Author: Nayan Chanauria
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In the cat primary visual cortex (V1 or area17), neurons fundamentally respond to orientations of the objects in the outside world. Neurons responding to specific orientations form the orientation columns in V1. A neuron responding to a horizontal orientation will get optimally excited towards the outline of a horizontal object. This feature of the visual cortex known as orientation selectivity has been continuously explored to study the effects of adaptation. Following a training paradigm called adaptation, the same neuron that was inherently responding to the horizontal orientation will respond to an oblique orientation. In this thesis, we seek to examine the orientation tuning properties of individual neurons in superficial and deeper layers of V1 in different adaptation environments. Due to the extensive interconnectivity between V1 neurons, we hypothesize that not only do individual neurons get affected by adaptation paradigm, but the whole cortex is reprogramed. To this aim, extracellular recordings were performed in conventionally prepared anesthetized cats. Neural activities were recorded simultaneously from layer 2/3 and layer 5/6 using a tungsten multichannel electrode. Neurons were adapted with a visual adapter (visual adaptation) and a repetitive sound (sound adaptation) in two different settings. Both types of adaptations were performed uninterrupted for 12 minutes. In both settings, sine-wave drifting gratings were presented to evoke responses in V1 and generate tuning curves from the recorded multiunit activity. The functional connectivity between the recorded neurons was revealed by computing cross-correlation between individual neuron pairs. In response to visual adaptation, layer 2/3 and 5/6 neurons displayed classical attractive and repulsive shifts. On comparing the behaviour of the neurons in either layer, an equivalent tendency was observed. Cross-correlograms between the spike trains of neurons in layers 2/3 and 5/6 revealed synchronized firing between the neurons suggesting coordinated dynamics of the co-active neurons and their functional connections. During sound adaptation, where the visual adapter was completely absent, shifts in the tuning curves were observed in either layer indicating a novel orientation selectivity. However, it is noteworthy that cells in both layers shifted in opposite directions indicating independent behaviour. V1 neurons might have an additional role besides processing visual stimuli. The visual neurons may have demonstrated multisensory properties when stimulated indirectly through neighbouring sensory regions. Our results indicate that primary visual neurons can be evoked by direct or indirect stimulation. The difference in the responses of layer 2/3 and layer 5/6 neurons towards the different adaptation environments indicate that neurons in V1 may behave similar or different towards the different sensory stimulus. This suggests that V1 responses are stimulus dependent. Additionally, the synchronized firing of layer 2/3 and layer 5/6 neurons towards visual adapter signify an existence of functional connectivity between the neuron pairs. Together, it can be summarised that visual neurons undergo an alteration of selectivity by building new orientation maps that ultimately potentiates plasticity within sensory regions that are highly suggestive of entire cortex being multisensory.
Investigating the Comparative Effects of Adaptation on Supra and Infragranular Layers with Visual and Acoustic Stimulation in Cat's Visual Cortex
Author: Nayan Chanauria
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In the cat primary visual cortex (V1 or area17), neurons fundamentally respond to orientations of the objects in the outside world. Neurons responding to specific orientations form the orientation columns in V1. A neuron responding to a horizontal orientation will get optimally excited towards the outline of a horizontal object. This feature of the visual cortex known as orientation selectivity has been continuously explored to study the effects of adaptation. Following a training paradigm called adaptation, the same neuron that was inherently responding to the horizontal orientation will respond to an oblique orientation. In this thesis, we seek to examine the orientation tuning properties of individual neurons in superficial and deeper layers of V1 in different adaptation environments. Due to the extensive interconnectivity between V1 neurons, we hypothesize that not only do individual neurons get affected by adaptation paradigm, but the whole cortex is reprogramed. To this aim, extracellular recordings were performed in conventionally prepared anesthetized cats. Neural activities were recorded simultaneously from layer 2/3 and layer 5/6 using a tungsten multichannel electrode. Neurons were adapted with a visual adapter (visual adaptation) and a repetitive sound (sound adaptation) in two different settings. Both types of adaptations were performed uninterrupted for 12 minutes. In both settings, sine-wave drifting gratings were presented to evoke responses in V1 and generate tuning curves from the recorded multiunit activity. The functional connectivity between the recorded neurons was revealed by computing cross-correlation between individual neuron pairs. In response to visual adaptation, layer 2/3 and 5/6 neurons displayed classical attractive and repulsive shifts. On comparing the behaviour of the neurons in either layer, an equivalent tendency was observed. Cross-correlograms between the spike trains of neurons in layers 2/3 and 5/6 revealed synchronized firing between the neurons suggesting coordinated dynamics of the co-active neurons and their functional connections. During sound adaptation, where the visual adapter was completely absent, shifts in the tuning curves were observed in either layer indicating a novel orientation selectivity. However, it is noteworthy that cells in both layers shifted in opposite directions indicating independent behaviour. V1 neurons might have an additional role besides processing visual stimuli. The visual neurons may have demonstrated multisensory properties when stimulated indirectly through neighbouring sensory regions. Our results indicate that primary visual neurons can be evoked by direct or indirect stimulation. The difference in the responses of layer 2/3 and layer 5/6 neurons towards the different adaptation environments indicate that neurons in V1 may behave similar or different towards the different sensory stimulus. This suggests that V1 responses are stimulus dependent. Additionally, the synchronized firing of layer 2/3 and layer 5/6 neurons towards visual adapter signify an existence of functional connectivity between the neuron pairs. Together, it can be summarised that visual neurons undergo an alteration of selectivity by building new orientation maps that ultimately potentiates plasticity within sensory regions that are highly suggestive of entire cortex being multisensory.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
In the cat primary visual cortex (V1 or area17), neurons fundamentally respond to orientations of the objects in the outside world. Neurons responding to specific orientations form the orientation columns in V1. A neuron responding to a horizontal orientation will get optimally excited towards the outline of a horizontal object. This feature of the visual cortex known as orientation selectivity has been continuously explored to study the effects of adaptation. Following a training paradigm called adaptation, the same neuron that was inherently responding to the horizontal orientation will respond to an oblique orientation. In this thesis, we seek to examine the orientation tuning properties of individual neurons in superficial and deeper layers of V1 in different adaptation environments. Due to the extensive interconnectivity between V1 neurons, we hypothesize that not only do individual neurons get affected by adaptation paradigm, but the whole cortex is reprogramed. To this aim, extracellular recordings were performed in conventionally prepared anesthetized cats. Neural activities were recorded simultaneously from layer 2/3 and layer 5/6 using a tungsten multichannel electrode. Neurons were adapted with a visual adapter (visual adaptation) and a repetitive sound (sound adaptation) in two different settings. Both types of adaptations were performed uninterrupted for 12 minutes. In both settings, sine-wave drifting gratings were presented to evoke responses in V1 and generate tuning curves from the recorded multiunit activity. The functional connectivity between the recorded neurons was revealed by computing cross-correlation between individual neuron pairs. In response to visual adaptation, layer 2/3 and 5/6 neurons displayed classical attractive and repulsive shifts. On comparing the behaviour of the neurons in either layer, an equivalent tendency was observed. Cross-correlograms between the spike trains of neurons in layers 2/3 and 5/6 revealed synchronized firing between the neurons suggesting coordinated dynamics of the co-active neurons and their functional connections. During sound adaptation, where the visual adapter was completely absent, shifts in the tuning curves were observed in either layer indicating a novel orientation selectivity. However, it is noteworthy that cells in both layers shifted in opposite directions indicating independent behaviour. V1 neurons might have an additional role besides processing visual stimuli. The visual neurons may have demonstrated multisensory properties when stimulated indirectly through neighbouring sensory regions. Our results indicate that primary visual neurons can be evoked by direct or indirect stimulation. The difference in the responses of layer 2/3 and layer 5/6 neurons towards the different adaptation environments indicate that neurons in V1 may behave similar or different towards the different sensory stimulus. This suggests that V1 responses are stimulus dependent. Additionally, the synchronized firing of layer 2/3 and layer 5/6 neurons towards visual adapter signify an existence of functional connectivity between the neuron pairs. Together, it can be summarised that visual neurons undergo an alteration of selectivity by building new orientation maps that ultimately potentiates plasticity within sensory regions that are highly suggestive of entire cortex being multisensory.
Impact of Natural Scenes on the Reliability and Correlations of Cortical Dynamics Across Layers in Cat Primary Visual Cortex
Author: Yannick Passarelli
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The principle of efficient coding suggests that processing in the early visual system should be optimized and adapted to the environmental statistics. An intracellular study of the primary visual cortex (V1) in the anesthetized and paralyzed cat showed that the reliability of the neural response is optimized for natural statistics. Using the same natural and artificial stimuli, we recorded the neuronal population activity (single unit, multi-unit and local field potentials) in cat's V1 with high-density linear silicon probes. We first investigated the reliability and of the mesoscopic signal with the intracellular signal and explored its laminar dependency. Our results showed that natural images evoke, at all scales, the most reliable response, suggesting that V1 is better suited to efficiently encode natural statistics. In addition, granular and infragranular layers displayed higher reliability levels than the supragranular one. This argues for a functional filtering of the pertinent information between these layers. We also explored which statistics of the natural images produce this reliable response. Finally, we specifically addressed the role of the correlations between neurons (within and between layers) by measuring the amount of shared variability and signal of the neuronal population in response to our stimulus set. We observed that natural images always evoked higher correlations. We did not observe a strong decorrelation at the single cell level but instead at the scale of groups of neurons, with those that are close together being more correlated and farther apart less correlated, arguing for a functional clustering of the neurons into coherent “neural mass”.
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
The principle of efficient coding suggests that processing in the early visual system should be optimized and adapted to the environmental statistics. An intracellular study of the primary visual cortex (V1) in the anesthetized and paralyzed cat showed that the reliability of the neural response is optimized for natural statistics. Using the same natural and artificial stimuli, we recorded the neuronal population activity (single unit, multi-unit and local field potentials) in cat's V1 with high-density linear silicon probes. We first investigated the reliability and of the mesoscopic signal with the intracellular signal and explored its laminar dependency. Our results showed that natural images evoke, at all scales, the most reliable response, suggesting that V1 is better suited to efficiently encode natural statistics. In addition, granular and infragranular layers displayed higher reliability levels than the supragranular one. This argues for a functional filtering of the pertinent information between these layers. We also explored which statistics of the natural images produce this reliable response. Finally, we specifically addressed the role of the correlations between neurons (within and between layers) by measuring the amount of shared variability and signal of the neuronal population in response to our stimulus set. We observed that natural images always evoked higher correlations. We did not observe a strong decorrelation at the single cell level but instead at the scale of groups of neurons, with those that are close together being more correlated and farther apart less correlated, arguing for a functional clustering of the neurons into coherent “neural mass”.
Visually Guided Behaviour of Cats in the Absence of Retino-geniculo-cortical Pathways
Author: Kerstin Norrsell
Publisher:
ISBN:
Category : Animal behavior
Languages : en
Pages : 112
Book Description
Publisher:
ISBN:
Category : Animal behavior
Languages : en
Pages : 112
Book Description
A Neurophysiological Investigation of the Feline Extrastriate Visual Cortex (area 18) Using Oriented and Textured Stimuli
Author: J. M. Crook
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
Studies of Primary Visual Cortex and Its Development in Cat and Ferret
Author: Barbara Chapman
Publisher:
ISBN:
Category : Ferret
Languages : en
Pages : 402
Book Description
Publisher:
ISBN:
Category : Ferret
Languages : en
Pages : 402
Book Description
Effects of Vestibular Stimulation on Single Visual Cells in Cat Visual Cortex and Superior Colliculus
Author: Philip A. Schwartzkroin
Publisher:
ISBN:
Category :
Languages : en
Pages : 274
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 274
Book Description
The Cat Primary Visual Cortex
Author: Bertram R. Payne
Publisher:
ISBN: 9780125521048
Category : Medical
Languages : en
Pages : 713
Book Description
Written by experts on the forefront of investigations of brain function, vision, and perception, the material presented is of an unparalleled scientific quality, and shows that analyses of enormous breadth and sophistication are required to probe the structure and function of brain regions. The articles are highly persuasive in showing what can be achieved by carrying out careful and imaginative experiments. The Cat Primary Visual Cortex should emerge as essential reading for all those interested in cerebral cortical processing of visual signals or researching or working in any field of vision. Key Features * Comprehensive account of cat primary visual cortex * Generous use of illustrations including color * Covers research from structure to connections to functions * Chapters by leaders in the field * Topics presneted on multiple, compatible levels
Publisher:
ISBN: 9780125521048
Category : Medical
Languages : en
Pages : 713
Book Description
Written by experts on the forefront of investigations of brain function, vision, and perception, the material presented is of an unparalleled scientific quality, and shows that analyses of enormous breadth and sophistication are required to probe the structure and function of brain regions. The articles are highly persuasive in showing what can be achieved by carrying out careful and imaginative experiments. The Cat Primary Visual Cortex should emerge as essential reading for all those interested in cerebral cortical processing of visual signals or researching or working in any field of vision. Key Features * Comprehensive account of cat primary visual cortex * Generous use of illustrations including color * Covers research from structure to connections to functions * Chapters by leaders in the field * Topics presneted on multiple, compatible levels
The Effect of Dark Adaptation on the Spatial and Temporal Response Characteristics of Single Cells in the Cat Visual Cortex
Author: Arthur Francis Lange
Publisher:
ISBN:
Category : Eye
Languages : en
Pages : 184
Book Description
Publisher:
ISBN:
Category : Eye
Languages : en
Pages : 184
Book Description
Correlated firing of neurons in the cat primary visual cortex
Author: Erik Jan Aarnoutse
Publisher: Cuvillier Verlag
ISBN: 9783898737210
Category :
Languages : de
Pages : 129
Book Description
Publisher: Cuvillier Verlag
ISBN: 9783898737210
Category :
Languages : de
Pages : 129
Book Description
Currents of the Visual Cortex in the Cat
Author: Wolfgang Köhler
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 43
Book Description