268 research outputs found
Vision After Early-Onset Lesions of the Occipital Cortex: I. Neuropsychological and Psychophysical Studies
We analyzed the visual functions of two
patients (MS, FJ) with bilateral lesion of the
primary visual cortex, which occurred at gestational
age 33 wk in MS and at postnatal month 7
in FJ. In both patients basic visual functions—
visual acuity, contrast sensitivity, color, form,
motion perception—are similarly preserved or
modestly impaired. Functions requiring higher
visual processing, particularly figure-ground
segregation based on textural cues, are severely
impaired. In MS, studied longitudinally, the
deficits attenuated between the ages of 4.5 and 8
y, suggesting that the developing visual system
can display a considerable degree of adaptive
plasticity several years after the occurrence of a
lesion. In FJ (age 18:9 to 20:6 y), who is more
impaired, the recovery, if any, was less
Vision After Early-Onset Lesions of the Occipital Cortex: II. Physiological Studies
In one of two patients (MS and FJ) with
bilateral, early-onset lesion of the primary
visual cortex, Kiper et al. (2002) observed
a considerable degree of functional recovery. To
clarify the physiological mechanisms involved
in the recovery, we used fMRI and quantitative
EEG to study both patients. The fMRI
investigations indicated that in both patients,
isolated islands of the primary visual cortex are
functioning, in the right hemisphere in MS and
in the left in FJ. The functional recovery
observed in MS roughly correlated with the
functional maturation of interhemispheric
connections and might reflect the role of corticocortical connectivity in visual perception. The
functionality of interhemispheric connections
was assessed by analyzing the changes in
occipital inter-hemispheric coherence of EEG
signals (ICoh) evoked by moving gratings. In
the patient MS, this ICoh response was present
at 7:11 y and was more mature at 9:2 y. In the
more visually mpaired patient, FJ, a consistent
increase in ICoh to visual stimuli could not be
obtained, possibly because of the later occurrence
of the lesion
Patterns of language and auditory dysfunction in 6-year-old children with epilepsy
In a previous study we reported difficulty with expressive language and visuoperceptual ability in preschool children with epilepsy and otherwise normal development. The present study analysed speech and language dysfunction for each individual in relation to epilepsy variables, ear preference, and intelligence in these children and described their auditory function. Twenty 6-year-old children with epilepsy (14 females, 6 males; mean age 6:5 y, range 6 y–6 y 11 mo) and 30 reference children without epilepsy (18 females, 12 males; mean age 6:5 y, range 6 y–6 y 11 mo) were assessed for language and auditory ability. Low scores for the children with epilepsy were analysed with respect to speech-language domains, type of epilepsy, site of epileptiform activity, intelligence, and language laterality. Auditory attention, perception, discrimination, and ear preference were measured with a dichotic listening test, and group comparisons were performed. Children with left-sided partial epilepsy had extensive language dysfunction. Most children with partial epilepsy had phonological dysfunction. Language dysfunction was also found in children with generalized and unclassified epilepsies. The children with epilepsy performed significantly worse than the reference children in auditory attention, perception of vowels and discrimination of consonants for the right ear and had more left ear advantage for vowels, indicating undeveloped language laterality
Representationalism and the Intentionality of Moods
It seems hard to comprehend how, during mood experience, the ‘inner’ meets the ‘outer’. The objective of this paper is to show that a currently popular attempt at providing a neat solution to that problem fails. The attempt comes under the heading of representationalism, according to which the phenomenal aspects of mood are exhausted by its representational content. I examine three accounts of intentionality developed within the representationalist camp, and I show that they incur phenomenological and metaphysical costs. © 2017, Springer Science+Business Media Dordrecht
Medical conditions in autism spectrum disorders
Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development
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