Papers by Gerry A Stefanatos, D.Phil.
Cambridge University Press eBooks, Nov 5, 2012
Clinical Neurophysiology, 1997
This study investigated steady-state auditory evoked responses to pulsed frequency modulations (F... more This study investigated steady-state auditory evoked responses to pulsed frequency modulations (FM) of a continuous tone in normal children ranging in age from 6 to 12 years. We examined variations in response amplitude and phase as a function of age, recording site, and FM pulse duration. The surface topography of these evoked potentials suggested a relatively broad distribution with maximal responses observed at frontal electrode sites, smaller responses from parietal leads and the smallest responses were evident at the temporal lobe placements. Response parameters varied significantly as a function of pulse duration. Fifty milliseconds pulses elicited responses that were on average 20% larger than 100 ms FM pulses. Mean phase differences suggested that responses to the 100 ms pulses also lagged behind responses to the 50 ms pulses by the equivalent of 20 ms. There were no significant age-related variations in response amplitude. Phase varied with age only in response to the 50 ms FM pulses. The findings indicated that steady-state responses are sensitive to temporal parameters of frequency change present in pulsed modulations. The possibility is raised that this paradigm may be clinically useful in detecting dysfunction of specialized auditory mechanisms involved in frequency modulation analysis.
Perceptual and Motor Skills, Apr 1, 1998
7 girls and 5 boys, ranging in age from 7 to 12 years, participated in the pilot testing of a men... more 7 girls and 5 boys, ranging in age from 7 to 12 years, participated in the pilot testing of a mental rotation task developed for use in a comprehensive test battery of visuoperceptual abilities. Two asymmetric, three-dimensional objects were constructed from wood strips such that one object was the mirror-image of the other. Black and white photographs were taken of these objects in various spatial orientations along a horizontal plane. 16 photographs depicted the object right-side-up and in 16 the object was upside-down (rotated 180° in the vertical plane). These photographs were presented to the children who were asked to match each with the corresponding object. Analysis indicated correct judgements of the right-side-up images occurred more frequently than the upside-down images ( t11=4.73, p
PubMed, 1998
We report three children with autistic spectrum disorders who underwent upper gastrointestinal en... more We report three children with autistic spectrum disorders who underwent upper gastrointestinal endoscopy and intravenous administration of secretin to stimulate pancreaticobiliary secretion. All three had an increased pancreaticobiliary secretory response when compared with nonautistic patients (7.5 to 10 mL/min versus 1 to 2 mL/min). Within 5 weeks of the secretin infusion, a significant amelioration of the children's gastrointestinal symptoms was observed, as was a dramatic improvement in their behavior, manifested by improved eye contact, alertness, and expansion of expressive language. These clinical observations suggest an association between gastrointestinal and brain function in patients with autistic behavior.
Neuropsychology Review, Oct 28, 2008
A significant proportion of children diagnosed with Autistic Spectrum Disorder experience a devel... more A significant proportion of children diagnosed with Autistic Spectrum Disorder experience a developmental regression characterized by a loss of previously-acquired skills. This may involve a loss of speech or social responsitivity, but often entails both. This paper critically reviews the phenomena of regression in autistic spectrum disorders, highlighting the characteristics of regression, age of onset, temporal course, and long-term outcome. Important considerations for diagnosis are discussed and multiple etiological factors currently hypothesized to underlie the phenomenon are reviewed. It is argued that regressive autistic spectrum disorders can be conceptualized on a spectrum with other regressive disorders that may share common pathophysiological features. The implications of this viewpoint are discussed.
Cambridge University Press eBooks, Oct 11, 2012
Annals of the New York Academy of Sciences, Jan 25, 2006
Objective: Sports-related concussions are associated with both acute and long-term consequences. ... more Objective: Sports-related concussions are associated with both acute and long-term consequences. Past work has identified novel risk factors and modifiers for concussions, including mood and neuropsychiatric disorders. Attention Deficit Hyperactivity Disorder (ADHD) is a common neuropsychiatric disorder that may also contribute to concussion risk, although no study has examined this possibility. Methods: One hundred and thirty-nine NCAA Division-I athletes at Kent State University (KSU) self-reported a history of prior concussion and diagnostic history of ADHD as part of a larger concussion management programme at KSU. Results: ADHD was prevalent (10.1%) and 18.0% of the sample reported a prior history of at least one concussion injury. 50.4% of athletes with ADHD reported a history of at least one prior concussion vs 14.4% of athletes without ADHD, which represented a significant difference (p50.01). Analyses showed that athletes with ADHD were more likely to report a past history of concussions than those without ADHD (F (1,133) ¼ 4.31, p ¼ 0.04). Conclusion: ADHD is prevalent in NCAA Division-I athletes and associated with history of past concussions. If replicated, these findings could have important implications in the prevention and management of concussions in athletes with ADHD.
Seminars in Speech and Language, Aug 1, 2008
Word deafness is an intriguing neurological syndrome characterized by severe difficulties in the ... more Word deafness is an intriguing neurological syndrome characterized by severe difficulties in the ability to understand or reproduce spoken language with otherwise intact speech production and nonauditory language comprehension. The disorder is of significant theoretical importance because it putatively supports the modularity of speech recognition from more central language computational networks. However, the specificity and functional locus of the processing disturbances resulting in word deafness remains unclear. This article discusses the nature and potential treatment of word deafness, with particular reference to a detailed case study (neuropsychological, neuroimaging, and event-related potential) of an adult case of Landau-Kleffner syndrome. The findings in this case suggested temporal lobe pathophysiology involving cortical mechanisms concerned with temporal processing of rapid frequency changes in sound. We propose that these deficits may impede the analysis of linguistically important transitional frequency cues in speech and account for the profound difficulties in understanding and producing speech. The implications of these findings for approaches to the treatment of word deafness are discussed.
Annals of the New York Academy of Sciences, Jun 1, 1993
Clinical Neuropsychologist, Aug 1, 2011
Landau-Kleffner syndrome (LKS) is a childhood disorder characterized by an acquired aphasia that ... more Landau-Kleffner syndrome (LKS) is a childhood disorder characterized by an acquired aphasia that emerges in association with epileptiform electroencephalographic abnormalities. The language loss is often characterized by a severe disturbance of auditory language comprehension (verbal auditory agnosia) combined with a substantial disruption of expressive language. Comorbid behavioral disturbances commonly involve hyperactivity and attentional problems but sometimes encompass a more pervasive pattern of difficulties resembling an autism spectrum disorder. Now one the most frequently described forms of acquired aphasia in children, LKS has had a profound influence on both neurological practice and cognitive neuroscience. Here, we review current conceptualizations of LKS, consider its pleomorphic manifestations and discuss existing and future diagnostic issues and dilemmas. The potential relevance of LKS to understanding other disorders, including autistic regression, is considered.
Clinical Psychology Review, 1990
Journal of The International Neuropsychological Society, Mar 20, 2007
An Introduction to the Event-Related Potential Technique (Cognitive Neuroscience), by Steven J. L... more An Introduction to the Event-Related Potential Technique (Cognitive Neuroscience), by Steven J. Luck. 2006. Cambridge, MA: Bradford/MIT Press, 376 pp., $40.00 (PB) The dramatic increased interest in event-related potential (ERP) techniques in recent years has been very gratifying in light of concerns a few years ago that this approach to studying brain function would be eclipsed by developments in other areas of functional neuroimaging (e.g., PET, fMRI) that have better spatial resolution. Instead, there has been increasing recognition that the study of event-related electrical potentials and neuromagnetic responses remains a critical complements to “hemodynamic” approaches, in part because they provide a millisecond-by-millisecond record of neural information processing that occurs between presentation of a discrete stimulus and the production of the motor response. This exquisite temporal resolution cannot be matched by techniques such as PET or fMRI. Moreover, ERPs provide a more direct index of neural activity related to stimulus events than procedures dependent on the coupling of brain activity with cerebral blood flow. The instrumentation is comparatively low cost for setup and maintenance and potentially portable so studies can be obtained in a variety of settings. In this context, this engagingly written Introduction to the Event-Related Potential Technique by Steven J. Luck represents an important and long overdue entry-level book to provide practical and concise information about ERP theory and methods.
Journal of the American Academy of Child and Adolescent Psychiatry, Apr 1, 1996
Archives of neurology, Aug 1, 1989
Steady-state auditory evoked responses to frequency-modulated tones were obtained from normal chi... more Steady-state auditory evoked responses to frequency-modulated tones were obtained from normal children and two groups of children with developmental language disorders (developmental dysphasia). Children with predominantly expressive language impairment produced responses not different from normal children, while children with primary receptive language impairment produced responses that were markedly diminished, even absent. This occurred in recordings from either cerebral hemisphere and at mean frequency-modulation depths ranging from +/- 20 to +/- 100 Hz. Pathophysiology of auditory mechanisms concerned with frequency-modulation analysis are particularly associated with receptive developmental language impairment and may underlie associated difficulties in speech perception.
Neuropsychology Review, Aug 13, 2011
Autistic Disorder (AD) is a phenotypically heterogeneous condition characterized by impairments i... more Autistic Disorder (AD) is a phenotypically heterogeneous condition characterized by impairments in social interaction, communication, and the presence of repetitive behavior and restricted interests. It is a model syndrome to investigate neural interaction and integration at the nexus of language and social cognition. This paper considers the problems of language acquisition in AD from an evolutionary and ontogenetic context. Following a review of normal language development during the formative years of brain development, we examine what is known about infant linguistic and nonlinguistic precursors of language acquisition in AD and examine how anomalies of several processes relate to language abnormalities manifest by the early elementary school years. Population heterogeneity and practical limitations inherent to the study of children currently limit a comprehensive understanding of the significance of specific neurological abnormalities in relation to observed deficits. However, convergent evidence implicates anomalies of a widely distributed neural network, involving superior temporal sulcus, superior temporal gyrus, supramarginal gyrus, insula, inferior frontal gyrus, hippocampus, amygdala and cerebellum. These anomalies reflect the cumulative effects of genetic, epigenetic and environmental influences. Neuropsychological studies of language in AD provide an important means to define the phenotypic variation resulting from alterations in neural architecture. By mapping broad relationships between key symptoms, neuropsychological impairment and neural substrate, information derived from these studies enable a level of analysis that bridges the gap between the genome and the syndrome. Further study of children during the critical first 2 years of life using behavioral, electrophysiological, and functional neuroimaging methods is essential.
Journal of The International Neuropsychological Society, Jul 1, 2005
Pure word deafness (PWD) is a rare neurological syndrome characterized by severe difficulties in ... more Pure word deafness (PWD) is a rare neurological syndrome characterized by severe difficulties in understanding and reproducing spoken language, with sparing of written language comprehension and speech production. The pathognomonic disturbance of auditory comprehension appears to be associated with a breakdown in processes involved in mapping auditory input to lexical representations of words, but the functional locus of this disturbance and the localization of the responsible lesion have long been disputed. We report here on a woman with PWD resulting from a circumscribed unilateral infarct involving the left superior temporal lobe who demonstrated significant problems processing transitional spectrotemporal cues in both speech and nonspeech sounds. On speech discrimination tasks, she exhibited poor differentiation of stop consonant-vowel syllables distinguished by voicing onset and brief formant frequency transitions. Isolated formant transitions could be reliably discriminated only at very long durations (> 200 ms). By contrast, click fusion threshold, which depends on millisecond-level resolution of brief auditory events, was normal. These results suggest that the problems with speech analysis in this case were not secondary to general constraints on auditory temporal resolution. Rather, they point to a disturbance of left hemisphere auditory mechanisms that preferentially analyze rapid spectrotemporal variations in frequency. The findings have important implications for our conceptualization of PWD and its subtypes.
Journal of Developmental and Behavioral Pediatrics, Feb 1, 1994
Cornelia de Lange Syndrome (DLS) is a dysmorphogenic disorder typically associated with severe me... more Cornelia de Lange Syndrome (DLS) is a dysmorphogenic disorder typically associated with severe mental retardation. This report describes a rare case with normal-range verbal intelligence and specific cognitive deficits suggestive of a developmental visuospatial disorder. This was apparent in selective deficits in the ability to integrate visual percepts, copy spatial configurations, and manipulate representations of objects in space. Visual memory and psychomotor skills were also impaired. These deficits occurred within the context of normal language abilities and language-related academic achievement. The observed pattern of neuropsychologic impairment, in addition to aspects of socioemotional development, was similar to that seen in children with developmental right-hemisphere dysfunction. These findings suggest that the factors underlying DLS can be associated with fairly specific aberrations of cortical functioning.
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Papers by Gerry A Stefanatos, D.Phil.