scholarly journals Feedback Network Controls Photoreceptor Output at the Layer of First Visual Synapses in Drosophila

2006 ◽  
Vol 127 (5) ◽  
pp. 495-510 ◽  
Author(s):  
Lei Zheng ◽  
Gonzalo G. de Polavieja ◽  
Verena Wolfram ◽  
Musa H. Asyali ◽  
Roger C. Hardie ◽  
...  
Keyword(s):  
Compound Eye ◽  
Amacrine Cells ◽  
Feedback Network ◽  
Coding Strategies ◽  
Neural Information ◽  
Neural Information Processing ◽  
Light Stimuli ◽  
The Brain

At the layer of first visual synapses, information from photoreceptors is processed and transmitted towards the brain. In fly compound eye, output from photoreceptors (R1–R6) that share the same visual field is pooled and transmitted via histaminergic synapses to two classes of interneuron, large monopolar cells (LMCs) and amacrine cells (ACs). The interneurons also feed back to photoreceptor terminals via numerous ligand-gated synapses, yet the significance of these connections has remained a mystery. We investigated the role of feedback synapses by comparing intracellular responses of photoreceptors and LMCs in wild-type Drosophila and in synaptic mutants, to light and current pulses and to naturalistic light stimuli. The recordings were further subjected to rigorous statistical and information-theoretical analysis. We show that the feedback synapses form a negative feedback loop that controls the speed and amplitude of photoreceptor responses and hence the quality of the transmitted signals. These results highlight the benefits of feedback synapses for neural information processing, and suggest that similar coding strategies could be used in other nervous systems.

scholarly journals Consciousness, decision making, and volition: freedom beyond chance and necessity

2021 ◽  
Author(s):  
Hans Liljenström
Keyword(s):  
Decision Making ◽  
Free Will ◽  
Brain Activity ◽  
Brain Structures ◽  
Complex Process ◽  
Neural Information ◽  
Neural Information Processing ◽  
Stochastic Population Model ◽  
The Brain

AbstractWhat is the role of consciousness in volition and decision-making? Are our actions fully determined by brain activity preceding our decisions to act, or can consciousness instead affect the brain activity leading to action? This has been much debated in philosophy, but also in science since the famous experiments by Libet in the 1980s, where the current most common interpretation is that conscious free will is an illusion. It seems that the brain knows, up to several seconds in advance what “you” decide to do. These studies have, however, been criticized, and alternative interpretations of the experiments can be given, some of which are discussed in this paper. In an attempt to elucidate the processes involved in decision-making (DM), as an essential part of volition, we have developed a computational model of relevant brain structures and their neurodynamics. While DM is a complex process, we have particularly focused on the amygdala and orbitofrontal cortex (OFC) for its emotional, and the lateral prefrontal cortex (LPFC) for its cognitive aspects. In this paper, we present a stochastic population model representing the neural information processing of DM. Simulation results seem to confirm the notion that if decisions have to be made fast, emotional processes and aspects dominate, while rational processes are more time consuming and may result in a delayed decision. Finally, some limitations of current science and computational modeling will be discussed, hinting at a future development of science, where consciousness and free will may add to chance and necessity as explanation for what happens in the world.

GLOBAL EFFECTS OF FLUCTUATIONS IN NEURAL INFORMATION PROCESSING

1996 ◽  
Vol 07 (04) ◽  
pp. 497-505 ◽  
Author(s):  
HANS LILJENSTRÖM
Keyword(s):  
Information Processing ◽  
Neuronal Excitability ◽  
Complex Dynamics ◽  
Memory State ◽  
Cortical Dynamics ◽  
Neural Information ◽  
Neural Information Processing ◽  
Correct Pattern ◽  
The Brain

We are interested in how the complex dynamics of the brain, which may include oscillations, chaos and noise, can affect the efficiency of neural information processing. Here, we consider the amplification and functional role of fluctuations, expressed as chaos or noise in the system. Using computer simulations of a neural network model of the olfactory cortex, we demonstrate how microscopic fluctuations can result in global effects at the network level. In particular, we show that the rate of information processing in associative memory tasks can be maximized for optimal noise levels. Noise can also induce transitions between different dynamical states, related to learning and memory. A chaotic-like behavior, induced by noise or by an increase in neuronal excitability, can enhance system performance if it is transient and converges to a limit cycle memory state. The level of accuracy required for correct pattern association further affects the rate of information processing. We discuss how neuromodulatory control of the cortical dynamics can shift the balance between rate and accuracy optimization, as well as between sensitivity and stability.

Considerations on the Use of Aromatase Inhibitors in Postmenopausal Women With Breast Cancer

2020 ◽  
pp. 385-400
Author(s):  
Jeffrey D. Blaustein
Keyword(s):  
Breast Cancer ◽  
Quality Of Life ◽  
Cognitive Function ◽  
Adverse Effects ◽  
Develop Breast Cancer ◽  
Laboratory Animals ◽  
Breast Cancers ◽  
The Brain

About 1 of every 8 women will develop breast cancer during her lifetime, and approximately 250,000 new cancer cases are expected annually as of 2017. Of those breast cancers, approximately 60% to 75% will express estrogen receptors, suggesting that estrogens are likely to promote growth of those tumors. Because the use of inhibitors of the synthesis of estrogens is the adjuvant treatment of choice for many women, it is essential that we understand the potential adverse effects on quality of life of those treatments. This review addresses the role of estrogens locally synthesized in the brain in laboratory animals and women, the effects of estrogens on cognitive function, the effects of synthesis blockers on cognitive function, and the limitations in performing experiments that will give us strong confidence in the results and conclusions.

scholarly journals Role of estrogen and stress on the brain-gut axis

2019 ◽  
Vol 317 (2) ◽  
pp. G203-G209 ◽  
Author(s):  
Yanyan Jiang ◽  
Beverley Greenwood-Van Meerveld ◽  
Anthony C. Johnson ◽  
R. Alberto Travagli
Keyword(s):  
Functional Gastrointestinal Disorders ◽  
Clinical Problem ◽  
Visceral Sensitivity ◽  
Physiological Mechanisms ◽  
Acute And Chronic Stress ◽  
Highly Correlated ◽  
The Brain ◽  
Gi Motility

Symptoms of functional gastrointestinal disorders (FGIDs), including fullness, bloating, abdominal pain, and altered gastrointestinal (GI) motility, present a significant clinical problem, with a reported prevalence of 25%–40% within the general population. More than 60% of those affected seek and require healthcare, and affected individuals report a significantly decreased quality of life. FGIDs are highly correlated with episodes of acute and chronic stress and are increased in prevalence and reported severity in women compared with men. Although there is evidence that sex and stress interact to exacerbate FGID symptoms, the physiological mechanisms that mediate these sex-dependent disparities are incompletely understood, although hormonal-related differences in GI motility and visceral sensitivity have been purported to play a significant role in the etiology. In this mini review, we will discuss brain-gut axis control of GI motility and sensitivity, the influence of estrogen on GI motility and sensitivity, and stress modulation of the brain-gut axis.

scholarly journals The Role of Adrenoceptors in the Retina

Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2594
Author(s):  
Yue Ruan ◽  
Tobias Böhmer ◽  
Subao Jiang ◽  
Adrian Gericke
Keyword(s):  
Visual Information ◽  
Vision Loss ◽  
Retinal Diseases ◽  
System A ◽  
The Central Nervous System ◽  
The Individual ◽  
And Function ◽  
The Brain

The retina is a part of the central nervous system, a thin multilayer with neuronal lamination, responsible for detecting, preprocessing, and sending visual information to the brain. Many retinal diseases are characterized by hemodynamic perturbations and neurodegeneration leading to vision loss and reduced quality of life. Since catecholamines and respective bindings sites have been characterized in the retina, we systematically reviewed the literature with regard to retinal expression, distribution and function of alpha1 (α1)-, alpha2 (α2)-, and beta (β)-adrenoceptors (ARs). Moreover, we discuss the role of the individual adrenoceptors as targets for the treatment of retinal diseases.

scholarly journals Principles for models of neural information processing

2017 ◽  
Author(s):  
Kendrick N. Kay ◽  
Kevin S. Weiner
Keyword(s):  
Information Processing ◽  
Cognitive Neuroscience ◽  
Brain Function ◽  
Network Models ◽  
Neural Network Models ◽  
Specific Effects ◽  
Neural Information ◽  
Neural Information Processing ◽  
The Difference ◽  
The Brain

AbstractThe goal of cognitive neuroscience is to understand how mental operations are performed by the brain. Given the complexity of the brain, this is a challenging endeavor that requires the development of formal models. Here, we provide a perspective on models of neural information processing in cognitive neuroscience. We define what these models are, explain why they are useful, and specify criteria for evaluating models. We also highlight the difference between functional and mechanistic models, and call attention to the value that neuroanatomy has for understanding brain function. Based on the principles we propose, we proceed to evaluate the merit of recently touted deep neural network models. We contend that these models are promising, but substantial work is necessary to (i) clarify what type of explanation these models provide, (ii) determine what specific effects they accurately explain, and (iii) improve our understanding of how they work.

scholarly journals Gap junction networks in mushroom bodies participate in visual learning and memory in Drosophila

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Qingqing Liu ◽  
Xing Yang ◽  
Jingsong Tian ◽  
Zhongbao Gao ◽  
Meng Wang ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Gap Junction ◽  
Learning And Memory ◽  
Visual Learning ◽  
Mushroom Bodies ◽  
Single Pair ◽  
Neural Information ◽  
Neural Information Processing ◽  
Coupling Approach

Gap junctions are widely distributed in the brains across species and play essential roles in neural information processing. However, the role of gap junctions in insect cognition remains poorly understood. Using a flight simulator paradigm and genetic tools, we found that gap junctions are present in Drosophila Kenyon cells (KCs), the major neurons of the mushroom bodies (MBs), and showed that they play an important role in visual learning and memory. Using a dye coupling approach, we determined the distribution of gap junctions in KCs. Furthermore, we identified a single pair of MB output neurons (MBONs) that possess a gap junction connection to KCs, and provide strong evidence that this connection is also required for visual learning and memory. Together, our results reveal gap junction networks in KCs and the KC-MBON circuit, and bring new insight into the synaptic network underlying fly’s visual learning and memory.

Visions of vision: Studies of the horseshoe crab compound eye

1992 ◽  
Vol 50 (1) ◽  
pp. 488-489
Author(s):  
Steven C. Chamberlain
Keyword(s):  
Horseshoe Crab ◽  
Light Adaptation ◽  
Compound Eye ◽  
Visually Guided ◽  
Morphological Process ◽  
Morphological Studies ◽  
Visual Processes ◽  
Lateral Eye ◽  
The Brain

The lateral eye of the horseshoe crab, Limulus polyphemus, is an important model system for studies of visual processes such as phototransduction, lateral inhibition, and light adaptation. It has also been the system of choice for pioneering studies of the role of circadian efferent input from the brain to the eye. For example, light and efferent input interact in controlling the daily shedding of photosensitive membrane and photomechanical movements. Most recently, modeling efforts have begun to relate anatomy, physiology and visually guided behavior using parallel computing. My laboratory has pursued collaborative morphological studies of the compound eye for the past 15 years. Some of this research has been correlated structure/function studies; the rest has been studies of basic morphology and morphological process.

Treatments for Breast Cancer That Affect Cognitive Function in Postmenopausal Women

2017 ◽  
Vol 4 (2) ◽  
pp. 170-177 ◽  
Author(s):  
Jeffrey D. Blaustein
Keyword(s):  
Breast Cancer ◽  
Quality Of Life ◽  
Cognitive Function ◽  
Develop Breast Cancer ◽  
Laboratory Animals ◽  
Breast Cancers ◽  
Estrogen Synthesis ◽  
The Brain

About one of every eight women will develop breast cancer during her lifetime. Approximately a quarter of a million new cancer cases are expected in 2017. Of those breast cancers, 60% to 75% will have characteristics suggesting that estrogens are likely to promote growth of those tumors. Consequently, inhibiting estrogen synthesis is one of the main treatments of choice. Therefore, women must understand the potential adverse effects of those treatments on quality of life. This review discusses (a) the role of estrogens locally synthesized in the brain in laboratory animals and women, (b) the effects of estrogens and blockers of estrogen synthesis on cognitive function, and (c) the limitations in experiments on women taking inhibitors. This article aims to provide women and oncologists with information that will encourage them to consider side effects of aromatase inhibitors (AIs) treatment on the brain.

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