with severe and complex speech, language and communication needsThe effectiveness of semantic therapy for the word finding difficulties of children Published by: http://www.sagepublications.com can be found at: Child Language Teaching and Therapy Additional services and information for AbstractWord finding difficulties are often seen in children with language difficulties. Their problem is readily observed and has led to investigations of its nature and encouraged attempts at intervention. Semantic errors in their naming suggest that their knowledge of items is poorly developed and that therapies to strengthen it may be effective. Twelve children between 7 and 11 years of age were offered 3 hours of semantic therapy in two 15-minute sessions per week for 6 weeks. The children had severe and complex speech, language and communication needs and all were in the bottom 5% for their age on a test of word finding. Two categories of items were treated. Each category was divided into sets of items that were directly treated, and items which appeared during therapy but were not specifically targeted. Categories and sets of items were counterbalanced across children. The children were blind assessed on naming the items before and after therapy and at a maintenance assessment 6 weeks after the treatment ceased. The children improved significantly on the treated items and on untreated items from the same category but not on items from the untreated category. Improvement was maintained at the maintenance assessment. Although results were significant, only medium effect sizes were obtained. These results add to the evidence that semantic therapy can help children with word finding difficulties. In assessing their clinical significance, the severity of the children's communication problems should be taken into account.

Collective behaviours are widely assumed to confuse predators, but empirical support for a confusion effect is often lacking, and its importance must depend on the predator’s targeting mechanism. Here we show that Swainson’s Hawks Buteo swainsoni and other raptors attacking swarming Mexican Free-tailed Bats Tadarida brasiliensis steer by turning towards a fixed point in space within the swarm, rather than by using closed-loop pursuit of any one individual. Any prey with which the predator is on a collision course will appear to remain on a constant bearing, so target selection emerges naturally from the geometry of a collision. Our results show how predators can simplify the demands on their sensory system by decoupling steering from target acquisition when capturing prey from a dense swarm. We anticipate that the same tactic will be used against flocks and schools across a wide range of taxa, in which case a confusion effect is paradoxically more likely to occur in attacks on sparse groups, for which steering and target acquisition cannot be decoupled.

Bats, quoted as sleeping for up to 20h a day, are an often used example of extreme sleep duration amongst mammals. Given that duration has historically been one of the primary metrics featured in comparative studies of sleep, it is important that species specific sleep durations are well founded. Here, we re-examined the evidence for the characterisation of bats as extreme sleepers and discuss whether it provides a useful representation of the sleep behaviour of Chiroptera. Although there are a wealth of activity data to suggest that the diurnal cycle of bats is dominated by rest, estimates of sleep time generated from electrophysiological analyses suggest considerable interspecific variation, ranging from 83% to a more moderate 61% of the 24h day spent asleep. Temperature dependent changes in the duration and electroencephalographic profile of sleep suggest that bats represent a unique model for investigating the relationship between sleep and torpor. Further sources of intra-specific variation in sleep duration, including the impact of artificial laboratory environments and sleep intensity, remain unexplored. Future studies conducted in naturalistic environments, using larger sample sizes and relying on a pre-determined set of defining criteria will undoubtedly provide novel insights into sleep in bats and other species.

Growing evidence suggests that brain activity during sleep, as well as sleep regulation, are tightly linked with synaptic function and network excitability at the local and global levels. We previously reported that a mutation in synaptobrevin 2 (Vamp2) in restless (rlss) mice results in a marked increase of wakefulness and suppression of sleep, in particular REM sleep (REMS) as well as increased consolidation of sleep and wakefulness. In the current study, using finer-scale in vivo electrophysiology recordings, we report that spontaneous cortical activity in rlss mice during NREM sleep (NREMS) is characterised by an occurrence of abnormally prolonged periods of complete neuronal silence (OFF-periods), often lasting several seconds, similar to the burst suppression pattern typically seen under deep anaesthesia. Increased incidence of prolonged network OFF-periods was not specific to NREMS, but also present in REMS and wake in rlss mice. Slow wave activity (SWA) was generally increased in rlss mice, while higher frequencies including theta-frequency activity were decreased, further resulting in diminished differences between vigilance states. The relative increase in SWA after sleep deprivation was attenuated in rlss mice, suggesting either that rlss mice experience persistently elevated sleep pressure, or, alternatively, that the intrusion of sleep-like patterns of activity into awake state diminishes the accumulation of sleep drive. We propose that deficit in global synaptic neurotransmitter release leads to "state inertia", reflected in an abnormal propensity of brain networks to enter and remain in a persistent "default state" resembling coma or deep anaesthesia.

During non-rapid eye movement sleep (NREM), synchronised neuronal activity is reflected in a specific neural oscillation observed in neocortical electrophysiological signals: a low frequency component characterised by depth-positive/surface-negative potentials known as slow waves, corresponding to alternating periods of high (ON period) and low (OFF period) spiking activity. Often overlooked in favour of slow waves, there is an interest in understanding how neuronal silencing during OFF periods leads to the generation of slow waves and whether this relationship changes between cortical layers. The foremost issue in detecting population OFF periods is the absence of a formal, widely adopted definition. Here, we grouped segments of high frequency neural activity containing spikes, recorded from the neocortex, on the basis of amplitude and asked whether the population of low amplitude (LA) segments displayed the expected characteristics of OFF periods. We corroborate previous studies showing that low amplitude segments in neural activity signals are a uniquely identifiable structure with distinct characteristics from the surrounding signal spiking that identify them as OFF periods including NREM sleep predominance and association with a local field potential (LFP) slow wave. In addition, we attribute new characteristics to these segments not previously associated with OFF periods: vigilance-state-dependent duration and duration-dependent homeostatic response. This could suggest that ON/OFF periods are currently underdefined, and their appearance is less binary than previously considered, instead representing a continuum.

The experiments performed by James Simmons helped pave the way for our understanding of bat biosonar processing and “what it’s like to be a bat.” By conducting experiments with trained bats, he discovered key information on how bats use temporal and spectral cues in their echoes to perceive their environment. After spending my postdoc with Dr. Simmons in his lab, he encouraged me to venture to the field to explore the sonar behavior of bats in their natural environment. This talk will summarize my recent work exploring sensorimotor behavior of free-tailed bats when returning to their cave roost at speeds exceeding 60 km/h. By combining acoustic recordings with multiple-camera recordings, we reconstructed the 3D path of bats in flight both during and in-between pulse emission. From these data we examined how acoustic behavior changed depending on altitude and velocity, and whether changes in flight trajectory or kinematics coincided with the reception of echoes. Our results demonstrate that when echolocating at fast flight speeds, bats use a predictable, open-loop sensing strategy to navigate their environment. This may be advantageous for bats flying at fast speeds and experiencing high g forces, as the physiological consequences of closed-loop sensing may be too demanding.

Brazilian free-tailed bats form large maternal colonies numbering in the millions across the American Southwest. Each night, the bats emerge from their roost to travel to foraging locations. During this emergence, individuals fly together in a dense, linear stream and exhibit collective group behavior. Upon morning return to the roost, the flight behavior of bats change and individuals fly in unpredictable paths, with little to no apparent collective group behavior, creating a swarm. To understand the different sensory challenges each of these flight scenarios pose to bats, we recorded the soundscapes of bats in streams and swarms using four different recording platforms: (1) stationary, ground-based directional and omnidirectional microphones, (2) a zip-line microphone that maneuvered through the bat stream and swarm and was monitored by video, (3) a microphone and thermal camera on a quadcopter that recorded bat flight behavior and signals at high altitudes during swarm re-entry, and (4) a trained hawk that flew through the bat stream while carrying a microphone unit and monitored with unique video. We report on the characteristics and variability of soundscapes for bat swarms, including different noise profiles the bats experience during streaming and swarming and the adaptive time-frequency signatures and flight behavior of individuals during group flight.

Background During non-rapid eye movement sleep (NREM), alternating periods of synchronised high (ON period) and low (OFF period) neuronal activity are associated with high amplitude delta band (0.5–4 Hz) oscillations in neocortical electrophysiological signals termed slow waves. As this oscillation is dependent crucially on hyperpolarisation of cortical cells, there is an interest in understanding how neuronal silencing during OFF periods leads to the generation of slow waves and whether this relationship changes between cortical layers. A formal, widely adopted definition of OFF periods is absent, complicating their detection. Here, we grouped segments of high frequency neural activity containing spikes, recorded as multiunit activity from the neocortex of freely behaving mice, on the basis of amplitude and asked whether the population of low amplitude (LA) segments displayed the expected characteristics of OFF periods. Results Average LA segment length was comparable to previous reports for OFF periods but varied considerably, from as short as 8 ms to > 1 s. LA segments were longer and occurred more frequently in NREM but shorter LA segments also occurred in half of rapid eye movement sleep (REM) epochs and occasionally during wakefulness. LA segments in all states were associated with a local field potential (LFP) slow wave that increased in amplitude with LA segment duration. We found that LA segments > 50 ms displayed a homeostatic rebound in incidence following sleep deprivation whereas short LA segments (< 50 ms) did not. The temporal organisation of LA segments was more coherent between channels located at a similar cortical depth. Conclusion We corroborate previous studies showing neural activity signals contain uniquely identifiable periods of low amplitude with distinct characteristics from the surrounding signal known as OFF periods and attribute the new characteristics of vigilance-state-dependent duration and duration-dependent homeostatic response to this phenomenon. This suggests that ON/OFF periods are currently underdefined and that their appearance is less binary than previously considered, instead representing a continuum.