Closing the gap between science and management of cold-water refuges in rivers and streams

Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive management approaches are needed that consider interlinked physical, biological, and social factors of cold-water refuges. We review current understanding of cold-water refuges, identify gaps between science and management, and evaluate policies aimed at protecting thermally sensitive species. Existing policies include designating cold-water habitats, restricting fishing during warm periods, and implementing threshold temperature standards or guidelines. However, these policies are rare and uncoordinated across spatial scales and often do not consider input from Indigenous peoples. We propose that cold-water refuges be managed as distinct operational landscape units, which provide a social and ecological context that is relevant at the watershed scale. These operational landscape units provide the foundation for an integrated framework that links science and management by (1) mapping and characterizing cold-water refuges to prioritize management and conservation actions, (2) leveraging existing and new policies, (3) improving coordination across jurisdictions, and (4) implementing adaptive management practices across scales. Our findings show that while there are many opportunities for scientific advancement, the current state of the sciences is sufficient to inform policy and management. Our proposed framework provides a path forward for managing and protecting cold-water refuges using existing and new policies to protect coldwater organisms in the face of global change.

An emerging youth-centered model of community resilience in communities impacted by gun violence: Power through Black Community and Unity

Studies commonly examine resilience as an outcome by way of measuring the degree to which protective factors maintain individuals' well-being despite the presence of significant risk. In this study, we developed a model of community resilience that centered the voices of Black youth. Using data collected as part of a 3-year, youth participatory action research project, we developed a model that focuses on what 11 Black youth perceive and believe contributes to community resilience through their investigation of problems and solutions related to community gun violence. Findings from a constructivist grounded theory analysis of multiple data sources (e.g., field notes, transcribed group discussions, youth photovoice activities) revealed our developing model of community resilience: Power through Black Community and Unity. Specifically, Power through Black Community and Unity was a core category that reflected the importance of care, support, and safety as strengths in the community's current response and resilience to gun violence, and future aspects the community could develop to increase community resilience to gun violence. This core category emerged in three subsequent ways: Collective Care, "Seeing Beyond the Bad," and Supportive Teen Spaces. This study illustrates potential pathways that youth service agencies and community practitioners can consider enhancing in their programming to promote resilience in their communities.

Development of selective attention in preschool-age children from lower socioeconomic status backgrounds

Although differences in selective attention skills have been identified in children from lower compared to higher socioeconomic status (SES) backgrounds, little is known about these differences in early childhood, a time of rapid attention development. The current study evaluated the development of neural systems for selective attention in children from lower SES backgrounds. Event-related potentials (ERPs) were acquired from 33 children from lower SES and 14 children from higher SES backgrounds during a dichotic listening task. The lower SES group was followed longitudinally for one year. At age four, the higher SES group exhibited a significant attention effect (larger ERP response to attended compared to unattended condition), an effect not observed in the lower SES group. At age five, the lower SES group exhibited a significant attention effect comparable in overall magnitude to that observed in the 4-year-old higher SES group, but with poorer distractor suppression (larger response to the unattended condition). Together, these findings suggest both a maturational delay and divergent developmental pattern in neural mechanisms for selective attention in young children from lower compared to higher SES backgrounds. Furthermore, these findings highlight the importance of studying neurodevelopment within narrow age ranges and in children from diverse backgrounds.

Development and Validation of the Korean Rape Myth Acceptance Scale

The purpose of this investigation was to develop a culturally relevant rape myth acceptance scale for Koreans. Three studies on the Korean Rape Myth Acceptance Scale (KRMAS) with approximately 1,000 observations provide initial validity and reliability. Specifically, results from exploratory and confirmatory factor analyses support four subscales: myths about rape survivors, rape perpetrators, the impact of rape, and rape as spontaneous. The KRMAS was validated with student and community samples and a factorial invariance analysis provided evidence for the factor structure across men and women. The KRMAS total score was positively related to the Attitudes Toward Sex Role Scale–Korean and the Acceptance of Violence Scale, indicating that greater endorsement of rape myth acceptance was related to greater levels of attitudes toward traditional sex roles and violence against women. Implications of the findings and future research directions are provided.

Atypical auditory refractory periods in children from lower socio-economic status backgrounds: ERP evidence for a role of selective attention

Previous neuroimaging studies indicate that lower socio-economic status (SES) is associated with reduced effects of selective attention on auditory processing. Here, we investigated whether lower SES is also associated with differences in a stimulus-driven aspect of auditory processing: the neural refractory period, or reduced amplitude response at faster rates of stimulus presentation. Thirty-two children aged 3 to 8 years participated, and were divided into two SES groups based on maternal education. Event-related brain potentials were recorded to probe stimuli presented at interstimulus intervals (ISIs) of 200, 500, or 1000 ms. These probes were superimposed on story narratives when attended and ignored, permitting a simultaneous experimental manipulation of selective attention. Results indicated that group differences in refractory periods differed as a function of attention condition. Children from higher SES backgrounds showed full neural recovery by 500 ms for attended stimuli, but required at least 1000 ms for unattended stimuli. In contrast, children from lower SES backgrounds showed similar refractory effects to attended and unattended stimuli, with full neural recovery by 500 ms. Thus, in higher SES children only, one functional consequence of selective attention is attenuation of the response to unattended stimuli, particularly at rapid ISIs, altering basic properties of the auditory refractory period. Together, these data indicate that differences in selective attention impact basic aspects of auditory processing in children from lower SES backgrounds.

Combining demographic and genetic factors to assess population vulnerability in stream species

Accelerating climate change and other cumulative stressors create an urgent need to understand the influence of environmental variation and landscape features on the connectivity and vulnerability of freshwater species. Here, we introduce a novel modeling framework for aquatic systems that integrates spatially explicit, individual-based, demographic and genetic (demogenetic) assessments with environmental variables. To show its potential utility, we simulated a hypothetical network of 19 migratory riverine populations (e.g., salmonids) using a riverscape connectivity and demogenetic model (CDFISH). We assessed how stream resistance to movement (a function of water temperature, fluvial distance, and physical barriers) might influence demogenetic connectivity, and hence, population vulnerability. We present demographic metrics (abundance, immigration, and change in abundance) and genetic metrics (diversity, differentiation, and change in differentiation), and combine them into a single vulnerability index for identifying populations at risk of extirpation. We considered four realistic scenarios that illustrate the relative sensitivity of these metrics for early detection of reduced connectivity: (1) maximum resistance due to high water temperatures throughout the network, (2) minimum resistance due to low water temperatures throughout the network, (3) increased resistance at a tributary junction caused by a partial barrier, and (4) complete isolation of a tributary, leaving resident individuals only. We then applied this demogenetic framework using empirical data for a bull trout (Salvelinus confluentus) metapopulation in the upper Flathead River system, Canada and USA, to assess how current and predicted future stream warming may influence population vulnerability. Results suggest that warmer water temperatures and associated barriers to movement (e.g., low flows, dewatering) are predicted to fragment suitable habitat for migratory salmonids, resulting in the loss of genetic diversity and reduced numbers in certain vulnerable populations. This demogenetic simulation framework, which is illustrated in a web-based interactive mapping prototype, should be useful for evaluating population vulnerability in a wide variety of dendritic and fragmented riverscapes, helping to guide conservation and management efforts for freshwater species.

Implicit and explicit second language training recruit common neural mechanisms for syntactic processing

In contrast to native language acquisition, adult second-language (L2) acquisition occurs under highly variable learning conditions. Although most adults acquire their L2 at least partially through explicit instruction, as in a classroom setting, many others acquire their L2 primarily through implicit exposure, as is typical of an immersion environment. Whether these differences in acquisition environment play a role in determining the neural mechanisms that are ultimately recruited to process L2 grammar has not been well characterized. This study investigated this issue by comparing the ERP response to novel L2 syntactic rules acquired under conditions of implicit exposure and explicit instruction, using a novel laboratory language-learning paradigm. Native speakers tested on these stimuli showed a biphasic response to syntactic violations, consisting of an earlier negativity followed by a later P600 effect. After merely an hour of training, both implicitly and explicitly trained learners who were capable of detecting grammatical violations also elicited P600 effects. In contrast, learners who were unable to discriminate between grammatically correct and incorrect sentences did not show significant P600 effects. The magnitude of the P600 effect was found to correlate with learners' behavioral proficiency. Behavioral measures revealed that successful learners from both the implicit and explicit groups gained explicit, verbalizable knowledge about the L2 grammar rules. Taken together, these results indicate that late, controlled mechanisms indexed by the P600 play a crucial role in processing a late-learned L2 grammar, regardless of training condition. These findings underscore the remarkable plasticity of later, attention-dependent processes and their importance in lifelong learning.

The neurobiology of rhyme judgment by deaf and hearing adults: an ERP study

We used electrophysiology to determine the time course and distribution of neural activation during an English word rhyme task in hearing and congenitally deaf adults. Behavioral performance by hearing participants was at ceiling and their ERP data replicated two robust effects repeatedly observed in the literature. First, a sustained negativity, termed the contingent negative variation, was elicited following the first stimulus word. This negativity was asymmetric, being more negative over the left than right sites. The second effect we replicated in hearing participants was an enhanced negativity (N450) to nonrhyming second stimulus words. This was largest over medial, parietal regions of the right hemisphere. Accuracy on the rhyme task by the deaf group as a whole was above chance level, yet significantly poorer than hearing participants. We examined only ERP data from deaf participants who performed the task above chance level (n = 9). We observed indications of subtle differences in ERP responses between deaf and hearing groups. However, overall the patterns in the deaf group were very similar to that in the hearing group. Deaf participants, just as hearing participants, showed greater negativity to nonrhyming than rhyming words. Furthermore the onset latency of this effect was the same as that observed in hearing participants. Overall, the neural processes supporting explicit phonological judgments are very similar in deaf and hearing people, despite differences in the modality of spoken language experience. This supports the suggestion that phonological processing is to a large degree amodal or supramodal.

Examining the role of attention and instruction in at-risk kindergarteners: electrophysiological measures of selective auditory attention before and after an early literacy intervention

Several studies report that adults and adolescents with reading disabilities also experience difficulties with selective attention. In the present study, event-related brain potentials (ERPs) were used to examine the neural mechanisms of selective attention in kindergarten children at risk for reading disabilities (AR group, n = 8) or on track in early literacy skills (OT group, n = 6) across the first semester of kindergarten. The AR group also received supplemental instruction with the Early Reading Intervention (ERI). Following ERI, the AR group demonstrated improved skills on standardized early literacy measures such that there were no significant differences between the AR and OT groups at posttest or winter follow-up. Analysis of the ERP data revealed that at the start of kindergarten, the AR group displayed reduced effects of attention on sensorineural processing compared to the OT group. Following intervention, this difference between groups disappeared, with the AR group only showing improvements in the effect of attention on sensorineural processing. These data indicate that the neural mechanisms of selective attention are atypical in kindergarten children at risk for reading failure but can be improved by effective reading interventions.

Electrophysiological evidence for attenuated auditory recovery cycles in children with specific language impairment

Previous research indicates that at least some children with specific language impairment (SLI) show a reduced neural response when non-linguistic tones were presented at rapid rates. However, this past research has examined older children, and it is unclear whether such deficits emerge earlier in development. It is also unclear whether atypical refractory effects differ for linguistic versus non-linguistic stimuli or can be explained by deficits in selective auditory attention reported among children with SLI. In the present study, auditory refractory periods were compared in a group of 24 young children with SLI (age 3-8 years) and 24 matched control children. Event-related brain potentials (ERPs) were recorded and compared to 100 ms linguistic and non-linguistic probe stimuli presented at inter-stimulus intervals (ISIs) of 200, 500, or 1000 ms. These probes were superimposed on story narratives when attended and ignored, permitting an experimental manipulation of selective attention within the same paradigm. Across participants, clear refractory effects were observed with this paradigm, evidenced as a reduced amplitude response from 100 to 200 ms at shorter ISIs. Children with SLI showed reduced amplitude ERPs relative to the typically-developing group at only the shortest, 200 ms, ISI and this difference was over the left-hemisphere for linguistic probes and over the right-hemisphere for non-linguistic probes. None of these effects was influenced by the direction of selective attention. Taken together, these findings suggest that deficits in the neural representation of rapidly presented auditory stimuli may be one risk factor for atypical language development.

Dissociable mechanisms supporting awareness: the P300 and gamma in a linguistic attentional blink task

As demonstrated by the attentional blink (AB) phenomenon, awareness for attended stimuli is governed by sharp capacity limits. We used a linguistic AB task to investigate the neural mechanisms that underlie failures of awareness, examining both event-related potentials and oscillatory brain activity to correctly reported and missed second targets (T2s) presented after a correctly reported first target (T1) in a rapid visual stream of distractors. Correctly reported targets occurring at a short lag (250 ms) after T1-within the classic AB period-elicited enhanced late gamma activity relative to incorrectly reported targets but showed no P300 modulation relative to missed targets. In contrast, correctly reported targets presented at a long lag (830 ms)-outside the classic AB period-elicited a greater P300 component but did not significantly modulate oscillatory activity. This double dissociation suggests that there are multiple neural mechanisms supporting awareness that may operate in parallel. Either the P300 or the gamma can index impairment in the cascade of processing leading to a target's entry into awareness. We conclude that the P300 and gamma activity reflect functionally distinct neural mechanisms, each of which plays an independent role in awareness.

Implicit and explicit mechanisms of word learning in a narrative context: an event-related potential study

The vast majority of word meanings are learned simply by extracting them from context rather than by rote memorization or explicit instruction. Although this skill is remarkable, little is known about the brain mechanisms involved. In the present study, ERPs were recorded as participants read stories in which pseudowords were presented multiple times, embedded in consistent, meaningful contexts (referred to as meaning condition, M+) or inconsistent, meaningless contexts (M-). Word learning was then assessed implicitly using a lexical decision task and explicitly through recall and recognition tasks. Overall, during story reading, M- words elicited a larger N400 than M+ words, suggesting that participants were better able to semantically integrate M+ words than M- words throughout the story. In addition, M+ words whose meanings were subsequently correctly recognized and recalled elicited a more positive ERP in a later time window compared with M+ words whose meanings were incorrectly remembered, consistent with the idea that the late positive component is an index of encoding processes. In the lexical decision task, no behavioral or electrophysiological evidence for implicit priming was found for M+ words. In contrast, during the explicit recognition task, M+ words showed a robust N400 effect. The N400 effect was dependent upon recognition performance, such that only correctly recognized M+ words elicited an N400. This pattern of results provides evidence that the explicit representations of word meanings can develop rapidly, whereas implicit representations may require more extensive exposure or more time to emerge.

The role of awareness in semantic and syntactic processing: an ERP attentional blink study

An important question in the study of language is to what degree semantic and syntactic processes are automatic or controlled. This study employed an attentional blink (AB) paradigm to manipulate awareness in the processing of target words in order to assess automaticity in semantic and syntactic processing. In the semantic block, targets occurring both within and outside the AB period elicited an N400. However, N400 amplitude was significantly reduced during the AB period, and missed targets did not elicit an N400. In the syntactic block, ERPs to targets occurring outside the AB period revealed a late negative syntactic incongruency effect, whereas ERPs to targets occurring within the AB period showed no effect of incongruency. The semantic results support the argument that the N400 primarily indexes a controlled, postlexical process. Syntactic findings suggest that the ERP response to some syntactic violations depends on awareness and availability of attentional resources.

Differences in the neural mechanisms of selective attention in children from different socioeconomic backgrounds: an event-related brain potential study

Previous research indicates that children from lower socioeconomic backgrounds show deficits in aspects of attention, including a reduced ability to filter irrelevant information and to suppress prepotent responses. However, less is known about the neural mechanisms of group differences in attention, which could reveal the stages of processing at which attention deficits arise. The present study examined this question using an event-related brain potential (ERP) measure of selective auditory attention. Thirty-two children aged from 3 to 8 years participated in the study. Children were cued to attend selectively to one of two simultaneously presented narrative stories. The stories differed in location (left/right speaker), narration voice (male/female), and content. ERPs were recorded to linguistic and non-linguistic probe stimuli embedded in the attended and unattended stories. Children whose mothers had lower levels of educational attainment (no college experience) showed reduced effects of selective attention on neural processing relative to children whose mothers had higher levels of educational attainment (at least some college). These differences occurred by 100 milliseconds after probe onset. Furthermore, the differences were related specifically to a reduced ability to filter irrelevant information (i.e. to suppress the response to sounds in the unattended channel) among children whose mothers had lower levels of education. These data provide direct evidence for differences in the earliest stages of processing within neural systems mediating selective attention in children from different socioeconomic backgrounds. Results are discussed in the context of intervention programs aimed at improving attention and self-regulation abilities in children at-risk for school failure.

Neural mechanisms of selective auditory attention are enhanced by computerized training: electrophysiological evidence from language-impaired and typically developing children

Recent proposals suggest that some interventions designed to improve language skills might also target or train selective attention. The present study examined whether six weeks of high-intensity (100 min/day) training with a computerized intervention program designed to improve language skills would also influence neural mechanisms of selective auditory attention previously shown to be deficient in children with specific language impairment (SLI). Twenty children received computerized training, including 8 children diagnosed with SLI and 12 children with typically developing language. An additional 13 children with typically developing language received no specialized training (NoTx control group) but were tested and retested after a comparable time period to control for maturational and test-retest effects. Before and after training (or a comparable delay period for the NoTx control group), children completed standardized language assessments and an event-related brain potential (ERP) measure of selective auditory attention. Relative to the NoTx control group, children receiving training showed increases in standardized measures of receptive language. In addition, children receiving training showed larger increases in the effects of attention on neural processing following training relative to the NoTx control group. The enhanced effect of attention on neural processing represented a large effect size (Cohen's d=0.8), and was specific to changes in signal enhancement of attended stimuli. These findings indicate that the neural mechanisms of selective auditory attention, previously shown to be deficient in children with SLI, can be remediated through training and can accompany improvements on standardized measures of language.

Neurophysiological evidence for selective auditory attention deficits in children with specific language impairment

Recent behavioral studies suggest that children with poor language abilities have difficulty with attentional filtering, or noise exclusion. However, as behavioral performance represents the summed activity of multiple stages of processing, the temporal locus of the filtering deficit remains unclear. Here, we used an event-related potential (ERP) paradigm to compare the earliest mechanisms of selective auditory attention in 12 children with specific language impairment (SLI) and 12 matched control children. Participants were cued to attend selectively to one of two simultaneously presented narrative stories. The stories differed in location (left/right speaker), narration voice (male/female), and content. ERPs were recorded to linguistic and nonlinguistic probe stimuli embedded in the attended and unattended story. By 100 ms, typically developing children showed an amplification of the sensorineural response to attended as compared to unattended stimuli. In contrast, children with SLI showed no evidence of sensorineural modulation with attention, despite behavioral performance indicating that they were performing the task as directed. These data are the first to show that SLI children have marked and specific deficits in the neural mechanisms of attention and, further, localize the timing of the attentional deficit to the earliest stages of sensory processing. Deficits in the effects of selective attention on early sensorineural processing may give rise to the diverse set of sensory and linguistic impairments in SLI children.

Neuroplasticity as a Double-edged Sword: Deaf Enhancements and Dyslexic Deficits in Motion Processing

We examined the hypothesis that aspects of processing that are most modifiable by experience (i.e., “plastic”) display the most vulnerability in developmental disorders and the most compensatory enhancement after sensory deprivation. A large literature reports that motion processing and magnocellular visual function is selectively deficient in dyslexia. A smaller literature reports enhancements in such functions in deaf individuals. However, studies with dyslexic and deaf individuals have used different experimental paradigms to assess visual function, and no research has yet examined both sides of modifiability (i.e., enhancements and deficits) using the same experimental paradigm. In the present research, visual function was compared in dyslexic (n = 15), deaf (n = 17), and control adults by using automated peripheral kinetic and foveal static perimetry. In the kinetic perimetry task, the dyslexic group showed deficits ( p < .003), whereas the deaf group showed enhancements ( p < .001) for detecting moving light points in the periphery. In the foveal static perimetry task, neither the dyslexic ( p = .866) nor the deaf ( p = .632) group differed significantly from controls in foveal contrast sensitivity thresholds, and no group or individual approached ceiling performance on this task. Taken together, the present data bridge previous literatures and suggest that motion processing tasks are selectively modifiable, either to decrement or enhancement, whereas foveal contrast sensitivity does not differ in dyslexic or deaf groups.

Exploring the association between color-blind racial ideology and multicultural counseling competencies

The authors examined the association between color-blind racial ideology and self-reported multicultural counseling competencies in 130 applied psychology students and mental health workers. Results from 1 sample (n = 79) indicated that greater levels of color-blind racial ideology as measured by the Color-Blind Racial Attitudes Scale (Neville, Lilly, Duran, Lee, & Browne, 2000) were (1) related to lower self-reported multicultural counseling awareness and knowledge as measured by the Multicultural Counseling Knowledge and Awareness Scale (MCKAS; Ponterotto, Gretchen, Utsey, Rieger, & Austin, 2002) and (2) accounted for a significant amount of variance in MCKAS scores over and above that explained by self-reported multicultural training, social desirability, and participant race. Findings from another sample also provided empirical support for the link between higher color-blind racial ideology and lower multicultural case conceptualization ability (n = 51), after controlling for the influence of the number of multicultural course(s) taken. Implications of the findings and future directions are provided.

Motion and color processing in school-age children and adults: an ERP study

Stimuli designed to selectively elicit motion or color processing were used in a developmental event-related potential study with adults and children aged 6, 7 and 8. A positivity at posterior site INZ (P-INZ) was greater to motion stimuli only in adults. The P1 and N1 were larger to color stimuli in both adults and children, but earlier to motion stimuli only in adults. Finally, the P2 was larger to color stimuli in adults but larger to motion stimuli in children, and earlier to motion stimuli only in children. The findings across components indicate development from middle childhood to adulthood in aspects of both the motion and color processing systems indexed by this paradigm, but are consistent with an hypothesis of a more protracted time course of development for the motion as compared to the color processing system.

ERP Nonword Rhyming Effects in Children and Adults

In a simple prime–target auditory rhyming event-related potential (ERP) paradigm with adults and 6-, 7-, and 8-year-old children, nonword stimuli (e.g., nin–rin, ked–voo) were used to investigate neurocognitive systems involved in rhyming and their development across the early school years. Even absent semantic content, the typical CNV to primes and late rhyming effect (RE) to targets were evident in all age groups. The RE consisted of a more negative response to nonrhyming targets as compared to rhyming targets over posterior sites, with a reversal of this pattern at lateral anterior sites. The hypothesis that the CNV indexes phonological memory processes was not well supported by correlation analyses conducted with the ERP measures and scores on standardized behavioral tests. However, the onset of the rhyming effect was later in those scoring lower on phonological awareness measures.

Human brain plasticity: evidence from sensory deprivation and altered language experience

The results from the language studies taken as a whole point to different developmental time courses and developmental vulnerabilities of aspects of grammatical and semantic/lexical processing. They thus provide support for conceptions of language that distinguish these subprocesses within language. Similarly, following auditory deprivation, processes associated with the dorsal visual pathway were more altered than were functions associated with the ventral pathway, providing support for conceptions of visual system organization that distinguish functions along these lines. Could the effects observed in blind and deaf adults be accounted for, at least in part, by the redundant connectivity of the immature human brain? One way we tested this hypothesis was to study the differentiation of visual and auditory sensory responses in normal development (Neville, 1995). In normal adults, auditory stimuli elicit ERP responses that are large over temporal brain regions but small or absent over occipital regions. By contrast, in 6-month-old children we observed that auditory ERPs are equally large over temporal and visual brain regions, consistent with the idea that there is less specificity and more redundancy of connections between the auditory and visual cortex at this time. Between 6 and 36 months, however, we observed a gradual decrease in the amplitude of the auditory ERP over visual areas, while the amplitude over the temporal areas was unchanged. These results suggest that early in human development, there exists a redundancy of connections between auditory and visual areas and that this overlap gradually decreases after birth. This loss of redundancy may be a boundary condition that determines when sensory deprivation can result in alterations in the organization of remaining sensory systems. The considerable variability in timing of sensitive periods may also be in part due to temporal differences in the occurrence of redundancy within different systems. Ongoing studies of infants and children employing different types of stimuli will test for the specificity of these effects (Mitchell et al., 1999). Differences in the degree of plasticity may also be due to differences in the overall level of redundant connectivity within different systems. For example, it may be that aspects of sensory systems that are specialized for high spatial acuity (e.g., central vision and central audition) exhibit fewer developmental redundancies, decreased modifiability and more specificity than those displaying less acuity and precision (e.g., peripheral representations within vision and audition). There is some evidence for this hypothesis within the visual system (Chalupa and Dreher, 1991). In addition, there may be molecular differences between systems displaying different levels and patterns of experience-dependent plasticity. It is of interest that all levels of the dorsal pathway of the visual system, which in the studies reviewed here shows a high level of modifiability, displays strong immunoreactivity for the monoclonal antibody CAT 301 in macaque monkeys (DeYoe et al., 1990). By contrast there is very little labeling within the ventral visual pathway. Moreover, the expression of CAT 301 immunoreactivity shows marked experience-dependent plasticity, suggesting it may play a role in the guidance and/or stabilization of synaptic structure (Sur et al., 1988). Further research along these lines within the auditory system and in animal models of sensory deprivation and other developmental disorders may elucidate the role of specific molecular factors in the developmental plasticity of different neural systems. A related, more general hypothesis that may account for the different patterns of plasticity within both vision and language is that systems employing fundamentally different learning mechanisms (perhaps mediated by different anatomical and molecular substrates) display different patterns of developmental plasticity. It may be that systems that display experience-dependent change throughout life, including the topography of sensory maps (Merzenich et al., 1988; Gilbert, 1995; Kaas, 1995), lexical acquisition (i.e. object-word associations), and the establishment of form, face, and object representations (i.e., ventral pathway functions) rely upon very general, associative learning mechanisms that permit learning and adaptation throughout life. By contrast, systems that are important for computing dynamically shifting relations among locations, objects and events (including the dorsal visual pathway and the systems of the brain that mediate grammar) appear dependent on and modifiable by experience primarily during more limited periods in development. This could account for both the greater developmental deficits and enhancements of dorsal pathway function following various developmental anomalies and for the greater effects of altered language experience on grammatical functions. Further research is necessary to characterize systems that become constrained in this way and those that can be modified throughout life. This type of developmental evidence can contribute to fundamental descriptions of the architecture of different cognitive systems and can guide future studies of the cellular and molecular mechanisms important in neuroplasticity. Additionally, in the long run, they may contribute to the design of educational and habilitative programs for both normally and abnormally developing children.

Speech processing activates visual cortex in congenitally blind humans

Neurophysiological recordings and neuroimaging data in blind and deaf animals and humans suggest that perceptual functions may be organized differently after sensory deprivation. It has been argued that neural plasticity contributes to compensatory performance in blind humans, such as faster speech processing. The present study employed functional magnetic resonance imaging (fMRI) to map language-related brain activity in congenitally blind adults. Participants listened to sentences, with either an easy or a more difficult syntactic structure, which were either semantically meaningful or meaningless. Results show that blind adults not only activate classical left-hemispheric perisylvian language areas during speech comprehension, as did a group of sighted adults, but that they additionally display an activation in the homologueous right-hemispheric structures and in extrastriate and striate cortex. Both the perisylvian and occipital activity varied as a function of syntactic difficulty and semantic content. The results demonstrate that the cerebral organization of complex cognitive systems such as the language system is significantly shaped by the input available.

Brain activation modulated by the comprehension of normal and pseudo-word sentences of different processing demands: a functional magnetic resonance imaging study

Recent data from lesion and brain imaging studies have questioned the well-established assumption of a close functional-anatomic link between syntax and Broca's area and semantics and Wernicke's area. In the present study we used functional magnetic resonance imaging (fMRI) to investigate the neuroanatomical correlates of semantic and syntactic functions and possible interdependencies between the related brain systems. In a completely crossed design we varied syntactic processing demands (easy vs difficult to process word order sequences) and the meaningfulness of sentences (real- vs pseudo-word sentences). In comparison to a backward speech condition we found an activation of the left perisylvian region, including the left inferior frontal cortex and the left superior and middle temporal gyri. Semantic in contrast to pseudo-word sentences elicited a stronger activation in both the anterior and the posterior perisylvian cortex. Syntactic difficulty had its strongest effect within the left inferior frontal region and this effect was more pronounced for semantic than nonsemantic speech. These results suggest that semantic and syntactic language functions are mediated by partly specialized brain systems but that there nevertheless exists a substantial functional overlap of the involved brain structures.

Impact of early deafness and early exposure to sign language on the cerebral organization for motion processing

This functional magnetic resonance imaging study investigated the impact of early auditory deprivation and/or use of a visuospatial language [American sign language (ASL)] on the organization of neural systems important in visual motion processing by comparing hearing controls with deaf and hearing native signers. Participants monitored moving flowfields under different conditions of spatial and featural attention. Recruitment of the motion-selective area MT-MST in hearing controls was observed to be greater when attention was directed centrally and when the task was to detect motion features, confirming previous reports that the motion network is selectively modulated by different aspects of attention. More importantly, we observed marked differences in the recruitment of motion-related areas as a function of early experience. First, the lateralization of MT-MST was found to shift toward the left hemisphere in early signers, suggesting that early exposure to ASL leads to a greater reliance on the left MT-MST. Second, whereas the two hearing populations displayed more MT-MST activation under central than peripheral attention, the opposite pattern was observed in deaf signers, indicating enhanced recruitment of MT-MST during peripheral attention after early deafness. Third, deaf signers, but neither of the hearing populations, displayed increased activation of the posterior parietal cortex, supporting the view that parietal functions are modified after early auditory deprivation. Finally, only in deaf signers did attention to motion result in enhanced recruitment of the posterior superior temporal sulcus, establishing for the first time in humans that this polymodal area is modified after early sensory deprivation. Together these results highlight the functional and regional specificity of neuroplasticity in humans.

Phase III randomized trial of gabapentin in patients with amyotrophic lateral sclerosis

BACKGROUND

Preclinical and clinical studies of gabapentin in patients with ALS led the authors to undertake a phase III randomized clinical trial.

METHODS

Patients were randomly assigned, in a double-blinded fashion, to receive oral gabapentin 3,600 mg or placebo daily for 9 months. The primary outcome measure was the average rate of decline in isometric arm muscle strength for those with two or more evaluations.

RESULTS

Two hundred four patients enrolled, 196 had two or more evaluations, and 128 patients completed the study. The mean rate of decline of the arm muscle strength was not significantly different between the groups. Moreover, there was no beneficial effect upon the rate of decline of other secondary measures (vital capacity, survival, ALS functional rating scale, timed walking) nor was there any symptomatic benefit. In fact, analysis of the combined data from the phase II and III trials revealed a significantly more rapid decline of forced vital capacity in patients treated with gabapentin.

CONCLUSION

These data provide no evidence of a beneficial effect of gabapentin on disease progression or symptoms in patients with ALS.

III. Electrophysiological studies of face processing in Williams syndrome

Williams Syndrome (WMS) is a genetically based disorder characterized by pronounced variability in performance across different domains of cognitive functioning. This study examined brain activity linked to face-processing abilities, which are typically spared in individuals with WMS. Subjects watched photographic pairs of upright or inverted faces and indicated if the second face matched or did not match the first face. Results from a previous study with normal adults showed dramatic differences in the timing and distribution of ERP effects linked to recognition of upright and inverted faces. In normal adults, upright faces elicited ERP differences to matched vs. mismatched faces at approximately 320 msec (N320) after the onset of the second stimulus. This "N320" effect was largest over anterior regions of the right hemisphere. In contrast, the mismatch/match effect for inverted faces consisted of a large positive component between 400 and 1000 msec (P500) that was largest over parietal regions and was symmetrical. In contrast to normal adults, WMS subjects showed an N320-mismatch effect for both upright and inverted faces. Additionally, the WMS subjects did not display the N320 right-hemisphere asymmetry observed in the normal adults. WMS subjects also displayed an abnormally small negativity at 100 msec (N100) and an abnormally large negativity at 200 msec (N200) to both upright and inverted faces. This ERP pattern was observed in all subjects with WMS but was not observed in the normal controls. These results may be linked to increased attention to faces in subjects with WMS and might be specific to the disorder. These results were consistent with our ERP studies of language processing in WMS, which suggested abnormal cerebral specialization for spared cognitive functions in individuals with WMS.

Visual attention to the periphery is enhanced in congenitally deaf individuals

We compared normally hearing individuals and congenitally deaf individuals as they monitored moving stimuli either in the periphery or in the center of the visual field. When participants monitored the peripheral visual field, greater recruitment (as measured by functional magnetic resonance imaging) of the motion-selective area MT/MST was observed in deaf than in hearing individuals, whereas the two groups were comparable when attending to the central visual field. This finding indicates an enhancement of visual attention to peripheral visual space in deaf individuals. Structural equation modeling was used to further characterize the nature of this plastic change in the deaf. The effective connectivity between MT/MST and the posterior parietal cortex was stronger in deaf than in hearing individuals during peripheral but not central attention. Thus, enhanced peripheral attention to moving stimuli in the deaf may be mediated by alterations of the connectivity between MT/MST and the parietal cortex, one of the primary centers for spatial representation and attention.

Word order effects in German sentences and German pseudo-word sentences

Summary: German belongs to those languages that allow a free permutation of subject, direct object and indirect object in verb final sentences. Five linear precedence (LP) principles have been postulated to describe preference patterns for the different word orders ( Uszkoreit, 1986 ). The present study tested if these rules are valid for meaningful German sentences only or also hold for pseudo-word sentences, i.e., if they are independent of semantic language aspects. Twelve students saw sentences in six different but legal word orders and in one illegal word order, either with normal German words or pronounceable pseudo-words. They had to answer a question focussing on the thematic role of one or more complements. In addition, they rated the acceptability of a subset of sentences in all experimental conditions. The canonical word order was processed fastest and processing times increased the more LP-principles were violated, both for normal and pseudo-word sentences. Moreover, acceptability ratings decreased monotonously with an increasing deviation of the sentences from its canonical word order, again irrespective of the stimulus material. The ungrammatical permutation received the lowest acceptability ruting. These results imply that the LP-principles describe syntactical preferences independent of meaning, at least in isolated sentences.

Sentence Reading: A Functional MRI Study at 4 Tesla

In this study, changes in blood oxygenation and volume were monitored while monolingual right-handed subjects read English sentences. Our results confirm the role of the left peri-sylvian cortex in language processing. Interestingly, individual subject analyses reveal a pattern of activation characterized by several small, limited patches rather than a few large, anatomically well-circumscribed centers. Between-subject analyses confirm a lateralized pattern of activation and reveal active classical language areas including Broca's area, Wernicke's area, and the angular gyms. In addition they point to areas only more recently considered as language-relevant including the anterior portion of the superior temporal sulcus. This area has not been reliably observed in imaging studies of isolated word processing. This raises the hypothesis that activation in this area is dependent on processes specific to sentence reading.

Identification, tissue-specific expression, and subcellular localization of the 80- and 71-kDa forms of myotonic dystrophy kinase protein

The protein product of the myotonic dystrophy (DM) gene is a putative serine-threonine protein kinase (DM kinase). Previous reports have characterized the DM gene product as various 50-62-kDa proteins. The predicted protein size from DM cDNA sequence is 69 kDa. We therefore expressed a full-length recombinant human DM kinase protein and compared its size and expression to heart, cardiac Purkinje fibers, and skeletal muscle from normal and DM subjects. Recombinantly expressed DM kinase and endogenous DM kinase in human heart, displayed two immunoreactive DM kinase proteins with apparent molecular sizes of 71 and 80 kDa, suggesting that these prior reports are incorrect. In cardiac Purkinje fibers the 71-kDa protein was the major form, and in skeletal muscle the 80-kDa protein was the major form. Immunostaining showed DM kinase localized to neuromuscular junctions in skeletal muscle and intercalated discs in heart and Purkinje fibers. DM subjects showed low abundance of DM kinase in heart and skeletal muscle, suggesting haplotype insufficiency as a potential mechanism for disease expression. These studies describe differential expression of two protein forms of DM kinase, which are localized to specialized cellular structures associated with impulse transmission.

Syntactically Based Sentence Processing Classes: Evidence from Event-Related Brain Potentials

Theoretical considerations and diverse empirical data from clinical, psycholinguistic, and developmental studies suggest that language comprehension processes are decomposable into separate subsystems, including distinct systems for semantic and grammatical processing. Here we report that event-related potentials (ERPs) to syntactically well-formed but semantically anomalous sentences produced a pattern of brain activity that is distinct in timing and distribution from the patterns elicited by syntactically deviant sentences, and further, that different types of syntactic deviance produced distinct ERP patterns.

Forty right-handed young adults read sentences presented at 2 words/sec while ERPs were recorded from over several positions between and within the hemispheres. Half of the sentences were semantically and grammatically acceptable and were controls for the remainder, which contained sentence medial words that violated (1) semantic expectations, (2) phrase structure rules, or (3) WH-movement constraints on Specificity and (4) Subjacency. As in prior research, the semantic anomalies produced a negative potential, N400, that was bilaterally distributed and was largest over posterior regions. The phrase structure violations enhanced the N125 response over anterior regions of the left hemisphere, and elicited a negative response (300-500 msec) over temporal and parietal regions of the left hemisphere. Violations of Specificity constraints produced a slow negative potential, evident by 125 msec, that was also largest over anterior regions of the left hemisphere. Violations of Subjacency constraints elicited a broadly and symmetrically distributed positivity that onset around 200 msec. The distinct timing and distribution of these effects provide biological support for theories that distinguish between these types of grammatical rules and constraints and more generally for the proposal that semantic and grammatical processes are distinct subsystems within the language faculty.

Isolated vitamin E deficiency in the absence of fat malabsorption--familial and sporadic cases: characterization and investigation of causes

We observed four young adults, including three siblings, with a progressive neurologic disorder that developed over the first two decades. Electrophysiologic studies revealed mildly delayed nerve conduction, decreased amplitudes of sensory action potentials, and sensory delay in the posterior columns. Known causes of similar neurologic disorders were excluded. Although vitamin E deficiency was well documented, intestinal absorption and plasma lipoprotein transport of vitamin E were normal. Incubation studies in vitro failed to identify a plasma factor causing destruction of circulating vitamin E. There was no clinical or laboratory evidence of steatorrhea caused by gastrointestinal, hepatic, or pancreatic disease. Plasma lipoproteins, apolipoprotein B, and adipose tissue fatty acid composition were normal. Oral vitamin E therapy restored serum levels to normal and caused neurologic improvement in two patients. We postulate that an inherited defect in hepatocyte secretion of vitamin E into lipoproteins may account for this disorder, which occurs in sporadic cases as well as in siblings.

Friedreich's disease: V. Variant form with vitamin E deficiency and normal fat absorption

A 30-year-old woman was thought to have Friedreich's disease because of progressive ataxia, dysarthria, and titubation from age 3 years. Her diet was normal, and there were neither symptoms nor laboratory evidence of liver disease or fat malabsorption. Serum vitamin E content and the ratio of serum vitamin E to total serum lipid were very low, but serum vitamin A, cholylglycine, and lipid levels were normal, as was an oral vitamin E tolerance test. Muscle biopsy showed the lysosomal inclusions of vitamin E deficiency. Mitochondria had normal oxidative phosphorylation using polarographic assays. The cause of her vitamin E deficiency was unknown.

Event-related brain potentials are different in individuals at high and low risk for developing alcoholism

Event-related brain potentials (ERPs) from normal drinkers with and without a family history of alcoholism were compared. Three separate groups of 10 subjects each (5 with and 5 without a family history of alcoholism) ingested either a placebo or ethanol at 0.56 or 0.94 g/kg. In each comparison, ERP components elicited in conjunction with subjects' decisions about task-relevant stimuli were of significantly reduced amplitude in individuals with a family history of alcoholism. Additionally, both the latency of the positive component and reaction times to correctly detected targets were significantly later in individuals with a positive history of alcoholism than in those without such a history. These group differences were apparent both with and without a challenge of alcohol. The data suggest that brain functions are different in individuals at high and low risk for the development of alcoholism (i.e., those with and without a family history of alcoholism, respectively).

Recognition and surprise alter the human visual evoked response

Event-related brain potentials (ERPs) to colored slides contained a late positive component that was significantly enhanced when adults recognized the person, place, or painting in the photograph. Additionally, two late components change in amplitude, corresponding to the amount of surprise reported. Because subjects received no instructions to differentiate among the slides, these changes in brain potentials reflect natural classifications made according to their perceptions and evaluations of the pictorial material. This may be a useful paradigm with which to assess perception, memory, and orienting capacities in populations such as infants who cannot follow verbal instructions.

Studies on the retina and the pigment epithelium in hereditary canine ceroid lipofuscinosis. III. Morphologic abnormalities in retinal neurons and retinal pigmented epithelial cells

Studies of the retina in 6- and 22-month-old English setters with progressive blindness, ataxia, and muscle weakness demonstrated a marked accumulation of abnormal cytosomes within neurons and retinal pigmented epithelial cells. Ganglion cells contained abundant cytosomes with evenly spaced stacks of membranes; bipolar and amacrine cell cytosomes consisted of dense, amorphous material with closely spaced configurations of light and dark lines; cytosomes within photoreceptor cells contained faintly staining curved profiles. All three cytosomes resembled those previously reported in brain neurons of CCL dogs. In retinal pigmented epithelial cells, there were prominent accumulations of lamellar fragments, either free in the cytoplasm or incorporated into melanin granules. These retinal abnormalities are likely to be related to deficiences of peroxidase and defects of lipid peroxidation. The pathologic and biochemical changes seen in these dogs are similar in many respects to those reported in human patients with Batten disease. As such, these dogs provide a convenient model for the study disease mechanisms and for therapeutic approaches to blindness in Batten disease.

Detection of canine Batten disease with the EEG

Although it has been suggested that EEG changes appear early in the course of human Batten disease, these observations have been made only after the onset of clinical abnormalities and without immediate pathological correlation. In this brief report we have been able to document for the first time, abnormal EEGs in a strain of dogs proposed as a model for Batten disease. The degree of abnormality in the canine EEG correlated with the degree of clinical involvement and with the presence of pathological inclusions, resembling those seen in human Batten disease. In younger dogs, abnormal EEGs were obtained even before clinical manifestations of the disease. The large amplitude discharges reported with photic stimulation in children with the late infantile form of Batten disease were not elicited in the dog model. However, this dog strain is a model for the juvenile rather than the late infantile form although similarities between dogs and both forms of human Batten disease were seen. It is proposed that the EEG is both a method for early detection of this disease as well as a tool ot measure the degree of involvement. This information may be of use in relation to future therapeutic trials.