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1.
Neuroscience ; 493: 69-80, 2022 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-35490969

RESUMO

The medial nucleus of the amygdala (MeA) is known to regulate social behavior. This brain area is functionally positioned in a crossroads between sensory information processing and behavioral modulation. On the one hand, it receives direct chemosensory input from the accessory olfactory bulb. On the other hand, it orchestrates various behavioral outputs via brain-wide projections under the regulation of multiple neuromodulatory systems. Previously, we showed that adult male Sprague Dawley (SD) rats and C57BL/6J mice, the most widely used rodent models in neuroscience research, differ in their dynamics of motivation to interact with a novel same-sex conspecific and that this difference correlates with the level of c-Fos expression in the MeA. Here we used chronically implanted electrodes to compare rhythmic local field potential signals recorded from these animals during free and restricted social interactions. We found a significant induction of rhythmicity in the theta (4-12 Hz) and gamma (30-80 Hz) bands during both free and restricted social interaction in both rats and mice. However, the induction of gamma rhythmicity, thought to reflect activity of local neuronal networks, was significantly higher in rats than mice. Nevertheless, in contrast to rats, mice exhibited induction of rhythmicity, in both the theta and gamma bands, in synchrony with investigation of social, but not object stimuli. These results suggest that during interaction with a novel same-sex conspecific, the MeA of C57BL/6J mice is mostly involved in sensory information processing while in SD rats it is mainly active in modulating the social motivation state of the animal.


Assuntos
Tonsila do Cerebelo , Interação Social , Tonsila do Cerebelo/metabolismo , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Periodicidade , Ratos , Ratos Sprague-Dawley
2.
Sensors (Basel) ; 22(9)2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35590849

RESUMO

In this work, an adaptive generalized cross-correlation (AGCC) method is proposed that focuses on the problem of the conventional cross-correlation method not effectively realizing the time delay estimation of signals with strong periodicity. With the proposed method, the periodicity of signals is judged and the center frequencies of the strongly periodical components are determined through the spectral analysis of the input signals. Band-stop filters that are used to suppress the strongly periodical components are designed and the mutual power spectral density of the input signals that is processed by the band-stop filters is calculated. Then, the cross-correlation function that is processed is the inverse Fourier transform of the mutual power spectral density. Finally, the time delay is estimated by seeking the peak position of the processed cross-correlation function. Simulation experiments and practical velocity measurement experiments were carried out to verify the effectiveness of the proposed AGCC method. The experimental results showed that the new AGCC method could effectively realize the time delay estimation of signals with strong periodicity. In the simulation experiments, the new method could realize the effective time delay estimation of signals with strong periodicity when the energy ratio of the strongly periodical component to the aperiodic component was under 150. Meanwhile, the cross-correlation method and other generalized cross-correlation methods fail in time delay estimation when the energy ratio is higher than 30. In the practical experiments, the velocity measurement of slug flow with strong periodicity was implemented in small channels with inner diameters of 2.0 mm, 2.5 mm and 3.0 mm. With the proposed method, the relative errors of the velocity measurement were less than 4.50%.


Assuntos
Periodicidade , Velocidade do Fluxo Sanguíneo , Simulação por Computador , Análise de Fourier , Ultrassonografia
3.
Elife ; 112022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35451957

RESUMO

The cerebellum is hypothesized to represent timing information important for organizing salient motor events during periodically performed discontinuous movements. To provide functional evidence validating this idea, we measured and manipulated Purkinje cell (PC) activity in the lateral cerebellum of mice trained to volitionally perform periodic bouts of licking for regularly allocated water rewards. Overall, PC simple spiking modulated during task performance, mapping phasic tongue protrusions and retractions, as well as ramping prior to both lick-bout initiation and termination, two important motor events delimiting movement cycles. The ramping onset occurred earlier for the initiation of uncued exploratory licking that anticipated water availability relative to licking that was reactive to water allocation, suggesting that the cerebellum is engaged differently depending on the movement context. In a subpopulation of PCs, climbing-fiber-evoked responses also increased during lick-bout initiation, but not termination, highlighting differences in how cerebellar input pathways represent task-related information. Optogenetic perturbation of PC activity disrupted the behavior by degrading lick-bout rhythmicity in addition to initiating and terminating licking bouts confirming a causative role in movement organization. Together, these results substantiate that the cerebellum contributes to the initiation and timing of repeated motor actions.


Assuntos
Cerebelo , Células de Purkinje , Animais , Cerebelo/fisiologia , Camundongos , Movimento/fisiologia , Periodicidade , Células de Purkinje/fisiologia , Água
4.
Sci Rep ; 12(1): 6688, 2022 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-35461325

RESUMO

Attention has been found to sample visual information periodically, in a wide range of frequencies below 20 Hz. This periodicity may be supported by brain oscillations at corresponding frequencies. We propose that part of the discrepancy in periodic frequencies observed in the literature is due to differences in attentional demands, resulting from heterogeneity in tasks performed. To test this hypothesis, we used visual search and manipulated task complexity, i.e., target discriminability (high, medium, low) and number of distractors (set size), while electro-encephalography was simultaneously recorded. We replicated previous results showing that the phase of pre-stimulus low-frequency oscillations predicts search performance. Crucially, such effects were observed at increasing frequencies within the theta-alpha range (6-18 Hz) for decreasing target discriminability. In medium and low discriminability conditions, correct responses were further associated with higher post-stimulus phase-locking than incorrect ones, in increasing frequency and latency. Finally, the larger the set size, the later the post-stimulus effect peaked. Together, these results suggest that increased complexity (lower discriminability or larger set size) requires more attentional cycles to perform the task, partially explaining discrepancies between reports of attentional sampling. Low-frequency oscillations structure the temporal dynamics of neural activity and aid top-down, attentional control for efficient visual processing.


Assuntos
Atenção , Percepção Visual , Atenção/fisiologia , Encéfalo/fisiologia , Eletroencefalografia , Periodicidade , Estimulação Luminosa/métodos , Percepção Visual/fisiologia
5.
Dev Cogn Neurosci ; 54: 101102, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35398645

RESUMO

An individual's early interactions with their environment are thought to be largely passive; through the early years, the capacity for volitional control develops. Here, we consider: how is the emergence of volitional control characterised by changes in the entrainment observed between internal activity (behaviour, physiology and brain activity) and the sights and sounds in our everyday environment (physical and social)? We differentiate between contingent responsiveness (entrainment driven by evoked responses to external events) and oscillatory entrainment (driven by internal oscillators becoming temporally aligned with external oscillators). We conclude that ample evidence suggests that children show behavioural, physiological and neural entrainment to their physical and social environment, irrespective of volitional attention control; however, evidence for oscillatory entrainment beyond contingent responsiveness is currently lacking. Evidence for how oscillatory entrainment changes over developmental time is also lacking. Finally, we suggest a mechanism through which periodic environmental rhythms might facilitate both sensory processing and the development of volitional control even in the absence of oscillatory entrainment.


Assuntos
Atenção , Periodicidade , Atenção/fisiologia , Criança , Humanos
6.
Cell Rep ; 39(2): 110678, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35417714

RESUMO

In the brain, oscillatory strength embedded in network rhythmicity is important for processing experiences, and this process is disrupted in certain psychiatric disorders. The use of rhythmic network stimuli can change these oscillations and has shown promise in terms of improving cognitive function, although the underlying mechanisms are poorly understood. Here, we combine a two-layer learning model, with experiments involving genetically modified mice, that provides precise control of experience-driven oscillations by manipulating long-term potentiation of excitatory synapses onto inhibitory interneurons (LTPE→I). We find that, in the absence of LTPE→I, impaired network dynamics and memory are rescued by activating inhibitory neurons to augment the power in theta and gamma frequencies, which prevents network overexcitation with less inhibitory rebound. In contrast, increasing either theta or gamma power alone was less effective. Thus, inducing network changes at dual frequencies is involved in memory encoding, indicating a potentially feasible strategy for optimizing network-stimulating therapies.


Assuntos
Hipocampo , Interneurônios , Animais , Hipocampo/fisiologia , Humanos , Interneurônios/fisiologia , Aprendizagem , Potenciação de Longa Duração/fisiologia , Camundongos , Periodicidade , Sinapses/fisiologia
7.
Front Neural Circuits ; 16: 846905, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35310550

RESUMO

A century worth of research has linked multiple cognitive, perceptual and behavioral states to various brain oscillations. However, the mechanistic roles and circuit underpinnings of these oscillations remain an area of active study. In this review, we argue that the advent of optogenetic and related systems neuroscience techniques has shifted the field from correlational to causal observations regarding the role of oscillations in brain function. As a result, studying brain rhythms associated with behavior can provide insight at different levels, such as decoding task-relevant information, mapping relevant circuits or determining key proteins involved in rhythmicity. We summarize recent advances in this field, highlighting the methods that are being used for this purpose, and discussing their relative strengths and limitations. We conclude with promising future approaches that will help unravel the functional role of brain rhythms in orchestrating the repertoire of complex behavior.


Assuntos
Optogenética , Periodicidade , Optogenética/métodos , Ritmo Teta
8.
J Acoust Soc Am ; 151(2): 712, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35232067

RESUMO

Humans are able to follow a speaker even in challenging acoustic conditions. The perceptual mechanisms underlying this ability remain unclear. A computational model of attentive voice tracking, consisting of four computational blocks: (1) sparse periodicity-based auditory features (sPAF) extraction, (2) foreground-background segregation, (3) state estimation, and (4) top-down knowledge, is presented. The model connects the theories about auditory glimpses, foreground-background segregation, and Bayesian inference. It is implemented with the sPAF, sequential Monte Carlo sampling, and probabilistic voice models. The model is evaluated by comparing it with the human data obtained in the study by Woods and McDermott [Curr. Biol. 25(17), 2238-2246 (2015)], which measured the ability to track one of two competing voices with time-varying parameters [fundamental frequency (F0) and formants (F1,F2)]. Three model versions were tested, which differ in the type of information used for the segregation: version (a) uses the oracle F0, version (b) uses the estimated F0, and version (c) uses the spectral shape derived from the estimated F0 and oracle F1 and F2. Version (a) simulates the optimal human performance in conditions with the largest separation between the voices, version (b) simulates the conditions in which the separation in not sufficient to follow the voices, and version (c) is closest to the human performance for moderate voice separation.


Assuntos
Percepção da Fala , Voz , Acústica , Teorema de Bayes , Simulação por Computador , Humanos , Periodicidade , Acústica da Fala
9.
J Physiol ; 600(11): 2537-2539, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35279844
10.
Cephalalgia ; 42(7): 570-578, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35112933

RESUMO

BACKGROUND: Contrary to pre-attack symptoms before an individual cluster headache attack, little is known about the pre-cluster symptoms before the onset of cluster bouts. We previously described pre-attack symptoms before cluster headache attacks. The aim of this study was to investigate characteristics of pre-cluster symptoms in patients with episodic cluster headache. METHODS: In this multicentre study, 184 patients with episodic cluster headache were recruited between October 2018 and December 2020. They were interviewed by investigators and completed a structured questionnaire. To investigate pre-cluster and pre-attack symptoms, we assessed 20 symptoms and signs using the questionnaire. RESULTS: The upcoming cluster bout was predictable in 35.3% (n = 65/184) of the patients. When present, pre-cluster symptoms occurred at a median duration of 7 days (interquartile range, 2.3-14 days) before the onset of the cluster bout. Patients with pre-cluster symptoms showed a higher proportion of women, prevalence of pre-attack symptoms and seasonal rhythmicity, frequency of cluster headache attacks per day, and total number of cluster bouts compared to patients without pre-cluster symptoms. In univariable and multivariable logistic regression analyses, female sex was associated with the predictability of pre-cluster symptoms (odds ratio = 2.297, p = 0.016). CONCLUSIONS: The upcoming cluster bout was predicted in approximately 35% of patients with episodic cluster headache, which may allow for an earlier preventive treatment and help understand the pathophysiology.


Assuntos
Cefaleia Histamínica , Cefaleia Histamínica/complicações , Cefaleia Histamínica/diagnóstico , Cefaleia Histamínica/epidemiologia , Estudos Transversais , Feminino , Humanos , Periodicidade , Prevalência , Inquéritos e Questionários
11.
Curr Biol ; 32(6): 1439-1445.e3, 2022 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-35148862

RESUMO

In many animals, the daily cycling of light is a key environmental cue, encoded in part by specialized light-sensitive neurons without visual functions. We serendipitously discovered innate light-responsiveness while imaging the extensively studied stomatogastric ganglion (STG) of the crab, Cancer borealis. The STG houses a motor circuit that controls the rhythmic contractions of the foregut, and the system has facilitated deep understanding of circuit function and neuromodulation. We illuminated the crab STG in vitro with different wavelengths and amplitudes of light and found a dose-dependent increase in neuronal activity upon exposure to blue light (λ460-500 nm). The response was elevated in the absence of neuromodulatory inputs to the STG. The pacemaker kernel that drives the network rhythm was responsive to light when synaptically isolated, and light shifted the threshold for slow wave and spike activity in the hyperpolarized direction, accounting for the increased activity patterns. Cryptochromes are evolutionarily conserved blue-light photoreceptors that are involved in circadian behaviors.1 Their activation by light can lead to enhanced neuronal activity.2 We identified cryptochrome sequences in the C. borealis transcriptome as potential mediators of this response and confirmed their expression in pyloric dilator (PD) neurons, which are part of the pacemaker kernel, by single-cell RNA-seq analysis.


Assuntos
Braquiúros , Neoplasias , Animais , Braquiúros/fisiologia , Gânglios , Gânglios dos Invertebrados/metabolismo , Neoplasias/metabolismo , Neurônios/fisiologia , Periodicidade
12.
Glob Chang Biol ; 28(10): 3349-3364, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35218086

RESUMO

Coral reefs are in global decline due to climate change and anthropogenic influences (Hughes et al., Conservation Biology, 27: 261-269, 2013). Near coastal cities or other densely populated areas, coral reefs face a range of additional challenges. While considerable progress has been made in understanding coral responses to acute individual stressors (Dominoni et al., Nature Ecology & Evolution, 4: 502-511, 2020), the impacts of chronic exposure to varying combinations of sensory pollutants are largely unknown. To investigate the impacts of urban proximity on corals, we conducted a year-long in-natura study-incorporating sampling at diel, monthly, and seasonal time points-in which we compared corals from an urban area to corals from a proximal non-urban area. Here we reveal that despite appearing relatively healthy, natural biorhythms and environmental sensory systems were extensively disturbed in corals from the urban environment. Transcriptomic data indicated poor symbiont performance, disturbance to gametogenic cycles, and loss or shifted seasonality of vital biological processes. Altered seasonality patterns were also observed in the microbiomes of the urban coral population, signifying the impact of urbanization on the holobiont, rather than the coral host alone. These results should raise alarm regarding the largely unknown long-term impacts of sensory pollution on the resilience and survival of coral reefs close to coastal communities.


Assuntos
Antozoários , Microbiota , Animais , Antozoários/fisiologia , Recifes de Corais , Periodicidade , Urbanização
14.
eNeuro ; 9(1)2022.
Artigo em Inglês | MEDLINE | ID: mdl-35058309

RESUMO

The action of acetylcholine in the cortex is critical for cognitive functions and cholinergic drugs can improve functions such as attention and working memory. An alternative means of enhancing cholinergic neuromodulation in primates is the intermittent electrical stimulation of the cortical source of acetylcholine, the nucleus basalis (NB) of Meynert. NB stimulation generally increases firing rate of neurons in the prefrontal cortex, however its effects on single neurons are diverse and complex. We sought to understand how NB stimulation affects global measures of neural activity by recording and analyzing local field potentials (LFPs) in monkeys as they performed working memory tasks. NB stimulation primarily decreased power in the alpha frequency range during the delay interval of working memory tasks. The effect was consistent across variants of the task. No consistent modulation in the delay interval of the task was observed in the gamma frequency range, which has previously been implicated in the maintenance of working memory. Our results reveal global effects of cholinergic neuromodulation via deep brain stimulation, an emerging intervention for the improvement of cognitive function.


Assuntos
Núcleo Basal de Meynert , Memória de Curto Prazo , Acetilcolina/farmacologia , Animais , Núcleo Basal de Meynert/fisiologia , Memória de Curto Prazo/fisiologia , Periodicidade , Córtex Pré-Frontal/fisiologia
15.
PLoS One ; 17(1): e0262239, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34986195

RESUMO

INTRODUCTION: In cholera endemic areas, the periodicity of cholera outbreaks remains unpredictable, making it difficult to organize preventive efforts. Lack of data on duration of protection conferred by oral cholera vaccines further makes it difficult to determine when to deploy preemptive vaccination. We report on the immunogenicity and waning of immunity to Shanchol™ in Lukanga Swamps. METHODS: We enrolled a cohort of 223 participants aged between 18 and 65 years old from whom serum samples were collected at baseline, day 28 before administration of the second dose, and consecutively at 6, 12, 24, 30, 36, and 48 months. Vibriocidal antibody titres were measured and expressed as geometric mean titres. Box plots and 95% CI were computed at each visit for both Inaba and Ogawa. Seroconversion was defined as a four fold or greater increase in antibody titres compared to baseline titres. RESULTS: Overall, seroconversion against V. cholerae Inaba and Ogawa after 1st dose was 35/134 (26%) and 34/134 (25%) respectively. We observed a statistical difference in seroconversion between the two subgroups of baseline titres (low <80 and high ≥80) for both Inaba (p = 0.02) and Ogawa (p<0.0001). From a baseline of 13.58, anti-Ogawa GMT increased to 21.95 after the first dose, but rapidly waned to 14.52, 13.13, and 12.78 at months 6, 12 and 24 respectively, and then increased to 13.21, 18.67 and 23.65 at months 30, 36 and 48 respectively. A similar trend was observed for anti-Inaba GMT across the same time points. CONCLUSION: We found that Shanchol™ was immunogenic in our study population and that vibriocidal antibodies may not be a good marker for long-term immunity. The observed rise in titres after 36 months suggests natural exposure, and this may be a critical time window opening for natural transmission in an endemic areas. We recommend re-vaccination at this time point in high risk areas.


Assuntos
Anticorpos Antibacterianos/sangue , Vacinas contra Cólera/administração & dosagem , Cólera/prevenção & controle , Vibrio cholerae/imunologia , Administração Oral , Adolescente , Adulto , Cólera/epidemiologia , Cólera/imunologia , Vacinas contra Cólera/imunologia , Doenças Endêmicas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Periodicidade , Vigilância da População , Soroconversão , Vibrio cholerae/classificação , Áreas Alagadas , Adulto Jovem , Zâmbia/epidemiologia
16.
Reprod Domest Anim ; 57(5): 498-504, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35066924

RESUMO

The aim of this study was to determine the metabolic status, stress and ovarian activity through progesterone profile in dairy buffalo as influenced by post-partum days, body condition score (BCS) and lactation number. A total of 45 dairy buffaloes were involved and divided into three factors based on their BCS (2.5, 3.0 and 3.5, respectively), lactation number (1, 2 and 3, respectively), and post-partum intervals (14, 28, 42 and 56, respectively). Based on findings, from day 14 to day 56 after parturition, blood glucose, cholesterol and triglyceride levels increased significantly (p < .01), while malondialdehyde (MDA) and cortisol levels decreased significantly (p < .05) on day 56 of the trial. With increased BCS levels, milk yield, blood metabolites and progesterone improved significantly (p < .05), whereas stress indicators decreased significantly (p < .01). Blood metabolites, progesterone and milk production were significantly (p < .01) higher and stress indicators (MDA and cortisol) were significantly (p < .01) lower in lactation stage. Buffaloes with a greater lactation stage and growing post-partum stage had better blood metabolite and progesterone concentrations and less stress. It was concluded that better BCS and increased lactation stage have significant impact on milk yield, stress reduction and restoration of ovarian activity in buffaloes during post-partum period.


Assuntos
Bison , Búfalos , Animais , Feminino , Hidrocortisona/metabolismo , Lactação , Leite , Estresse Oxidativo , Periodicidade , Período Pós-Parto , Progesterona
17.
J Neurosci ; 42(3): 500-512, 2022 01 19.
Artigo em Inglês | MEDLINE | ID: mdl-34848500

RESUMO

Predicting and organizing patterns of events is important for humans to survive in a dynamically changing world. The motor system has been proposed to be actively, and necessarily, engaged in not only the production but the perception of rhythm by organizing hierarchical timing that influences auditory responses. It is not yet well understood how the motor system interacts with the auditory system to perceive and maintain hierarchical structure in time. This study investigated the dynamic interaction between auditory and motor functional sources during the perception and imagination of musical meters. We pursued this using a novel method combining high-density EEG, EMG, and motion capture with independent component analysis to separate motor and auditory activity during meter imagery while robustly controlling against covert movement. We demonstrated that endogenous brain activity in both auditory and motor functional sources reflects the imagination of binary and ternary meters in the absence of corresponding acoustic cues or overt movement at the meter rate. We found clear evidence for hypothesized motor-to-auditory information flow at the beat rate in all conditions, suggesting a role for top-down influence of the motor system on auditory processing of beat-based rhythms, and reflecting an auditory-motor system with tight reciprocal informational coupling. These findings align with and further extend a set of motor hypotheses from beat perception to hierarchical meter imagination, adding supporting evidence to active engagement of the motor system in auditory processing, which may more broadly speak to the neural mechanisms of temporal processing in other human cognitive functions.SIGNIFICANCE STATEMENT Humans live in a world full of hierarchically structured temporal information, the accurate perception of which is essential for understanding speech and music. Music provides a window into the brain mechanisms of time perception, enabling us to examine how the brain groups musical beats into, for example a march or waltz. Using a novel paradigm combining measurement of electrical brain activity with data-driven analysis, this study directly investigates motor-auditory connectivity during meter imagination. Findings highlight the importance of the motor system in the active imagination of meter. This study sheds new light on a fundamental form of perception by demonstrating how auditory-motor interaction may support hierarchical timing processing, which may have clinical implications for speech and motor rehabilitation.


Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Imaginação/fisiologia , Música/psicologia , Percepção do Tempo/fisiologia , Estimulação Acústica , Eletroencefalografia , Eletromiografia , Feminino , Humanos , Masculino , Músculo Esquelético/fisiologia , Periodicidade , Adulto Jovem
18.
J Neurosci ; 42(5): 894-908, 2022 02 02.
Artigo em Inglês | MEDLINE | ID: mdl-34893547

RESUMO

Auditory stimuli are often rhythmic in nature. Brain activity synchronizes with auditory rhythms via neural entrainment, and entrainment seems to be beneficial for auditory perception. However, it is not clear to what extent neural entrainment in the auditory system is reliable over time, which is a necessary prerequisite for targeted intervention. The current study aimed to establish the reliability of neural entrainment over time and to predict individual differences in auditory perception from associated neural activity. Across two different sessions, human listeners (21 females, 17 males) detected silent gaps presented at different phase locations of a 2 Hz frequency-modulated (FM) noise while EEG activity was recorded. As expected, neural activity was entrained by the 2 Hz FM noise. Moreover, gap detection was sinusoidally modulated by the phase of the 2 Hz FM into which the gap fell. Critically, both the strength of neural entrainment as well as the modulation of performance by the stimulus rhythm were highly reliable over sessions. Moreover, gap detection was predictable from pregap neural 2 Hz phase and alpha amplitude. Our results demonstrate that neural entrainment in the auditory system and the resulting behavioral modulation are reliable over time, and both entrained delta and nonentrained alpha oscillatory activity contribute to near-threshold stimulus perception. The latter suggests that improving auditory perception might require simultaneously targeting entrained brain rhythms as well as the alpha rhythm.SIGNIFICANCE STATEMENT Neural activity synchronizes to the rhythms in sounds via neural entrainment, which seems to be important for successful auditory perception. A natural hypothesis is that improving neural entrainment, for example, via brain stimulation, should benefit perception. However, the extent to which neural entrainment is reliable over time, a necessary prerequisite for targeted intervention, has not been established. Using electroencephalogram recordings, we demonstrate that both neural entrainment to FM sounds and stimulus-induced behavioral modulation are reliable over time. Moreover, moment-by-moment fluctuations in perception are best predicted by entrained delta phase and nonentrained alpha amplitude. This work suggests that improving auditory perception might require simultaneously targeting entrained brain rhythms as well as the alpha rhythm.


Assuntos
Ritmo alfa , Córtex Auditivo/fisiologia , Ritmo Delta , Periodicidade , Adulto , Vias Auditivas/fisiologia , Percepção Auditiva , Potenciais Evocados Auditivos , Feminino , Humanos , Masculino
19.
ISA Trans ; 122: 205-217, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33992420

RESUMO

This paper tackles the global polynomial periodicity (GPP) and global polynomial stability (GPS) for proportional delay Cohen-Grossberg neural networks (PDCGNNs). By adopting two transformations, designing opportune Lyapunov functionals (LFs) with tunable parameters and taking inequality skills, several delay-dependent criteria of GPP and GPS are acquired for the PDCGNNs. Here the GPP is also a kind of global asymptotic periodicity (GAP), but it has obvious convergence rate and convergence order, and its convergence rate is slower than that of global exponential periodicity (GEP). This is of great significance to the detailed division of periodicity in theory. These acquired criteria are confirmed by a numerical example with four cases. Simultaneously, through the numerical example, the acquired criteria also fully demonstrate their superiority in comparison with existing results. And, in another example, a GPS criterion is used to solve a quadratic programming problem (QPP) to reflect one of the practical applications of the PDCGNNs.


Assuntos
Algoritmos , Redes Neurais de Computação , Periodicidade , Registros , Fatores de Tempo
20.
QJM ; 114(11): 773-779, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-33394049

RESUMO

BACKGROUND: The Acute Medical Unit (AMU) provides care for unscheduled hospital admissions. Seven-day consultant presence and morning AMU discharges have been advocated to improve hospital bed management. AIMS: To determine whether a later time of daily peak AMU occupancy correlates with measures of hospital stress; whether 7-day consultant presence, for COVID-19, abolished weekly periodicity of discharges. DESIGN: Retrospective cohort analysis. METHODS: : Anonymised AMU admission and discharge times were retrieved from the Profile Information Management System (PIMS), at a large, urban hospital from 14 April 2014 to 31 December 2018 and 20 March to 2 May 2020 (COVID-19 peak). Minute-by-minute admission and discharge times were combined to construct a running total of AMU bed occupancy. Fourier transforms were used to determine periodicity. We tested association between (i) average AMU occupancy and (ii) time of peak AMU occupancy, with measures of hospital stress (total medical bed occupancy and 'medical outliers' on non-medical wards). RESULTS: : Daily, weekly and seasonal patterns of AMU bed occupancy were evident. Timing of AMU peak occupancy was unrelated to each measure of hospital stress: total medical inpatients (Spearman's rho, rs = 0.04, P = 0.24); number of medical outliers (rs = -0.06, P = 0.05). During COVID-19, daily bed occupancy was similar, with continuation of greater Friday and Monday discharges than the weekend. CONCLUSIONS: : Timing of peak AMU occupancy did not alter with hospital stress. Efforts to increase morning AMU discharges are likely to have little effect on hospital performance. Seven-day consultant presence did not abolish weekly periodicity of discharges-other factors influence weekend discharges.


Assuntos
COVID-19 , Ocupação de Leitos , Hospitais , Humanos , Tempo de Internação , Periodicidade , Estudos Retrospectivos , SARS-CoV-2
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