Trail using ants follow idiosyncratic routes in complex landscapes

A large volume of research on individually navigating ants has shown how path integration and visually guided navigation form a major part of the ant navigation toolkit for many species and are sufficient mechanisms for successful navigation. One of the behavioural markers of the interaction of these mechanisms is that experienced foragers develop idiosyncratic routes that require that individual ants have personal and unique visual memories that they use to guide habitual routes between the nest and feeding sites. The majority of ants, however, inhabit complex cluttered environments and social pheromone trails are often part of the collective recruitment, organisation and navigation of these foragers. We do not know how individual navigation interacts with collective behaviour along shared trails in complex natural environments. We thus asked here if wood ants that forage through densely cluttered woodlands where they travel along shared trails repeatedly follow the same routes or if they choose a spread of paths within the shared trail. We recorded three long homing trajectories of 20 individual wood ants in their natural woodland habitat. We found that wood ants follow idiosyncratic routes when navigating along shared trails through highly complex visual landscapes. This shows that ants rely on individual memories for habitual route guidance even in cluttered environments when chemical trail information is available. We argue that visual cues are likely to be the dominant sensory modality for the idiosyncratic routes. These experiments shed new light on how ants, or insects in general, navigate through complex multimodal environments.

Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

An ethogram identifies behavioural markers of attention to humans in European herring gulls (Larus argentatus)

Herring gulls (Larus argentatus) are one of few species thriving in anthropogenic landscapes. Their history of urbanisation and familiarity with people makes them a good target for studies of human-wildlife interactions. Previous research highlights a connection between food-stealing behaviour, success in anthropogenic areas, and increased attention towards humans, raising questions about the exact extent of a gull's knowledge of human food cues. To explore these, behavioural responses to human cues in a food-related context were investigated and presented in a systematic ethogram, which identified three distinct markers of attention. Head turns, approaches, and angular body position all differed significantly between control and food conditions, showing that attention towards humans in a food-related context was upregulated and reflected in behaviour. In food condition trials, head turns occurred more often and gulls faced more towards the experimenter with occasional approaches that were never seen in control conditions. Acoustic and behavioural human food-like cues alone seemed insufficient to elicit these responses, indicating that gulls specifically paid attention to the details of human behaviour or had specific knowledge of anthropogenic food items. These results show situation-dependent attentional modulation in gulls and provide a description of attentive behaviours that can be used in further study.

Inter-species stimulus enhancement: herring gulls (Larus argentatus) mimic human food choice during foraging

Herring gulls (Larus argentatus) are one of few species that thrive in anthropogenic landscapes, and their familiarity with people makes them an excellent target for studies of inter-species social cognition. Urban gulls pay attention to human behaviour in food-related contexts and, thus, we set out to investigate whether such cues can influence a gull's attention to and choice of potential food items in their environment. Herring gulls were given free choice of two differently coloured anthropogenic food items in the presence of a demonstrator, who was either sitting still or eating food from an item that matched one of the presented ones. We found that a demonstrator eating significantly increased the likelihood of a gull pecking one of the presented items. Furthermore, 95% of pecks were directed toward the presented food item that colour-matched the demonstrator's food item. The results showed gulls were able to use human cues for stimulus enhancement and foraging decisions. Given the relatively recent history of urbanization in herring gulls, this cross-species social information transfer could be a by-product of the cognitive flexibility inherent in kleptoparasitic species.

Scanning behaviour in ants: an interplay between random-rate processes and oscillators

At the start of a journey home or to a foraging site, ants often stop, interrupting their forward movement, turn on the spot a number of times, and fixate in different directions. These scanning bouts are thought to provide visual information for choosing a path to travel. The temporal organization of such scanning bouts has implications about the neural organisation of navigational behaviour. We examined (1) the temporal distribution of the start of such scanning bouts and (2) the dynamics of saccadic body turns and fixations that compose a scanning bout in Australian desert ants, Melophorus bagoti, as they came out of a walled channel onto open field at the start of their homeward journey. Ants were caught when they neared their nest and displaced to different locations to start their journey home again. The observed parameters were mostly similar across familiar and unfamiliar locations. The turning angles of saccadic body turning to the right or left showed some stereotypy, with a peak just under 45°. The direction of such saccades appears to be determined by a slow oscillatory process as described in other insect species. In timing, however, both the distribution of inter-scanning-bout intervals and individual fixation durations showed exponential characteristics, the signature for a random-rate or Poisson process. Neurobiologically, therefore, there must be some process that switches behaviour (starting a scanning bout or ending a fixation) with equal probability at every moment in time. We discuss how chance events in the ant brain that occasionally reach a threshold for triggering such behaviours can generate the results.

Impact of central complex lesions on innate and learnt visual navigation in ants

Wood ants are excellent navigators, using a combination of innate and learnt navigational strategies to travel between their nest and feeding sites. Visual navigation in ants has been studied extensively, however, we have little direct evidence for the underlying neural mechanisms. Here, we perform lateralized mechanical lesions in the central complex (CX) of wood ants, a midline structure known to allow an insect to keep track of the direction of sensory cues relative to its own orientation and to control movement. We lesioned two groups of ants and observed their behaviour in an arena with a large visual landmark present. The first group of ants were naïve and when intact such ants show a clear innate attraction to the conspicuous landmark. The second group of ants were trained to aim to a food location to the side of the landmark. The general heading of naïve ants towards a visual cue was not altered by the lesions, but the heading of ants trained to a landmark adjacent food position was affected. Thus, CX lesions had a specific impact on learnt visual guidance. We also observed that lateralised lesions altered the fine details of turning with lesioned ants spending less time turning to the side ipsilateral of the lesion. The results confirm the role of the CX in turn control and highlight its important role in the implementation of learnt behaviours that rely on information from other brain regions.

TNM Staging and Overall Survival in Patients with Pheochromocytoma and Sympathetic Paraganglioma

BACKGROUND

Pheochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors. Metastases develop in 15-20%. The American Joint Committee on Cancer (AJCC) established inaugural guidelines for PPGL tumor-node-metastasis (TNM) staging. The objective of this analysis is to investigate the associations between TNM staging and overall survival (OS).

METHODS

We retrospectively applied the TNM staging at the time of diagnosis of the primary tumor. The primary outcome was OS. Unadjusted survival rates were estimated by the Kaplan-Meier method. Cox proportional hazards regression models were used to evaluate the associations between OS and covariates of interest.

RESULTS

The study included 458 patients. Median OS was 18.0 (95% CI: 15.6-not reached) years. At diagnosis, 126 (27.5%) tumors were stage I, 213 (46.5%) were stage II, 47 (10.3%) were stage III, and 72 (15.7%) were stage IV. The 10-year OS probabilities were 0.844 (95% CI: 0.768-0.928) for patients with stage I tumors, 0.792 (95% CI: 0.726-0.865) for stage II, 0.595 (95% CI: 0.435-0.813) for stage III, and 0.221 (95% CI: 0.127-0.384) for stage IV. Compared with stage I, the hazard ratios (HR) for death were 1.50 (0.87-2.57) for stage II, 2.85 (1.45-5.63) for stage III, and 8.88 (5.16-15.29) for stage IV (p < 0.001). Compared with patients with no germline mutations, those with RET 634/918 had better OS (HR: 0.28, 95% CI: 0.12-0.69). Other germline mutations, including SDHB, did not exhibit worse OS than patients with metastasis and sporadic disease.

CONCLUSIONS

OS rates correlated with the recently developed AJCC TNM staging and was not worse in hereditary disease. Stage IV disease exhibited a significantly shorter OS compared with stages I-III. Future staging systems could be adjusted to better separate stages I and II.

Production of adaptive movement patterns via an insect inspired spiking neural network central pattern generator

Navigation in ever-changing environments requires effective motor behaviors. Many insects have developed adaptive movement patterns which increase their success in achieving navigational goals. A conserved brain area in the insect brain, the Lateral Accessory Lobe, is involved in generating small scale search movements which increase the efficacy of sensory sampling. When the reliability of an essential navigational stimulus is low, searching movements are initiated whereas if the stimulus reliability is high, a targeted steering response is elicited. Thus, the network mediates an adaptive switching between motor patterns. We developed Spiking Neural Network models to explore how an insect inspired architecture could generate adaptive movements in relation to changing sensory inputs. The models are able to generate a variety of adaptive movement patterns, the majority of which are of the zig-zagging kind, as seen in a variety of insects. Furthermore, these networks are robust to noise. Because a large spread of network parameters lead to the correct movement dynamics, we conclude that the investigated network architecture is inherently well-suited to generating adaptive movement patterns.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Innate visual attraction in wood ants is a hardwired behavior seen across different motivational and ecological contexts

Ants are expert navigators combining innate and learnt navigational strategies. Whereas we know that the ants' feeding state segregates visual-navigational memories in ants navigating along a learnt route, it is an open question if the motivational state also affects the ants' innate visual preferences. Wood ant foragers show an innate attraction to conspicuous visual cues. These foragers inhabit cluttered woodland habitat and feed on honeydew from aphids on trees. Hence, the attraction to 'tree-like' objects might be an ecologically relevant behavior that is tailored to the wood ants' foraging ecology. Foragers from other ant species with different foraging ecologies show very different innate attractions. We investigated here the innate visual response of wood ant foragers with different motivational states, i.e., unfed or fed, as well as males that show no foraging activity. Our results show that ants from all three groups orient toward a prominent visual cue, i.e., this intrinsic visuomotor response is not context-dependent, but a hardwired behavior seen across different motivational and ecological contexts.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s00040-022-00867-3.

A unified mechanism for innate and learned visual landmark guidance in the insect central complex

Insects can navigate efficiently in both novel and familiar environments, and this requires flexiblity in how they are guided by sensory cues. A prominent landmark, for example, can elicit strong innate behaviours (attraction or menotaxis) but can also be used, after learning, as a specific directional cue as part of a navigation memory. However, the mechanisms that allow both pathways to co-exist, interact or override each other are largely unknown. Here we propose a model for the behavioural integration of innate and learned guidance based on the neuroanatomy of the central complex (CX), adapted to control landmark guided behaviours. We consider a reward signal provided either by an innate attraction to landmarks or a long-term visual memory in the mushroom bodies (MB) that modulates the formation of a local vector memory in the CX. Using an operant strategy for a simulated agent exploring a simple world containing a single visual cue, we show how the generated short-term memory can support both innate and learned steering behaviour. In addition, we show how this architecture is consistent with the observed effects of unilateral MB lesions in ants that cause a reversion to innate behaviour. We suggest the formation of a directional memory in the CX can be interpreted as transforming rewarding (positive or negative) sensory signals into a mapping of the environment that describes the geometrical attractiveness (or repulsion). We discuss how this scheme might represent an ideal way to combine multisensory information gathered during the exploration of an environment and support optimal cue integration.

A motion compensation treadmill for untethered wood ants (Formica rufa): evidence for transfer of orientation memories from free-walking training

The natural scale of insect navigation during foraging makes it challenging to study under controlled conditions. Virtual reality and trackball setups have offered experimental control over visual environments while studying tethered insects, but potential limitations and confounds introduced by tethering motivates the development of alternative untethered solutions. In this paper, we validate the use of a motion compensator (or ‘treadmill’) to study visually driven behaviour of freely moving wood ants (Formica rufa). We show how this setup allows naturalistic walking behaviour and preserves foraging motivation over long time frames. Furthermore, we show that ants are able to transfer associative and navigational memories from classical maze and arena contexts to our treadmill. Thus, we demonstrate the possibility to study navigational behaviour over ecologically relevant durations (and virtual distances) in precisely controlled environments, bridging the gap between natural and highly controlled laboratory experiments.

Summary: We have developed and validated a motion compensating treadmill for wood ants which opens new perspectives to study insect navigation behaviour in a fully controlled manner over ecologically relevant durations.

SUN-919 Ectopic ACTH Syndrome: An Aggressive Presentation Due to Metastatic Liver Cancer of Unknown Primary

Background: Ectopic Cushing’s Syndrome is a rare but often aggressive condition caused by ACTH-hypersecretion from non-pituitary tumors. In patients with metastatic cancer, as well as those with occult tumors, the diagnosis and management can be extremely challenging. Clinical Case: A 25-year old woman recently diagnosed with poorly differentiated metastatic liver carcinoma of unknown primary was admitted for lower extremity edema and worsening fatigue for the preceding month. Since being diagnosed with liver cancer, she developed uncontrolled hypertension, persistent severe hypokalemia and facial “puffiness”. Physical exam was remarkable for moon facies and truncal obesity but no evidence of striae. An overnight 1-mg dexamethasone suppression test resulted in an elevated morning cortisol level of 93.4 mcg/dL and elevated ACTH of 299 pg/mL. A 24-hour urine cortisol was significantly elevated at 4,448 mcg/24 hours. These findings were consistent with hypercortisolism due to hypersecretion of ACTH. An MRI of the sella revealed no pituitary abnormality. A high-dose dexamethasone suppresion test (single 8 mg dose) was performed and her morning cortisol level remained elevated at 98.6 mcg/dL, consistent with ectopic ACTH secretion. She was treated for the underlying malignancy with carboplatin and paclitaxel. After a thorough discussion of therapeutic options, she was prescribed Ketoconazole with the plan to medically control the hypercortisolism potentially followed by bilateral adrenalectomy. Ketoconazole was up-titrated and Spironolactone was added resulting in significant improvement of hypokalemia and hypertension. Unfortunately, one week after discharge she was re-admitted due to worsening performance status, watery diarrhea and abdominal pain. A serum cortisol level was elevated at 124 mcg/dL and Metyrapone was added to her regimen. Unfortunately, her performance status continued to decline due to progression of cancer and uncontrolled hypercortisolism. As a result, she was deemed a poor surgical candidate for bilateral adrenalectomy. The patient’s condition rapidly deteriorated and she developed malignant ascites as well as altered mental status. In accordance with her wishes, a DNR order was placed and she passed away shortly thereafter. Conclusion: Ectopic ACTH-syndrome is the etiology of 10–20% of cases of Cushing’s syndrome. Clinical presentation is often sudden and rapidly progressive. Severe hypertension and hypokalemia are seen more commonly than in Cushing’s disease. Cases secondary to occult tumors or metastatic cancer can be particularly challenging to treat when it is not possible to eliminate the source of ACTH hypersecretion via surgical or medical treatment. In patients such as this, early bilateral adrenalectomy should be considered after starting medical therapy in order to reduce morbidity and mortality due to hypercortisolism.

A Thyroid Genetic Classifier Correctly Predicts Benign Nodules with Indeterminate Cytology: Two Independent, Multicenter, Prospective Validation Trials

Background: Although most thyroid nodules with indeterminate cytology are benign, in most of the world, surgery remains as the most frequent diagnostic approach. We have previously reported a 10-gene thyroid genetic classifier, which accurately predicts benign thyroid nodules. The assay is a prototype diagnostic kit suitable for reference laboratory testing and could potentially avoid unnecessary diagnostic surgery in patients with indeterminate thyroid cytology. Methods: Classifier performance was tested in two independent, ethnically diverse, prospective multicenter trials (TGCT-1/Chile and TGCT-2/USA). A total of 4061 fine-needle aspirations were collected from 15 institutions, of which 897 (22%) were called indeterminate. The clinical site was blind to the classifier score and the clinical laboratory blind to the pathology report. A matched surgical pathology and valid classifier score was available for 270 samples. Results: Cohorts showed significant differences, including (i) clinical site patient source (academic, 43% and 97% for TGCT-1 and -2, respectively); (ii) ethnic diversity, with a greater proportion of the Hispanic population (40% vs. 3%) for TGCT-1 and a greater proportion of African American (11% vs. 0%) and Asian (10% vs. 1%) populations for TGCT-2; and (iii) tumor size (mean of 1.7 and 2.5 cm for TGCT-1 and -2, respectively). Overall, there were no differences in the histopathological profile between cohorts. Forty-one of 155 and 45 of 115 nodules were malignant (cancer prevalence of 26% and 39% for TGCT-1 and -2, respectively). The classifier predicted 37 of 41 and 41 of 45 malignant nodules, yielding a sensitivity of 90% [95% confidence interval; CI 77-97] and 91% [95% CI 79-98] for TGCT-1 and -2, respectively. One hundred one of 114 and 61 of 70 nodules were correctly predicted as benign, yielding a specificity of 89% [95% CI 82-94] and 87% [95% CI 77-94], respectively. The negative predictive values for TGCT-1 and TGCT-2 were 96% and 94%, respectively, whereas the positive predictive values were 74% and 82%, respectively. The overall accuracy for both cohorts was 89%. Conclusions: Clinical validation of the classifier demonstrates equivalent performance in two independent and ethnically diverse cohorts, accurately predicting benign thyroid nodules that can undergo surveillance as an alternative to diagnostic surgery.

Dynamic multimodal interactions in navigating wood ants: what do path details tell us about cue integration?

Ants are expert navigators, using multimodal information to navigate successfully. Here, we present the results of systematic studies of multimodal cue use in navigating wood ants, Formica rufa Ants learnt to navigate to a feeder that was defined by an olfactory cue (O), visual cue (V) and airflow (A) presented together. When the feeder, olfactory cue and airflow were all placed at the centre of the visual cue (VOACentre), ants did not directly approach the learnt feeder when either the olfactory or visual cue was removed. This confirms that some form of cue binding has taken place. However, in a visually simpler task with the feeder located at the edge of the visual cue (VOAEdge), ants still approached the feeder directly when individual cue components were removed. Hence, cue binding is flexible and depends on the navigational context. In general, cues act additively in determining the ants' path accuracy, i.e. the use of multiple cues increased navigation performance. Moreover, across different training conditions, we saw different motor patterns in response to different sensory cues. For instance, ants had more sinuous paths with more turns when they followed an odour plume but did not have any visual cues. Having visual information together with the odour enhanced performance and therefore positively impacted on plume following. Interestingly, path characteristics of ants from the different multimodal groups (VOACentre versus VOAEdge) were different, suggesting that the observed flexibility in cue binding may be a result of ants' movement characteristics.

Connecting brain to behaviour: a role for general purpose steering circuits in insect orientation?

The lateral accessory lobes (LALs), paired structures that are homologous among all insect species, have been well studied for their role in pheromone tracking in silkmoths and phonotaxis in crickets, where their outputs have been shown to correlate with observed motor activity. Further studies have shown more generally that the LALs are crucial both for an insect's ability to steer correctly and for organising the outputs of the descending pathways towards the motor centres. In this context, we propose a framework by which the LALs may be generally involved in generating steering commands across a variety of insects and behaviours. Across different behaviours, we see that the LAL is involved in generating two kinds of steering: (1) search behaviours and (2) targeted steering driven by direct sensory information. Search behaviours are generated when the current behaviourally relevant cues are not available, and a well-described LAL subnetwork produces activity which increases sampling of the environment. We propose that, when behaviourally relevant cues are available, the LALs may integrate orientation information from several sensory modalities, thus leading to a collective output for steering driven by those cues. These steering commands are then sent to the motor centres, and an additional efference copy is sent back to the orientation-computing areas. In summary, we have taken known aspects of the neurophysiology and function of the insect LALs and generated a speculative framework that suggests how LALs might be involved in steering control for a variety of complex real-world behaviours in insects.

Extreme Hardening of Pb at High Pressure and Strain Rate

We study the high-pressure strength of Pb and Pb-4wt%Sb at the National Ignition Facility. We measure Rayleigh-Taylor growth of preformed ripples ramp compressed to ∼400  GPa peak pressure, among the highest-pressure strength measurements ever reported on any platform. We find agreement with 2D simulations using the Improved Steinberg-Guinan strength model for body-centered-cubic Pb; the Pb-4wt%Sb alloy behaves similarly within the error bars. The combination of high-rate, pressure-induced hardening and polymorphism yield an average inferred flow stress of ∼3.8  GPa at high pressure, a ∼250-fold increase, changing Pb from soft to extremely strong.

Insect Navigation: What Backward Walking Reveals about the Control of Movement

Ants often walk backwards to drag large prey to their nest. New experiments show how they can use information from retinotopically encoded views to follow visual routes even while moving backwards. The mechanisms enabling ants to decouple body orientation and the control of travel direction are likely to be shared with other, flying, insects.

Supersonic plasma turbulence in the laboratory

The properties of supersonic, compressible plasma turbulence determine the behavior of many terrestrial and astrophysical systems. In the interstellar medium and molecular clouds, compressible turbulence plays a vital role in star formation and the evolution of our galaxy. Observations of the density and velocity power spectra in the Orion B and Perseus molecular clouds show large deviations from those predicted for incompressible turbulence. Hydrodynamic simulations attribute this to the high Mach number in the interstellar medium (ISM), although the exact details of this dependence are not well understood. Here we investigate experimentally the statistical behavior of boundary-free supersonic turbulence created by the collision of two laser-driven high-velocity turbulent plasma jets. The Mach number dependence of the slopes of the density and velocity power spectra agree with astrophysical observations, and supports the notion that the turbulence transitions from being Kolmogorov-like at low Mach number to being more Burgers-like at higher Mach numbers.

Contralateral prophylactic mastectomy in young women with breast cancer: a population-based analysis of predictive factors and clinical impact

Background and Objectives

Contralateral prophylactic mastectomy (cpm) has been increasingly common among women with unilateral invasive breast cancer (ibca) even though the data that support it are limited. Using a population-based cohort, the objectives of the present study were to describe factors predictive of cpm in young women (≤35 years) with ibca and to evaluate the impact of the procedure on mortality.

Methods

All women diagnosed during 1994-2003 and treated with cpm were identified from the Ontario Cancer Registry. Logistic regression was used to identify patient and tumour factors associated with the use of cpm. Multivariate analyses were used to assess the effect of cpm on recurrence and mortality.

Results

Of 614 women identified, 81 underwent cpm (13.2%). On multivariable analysis, factors associated with cpm included negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery with re-excision. At follow-up, breast cancer-specific mortality was similar for women who did and did not undergo cpm.

Conclusions

Use of cpm in young women with ibca (compared with non-use) was not associated improved breast cancer-specific mortality. Factors found to be predictive of cpm were negative lymph node status, negative estrogen receptor status, and initial breast-conserving surgery followed by re-excision.

The interaction of path integration and terrestrial visual cues in navigating desert ants: what can we learn from path characteristics?

Ant foragers make use of multiple navigational cues to navigate through the world and the combination of innate navigational strategies and the learning of environmental information is the secret to their navigational success. We present here detailed information about the paths of Cataglyphis fortis desert ants navigating by an innate strategy, namely path integration. Firstly, we observed that the ants' walking speed decreases significantly along their homing paths, such that they slow down just before reaching the goal, and maintain a slower speed during subsequent search paths. Interestingly, this drop in walking speed is independent of absolute home-vector length and depends on the proportion of the home vector that has been completed. Secondly, we found that ants are influenced more strongly by novel or altered visual cues the further along the homing path they are. These results suggest that path integration modulates speed along the homing path in a way that might help ants search for, utilise or learn environmental information at important locations. Ants walk more slowly and sinuously when encountering novel or altered visual cues and occasionally stop and scan the world; this might indicate the re-learning of visual information.

Neural coding in the visual system of Drosophila melanogaster: How do small neural populations support visually guided behaviours?

All organisms wishing to survive and reproduce must be able to respond adaptively to a complex, changing world. Yet the computational power available is constrained by biology and evolution, favouring mechanisms that are parsimonious yet robust. Here we investigate the information carried in small populations of visually responsive neurons in Drosophila melanogaster. These so-called 'ring neurons', projecting to the ellipsoid body of the central complex, are reported to be necessary for complex visual tasks such as pattern recognition and visual navigation. Recently the receptive fields of these neurons have been mapped, allowing us to investigate how well they can support such behaviours. For instance, in a simulation of classic pattern discrimination experiments, we show that the pattern of output from the ring neurons matches observed fly behaviour. However, performance of the neurons (as with flies) is not perfect and can be easily improved with the addition of extra neurons, suggesting the neurons' receptive fields are not optimised for recognising abstract shapes, a conclusion which casts doubt on cognitive explanations of fly behaviour in pattern recognition assays. Using artificial neural networks, we then assess how easy it is to decode more general information about stimulus shape from the ring neuron population codes. We show that these neurons are well suited for encoding information about size, position and orientation, which are more relevant behavioural parameters for a fly than abstract pattern properties. This leads us to suggest that in order to understand the properties of neural systems, one must consider how perceptual circuits put information at the service of behaviour.

Vision for navigation: What can we learn from ants?

The visual systems of all animals are used to provide information that can guide behaviour. In some cases insects demonstrate particularly impressive visually-guided behaviour and then we might reasonably ask how the low-resolution vision and limited neural resources of insects are tuned to particular behavioural strategies. Such questions are of interest to both biologists and to engineers seeking to emulate insect-level performance with lightweight hardware. One behaviour that insects share with many animals is the use of learnt visual information for navigation. Desert ants, in particular, are expert visual navigators. Across their foraging life, ants can learn long idiosyncratic foraging routes. What's more, these routes are learnt quickly and the visual cues that define them can be implemented for guidance independently of other social or personal information. Here we review the style of visual navigation in solitary foraging ants and consider the physiological mechanisms that underpin it. Our perspective is to consider that robust navigation comes from the optimal interaction between behavioural strategy, visual mechanisms and neural hardware. We consider each of these in turn, highlighting the value of ant-like mechanisms in biomimetic endeavours.

Counterpropagating Radiative Shock Experiments on the Orion Laser

We present new experiments to study the formation of radiative shocks and the interaction between two counterpropagating radiative shocks. The experiments are performed at the Orion laser facility, which is used to drive shocks in xenon inside large aspect ratio gas cells. The collision between the two shocks and their respective radiative precursors, combined with the formation of inherently three-dimensional shocks, provides a novel platform particularly suited for the benchmarking of numerical codes. The dynamics of the shocks before and after the collision are investigated using point-projection x-ray backlighting while, simultaneously, the electron density in the radiative precursor was measured via optical laser interferometry. Modeling of the experiments using the 2D radiation hydrodynamic codes nym and petra shows very good agreement with the experimental results.

Hypophysitis, Panhypopituitarism, and Hypothalamitis in a Scottish Terrier Dog

A 6‐year old male neutered Scottish Terrier was referred with a 1 week history of progressive lethargy and anorexia. Neurological examination localized a lesion to the forebrain and hormonal testing showed panhypopituitarism. Magnetic resonance imaging (MRI) of the brain revealed a rounded, well‐defined, suprasellar central mass. The mass was slightly hyperintense to the cortical grey matter on T2‐weighted (T2W), hypointense on T1‐weighted (T1W) images and without T2* signal void. There was a central fusiform enhancement of the mass after contrast administration which raised the suspicion of a pituitary neoplasm. Rapid deterioration of the dog prevented further clinical investigations. Histopathologic examination revealed a lymphocytic panhypophysitis of unknown origin suspected autoimmune involving the hypothalamus (hypothalamitis). This is a unique case report of a dog presenting with inflammatory hypophysitis and hypothalamitis of suspected autoimmune origin with detailed clinical, MRI, histology and immunohistochemistry findings.

Considering Postoperative Functional Hypoaldosteronism after Unilateral Adrenalectomy

Conn's Syndrome is an uncommon condition. Patients who have undergone adrenalectomy in the early postoperative period can demonstrate biochemical hypoaldosteronism. Given the rare nature of this phenomenon we investigated its incidence and whether it translated to clinical findings. A single-institution retrospective review of all patients with biochemically proven hyperaldosteronism from 2005 to 2014 that underwent unilateral adrenalectomy. A total of 29 patients fit the inclusion criteria. Functional hypoaldosteronism had appreciated in 18/29 (62%) patients, whereas 11 patients (38%) had normal postoperative aldosterone. No significant differences between diagnostic groups were found in terms of clinical outcomes (length of stay, postoperative symptomatology, and readmissions P = 0.669, 0.154, and 0.268, respectively). Two (7%) patients required medical therapy. Biochemical evidence of functional hypoaldosteronism was identified in two-thirds of patients undergoing unilateral adrenalectomy. Although contralateral aldosterone suppression can be anticipated, the phenotypic response varied and the outcomes were similar to patients with normal aldosterone levels. Current guidelines make no formal recommendations for assessment of hypoaldosteronism after adrenalectomy, resulting in varying practice paradigms. Surgeons should consider the risk of postoperative hypoaldosteronism in these patients and counsel patients accordingly. Prospective investigations should be performed to assist in development of an outcomes-based care delivery model for these patients.

Social Life in Arid Environments: The Case Study of Cataglyphis Ants

Unlike most desert-dwelling animals, Cataglyphis ants do not attempt to escape the heat; rather, they apply their impressive heat tolerance to avoid competitors and predators. This thermally defined niche has promoted a range of adaptations both at the individual and colony levels. We have also recently discovered that within the genus Cataglyphis there are incredibly diverse social systems, modes of reproduction, and dispersal, prompting the tantalizing question of whether social diversity may also be a consequence of the harsh environment within which we find these charismatic ants. Here we review recent advances regarding the physiological, behavioral, life-history, colony, and ecological characteristics of Cataglyphis and consider perspectives on future research that will build our understanding of organic adaptive responses to desertification.

Drosophila as a Model for Diabetes and Diseases of Insulin Resistance

Despite the importance of insulin signaling pathways in human disease, initial concerns that insect physiology and sugar metabolism differ enough from humans that flies would not model human disease hampered research in this area. However, during the past 10-15 years, evidence has accumulated that flies can indeed model various aspects of diabetes and related human disorders. This cluster of diseases impact insulin and insulin signaling pathways, fields which have been discussed in many excellent review articles in recent years. In this chapter, we restrict our focus to specific examples of diabetes-related disease models in Drosophila, discussing the advantages and limitations of these models in light of physiological similarities and differences between insects and mammals. We discuss features of metabolism and sugar regulation that are shared between flies and mammals, and specific Drosophila models for Type 1 and Type 2 diabetes, Metabolic syndrome, and related abnormalities including insulin resistance and heart disease. We conclude that fly models for diabetes and related disorders enhance our ability to identify genes and discern functional interactions that can be exploited for disease intervention.

Breast cancer detection rates, and standardised detection ratios for prevalence screening in the New Zealand breast cancer screening programme

Objectives: To calculate breast cancer detection to expected incidence ratios and standardised detection ratios (SDRs) for the New Zealand breast cancer screening programme.

Method: Breast cancer registrations for 1976-1999 were obtained from the New Zealand Cancer Registry. Using these registrations, the incidence in the absence of screening was projected for 1999 and 2000. These projections, and the invasive breast cancers detected in the New Zealand programme during 1999 and 2000, were used to calculate the detection to expected incidence ratios and SDRs.

Results: In 1999, the breast cancer detection rate was 5.6 per 1000 women screened. The expected incidence among these women in the absence of screening was 2.3 per 1000, a detection to expected incidence ratio of 2.4. The SDR was 0.84 (0.76-0.94). In 2000, the breast cancer detection rate was 6.0 per 1000 women screened. The expected incidence among these women in the absence of screening was 2.4 per 1000, a detection to expected incidence ratio of 2.5. The SDR was 0.90 (0.81 - 0.99).

Conclusions: In the first two years of the national programme, detection to expected incidence ratios were less than 3.0, and the SDR results were below 1.0. It may be unrealistic to expect new screening programmes to achieve SDRs of 1.0 immediately. At a similar stage, the UK National Health Service Breast Cancer Screening Programme (NHSBSP) also reported SDRs of less than 1.0 and therefore lower than expected cancer detection rates compared with the Swedish Two-County trial. An encouraging finding was that SDRs in five of the six screening regions improved in the second year of the New Zealand screening programme.

Abstract P1-16-03: Quantitative versus semi-quantitative assessments of radiation-induced pulmonary fibrosis post adjuvant breast radiotherapy

Objective

To evaluate the quantitative versus semi-quantitative assessments of radiation induced pulmonary fibrosis (RIPF) post adjuvant breast radiotherapy (RT).

Methods

High resolution computed tomography (HRCT) assessed lung physical density changes (CTD) and physician identified HRCT visual grading scores (CTS) were analysed at the minimum of 12 months post RT at one institution. The treated side in-portal lung regions for CTD and CTS assessments were: central-axis (CA) + regions 5cm superior & inferior to CA and the corresponding mid anterolateral region respectively. Respiratory motion was accounted for by subtracting the untreated side lung density from the treated side. Mean lung densities correspond to each voxels were automatically calculated by Pinnacle software (Phillips, Eindhoven, The-Netherlands). Grading of CTS was according to the RTOG/EORTC (grade 0, 1, 2, and 3 defined as none, slight, patchy, and dense HRCT appearance respectively) and analysed by a radiologist (JL) and re-checked a radiation oncologist (PG).

Results

Total numbers of 403 patients were analysed. A substantial association was verified between CTD and CTS assessment. An increase of ∼0.01 g/ml (95% CI 0.003-0.02) in CTD with each CTS score increase of 1 was observed (Table-1a). The RIPF can be categorised quantitatively into three groups of CTS 0 vs. 1-2 vs. 3 based on the mean CTD (Table-1b).

Table-1a. Correlation between CTD and CTS method. Table-1b. Grouping of CTS based on CTD methodTable-1a. Correlation between CTD and CTS methodCTSTreated side mean CTD - LeftTreated side mean CTD - RightMean Total00.055 (119)-0.011 (136)0.020 (255)10.065 (60)0.005 (56)0.036 (116)20.083 (15)0.012 (13)0.050 (28)30.108 (4)00.108 (4)Total0.061 (198)-0.005 (205)0.028 (403)Table-1b. Grouping of CTS based on CTD methodCTSTreated side mean CTD - LeftTreated side mean CTD - RightMean Total95% Confidence interval00.055 (119)-0.011 (136)0.020 (255)0.012-0.0271-20.069 (75)0.006 (69)0.039 (144)0.029-0.04830.108 (4)00.108 (4)0.079-0.137

A cut off CTD of 0.089 g/ml exemplified the best compromise between sensitivity (100%) and specificity (88.2%) for dense HRCT appearance. However, there was no good compromise of CTD cut off for slight and patchy HRCT score possibly due to intra observer variation and the scale of the CTD measure (small increase in CTD may not be detected visually by the observer). Multivariable analysis revealed increasing age, current smoker, V20 ≥ 10% (the volume of lung that was covered by the 20Gy isodose line), central lung distance ≥ 2cm (the distance between posterior RT tangents and the chest wall), combined endocrine & chemotherapy, and treated side mean CTD to be significantly associated with development of grade ≥1 RIPF.

Conclusions

There was a good correlation between quantitative (CTD) and semi-quantitative (CTS) assessment of RIPF post adjuvant breast RT. The CTD method could be advantageous for both routine clinical practice and future clinical trials that require more detailed quantification of dense RIPF.

Citation Format: Pramana A, Browne L, Cox H, Saba A, Pham K, Trakis S, Crawford K, Hall M, Batchelor N, Lim J, Graham P. Quantitative versus semi-quantitative assessments of radiation-induced pulmonary fibrosis post adjuvant breast radiotherapy. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-16-03.

The Sensory Ecology of Ant Navigation: From Natural Environments to Neural Mechanisms

Animals moving through the world are surrounded by potential information. But the components of this rich array that they extract will depend on current behavioral requirements and the animal's own sensory apparatus. Here, we consider the types of information available to social hymenopteran insects, with a specific focus on ants. This topic has a long history and much is known about how ants and other insects use idiothetic information, sky compasses, visual cues, and odor trails. Recent research has highlighted how insects use other sensory information for navigation, such as the olfactory cues provided by the environment. These cues are harder to understand because they submit less easily to anthropomorphic analysis. Here, we take an ecological approach, considering first what information is available to insects, then how different cues might interact, and finally we discuss potential neural correlates of these behaviors.

Navigation-specific neural coding in the visual system of Drosophila

Drosophila melanogaster are a good system in which to understand the minimal requirements for widespread visually guided behaviours such as navigation, due to their small brains (adults possess only 100,000 neurons) and the availability of neurogenetic techniques which allow the identification of task-specific cell types. Recently published data describe the receptive fields for two classes of visually responsive neurons (R2 and R3/R4d ring neurons in the central complex) that are essential for visual tasks such as orientation memory for salient objects and simple pattern discriminations. What is interesting is that these cells have very large receptive fields and are very small in number, suggesting that each sub-population of cells might be a bottleneck in the processing of visual information for a specific behaviour, as each subset of cells effectively condenses information from approximately 3000 visual receptors in the eye, to fewer than 50 neurons in total. It has recently been shown how R1 ring neurons, which receive input from the same areas as the R2 and R3/R4d cells, are necessary for place learning in Drosophila. However, how R1 neurons enable place learning is unknown. By examining the information provided by different populations of hypothetical visual neurons in simulations of experimental arenas, we show that neurons with ring neuron-like receptive fields are sufficient for defining a location visually. In this way we provide a link between the type of information conveyed by ring neurons and the behaviour they support.

Insect navigation: do ants live in the now?

Visual navigation is a critical behaviour for many animals, and it has been particularly well studied in ants. Decades of ant navigation research have uncovered many ways in which efficient navigation can be implemented in small brains. For example, ants show us how visual information can drive navigation via procedural rather than map-like instructions. Two recent behavioural observations highlight interesting adaptive ways in which ants implement visual guidance. Firstly, it has been shown that the systematic nest searches of ants can be biased by recent experience of familiar scenes. Secondly, ants have been observed to show temporary periods of confusion when asked to repeat a route segment, even if that route segment is very familiar. Taken together, these results indicate that the navigational decisions of ants take into account their recent experiences as well as the currently perceived environment.