Modulation Of Neuronal Responses
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Modulation Of Neuronal Responses
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Author : Giedrius T. Buračas
language : en
Publisher: IOS Press
Release Date : 2003
Modulation Of Neuronal Responses written by Giedrius T. Buračas and has been published by IOS Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
Contextual And Attentional Modulation Of Neuronal Responses In Macaque Area
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Author : Kristy Ann Sundberg
language : en
Publisher:
Release Date : 2007
Contextual And Attentional Modulation Of Neuronal Responses In Macaque Area written by Kristy Ann Sundberg and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
One of the fundamental goals of neuroscience is to understand how sensory information is processed by the brain to give rise to our conscious experience of the world. One of the most striking features of our perception is that our brain does not process all incoming sensory information. Instead we only process in fine detail information that is currently at the focus of our attention and process at a much coarser scale the information outside of our attentional focus. We generally only become aware of the details of information outside this focus if a change in behavioral goals or a salient event initiates a shift in attention. We remain largely unaware of this two-tiered sensory processing when the brain is functioning normally. Failures of this attentional system, however, can be quite striking in disorders such as visual-spatial neglect and autism. The work contained within this dissertation is part of the large effort to understand sensory processing in the brain. In particular the work focuses on the way in which visual information is represented in extrastriate visual cortex and how the location of attentional focus can modulate this representation of visual information. The chapters of this dissertation represent three independent but related experimental studies addressing these questions through the use of electrophysiological recordings of area V4 in awake behaving animals. The first chapter focuses on characterizing the relationship between multiple measures of neural activity in area V4 to parametric variations of luminance contrast. The second chapter focuses on characterizing how attentional modulation of neuronal response in area V4 to a target item changes in the presence of a nearby distracter item. The final chapter focuses on the question of how the integration of motion and color information in area V4 may give rise to a visual illusion in which a color change embedded within a motion sequence is mislocalized by human observers. In all cases the goal of characterizing these visual responses was to provide insights into the neural mechanisms and circuitry underlying visual processing and sensory processing in general.
Modulation Of Neuronal Responses To L Glutamate In Aplysia
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Author : Michael J. McCreery
language : en
Publisher:
Release Date : 1984
Modulation Of Neuronal Responses To L Glutamate In Aplysia written by Michael J. McCreery and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1984 with Neural transmission categories.
Gain Modulation In Visual Cortex By Noisy Synaptic Inputs
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Author : Asli Ayaz
language : en
Publisher:
Release Date : 2009
Gain Modulation In Visual Cortex By Noisy Synaptic Inputs written by Asli Ayaz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
Gain modulation of neuronal responses is widely observed in the cerebral cortex of both anesthetized and behaving animals. This dissertation examines mechanisms that may underlie different forms of gain modulation observed in visual cortex. We examine mechanisms that arise at many levels, beginning at the single-cell level (modulating the effective reversal potential of synaptic inputs to a cell) and ending at the network level (nonlinear interactions arising through recurrent connectivity). In Chapter 2, we examine how the balance between excitation and inhibition in a neuron's input may affect how that neuron integrates its inputs. We have found that if excitatory and inhibitory inputs are balanced at a specific potential (we refer to this potential as the "balanced potential"), these do not alter the firing-rate responses, provided that they do not introduce additional noise. If these inputs do increase noise, their effect is close to input-gain modulation, an effect best described as scaling of the input. If the inputs are noisy but instead balanced at a more hyperpolarized potential, their effect is more like response-gain modulation, a divisive scaling of the neuron's firing rate. In Chapter 3, we compare the effects of noisy synaptic inputs in a configuration that divisively scales firing-rate curves with the effects of subtractive mechanisms of inhibition and explore their possible role in producing multiplicative gain modulation effects observed in vivo, such as surround suppression and attention. The divisive mechanism of inhibition is more successful in producing both response-gain and input-gain modulation effects although the effects of subtractive inhibition can appear nonlinear. Finally in Chapter 4, we examine how network effects can produce gain modulation phenomena. Specifically, we construct a recurrent network model of attention in visual cortex, and demonstrate how multiple forms of gain modulation can arise through nonlinear interactions that arise within a recurrent framework of connectivity. Gain modulation phenomena observed in vivo may arise from all or only a subset of the mechanisms examined in this study. As discussed in the final chapter, whole-cell recording techniques that measure in vivo conductance changes may allow distinguishing between these mechanisms.
Slow Synaptic Responses And Modulation
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Author : K. Kuba
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-04-17
Slow Synaptic Responses And Modulation written by K. Kuba and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-04-17 with Medical categories.
Information flow as nerve impulses in neuronal circuits is regulated at synapses. The synapse is therefore a key element for information processing in the brain. Much attention has been given to fast synaptic transmission, which predominantly regulates impulse-to-impulse transmission. Slow synaptic transmission and modu lation, however, sometimes have been neglected in considering and attempting to understand brain function. Slow synaptic potentials and modulation occur with a considerable delay in response to the accumulation of synaptic and modulatory inputs. In these contexts, they are plastic in nature and play important roles in information processing in the brain. A symposium titled "Slow Synaptic Responses and Modulation" was held as the satellite symposium to the 75th Annual Meeting of the Physiological Society of Japan on March 30-31, 1998, in Kanazawa. The theme was selected not only for the reason mentioned above, but also because of the considerable involvement of many Japanese scholars in establishing the basic issues. Following the dawn of synaptic physiological research, as Sir John Eccles, Sir Bernard Katz, and Professor Stephen Kuffler carried out pioneer work, Professor Kyozou Koketsu and Professor Benjamin Libet, the students of Sir John Eccles, and their colleagues established the concept of slow synaptic responses and modulation by studying vertebrate sympathetic ganglia. Since then, the concept has been ex panded with detailed investigations of both peripheral and central synapses at the levels of single ion channels, intracellular Ca"+ dynamics, intracellular transduc tion mechanisms, and genes.
Perceptual Consequences Of Surround Suppression And Plasticity In Visual Motion Processing
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Author : Liu Liu
language : en
Publisher:
Release Date : 2017
Perceptual Consequences Of Surround Suppression And Plasticity In Visual Motion Processing written by Liu Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
"The visual nervous system transforms the input from the visual scene into electrical signals. The electrical signals are in turn read out by other areas of the brain to form perceptual decisions. The relationship between neuronal responses evoked by sensory stimuli and their perceptual correlates is an important research question in modern computational and systems neuroscience. Previous studies of this relationship focused on correlating the response of single neurons to stimuli in their receptive field (RF), defined as a region of the visual space where selective stimuli can evoke a response. However, single neurons are part of a local circuitry that controls their selectivity and modulates their response. The local circuitry is composed of many neurons that encode surrounding regions of the visual space. The neurons in the circuit can interact via excitatory or inhibitory connections. The interactions are crucial for contextual modulation of single neuron response, since any stimulus on the RF of a neuron is part of a larger visual context. Aside from the contextual modulation of neuronal responses, another part of the sensory-to-decision transformation is how the responses of neurons are read out from a population. Correlations in the responses of neurons can have a large impact in the amount of information in a population, and this correlation should be quantified when considering a population readout.Another level of complexity is that downstream areas must use this sensory code flexibly in perceptual decision making. Many neurons and areas can contain the information about the sensory stimulus, and the readout should correspond to the experience of the animal. This thesis investigates these issues in order. In chapter 2, I determine the neural basis for a type of contextual modulation in our motion perception, the worsening of motion perception at large stimulus size. Large stimuli suppress the firing rate of neurons in a form of contextual modulation known as surround suppression. I simultaneously record from multiple neurons in the middle temporal visual area (MT), and I perform a simulation of the recorded responses and the correlation structure. I find surround suppression improves the population sensitivity for small stimuli at the expense of weaker sensitivity for large stimuli. In chapter 3, I examine the underlying circuitry mechanisms for surround suppression. Recent work suggests that the cortex operates in a theoretical network where excitation alone is strong enough to induce instability but inhibition maintains the stability. I pharmacologically manipulate the efficacy of inhibitory processes and find that the neuronal dynamics are consistent with the predictions. I then perform additional experiments to confirm that this network mechanism can be generalized to different stimulus dimensions in MT. In chapter 4, I examine the flexibility of the readout of sensory information. The readout of sensory evidence for visual perception is plastic and depends on recent training experience. I use reversible inactivation and microstimulation to probe the causal relationship between MT neuronal response and perception. I find the causal contribution of MT to visual motion perception depends on training the animals on a specific task of motion integration. This thesis has implications in the broader context of neural coding in health and diseases. Previous work shows that natural aging or disease processes can lead to deficits in our sensory perception, and the reduction of inhibition efficacy has been implicated. Therefore, an understanding of the inhibitory interactions in local cortical circuitry may lead to future treatments and interventions." --
Opioid Receptor Mediated Modulation Of Spinal Neuronal Responses To Natural Peripheral Stimulation
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Author : Christopher Graham Parsons
language : en
Publisher:
Release Date : 1987
Opioid Receptor Mediated Modulation Of Spinal Neuronal Responses To Natural Peripheral Stimulation written by Christopher Graham Parsons and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with categories.
Effects Of Iontophoretically Administered Norepinephrine In Cat Somatosensory Cortex
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Author : Richard Warren
language : en
Publisher:
Release Date : 1990
Effects Of Iontophoretically Administered Norepinephrine In Cat Somatosensory Cortex written by Richard Warren and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.
"Pharmacological evidence suggests that the inhibitions were mediated by $ alpha sb{2}$- and $ beta$-receptors while the excitations and the long-lasting increases in neuronal activity were mediated by $ alpha sb1$-receptors." --
The Dynamic Brain
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Author : Mingzhou Ding
language : en
Publisher: Oxford University Press, USA
Release Date : 2011
The Dynamic Brain written by Mingzhou Ding and has been published by Oxford University Press, USA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with Medical categories.
Theoretical, experimental and clinical perspectives. Readership: Graduate students, postdocs and research scientists in Neuroscience.
State Dependent Cortical Processing
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Author : Michael Goard
language : en
Publisher:
Release Date : 2009
State Dependent Cortical Processing written by Michael Goard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The nucleus basalis of the basal forebrain is an essential component of the neuromodulatory system controlling the behavioral state of an animal, and it is thought to play key roles in regulating arousal and attention. However, the effect of NB activation on sensory processing remains poorly understood. Using polytrode recording in rat visual cortex, we show that NB stimulation causes prominent decorrelation between neurons and marked improvement in the reliability of neuronal responses to natural scenes. The decorrelation depends on local activation of cortical muscarinic acetylcholine receptors, while the increased reliability involves distributed neural circuits, as evidenced by NB-induced changes in thalamic responses. Further analysis showed that the decorrelation and increased reliability improve cortical representation of natural stimuli in a complementary manner. Thus, the basal forebrain neuromodulatory circuit, which is known to be activated during aroused and attentive states, acts through both local and distributed mechanisms to improve sensory coding.