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1.
Cereb Cortex ; 34(4)2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38566510

RESUMEN

Statistical learning (SL) is the ability to detect and learn regularities from input and is foundational to language acquisition. Despite the dominant role of SL as a theoretical construct for language development, there is a lack of direct evidence supporting the shared neural substrates underlying language processing and SL. It is also not clear whether the similarities, if any, are related to linguistic processing, or statistical regularities in general. The current study tests whether the brain regions involved in natural language processing are similarly recruited during auditory, linguistic SL. Twenty-two adults performed an auditory linguistic SL task, an auditory nonlinguistic SL task, and a passive story listening task as their neural activation was monitored. Within the language network, the left posterior temporal gyrus showed sensitivity to embedded speech regularities during auditory, linguistic SL, but not auditory, nonlinguistic SL. Using a multivoxel pattern similarity analysis, we uncovered similarities between the neural representation of auditory, linguistic SL, and language processing within the left posterior temporal gyrus. No other brain regions showed similarities between linguistic SL and language comprehension, suggesting that a shared neurocomputational process for auditory SL and natural language processing within the left posterior temporal gyrus is specific to linguistic stimuli.


Asunto(s)
Aprendizaje , Percepción del Habla , Adulto , Humanos , Lenguaje , Lingüística , Desarrollo del Lenguaje , Encéfalo , Percepción del Habla/fisiología , Mapeo Encefálico , Imagen por Resonancia Magnética
2.
medRxiv ; 2024 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-38293201

RESUMEN

Post-infection inflammatory syndromes have been increasingly recognized as a cause of host damage in a variety of infectious diseases including tuberculosis, bacterial meningitis, and COVID-19. Recently, a post-infectious inflammatory response syndrome (PIIRS) was described in non-HIV-infected cryptococcal fungal meningoencephalitis (CM) as a major cause of mortality. Inflammatory syndromes are particularly severe in neurological infections due to the skull's rigid structure which limits unchecked tissue expansion from inflammatory-induced edema. In the present studies, neurologic transcriptional pathway analysis utilizing a murine PIIRS model demonstrated a predominance of Janus kinase/signal transducer and activator of transcription (JAK/STAT) activation. JAK/STAT inhibitor treatment resulted in improvements in CNS damage markers, reductions in intrathecal CD44hiCD62lo CD4+ effector CD4+ T-cells and MHC II+ inflammatory myeloid cells, and weight gains in mice, the latter after treatment with antifungals. Based on these data, pathway-driven steroid-sparing human treatment for steroid-refractory PIIRS was initiated using short courses of the JAK/STAT inhibitor ruxolitinib. These were well tolerated and reduced activated HLA-DR+ CD4+ and CD8+ cells and inflammatory monocytes as well as improved brain imaging. Together, these findings support the role of JAK/STAT in PIIRS as well as further study of JAK/STAT inhibitors as potential adjunctive therapy for PIRS and other neural inflammatory syndromes.

3.
Neuroimage ; 285: 120489, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38065277

RESUMEN

Important recent advances in the cognitive neuroscience of language have been made using functional localizers to demarcate language-selective regions in individual brains. Although single-subject localizers offer insights that are unavailable in classic group analyses, they require additional scan time that imposes costs on investigators and participants. In particular, the unique practical challenges of scanning children and other special populations has led to less adoption of localizers for neuroimaging research with these theoretically and clinically important groups. Here, we examined how measurements of the spatial extent and functional response profiles of language regions are affected by the duration of an auditory language localizer. We compared how parametrically smaller amounts of data collected from one scanning session affected (i) consistency of group-level whole-brain parcellations, (ii) functional selectivity of subject-level activation in individually defined functional regions of interest (fROIs), (iii) sensitivity and specificity of subject-level whole-brain and fROI activation, and (iv) test-retest reliability of subject-level whole-brain and fROI activation. For many of these metrics, the localizer duration could be reduced by 50-75% while preserving the stability and reliability of both the spatial extent and functional response profiles of language areas. These results indicate that, for most measures relevant to cognitive neuroimaging studies, the brain's language network can be localized just as effectively with 3.5 min of scan time as it can with 12 min. Minimizing the time required to reliably localize the brain's language network allows more effective localizer use in situations where each minute of scan time is particularly precious.


Asunto(s)
Mapeo Encefálico , Imagen por Resonancia Magnética , Niño , Humanos , Mapeo Encefálico/métodos , Reproducibilidad de los Resultados , Imagen por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Lenguaje
4.
J Clin Immunol ; 43(8): 2146-2155, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37814084

RESUMEN

PURPOSE: Non-HIV cryptococcal meningoencephalitis (CM) in previously healthy individuals is often complicated by a post-infectious inflammatory response syndrome (c-PIIRS) characterized by neurologic deterioration after appropriate antifungal therapy with sterilization of CSF fungal cultures. c-PIIRS results from an excessive inflammatory response to fungal antigens released during fungal lysis, mediated by IFN-γ, IL-6, and activated T-helper cells, leading to immune-mediated host damage that responds to pulse-corticosteroid taper therapy (PCT). Typically, oral steroids may take up to a year to taper, and occasionally, patients will be refractory to steroid therapy or may demonstrate high-risk lesions such as those involving intracranial arteries. Also, patients can have problematic side effects from prolonged corticosteroids. Hence, appropriate adjunctive agents are needed to reduce corticosteroid doses in the treatment of c-PIIRS. Due to a possible role of IL-6 in pathogenesis, IL-6 receptor blockade by tocilizumab may be useful in the treatment of c-PIIRS. METHODS: Two previously healthy patients with non-HIV cPIIRS were seen at the NIH. Due to concerns for intracranial vascular rupture in an area of inflammation (Patient 1) and intractable symptoms on high-dose oral corticosteroids (Patient 2) with evidence of persistent CSF inflammation, patients were treated with 4-8 mg/kg tocilizumab every 2 weeks while maintained on a constant dose of prednisone. RESULTS: Two patients exhibited rapid immunological improvement following treatment with tocilizumab. Patient 1 remained vascularly stable, and Patient 2 had near resolution of headaches with improvement in mental status as evidenced by improved MOCA score. The two had improved CSF inflammatory parameters and no significant side effects. Both CSF cultures remained negative throughout treatment. CONCLUSIONS: Tocilizumab may be a safe adjunctive treatment for CM-related PIIRS suggesting further study.


Asunto(s)
Cryptococcus , Meningitis Criptocócica , Meningoencefalitis , Humanos , Meningitis Criptocócica/diagnóstico , Meningitis Criptocócica/tratamiento farmacológico , Interleucina-6 , Inflamación , Corticoesteroides/uso terapéutico , Meningoencefalitis/tratamiento farmacológico
5.
J Neurosurg Case Lessons ; 5(13)2023 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-37014023

RESUMEN

BACKGROUND: Apraxia of speech is a disorder of speech-motor planning in which articulation is effortful and error-prone despite normal strength of the articulators. Phonological alexia and agraphia are disorders of reading and writing disproportionately affecting unfamiliar words. These disorders are almost always accompanied by aphasia. OBSERVATIONS: A 36-year-old woman underwent resection of a grade IV astrocytoma based in the left middle precentral gyrus, including a cortical site associated with speech arrest during electrocortical stimulation mapping. Following surgery, she exhibited moderate apraxia of speech and difficulty with reading and spelling, both of which improved but persisted 6 months after surgery. A battery of speech and language assessments was administered, revealing preserved comprehension, naming, cognition, and orofacial praxis, with largely isolated deficits in speech-motor planning and the spelling and reading of nonwords. LESSONS: This case describes a specific constellation of speech-motor and written language symptoms-apraxia of speech, phonological agraphia, and phonological alexia in the absence of aphasia-which the authors theorize may be attributable to disruption of a single process of "motor-phonological sequencing." The middle precentral gyrus may play an important role in the planning of motorically complex phonological sequences for production, independent of output modality.

6.
J Neurosci ; 42(45): 8416-8426, 2022 11 09.
Artículo en Inglés | MEDLINE | ID: mdl-36351829

RESUMEN

Classical models have traditionally focused on the left posterior inferior frontal gyrus (Broca's area) as a key region for motor planning of speech production. However, converging evidence suggests that it is not critical for either speech motor planning or execution. Alternative cortical areas supporting high-level speech motor planning have yet to be defined. In this review, we focus on the precentral gyrus, whose role in speech production is often thought to be limited to lower-level articulatory muscle control. In particular, we highlight neurosurgical investigations that have shed light on a cortical region anatomically located near the midpoint of the precentral gyrus, hence called the middle precentral gyrus (midPrCG). The midPrCG is functionally located between dorsal hand and ventral orofacial cortical representations and exhibits unique sensorimotor and multisensory functions relevant for speech processing. This includes motor control of the larynx, auditory processing, as well as a role in reading and writing. Furthermore, direct electrical stimulation of midPrCG can evoke complex movements, such as vocalization, and selective injury can cause deficits in verbal fluency, such as pure apraxia of speech. Based on these findings, we propose that midPrCG is essential to phonological-motoric aspects of speech production, especially syllabic-level speech sequencing, a role traditionally ascribed to Broca's area. The midPrCG is a cortical brain area that should be included in contemporary models of speech production with a unique role in speech motor planning and execution.


Asunto(s)
Corteza Motora , Habla , Habla/fisiología , Mapeo Encefálico , Lóbulo Frontal/fisiología , Área de Broca , Encéfalo , Imagen por Resonancia Magnética
7.
Sci Rep ; 11(1): 3673, 2021 02 11.
Artículo en Inglés | MEDLINE | ID: mdl-33574462

RESUMEN

The morbidity and mortality of cryptococcal meningoencephalitis (CM) in previously healthy, HIV-negative individuals is increasingly recognized. We administered a healthcare associated quality of life (QOL) survey to the largest longitudinally followed cohort of these patients in the United States. We identified moderate or severe self-reported impairment in at least one QOL domain in 61% of subjects at least one year following diagnosis. Self-reported cognitive impairment was noted in 52% and sleep disturbance was noted in 55%. This is the first comprehensive study of cross-sectional long-term QOL in previously healthy patients following cryptococcal infection.


Asunto(s)
Cryptococcus neoformans/patogenicidad , Infecciones por VIH/epidemiología , VIH/patogenicidad , Meningitis Criptocócica/epidemiología , Adulto , Estudios de Cohortes , Femenino , Infecciones por VIH/complicaciones , Infecciones por VIH/virología , Estado de Salud , Humanos , Masculino , Meningitis Criptocócica/etnología , Meningitis Criptocócica/microbiología , Meningitis Criptocócica/virología , Persona de Mediana Edad , Calidad de Vida
8.
Clin Infect Dis ; 73(9): e2789-e2798, 2021 11 02.
Artículo en Inglés | MEDLINE | ID: mdl-33383587

RESUMEN

BACKGROUND: Cryptococcal meningoencephalitis (CM) is a major cause of mortality in immunosuppressed patients and previously healthy individuals. In the latter, a post-infectious inflammatory response syndrome (PIIRS) is associated with poor clinical response despite antifungal therapy and negative cerebrospinal fluid (CSF) cultures. Data on effective treatment are limited. METHODS: Between March 2015 and March 2020, 15 consecutive previously healthy patients with CM and PIIRS were treated with adjunctive pulse corticosteroid taper therapy (PCT) consisting of intravenous methylprednisolone 1 gm daily for 1 week followed by oral prednisone 1 mg/kg/day, tapered based on clinical and radiological response plus oral fluconazole. Montreal cognitive assessments (MOCA), Karnofsky performance scores, magnetic resonance imaging (MRI) brain scanning, ophthalmic and audiologic exams, and CSF parameters including cellular and soluble immune responses were compared at PIIRS diagnosis and after methylprednisolone completion. RESULTS: The median time from antifungal treatment to steroid initiation was 6 weeks. The most common symptoms at PIIRS diagnosis were altered mental status and vision changes. All patients demonstrated significant improvements in MOCA and Karnofsky scores at 1 month (P < .0003), which was accompanied by improvements in CSF glucose, white blood cell (WBC) count, protein, cellular and soluble inflammatory markers 1 week after receiving corticosteroids (CS) (P < .003). All patients with papilledema and visual field deficits also exhibited improvement (P < .0005). Five out of 7 patients who underwent audiological testing demonstrated hearing improvement. Brain MRI showed significant improvement of radiological findings (P = .001). CSF cultures remained negative. CONCLUSIONS: PCT in this small cohort of PIIRS was associated with improvements in CM-related complications with minimal toxicity in the acute setting.


Asunto(s)
Cryptococcus , Meningitis Criptocócica , Meningoencefalitis , Corticoesteroides/uso terapéutico , Antifúngicos/uso terapéutico , Fluconazol , Humanos , Meningitis Criptocócica/tratamiento farmacológico , Meningoencefalitis/tratamiento farmacológico
9.
Brain Lang ; 209: 104840, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32738502

RESUMEN

Sensorimotor adaptation-enduring changes to motor commands due to sensory feedback-allows speakers to match their articulations to intended speech acoustics. How the brain integrates auditory feedback to modify speech motor commands and what limits the degree of these modifications remain unknown. Here, we investigated the role of speech motor cortex in modifying stored speech motor plans. In a within-subjects design, participants underwent separate sessions of sham and anodal transcranial direct current stimulation (tDCS) over speech motor cortex while speaking and receiving altered auditory feedback of the first formant. Anodal tDCS increased the rate of sensorimotor adaptation for feedback perturbation. Computational modeling of our results using the Directions Into Velocities of Articulators (DIVA) framework of speech production suggested that tDCS primarily affected behavior by increasing the feedforward learning rate. This study demonstrates how focal noninvasive neurostimulation can enhance the integration of auditory feedback into speech motor plans.


Asunto(s)
Retroalimentación Sensorial/fisiología , Aprendizaje/fisiología , Corteza Motora/fisiología , Desempeño Psicomotor/fisiología , Habla/fisiología , Estimulación Transcraneal de Corriente Directa , Adulto , Femenino , Humanos , Masculino , Modelación Específica para el Paciente , Acústica del Lenguaje , Adulto Joven
10.
Neuroimage ; 202: 116096, 2019 11 15.
Artículo en Inglés | MEDLINE | ID: mdl-31415882

RESUMEN

Phonological working memory is the capacity to briefly maintain and recall representations of sounds important for speech and language and is believed to be critical for language and reading acquisition. Whether phonological working memory is supported by fronto-parietal brain regions associated with short-term memory storage or perisylvian brain structures implicated in speech perception and production is unclear, perhaps due to variability in stimuli, task demands, and individuals. We used fMRI to assess neurophysiological responses while individuals performed two tasks with closely matched stimuli but divergent task demands-nonword repetition and nonword discrimination-at two levels of phonological working memory load. Using analyses designed to address intersubject variability, we found significant neural responses to the critical contrast of high vs. low phonological working memory load in both tasks in a set of regions closely resembling those involved in speech perception and production. Moreover, within those regions, the voxel-wise patterns of load-related activation were highly correlated between the two tasks. These results suggest that brain regions in the temporal and frontal lobes encapsulate the core neurocomputational components of phonological working memory; an architecture that becomes increasingly evident as neural responses are examined in successively finer-grained detail in individual participants.


Asunto(s)
Corteza Cerebral/anatomía & histología , Corteza Cerebral/fisiología , Memoria a Corto Plazo/fisiología , Adulto , Mapeo Encefálico/métodos , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética/métodos , Masculino , Percepción del Habla/fisiología , Adulto Joven
11.
Front Psychol ; 10: 2995, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-32038381

RESUMEN

Sensorimotor adaptation experiments are commonly used to examine motor learning behavior and to uncover information about the underlying control mechanisms of many motor behaviors, including speech production. In the speech and voice domains, aspects of the acoustic signal are shifted/perturbed over time via auditory feedback manipulations. In response, speakers alter their production in the opposite direction of the shift so that their perceived production is closer to what they intended. This process relies on a combination of feedback and feedforward control mechanisms that are difficult to disentangle. The current study describes and tests a simple 3-parameter mathematical model that quantifies the relative contribution of feedback and feedforward control mechanisms to sensorimotor adaptation. The model is a simplified version of the DIVA model, an adaptive neural network model of speech motor control. The three fitting parameters of SimpleDIVA are associated with the three key subsystems involved in speech motor control, namely auditory feedback control, somatosensory feedback control, and feedforward control. The model is tested through computer simulations that identify optimal model fits to six existing sensorimotor adaptation datasets. We show its utility in (1) interpreting the results of adaptation experiments involving the first and second formant frequencies as well as fundamental frequency; (2) assessing the effects of masking noise in adaptation paradigms; (3) fitting more than one perturbation dimension simultaneously; (4) examining sensorimotor adaptation at different timepoints in the production signal; and (5) quantitatively predicting responses in one experiment using parameters derived from another experiment. The model simulations produce excellent fits to real data across different types of perturbations and experimental paradigms (mean correlation between data and model fits across all six studies = 0.95 ± 0.02). The model parameters provide a mechanistic explanation for the behavioral responses to the adaptation paradigm that are not readily available from the behavioral responses alone. Overall, SimpleDIVA offers new insights into speech and voice motor control and has the potential to inform future directions of speech rehabilitation research in disordered populations. Simulation software, including an easy-to-use graphical user interface, is publicly available to facilitate the use of the model in future studies.

12.
J Consult Clin Psychol ; 86(11): 931-945, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30335425

RESUMEN

OBJECTIVE: Debate ensues regarding female-specific risk and strength factors among adolescent offenders. Using meta-analysis, we examined whether risk and strength factors predicted recidivism differentially between male and female youth. METHOD: Database searches identified 22 studies, representing 50,601 justice-involved youth (11,952 females and 38,649 males) and a total of 584 effect sizes. RESULTS: For the global risk domains, there is some evidence for gender neutrality (i.e., risk factors predict to the same degree for both males and females) among most domains (e.g., antisocial peer relations, problematic family circumstances and parenting, substance abuse, antisocial personality/behavior, and antisocial attitudes/orientation). Although the global domains of mental health and child abuse were not significantly predictive for either gender, the global child abuse results trended in favor of predicting recidivism for females. When global risk domains were broken into indicators, some evidence for gender differences emerged (e.g., chronic alcohol use and family substance abuse predicted more strongly for females than for males). Last, gender comparisons among the global strength domains revealed that prosocial peers and the absence of substance abuse predicted success (i.e., no recidivism) for both genders, though a stronger effect emerged for males. In addition, education/employment strengths predicted success for males, whereas prosocial values predicted success for females. Limitations such as the lack of studies that defined constructs from the female experience, and the small number of primary studies are discussed. CONCLUSIONS: Advancing the future of gender informed practice with justice-involved youth will require careful consideration of both gender similarities and differences. (PsycINFO Database Record (c) 2018 APA, all rights reserved).


Asunto(s)
Trastorno de Personalidad Antisocial/psicología , Trastorno de Personalidad Antisocial/rehabilitación , Delincuencia Juvenil/psicología , Delincuencia Juvenil/rehabilitación , Responsabilidad Parental/psicología , Adolescente , Niño , Maltrato a los Niños/psicología , Maltrato a los Niños/rehabilitación , Relaciones Familiares , Femenino , Identidad de Género , Humanos , Masculino , Salud Mental , Grupo Paritario , Pronóstico , Reincidencia , Factores de Riesgo , Justicia Social , Trastornos Relacionados con Sustancias/psicología , Trastornos Relacionados con Sustancias/rehabilitación
13.
Cogn Neurosci ; 8(3): 167-176, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-27386919

RESUMEN

A set of brain regions in the frontal, temporal, and parietal lobes supports high-level linguistic processing. These regions can be reliably identified in individual subjects using fMRI, by contrasting neural responses to meaningful and structured language stimuli vs. stimuli matched for low-level properties but lacking meaning and/or structure. We here present a novel version of a language 'localizer,' which should be suitable for diverse populations including children and/or clinical populations who may have difficulty with reading or cognitively demanding tasks. In particular, we contrast responses to auditorily presented excerpts from engaging interviews or stories, and acoustically degraded versions of these materials. This language localizer is appealing because it uses (a) naturalistic and engaging linguistic materials, (b) auditory presentation,


Asunto(s)
Mapeo Encefálico/métodos , Corteza Cerebral/fisiología , Lenguaje , Imagen por Resonancia Magnética/métodos , Percepción del Habla/fisiología , Adolescente , Adulto , Corteza Cerebral/diagnóstico por imagen , Femenino , Humanos , Masculino , Adulto Joven
14.
Proc Natl Acad Sci U S A ; 113(41): E6256-E6262, 2016 10 11.
Artículo en Inglés | MEDLINE | ID: mdl-27671642

RESUMEN

The neural processes that underlie your ability to read and understand this sentence are unknown. Sentence comprehension occurs very rapidly, and can only be understood at a mechanistic level by discovering the precise sequence of underlying computational and neural events. However, we have no continuous and online neural measure of sentence processing with high spatial and temporal resolution. Here we report just such a measure: intracranial recordings from the surface of the human brain show that neural activity, indexed by γ-power, increases monotonically over the course of a sentence as people read it. This steady increase in activity is absent when people read and remember nonword-lists, despite the higher cognitive demand entailed, ruling out accounts in terms of generic attention, working memory, and cognitive load. Response increases are lower for sentence structure without meaning ("Jabberwocky" sentences) and word meaning without sentence structure (word-lists), showing that this effect is not explained by responses to syntax or word meaning alone. Instead, the full effect is found only for sentences, implicating compositional processes of sentence understanding, a striking and unique feature of human language not shared with animal communication systems. This work opens up new avenues for investigating the sequence of neural events that underlie the construction of linguistic meaning.


Asunto(s)
Encéfalo/fisiología , Semántica , Adolescente , Adulto , Corteza Cerebral/fisiología , Electrodos , Femenino , Humanos , Adulto Joven
15.
Body Image ; 17: 171-4, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27085112

RESUMEN

Body image activists have proposed adding disclaimer labels to digitally altered media as a way to promote positive body image. Another approach advocated by activists is to alter advertisements through subvertising (adding social commentary to the image to undermine the message of the advertisement). We examined if body image could be enhanced by attaching Photoshop disclaimers or subvertising to thin-ideal media images of swimsuit models. In Study 1 (N=1268), adult women exposed to disclaimers or subvertising did not report higher body state satisfaction or lower drive for thinness than women exposed to unaltered images. In Study 2 (N=820), adult women who were exposed to disclaimers or subvertising did not report higher state body satisfaction or lower state social appearance comparisons than women exposed to unaltered images or to no images. These results raise questions about the effectiveness of disclaimers and subvertising for promoting body satisfaction.


Asunto(s)
Imagen Corporal/psicología , Retroalimentación , Control Interno-Externo , Medios de Comunicación de Masas , Delgadez/psicología , Adolescente , Adulto , Publicidad , Anciano , Femenino , Humanos , Peso Corporal Ideal , Persona de Mediana Edad , Distorsión de la Percepción , Satisfacción Personal , Revelación de la Verdad , Adulto Joven
16.
Brain Res ; 1313: 162-71, 2010 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-20006592

RESUMEN

Both smoking and nicotine can facilitate cognitive efficiency in humans, however the exact mechanism underlying this improvement in cognitive performance is unclear. Nicotine-related improvements in visual task performance may stem from facilitation of the identification and encoding of rare deviant stimuli at early sensory levels. Visual processes at these early levels are thought to be indexed by the visual mismatch negativity (vMMN), an event-related potential (ERP) measure of pre-conscious deviant detection. In order to contribute to our understanding of the neural mechanisms underlying nicotinic modulated cognition, the current study investigated the acute effects of nicotine on vMMN in a non-smoking sample. Twenty-seven volunteers (7 males, 20 females) were treated with nicotine gum (6 mg) in a double-blind randomized, placebo-controlled repeated measures design. ERPs (vMMN; visual N100 and P200) and motor indices of performance were extracted from an intermodal task, requiring participants to attend selectively to auditory targets presented within concurrent, non-overlapping oddball sequences of visual standard and deviant stimuli. Behavioural performance was unaffected by nicotine, however nicotine was found to enhance vMMN and P200 amplitude. The findings are discussed in relation to attentional and neurobiological theories of nicotine dependence and of cognition in general.


Asunto(s)
Atención/efectos de los fármacos , Encéfalo/efectos de los fármacos , Potenciales Evocados Visuales/efectos de los fármacos , Nicotina/farmacología , Agonistas Nicotínicos/farmacología , Percepción Visual/efectos de los fármacos , Estimulación Acústica , Adolescente , Adulto , Atención/fisiología , Encéfalo/fisiología , Goma de Mascar , Método Doble Ciego , Electroencefalografía , Femenino , Humanos , Masculino , Pruebas Neuropsicológicas , Nicotina/administración & dosificación , Nicotina/efectos adversos , Agonistas Nicotínicos/administración & dosificación , Agonistas Nicotínicos/efectos adversos , Factores de Tiempo , Percepción Visual/fisiología , Adulto Joven
17.
Proc Natl Acad Sci U S A ; 106(25): 10081-5, 2009 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-19506255

RESUMEN

In this experimental and theoretical study, we investigate the slithering of snakes on flat surfaces. Previous studies of slithering have rested on the assumption that snakes slither by pushing laterally against rocks and branches. In this study, we develop a theoretical model for slithering locomotion by observing snake motion kinematics and experimentally measuring the friction coefficients of snakeskin. Our predictions of body speed show good agreement with observations, demonstrating that snake propulsion on flat ground, and possibly in general, relies critically on the frictional anisotropy of their scales. We have also highlighted the importance of weight distribution in lateral undulation, previously difficult to visualize and hence assumed uniform. The ability to redistribute weight, clearly of importance when appendages are airborne in limbed locomotion, has a much broader generality, as shown by its role in improving limbless locomotion.


Asunto(s)
Colubridae/fisiología , Locomoción , Modelos Biológicos , Animales , Colubridae/anatomía & histología
18.
Clin EEG Neurosci ; 40(1): 11-20, 2009 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-19278128

RESUMEN

Research into the effects of nicotine and smoking on cognition has largely confirmed the subjective reports of smoking in smokers on mental functions, showing smoking abstinence to disrupt and smoking/nicotine to restore cognitive functioning. Evidence of performance improvements in nonsmokers has provided partial support for the absolute effects of nicotine on cognitive processes, which are independent of withdrawal relief, but the mechanisms underlying its pro-cognitive properties still remain elusive. The attentional facilitation frequently reported with smoking/nicotine may be indirectly related to its diffuse arousal-enhancing actions, as evidenced by electroencephalographic (EEG) fast frequency power increments, or it may reflect nicotine's direct modulating effects on specific neural processes governing stimulus encoding, selection and rejection. Event-related potential (ERP) components extracted during the performance of cognitive tasks have proven to be sensitive to early pre-attentive and later attention-dependent processes that are not otherwise reflected in behavioral probes. To date, the majority of ERP studies have been conducted with smokers using passive non-task paradigms or relatively non-demanding "oddball" tasks. This paper will emphasize our recent ERP investigations with acute nicotine polacrilex (6 mg) administered to nonsmokers, and with a battery of ERP and behavioral performance paradigms focusing on intra- and inter-modal selective attention and distraction processes. These ERP findings of nicotine-augmented early attentional processing add support to the contention that nicotine may be be used by smokers as a "pharmacological tool" for tuning cognitive functions relating to the automatic and controlled aspects of sensory input detection and selection.


Asunto(s)
Atención/efectos de los fármacos , Encéfalo/efectos de los fármacos , Encéfalo/fisiología , Nicotina/análogos & derivados , Ácidos Polimetacrílicos/administración & dosificación , Polivinilos/administración & dosificación , Percepción Auditiva/efectos de los fármacos , Percepción Auditiva/fisiología , Estimulantes del Sistema Nervioso Central/administración & dosificación , Electroencefalografía , Potenciales Evocados , Femenino , Humanos , Masculino , Nicotina/administración & dosificación , Tiempo de Reacción/efectos de los fármacos , Análisis y Desempeño de Tareas , Dispositivos para Dejar de Fumar Tabaco , Percepción Visual/efectos de los fármacos , Percepción Visual/fisiología , Adulto Joven
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