Laparoscopic transperitoneal left adrenalectomy (LTLA) has become the standard treatment for adrenal masses <6 cm. LTLA involves the dissection of splenic suspensory ligaments, which replicates their congenital absence or weakening, present in cases of wandering spleen (WS). WS is a rare condition in which the spleen migrates from the left upper quadrant to a more caudal location in the abdomen. A unique case of WS after LTLA was described by Corcione et al. In this prospective study, we investigated the possibility of WS as a consequence of LTLA.
A commonly observed phenomenon to elucidate distortions of perceived duration is the filled-duration illusion: a temporal interval delimited by two marker signals is perceived to be shorter than the same interval with several identical filler signals. Previous investigations have focused on regularly spaced (isochronous) fillers and the influence of their temporal structure has not been considered. We find that intervals with isochronous fillers are perceived to last longer than their anisochronous counterparts. The illusion increases with the amount of deviation from isochrony and with the number of fillers. Findings also indicate that perceived duration is specifically affected by temporal irregularities, as randomization of the fillers' sound amplitude or frequency does not cause an appreciable distortion. These results can be accounted for by both pacemaker-accumulator models and entrainment models.
Mirizzi's syndrome (MS) is a rare complication of the inveterate biliary lithiasis. Diagnostic and therapeutic standardization is still missing, especially since laparoscopic cholecystectomy has become the gold standard approach for symptomatic cholelithiasis. Our study is a retrospective analysis based on a case-series. It considered 370 cholecystectomies performed from 2006 to 2011. We selected 11 patients affected by MS (2.97%). We divided them according to Csendes' classification. Endoscopic Retrograde Cholangio-Pancreatography (ERCP) was used for biliary drainage when the patient suffered jaundice and/or cholangitis and, preoperatively, to confirm the suspicion of MS obtained through Magnetic Resonance Cholangio-Pancreatography (MRCP). We found it useful to exploit nasobiliary drainage (NBD) for intra-operative check of the biliary tree. In all 5 patients of the type 1 group MS was discovered intraoperatively and treated with Laparoscopic Sub-total Cholecystectomy (LSC). One patient suffered from biliary leakage, solved with NBD positioning. The type 2 group was made up of 2 women and 1 man. All of them were preoperatively submitted to ERCP and NBD positioning. Two underwent LSC and one was converted to laparotomy. The type 3 was represented by a 63-year-old woman suffering from recurrent cholangitis. She was submitted to MRCP, ERCP and then underwent LSC. The 2 patients affected by type 4 underwent open biliary reconstruction. In conclusion, every attempt should be made to identify MS prior to LCS since it will allow NBD insertion by ERCP. Once LCS is initiated, if MS is identified intra-operatively, we can provide the most practical surgical options.
Often multisensory information is integrated in a statistically optimal fashion where each sensory source is weighted according to its precision. This integration scheme isstatistically optimal because it theoretically results in unbiased perceptual estimates with the highest precisionpossible.There is a current lack of consensus about how the nervous system processes multiple sensory cues to elapsed time.In order to shed light upon this, we adopt a computational approach to pinpoint the integration strategy underlying duration estimationof audio/visual stimuli. One of the assumptions of our computational approach is that the multisensory signals redundantly specify the same stimulus property. Our results clearly show that despite claims to the contrary, perceived duration is the result of an optimal weighting process, similar to that adopted for estimates of space. That is, participants weight the audio and visual information to arrive at the most precise, single duration estimate possible. The work also disentangles how different integration strategies - i.e. consideringthe time of onset/offset ofsignals - might alter the final estimate. As such we provide the first concrete evidence of an optimal integration strategy in human duration estimates.
Our aim was to investigate whether migraine adolescents with pain directed inside (imploding pain--IP) and outside (exploding pain--EP) the head may have different levels of cortical excitability underlying their migraineous syndrome. Ten migraine children referring prevalent EP (mean age 14.5 ± 1.4 years, 3 girls, 7 boys), 10 patients with IP (mean age 14.1 ± 2.2 years, 4 girls, 6 boys), and 13 control subjects (mean age 13 ± 1.8 years, 6 males, 7 females) participated to the study. The recovery cycle of the somatosensory evoked potentials to electrical median nerve stimuli at interstimulus intervals of 5, 20, and 40 ms was measured. Anger expression, anxiety, and somatic concerns were investigated in migraine patients. Overall, SEP recovery cycle was shorter in migraineurs than in healthy controls. The recovery cycle of the frontal N30 SEP component was significantly shorter in IP than in EP patients. While among the EP patients those with faster N30 recovery cycle had higher Trait-Anger score, the opposite was found among the IP patients. Our results suggest that the inhibitory mechanisms within the somatosensory cortex are more impaired in IP than in EP migraine adolescents. The pathophysiological difference between IP and EP migraineurs was strengthened also by the opposite correlations between the brain excitability and the anger expression.
How humans perform duration judgments with multisensory stimuli is an ongoing debate. Here, we investigated how sub-second duration judgments are achieved by asking participants to compare the duration of a continuous sound to the duration of an empty interval in which onset and offset were marked by signals of different modalities using all combinations of visual, auditory and tactile stimuli. The pattern of perceived durations across five stimulus durations (ranging from 100ms to 900ms) follows the Vierordt Law. Furthermore, intervals with a sound as onset (audio-visual, audio-tactile) are perceived longer than intervals with a sound as offset. No modality ordering effect is found for visualtactile intervals. To infer whether a single modality-independent or multiple modality-dependent time-keeping mechanisms exist we tested whether perceived duration follows a summative or a multiplicative distortion pattern by fitting a model to all modality combinations and durations. The results confirm that perceived duration depends on sensory latency (summative distortion). Instead, we did not find evidence for multiplicative distortions. The results of the model and the behavioural data support the concept of a single time-keeping mechanism that allows for judgments of durations marked by multisensory stimuli.
Recent studies show that repeated exposure to an asynchrony between auditory and visual stimuli shifts the point of subjective simultaneity. Usually, the measurement stimuli used to assess this aftereffect are interleaved with short re-exposures to the asynchrony. In a first experiment, we show that the aftereffect declines during measurement in spite of the use of re-exposures. In a second experiment, we investigate whether the observed decline is either due to a dissipation of the aftereffect with the passage of time, or the result of using measurement stimuli with a distribution of asynchronies different from the exposure stimulus. To this end, we introduced a delay before measuring the aftereffects and we compared the magnitude of the aftereffect with and without delay. We find that the aftereffect does not dissipate during the delay but instead is stored until new sensory information in the form of measurement stimuli is presented as counterevidence (i.e., stimuli with an asynchrony that differs from the one used during exposure).
Neurophysiological studies to evaluate spatial attention in children with primary headache are lacking. Tactile spatial attention modulates the N140 somatosensory evoked potential (SEP) amplitude. The aims of the study are: (1) to investigate the effect of spatial attention on the N140 amplitude in children with migraine and tension-type headache (TTH) and in healthy children, and (2) to correlate the neurophysiological results with a neuropsychological test for spatial attention.
Handling a compliant object using a pinch grasp provides sensory information about deformation and resistive force from both index finger and thumb. In this paper, an object with rigid surfaces and composed of two compliant materials fixed on a central position is used to address how information from the two fingers is integrated into a holistic percept of compliance. Results indicate that with small differences in material compliance there is a small tendency to rely more on the information at the index finger. With larger differences in material compliance participants adopt different movement patterns with the two fingers to explore the objects. Compliance judgments depend on the relative amount of motion and force exerted-the finger that presses more contributes more to the final estimate. This tendency is consistent with the utilization of a unique force signal for the two fingers. The uneven contribution of the sensory information in the pinch leads to predictable compliance discrimination performance from the performance obtained using the fingers independently.
In the Rubber Hand Illusion, the feeling of ownership of a rubber hand displaced from a participants real occluded hand is evoked by synchronously stroking both hands with paintbrushes. A change of perceived finger location towards the rubber hand (proprioceptive drift) has been reported to correlate with this illusion. To measure the time course of proprioceptive drift during the Rubber Hand Illusion, we regularly interrupted stroking (performed by robot arms) to measure perceived finger location. Measurements were made by projecting a probe dot into the field of view (using a semi-transparent mirror) and asking participants if the dot is to the left or to the right of their invisible hand (Experiment 1) or to adjust the position of the dot to that of their invisible hand (Experiment 2). We varied both the measurement frequency (every 10 s, 40 s, 120 s) and the mode of stroking (synchronous, asynchronous, just vision). Surprisingly, with frequent measurements, proprioceptive drift occurs not only in the synchronous stroking condition but also in the two control conditions (asynchronous stroking, just vision). Proprioceptive drift in the synchronous stroking condition is never higher than in the just vision condition. Only continuous exposure to asynchronous stroking prevents proprioceptive drift and thus replicates the differences in drift reported in the literature. By contrast, complementary subjective ratings (questionnaire) show that the feeling of ownership requires synchronous stroking and is not present in the asynchronous stroking condition. Thus, subjective ratings and drift are dissociated. We conclude that different mechanisms of multisensory integration are responsible for proprioceptive drift and the feeling of ownership. Proprioceptive drift relies on visuoproprioceptive integration alone, a process that is inhibited by asynchronous stroking, the most common control condition in Rubber Hand Illusion experiments. This dissociation implies that conclusions about feelings of ownership cannot be drawn from measuring proprioceptive drift alone.
How does the brain construct a percept from sensory signals? One approach to this fundamental question is to investigate perceptual learning as induced by exposure to statistical regularities in sensory signals [1-7]. Recent studies showed that exposure to novel correlations between sensory signals can cause a signal to have new perceptual effects [2, 3]. In those studies, however, the signals were clearly visible. The automaticity of the learning was therefore difficult to determine. Here we investigate whether learning of this sort, which causes new effects on appearance, can be low level and automatic by employing a visual signal whose perceptual consequences were made invisible-a vertical disparity gradient masked by other depth cues. This approach excluded high-level influences such as attention or consciousness. Our stimulus for probing perceptual appearance was a rotating cylinder. During exposure, we introduced a new contingency between the invisible signal and the rotation direction of the cylinder. When subsequently presenting an ambiguously rotating version of the cylinder, we found that the invisible signal influenced the perceived rotation direction. This demonstrates that perception can rapidly undergo "structure learning" by automatically picking up novel contingencies between sensory signals, thus automatically recruiting signals for novel uses during the construction of a percept.
Perception is fundamentally underconstrained because different combinations of object properties can generate the same sensory information. To disambiguate sensory information into estimates of scene properties, our brains incorporate prior knowledge and additional "auxiliary" (i.e., not directly relevant to desired scene property) sensory information to constrain perceptual interpretations. For example, knowing the distance to an object helps in perceiving its size. The literature contains few demonstrations of the use of prior knowledge and auxiliary information in combined visual and haptic disambiguation and almost no examination of haptic disambiguation of vision beyond "bistable" stimuli. Previous studies have reported humans integrate multiple unambiguous sensations to perceive single, continuous object properties, like size or position. Here we test whether humans use visual and haptic information, individually and jointly, to disambiguate size from distance. We presented participants with a ball moving in depth with a changing diameter. Because no unambiguous distance information is available under monocular viewing, participants rely on prior assumptions about the balls distance to disambiguate their -size percept. Presenting auxiliary binocular and/or haptic distance information augments participants prior distance assumptions and improves their size judgment accuracy-though binocular cues were trusted more than haptic. Our results suggest both visual and haptic distance information disambiguate size perception, and we interpret these results in the context of probabilistic perceptual reasoning.
After exposure to asynchronous sound and light stimuli, perceived audio-visual synchrony changes to compensate for the asynchrony. Here we investigate to what extent this audio-visual recalibration effect transfers to visual-tactile and audio-tactile simultaneity perception in order to infer the mechanisms responsible for temporal recalibration. Results indicate that audio-visual recalibration of simultaneity can transfer to audio-tactile and visual-tactile stimuli depending on the way in which the multisensory stimuli are presented. With presentation of co-located multisensory stimuli, we found a change in the perceptual latency of the visual stimuli. Presenting auditory stimuli through headphones, on the other hand, induced a change in the perceptual latency of the auditory stimuli. We argue that the difference in transfer depends on the relative trust in the auditory and visual estimates. Interestingly, these findings were confirmed by showing that audio-visual recalibration influences simple reaction time to visual and auditory stimuli. Presenting co-located stimuli during asynchronous exposure induced a change in reaction time to visual stimuli, while with headphones the change in reaction time occurred for the auditory stimuli. These results indicate that the perceptual latency is altered with repeated exposure to asynchronous audio-visual stimuli in order to compensate (at least in part) for the presented asynchrony.
Acute respiratory failure due to thyroid compression or invasion of the tracheal lumen is a surgical emergency requiring urgent management. The aim of this paper is to describe a series of six patients treated successfully in the emergency setting with total thyroidectomy due to ingravescent dyspnoea and asphyxia, as well as review related data reported in literature.
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