Foveal vision predictively sensitizes to defining features of eye movement targets

Despite the fovea's singular importance for active human vision, the impact of large eye movements on foveal processing remains elusive. Building on findings from passive fixation tasks, we hypothesized that during the preparation of rapid eye movements (saccades), foveal processing anticipates soon-to-be fixated visual features. Using a dynamic large-field noise paradigm, we indeed demonstrate that sensitivity for defining features of a saccade target is enhanced in the pre-saccadic center of gaze. Enhancement manifested in higher Hit Rates for foveal probes with target-congruent orientation, and a sensitization to incidental, target-like orientation information in foveally presented noise. Enhancement was spatially confined to the center of gaze and its immediate vicinity. We suggest a crucial contribution of foveal processing to trans-saccadic visual continuity which has previously been overlooked: Foveal processing of saccade targets commences before the movement is executed and thereby enables a seamless transition once the center of gaze reaches the target.

Fixational Eye Movements Depend on Task and Target

Human fixational eye movements are so small and precise that they require high-speed, accurate tools to fully reveal their properties and functional roles. Where the fixated image lands on the retina and how it moves for different levels of visually demanding tasks is the subject of the current study. An Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) was used to image, track and present Maltese cross, disk, concentric circles, Vernier and tumbling-E letter fixation targets to healthy subjects. During these different passive (static) or active (discriminating) fixation tasks under natural eye motion, the landing position of the target on the retina was tracked in space and time over the retinal image directly. We computed both the eye motion and the exact trajectory of the fixated target's motion over the retina. We confirmed that compared to passive fixation, active tasks elicited a partial inhibition of microsaccades, leading to longer drifts periods compensated by larger corrective saccades. Consequently the fixation stability during active tasks was larger overall than during passive tasks. The preferred retinal locus of fixation was the same for each task and did not coincide with the location of the peak cone density.

Fast responses to images of animate and inanimate objects in the nonhuman primate amygdala

Visual information reaches the amygdala through the various stages of the ventral visual stream. There is, however, evidence that a fast subcortical pathway for the processing of emotional visual input exists. To explore the presence of this pathway in primates, we recorded local field potentials in the amygdala of four rhesus monkeys during a passive fixation task showing images of ten object categories. Additionally, in one of the monkeys we also obtained multi-unit spiking activity during the same task. We observed remarkably fast medium and high gamma responses in the amygdala of the four monkeys. These responses were selective for the different stimulus categories, showed within-category selectivity, and peaked as early as 60 ms after stimulus onset. Multi-unit responses in the amygdala were lagging the gamma responses by about 40 ms. Thus, these observations add further evidence that selective visual information reaches the amygdala of nonhuman primates through a very fast route.

Functional ultrasound imaging of deep visual cortex in awake nonhuman primates

Deep regions of the brain are not easily accessible to investigation at the mesoscale level in awake animals or humans. We have recently developed a functional ultrasound (fUS) technique that enables imaging hemodynamic responses to visual tasks. Using fUS imaging on two awake nonhuman primates performing a passive fixation task, we constructed retinotopic maps at depth in the visual cortex (V1, V2, and V3) in the calcarine and lunate sulci. The maps could be acquired in a single-hour session with relatively few presentations of the stimuli. The spatial resolution of the technology is illustrated by mapping patterns similar to ocular dominance (OD) columns within superficial and deep layers of the primary visual cortex. These acquisitions using fUS suggested that OD selectivity is mostly present in layer IV but with extensions into layers II/III and V. This imaging technology provides a new mesoscale approach to the mapping of brain activity at high spatiotemporal resolution in awake subjects within the whole depth of the cortex.

Results of the Patient-Related Outcomes of Mechanical lead Extraction Techniques (PROMET) study: a multicentre retrospective study on advanced mechanical lead extraction techniques

Aims Several large studies have documented the outcome of transvenous lead extraction (TLE), focusing on laser and mechanical methods. To date there has been no large series addressing the results obtained with rotational lead extraction tools. This retrospective multicentre study was designed to investigate the outcomes of mechanical and rotational techniques. Methods and results Data were collected on a total of 2205 patients (age 66.0 ± 15.7 years) with 3849 leads targeted for extraction in six European lead extraction centres. The commonest indication was infection (46%). The targeted leads included 2879 pacemaker leads (74.8%), 949 implantable cardioverter-defibrillator leads (24.6%), and 21 leads for which details were unknown; 46.6% of leads were passive fixation leads. The median lead dwell time was 74 months [interquartile range (IQR) 41–112]. Clinical success was obtained in 97.0% of procedures, and complete extraction was achieved for 96.5% of leads. Major complications occurred in 22/2205 procedures (1%), with a peri-operative or procedure-related mortality rate of 4/2205 (0.18%). Minor complications occurred in 3.1% of procedures. A total of 1552 leads (in 992 patients) with a median dwell time of 106 months (IQR 66–145) were extracted using the Evolution rotational TLE tool. In this subgroup, complete success was obtained for 95.2% of leads with a procedural mortality rate of 0.4%. Conclusion Patient outcomes in the PROMET study compare favourably with other large TLE trials, underlining the capability of rotational TLE tools and techniques to match laser methods in efficacy and surpass them in safety.

The MB score: a new risk stratification index to predict the need for advanced tools in lead extraction procedures

Aims A validated risk stratification schema for transvenous lead extraction (TLE) could improve the management of these procedures. We aimed to derive and validate a scoring system to efficiently predict the need for advanced tools to achieve TLE success. Methods and results Between November 2013 and March 2018, 1960 leads were extracted in 973 consecutive TLE procedures in two national referral sites using a stepwise approach. A procedure was defined as advanced extraction if required the use of powered sheaths and/or snares. The study population was a posteriori 1:1 randomized in derivation and validation cohorts. In the derivation cohort, presence of more than two targeted leads (odds ratio [OR] 1.76, P = 0.049), 3-year-old (OR 3.04, P = 0.001), 5-year-old (OR 3.48, P < 0.001), 10-year-old (OR 3.58, P = 0.008) oldest lead, implantable cardioverter-defibrillator (OR 3.84, P < 0.001), and passive fixation lead (OR 1.91, P = 0.032) were selected by a stepwise procedure and constituted the MB score showing a C-statistics of 0.82. In the validation group, the MB score was significantly associated with the risk of advanced extraction (OR 2.40, 95% confidence interval 2.02-2.86, P < 0.001) and showed an increase in event rate with increasing score. A low value (threshold = 1) ensured 100% sensibility and 100% negative predictive value, while a high value (threshold = 5) allowed a specificity of 92.8% and a positive predictive value of 91.9%. Conclusion In this study, we developed and tested a simple point-based scoring system able to efficiently identify patients at low and high risk of needing advanced tools during TLE procedures.

P5681Improved electrical performance/stability of a novel active fixation coronary sinus lead compared to passive fixation leads: a multi-centre study

Background A novel active fixation coronary sinus (CS) lead, Attain Stability, has been released in a bipolar and quadripolar configuration, with the hypothesis it will improve targeted lead positioning and stability independent of vessel anatomy. Purpose To compare implant procedure parameters and electrical performance/stability of a novel active fixation lead with passive fixation CS leads. Methods This was a retrospective study involving 6 major UK cardiac centres. Patients who received active leads were compared with passive lead recipients in a 1:2 ratio. The primary outcome was total lead displacements (combined macro/micro-displacements, defined as displacements requiring repositioning procedures, or an increase in threshold≥0.5 volts or pulse width≥0.5msec, or a change in pacing polarity). Multivariate analysis was performed to establish predictors of the primary outcome, assessing fixation mechanism (active or passive), number of poles (quad or bipolar), contributing hospital and follow-up duration. Results 736 patients were included (241 with active leads, 495 with passive leads). There were no group differences in the baseline characteristics with respect to age, gender, EF, NYHA class, and co-morbidities, P>0.05 for all. The primary endpoint rate was 31% (74/241) in the active and 43% (213/495) in the passive fixation group (P=0.002). 6 patients in the active group and 14 in the passive group required CS lead repositioning procedures. The results of the multivariate analysis are presented in the Table. The use of active leads was associated with a significant reduction in lead displacements, odds ratio 0.62 (95% CI 0.43–0.9), P=0.012. There were differences in favour of passive compared with active leads in procedure duration, 120 [96–149] minutes vs 128 [105–155] minutes (P=0.011), and fluoroscopy time, 17 [11–26] minutes vs 18.5 [13–27] minutes (P=0.028). The median duration of follow up was similar (active vs passive): 31 [17–47] weeks vs 34 [16–71] weeks, (P=0.052). Odds Ratio (95% Confidence Interval) P-value Active fixation CS lead 0.62 (0.43–0.9) 0.012 Quadripolar (rather than Bipolar) lead 1.26 (0.75–2.11) 0.376 Follow-up Duration (weeks) 1.005 (1.001–1.008) 0.025 Also included in the model: contributing hospital, which was significant. Conclusion In this large, multi-centre study, active fixation Attain Stability CS leads demonstrated superior electrical performance/stability compared with passive fixation leads, with minimal increases in implant procedure and fluoroscopy times. Acknowledgement/Funding None