50 research outputs found
Configural and featural processing in humans with congenital prosopagnosia.
Prosopagnosia describes the failure to recognize faces, a deficiency that can be
devastating in social interactions. Cases of acquired prosopagnosia have often
been described over the last century. In recent years, more and more cases of
congenital prosopagnosia (CP) have been reported. In the present study we tried
to determine possible cognitive characteristics of this impairment. We used
scrambled and blurred images of faces, houses, and sugar bowls to separate
featural processing strategies from configural processing strategies. This
served to investigate whether congenital prosopagnosia results from
process-specific deficiencies, or whether it is a face-specific impairment.
Using a delayed matching paradigm, 6 individuals with CP and 6 matched healthy
controls indicated whether an intact test stimulus was the same identity as a
previously presented scrambled or blurred cue stimulus. Analyses of
dÂŽ values indicated that congenital prosopagnosia
is a face-specific deficit, but that this shortcoming is particularly pronounced
for processing configural facial information
From upright to upside-down presentation: A spatio-temporal ERP study of the parametric effect of rotation on face and house processing
<p>Abstract</p> <p>Background</p> <p>While there is a general agreement that picture-plane inversion is more detrimental to face processing than to other seemingly complex visual objects, the origin of this effect is still largely debatable. Here, we address the question of whether face inversion reflects a quantitative or a qualitative change in processing mode by investigating the pattern of event-related potential (ERP) response changes with picture plane rotation of face and house pictures. Thorough analyses of topographical (Scalp Current Density maps, SCD) and dipole source modeling were also conducted.</p> <p>Results</p> <p>We find that whilst stimulus orientation affected in a similar fashion participants' response latencies to make face and house decisions, only the ERPs in the N170 latency range were modulated by picture plane rotation of faces. The pattern of N170 amplitude and latency enhancement to misrotated faces displayed a curvilinear shape with an almost linear increase for rotations from 0° to 90° and a dip at 112.5° up to 180° rotations. A similar discontinuity function was also described for SCD occipito-temporal and temporal current foci with no topographic distribution changes, suggesting that upright and misrotated faces activated similar brain sources. This was confirmed by dipole source analyses showing the involvement of bilateral sources in the fusiform and middle occipital gyri, the activity of which was differentially affected by face rotation.</p> <p>Conclusion</p> <p>Our N170 findings provide support for both the quantitative and qualitative accounts for face rotation effects. Although the qualitative explanation predicted the curvilinear shape of N170 modulations by face misrotations, topographical and source modeling findings suggest that the same brain regions, and thus the same mechanisms, are probably at work when processing upright and rotated faces. Taken collectively, our results indicate that the same processing mechanisms may be involved across the whole range of face orientations, but would operate in a non-linear fashion. Finally, the response tuning of the N170 to rotated faces extends previous reports and further demonstrates that face inversion affects perceptual analyses of faces, which is reflected within the time range of the N170 component.</p
Diagnosis and management of SilverâRussell syndrome: first international consensus statement
This Consensus Statement summarizes recommendations for clinical diagnosis, investigation and management of patients with SilverâRussell syndrome (SRS), an imprinting disorder that causes prenatal and postnatal growth retardation. Considerable overlap exists between the care of individuals born small for gestational age and those with SRS. However, many specific management issues exist and evidence from controlled trials remains limited. SRS is primarily a clinical diagnosis; however, molecular testing enables confirmation of the clinical diagnosis and defines the subtype. A 'normal' result from a molecular test does not exclude the diagnosis of SRS. The management of children with SRS requires an experienced, multidisciplinary approach. Specific issues include growth failure, severe feeding difficulties, gastrointestinal problems, hypoglycaemia, body asymmetry, scoliosis, motor and speech delay and psychosocial challenges. An early emphasis on adequate nutritional status is important, with awareness that rapid postnatal weight gain might lead to subsequent increased risk of metabolic disorders. The benefits of treating patients with SRS with growth hormone include improved body composition, motor development and appetite, reduced risk of hypoglycaemia and increased height. Clinicians should be aware of possible premature adrenarche, fairly early and rapid central puberty and insulin resistance. Treatment with gonadotropin-releasing hormone analogues can delay progression of central puberty and preserve adult height potential. Long-term follow up is essential to determine the natural history and optimal management in adulthood
Can exaggerated response to a GH provocative test identify patients with partial GH insensitivity syndrome?
A feature-inversion effect: can an isolated feature show behavior like the face-inversion effect?
Novel microdeletions affecting the gnas locus in pseudohypoparathyroidism: characterization of the underlying mechanisms
Context: Pseudohypoparathyroidism type Ia (PHP1A) is a rare endocrine disorder characterized by hypocalcemia, hyperphosphatemia, multiple hormonal resistance and features of Albright hereditary osteodystrophy. When the phenotype is present but not associated to hormonal resistance, it is called psedopseudohypoparathyroidism (PPHP). Both entities have been associated to GNAS haploinsufficiency, and are mostly caused by inherited inactivating mutations at GNAS gene that codes for the stimulatory alpha subunit of G protein (Gs\u3b1), though the cause remains unidentified in about 30% of patients. Objectives: The aims of our work were (i) to identify GNAS locus defects in 112 patients with clinical diagnosis of PHP1A/PPHP and no point mutations at GNAS, to improve molecular diagnostic and genetic counseling; (ii) to outline the underlying molecular mechanism(s). Methods: MS-MLPA, quantitative PCR, aCGH and long-PCR were used to search for genomic rearrangements at chromosome 20q and to identify their boundaries. We used different bioinformatic approaches to assess the involvement of the genomic architecture in the origin of the deletions. Results: We discovered seven novel genomic deletions, ranging from 106-bp to 2.6-Mb. The characterization of 5 of 7 deletion breakpoints and the definition of the putative molecular mechanisms responsible for these rearrangements revealed that Alu sequences play a major role in determining the genetic instability of the region. Conclusion: We observed that deletions at GNAS locus represent a significant cause of PPHP/PHP1A and that such defects are mostly associated with Alu-mediated recombination events. Their investigation revealed to be fundamental as, in some cases they could be misdiagnosed as imprinting defects