Error feedback loop linearizes direct digital synthesizers

Author(s):  
F. Harris ◽  
B. McKnight
Keyword(s):  
2021 ◽  
Author(s):  
Matthew S Price

Leukocyte telomere shortening is a useful biomarker of biological and cellular age that occurs at an accelerated rate in anxiety disorders and posttraumatic stress disorder (PTSD). Intriguingly, inhibitory learning — the systematic exposure to noxious stimuli that serves as a basis for many treatments for anxiety, phobia, and PTSD —reduces relative telomeres attrition rates and increases protective telomerase activity in a manner predictive of treatment response. How does inhibitory learning, a behavioral strategy, modulate organismal chromosomal activity? Inhibitory learning may induce repeated mismatch between treatment expectations, intrasession states, and eventual outcome. Nevertheless, inhibitory learning can incentivize repetition of the behavior. Thus, this paper aims to conceptualize inhibitory learning as involving a ‘prediction error feedback loop’, i.e., a series of self-perpetuating prediction errors — mismatches between expectations and outcomes — that enhances neural inhibitory regulation to effectuate extinction. Inhibitory learning is necessarily predicated upon an opposing process – excitatory learning – that may be conceptualized as a prediction error feedback loop that operates in reverse to inhibitory learning and enhances neural excitability as arousal. Together, excitatory and inhibitory learning may be elements of an associative learning prediction error feedback loop responsible for modulating neural bioenergetic rates, leading to changes in downstream cellular signaling that could explain reduced or increased rates of leukocyte telomere shortening and telomerase activity from each behavioral strategy, respectively.


2021 ◽  
Author(s):  
Matthew S Price

Inhibitory learning promotes emotion regulation via systematic exposure to fear-inducing stimuli. Given that inconsistencies between expectations, states, and outcomes may be experienced as elements of inhibitory learning, to what extent are prediction errors – mismatches between expectations and outcomes – a core neural element of inhibitory learning? This paper takes a complex systems approach to prediction errors and postulates that a prediction error feedback loop – a series of self-perpetuating disparities between expected and perceived outcomes – could be a correlate of or responsible for improved emotion regulation from inhibitory learning. The inhibitory learning prediction error feedback loop may additionally elucidate how human and animal studies demonstrate improved emotion regulation in the form of reduced fear responses without exposure to specific fear-inducing stimuli.


2014 ◽  
Vol 43 (11) ◽  
pp. 1671-1686 ◽  
Author(s):  
Stanislaw Szczepanski ◽  
Bogdan Pankiewicz ◽  
Slawomir Koziel ◽  
Marek Wojcikowski

2015 ◽  
Vol 58 ◽  
pp. 83-100 ◽  
Author(s):  
Selena Gimenez-Ibanez ◽  
Marta Boter ◽  
Roberto Solano

Jasmonates (JAs) are essential signalling molecules that co-ordinate the plant response to biotic and abiotic challenges, as well as co-ordinating several developmental processes. Huge progress has been made over the last decade in understanding the components and mechanisms that govern JA perception and signalling. The bioactive form of the hormone, (+)-7-iso-jasmonyl-l-isoleucine (JA-Ile), is perceived by the COI1–JAZ co-receptor complex. JASMONATE ZIM DOMAIN (JAZ) proteins also act as direct repressors of transcriptional activators such as MYC2. In the emerging picture of JA-Ile perception and signalling, COI1 operates as an E3 ubiquitin ligase that upon binding of JA-Ile targets JAZ repressors for degradation by the 26S proteasome, thereby derepressing transcription factors such as MYC2, which in turn activate JA-Ile-dependent transcriptional reprogramming. It is noteworthy that MYCs and different spliced variants of the JAZ proteins are involved in a negative regulatory feedback loop, which suggests a model that rapidly turns the transcriptional JA-Ile responses on and off and thereby avoids a detrimental overactivation of the pathway. This chapter highlights the most recent advances in our understanding of JA-Ile signalling, focusing on the latest repertoire of new targets of JAZ proteins to control different sets of JA-Ile-mediated responses, novel mechanisms of negative regulation of JA-Ile signalling, and hormonal cross-talk at the molecular level that ultimately determines plant adaptability and survival.


2014 ◽  
Vol 1 ◽  
pp. 636-639
Author(s):  
Fernanda S. Matias ◽  
Pedro V. Carelli ◽  
Claudio R. Mirasso ◽  
Mauro Copelli

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