Search results for "Ceph"
showing 10 items of 2036 documents
Processing of auditory stimuli during tonic and phasic periods of REM sleep as revealed by event-related brain potentials
1996
The brain has been reported to be more preoccupied with dreams during phasic than during tonic REM sleep. Whether these periods also differ in terms of the processing of external stimuli was examined. Event-related brain potentials (ERPs) to a frequent standard tone of 1000 Hz (P = 97%) and infrequent deviant tones of 1100 and 2000 Hz (P = 1.5% for each) were recorded (n = 13) during wakefulness and nocturnal sleep. An ERP wave (called REM-P3) resembling a waking P3 wave was larger for the 2000 Hz deviant during tonic than during phasic REM sleep. Also the P210 wave was larger during tonic than during phasic REM sleep. A reliable mismatch negativity component appeared only in wakefulness. I…
Speech- and sound-segmentation in dyslexia: evidence for a multiple-level cortical impairment
2006
Developmental dyslexia involves deficits in the visual and auditory domains, but is primarily characterized by an inability to translate the written linguistic code to the sound structure. Recent research has shown that auditory dysfunctions in dyslexia might originate from impairments in early pre-attentive processes, which affect behavioral discrimination. Previous studies have shown that whereas dyslexic individuals are deficient in discriminating sound distinctions involving consonants or simple pitch changes, discrimination of other sound aspects, such as tone duration, is intact. We hypothesized that such contrasts that can be discriminated by dyslexic individuals when heard in isolat…
Learning-induced neural plasticity of speech processing before birth
2013
Learning, the foundation of adaptive and intelligent behavior, is based on plastic changes in neural assemblies, reflected by the modulation of electric brain responses. In infancy, auditory learning implicates the formation and strengthening of neural long-term memory traces, improving discrimination skills, in particular those forming the prerequisites for speech perception and understanding. Although previous behavioral observations show that newborns react differentially to unfamiliar sounds vs. familiar sound material that they were exposed to as fetuses, the neural basis of fetal learning has not thus far been investigated. Here we demonstrate direct neural correlates of human fetal l…
Wertheim’s hypothesis on ‘highway hypnosis’: empirical evidence from a study on motorway and conventional road driving
2003
This paper aims to study the phenomenon known as 'highway hypnosis' or 'driving without attention mode', which has been defined as a state showing sleepiness signs and attention slip resulting from driving a motor vehicle for a long period in a highly predictable environment with low event occurrence, this being the case with motorways and very familiar roads [Highway hypnosis: a theoretical analysis. In: Gale, A.G., Brown, I.D., Haslegrave, C.M., Moorhead, I., Taylor, S. (Eds.), Vision in Vehicles-III. Elsevier, North-Holland, pp. 467-472]. According to Wertheim's hypothesis on 'highway hypnosis', long-term driving on motorways and conventional roads, e.g. main roads, secondary roads--impl…
Driving on the motorway: the effect of alternating speed on driver's activation level and mental effort
2002
When most of the driving tasks are performed automatically, a driver's level of alertness may decline, as has been pointed out in the study of the phenomenon called 'highway hypnosis'. One possible countermeasure is to periodically vary the speed (Wertheim 1978), but the authors have not found any studies that directly assess the effectiveness of this countermeasure. The objective of our study has been to provide empirical evidence regarding the effects of this strategy on the level of driver activation on a motorway route in real traffic. In the present study activation level as indexed by a relative measure based on slow EEG activity tended to be significantly higher when speed was modifi…
Learning by heart : cardiac cycle reveals an effective time window for learning
2018
Cardiac cycle phase is known to modulate processing of simple sensory information. This effect of the heartbeat on brain function is likely exerted via baroreceptors, the neurons sensitive for changes in blood pressure. From baroreceptors, the signal is conveyed all the way to the forebrain and the medial prefrontal cortex. In the two experiments reported, we examined whether learning, as a more complex form of cognition, can be modulated by the cardiac cycle phase. Human participants ( experiment 1) and rabbits ( experiment 2) were trained in trace eyeblink conditioning while neural activity was recorded. The conditioned stimulus was presented contingently with either the systolic or dias…
Contrast-enhanced transcranial Doppler ultrasonography in the diagnosis of brain death
2013
The diagnosis of brain death (BD) is based on clinical criteria including deep coma, brain stem areflexia and apnoea. Depending on different local guidelines, confirmatory technical tests are sometimes mandatory.1 Since the 1990s, transcranial Doppler sonography (TCD) has found its place in these circumstances and fulfils most of the criteria of an ‘ideal test’ in confirming BD. To confirm intracranial circulatory arrest (CA) with Doppler sonography, typical flow patterns must be recorded in bilateral intracranial and extracranial brain-supplying arteries.2 A completely absent intracranial flow signal is not a reliable sign to determine CA because this can be due to transmission problems. I…
Functional anatomy of motor recovery after early brain damage
2004
Functional magnetic resonance imaging and transcranial magnetic stimulation were used to examine a 34 year-old right-handed patient, who, at the age of 6 years, had experienced sudden right hemiplegia, seizures, and stupor during a bout of measles encephalitis, followed by incomplete distal right motor recovery. Morphological MRI showed massive unilateral enlargement of the left ventricle, associated with extreme thinning of the white and gray matter, with partial preservation of the pyramidal tract. Functional MRI and transcranial magnetic stimulation revealed reorganization of the motor cortices, and integrity of the corticospinal pathway, respectively. Our findings indicate that complete…
Both rare and de novo copy number variants are prevalent in agenesis of the corpus callosum but not in cerebellar hypoplasia or polymicrogyria.
2013
Agenesis of the corpus callosum (ACC), cerebellar hypoplasia (CBLH), and polymicrogyria (PMG) are severe congenital brain malformations with largely undiscovered causes. We conducted a large-scale chromosomal copy number variation (CNV) discovery effort in 255 ACC, 220 CBLH, and 147 PMG patients, and 2,349 controls. Compared to controls, significantly more ACC, but unexpectedly not CBLH or PMG patients, had rare genic CNVs over one megabase (p = 1.48×10−3; odds ratio [OR] = 3.19; 95% confidence interval [CI] = 1.89–5.39). Rare genic CNVs were those that impacted at least one gene in less than 1% of the combined population of patients and controls. Compared to controls, significantly more AC…
Orthodontic camouflage versus orthognathic surgery for class III deformity: comparative cephalometric analysis
2017
The objective of this study was to compare different cephalometric variables in adult patients with class III malocclusions before and after treatment, in order to determine which variables are indicative of orthodontic camouflage or orthognathic surgery. The cases of 156 adult patients were assessed: 77 treated with orthodontic camouflage and 79 treated with orthodontics and orthognathic surgery. The following cephalometric variables were measured on pre-treatment (T1) and post-treatment (T2) lateral cephalograms: sella-nasion-A-point (SNA), sella-nasion-B-point (SNB), and A-point-nasion-B-point (ANB) angles, Wits appraisal, facial axis angle, mandibular plane angle, upper and lower inciso…