Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
72,663
result(s) for
"visual perception."
Sort by:
Cortical layer–specific critical dynamics triggering perception
How are behaviorally relevant representations of the outside world initiated and manifested in the mammalian brain? Marshel et al. combined a channelrhodopsin with an improved holographic stimulation technique to examine activity in the mouse visual cortex, including its deep layers. Optogenetic stimulation of neurons previously activated by natural visual stimuli recreated the original activity and behavior. Neuronal population activity typically propagated from cortical layer 2/3 to layer 5 rather than in the reverse direction. Stimulation of a larger number of cells was required to initiate activity in layer 2/3 than in layer 5. This indicates differences in ensemble coding between the two layers. Science , this issue p. eaaw5202 An optical neural interface reveals the dynamics of cortical network activity underlying mammalian behavior. Perceptual experiences may arise from neuronal activity patterns in mammalian neocortex. We probed mouse neocortex during visual discrimination using a red-shifted channelrhodopsin (ChRmine, discovered through structure-guided genome mining) alongside multiplexed multiphoton-holography (MultiSLM), achieving control of individually specified neurons spanning large cortical volumes with millisecond precision. Stimulating a critical number of stimulus-orientation-selective neurons drove widespread recruitment of functionally related neurons, a process enhanced by (but not requiring) orientation-discrimination task learning. Optogenetic targeting of orientation-selective ensembles elicited correct behavioral discrimination. Cortical layer–specific dynamics were apparent, as emergent neuronal activity asymmetrically propagated from layer 2/3 to layer 5, and smaller layer 5 ensembles were as effective as larger layer 2/3 ensembles in eliciting orientation discrimination behavior. Population dynamics emerging after optogenetic stimulation both correctly predicted behavior and resembled natural internal representations of visual stimuli at cellular resolution over volumes of cortex.
Journal Article
Assessment of Opicinumab in Acute Optic Neuritis Using Multifocal Visual Evoked Potential
Background
Multifocal visual evoked potential (MF-VEP) assesses a wider visual field than full-field VEP (FF-VEP) and potentially offers a more precise analysis of optic nerve injury and repair following optic neuritis. MF-VEP may offer advantages over FF-VEP as an endpoint in clinical trials of remyelinating therapies.
Objective
MF-VEP testing was used to study changes in visual pathways in 48% of RENEW [phase II, opicinumab (anti-LINGO-1; BIIB033) vs. placebo after first acute unilateral optic neuritis] participants.
Methods
This exploratory MF-VEP RENEW substudy compared mean outcomes at weeks 24 and 32 among participants in the intent-to-treat (ITT;
n
= 39; 72% female; mean age: 32.3 years) and per-protocol (PP;
n
= 31; 71% female; mean age: 32.2 years) populations in affected and fellow eye latency from fellow eye baseline latency and affected and fellow eye amplitude from their own baselines. Treatment differences were evaluated using analysis of covariance (week 24) and a mixed-effect model of repeated measures (week 32). Last observation carried forward was used to impute missing data at week 24.
Results
A trend for improvement in affected eye MF-VEP latency with opicinumab versus placebo was seen in the ITT and PP populations at weeks 24 and 32. Both treatment groups in the ITT population experienced partial recovery of amplitude in the affected eye at week 32. Notably, the mean change in fellow eye amplitude at weeks 24 and 32 was − 17.57 and − 31.41 nanovolts (nV) in placebo but only − 0.59 and 1.93 nV in the opicinumab group [differences at weeks 24 and 32: 16.98 nV (
p
= 0.050) and 33.33 nV (
p
< 0.01), respectively].
Conclusion
Results from this substudy showed advantages of MF-VEP over FF-VEP in multicenter studies of central nervous system reparative therapies and provide novel evidence that fellow eye visual pathway amplitude loss occurs after optic neuritis but can potentially be prevented by opicinumab treatment.
Registration
ClinicalTrials.gov identifier NCT01721161.
Journal Article
Deviate : the science of seeing differently
\"Perception is the foundation of human experience, but few of us understand why we see what we do, much less how. By revealing the startling truths about the brain and its perceptions, [neuroscientist] Beau Lotto shows that the next big innovation is not a new technology: it is a new way of seeing. In his first major book, Lotto draws on over two decades of pioneering research to explain that our brain didn't evolve to see the world accurately. It can't! Visually stunning, with entertaining illustrations and optical illusions throughout, and with clear and comprehensive explanations of the science behind how our perceptions operate, Deviate will revolutionize the way you see yourself, others, and the world. With this new understanding of how the brain functions, we can apply these insights to every aspect of life and work. Deviate is not just an illuminating account of the neuroscience of thought, behavior, and creativity: it is a call to action, enlisting readers in their own journey of self-discovery.\"--Jacket.
Book
A neural basis of probabilistic computation in visual cortex
Bayesian models of behavior suggest that organisms represent uncertainty associated with sensory variables. However, the neural code of uncertainty remains elusive. A central hypothesis is that uncertainty is encoded in the population activity of cortical neurons in the form of likelihood functions. We tested this hypothesis by simultaneously recording population activity from primate visual cortex during a visual categorization task in which trial-to-trial uncertainty about stimulus orientation was relevant for the decision. We decoded the likelihood function from the trial-to-trial population activity and found that it predicted decisions better than a point estimate of orientation. This remained true when we conditioned on the true orientation, suggesting that internal fluctuations in neural activity drive behaviorally meaningful variations in the likelihood function. Our results establish the role of population-encoded likelihood functions in mediating behavior and provide a neural underpinning for Bayesian models of perception.
Journal Article
Perception : a very short introduction
\"Perception is one of the oldest and most deeply investigated topics in the field of psychology, and it also raises some profound philosophical questions. It is concerned with how we use the information reaching our senses to guide and control our behavior as well as to create our particular, subjective experiences of the surrounding world. In this Very Short Introduction, Brian J. Rogers discusses the philosophical question of what it means to perceive, as well as describing how we are able to perceive the particular characteristics of objects and scenes such as their lightness, color, form, depth, and motion. What we perceive, however, does not always correspond to what exists in the world and, as Rogers shows, the study of illusions can be useful in telling us something about the nature and limitations of our perceptual processes. Rogers also explores perception from an evolutionary perspective, explaining how evolutionary pressures have shaped the perceptual systems of humans and other animals. He shows that perception is not necessarily a separate and independent process but rather part of a \"perceptual system,\" involving both the extraction of perceptual information and the control of action. Rogers goes on to cover the significant progress made recently in the understanding of perception through the use of precise and controlled psychophysical methods, single cell recordings, and imaging techniques. There have also been many insights from attempts to model perceptual processes in artificial systems. As Rogers shows, these attempts have revealed how difficult it is to program machines to perform even the most simple of perceptual tasks that we take for granted\"--Publisher's website.
Book
The human imagination: the cognitive neuroscience of visual mental imagery
Mental imagery can be advantageous, unnecessary and even clinically disruptive. With methodological constraints now overcome, research has shown that visual imagery involves a network of brain areas from the frontal cortex to sensory areas, overlapping with the default mode network, and can function much like a weak version of afferent perception. Imagery vividness and strength range from completely absent (aphantasia) to photo-like (hyperphantasia). Both the anatomy and function of the primary visual cortex are related to visual imagery. The use of imagery as a tool has been linked to many compound cognitive processes and imagery plays both symptomatic and mechanistic roles in neurological and mental disorders and treatments.
Journal Article
Eye movements and psychological functions : international views
Originally published in 1983, this volume represents the edited proceedings of the first conference organized by the European Group for Eye Movement Research with the theme \"Eye Movements: Current Research and Methodology\". The conference was held at the Department of Psychology, University of Bern, Switzerland in 1981. The book is divided into four parts covering: Methods; Central and Peripheral Processing; Picture Viewing and Visual Tracking; and Cognitive Processes and Reading. Each part is introduced by one of the session chairpersons of the conference.
BOOK
Illusory ownership of a virtual child body causes overestimation of object sizes and implicit attitude changes
An illusory sensation of ownership over a surrogate limb or whole body can be induced through specific forms of multisensory stimulation, such as synchronous visuotactile tapping on the hidden real and visible rubber hand in the rubber hand illusion. Such methods have been used to induce ownership over a manikin and a virtual body that substitute the real body, as seen from first-person perspective, through a head-mounted display. However, the perceptual and behavioral consequences of such transformed body ownership have hardly been explored. In Exp. 1, immersive virtual reality was used to embody 30 adults as a 4-y-old child (condition C), and as an adult body scaled to the same height as the child (condition A), experienced from the first-person perspective, and with virtual and real body movements synchronized. The result was a strong body-ownership illusion equally for C and A. Moreover there was an overestimation of the sizes of objects compared with a nonembodied baseline, which was significantly greater for C compared with A. An implicit association test showed that C resulted in significantly faster reaction times for the classification of self with child-like compared with adult-like attributes. Exp. 2 with an additional 16 participants extinguished the ownership illusion by using visuomotor asynchrony, with all else equal. The size-estimation and implicit association test differences between C and A were also extinguished. We conclude that there are perceptual and probably behavioral correlates of body-ownership illusions that occur as a function of the type of body in which embodiment occurs.
Journal Article