Faculty Bibliography

Traditionally, crawling and sitting are considered distinct motor behaviors with different postures and functions. Ten- to 12-month-old infants were observed in the laboratory or in their homes while being coaxed to crawl continuously over long, straight walkways (Study 1; N = 20) and during spontaneous crawling during free play (Study 2; N = 20). In every context, infants stopped crawling to sit 3-6 times per minute. Transitions from crawling to sitting frequently turned infants' bodies away from the direction of heading; subsequent transitions back to crawling were offset by as much as 180 degrees from the original direction of heading. Apparently, body reorientations result from the biomechanics of transitioning between crawling and sitting. Findings indicate that sustained, linear crawling is likely an epiphenomenon of how gait is studied in standard paradigms. Postural transitions between crawling and sitting are ubiquitous and can represent a functional unit of action. These transitions and the accompanying body reorientations likely have cascading effects for infants' exploration, visual perception, and spatial cognition.

Visual exploration in infants and adults has been studied using two very different paradigms: free viewing of flat screen displays in desk-mounted eye-tracking studies and real-world visual guidance of action in head-mounted eye-tracking studies. To test whether classic findings from screen-based studies generalize to real-world visual exploration and to compare natural visual exploration in infants and adults, we tested observers in a new paradigm that combines critical aspects of both previous techniques: free viewing during real-world visual exploration. Mothers and their 9-month-old infants wore head-mounted eye trackers while mothers carried their infants in a forward-facing infant carrier through a series of indoor hallways. Demands for visual guidance of action were minimal in mothers and absent for infants, so both engaged in free viewing while moving through the environment. Similar to screen-based studies, during free viewing in the real world low-level saliency was related to gaze direction. In contrast to screen-based studies, only infants - not adults - were biased to look at people, participants of both ages did not show a classic center bias, and mothers and infants did not display high levels of inter-observer consistency. Results indicate that several aspects of visual exploration of a flat screen display do not generalize to visual exploration in the real world.

Global visual processing is important for segmenting scenes, extracting form from background, and recognizing objects. Local processing involves attention to the local elements, contrast, and boundaries of an image at the expense of extracting a global percept. Previous work is inconclusive regarding the relative development of local and global processing. Some studies suggest that global perception is already present by 8 months of age, whereas others suggest that the ability arises during childhood and continues to develop during adolescence. We used a novel method to assess the development of global processing in 3- to 10-year-old children and an adult comparison group. We used Kanizsa illusory contours as an assay of global perception and measured responses on a touch-sensitive screen while monitoring eye position with a head-mounted eye tracker. Participants were tested using a similarity match-to-sample paradigm. Using converging measures, we found a clear developmental progression with age such that the youngest children performed near chance on the illusory contour discrimination, whereas 7- and 8-year-olds performed nearly perfectly, as did adults. There was clear evidence of a gradual shift from a local processing strategy to a global one; young children looked predominantly at and touched the "pacman" inducers of the illusory form, whereas older children and adults looked predominantly at and touched the middle of the form. These data show a prolonged developmental trajectory in appreciation of global form, with a transition from local to global visual processing between 4 and 7 years of age.

Homotopy reflects the intrinsic functional architecture of the brain through synchronized spontaneous activity between corresponding bilateral regions, measured as voxel mirrored homotopic connectivity (VMHC). Hypercapnia is known to have clear impact on brain hemodynamics through vasodilation, but have unclear effect on neuronal activity. This study investigates the effect of hypercapnia on brain homotopy, achieved by breathing 5% carbon dioxide (CO2 ) gas mixture. A total of 14 healthy volunteers completed three resting state functional MRI (RS-fMRI) scans, the first and third under normocapnia and the second under hypercapnia. VMHC measures were calculated as the correlation between the BOLD signal of each voxel and its counterpart in the opposite hemisphere. Group analysis was performed between the hypercapnic and normocapnic VMHC maps. VMHC showed a diffused decrease in response to hypercapnia. Significant regional decreases in VMHC were observed in all anatomical lobes, except for the occipital lobe, in the following functional hierarchical subdivisions: the primary sensory-motor, unimodal, heteromodal, paralimbic, as well as in the following functional networks: ventral attention, somatomotor, default frontoparietal, and dorsal attention. Our observation that brain homotopy in RS-fMRI is affected by arterial CO2 levels suggests that caution should be used when comparing RS-fMRI data between healthy controls and patients with pulmonary diseases and unusual respiratory patterns such as sleep apnea or chronic obstructive pulmonary disease. Hum Brain Mapp, 2015. (c) 2015 Wiley Periodicals, Inc.

BACKGROUND: Prior follow-up studies of attention-deficit/hyperactivity disorder (ADHD) ascertained ADHD cases in clinical samples mostly from North America but rarely from European countries. They have provided a good deal of information about the persistence of ADHD and its impairments, but the degree to which these results generalize to population samples and to other countries is not certain. Prior studies have also not assessed predictors of new-onset ADHD in youth without ADHD. METHOD: At baseline, 7,912 of 18 million telephone numbers were randomly selected from throughout France from October 2, 2008, through December 11, 2008. Among 4,186 eligible families, 1,012 (24.2%) were successfully recruited at baseline, when a telephone interview was administered to all families about a child in the 6- to 12-year age range. Four years later, we attempted to recruit the entire sample to assess the persistence of ADHD and its impairments and the emergence of new associated conditions. RESULTS: 86.5% of the families assessed at baseline were followed-up (N = 875). Participants who were and were not interviewed at follow-up did not differ on any clinical or demographic features. At follow-up, the prevalence of full or subthreshold ADHD was 65.8% for ADHD participants and 9.8% for those not having ADHD at baseline. Among the children who were not diagnosed with ADHD at baseline, 3.4% were diagnosed with ADHD at follow-up. Both the persistence of ADHD and new onsets of ADHD were significantly predicted by several baseline clinical features and by having a family history of ADHD (all P values < .05). CONCLUSIONS: We replicated prior predictors of ADHD's persistence and provide new data about predictors of new ADHD onsets in the population. Our data about subthreshold ADHD support a dimensional conceptualization of the disorder and address the potential clinical utility of a subthreshold diagnostic category.

STUDY OBJECTIVES: To evaluate the frequency, severity, and associations of symptoms of attention-deficit/hyperactivity disorder (ADHD) in children with narcolepsy with and without cataplexy. DESIGN: Cross-sectional survey. SETTING: Four French national reference centers for narcolepsy. PATIENTS: One hundred eight consecutively referred children aged younger than 18 y with narcolepsy, with (NwC, n = 86) or without cataplexy (NwoC, n = 22), and 67 healthy controls. INTERVENTIONS: The participants, their families, and sleep specialists completed a structured interview and questionnaires about sleep, daytime sleepiness, fatigue, and ADHD symptoms (ADHD-rating scale based upon Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision [DSM-IV-TR] symptoms), and use of psychostimulants for the treatment of narcolepsy (administered in 68.2%). Polysomnographic measures were collected. MEASUREMENTS AND RESULTS: Clinically significant levels of ADHD symptoms were found in 4.8% of controls compared with 35.3% in patients with NwoC (P < 0.001) and 19.7% in patients with NwC (P < 0.01). Total ADHD scores were 6.4 (95% confidence interval [CI]: 4.5, 9.0) in controls compared with 14.2 (95% CI: 10.6, 18.9; P < 0.001), in patients with NwoC and 12.2 (95% CI: 9.8, 15.3; P < 0.01) in patients with NwC; subscores of inattention and hyperactivity/impulsivity were also significantly higher in both narcolepsy groups compared with controls. No difference was found between the NwC and NwoC groups for any ADHD measure. ADHD symptom severity was associated with increased levels of sleepiness, fatigue, and insomnia. Compared with the 34 untreated patients, the 73 patients treated with psychostimulants (modafinil in 91%) showed a trend toward lower narcolepsy symptoms but not lower ADHD symptoms. CONCLUSIONS: Pediatric patients with narcolepsy have high levels of treatment-resistant ADHD symptoms. The optimal treatment for ADHD symptoms in these patients warrants further evaluation in longitudinal intervention studies.

The "ten ironic rules for statistical reviewers" presented by Friston (2012) prompted a rebuttal by Lindquist et al. (2013), which was followed by a rejoinder by Friston (2013). A key issue left unresolved in this discussion is the use of cross-validation to test the significance of predictive analyses. This note discusses the role that cross-validation-based and related hypothesis tests have come to play in modern data analyses, in neuroimaging and other fields. It is shown that such tests need not be suboptimal and can fill otherwise-unmet inferential needs.

BACKGROUND: Social dysfunction is common among individuals with schizophrenia. While often attributed to anhedonia, social dysfunction could also result from unrecognized anxiety. We examined the contributions of anhedonia and anxiety to social function using olfactory function to examine whether the domains had separate underpinnings. METHODS: We assessed anhedonia, anxiety and social function as well as olfactory function in well-characterized patients with schizophrenia or schizoaffective disorder and healthy controls. RESULTS: We included 56 patients and 37 controls in our study. Patients exhibited significantly higher levels of anhedonia and anxiety than controls, and the domains were highly correlated in patients. The combination of anhedonia and anxiety more strongly predicted social dysfunction than either measure alone. Smell identification was differentially related to the symptoms, with better performance predicting less anhedonia but more social fear in male patients. LIMITATIONS: The use of self-report measures precludes differentiation between recollected or recounted experience. Aside from smell identification and odour threshold, additional measures of olfaction may be considered for future studies. CONCLUSION: Anhedonia and anxiety were strongly correlated and both negatively impacted social function. The olfactory biomarker results support the conclusion that these domains are separate. Social function in patients with schizophrenia may improve with interventions for anxiety, even in the presence of marked negative symptoms.

BACKGROUND: The consumption of sweetened beverages, refined foods, and pastries has been shown to be associated with an increased risk of depression in longitudinal studies. However, any influence that refined carbohydrates has on mood could be commensurate with their proportion in the overall diet; studies are therefore needed that measure overall intakes of carbohydrate and sugar, glycemic index (GI), and glycemic load. OBJECTIVE: We hypothesized that higher dietary GI and glycemic load would be associated with greater odds of the prevalence and incidence of depression. DESIGN: This was a prospective cohort study to investigate the relations between dietary GI, glycemic load, and other carbohydrate measures (added sugars, total sugars, glucose, sucrose, lactose, fructose, starch, carbohydrate) and depression in postmenopausal women who participated in the Women's Health Initiative Observational Study at baseline between 1994 and 1998 (n = 87,618) and at the 3-y follow-up (n = 69,954). RESULTS: We found a progressively higher dietary GI to be associated with increasing odds of incident depression in fully adjusted models (OR for the fifth vs. first quintile: 1.22; 95% CI: 1.09, 1.37), with the trend being statistically significant (P = 0.0032). Progressively higher consumption of dietary added sugars was also associated with increasing odds of incident depression (OR for the fifth vs. first quintile: 1.23; 95% CI: 1.07, 1.41; P-trend = 0.0029). Higher consumption of lactose, fiber, nonjuice fruit, and vegetables was significantly associated with lower odds of incident depression, and nonwhole/refined grain consumption was associated with increased odds of depression. CONCLUSIONS: The results from this study suggest that high-GI diets could be a risk factor for depression in postmenopausal women. Randomized trials should be undertaken to examine the question of whether diets rich in low-GI foods could serve as treatments and primary preventive measures for depression in postmenopausal women. The Women's Health Initiative is registered at clinicaltrials.gov as NCT00000611.