The Distribution of Attention Across Auditory Input Channels: An Assessment Using the Human Evoked Potential

In order to determine the extent to which distraction disrupts performance when attention is divided, the distribution of attention across five auditory input channels was assessed using the N1 component of the human auditory evoked potential. In addition, the possibility that methylphenidate (Ritalin) affects the distribution of attention across input channels was tested. Sixteen subjects performed a tone discrimination task under conditions of focused attention and divided attention, both with and without the presence of stimuli interposed between the points to be attended. The subjects performed in two sessions during which they received either methylphenidate (10 mg) or a placebo in a double-blind design. The results showed that the interposed stimuli were receiving some attention resulting in a disruption of performance. Methylphenidate did not affect the distribution of attention as reflected in the N1 wave. The data are interpreted as showing that: 1) distraction plays a major role in producing performance deficits observed with divided attention; and 2) methylphenidate does not appreciably affect the distribution of attention across input channels.     

Distributed cortical networks for focused auditory attention and distraction

We used behavioral measures and functional magnetic resonance imaging (fMRI) to study the effects of parametrically varied task-irrelevant pitch changes in attended sounds on loudness-discrimination performance and brain activity in cortical surface maps. Ten subjects discriminated tone loudness in sequences that also included infrequent task-irrelevant pitch changes. Consistent with results of previous studies, the task-irrelevant pitch changes impaired performance in the loudness discrimination task. Auditory stimulation, attention-enhanced processing of sounds and motor responding during the loudness discrimination task activated supratemporal (auditory cortex) and inferior parietal areas bilaterally and left-hemisphere (contralateral to the hand used for responding) motor areas. Large pitch changes were associated with right hemisphere supratemporal activations as well as widespread bilateral activations in the frontal lobe and along the intraparietal sulcus. Loudness discrimination and distracting pitch changes activated common areas in the right supratemporal gyrus, left medial frontal cortex, left precentral gyrus, and left inferior parietal cortex.     

Ilizarov bone transport after massive tibial trauma: Case report

IntroductionThis is a case report of extreme lengthening of the tibia of about 14.5 cm using bone transport technique following road traffic accident trauma to the lower limbs. The management of the subsequent massive skeletal defects was challenging to orthopedic surgeons. Based on reported cases, the highest tibial lengthening was 22 cm using bifocal transport, while the highest unifocal tibial lengthening reached 14.5 cm.Case presentationA 20-year-old male driver was brought to the emergency department after a road traffic accident. The patient had a right Gustilo IIIA segmental open tibia fracture with bone loss and other severe injuries. The tibial defect was 14.5 cm and the patient was then admitted for Ilizarov application six months after the accident. Although this case was particularly complicated, full limb length was restored.DiscussionThe management of this case was directed to correct the deformities and achieve equal length of both limbs to restore the normal function. Several new techniques have been developed recently to fill large bone defects. Limb lengthening using bone transport technique by application of Ilizarov ring fixator has been suggested as the leading option in filling massive bone gaps.ConclusionThe use of bone transport technique using Ilizarov external rings has proved to be a minimally invasive and reliable method in managing massive bone defects. Accurate application of the Ilizarov frame and proper transport of the middle segment are important factors alleviating the risk for deviation of the transported segment. However, due to the need for regular follow-ups and monitoring, it demands high compliance from the patient to achieve optimal results.     

Association of deferring a quit attempt with smoking cessation success: A secondary analysis

Several smoking cessation treatments ask smokers to wait to quit to obtain treatment. We report a secondary analysis of whether a later quit attempt is associated with less success. In a placebo-controlled trial of varenicline that allowed smokers to set their quit date within 5 weeks after starting medication, 24% had their first quit attempt during week 1, and 27%, 19%, 18% and 12% in subsequent weeks. Continuous abstinence between 9 and 24 weeks declined over time; that is, from 36% to 37%, 35%, 29%, and 18% across the 5 weeks (p < 0.001). The only statistically significant difference was between the last week and prior weeks. Whether a later quit attempt actually causes less success or is a marker for other variables (e.g., low motivation) is unclear.     

Osteodistraction of mandibles with a small bone defect at the planned osteotomy site: A histological pilot study in dogs

AimTo develop a treatment plan for cases in which a bone defect is located on the osteotomy line of mandibular osteodistraction (DO).Subjects and methodsBilateral DO was performed in 17 Mongrel dogs. Prior to surgery, the 34 hemi-mandibles were randomly allocated to three groups: C (n = 10; a standard DO was performed), D − G (n = 12; a bone defect was created on the DO osteotomy line), and D + G (n = 12; the bone defect on the osteotomy line was grafted). After one week of latency, 8 days of distraction, and 4 weeks of consolidation the animals were sacrificed, and the newly formed bone were examined.ResultsIn group C, two zones of immature trabecular bone originating from host bone margins were separated by a central fibrous zone. In group D + G uniform new bone formation of the entire distraction gap was observed. In group D − G the distraction gap was mainly filled with fibrous tissue. The values for the newly formed bone volume and trabecular thickness were not significantly different between groups D + G and C, but were higher than values in group D − G (p < 0.05).ConclusionWhen a mandibular defect is located at the site of distraction osteotomy, DO can be performed simultaneous with bone grafting of the defect.     

Distraction and target selection in the brain: An fMRI study

To attend successfully, a specification of what is currently relevant is necessary, but not sufficient. Irrelevant stimuli that are also present in the environment must be recognized as such and filtered out at the same time. Using functional magnetic resonance imaging, we showed that posterior brain regions in parietal, occipital and temporal cortex are recruited in order to ignore distracting visual stimuli, while the specification and selection of relevant stimuli is associated with differential activity in frontal cortex and hippocampal areas instead. The results thus suggest that the selection of relevant objects can be anatomically dissociated from the handling of competing irrelevant objects. The dissociation between the increased involvement of parietal and occipital cortex in handling distraction on one hand, and that of frontal cortex in target specification on the other provides neurophysiological support for models of attention that make this functional distinction.     

渐进缺血后适应对经皮冠状动脉介入术患者心脏的保护作用

目的：探讨直接经皮冠状动脉（冠脉）介入术（PPCI）中渐进缺血后适应（IP）再灌注对ST段抬高型急性心肌梗死（STEAMI）再灌注损伤的保护作用。方法选择2011年2月至2014年8月在江苏昆山市第一人民医院、江苏大学附属昆山医院心内科住院行PPCI的STEAMI患者102例,将患者按随机数字表法分为IP组32例、渐进IP组30例、常规再灌注组40例。IP组开通梗死相关血管后,通过预扩张球囊充盈/撤压时间为1 min/1 min,循环3次,然后予以持续再灌注;渐进IP组实施IP的时间呈渐进变化,即在3次球囊充盈/撤压时间分别为1 min/1 min、30 s/30 s、15 s/15 s;常规再灌注组闭塞血管开通后持续恢复冠脉供血。比较3组相关导联再灌注心律失常发生率、ST段回落率、校正心肌梗死溶栓治疗（TIMI）帧数（CTFC）、肌酸激酶同工酶（CK-MB）峰值、左室射血分数（LVEF）的变化,并随访不良事件的发生情况。结果3组基线资料均衡,有可比性。渐进IP组频发室性期前收缩（室早）发生率明显低于常规再灌注组〔30.0%（9/30）比55.0%（22/40）, P＜0.05〕,IP组〔34.4%（11/32）〕室早发生率虽低于常规再灌注组,但差异无统计学意义（P＞0.05）。IP组和渐进IP组室性心动过速（室速）发生率明显低于常规再灌注组〔15.6%（5/32）、13.3%（4/30）比40.0%（16/40）,均P＜0.05〕。IP组、渐进IP组心室纤颤、心动过缓、窦性停搏的发生率均低于常规再灌注组,但差异均无统计学意义（均P＞0.05）。IP组、渐进IP组ST段回落率、CTFC、CK-MB峰值均明显低于的常规再灌注组〔ST段回落：（56.7±18.3）%、（57.3±21.5）%比（44.6±21.6）%;CTFC（帧）：25.47±5.37、24.46±6.41比31.62±7.56;CK-MB峰值（U/L）：126.3±78.5、121.6±82.5比147.4±72.5;均P＜0.05〕,且以渐进IP组作用更优。IP组、渐进IP组LVEF水平均高于常规再灌注组（0.507±0.042、0.511±0.062比0.497±0.062）,但差异无统计学意义（均P＞0.05）。常规再灌注组因反复室颤不能纠正死亡1例,无复流死亡1例。3组均各有1例患者术后4周内死亡,其中常规再灌注组1例为难治性心衰,IP组的2例均考虑为亚急性支架内血栓形成。各组均无严重出血事件的发生。结论渐进IP能更显著减轻STEAMI患者PPCI术中的心肌再灌注损伤。