprint. We recorded neural activity during sensory activation, including cutaneous brushing and bladder filling, as well as during electrical stimulation of the pudendal nerve and anal sphincter. We used specialized neural signal analysis software to sort densely packed neural signals.Main results. We successfully delivered arrays in five of six experiments and recorded single-unit sensory activity in four experiments. The median neural signal amplitude was 55µV peak-to-peak and the maximum unique units recorded at one array position was 260, with 157 driven by sensory or electrical stimulation. In one experiment, we used the neural analysis software to track eight sorted single units as the array was retracted ∼500µm.Significance. This study is the first demonstration of ultrathin, flexible, high-density electronics delivered into DRG, with capabilities for recording and tracking sensory information that are a significant improvement over conventional DRG interfaces.

SpikeForest, reproducible web-facing ground-truth validation of automated neural spike sorters.

Spike sorting is a crucial step in electrophysiological studies of neuronal activity. While many spike sorting packages are available, there is little consensus about which are most accurate under different experimental conditions. SpikeForest is an open-source and reproducible software suite that benchmarks the performance of automated spike sorting algorithms across an extensive, curated database of ground-truth electrophysiological recordings, displaying results interactively on a continuously-updating website. With contributions from eleven laboratories, our database currently comprises 650 recordings (1.3 TB total size) with around 35,000 ground-truth units. These data include paired intracellular/extracellular recordings and state-of-the-art simulated recordings. Ten of the most popular spike sorting codes are wrapped in a Python package and evaluated on a compute cluster using an automated pipeline. SpikeForest documents community progress in automated spike sorting, and guides neuroscientists to an optimal choice of sorter and parameters for a wide range of probes and brain regions.

Randomized, double-blind, placebo-controlled trial of Cimicifuga racemosa (black cohosh) in women with anxiety disorder due to menopause.

OBJECTIVE: We conducted a randomized, double-blind, placebo-controlled, parallel group trial of the efficacy and tolerability of Cimicifuga racemosa (black cohosh) extract for the treatment of anxiety disorder due to menopause. We hypothesized that black cohosh would be superior to placebo in reducing anxiety symptoms of menopause, with a comparable tolerability profile to placebo. MATERIALS AND METHODS: Subjects were randomized to therapy with either pharmaceutical-grade black cohosh extract (n = 15) or placebo (n = 13) for up to 12 weeks. The primary outcome measure was changed over time in total Hamilton Anxiety Rating Scale (HAM-A) scores. Secondary outcomes included a change in scores on the Beck Anxiety Inventory, Green Climacteric Scale (GCS), and Psychological General Well-Being Index (PGWBI) and the proportion of patients with a change of 50% or higher in baseline HAM-A scores. RESULTS: There was neither a significant group difference in change over time in total HAM-A scores (P = 0.294) nor a group difference in the proportion of subjects with a reduction of 50% or higher in baseline HAM-A scores at study end point (P = 0.79). There was a significantly greater reduction in the total GCS scores during placebo (vs black cohosh; P = 0.035) but no group difference in change over time in the GCS subscale scores or in the PGWBI (P = 0.140). One subject (3.6%) taking black cohosh discontinued treatment because of adverse events. CONCLUSIONS: We found no statistically significant anxiolytic effect of black cohosh (vs placebo). However, small sample size, choice of black cohosh preparation, and dosage used may have been limiting factors producing negative results.

A randomized, double-blind, placebo-controlled trial of oral Matricaria recutita (chamomile) extract therapy for generalized anxiety disorder.

OBJECTIVE: We conducted a randomized, double-blind, placebo-controlled efficacy and tolerability trial of Matricaria recutita (chamomile) extract therapy in patients with mild to moderate generalized anxiety disorder (GAD). We hypothesized that chamomile would be superior to placebo in reducing GAD symptoms with a comparable tolerability profile. MATERIALS AND METHODS: Sixty-one outpatients with mild to moderate GAD were enrolled, and 57 were randomized to either double-blind chamomile extract (n = 28) or placebo therapy (n = 29) for 8 weeks. The study was powered to detect a statistically significant and clinically meaningful group difference in change over time in total Hamilton Anxiety Rating (HAM-A) scores. Secondary outcomes included change in the Beck Anxiety Inventory, Psychological Well Being, and Clinical Global Impression Severity scores and the proportion of patients with 50% reduction or more in baseline HAM-A score. RESULTS: We observed a significantly greater reduction in mean total HAM-A score during chamomile versus placebo therapy (P = 0.047). Although the study was not powered to identify small to moderate differences in secondary outcomes, we observed a positive change in all secondary outcomes in the same direction as the primary outcome measure. One patient in each treatment group discontinued therapy for adverse events. The proportion of patients experiencing 0, 1, 2, or 3 adverse events or more was not significantly different between groups (P = 0.417). CONCLUSIONS: This is the first controlled clinical trial of chamomile extract for GAD. The results suggest that chamomile may have modest anxiolytic activity in patients with mild to moderate GAD. Future studies are needed to replicate these observations.

Therapeutic uses of magnesium.

Magnesium is an essential mineral for optimal metabolic function. Research has shown that the mineral content of magnesium in food sources is declining, and that magnesium depletion has been detected in persons with some chronic diseases. This has led to an increased awareness of proper magnesium intake and its potential therapeutic role in a number of medical conditions. Studies have shown the effectiveness of magnesium in eclampsia and preeclampsia, arrhythmia, severe asthma, and migraine. Other areas that have shown promising results include lowering the risk of metabolic syndrome, improving glucose and insulin metabolism, relieving symptoms of dysmenorrhea, and alleviating leg cramps in women who are pregnant. The use of magnesium for constipation and dyspepsia are accepted as standard care despite limited evidence. Although it is safe in selected patients at appropriate dosages, magnesium may cause adverse effects or death at high dosages. Because magnesium is excreted renally, it should be used with caution in patients with kidney disease. Food sources of magnesium include green leafy vegetables, nuts, legumes, and whole grains.

Neural activity in a hippocampus-like region of the teleost pallium is associated with active sensing and navigation.

Most vertebrates use active sensing strategies for perception, cognition and control of motor activity. These strategies include directed body/sensor movements or increases in discrete sensory sampling events. The weakly electric fish, Gymnotus sp., uses its active electric sense during navigation in the dark. Electric organ discharge rate undergoes transient increases during navigation to increase electrosensory sampling. Gymnotus also use stereotyped backward swimming as an important form of active sensing that brings objects toward the electroreceptor dense fovea-like head region. We wirelessly recorded neural activity from the pallium of freely swimming Gymnotus. Spiking activity was sparse and occurred only during swimming. Notably, most units tended to fire during backward swims and their activity was on average coupled to increases in sensory sampling. Our results provide the first characterization of neural activity in a hippocampal (CA3)-like region of a teleost fish brain and connects it to active sensing of spatial environmental features.

A time-stamp mechanism may provide temporal information necessary for egocentric to allocentric spatial transformations.

Learning the spatial organization of the environment is essential for most animals' survival. This requires the animal to derive allocentric spatial information from egocentric sensory and motor experience. The neural mechanisms underlying this transformation are mostly unknown. We addressed this problem in electric fish, which can precisely navigate in complete darkness and whose brain circuitry is relatively simple. We conducted the first neural recordings in the preglomerular complex, the thalamic region exclusively connecting the optic tectum with the spatial learning circuits in the dorsolateral pallium. While tectal topographic information was mostly eliminated in preglomerular neurons, the time-intervals between object encounters were precisely encoded. We show that this reliable temporal information, combined with a speed signal, can permit accurate estimation of the distance between encounters, a necessary component of path-integration that enables computing allocentric spatial relations. Our results suggest that similar mechanisms are involved in sequential spatial learning in all vertebrates.

Nonstationary Stochastic Dynamics Underlie Spontaneous Transitions between Active and Inactive Behavioral States.

The neural basis of spontaneous movement generation is a fascinating open question. Long-term monitoring of fish, swimming freely in a constant sensory environment, has revealed a sequence of behavioral states that alternate randomly and spontaneously between periods of activity and inactivity. We show that key dynamical features of this sequence are captured by a 1-D diffusion process evolving in a nonlinear double well energy landscape, in which a slow variable modulates the relative depth of the wells. This combination of stochasticity, nonlinearity, and nonstationary forcing correctly captures the vastly different timescales of fluctuations observed in the data (∼1 to ∼1000 s), and yields long-tailed residence time distributions (RTDs) also consistent with the data. In fact, our model provides a simple mechanism for the emergence of long-tailed distributions in spontaneous animal behavior. We interpret the stochastic variable of this dynamical model as a decision-like variable that, upon reaching a threshold, triggers the transition between states. Our main finding is thus the identification of a threshold crossing process as the mechanism governing spontaneous movement initiation and termination, and to infer the presence of underlying nonstationary agents. Another important outcome of our work is a dimensionality reduction scheme that allows similar segments of data to be grouped together. This is done by first extracting geometrical features in the dataset and then applying principal component analysis over the feature space. Our study is novel in its ability to model nonstationary behavioral data over a wide range of timescales.

Clusters of midlife women by physical activity and their racial/ethnic differences.

OBJECTIVE: The purpose of this study was to identify clusters of midlife women by physical activity and to determine racial/ethnic differences in physical activities in each cluster. METHODS: This was a secondary analysis of the data from 542 women (157 non-Hispanic [NH] Whites, 127 Hispanics, 135 NH African Americans, and 123 NH Asian) in a larger Internet study on midlife women's attitudes toward physical activity. The instruments included the Barriers to Health Activities Scale, the Physical Activity Assessment Inventory, the Questions on Attitudes toward Physical Activity, Subjective Norm, Perceived Behavioral Control, and Behavioral Intention, and the Kaiser Physical Activity Survey. The data were analyzed using hierarchical cluster analyses, analysis of variance, and multinominal logistic analyses. RESULTS: A three-cluster solution was adopted: cluster 1 (high active living and sports/exercise activity group; 48%), cluster 2 (high household/caregiving and occupational activity group; 27%), and cluster 3 (low active living and sports/exercise activity group; 26%). There were significant racial/ethnic differences in occupational activities of clusters 1 and 3 (all P < 0.01). Compared with cluster 1, cluster 2 tended to have lower family income, less access to health care, higher unemployment, higher perceived barriers scores, and lower social influences scores (all P < 0.01). Compared with cluster 1, cluster 3 tended to have greater obesity, less access to health care, higher perceived barriers scores, more negative attitudes toward physical activity, and lower self-efficacy scores (all P < 0.01). CONCLUSIONS: Midlife women's unique patterns of physical activity and their associated factors need to be considered in future intervention development.