Atypical Cognitive Development Research Articles

79 Concordance Between Theorized Cognitive Profiles, Medical Risk Factors, and Clinical Diagnoses Within Preschool-Aged Children

Objective:Early childhood is recognized as a critical window of rapid cognitive development. Unfortunately, many risk factors for atypical cognitive development may occur during this period, including genetic syndromes, congenital neuroanatomical malformations, pre- or perinatal injury, and neurological and medical disorders. The impact of these risk factors on cognitive functioning may not always map onto patterns typically observed in adults. Limited literature exists on the presentation of cognitive profiles within clinical populations in the preschool developmental period. The present study aimed to evaluate whether discrete a priori cognitive profiles consistent with common neurobehavioral syndromes emerge and are distinguishable on testing in early childhood in a mixed clinical sample. We also aimed to determine if there was a consistent association between known medical risk factors and resultant cognitive profiles.Participants and Methods:Participants included 163 children aged 1-5 years (M=48.5 months, SD=12.8 months) referred for neuropsychological evaluation. The sample was predominantly male (67.5%) and White (72.9%), followed by other/mixed race (11.6%), Black (9.7%), and Latino/Hispanic (5.8%). Cognitive abilities assessed included broad intellectual abilities, verbal abilities, nonverbal abilities, attention, and executive functioning. Continuous test scores were transformed into categorical ranges of performance, with scores classified as “above average,” “average,” “below average,” or “extremely low” to allow for profile classification. Theoretical clinical profiles consistent with common neurobehavioral syndromes were determined a priori by consensus among three authors (JK, AH, LM). Chi square tests of independence were conducted to compare membership across neurobehavioral diagnostic groups, clinical profile groups, and medical groups.Results:Based on cognitive data, 55.2% of the sample (n=90) was classified as Global Developmental Delay/Intellectual Disability, 19.6% (GDD/ID; n=32) was classified asLanguage Disorder, and 18.4% (n=30) was classified as Typical Cognitive Development. 4.3% (n=7) of the sample was classified as Attention-Deficit/Hyperactivity Disorder (ADHD), and 2.5% (n=4) was classified as Nondominant Hemisphere Dysfunction. As hypothesized, cognitive profile group membership was consistent with diagnostic impressions, as actual clinical diagnoses of Language Disorder, ADHD, GDD/ID, or a classification of typical cognitive development were significantly associated with theorized cognitive profile based on test performance alone (x2 (1,20) = 147.29, p < .001). Cognitive profile group membership was also significantly associated with referral source (1,28) = 62.88, p < .001) and the presence of a neurological disorder (1,4) = 14.64, p =.006).Conclusions:Findings support the presence of specific theorized cognitive profiles in preschoolers in a mixed clinical sample. Specifically, GDD/ID, Language Disorder, and typical cognitive development are discrete and consistently distinguishable cognitive profiles in this age range. Early life neurological risk factors are also significantly related to cognitive profile membership, suggesting that these factors may be useful in predicting cognitive development even in very young children. Future work is needed to examine the consistency of these profiles over time and their predictive value in estimating subsequent development, and the possibility of discriminating unique cognitive profiles for specific medical conditions in preschoolers.

The Detection of Early Reading Performance and Its Relationship with Biopsychosocial Risk Factors in the Study of Learning Difficulties.

The study of the multiple processes involved in learning how to read can contribute towards the early detection of good and bad readers. However, it is necessary to take into consideration different biopsychosocial risk factors (pre- and perigestational, neonatal, medical, developmental and family-related) that may have a significant impact on neurodevelopment, producing atypical cognitive development that could lead to the presence of reading difficulties. The objective of this study was to identify the main psycholinguistic abilities involved in the early reading performance and analyse their relationship to biopsychosocial risk factors. A total of 110 subjects between the ages of 4 and 7 years old and enrolled in state-run schools in Spain participated in the study. Significant correlations were found between different psycholinguistic abilities and certain biopsychosocial risk factors (having had hyperbilirubinemia, having obtained a score lower than 9 on the Apgar test, having had language problems or a sibling with dyslexia). This relationship should be taken into account in the study of learning difficulties as a potential indicator to predict later reading development and even the presence of developmental dyslexia.

Adaptive Cognitive Control in Prematurely Born Children: An HD-EEG Investigation.

Preterm birth is a neurodevelopmental risk condition often associated with cognitive control (CC) impairment. Recent evidence showed that CC can be implicitly adapted through associative learning. In the present study we investigated the ability to flexibly adjust CC as a function of implicit stimulus-response temporal regularities in preterm (PT; N = 21; mean age 8 ± 1.3 years; gestational age 30 ± 18.5 weeks) and full-term (FT; N = 20; mean age 8 ± 1.3 years) school-age children. All children underwent an HD-EEG recording while undergoing the Dynamic Temporal Prediction (DTP) task, a simple S1–S2 detection task purposely designed to generate local-global temporal predictability of imperative stimuli. The Wisconsin card sorting test (WCST) was administered to measure explicit CC. The PT group showed more premature and slower (DTP) as well as perseverative (WCST) responses than the FT group. Moreover, pre-terms showed poor adaptive CC as revealed by less efficient global response-speed adjustment. This behavioral pattern was mirrored by a reduced and less sensitive to global manipulation anticipatory Contingent Negative Variation (CNV) and by different cortical source recruitment. These findings suggest that implicit CC may be a reliable endophenotypic marker of atypical cognitive development associated with preterm birth.

Tbx1, a gene encoded in 22q11.2 copy number variant, is a link between alterations in fimbria myelination and cognitive speed in mice

Copy number variants (CNVs) have provided a reliable entry point to identify the structural correlates of atypical cognitive development. Hemizygous deletion of human chromosome 22q11.2 is associated with impaired cognitive function; however, the mechanisms by which the CNVs contribute to cognitive deficits via diverse structural alterations in the brain remain unclear. This study aimed to determine the cellular basis of the link between alterations in brain structure and cognitive functions in mice with a heterozygous deletion of Tbx1, one of the 22q11.2-encoded genes. Ex vivo whole-brain diffusion-tensor imaging (DTI)–magnetic resonance imaging (MRI) in Tbx1 heterozygous mice indicated that the fimbria was the only region with significant myelin alteration. Electron microscopic and histological analyses showed that Tbx1 heterozygous mice exhibited an apparent absence of large myelinated axons and thicker myelin in medium axons in the fimbria, resulting in an overall decrease in myelin. The fimbria of Tbx1 heterozygous mice showed reduced mRNA levels of Ng2, a gene required to produce oligodendrocyte precursor cells. Moreover, postnatal progenitor cells derived from the subventricular zone, a source of oligodendrocytes in the fimbria, produced fewer oligodendrocytes in vitro. Behavioral analyses of these mice showed selectively slower acquisition of spatial memory and cognitive flexibility with no effects on their accuracy or sensory or motor capacities. Our findings provide a genetic and cellular basis for the compromised cognitive speed in patients with 22q11.2 hemizygous deletion.

Long-term effects of early treatment with SSRIs on cognition and brain development in individuals with 22q11.2 deletion syndrome

Cognitive deficits in individuals at risk of psychosis represent a significant challenge for research, as current strategies for symptomatic treatment are often ineffective. Recent studies showed that atypical cognitive development predicts the occurrence of psychotic symptoms. Additionally, abnormal brain development is known to predate clinical manifestations of psychosis. Therefore, critical developmental stages may be the best period for early interventions expected to prevent cognitive decline and protect brain maturation. However, it is challenging to identify and treat individuals at risk of psychosis in the general population before the onset of the first psychotic symptoms. 22q11.2 deletion syndrome (22q11DS), the neurogenetic disorder with the highest genetic risk for schizophrenia, provides the opportunity to prospectively study the development of subjects at risk for psychosis. In this retrospective cohort study, we aimed to establish if early treatment with SSRIs in children and adolescents with 22q11DS was associated with long-term effects on cognition and brain development. We included 98 participants with a confirmed diagnosis of 22q11DS followed up 2–4 times (age range: 10–32). Thirty subjects without psychiatric disorders never received psychotropic medications, thirty had psychotic symptoms but were not treated with SSRIs, and 38 received SSRIs treatment. An increase in IQ scores characterized the developmental trajectories of participants receiving treatment with SSRIs, even those with psychotic symptoms. The thickness of frontal regions and hippocampal volume were also relatively increased. The magnitude of the outcomes was inversely correlated to the age at the onset of the treatment. We provide preliminary evidence that early long-term treatment with SSRIs may attenuate the cognitive decline associated with psychosis in 22q11DS and developmental brain abnormalities.

Relations entre particularités sensorielles et imitation chez les enfants TSA de 3 à 5 ans

ObjectiveAutism Spectrum Disorder (ASD) is a neuro-developmental disorder resulting on atypical cognitive development characterized by communication and language disorders, restricted behaviors and sensory abnormalities, present in the most of subjects. These abnormalities cause many disorders, including motor and sensory-motor troubles. Imitation, which is characterized by the coordination between a visually perceived behavior and actively produced behavior, is in this perspective, a sophisticated sensory-motor coordination. It is strongly troubled in children with ASD, with significant negative effects on their future socio-communicative development. The aim of this research is to determine if imitation disorders increase with the number of sensory abnormalities. MethodsTwenty-two children (18 boys), aged from 3 to 5 years, were included in this study. Autism was assessed by the Chilhood Autism Rating Scale (CARS) and the Autism Diagnostic Observation schedule (ADOS). Dunn's Sensory and Revised Perceptual Profile was administered to determine the sensory profile for five senses: visual, auditive, tactile, proprioceptive and vestibular. Four types of imitation were evaluated: facial, motor, vocal and object. Statistical analyzes were conducted on the different scores obtained. ResultsAll children with autism have sensory abnormalities and imitation disorders. The more the children have sensory particularities, especially visual, the more their imitation skills are weak, especially in facial imitation. Imitation on object, conversely, seems less impacted. ConclusionThe sensory abnormalities could constitute a screen to the realization of the imitative tasks, by preventing the children to reach the social dimension of the imitation for example. These results illustrate the need to take into account these sensory features in specific care.

Shifting preferences for choice-making opportunities through histories of differential reinforcer quality.

Children of both typical and atypical cognitive development tend to prefer contexts in which their behavior results in a choice of reinforcers rather than a single reinforcer, even when the reinforcer accessed is identical across conditions. The origin of this preference has been attributed speculatively to behavioral histories in which choice making tends to be associated with differentially beneficial outcomes. Few studies have evaluated this claim, and those that have, have yielded mixed results. We provided five preschool-aged children experiences in which choice-making and no-choice contexts were differentially associated with higher preference and larger magnitude reinforcers, and we assessed changes in their preference for choice and no-choice contexts in which outcomes were equated. These conditioning experiences resulted in consistent and replicable shifts in child preference, indicating that preference for choice is malleable through experience.

Inhibitory Control of Attention: Difference versus Developmental Theory. Findings in Mild Intellectual Disability and ADHD

We investigate the relationship between inhibition and cognition in developmental age adding values for the understanding of EFs. The aim of this study was to examine the development of EFs by comparing children of different clinical populations: children with a Mild Intellectual Disability (MID) with atypical cognitive development and children with ADHD inattentive subtype with impaired inhibition development. Results obtained suggest that only a subgroup of MID has an inhibition deficit (not overlapping with ADHD). So, the data seemed to support the hypothesis that EFs, even when impaired, could follow different pathways of development, partially independent from intelligence. Moreover, our findings seemed to fit with the hypothesis that the diagnosis of intellectual disability include different neuropsychological phenotypes.

Cognitive Clusters in Specific Learning Disorder

The heterogeneity among children with learning disabilities still represents a barrier and a challenge in their conceptualization. Although a dimensional approach has been gaining support, the categorical approach is still the most adopted, as in the recent fifth edition of the Diagnostic and Statistical Manual of Mental Disorders. The introduction of the single overarching diagnostic category of specific learning disorder (SLD) could underemphasize interindividual clinical differences regarding intracategory cognitive functioning and learning proficiency, according to current models of multiple cognitive deficits at the basis of neurodevelopmental disorders. The characterization of specific cognitive profiles associated with an already manifest SLD could help identify possible early cognitive markers of SLD risk and distinct trajectories of atypical cognitive development leading to SLD. In this perspective, we applied a cluster analysis to identify groups of children with a Diagnostic and Statistical Manual–based diagnosis of SLD with similar cognitive profiles and to describe the association between clusters and SLD subtypes. A sample of 205 children with a diagnosis of SLD were enrolled. Cluster analyses (agglomerative hierarchical and nonhierarchical iterative clustering technique) were used successively on 10 core subtests of the Wechsler Intelligence Scale for Children–Fourth Edition. The 4-cluster solution was adopted, and external validation found differences in terms of SLD subtype frequencies and learning proficiency among clusters. Clinical implications of these findings are discussed, tracing directions for further studies.

Why parametric measures are critical for understanding typical and atypical cognitive development.

Children's cognitive abilities improve significantly over childhood and adolescence. We know from behavioral research that core cognitive processes such as working memory and mental attention improve significantly across development. Functional magnetic resonance imaging (fMRI) allows for investigating the typically developing, living brain in action. In the last twenty years we have learned a great deal about brain correlates associated with how adults hold and manipulate information in mind, however, neurocognitive correlates across development remain inconsistent. We present developmental fMRI findings on cognitive processes such as working memory and mental attention and discuss methodological and theoretical issues in the assessment of cognitive limitations in the visual spatial and verbal domains. We also review data from typical and atypical development and emphasize the unique contribution parametric measures can make in understanding neurocognitive correlates of typical and atypical development.

Building Bridges: Cognitive Development in Typical and Atypical Populations

Most research reported in the Journal of Cognition and Development focuses on typically developing children—those who are following what is assumed to be the most common path. This special issue was designed to foster a dialogue between cognitive developmentalists who work on typical development and those who work on atypical development, with the goal of illustrating how recent findings can advance thinking in both fields. The 6 target articles and 2 commentaries in this special issue provide a compelling demonstration of the symbiotic nature of the study of typical and atypical cognitive development.

Characteristics of detection of the general direction of movement of visual objects by preschool-age children with typical and atypical cognitive development

The specifics of functioning of two channels for processing visual information, the magnocellular and parvocellular ones, in preschool children with normal and impaired cognitive development have been studied. Children with delayed psychological development have been found to have a diminished activity in the magnocellular channel due to weakening of the mechanism responsible for assessing the temporal parameters of the visual input. At the same time, children displaying a spectrum of infantile autism syndromes complicated by a delayed psychological development and mental retardation have a pronounced deficit in information processing in both channels of the visual system, manifested in an impaired ability to assess the direction of movement in terms of both temporal and spatial characteristics of the objects. The degree of this impairment is correlated with both the severity of the particular neurological disorder and the level of speech development of the child.

Neuroimaging and neurodevelopmental outcome of preterm infants with a periventricular haemorrhagic infarction located in the temporal or frontal lobe

The aim of the study was to compare clinical and neuroimaging characteristics and neurodevelopmental outcome in preterm infants with a periventricular haemorrhagic infarction (PVHI) located in the temporal or frontal periventricular white matter. The study was a retrospective hospital-based study of preterm infants with a frontal PVHI (n=21; 11 males, 10 females; mean birthweight 1527g; mean gestational age 30.3wks) or temporal PVHI (n=13; five males, eight females; mean birthweight 1205g; mean gestational age 30.2wks) admitted to the neonatal intensive care unit between 1990 and 2012. The clinical course, results of neuroimaging studies, and neurodevelopmental outcomes of preterm infants with a gestational age less than 34 weeks with a confirmed PVHI on early cranial ultrasonography and/or magnetic resonance imaging were reviewed. For assessment of neurodevelopmental outcome we used the Griffiths Mental Development Scales, the Movement Assessment Battery for Children, the Gross Motor Function Classification System, the Wechsler Preschool and Primary Scale of Intelligence, the Child Behavior Checklist, and ophthalmological assessment. An unfavourable neurodevelopmental outcome was defined as moderately or severely atypical neurological examination during the last visit: presence of cerebral palsy, epilepsy, a hearing or visual impairment, and/or atypical cognitive development (Griffiths Mental Development Scales developmental quotient or Wechsler Preschool and Primary Scale of Intelligence <85). Unfavourable outcome was observed in 12 out of 13 children with a temporal PVHI compared with six out of 21 children with a frontal PVHI (p=0.002). Only one of the included infants with a PVHI in the temporal white matter developed cerebral palsy, which was due to a parietal PVHI in the contralateral hemisphere. Cognitive impairment was noted in seven infants with a frontal PVHI and five with a temporal PVHI. There were more infants with a temporal PVHI who developed visual impairment (n=5) or behavioural problems (n=7) compared with those with a frontal PVHI (visual impairment (n=2), behavioural problems (n=3). PVHI located in the temporal or frontal lobe is almost invariably related to a typical motor outcome, but carries a risk of cognitive, behavioural, and visual problems, especially in infants with a PVHI located in the temporal lobe.

White matter and development in children with an autism spectrum disorder

Recent research suggests that brain development follows an abnormal trajectory in children with autism spectrum disorders (ASD). The current study examined changes in diffusivity with age within defined white matter tracts in a group of typically developing children and a group of children with an ASD, aged 6 to 14 years. Age by group interactions were observed for frontal, long distant, interhemispheric and posterior tracts, for longitudinal, radial and mean diffusivity, but not for fractional anisotropy. In all cases, these measures of diffusivity decreased with age in the typically developing group, but showed little or no change in the ASD group. This supports the hypothesis of an abnormal developmental trajectory of white matter in this population, which could have profound effects on the development of neural connectivity and contribute to atypical cognitive development in children with ASD.

FMRI and MEG in the study of typical and atypical cognitive development

The tremendous changes in brain structure over childhood are critical to the development of cognitive functions. Neuroimaging provides a means of linking these brain-behaviour relations, as task protocols can be adapted for use with young children to assess the development of cognitive functions in both typical and atypical populations. This paper reviews some of our research using magnetoencephalography (MEG) and functional MRI (fMRI) in the study of cognitive development, with a focus on frontal lobe functions. Working memory for complex abstract patterns showed clear development in terms of the recruitment of frontal regions, seen with fMRI, with indications of strategy differences across the age range, from 6 to 35 years of age. Right hippocampal involvement was also evident in these n-back tasks, demonstrating its involvement in recognition in simple working memory protocols. Children born very preterm (7 to 9 years of age) showed reduced fMRI activation particularly in the precuneus and right hippocampal regions relative to control children. In a large normative n-back study (n=90) with upright and inverted faces, MEG data also showed right hippocampal activation that was present across the age range; frontal sources were evident only from 10 years of age. Other studies have investigated the development of set shifting, an executive function that is often deficit in atypical populations. fMRI showed recruitment of frontal areas, including the insula, that have significantly different patterns in children (7 to 14 years of age) with autism spectrum disorder compared to typically developing children, indicating that successful performance implicated differing strategies in these two groups of children. These types of studies will help our understanding of both normal brain-behaviour development and cognitive dysfunction in atypically developing populations.

Interval Timing Deficits and Abnormal Cognitive Development

Interval Timing Deficits and Abnormal Cognitive Development

Electroencephalogram Discharges in Atypical Cognitive Development

To investigate the significance of electroencephalogram (EEG) discharges and their treatment, we retrospectively reviewed the charts of 22 children with atypical cognitive development that did not respond to standard educational therapy and demonstrated discharges on EEG. Most children demonstrated no obvious symptoms of seizures, and developmental regression and/or fluctuations were uncommon. The majority of children demonstrated a language and attention disorder and autism symptomatology and had multifocal discharges on EEGs. Of the 20 patients treated with antiepileptic medications, 70% demonstrated definite improvement within 1 clinic visit. This study suggests that children with EEG discharges and developmental cognitive disorders demonstrate a unique pattern of symptomatology and discharges on EEG. This study suggests that children with developmental cognitive disorders that do not respond to standard therapy may benefit from screening with an EEG and a trial of antiepileptic mediation if discharges are detected.

Typical and atypical development of functional human brain networks: insights from resting-state fMRI

Over the past several decades, structural MRI studies have provided remarkable insights into human brain development by revealing the trajectory of gray and white matter maturation from childhood to adolescence and adulthood. In parallel, functional MRI studies have demonstrated changes in brain activation patterns accompanying cognitive development. Despite these advances, studying the maturation of functional brain networks underlying brain development continues to present unique scientific and methodological challenges. Resting-state fMRI (rsfMRI) has emerged as a novel method for investigating the development of large-scale functional brain networks in infants and young children. We review existing rsfMRI developmental studies and discuss how this method has begun to make significant contributions to our understanding of maturing brain organization. In particular, rsfMRI has been used to complement studies in other modalities investigating the emergence of functional segregation and integration across short and long-range connections spanning the entire brain. We show that rsfMRI studies help to clarify and reveal important principles of functional brain development, including a shift from diffuse to focal activation patterns, and simultaneous pruning of local connectivity and strengthening of long-range connectivity with age. The insights gained from these studies also shed light on potentially disrupted functional networks underlying atypical cognitive development associated with neurodevelopmental disorders. We conclude by identifying critical gaps in the current literature, discussing methodological issues, and suggesting avenues for future research.

Special Issue on Cognitive Neuroscience Studies of Persons With Intellectual and Developmental Disabilities

Scientists in the now well-established field of cognitive neuroscience have made significant progress in elucidating the neural substrates and cognitive processing underpinnings of a wide range of cognitive functions. However, its focus has been predominantly on typical adult function; much less attention has been given to typical and atypical development. However, cognitive neuroscientific methods hold considerable promise for significantly advancing explanations for the basis for many conditions that produce intellectual and developmental disabilities. Also, because of their neurobiological and mechanistic strengths, these methods are likely to lead to rapid progress towards a range of interventions. In keeping with the AJMR editorial board's goal of encouraging publication of relevant articles from cognitive neuroscience, we are pleased to announce a call for submissions for the Special Issue on Cognitive Neuroscience Studies. The purpose of this special issue is to provide a rare opportunity to present a collection of papers whose authors attempt to specify the neurocognitive basis of functional impairments associated with intellectual or developmental disabilities. We hope that these papers will highlight the promise of cognitive neuroscience methods for research into atypical cognitive development more generally.The Special Issue on Cognitive Neuroscience Studies will primarily contain (a) original reports of empirical research that apply some combination of experimental cognitive processing, computational modeling, neuroimaging, genetic/genomic, and other relevant methods to the analysis and explanation of intellectual or developmental disabilities. However, it may also include (b) reviews of literature in which investigators critique, evaluate, and summarize the strengths and weakness of the cognitive neuroscience methods for research into intellectual and developmental disabilities; and (c) discussions of standards for research design, methods, and evidence synthesis that relate to the special requirements of cognitive neuroscience investigations into intellectual and developmental disabilities.Submissions for this special issue are due by December 15, 2008. In addition to the topical guidelines described above, manuscripts should conform to the length and format guidelines for regular submissions to AJMR. All submissions will be peer-reviewed following current AJMR procedures and policies. Please specify in your submission cover letter whether you would like your manuscript to be considered for the Special Issue on Cognitive Neuroscience Studies.Tony J. Simon (tjsimon@ucdavis.edu) will serve as editor of the special issue. Inquiries about guidelines and submissions may be addressed to him directly.

Special Issue on Cognitive Neuroscience Studies of Persons With Intellectual and Developmental Disabilities

Scientists in the now well-established field of cognitive neuroscience have made significant progress in elucidating the neural substrates and cognitive processing underpinnings of a wide range of cognitive functions. However, its focus has been predominantly on typical adult function; much less attention has been given to typical and atypical development. However, cognitive neuroscientific methods hold considerable promise for significantly advancing explanations for the basis for many conditions that produce intellectual and developmental disabilities. Also, because of their neurobiological and mechanistic strengths, these methods are likely to lead to rapid progress towards a range of interventions. In keeping with the AJMR editorial board's goal of encouraging publication of relevant articles from cognitive neuroscience, we are pleased to announce a call for submissions for the Special Issue on Cognitive Neuroscience Studies. The purpose of this special issue is to provide a rare opportunity to present a collection of papers whose authors attempt to specify the neurocognitive basis of functional impairments associated with intellectual or developmental disabilities. We hope that these papers will highlight the promise of cognitive neuroscience methods for research into atypical cognitive development more generally.The Special Issue on Cognitive Neuroscience Studies will primarily contain (a) original reports of empirical research that apply some combination of experimental cognitive processing, computational modeling, neuroimaging, genetic/genomic, and other relevant methods to the analysis and explanation of intellectual or developmental disabilities. However, it may also include (b) reviews of literature in which investigators critique, evaluate, and summarize the strengths and weakness of the cognitive neuroscience methods for research into intellectual and developmental disabilities; and (c) discussions of standards for research design, methods, and evidence synthesis that relate to the special requirements of cognitive neuroscience investigations into intellectual and developmental disabilities.Submissions for this special issue are due by December 15, 2008. In addition to the topical guidelines described above, manuscripts should conform to the length and format guidelines for regular submissions to AJMR. All submissions will be peer-reviewed following current AJMR procedures and policies. Please specify in your submission cover letter whether you would like your manuscript to be considered for the Special Issue on Cognitive Neuroscience Studies.Tony J. Simon (tjsimon@ucdavis.edu) will serve as editor of the special issue. Inquiries about guidelines and submissions may be addressed to him directly.