Melbourne School of Psychological Sciences - Research Publications
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Hippocampal shape variations at term equivalent age in very preterm infants compared with term controls: Perinatal predictors and functional significance at age 7
The hippocampus undergoes rapid growth and development in the perinatal months. Infants born very pre-term (VPT) are vulnerable to hippocampal alterations, and can provide a model of disturbed early hippocampal development. Hippocampal shape alterations have previously been associated with memory impairment, but have never been investigated in infants. The aims of this study were to determine hippocampal shape differences between 184 VPT infants (<30 weeks' gestation or <1250 g at birth) and 32 full-term infants, effects of perinatal factors, and associations between infant hippocampal shape and volume, and 7 year verbal and visual memory (California Verbal Learning Test - Children's Version and Dot Locations). Infants underwent 1.5 T magnetic resonance imaging at term equivalent age. Hippocampi were segmented, and spherical harmonics-point distribution model shape analysis was undertaken. VPT infants' hippocampi were less infolded than full-term infants, being less curved toward the midline and less arched superior-inferiorly. Straighter hippocampi were associated with white matter injury and postnatal corticosteroid exposure. There were no significant associations between infant hippocampal shape and 7 year memory measures. However, larger infant hippocampal volumes were associated with better verbal memory scores. Altered hippocampal shape in VPT infants at term equivalent age may reflect delayed or disrupted development. This study provides further insight into early hippocampal development and the nature of hippocampal abnormalities in prematurity.
Effects of reward and punishment on brain activations associated with inhibitory control in cigarette smokers
Background and aimsSusceptibility to use of addictive substances may result, in part, from a greater preference for an immediate small reward relative to a larger delayed reward or relative insensitivity to punishment. This functional magnetic resonance imaging (fMRI) study examined the neural basis of inhibiting an immediately rewarding stimulus to obtain a larger delayed reward in smokers. We also investigated whether punishment could modulate inhibitory control.DesignThe Monetary Incentive Go/NoGo (MI-Go/NoGo) task was administered that provided three types of reward outcomes contingent upon inhibitory control performance over rewarding stimuli: inhibition failure was either followed by no monetary reward (neutral condition), a small monetary reward with immediate feedback (reward condition) or immediate monetary punishment (punishment condition). In the reward and punishment conditions, successful inhibitory control resulted in larger delayed rewards.SettingCommunity sample of smokers in the Melbourne (Australia) area.ParticipantsNineteen smokers were compared with 17 demographically matched non-smoking controls.MeasurementsAccuracy, reaction times and brain activation associated with the MI-Go/NoGo task.FindingsSmokers showed hyperactivation in the right insula (P<0.01), inferior and middle frontal gyrus (P<0.01), dorsolateral prefrontal cortex (P=0.001) and inferior parietal lobe (P<0.01) both during inhibition of an immediately rewarding stimulus to obtain a larger delayed reward, and during inhibition of neutral stimuli. Group differences in brain activity were not significant in the punishment condition in the right insula and dorsolateral prefrontal cortex, most probably as a result of increased activation in non-smoking controls.ConclusionsCompared with non-smokers, smokers showed increased neural activation when resisting immediately rewarding stimuli and may be less sensitive to punishment as a strategy to increase control over rewarding stimuli.
Positive parenting predicts the development of adolescent brain structure: A longitudinal study
Little work has been conducted that examines the effects of positive environmental experiences on brain development to date. The aim of this study was to prospectively investigate the effects of positive (warm and supportive) maternal behavior on structural brain development during adolescence, using longitudinal structural MRI. Participants were 188 (92 female) adolescents, who were part of a longitudinal adolescent development study that involved mother-adolescent interactions and MRI scans at approximately 12 years old, and follow-up MRI scans approximately 4 years later. FreeSurfer software was used to estimate the volume of limbic-striatal regions (amygdala, hippocampus, caudate, putamen, pallidum, and nucleus accumbens) and the thickness of prefrontal regions (anterior cingulate and orbitofrontal cortices) across both time points. Higher frequency of positive maternal behavior during the interactions predicted attenuated volumetric growth in the right amygdala, and accelerated cortical thinning in the right anterior cingulate (males only) and left and right orbitofrontal cortices, between baseline and follow up. These results have implications for understanding the biological mediators of risk and protective factors for mental disorders that have onset during adolescence.
Development of temperamental effortful control mediates the relationship between maturation of the prefrontal cortex and psychopathology during adolescence: A 4-year longitudinal study
This study investigated the relationship between the development of effortful control (EC), a temperamental measure of self-regulation, and concurrent development of three regions of the prefrontal cortex (anterior cingulate cortex, ACC; dorsolateral prefrontal cortex, vlPFC; ventrolateral prefrontal cortex, dlPFC) between early- and mid-adolescence. It also examined whether development of EC mediated the relationship between cortical maturation and emotional and behavioral symptoms. Ninety-two adolescents underwent baseline assessments when they were approximately 12 years old and follow-up assessments approximately 4 years later. At each assessment, participants had MRI scans and completed the Early Adolescent Temperament Questionnaire-Revised, as well as measures of depressive and anxious symptoms, and aggressive and risk taking behavior. Cortical thicknesses of the ACC, dlPFC and vlPFC, estimated using the FreeSurfer software, were found to decrease over time. EC also decreased over time in females. Greater thinning of the left ACC was associated with less reduction in EC. Furthermore, change in effortful control mediated the relationship between greater thinning of the left ACC and improvements in socioemotional functioning, including reductions in psychopathological symptoms. These findings highlight the dynamic association between EC and the maturation of the anterior cingulate cortex, and the importance of this relationship for socioemotional functioning during adolescence.
Neurocognitive predictors of transition to psychosis: medium- to long-term findings from a sample at ultra-high risk for psychosis
(CAMBRIDGE UNIV PRESS, 2013-11-27)
Background. Individuals at ultra-high risk (UHR) for psychosis show reduced neurocognitive performance across domains but it is unclear which reductions are associated with transition to frank psychosis. The aim of this study was to investigate differences in baseline neurocognitive performance between UHR participants with (UHR-P) and without transition to psychosis (UHR-NP) and a healthy control (HC) group and examine neurocognitive predictors of transition over the medium to long term.Method. A sample of 325 UHR participants recruited consecutively from the Personal Assessment and Crisis Evaluation (PACE) Clinic in Melbourne and 66 HCs completed a neurocognitive assessment at baseline. The UHR group was followed up between 2.39 and 14.86 (median 6.45) years later. Cox regression was used to investigate candidate neurocognitive predictors of psychosis onset.Results. The UHR group performed more poorly than the HC group across a range of neurocognitive domains but only performance on digit symbol coding and picture completion differed between the groups. The risk of transition was only significantly associated with poorer performance on visual reproduction [hazard ratio (HR) 0.919, 95% confidence interval (CI) 0.876-0.965, p =0.001] and matrix reasoning (HR 0.938, 95% CI 0.883-0.996, p =0.037). These remained significant even after controlling for psychopathology at baseline.Conclusions. This study is the longest follow-up of an UHR sample to date. UHR status was associated with poorer neurocognitive performance compared to HCs on some tasks. Cognition at identification as UHR was not a strong predictor of risk for transition to psychosis. The results suggests the need to include more experimental paradigms that isolate discrete cognitive processes to better understand neurocognition at this early stage of illness.
Using ambiguous plaid stimuli to investigate the influence of immediate prior experience on perception
In a series of three experiments, we used an ambiguous plaid motion stimulus to explore the behavioral and electrophysiological effects of prior stimulus exposures and perceptual states on current awareness. The results showed that prior exposure to a stimulus biased toward one percept led to subsequent suppression of that percept. In contrast, in the absence of stimulus bias, prior perceptual experience can have a facilitative influence. The suppressive effects caused by the prior stimulus were found to transfer to an ambiguous plaid test stimulus rotated 180A(0) relative to the adaptation stimulus, but were abolished if (1) the ambiguous test stimulus was only rotated 90A(0) relative to the adaptation stimulus or (2) the adaptation stimulus was heavily biased toward the component grating percept. Event-related potential recordings were consistent with the involvement of visual cortical areas and suggested that the influence of recent stimulus exposure may involve recruitment of additional brain processes beyond those responsible for initial stimulus encoding. In contrast, the effects of prior and current perceptual experience appeared to depend on similar brain processes. Although the data presented here focus on vision, the work is discussed within the context of data from a parallel series of experiments in audition.
Free Thyroxine Levels After Very Preterm Birth and Neurodevelopmental Outcomes at Age 7 Years
(AMER ACAD PEDIATRICS, 2014-04-27)
BACKGROUND AND OBJECTIVES: Preterm infants commonly have transient hypothyroxinemia of prematurity after birth, which has been associated with deficits in general intellectual functioning, memory, attention, and academic achievement. However, research has predominantly focused on thyroxine levels in the first 2 weeks of life and outcomes are limited to the preschool period. Our objective was to evaluate the relationships between free thyroxine (fT(4)) levels over the first 6 weeks after very preterm (VPT) birth with cognitive functioning and brain development at age 7 years.METHODS: A total of 83 infants born VPT (< 30 weeks' gestation) had fT(4) concentrations measured postnatally and 2- and 6-week area under the curve (AUC) summary measures were calculated. Follow-up at age 7 years included a neuropsychological assessment and brain MRI. Univariable and multivariable regression modeling was used where AUC for fT(4) was the main predictor of neurodevelopmental outcome at age 7 years.RESULTS: Multivariable modeling revealed that higher, not lower, postnatal fT(4) levels (2-week AUC) were associated with poorer cognitive performances at age 7 years on tasks of verbal learning (P = .02), verbal memory (P = .03), and simple reaction time (P < .001). A similar pattern of results was found when the 6-week AUC was examined. No significant associations between postnatal fT(4) levels and brain volumes at age 7 years were identified.CONCLUSIONS: Results are contradictory to previous observations and suggest that after adjustment for confounders, higher postnatal fT(4) levels in VPT infants, rather than lower levels, may be a marker of adverse neuropsychological development in childhood.
Inspiratory-resistive loading increases the ventilatory response to arousal but does not reduce genioglossus muscle activity on the return to sleep
(AMER PHYSIOLOGICAL SOC, 2012-09-27)
Cori JM, Nicholas CL, Baptista S, Huynh I, Rochford PD, O' Donoghue FJ, Trinder JA, Jordan AS. Inspiratory-resistive loading increases the ventilatory response to arousal but does not reduce genioglossus muscle activity on the return to sleep. J Appl Physiol 113: 909-916, 2012. First published July 19, 2012; doi: 10.1152/japplphysiol.00608.2012.-Arousals from sleep are thought to predispose to obstructive sleep apnea by causing hyperventilation and hypocapnia, which reduce airway dilator muscle activity on the return to sleep. However, prior studies of auditory arousals have not resulted in reduced genioglossus muscle activity [GG-electromyogram (EMG)], potentially because airway resistance prior to arousal was low, leading to a small ventilatory response to arousal and minimal hypocapnia. Thus we aimed to increase the ventilatory response to arousal by resistive loading prior to auditory arousal and determine whether reduced GG-EMG occurred on the return to sleep. Eighteen healthy young men and women were recruited. Subjects were instrumented with a nasal mask with a pneumotachograph, an epiglottic pressure catheter, and intramuscular GG-EMG electrodes. Mask CO2 levels were monitored. Three-to 15-s arousals from sleep were induced with auditory tones after resting breathing (No-Load) or inspiratory-resistive loading (Load; average 8.4 cmH(2)O.l(-1).s(-1)). Peak minute ventilation following arousal was greater after Load than No-Load (mean +/- SE; 8.0 +/- 0.6 vs. 7.4 +/- 0.6 l/min, respectively). However, the nadir end tidal partial pressure of CO2 did not differ between Load conditions (43.1 +/- 0.6 and 42.8 +/- 0.5 mmHg, respectively), and no period of reduced GG activity occurred following the return to sleep (GG-EMG baseline, minimum after Load and No-Load = 2.9 +/- 1.2%, 3.1 +/- 1.3%, and 3.0 +/- 1.3% max, respectively). These findings indicate that the hyperventilation, which occurs following tone-induced arousal, is appropriate for the prevailing level of respiratory drive, because loading did not induce marked hypocapnia or lower GG muscle activity on the return to sleep. Whether similar findings occur following obstructive events in patients remains to be determined.
General Movements in Very Preterm Children and Neurodevelopment at 2 and 4 Years
(AMER ACAD PEDIATRICS, 2013-08-27)
OBJECTIVE: Although similar to 50% of very preterm (VP) children have neurodevelopmental impairments, early prediction of infants who will experience problems later in life remains a challenge. This study evaluated the predictive value of general movements (GM; spontaneous and endogenous movements) at 1 and 3 months' corrected age for neurodevelopment at 2 and 4 years of age in VP children.METHODS: At 1 and 3 months' corrected age, infants born,30 weeks' gestation had GM assessed as normal or abnormal. Motor, cognitive, and language development at 2 years was assessed by using the Bayley Scales of Infant and Toddler Development, Third Edition. At 4 years, cognitive and language outcomes were assessed by using the Differential Ability Scale-Second Edition and motor outcomes with the Movement Assessment Battery for Children-Second Edition; a diagnosis of cerebral palsy was documented.RESULTS: Ninety-nine VP infants were recruited, with 97% and 88% of survivors followed up at age 2 and 4 years, respectively. Abnormal GM at 1 month were associated with worse motor outcomes at 2 and 4 years but not language or cognitive outcomes. Abnormal GM at 3 months were associated with worse motor, cognitive, and language outcomes at both 2 and 4 years. Overall, GM at 1 month demonstrated better sensitivity to impairments at 2 and 4 years, whereas GM at 3 months had better specificity and were more accurate overall at distinguishing between children with and without impairment.CONCLUSIONS: Abnormal GM in VP infants, particularly at 3 months postterm, are predictive of worse neurodevelopment at ages 2 and 4 years.
Neurobehaviour between birth and 40 weeks' gestation in infants born < 30 weeks' gestation and parental psychological wellbeing: predictors of brain development and child outcomes
(BIOMED CENTRAL LTD, 2014)
Background: Infants born < 30 weeks' gestation are at increased risk of long term neurodevelopmental problems compared with term born peers. The predictive value of neurobehavioural examinations at term equivalent age in very preterm infants has been reported for subsequent impairment. Yet there is little knowledge surrounding earlier neurobehavioural development in preterm infants prior to term equivalent age, and how it relates to perinatal factors, cerebral structure, and later developmental outcomes. In addition, maternal psychological wellbeing has been associated with child development. Given the high rate of psychological distress reported by parents of preterm children, it is vital we understand maternal and paternal wellbeing in the early weeks and months after preterm birth and how this influences the parent-child relationship and children's outcomes. Therefore this study aims to examine how 1) early neurobehaviour and 2) parental mental health relate to developmental outcomes for infants born preterm compared with infants born at term.Methods/Design: This prospective cohort study will describe the neurobehaviour of 150 infants born at < 30 weeks' gestational age from birth to term equivalent age, and explore how early neurobehavioural deficits relate to brain growth or injury determined by magnetic resonance imaging, perinatal factors, parental mental health and later developmental outcomes measured using standardised assessment tools at term, one and two years' corrected age. A control group of 150 healthy term-born infants will also be recruited for comparison of outcomes. To examine the effects of parental mental health on developmental outcomes, both parents of preterm and term-born infants will complete standardised questionnaires related to symptoms of anxiety, depression and post-traumatic stress at regular intervals from the first week of their child's birth until their child's second birthday. The parent-child relationship will be assessed at one and two years' corrected age.Discussion: Detailing the trajectory of infant neurobehaviour and parental psychological distress following very preterm birth is important not only to identify infants most at risk, further understand the parental experience and highlight potential times for intervention for the infant and/or parent, but also to gain insight into the effect this has on parent-child interaction and child development.
Contribution of Brain Size to IQ and Educational Underperformance in Extremely Preterm Adolescents
(PUBLIC LIBRARY SCIENCE, 2013)
Objectives: Extremely preterm (EP) survivors have smaller brains, lower IQ, and worse educational achievement than their term-born peers. The contribution of smaller brain size to the IQ and educational disadvantages of EP is unknown. This study aimed (i) to compare brain volumes from multiple brain tissues and structures between EP-born (<28weeks) and term-born (>= 37weeks) control adolescents, (ii) to explore the relationships of brain tissue volumes with IQ and basic educational skills and whether this differed by group, and (iii) to explore how much total brain tissue volume explains the underperformance of EP adolescents compared with controls.Methods: Longitudinal cohort study of 148 EP and 132 term controls born in Victoria, Australia in 1991-92. At age 18, magnetic resonance imaging-determined brain volumes of multiple tissues and structures were calculated. IQ and educational skills were measured using the Wechsler Abbreviated Scale of Intelligence (WASI) and the Wide Range Achievement Test(WRAT-4), respectively.Results: Brain volumes were smaller in EP adolescents compared with controls (mean difference [95% confidence interval] of -5.9% [-8.0, -3.7%] for total brain tissue volume). The largest relative differences were noted in the thalamus and hippocampus. The EP group had lower IQs(-11.9 [-15.4, -8.5]), spelling(-8.0 [-11.5, -4.6]), math computation(-10.3 [-13.7, -6.9]) and word reading(-5.6 [-8.8, -2.4]) scores than controls; all p-values<0.001. Volumes of total brain tissue and other brain tissues and structures correlated positively with IQ and educational skills, a relationship that was similar for both the EP and controls. Total brain tissue volume explained between 20-40% of the IQ and educational outcome differences between EP and controls.Conclusions: EP adolescents had smaller brain volumes, lower IQs and poorer educational performance than controls. Brain volumes of multiple tissues and structures are related to IQ and educational outcomes. Smaller total brain tissue volume is an important contributor to the cognitive and educational underperformance of adolescents born EP.
Preventing academic difficulties in preterm children: a randomised controlled trial of an adaptive working memory training intervention - IMPRINT study
(BIOMED CENTRAL LTD, 2013)
Background: Very preterm children exhibit difficulties in working memory, a key cognitive ability vital to learning information and the development of academic skills. Previous research suggests that an adaptive working memory training intervention (Cogmed) may improve working memory and other cognitive and behavioural domains, although further randomised controlled trials employing long-term outcomes are needed, and with populations at risk for working memory deficits, such as children born preterm. In a cohort of extremely preterm (<28 weeks' gestation)/extremely low birthweight (<1000 g) 7-year-olds, we will assess the effectiveness of Cogmed in improving academic functioning 2 years' post-intervention. Secondary objectives are to assess the effectiveness of Cogmed in improving working memory and attention 2 weeks' , 12 months' and 24 months' post-intervention, and to investigate training related neuroplasticity in working memory neural networks 2 weeks' post-intervention.Methods/Design: This double-blind, placebo-controlled, randomised controlled trial aims to recruit 126 extremely preterm/extremely low birthweight 7-year-old children. Children attending mainstream school without major intellectual, sensory or physical impairments will be eligible. Participating children will undergo an extensive baseline cognitive assessment before being randomised to either an adaptive or placebo (non-adaptive) version of Cogmed. Cogmed is a computerised working memory training program consisting of 25 sessions completed over a 5 to 7 week period. Each training session takes approximately 35 minutes and will be completed in the child's home. Structural, diffusion and functional Magnetic Resonance Imaging, which is optional for participants, will be completed prior to and 2 weeks following the training period. Follow-up assessments focusing on academic skills (primary outcome), working memory and attention (secondary outcomes) will be conducted at 2 weeks' , 12 months' and 24 months' post-intervention.Discussion: To our knowledge, this study will be the first randomised controlled trial to (a) assess the effectiveness of Cogmed in school-aged extremely preterm/extremely low birthweight children, while incorporating advanced imaging techniques to investigate neural changes associated with adaptive working memory training, and (b) employ long-term follow-up to assess the potential benefit of improved working memory on academic functioning. If effective, Cogmed would serve as a valuable, available intervention for improving developmental outcomes for this population.