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A Novel Critical Period for Inhibitory Plasticity in Rat Somatosensory Cortex

A Novel Critical Period for Inhibitory Plasticity in Rat Somatosensory Cortex PDF Author: Renna J. Stevens
Publisher:
ISBN: 9781124406831
Category :
Languages : en
Pages : 74

Book Description
The cerebral cortex encodes sensory information with astonishing precision, but it is also confronted with the impressive task of reworking and rewiring its physiology in the face of a changing environment. Hubel and Weisel first characterized the impact of sensory deprivation on the development of cortical response properties, but there is still much we do not know about which forms of cortical plasticity are induced with sensory deprivation, as well as which cell types and synapses mediate plasticity. While traditional models of cortical plasticity proposed Hebbian ("use it or lose it") rules in excitatory circuits as the primary substrate for cortical plasticity, recent advances to the classical model include an important role for non-Hebbian forms of plasticity, and show that inhibitory circuits are a major site of sensory plasticity. A precisely regulated balance between cortical excitation and inhibition is crucial for sensory processing and plasticity, but our understanding of inhibitory synapse development is lacking. Here we investigate the impact of sensory experience on the development and function of inhibitory synapses in rat primary somatosensory cortex. I deprived the D-row of rat whiskers (beginning on the 7th postnatal day, P7) in order to probe how experience guides inhibitory synapse development. I found that deprivation reduced inhibitory currents at P15 in layer (L) 4 and at P21 in L2/3. Evoked inhibition was also reduced at P15 in L4. This reduction in inhibition constitutes a homeostatic form of plasticity, as it would ultimately increase excitatory activity in response to sensory deprivation. Surprisingly, inhibitory currents recovered to control (spared) levels after this one-day period. Our findings demonstrate that the development of inhibitory signaling in S1 during the first postnatal month occurs in a largely experience-independent fashion, but that sensory deprivation during this period causes a delayed and transient reduction in the efficacy of inhibitory signaling. Our results also reveal that these transient changes in mIPSC amplitude and frequency can be dissociated, meaning that they are mechanistically independent. These results add to the growing body of evidence that inhibitory circuits undergo homeostatic plasticity in response to sensory use and disuse in primary sensory cortex.

A Novel Critical Period for Inhibitory Plasticity in Rat Somatosensory Cortex

A Novel Critical Period for Inhibitory Plasticity in Rat Somatosensory Cortex PDF Author: Renna J. Stevens
Publisher:
ISBN: 9781124406831
Category :
Languages : en
Pages : 74

Book Description
The cerebral cortex encodes sensory information with astonishing precision, but it is also confronted with the impressive task of reworking and rewiring its physiology in the face of a changing environment. Hubel and Weisel first characterized the impact of sensory deprivation on the development of cortical response properties, but there is still much we do not know about which forms of cortical plasticity are induced with sensory deprivation, as well as which cell types and synapses mediate plasticity. While traditional models of cortical plasticity proposed Hebbian ("use it or lose it") rules in excitatory circuits as the primary substrate for cortical plasticity, recent advances to the classical model include an important role for non-Hebbian forms of plasticity, and show that inhibitory circuits are a major site of sensory plasticity. A precisely regulated balance between cortical excitation and inhibition is crucial for sensory processing and plasticity, but our understanding of inhibitory synapse development is lacking. Here we investigate the impact of sensory experience on the development and function of inhibitory synapses in rat primary somatosensory cortex. I deprived the D-row of rat whiskers (beginning on the 7th postnatal day, P7) in order to probe how experience guides inhibitory synapse development. I found that deprivation reduced inhibitory currents at P15 in layer (L) 4 and at P21 in L2/3. Evoked inhibition was also reduced at P15 in L4. This reduction in inhibition constitutes a homeostatic form of plasticity, as it would ultimately increase excitatory activity in response to sensory deprivation. Surprisingly, inhibitory currents recovered to control (spared) levels after this one-day period. Our findings demonstrate that the development of inhibitory signaling in S1 during the first postnatal month occurs in a largely experience-independent fashion, but that sensory deprivation during this period causes a delayed and transient reduction in the efficacy of inhibitory signaling. Our results also reveal that these transient changes in mIPSC amplitude and frequency can be dissociated, meaning that they are mechanistically independent. These results add to the growing body of evidence that inhibitory circuits undergo homeostatic plasticity in response to sensory use and disuse in primary sensory cortex.

Inhibitory Synaptic Plasticity

Inhibitory Synaptic Plasticity PDF Author: Melanie A. Woodin
Publisher: Springer Science & Business Media
ISBN: 1441969780
Category : Medical
Languages : en
Pages : 191

Book Description
This volume will explore the most recent findings on cellular mechanisms of inhibitory plasticity and its functional role in shaping neuronal circuits, their rewiring in response to experience, drug addiction and in neuropathology. Inhibitory Synaptic Plasticity will be of particular interest to neuroscientists and neurophysiologists.

Developmental Plasticity of Inhibitory Circuitry

Developmental Plasticity of Inhibitory Circuitry PDF Author: Sarah L. Pallas
Publisher: Springer
ISBN: 1441912436
Category : Medical
Languages : en
Pages : 192

Book Description
Neuroscience has long been focused on understanding neural plasticity in both development and adulthood. Experimental work in this area has focused almost entirely on plasticity at excitatory synapses. A growing body of evidence suggests that plasticity at inhibitory GABAergic and glycinergic synapses is of critical importance during both development and aging. The book brings together the work of researchers investigating inhibitory plasticity at many levels of analysis and in several different preparations. This topic is of wide relevance across a number of different areas of research in neuroscience and neurology. Medical problems such as epilepsy, mental illness, drug abuse, and movement disorders can result from malfunctioning inhibitory circuits. Further, the maturation of inhibitory circuits may trigger the onset of critical periods of neural circuit plasticity, raising the possibility that such plastici periods could be reactivated for medical benefit by manipulating inhibitory circuitry.

Inhibitory Regulation of Plasticity Across the Lifespan in the Rat Primary Auditory Cortex

Inhibitory Regulation of Plasticity Across the Lifespan in the Rat Primary Auditory Cortex PDF Author: Jose Miguel Cisneros-Franco
Publisher:
ISBN:
Category :
Languages : en
Pages :

Book Description
"Neuroplasticity refers to the brain’s ability to modify its connections and function in response to experience. This experience-dependent plasticity is necessary for the acquisition of new abilities during early development or in adult life, and plays a crucial role in recovery after a neurological injury. During early developmental epochs known as critical periods (CPs), passive experience alone can have profound and long-lasting effects in cortical sensory representations. In contrast, plasticity in the adult brain occurs almost exclusively in the context of perceptual learning (PL); i.e., the process whereby attention and repetition lead to long-lasting improvements in stimulus detection or sensory discrimination.Whether it occurs as a result of passive experience, PL, or other experimental interventions, cortical plasticity ultimately entails a change in activity patterns driven by a shift in the local levels of excitation and inhibition. And although cortical inhibitory interneurons constitute a clear minority compared to the number of excitatory neurons, they are instrumental in regulating both juvenile and adult experience-dependent plasticity. This thesis consists of three experimental studies that addressed critical and interrelated knowledge gaps regarding the inhibitory regulating mechanisms of experience-dependent plasticity, both in the context of changes in the environment and during PL. Using the rat primary auditory cortex (A1) as a model, we combined electrophysiological, anatomical, chemogenetic, and behavioral methodologies to address each study’s main hypotheses. In the first study we examined the role of inhibition in A1 plasticity across the lifespan. We found that reduced cortical inhibition in older adults was associated with an increased but poorly regulated plasticity when compared to younger adults. In older brains, however, changes elicited by auditory stimulation and training were rapidly lost, suggesting that such increased plasticity might be detrimental, as the older brains were unable to consolidate these changes. Importantly, increasing inhibition artificially with clinically available drugs restored the stability of sensory representations and improved the retention of plastic changes associated with PL.In the second study, we turned our attention to parvalbumin-positive (PV+) cells, the most common type of inhibitory neurons in the brain. Bidirectional manipulation of PV+ cell activity affected neuronal spectral and sound intensity selectivity, and, in the case of PV+ interneuron inactivation, was mirrored by anatomical changes in PV and associated perineuronal net expression. In addition, we showed that the inactivation of PV+ interneurons is sufficient to reinstate CP plasticity in the adult auditory cortex. In the third study, we investigated the role of PV+ cells in auditory PL. As previously reported in other cortical areas, training was associated with a transient downregulation of PV expression during early stages of training. We then examined the effects of prolonged PV+ cell manipulation throughout the training period. Our results suggest that, although reduced PV+ cell function may facilitate early training-related modifications in cortical circuits, a subsequent increase in PV+ cell activity is needed to prevent further plastic changes and consolidate learning. Taken together, our findings underscore the importance of sustained inhibitory neurotransmission in ensuring high fidelity discrimination of sensory inputs and in maintaining the stability of sensory representations. Our behavioral studies further suggest that such stability is necessary for the consolidation of complex skills that are built on basic sensory representations. Finally, the experimental work presented in this thesis also highlights the potential of pharmacological and chemogenetic approaches for harnessing cortical plasticity with the ultimate goal of aiding recovery from brain injury or disease"--

Development of Sensory Systems in Mammals

Development of Sensory Systems in Mammals PDF Author: James R. Coleman
Publisher: Wiley-Interscience
ISBN:
Category : Medical
Languages : en
Pages : 664

Book Description
Reviews the state of knowledge on the mechanisms of development of mammalian sensory systems and presents new findings on genetically controlled and environmentally contingent patterns of sensory system development. Also reveals major principles deduced from studies of the developing visual, auditory, somatosensory, and chemical sensory systems that are generalizable to other regions of the developing nervous system, and provides insights on the comparative development of sensory system structure and function among mammals, including humans.

Molecular and Cellular Neurobiology

Molecular and Cellular Neurobiology PDF Author: S. Prasad
Publisher: Alpha Science Int'l Ltd.
ISBN: 9788173195822
Category : Medical
Languages : en
Pages : 338

Book Description
Presents an account of the remarkable progress made in different areas of neurobiology. This book introduces the structure and development of the brain, showing how they are specialized for the functions they serve. It is concerned with hormones and neurotransmitters.

Cognitive Plasticity in Neurologic Disorders

Cognitive Plasticity in Neurologic Disorders PDF Author: Joseph I. Tracy
Publisher: Oxford University Press, USA
ISBN: 0199965242
Category : Medical
Languages : en
Pages : 433

Book Description
This volume makes clear that the cognitive and behavioural symptoms of neurologic disorders and syndromes are dynamic and changing. Each chapter describes the neuroplastic processes at work in a particular condition, giving rise to these ongoing cognitive changes.

Excitatory-Inhibitory Balance

Excitatory-Inhibitory Balance PDF Author: Takao K. Hensch
Publisher: Springer Science & Business Media
ISBN: 9780306479625
Category : Medical
Languages : en
Pages : 314

Book Description
A new perspective on brain function depends upon an understanding of the interaction and integration of excitation and inhibition. A recent surge in research activity focused on inhibitory interneurons now makes a more balanced view possible. Technological advances such as improved imaging methods, visualized patch-clamp recording, multiplex single-cell PCR, and gene-targeted deletion or knock-in mice are some of the novel tools featured in this book. This book will provide an integrated view of neuron function, operating in a balanced regime of excitation and inhibition. It is a timely contribution emphasizing how this balance is established, maintained, and modified from the molecular to system levels. The broad spectrum of topics from molecular to cellular and system/computational neuroscience will appeal to a wide audience of advanced graduate students, post-docs, and faculty. Moreover, this book this book features active young researchers from around the world, who are currently educating the brain scientists of tomorrow.

Micro-, Meso- and Macro-Connectomics of the Brain

Micro-, Meso- and Macro-Connectomics of the Brain PDF Author: Henry Kennedy
Publisher: Springer
ISBN: 3319277774
Category : Medical
Languages : en
Pages : 173

Book Description
This book has brought together leading investigators who work in the new arena of brain connectomics. This includes ‘macro-connectome’ efforts to comprehensively chart long-distance pathways and functional networks; ‘micro-connectome’ efforts to identify every neuron, axon, dendrite, synapse, and glial process within restricted brain regions; and ‘meso-connectome’ efforts to systematically map both local and long-distance connections using anatomical tracers. This book highlights cutting-edge methods that can accelerate progress in elucidating static ‘hard-wired’ circuits of the brain as well as dynamic interactions that are vital for brain function. The power of connectomic approaches in characterizing abnormal circuits in the many brain disorders that afflict humankind is considered. Experts in computational neuroscience and network theory provide perspectives needed for synthesizing across different scales in space and time. Altogether, this book provides an integrated view of the challenges and opportunities in deciphering brain circuits in health and disease.

The Auditory Cortex

The Auditory Cortex PDF Author: Jeffery A. Winer
Publisher: Springer Science & Business Media
ISBN: 1441900748
Category : Science
Languages : en
Pages : 711

Book Description
There has been substantial progress in understanding the contributions of the auditory forebrain to hearing, sound localization, communication, emotive behavior, and cognition. The Auditory Cortex covers the latest knowledge about the auditory forebrain, including the auditory cortex as well as the medial geniculate body in the thalamus. This book will cover all important aspects of the auditory forebrain organization and function, integrating the auditory thalamus and cortex into a smooth, coherent whole. Volume One covers basic auditory neuroscience. It complements The Auditory Cortex, Volume 2: Integrative Neuroscience, which takes a more applied/clinical perspective.