Visual Attention to Dynamic Emotional Faces in Adults on the Autism Spectrum.

Using eye-tracking, we studied allocation of attention to faces where the emotional expression and eye-gaze dynamically changed in an ecologically-valid manner. We tested typically-developed (TD) adults low or high in autistic-like traits (Experiment 1), and adults with high-functioning autism (HFA; Experiment 2). All groups fixated more on the eyes than on any of the other facial area, regardless of emotion and gaze direction, though the HFA group fixated less on the eyes and more on the nose than TD controls. The sequence of dynamic facial changes affected the groups similarly, with reduced attention to the eyes and increased attention to the mouth. The results suggest that dynamic emotional face scanning patterns are stereotypical and differ only modestly between TD and HFA adults.

Semantic interpretability does not influence masked priming effects.

Much of the recent masked nonword priming literature demonstrates no difference in priming between affixed and non-affixed nonword primes (e.g., maskity-MASK vs. maskond-MASK). A possible explanation for the absence of a difference is that studies have used affixed primes which were semantically uninterpretable. Therefore, this explanation indicates semantic interpretability plays a fundamental role in masked priming. To test this account, we conducted an experiment using the masked priming paradigm in the lexical decision task. We compared responses with targets which were preceded by one of four primes types: (1) interpretable affixed nonwords (e.g., maskless-MASK), (2) uninterpretable affixed nonwords (e.g., maskity-MASK), (3) non-affixed nonwords (e.g., maskond-MASK), and (4) unrelated words (e.g., tubeful-MASK). Our results follow the trend of finding no difference between affixed and non-affixed primes. Critically, however, we observed no difference in priming between uninterpretable and interpretable affixed primes. Thus, our results suggest that semantic interpretability does not influence masked priming.

Reasons to doubt the generalizability, reliability, and diagnosticity of fast mapping (FM) for rapid lexical integration.

The possibility of fast mapping (FM) promoting rapid lexical integration challenges complementary systems accounts of word learning. Here, we first question the diagnosticity of orthographic lexical competition prior to sleep as an indicator of lexical integration, given emerging evidence that the same pre-sleep effect can be found with explicit learning paradigms. Second, we describe a study that showed no evidence of accelerated lexical integration for spoken-word learning. This study also found no FM advantage when written materials were used . Taken together, the evidence does not convincingly demonstrate that FM can accelerate lexical integration in healthy adults.

Why would a special FM process exist in adults, when it does not appear to exist in children?

Cooper Greve, and Henson (this issue)  caution restraint before accepting that a fast mapping (FM) process exists in adults. We welcome this, but would also add that the original rationale for studying FM in adults is not currently supported by developmental research. Despite the claims of several adult FM researchers, there is little evidence from developmental word learning research for a special hippocampus-independent FM process critical for children's word learning.

Sleep preserves original and distorted memory traces.

Retrieval facilitates the long-term retention of memories, but may also enable stored representations to be updated with new information that is available at the time of retrieval. However, if information integrated during retrieval is erroneous, future recall can be impaired: a phenomenon known as retrieval-induced distortion (RID). Whether RID causes an "overwriting" of existing memory traces or leads to the co-existence of original and distorted memory traces is unknown. Because sleep enhances memory consolidation, the effects of sleep after RID can provide novel insights into the structure of updated memories. As such, we investigated the effects of sleep on memory consolidation following RID. Participants encoded word locations and were then tested before (T1) and after (T2) an interval of sleep or wakefulness. At T2, the majority of words were placed closer to the locations retrieved at T1 than to the studied locations, consistent with RID. After sleep compared with after wake, the T2-retrieved locations were closer to both the studied locations and the T1-retrieved locations. These findings suggest that RID leads to the formation of an additional memory trace that corresponds to a distorted variant of the same encoding event, which is strengthened alongside the original trace during sleep. More broadly, these data provide evidence for the importance of sleep in the preservation and adaptive updating of memories.

Mechanisms of Memory Retrieval in Slow-Wave Sleep.

Study Objectives: Memories are strengthened during sleep. The benefits of sleep for memory can be enhanced by re-exposing the sleeping brain to auditory cues; a technique known as targeted memory reactivation (TMR). Prior studies have not assessed the nature of the retrieval mechanisms underpinning TMR: the matching process between auditory stimuli encountered during sleep and previously encoded memories. We carried out two experiments to address this issue. Methods: In Experiment 1, participants associated words with verbal and nonverbal auditory stimuli before an overnight interval in which subsets of these stimuli were replayed in slow-wave sleep. We repeated this paradigm in Experiment 2 with the single difference that the gender of the verbal auditory stimuli was switched between learning and sleep. Results: In Experiment 1, forgetting of cued (vs. noncued) associations was reduced by TMR with verbal and nonverbal cues to similar extents. In Experiment 2, TMR with identical nonverbal cues reduced forgetting of cued (vs. noncued) associations, replicating Experiment 1. However, TMR with nonidentical verbal cues reduced forgetting of both cued and noncued associations. Conclusions: These experiments suggest that the memory effects of TMR are influenced by the acoustic overlap between stimuli delivered at training and sleep. Our findings hint at the existence of two processing routes for memory retrieval during sleep. Whereas TMR with acoustically identical cues may reactivate individual associations via simple episodic matching, TMR with nonidentical verbal cues may utilize linguistic decoding mechanisms, resulting in widespread reactivation across a broad category of memories.

The Benefits of Targeted Memory Reactivation for Consolidation in Sleep are Contingent on Memory Accuracy and Direct Cue-Memory Associations.

STUDY OBJECTIVES: To investigate how the effects of targeted memory reactivation (TMR) are influenced by memory accuracy prior to sleep and the presence or absence of direct cue-memory associations. METHODS: 30 participants associated each of 50 pictures with an unrelated word and then with a screen location in two separate tasks. During picture-location training, each picture was also presented with a semantically related sound. The sounds were therefore directly associated with the picture locations but indirectly associated with the words. During a subsequent nap, half of the sounds were replayed in slow wave sleep (SWS). The effect of TMR on memory for the picture locations (direct cue-memory associations) and picture-word pairs (indirect cue-memory associations) was then examined. RESULTS: TMR reduced overall memory decay for recall of picture locations. Further analyses revealed a benefit of TMR for picture locations recalled with a low degree of accuracy prior to sleep, but not those recalled with a high degree of accuracy. The benefit of TMR for low accuracy memories was predicted by time spent in SWS. There was no benefit of TMR for memory of the picture-word pairs, irrespective of memory accuracy prior to sleep. CONCLUSIONS: TMR provides the greatest benefit to memories recalled with a low degree of accuracy prior to sleep. The memory benefits of TMR may also be contingent on direct cue-memory associations.

Event processing in the visual world: Projected motion paths during spoken sentence comprehension.

Motion events in language describe the movement of an entity to another location along a path. In 2 eye-tracking experiments, we found that comprehension of motion events involves the online construction of a spatial mental model that integrates language with the visual world. In Experiment 1, participants listened to sentences describing the movement of an agent to a goal while viewing visual scenes depicting the agent, goal, and empty space in between. Crucially, verbs suggested either upward (e.g., jump) or downward (e.g., crawl) paths. We found that in the rare event of fixating the empty space between the agent and goal, visual attention was biased upward or downward in line with the verb. In Experiment 2, visual scenes depicted a central obstruction, which imposed further constraints on the paths and increased the likelihood of fixating the empty space between the agent and goal. The results from this experiment corroborated and refined the previous findings. Specifically, eye-movement effects started immediately after hearing the verb and were in line with data from an additional mouse-tracking task that encouraged a more explicit spatial reenactment of the motion event. In revealing how event comprehension operates in the visual world, these findings suggest a mental simulation process whereby spatial details of motion events are mapped onto the world through visual attention. The strength and detectability of such effects in overt eye-movements is constrained by the visual world and the fact that perceivers rarely fixate regions of empty space. (PsycINFO Database Record

Markers of automaticity in sleep-associated consolidation of novel words.

Two experiments investigated effects of sleep on consolidation and integration of novel form-meaning mappings using size congruity and semantic distance paradigms. Both paradigms have been used in previous studies to measure automatic access to word meanings. When participants compare semantic or physical font size of written word-pairs (e.g. BEE-COW), judgments are typically faster if relative sizes are congruent across both dimensions. Semantic distance effects are also found for wellestablished words, with semantic size judgements faster for pairs that differ substantially on this dimension. English-speaking participants learned novel form-meaning mappings with Mandarin (Experiment 1) or Malay (Experiment 2) words and were tested following overnight sleep or a similar duration awake. Judgements on English words controlled for circadian effects. The sleep group demonstrated selective stronger size congruity and semantic distance effects for novel word-pairs. This benefit occurred in Experiment 1 for semantic size comparisons of novel words, and in Experiment 2 on comparisons where novel pairs had large distances and font differences (for congruity effects) or in congruent trials (for semantic distance effects). Conversely, these effects were equivalent across sleep and wake for English words. Experiment 2 included polysomnography data and revealed that changes in the strength of semantic distance and congruity effects were positively correlated with slow-wave sleep and sleep spindles respectively. These findings support systems consolidation accounts of declarative learning and suggest that sleep plays an active role in integrating new words with existing knowledge, resulting in increased automatic access of the acquired knowledge.

Can hyper-synchrony in meditation lead to seizures? Similarities in meditative and epileptic brain states.

Meditation is used worldwide by millions of people for relaxation and stress relief. Given sufficient practice, meditators may also experience a variety of altered states of consciousness. These states can lead to a variety of unusual experiences, including physical, emotional and psychic disturbances. This paper highlights the correspondences between brain states associated with these experiences and the symptoms and neurophysiology of epileptic simple partial seizures. Seizures, like meditation practice, can result in both positive and negative experiences. The neurophysiology and chemistry underlying simple partial seizures are characterised by a high degree of excitability and high levels of neuronal synchrony in gamma-band brain activity. Following a survey of the literature that shows that meditation practice is also linked to high power gamma activity, an account of how meditation could cause such activity is provided. This paper discusses the diagnostic challenges for the claim that meditation practices lead to brain states similar to those found in epileptic seizures, and seeks to develop our understanding of the range of pathological and non-pathological states that result from a hyper-excited and hyper-synchronous brain.

Sleep underpins the plasticity of language production.

The constraints that govern acceptable phoneme combinations in speech perception and production have considerable plasticity. We addressed whether sleep influences the acquisition of new constraints and their integration into the speech-production system. Participants repeated sequences of syllables in which two phonemes were artificially restricted to syllable onset or syllable coda, depending on the vowel in that sequence. After 48 sequences, participants either had a 90-min nap or remained awake. Participants then repeated 96 sequences so implicit constraint learning could be examined, and then were tested for constraint generalization in a forced-choice task. The sleep group, but not the wake group, produced speech errors at test that were consistent with restrictions on the placement of phonemes in training. Furthermore, only the sleep group generalized their learning to new materials. Polysomnography data showed that implicit constraint learning was associated with slow-wave sleep. These results show that sleep facilitates the integration of new linguistic knowledge with existing production constraints. These data have relevance for systems-consolidation models of sleep.

The selective role of premotor cortex in speech perception: a contribution to phoneme judgements but not speech comprehension.

Several accounts of speech perception propose that the areas involved in producing language are also involved in perceiving it. In line with this view, neuroimaging studies show activation of premotor cortex (PMC) during phoneme judgment tasks; however, there is debate about whether speech perception necessarily involves motor processes, across all task contexts, or whether the contribution of PMC is restricted to tasks requiring explicit phoneme awareness. Some aspects of speech processing, such as mapping sounds onto meaning, may proceed without the involvement of motor speech areas if PMC specifically contributes to the manipulation and categorical perception of phonemes. We applied TMS to three sites-PMC, posterior superior temporal gyrus, and occipital pole-and for the first time within the TMS literature, directly contrasted two speech perception tasks that required explicit phoneme decisions and mapping of speech sounds onto semantic categories, respectively. TMS to PMC disrupted explicit phonological judgments but not access to meaning for the same speech stimuli. TMS to two further sites confirmed that this pattern was site specific and did not reflect a generic difference in the susceptibility of our experimental tasks to TMS: stimulation of pSTG, a site involved in auditory processing, disrupted performance in both language tasks, whereas stimulation of occipital pole had no effect on performance in either task. These findings demonstrate that, although PMC is important for explicit phonological judgments, crucially, PMC is not necessary for mapping speech onto meanings.

To Dash or to Dawdle: Verb-Associated Speed of Motion Influences Eye Movements during Spoken Sentence Comprehension.

In describing motion events verbs of manner provide information about the speed of agents or objects in those events. We used eye tracking to investigate how inferences about this verb-associated speed of motion would influence the time course of attention to a visual scene that matched an event described in language. Eye movements were recorded as participants heard spoken sentences with verbs that implied a fast ("dash") or slow ("dawdle") movement of an agent towards a goal. These sentences were heard whilst participants concurrently looked at scenes depicting the agent and a path which led to the goal object. Our results indicate a mapping of events onto the visual scene consistent with participants mentally simulating the movement of the agent along the path towards the goal: when the verb implies a slow manner of motion, participants look more often and longer along the path to the goal; when the verb implies a fast manner of motion, participants tend to look earlier at the goal and less on the path. These results reveal that event comprehension in the presence of a visual world involves establishing and dynamically updating the locations of entities in response to linguistic descriptions of events.

Lexical integration of novel words without sleep.

Learning a new word involves integration with existing lexical knowledge. Previous work has shown that sleep-associated memory consolidation processes are important for the engagement of novel items in lexical competition. In 3 experiments we used spaced exposure regimes to investigate memory for novel words and whether lexical integration can occur within a single day. The degree to which a new spoken word (e.g., cathedruke) engaged in lexical competition with established phonological neighbors (e.g., cathedral) was employed as a marker for lexical integration. We found evidence for improvements in recognition and cued recall following a time period including sleep, but we also found lexical competition effects emerging within a single day. Spaced exposure to novel words on its own did not bring about this within-day lexical competition effect (Experiment 2), which instead occurred with either spaced or massed exposure to novel words, provided that there was also spaced exposure to the phonological neighbors (Experiments 1 and 3). Although previous studies have indicated that sleep-dependent memory consolidation may be sufficient for lexical integration, our results show it is not a necessary precondition.

Atypical neuroleptic malignant syndrome: diagnostic controversies and considerations.

Neuroleptic malignant syndrome (NMS) is a serious and potentially fatal adverse effect of antipsychotic drugs. The diagnosis of NMS commonly requires core symptoms of hyperthermia and muscle rigidity. Although diagnostic criteria for NMS have been established and are widely accepted and used, it should be recognized that atypical presentations pose a diagnostic dilemma, as hyperthermia and/or muscle rigidity may be absent or develop slowly over several days, leading to impairment or a significant delay in diagnosis and treatment. Evidence from case reports and retrospective evaluations supports a concept of atypical NMS, particularly with regard to treatment with atypical antipsychotics. However, it remains unclear whether these atypical presentations represent early or impending NMS. Furthermore, it is unclear whether dysfunction in other neurotransmitter systems, in addition to dopamine, may be involved in the pathogenesis of NMS induced by atypical antipsychotics. In patients receiving any antipsychotic, clinicians should carefully evaluate any features of NMS and should not prematurely exclude a diagnosis of NMS in cases where severe rigidity or hyperthermia is not initially apparent.

Spatial and linguistic aspects of visual imagery in sentence comprehension.

There is mounting evidence that language comprehension involves the activation of mental imagery of the content of utterances (Barsalou, 1999; Bergen, Chang, & Narayan, 2004; Bergen, Narayan, & Feldman, 2003; Narayan, Bergen, & Weinberg, 2004; Richardson, Spivey, McRae, & Barsalou, 2003; Stanfield & Zwaan, 2001; Zwaan, Stanfield, & Yaxley, 2002). This imagery can have motor or perceptual content. Three main questions about the process remain under-explored, however. First, are lexical associations with perception or motion sufficient to yield mental simulation, or is the integration of lexical semantics into larger structures, like sentences, necessary? Second, what linguistic elements (e.g., verbs, nouns, etc.) trigger mental simulations? Third, how detailed are the visual simulations that are performed? A series of behavioral experiments address these questions, using a visual object categorization task to investigate whether up- or down-related language selectively interferes with visual processing in the same part of the visual field (following Richardson et al., 2003). The results demonstrate that either subject nouns or main verbs can trigger visual imagery, but only when used in literal sentences about real space-metaphorical language does not yield significant effects-which implies that it is the comprehension of the sentence as a whole and not simply lexical associations that yields imagery effects. These studies also show that the evoked imagery contains detail as to the part of the visual field where the described scene would take place.

Use of modafinil for the treatment of attention deficit/hyperactivity disorder.

OBJECTIVE: To review the evidence for the use of modafinil in the treatment of attention deficit/hyperactivity disorder (ADHD). DATA SOURCES: A MEDLINE search (January 1990-May 2006) was conducted using MeSH terms ADHD and modafinil. The search was limited to English-language articles on clinical trials in humans. The Cochrane Database was also searched. STUDY SELECTION AND DATA EXTRACTION: The literature search yielded 4 randomized clinical trials. DATA SYNTHESIS: The use of modafinil in the treatment of ADHD is associated with significant improvements in primary outcome measures used to assess the status of patients diagnosed with ADHD. Several aspects of cognitive function in ADHD patients also appear to improve following modafinil treatment. Modafinil shows a favorable adverse effect profile. Insomnia and headache were the most common adverse effects, seen in approximately 20% of treated individuals. However, it has not been demonstrated that the beneficial effects of modafinil are maintained with chronic administration. CONCLUSIONS: Modafinil may be a viable option for some patients in the treatment of ADHD, perhaps those for whom standard ADHD therapies have not been successful or tolerated. There remains a need for additional large, long-term studies using flexible titration methods to optimize the dose of modafinil to establish safety and efficacy, as well as head-to-head comparisons between modafinil and both long- and short-acting stimulants to determine the role of modafinil in the treatment of ADHD.