WHEN THE visual cortex in the occipital lobe is electrically
... psychophysical descriptions of phosphenes produced by a wide range of temporo-spatial patterns of electrical stimulation; The studies described here provide general guidelines for the typical specifications of intracortical electrode arrays, including penetration depth and tip spacing. It seems like ...
... psychophysical descriptions of phosphenes produced by a wide range of temporo-spatial patterns of electrical stimulation; The studies described here provide general guidelines for the typical specifications of intracortical electrode arrays, including penetration depth and tip spacing. It seems like ...
Event-Related Potentials
... cerebral cortex. Understanding the neural basis of cognition therefore will likely require knowledge of cortical operations at all organizational levels, which may usefully be grouped as microscopic, mesoscopic, and macroscopic. The cellular mechanisms of cortical neurons operate at the microscopic ...
... cerebral cortex. Understanding the neural basis of cognition therefore will likely require knowledge of cortical operations at all organizational levels, which may usefully be grouped as microscopic, mesoscopic, and macroscopic. The cellular mechanisms of cortical neurons operate at the microscopic ...
Modulation of early cortical processing during divided attention to
... owing to the low temporal resolution of the methods employed, these studies are not suitable for investigating whether or not any cost involved in splitting the spotlight might impact on the precise temporal locus of attention, i.e. whether the modulation might occur during initial feedforward proce ...
... owing to the low temporal resolution of the methods employed, these studies are not suitable for investigating whether or not any cost involved in splitting the spotlight might impact on the precise temporal locus of attention, i.e. whether the modulation might occur during initial feedforward proce ...
(2006) Changes in visual receptive fields with microstimulation of
... has been described in terms of its effect on the structure of receptive fields (RFs), where multiple stimuli compete to drive neural responses and ultimately behavior. We stimulated the frontal eye field (FEF) of passively fixating monkeys and produced changes in V4 responses similar to known effect ...
... has been described in terms of its effect on the structure of receptive fields (RFs), where multiple stimuli compete to drive neural responses and ultimately behavior. We stimulated the frontal eye field (FEF) of passively fixating monkeys and produced changes in V4 responses similar to known effect ...
Science - Princeton University
... show the only direction of horizontal movement of this stimulus which would elicit a response. Vertical movement had no effect. Within each eye, stimulation of the area labeled with a solid arrow gave a stronger response than that labeled with the dotted arrows; L, directional preference of left eye ...
... show the only direction of horizontal movement of this stimulus which would elicit a response. Vertical movement had no effect. Within each eye, stimulation of the area labeled with a solid arrow gave a stronger response than that labeled with the dotted arrows; L, directional preference of left eye ...
Perceptual Expectation Evokes Category
... temporal cueing or expectation also facilitates visual perception (e.g., Correa et al. 2005; for review, see Nobre et al. 2007). The neural mechanisms of spatial and feature-based visual expectation have been studied extensively. For example, directing attention to a location in anticipation of a ta ...
... temporal cueing or expectation also facilitates visual perception (e.g., Correa et al. 2005; for review, see Nobre et al. 2007). The neural mechanisms of spatial and feature-based visual expectation have been studied extensively. For example, directing attention to a location in anticipation of a ta ...
Preattentive Filling-in of Visual Surfaces in Parietal Extinction
... particular interest because they provide examples of the visual system going beyond the immediate retinal image, toward an interpretation of the probable three-dimensional (3D) sources in the external world ...
... particular interest because they provide examples of the visual system going beyond the immediate retinal image, toward an interpretation of the probable three-dimensional (3D) sources in the external world ...
CATEGORIES IN THE PIGEON BRAIN - Ruhr-Universität
... (Kriegeskorte et al., 2008). Hence, categorical ...
... (Kriegeskorte et al., 2008). Hence, categorical ...
Vigabatrin: The Problem of Monitoring for Peripheral Vision Loss in
... Vigabatrin has been used around the world to treat epilepsy since the early 1990’s and has recently been approved for use in the United States. Vigabatrin is approved for the management of refractory, complex partial seizures in adults who have failed a number of other anti-epileptic drugs. However ...
... Vigabatrin has been used around the world to treat epilepsy since the early 1990’s and has recently been approved for use in the United States. Vigabatrin is approved for the management of refractory, complex partial seizures in adults who have failed a number of other anti-epileptic drugs. However ...
Neural correlates of attention in primate visual cortex
... effects in the presumed human homolog31–33. By now, imaging studies had traced these attentional effects on motion processing all the way back to V1 (Refs 34,35). Taken together, these studies demonstrate that attention influences processing in both pathways from the beginning, but they also indicat ...
... effects in the presumed human homolog31–33. By now, imaging studies had traced these attentional effects on motion processing all the way back to V1 (Refs 34,35). Taken together, these studies demonstrate that attention influences processing in both pathways from the beginning, but they also indicat ...
T2 - Center for Neural Basis of Cognition
... classical receptive field. Vision is an active process of building representations. ...
... classical receptive field. Vision is an active process of building representations. ...
Slide 1
... May be that attentional mechanisms can modulate the responses of MT neurons more effectively with reference to a combination of direction and space (Treue and Maunsell) than to space alone (this study) • Feature-based attentional mechanisms (direction of motion as feature) may contribute to the a ...
... May be that attentional mechanisms can modulate the responses of MT neurons more effectively with reference to a combination of direction and space (Treue and Maunsell) than to space alone (this study) • Feature-based attentional mechanisms (direction of motion as feature) may contribute to the a ...
Document
... pinholes and holding them in exact coincidence, and yet at the same time he can concentrate his attention on any part of the dark field he likes, so that when the spark comes, he will get an impression about objects in that particular region only. In this experiment the attention is entirely indepen ...
... pinholes and holding them in exact coincidence, and yet at the same time he can concentrate his attention on any part of the dark field he likes, so that when the spark comes, he will get an impression about objects in that particular region only. In this experiment the attention is entirely indepen ...
Visual field defect
... Papillitis >> inflammation of the anterior optic nerve causes disc swelling, and sometimes hemorrhages, cells in the vitreous, and deep retinal exudates. After the neuritis resolves, the disc is often pale (optic pallor), most commonly in the temporal aspect. Atrophy is seen over time, especially af ...
... Papillitis >> inflammation of the anterior optic nerve causes disc swelling, and sometimes hemorrhages, cells in the vitreous, and deep retinal exudates. After the neuritis resolves, the disc is often pale (optic pallor), most commonly in the temporal aspect. Atrophy is seen over time, especially af ...
GABA-antagonist inverts movement and object detection in flies
... the stimuli were displaled in intervals of 10 s. The direction-specific response (R,,) drops dramatically after pressure-injection of 1-5 pmol picrotoxinin into the brain and then recovers within 15-45 min (average of 6 tlies in Fig. 2a). Some tlies show in the recovery period a slightly higher resp ...
... the stimuli were displaled in intervals of 10 s. The direction-specific response (R,,) drops dramatically after pressure-injection of 1-5 pmol picrotoxinin into the brain and then recovers within 15-45 min (average of 6 tlies in Fig. 2a). Some tlies show in the recovery period a slightly higher resp ...
- Stem-cell and Brain Research Institute
... (Falchier, Clavagnier, Barone, & Kennedy, 2002). Multisensory integration of sensory inputs has been shown to occur at multiple sites, including midbrain and cortical levels (Stein & Meredith, 1993). Multisensory convergence is not a sufficient condition for multisensory integration. At the level of ...
... (Falchier, Clavagnier, Barone, & Kennedy, 2002). Multisensory integration of sensory inputs has been shown to occur at multiple sites, including midbrain and cortical levels (Stein & Meredith, 1993). Multisensory convergence is not a sufficient condition for multisensory integration. At the level of ...
The Problem of Consciousness by Francis Crick and
... V I S U A L T H E O R I S T S A G R E E that the problem of visual consciousness is ill posed. The mathematical term “ill posed” means that additional constraints are needed to solve the problem. Although the main function of the visual system is to perceive objects and events in the world around us ...
... V I S U A L T H E O R I S T S A G R E E that the problem of visual consciousness is ill posed. The mathematical term “ill posed” means that additional constraints are needed to solve the problem. Although the main function of the visual system is to perceive objects and events in the world around us ...
31 - UCL
... visuotopic organization (e.g., mirror-image or non-mirror-image map of hemifield, bounding areas, pattern of map discontinuities, degree of retinotopy), and physiological properties (e.g., excitatory receptive field size, direction selectivity, attention-related modulation). Areas differ in the degr ...
... visuotopic organization (e.g., mirror-image or non-mirror-image map of hemifield, bounding areas, pattern of map discontinuities, degree of retinotopy), and physiological properties (e.g., excitatory receptive field size, direction selectivity, attention-related modulation). Areas differ in the degr ...
Responses to Rare Visual Target and Distractor Stimuli Using Event
... 1997; Knight and Nakada 1998). This suggests that some portion of the neural activity evoked by these stimuli is not observed using fMRI. In a previous study (Clark et al. 1998), we introduced a method for performing event-related fMRI using multiple regression, which has shown greater sensitivity t ...
... 1997; Knight and Nakada 1998). This suggests that some portion of the neural activity evoked by these stimuli is not observed using fMRI. In a previous study (Clark et al. 1998), we introduced a method for performing event-related fMRI using multiple regression, which has shown greater sensitivity t ...
Visual and oculomotor selection: links, causes and
... visual responses in V4 neurons at retinotopically corresponding locations, whereas responses at other locations were suppressed. Interestingly, both the enhancement and suppression effects depended on the presence of additional ‘distracter’ stimuli outside the V4 neuron receptive field, as has been ...
... visual responses in V4 neurons at retinotopically corresponding locations, whereas responses at other locations were suppressed. Interestingly, both the enhancement and suppression effects depended on the presence of additional ‘distracter’ stimuli outside the V4 neuron receptive field, as has been ...
Can neuroscience reveal the true nature of consciousness?
... definition, accordingly refine its neural correlate1 , and thus spiral down towards a full understanding of consciousness. There are some major problems with this approach: 1. If consciousness will in part be defined by its neural correlate, there is a circularity in proving that particular neural ...
... definition, accordingly refine its neural correlate1 , and thus spiral down towards a full understanding of consciousness. There are some major problems with this approach: 1. If consciousness will in part be defined by its neural correlate, there is a circularity in proving that particular neural ...
5. Discussion - UvA-DARE - University of Amsterdam
... broadened, potentially to amplify the summed V1 output for the conditioned stimuli. It has to be emphasized here that the orientation discrimination in chapter 2 was between stimuli differing 90 degrees in orientation, which already leads to very different response patterns in the visual cortex in u ...
... broadened, potentially to amplify the summed V1 output for the conditioned stimuli. It has to be emphasized here that the orientation discrimination in chapter 2 was between stimuli differing 90 degrees in orientation, which already leads to very different response patterns in the visual cortex in u ...
The Physiology of the Senses Lecture 6 Visually Guided Actions
... 3) The parietal and prefrontal areas are involved in covert shifts in attention. As we have seen, the PEF through the FEF directs saccades to locations of interest. These are overt shifts of attention. The two areas are also involved in covert shifts of attention. Because covert shifts can redirect ...
... 3) The parietal and prefrontal areas are involved in covert shifts in attention. As we have seen, the PEF through the FEF directs saccades to locations of interest. These are overt shifts of attention. The two areas are also involved in covert shifts of attention. Because covert shifts can redirect ...
Visuospatial processing and the right
... speech and dominates language functions, has greater fine motor control, and superior cognitive abilities in general. Split-brain researchers have suggested that the left hemisphere often over-rules the right, even when it does not possess task-relevant information, and that it is ‘‘in control’’ most ...
... speech and dominates language functions, has greater fine motor control, and superior cognitive abilities in general. Split-brain researchers have suggested that the left hemisphere often over-rules the right, even when it does not possess task-relevant information, and that it is ‘‘in control’’ most ...
Feedforward, horizontal, and feedback processing
... We (VAF Lamme, K Zipser, H Spekreijse, Invest Ophthalmol Vis Sci 1997, 38:S969; VAF Lamme, K Zipser, H Spekreijse, Soc Neurosci Abstr 1997, 23:603.1) have studied the role of feedback in the awake macaque. It was previously shown that V1 responses to texture elements are enhanced when these belong t ...
... We (VAF Lamme, K Zipser, H Spekreijse, Invest Ophthalmol Vis Sci 1997, 38:S969; VAF Lamme, K Zipser, H Spekreijse, Soc Neurosci Abstr 1997, 23:603.1) have studied the role of feedback in the awake macaque. It was previously shown that V1 responses to texture elements are enhanced when these belong t ...
P200
In neuroscience, the visual P200 or P2 is a waveform component or feature of the event-related potential (ERP) measured at the human scalp. Like other potential changes measurable from the scalp, this effect is believed to reflect the post-synaptic activity of a specific neural process. The P2 component, also known as the P200, is so named because it is a positive going electrical potential that peaks at about 200 milliseconds (varying between about 150 and 275 ms) after the onset of some external stimulus . The distribution of this component in the brain, as measured by electrodes placed across the scalp, is located around the centro-frontal and the parieto-occipital region. It is generally found to be maximal around the vertex (frontal region) of the scalp, however there have been some topographical differences noted in ERP studies of the P2 in different experimental conditions.Research on the visual P2 is at an early stage compared to other more established ERP components and there is much that we still do not know about it. Part of the difficulty of clearly characterizing this component is that it appears to be modulated by a large and diverse number of cognitive tasks. Functionally, there seems to be partial agreement amongst researchers in the field of cognitive neuroscience that the P2 represents some aspect of higher-order perceptual processing, modulated by attention. It is known that the P2 is typically elicited as part of the normal response to visual stimuli and has been studied in relation to visual search and attention, language context information, and memory and repetition effects. The amplitude of the peak of the waveform may be modulated by many different aspects of visual stimuli, which allow it to be used for studies of visual cognition and disease. In general, the P2 may be a part of cognitive matching system that compares sensory inputs with stored memory.