5-hydroxytryptamine 3 (5HT3) receptors are important modulators of mesostriatal dopaminergic transmission and have been implicated in the pathophysiology of cocaine reward, withdrawal, and self-administration. In addition, the 5HT3 antagonist ondansetron is effective in treating early-onset, but not late-onset, alcohol-dependent subjects. To explore the role of 5HT3 receptor systems in cocaine addiction using functioning imaging, we administered ondansetron to 23 abstinent, treatment-seeking cocaine-addicted and 22 sex-, age-, and race-matched healthy control participants. Differences between early- (first use before 20 years, n=10) and late-onset (first use after 20 years, n=10) cocaine-addicted subjects were also assessed. On two separate days, subjects were administered ondansetron (0.15 mg/kg intravenously over 15 min) or saline. Regional cerebral blood flow (rCBF) was measured following each infusion with single photon emission computed tomography (SPECT). No significant rCBF differences between the cocaine-addicted and control participants were observed following ondansetron relative to saline. Early-onset subjects, however, showed increased (p < 0.001) right posterior parahippocampal rCBF following ondansetron. In contrast, late-onset subjects showed decreased rCBF following ondansetron in an overlapping region of the right parahippocampal/hippocampal gyrus. Early-onset subjects also displayed increased rCBF in the left anterior insula and subthalamic nucleus following ondansetron; late-onset subjects showed decreased rCBF in the right anterior insula. These findings suggest that age of drug use onset is associated with serotonergic biosignatures in cocaine-addicted subjects. Further clarification of these alterations may guide targeted treatment with serotonergic medications similar to those successfully used in alcohol-dependent patients.
We described influences on past research participation among low-income persons living with HIV (PLWH) and examined whether such influences differed by study type. We analyzed a convenience sample of individuals from a large, urban clinic specializing in treating low-income PLWH. Using a computer-assisted survey, we elicited perceptions of research and participating in research, barriers, benefits, “trigger” influences, and self-efficacy in participating in research. Of 193 participants, we excluded 14 who did not identify any type of study participation, and 17 who identified “other” as study type, resulting in 162 cases for analysis. We compared results among four groups (i.e., 6 comparisons): past medical participants (n=36, 22%), past behavioral participants (n=49, 30%), individuals with no past research participation (n=52, 32%), and persons who had participated in both medical and behavioral studies (n=25, 15%). Data were analyzed using chi-square tests for categorical variables and ANOVA for continuous variables. We employed a multinomial probit (MNP) model to examine the association of multiple factors with the outcome. Confidence in ability to keep appointments, and worry about being a ‘guinea pig’ showed statistical differences in bivariate analyses. The MNP regression analysis showed differences between and across all 6 comparison groups. Fewer differences were seen across groupings of medical participants, behavioral participants, and those with no past research experience, than in comparisons with the medical-behavioral group. In the MNP regression model ‘age’ and level of certainty regarding ‘keeping yourself from being a guinea pig’ showed significant differences between past medical participants and past behavioral participants.
Old age is associated with reduced mobility of the hand. To investigate age related decline when reaching-to-lift an object we used sophisticated kinematic apparatus to record reaches carried out by healthy older and younger participants. Three objects of different widths were placed at three different distances, with objects having either a high or low friction surface (i.e. rough or slippery). Older participants showed quantitative differences to their younger counterparts – movements were slower and peak speed did not scale with object distance. There were also qualitative differences with older adults showing a greater propensity to stop the hand and adjust finger position before lifting objects. The older participants particularly struggled to lift wide slippery objects, apparently due to an inability to manipulate their grasp to provide the level of precision necessary to functionally enclose the object. These data shed light on the nature of age related changes in reaching-to-grasp movements and establish a powerful technique for exploring how different product designs will impact on prehensile behavior.
Replication by Escherichia coli DNA polymerase III is disrupted on encountering DNA damage. Consequently, specialized Y-family DNA polymerases are used to bypass DNA damage. The protein UmuD is extensively involved in modulating cellular responses to DNA damage and may play a role in DNA polymerase exchange for damage tolerance. In the absence of DNA, UmuD interacts with the α subunit of DNA polymerase III at two distinct binding sites, one of which is adjacent to the single-stranded DNA-binding site of α. Here, we use single molecule DNA stretching experiments to demonstrate that UmuD specifically inhibits binding of α to ssDNA. We predict using molecular modeling that UmuD residues D91 and G92 are involved in this interaction and demonstrate that mutation of these residues disrupts the interaction. Our results suggest that competition between UmuD and ssDNA for α binding is a new mechanism for polymerase exchange.
Developmental Coordination Disorder (DCD) affects a relatively large proportion
(5–6%) of the childhood population. Severity of the disorder varies but there is a
great need for therapeutic intervention. We propose a method for the training of manual actions in
children with DCD. Our solution is achieved by applying haptic virtual reality technology to attack
the difficulties that children with DCD evidence. Our results show that children with DCD are able
to learn complex motor skills if proper training methods are employed. These findings conflict with
reports of impaired motor learning in DCD because of under-activation of cerebellar and parietal
Developmental coordination disorder; sensori-motor training; manual actions
Unresolved medication discrepancies during hospitalization can contribute to adverse drug events, resulting in patient harm. Discrepancies can be reduced by performing medication reconciliation; however, effective implementation of medication reconciliation has proven to be challenging. The goals of the Multi-Center Medication Reconciliation Quality Improvement Study (MARQUIS) are to operationalize best practices for inpatient medication reconciliation, test their effect on potentially harmful unintentional medication discrepancies, and understand barriers and facilitators of successful implementation.
Six U.S. hospitals are participating in this quality improvement mentored implementation study. Each hospital has collected baseline data on the primary outcome: the number of potentially harmful unintentional medication discrepancies per patient, as determined by a trained on-site pharmacist taking a “gold standard” medication history. With the guidance of their mentors, each site has also begun to implement one or more of 11 best practices to improve medication reconciliation. To understand the effect of the implemented interventions on hospital staff and culture, we are performing mixed methods program evaluation including surveys, interviews, and focus groups of front line staff and hospital leaders.
At baseline the number of unintentional medication discrepancies in admission and discharge orders per patient varies by site from 2.35 to 4.67 (mean=3.35). Most discrepancies are due to history errors (mean 2.12 per patient) as opposed to reconciliation errors (mean 1.23 per patient). Potentially harmful medication discrepancies averages 0.45 per patient and varies by site from 0.13 to 0.82 per patient. We discuss several barriers to implementation encountered thus far. In the end, we anticipate that MARQUIS tools and lessons learned have the potential to decrease medication discrepancies and improve patient outcomes.
Clinicaltrials.gov identifier NCT01337063
Medication reconciliation; Hospitalization; Quality improvement; Care transitions
The tumor necrosis factor (TNF) superfamily member TNF-like weak inducer of apoptosis (TWEAK) is a pro-inflammatory and pro-angiogenic cytokine implicated in physiological tissue regeneration and wound repair. TWEAK binds to a 102-amino acid type I transmembrane cell surface receptor named fibroblast growth factor-inducible 14 (Fn14). TWEAK:Fn14 engagement activates several intracellular signaling cascades, including the NF-κB pathway, and sustained Fn14 signaling has been implicated in the pathogenesis of chronic inflammatory diseases and cancer. Although several groups are developing TWEAK- or Fn14-targeted agents for therapeutic use, much more basic science research is required before we fully understand the TWEAK/Fn14 signaling axis. For example, we and others have proposed that TWEAK-independent Fn14 signaling may occur in cells when Fn14 levels are highly elevated, but this idea has never been tested directly. In this report, we first demonstrate TWEAK-independent Fn14 signaling by showing that an Fn14 deletion mutant that is unable to bind TWEAK can activate the NF-κB pathway in transfected cells. We then show that ectopically-expressed, cell surface-localized Fn14 can self-associate into Fn14 dimers, and we show that Fn14 self-association is mediated by an 18-aa region within the Fn14 cytoplasmic domain. Endogenously-expressed Fn14 as well as ectopically-overexpressed Fn14 could also be detected in dimeric form when cell lysates were subjected to SDS-PAGE under non-reducing conditions. Additional experiments revealed that Fn14 dimerization occurs during cell lysis via formation of an intermolecular disulfide bond at cysteine residue 122. These findings provide insight into the Fn14 signaling mechanism and may aid current studies to develop therapeutic agents targeting this small cell surface receptor.
Depression poses a significant economic and health burden, yet it remains underdiagnosed and inadequately treated. The STAR*D trial funded by the National Institute of Mental Health showed that more than one antidepressant medication is often necessary to achieve disease remission among patients seen in both psychiatric and primary care settings. The collaborative care model (CCM), using care managers, has been shown to be effective in numerous studies in achieving sustained outcomes in depression management compared to usual care. This model was adopted in a statewide depression treatment improvement initiative among primary care clinics in Minnesota, which was launched in March 2008. In this study, records of patients who were enrolled in CCM from March 2008 until March 2009 were reviewed and compared to those under usual care. Patients who were followed under the CCM had a significantly greater number of antidepressant medication utilizations when compared to those under usual care. After 6 months, mean PHQ-9 score of patients under CCM was statistically lower than those in usual care. There was no significant difference in both mean PHQ-9 scores at 6 months and antidepressant utilization between the 2 groups among patients aged 65 years and older.
Collaborative care; depression; medications; management; utilization.
Comparative effectiveness research (CER) documents important differences in antidepressants in terms of efficacy, safety, cost, and burden to the patient. Decision aids can adapt this evidence to help patients participate in making informed choices. In turn, antidepressant therapy will more likely reflect patients’ values and context, leading to improved adherence and mood outcomes.
The objective of this study is to develop the Depression Medication Choice decision aid for use during primary care encounters, and to test its efficacy by conducting a clustered practical randomized trial comparing the decision aid to usual depression care in primary care practices.
We will use a novel practice-based, patient-centered approach based on participatory action research that involves a multidisciplinary team of designers, investigators, clinicians, patient representatives, and other stakeholders for the development of the decision aid. We will then conduct a clustered practical randomized trial enrolling clinicians and their patients (n = 300) with moderate to severe depression from rural, suburban and inner city primary care practices (n = 10). The intervention will consist of the use of the depression medication choice decision aid during the clinical encounter. This trial will generate preliminary evidence of the relative impact of the decision aid on patient involvement in decision making, decision making quality, patient knowledge, and 6-month measures of medication adherence and mental health compared to usual depression care.
Upon completion of the proposed research, we will have developed and evaluated the efficacy of the decision aid depression medication choice as a novel translational tool for CER in depression treatment, engaged patients with depression in their care, and refined the process by which we conduct practice-based trials with limited research footprint.
Clinical Trials.gov: NCT01502891
Depression; Comparative effectiveness research; Shared decision making; Decision aid; Implementation; Randomized controlled trial
The purpose of the study was to document development costs and estimate implementation costs of an internet based medication adherence intervention for people living with HIV in the US. Participants (n=61) were enrolled in the 8 week study in 2011 and entered the intervention website remotely in the setting of their choice. Development costs were obtained from a feasibility and acceptability study of an internet based medication adherence intervention. Implementation costs were estimated based on an 8 week trial period during the feasibility and acceptability study. Results indicated that although developing an internet based medication adherence intervention is expensive, the monthly cost of implementing and delivering the intervention is low. If the efficacy of similar interventions can be established, these results suggest the internet could be an effective method for delivering medication adherence interventions to persons residing in areas with limited access to in-person adherence services.
The objective of this study was to evaluate the reproducibility of the cervical range of motion device when measuring both active and passive range of motion in a group of individuals with sub-acute Whiplash Associated Disorders (WAD).
Participants were recruited as part of a large multi-centre Randomised Controlled Trial from UK emergency departments. Experienced research physiotherapists measured active and passive cervical spine movements in all directions. Both intra- and inter-observer reliability and agreement were assessed using the intra-class correlation coefficient, standard error of measurement and limits of agreement methods.
Different groups of 39 and 19 subjects were included in the intra and inter-observer studies, respectively. The CROM device demonstrated substantial intra- and inter-observer reliability and agreement for all the active and passive half-cycle movements (ICC range 0.82–0.99) with the exception of one (passive right lateral flexion for inter-observer; ICC 0.77).
The CROM device has proven to be a reproducible measurement method for a symptomatic WAD population using the measurement protocol described and can be used with confidence to differentiate individuals according to a single measurement.
MeSH term ‘Reproducibility of results’; Cervical spine; CROM
It is unknown if online social networking technologies are already highly integrated among some people living with HIV (PLWH) or have yet to be adopted. To fill this gap in understanding, 312 PLWH (84% male, 69% white) residing in the US completed on online survey in 2009 of their patterns of social networking and mobile phone use. Twenty-two persons also participated in one of two online focus groups. Results showed that 76% of participants with lower adherence to HIV medication used social networking websites/features at least once a week. Their ideal online social networking health websites included one that facilitated socializing with others (45% of participants) and relevant informational content (22%), although privacy was a barrier to use (26%). Texting (81%), and to a lesser extent mobile web-access (51%), was widely used among participants. Results support the potential reach of online social networking and text messaging intervention approaches.
Online social network; mobile phone; online survey; online focus group; people living with HIV
Previous studies have indicated that saccadic eye movements correlate positively with perceptual alternations in binocular rivalry, presumably because the foveal image changes resulting from saccades, rather than the eye movement themselves, cause switches in awareness. Recently, however, we found evidence that retinal image shifts elicit so-called onset rivalry and not percept switches as such. These findings raise the interesting question whether onset rivalry may account for correlations between saccades and percept switches.
We therefore studied binocular rivalry when subjects made eye movements across a visual stimulus and compared it with the rivalry in a ‘replay’ condition in which subjects maintained fixation while the same retinal displacements were reproduced by stimulus displacements on the screen. We used dichoptic random-dot motion stimuli viewed through a stereoscope, and measured eye and eyelid movements with scleral search-coils.
Positive correlations between retinal image shifts and perceptual switches were observed for both saccades and stimulus jumps, but only for switches towards the subjects' preferred eye at stimulus onset. A similar asymmetry was observed for blink-induced stimulus interruptions. Moreover, for saccades, amplitude appeared crucial as the positive correlation persisted for small stimulus jumps, but not for small saccades (amplitudes < 1°). These findings corroborate our tenet that saccades elicit a form of onset rivalry, and that rivalry is modulated by extra-retinal eye movement signals.
To define the relationship between hospital patient safety climate (a measure of hospitals' organizational culture as related to patient safety) and hospitals' rates of rehospitalization within 30 days of discharge.
A safety climate survey administered to a random sample of hospital employees (n=36,375) in 2006–2007 and risk-standardized hospital readmission rates from 2008.
Cross-sectional study of 67 hospitals.
Robust multiple regressions used 30-day risk-standardized readmission rates as dependent variables in separate disease-specific models (acute myocardial infarction [AMI], heart failure [HF], pneumonia), and measures of safety climate as independent variables. We estimated separate models for all hospital staff as well as physicians, nurses, hospital senior managers, and frontline staff.
There was a significant positive association between lower safety climate and higher readmission rates for AMI and HF (p≤.05 for both models). Frontline staff perceptions of safety climate were associated with readmission rates (p≤.01), but senior management perceptions were not. Physician and nurse perceptions related to AMI and HF readmissions, respectively.
Our findings indicate that hospital patient safety climate is associated with readmission outcomes for AMI and HF and those associations were management level and discipline specific.
Safety culture; safety climate; hospital readmission
Central Sensitization (CS) has been proposed as a common pathophysiological mechanism to explain related syndromes for which no specific organic cause can be found. The term Central Sensitivity Syndrome (CSS) has been proposed to describe these poorly understood disorders related to CS. The goal of this investigation was to develop the Central Sensitization Inventory (CSI), which identifies key symptoms associated with CSSs, and quantifies the degree of these symptoms. The utility of the CSI, to differentiate among different types of chronic pain patients that presumably have different levels of CS impairment, was then evaluated. Study 1 demonstrated strong psychometric properties (test-retest reliability = 0.817; Cronbach's alpha = 0.879) of the CSI in a cohort of normative subjects. A factor analysis (including both normative and chronic pain subjects) yielded 4 major factors (all related to somatic and emotional symptoms), accounting for 53.4% of the variance in the dataset. In Study 2, the CSI was administered to four groups: fibromyalgia (FM); chronic widespread pain (CWP) without FM; work-related regional chronic low back pain (CLBP); and normative control group. Analyses revealed that the FM patients reported the highest CSI scores, and the normative population the lowest (p<.05). Analyses also demonstrated that the prevalence of previously diagnosed CSSs and related disorders was highest in the FM group and lowest in the normative group (p<.001). Taken together, these two studies demonstrate the psychometric strength, clinical utility, and the initial construct validity of the CSI in evaluating CS-related clinical symptoms in chronic pain populations.
Central Sensitization Inventory (CSI); Central Sensitization; Central Sensitivity Syndrome; chronic pain; factor analysis; reliability; Fibromyalgia; work-related lumbar pain
It has been suggested that the antidepressant effect of laser acupuncture involves modulation of the default mode network (DMN) or resting state network (RSN). In this study, the authors investigated changes in the DMN during laser acupuncture in depressed and nondepressed participants.
To aim of this study was to determine if the modulation of the DMN effects by laser acupuncture in depressed participants are different from those of nondepressed participants.
Randomized stimulation was performed with laser acupuncture on four putative antidepressant acupoints (LR 14, LR 8, CV 14, and HT 7) in a block on–off design, while the blood oxygenation level–dependent (BOLD) fMRI response was recorded from each subject's whole brain on a 3T scanner. DMN patterns of the participants were identified, using an independent component analysis. The identified DMN components from both the nondepressed group and the depressed group were then analytically compared using SPM5.
This study took place at a research institute.
Ten nondepressed participants and 10 depressed participants (DS) as confirmed by the Hamilton Depression Rating Scale (HAM-D) participated in this study.
Low Intensity Laser Acupuncture.
Main outcome measures
Significant DMN patterns in one group were greater than those in the other group.
The nondepressed participants had significant modulation of DMN in the frontal region at the medial frontal gyrus (verum laser>rest, p<0.001) for three acupoints (LR 14, LR 8, and CV 14). For the depressive participants, the DMN modulation occurred at the inferior parietal cortex and the cerebellum (verum laser>rest, p<0.001).
Laser acupuncture on LR 8, LR 14, and CV 14 stimulated both the anterior and posterior DMN in both the nondepressed and depressed participants. However, in the nondepressed participants, there was consistently outstanding modulation of the anterior DMN at the medial frontal gyrus across all three acupoints. In the depressed participants, there was wider posterior DMN modulation at the parieto–temporal–limbic cortices. This is part of the antidepressant effect of laser acupuncture.
Low Intensity Laser; Acupuncture; Acupoints; Default Mode Network
Relapse may occur suddenly, following a short period of craving, or after extended consideration. The time to relapse may reveal underlying mechanisms of relapse and have important implications for treatment.
The Time to Relapse Questionnaire (TRQ), a self-administered questionnaire, was designed to assess the time from the initial thought of drug use to actual use.
Psychometric properties of the TRQ were evaluated in two distinct populations (n = 183 and 194) with DSM-IV primary substance use disorders.
Factor analysis and item refine-ment led to a 9-item TRQ with a three-factor solution accounting for 63% of the total variance. Three discrete types of relapse style were identified: Sudden Relapse, Short Delay Relapse, and Long Delay Relapse. The TRQ demonstrated good construct validity and adequate internal consistency for the total (α= .61) and individual factor (α= .64–.75) scores. Measures to assess convergent validity of the TRQ suggest that Sudden Relapse may not reflect more generalized deficits of inhibitory control.
Conclusions and Significance
The TRQ may provide a useful self-report measure to discriminate between addicted patients who relapse without forewarning compared to those with a period of delay. Clinical interventions may be targeted towards different relapse styles.
impulsive behaviour; questionnaires; recurrence; substance-related disorders
Previous observational studies using differing methodologies have yielded inconsistent results regarding the association between glycemic control and outcomes in diabetic patients receiving maintenance hemodialysis (MHD). We examined mortality predictability of A1C and random serum glucose over time in a contemporary cohort of 54,757 diabetic MHD patients (age 63 ± 13 years, 51% men, 30% African Americans, 19% Hispanics). Adjusted all-cause death hazard ratio (HR) for baseline A1C increments of 8.0–8.9, 9.0–9.9, and ≥10%, compared with 7.0–7.9% (reference), was 1.06 (95% CI 1.01–1.12), 1.05 (0.99–1.12), and 1.19 (1.12–1.28), respectively, and for time-averaged A1C was 1.11 (1.05–1.16), 1.36 (1.27–1.45), and 1.59 (1.46–1.72). A symmetric increase in mortality also occurred with time-averaged A1C levels in the low range (6.0–6.9%, HR 1.05 [95% CI 1.01–1.08]; 5.0–5.9%, 1.08 [1.04–1.11], and ≤5%, 1.35 [1.29–1.42]) compared with 7.0–7.9% in fully adjusted models. Adjusted all-cause death HR for time-averaged blood glucose 175–199, 200–249, 250–299, and ≥300 mg/dL, compared with 150–175 mg/dL (reference), was 1.03 (95% CI 0.99–1.07), 1.14 (1.10–1.19), 1.30 (1.23–1.37), and 1.66 (1.56–1.76), respectively. Hence, poor glycemic control (A1C ≥8% or serum glucose ≥200 mg/dL) appears to be associated with high all-cause and cardiovascular death in MHD patients. Very low glycemic levels are also associated with high mortality risk.
Clinically important medication errors are common after hospital discharge. They include preventable or ameliorable adverse drug events as well as medication discrepancies or non-adherence with high potential for future harm (potential adverse drug events).
The Pharmacist Intervention for Low Literacy in Cardiovascular Disease (PILL-CVD) study sought to determine the effect of a tailored intervention on the occurrence of clinically important medication errors after hospital discharge.
Randomized controlled trial with concealed allocation and blinded outcome assessors.
Two tertiary care academic hospitals.
Adults hospitalized with acute coronary syndromes or acute decompensated heart failure.
Pharmacist-assisted medication reconciliation, inpatient pharmacist counseling, low-literacy adherence aids, and individualized telephone follow-up after discharge.
The primary outcome was the number of clinically important medication errors per patient during the first 30 days after hospital discharge. Secondary outcomes included preventable or ameliorable adverse drug events, as well as potential adverse drug events.
Among 851 participants, 432 (50.8%) experienced 1 or more clinically important medication errors; 23% of such errors were judged to be serious, and 2% life-threatening. Adverse drug events occurred in 258 patients (30.3%) and potential adverse drug events in 253 (29.7%). The intervention did not significantly alter the per-patient number of clinically important medication errors (IRR=0.92; 95% CI, 0.77 to 1.10) or adverse drug events (IRR=1.09; CI, 0.86 to 1.39). Intervention patients tended to have fewer potential adverse drug events (IRR=0.80; CI, 0.61 to 1.04).
The characteristics of the study hospitals and participants may limit generalizability.
Clinically important medication errors were present among half of patients after hospital discharge and were not significantly reduced by a health-literacy sensitive, pharmacist-delivered intervention.
care transitions; health literacy; medication safety
HMGB proteins are members of a class of small proteins that are ubiquitous in eukaryotic cells and non-specifically bind to DNA, inducing large-angle DNA bends, enhancing the flexibility of DNA, and likely facilitating numerous important biological interactions. To determine the nature of this behavior for different HMGB proteins, we used atomic force microscopy (AFM) to quantitatively characterize the bend angle distributions of DNA complexes with human HMGB2(Box A), yeast Nhp6A, and two chimeric mutants of these proteins. While all of the HMGB proteins bend DNA to preferred angles, Nhp6A promoted the formation of higher-order oligomer structures and induced a significantly broader distribution of angles, suggesting that the mechanism of Nhp6A is more like a flexible hinge than that of HMGB2(Box A). To determine the structural origins of this behavior, we used portions of the cationic N-terminus of Nhp6A to replace corresponding HMGB2(Box A) sequences. We found that the oligomerization and broader angle distribution correlated directly with the length of the N-terminus incorporated into the HMGB2(Box A) construct. Therefore, the basic N-terminus of Nhp6A is responsible for its ability to act as a flexible hinge and form high order structures.
single molecule; DNA binding; DNA melting; HMGB2; atomic force microscopy
The present study investigated whether emotional conflict and emotional conflict adaptation could be triggered by unconscious emotional information as assessed in a backward-masked affective priming task. Participants were instructed to identify the valence of a face (e.g., happy or sad) preceded by a masked happy or sad face. The results of two experiments revealed the emotional conflict effect but no emotional conflict adaptation effect. This demonstrates that emotional conflict can be triggered by unconsciously presented emotional information, but participants may not adjust their subsequent performance trial-by trial to reduce this conflict.
Hemianopia patients have lost vision from the contralateral hemifield, but make behavioural adjustments to compensate for this field loss. As a result, their visual performance and behaviour contrast with those of hemineglect patients who fail to attend to objects contralateral to their lesion. These conditions differ in their ocular fixations and perceptual judgments. During visual search, hemianopic patients make more fixations in contralesional space while hemineglect patients make fewer. During line bisection, hemianopic patients fixate the contralesional line segment more and make a small contralesional bisection error, while hemineglect patients make few contralesional fixations and a larger ipsilesional bisection error. Hence, there is an attentional failure for contralesional space in hemineglect but a compensatory adaptation to attend more to the blind side in hemianopia. A challenge for models of visual attentional processes is to show how compensation is achieved in hemianopia, and why such processes are hindered or inaccessible in hemineglect. We used a neurophysiology-derived computational model to examine possible cortical compensatory processes in simulated hemianopia from a V1 lesion and compared results with those obtained with the same processes under conditions of simulated hemineglect from a parietal lesion. A spatial compensatory bias to increase attention contralesionally replicated hemianopic scanning patterns during visual search but not during line bisection. To reproduce the latter required a second process, an extrastriate lateral connectivity facilitating form completion into the blind field: this allowed accurate placement of fixations on contralesional stimuli and reproduced fixation patterns and the contralesional bisection error of hemianopia. Neither of these two cortical compensatory processes was effective in ameliorating the ipsilesional bias in the hemineglect model. Our results replicate normal and pathological patterns of visual scanning, line bisection, and differences between hemianopia and hemineglect, and may explain why compensatory processes that counter the effects of hemianopia are ineffective in hemineglect.
Brain regions in the intraparietal and the premotor cortices selectively process visual and multisensory events near the hands (peri-hand space). Visual information from the hand itself modulates this processing potentially because it is used to estimate the location of one’s own body and the surrounding space. In humans specific occipitotemporal areas process visual information of specific body parts such as hands. Here we used an fMRI block-design to investigate if anterior intraparietal and ventral premotor ‘peri-hand areas’ exhibit selective responses to viewing images of hands and viewing specific hand orientations. Furthermore, we investigated if the occipitotemporal ‘hand area’ is sensitive to viewed hand orientation. Our findings demonstrate increased BOLD responses in the left anterior intraparietal area when participants viewed hands and feet as compared to faces and objects. Anterior intraparietal and also occipitotemporal areas in the left hemisphere exhibited response preferences for viewing right hands with orientations commonly viewed for one’s own hand as compared to uncommon own hand orientations. Our results indicate that both anterior intraparietal and occipitotemporal areas encode visual limb-specific shape and orientation information.
Research exploring the role of spatial frequencies in rapid stimulus detection and categorization report flexible reliance on specific spatial frequency (SF) bands. Here, through a set of behavioral and magnetoencephalography (MEG) experiments, we investigated the role of low spatial frequency (LSF) (<8 cycles/face) and high spatial frequency (HSF) (>25 cycles/face) information during the categorization of faces and places. Reaction time measures revealed significantly faster categorization of faces driven by LSF information, while rapid categorization of places was facilitated by HSF information. The MEG study showed significantly earlier latency of the M170 component for LSF faces compared to HSF faces. Moreover, the M170 amplitude was larger for LSF faces than for LSF places, whereas the reverse pattern was evident for HSF faces and places. These results suggest that SF modulates the processing of category specific information for faces and places.
spatial frequency; face perception; place perception; M170