The dynamics of the 18 While the QCT calculations captured the experimental product vibrational energy distribution better than the QS method, the QCT results underpredicted rotationally-excited products, overpredicted forward-bias and predicted a trend in the strength of forward-bias with collision energy opposite to that measured, indicating that it does not completely capture the dynamic behavior measured in the experiment. Thus, these results further underscore the need for improvement in theoretical treatments of dynamics on the O 3 (X 1 A') PES and perhaps of the PES itself in order to better understand and predict non-statistical effects in this reaction and in the 3 formation of ozone (in which the intermediate O 3 * complex is collisionally stabilized by a third body). The scattering data presented here at two different collision energies provide important benchmarks to guide these improvements.
A repeating triplet-sequence ABA − of non-overlapping brief tones, A and B, is a valued paradigm for studying auditory stream formation and the cocktail party problem. The stimulus is "heard" either as a galloping pattern (integration) or as two interleaved streams (segregation); the initial percept is typically integration then followed by spontaneous alternations between segregation and integration, each being dominant for a few seconds. The probability of segregation grows over seconds, from near-zero to a steady value, defining the buildup function, BUF. Its stationary level increases with the difference in tone frequencies, DF, and the BUF rises faster. Percept durations have DF-dependent means and are gamma-like distributed. Behavioral and computational studies usually characterize triplet streaming either during alternations or during buildup. Here, our experimental design and modeling encompass both. We propose a pseudo-neuromechanistic model that incorporates spiking activity in primary auditory cortex, A1, as input and resolves perception along two network-layers downstream of A1. Our model is straightforward and intuitive. It describes the noisy accumulation of evidence against the current percept which generates switches when reaching a threshold. Accumulation can saturate either above or below threshold; if below, the switching dynamics resemble noise-induced transitions from an attractor state. Our model accounts quantitatively for three key features of data: the BUFs, mean durations, and normalized dominance duration distributions, at various DF values. It describes perceptual alternations without competition per se, and underscores that treating triplets in the sequence independently and averaging across trials, as implemented in earlier widely cited studies, is inadequate.
Synchronization in neural systems plays an important role in many brain functions. Synchronization in the gamma frequency band (30–100 Hz) is involved in a variety of cognitive phenomena; abnormalities of the gamma synchronization are found in schizophrenia and autism spectrum disorder. Frequently, the strength of synchronization is not high, and synchronization is intermittent even on short time scales (few cycles of oscillations). That is, the network exhibits intervals of synchronization followed by intervals of desynchronization. Neural circuit dynamics may show different distributions of desynchronization durations even if the synchronization strength is fixed. We use a conductance-based neural network exhibiting pyramidal-interneuron gamma rhythm to study the temporal patterning of synchronized neural oscillations. We found that changes in the synaptic strength (as well as changes in the membrane kinetics) can alter the temporal patterning of synchrony. Moreover, we found that the changes in the temporal pattern of synchrony may be independent of the changes in the average synchrony strength. Even though the temporal patterning may vary, there is a tendency for dynamics with short (although potentially numerous) desynchronizations, similar to what was observed in experimental studies of neural synchronization in the brain. Recent studies suggested that the short desynchronizations dynamics may facilitate the formation and the breakup of transient neural assemblies. Thus, the results of this study suggest that changes of synaptic strength may alter the temporal patterning of the gamma synchronization as to make the neural networks more efficient in the formation of neural assemblies and the facilitation of cognitive phenomena.
18A repeating triplet-sequence ABA − of non-overlapping brief tones, A and B, is a valued 19 paradigm for studying auditory stream formation and the cocktail party problem. The 20 stimulus is "heard" either as a galloping pattern (integration) or as two interleaved 21 streams (segregation); the initial percept is typically integration then followed by 22 spontaneous alternations between segregation and integration, each being dominant for 23 a few seconds. The probability of segregation grows over seconds, from near-zero to a 24 steady value, defining the buildup function, BUF. Its stationary level increases with the 25 difference in tone frequencies, DF , and the BUF rises faster. Percept durations have 26 DF -dependent means and are gamma-like distributed. Behavioral and computational 27 studies usually characterize triplet streaming either during alternations or during 28 buildup. Here, our experimental design and modeling encompass both. We propose a 29 pseudo-neuromechanistic model that incorporates spiking activity in primary auditory 30 cortex, A1, as input and resolves perception along two network-layers downstream of A1. 31 Our model is straightforward and intuitive. It describes the noisy accumulation of 32 evidence against the current percept which generates switches when reaching a 33 threshold. Accumulation can saturate either above or below threshold; if below, the 34 switching dynamics resemble noise-induced transitions from an attractor state. Our 35 model accounts quantitatively for three key features of data: the BUFs, mean durations, 36 and normalized dominance duration distributions, at various DF values. It describes 37 perceptual alternations without competition per se, and underscores that treating 38 triplets in the sequence independently and averaging across trials, as implemented in 39 earlier widely cited studies, is inadequate. 40 January 6, 2020 2/63 Author summary 41 Segregation of auditory objects (auditory streaming) is widely studied using ambiguous 42 stimuli. A sequence of repeating triplets ABA − of non-overlapping brief pure tones, A 43 and B, frequency-separated, is a valued stimulus. Studies typically focus on one of two 44 behavioral phases: the early (say, ten seconds) buildup of segregation from the default 45 integration or later spontaneous alternations (bistability) between seconds-long 46 integration and segregation percepts. Our experiments and modeling encompass both. 47 Our novel, data-driven, evidence-accumulation model accounts for key features of the 48 observations, taking as input recorded spiking activity from primary auditory cortex (as 49 opposed to most existing, more abstract, models). Our results underscore that assessing 50 individual triplets independently and averaging across trials, as in some earlier studies, 51 is inadequate (lacking neuronal-accountability for percept duration statistics, the 52 underlying basis of buildup). Further, we identify fresh parallels between evidence 53 accumulation and competition as potential dynamic processes for cho...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.