Whole-brain analysis. The results of the analysis group of the whole brain, superimposed on the group average anatomical scan. (Left) homes OSC ventral and dorsal, activated by the contrast between objects and scrambled univariate intact in alignment with the OSC. (Center) and medial occipital cortex cluster analysis to test the projectors multivoxel spheres that discriminated between the two types of scene (cars vs. people) to the category of independent locator reasons. (Right) The right occipital cluster analysis test multivoxel projectors for spheres of a positive correlation between the category-specific effect of reference and behavioral performance. (C) PNAS, doi: 10.1073/pnas.1101042108 Peelen adds, the memory is obviously a broad term, and most forms of knowledge and recognition can be stated as a way of memory. For example, in our study, participants must have had knowledge of a person or a car might look cluttered scenes to prepare actively for detection. If objects such as shape memory is impaired, it is likely that there will not be able to prepare effectively for the detection of objects, and in extreme cases may not even recognize the objects as a person or a machine.In addition to sensory input and the internal activity of the neocortex, the role of emotions and memory, and their corresponding brain areas, are intimately involved in perception, attention and motivation, and then pre-mediation. It ‘likely that the subcortical structures involved in motivation and arousal play an important role in the temporal aspect of the preparation, Peelen reflects. And ‘to successfully implement our task, participants had to be ready when the scene appeared. However, that preparation time should not be specific to particular categories of objects, but also work in all cases.
In terms of future research, Peelen is preparing a study that uses fMRI in real time to allow participants to see and, hopefully, to control their brain activity during the preparation of visual search. When preparing to search for particular objects, subjects will be asked to increase the business areas or low-level vision (which has hampered the visual search) or high-level visual areas (which have facilitated visual search). Participants become aware of the control region of the brain where a certain day, he says, we hope to discover that we are able to manipulate the participants use the strategy, and to improve performance in participants with a strategy is not optimal due to low-level visual areas .
Peelen note that the unexpected and interesting result is that the activity in the medial prefrontal cortex (mPFC) appears to reflect a source of high-level categories used in the mediation of visual preparatory research. “One interesting area of research monitoring is to determine precisely how the mPFC communicates with other visual cortical areas.”
Given the brain’s ability to perceive the world s using different senses, and the fact that the research was based on symbolic markers (visual and non-specific) has cited the work of CSOs, Peelen said it is expected that the results would be similar with different types of symbolic clues, whether spoken or textual. Indeed, if we want something in our everyday environment, the trigger for research can come from several sources, that is a thought, but also external demand and it is unlikely that the brain has developed mechanisms for each of these indices. A very interesting question is how the brain converts a symbolic reference, as a word, a thought, or a spoken text, a model of visual search that efficiently guide visual search. Very little is known about this process of transformation.
Other ways to improve the fMRI scans could be optogenetics, which allows the passage of individual neurons controlled by short pulses of light, and electrical microstimulation, which uses an array of microelectrodes for interfacing with small groups of neurons with a precision space-time up. Optogenetics has a potential similar to that of electrical microstimulation, Peelen notes, even if s thought to be more precise aims in specific neurons. It could be a useful tool for monitoring the study. For example, our results have shown that the preparedness activities in specific regions of the brain is essential for the identification of objects. Optogenetics electrical microstimulation and perhaps could be used to control the activity of neurons that code for the class of the target object.
Experimental design and analytical approach. (A) Participants were asked to detect either the people or vehicles in briefly presented natural scenes preceded by a warning symbol (a letter or number) indicates the destination category. 33% in the queue, but no scene has been made to isolate the responses to the cue-cue cheating). (B) of the OSC was in each participant by comparing activity in intact scrambled objects, presented in a separate experiment. Voxels activated by this contrast were selected for the analysis of models multivoxel. (C) response patterns to signal only evidence Multivoxel (people and indices of self) in the main study, were correlated with response patterns evoked by images such as people or cars, presented without the context of visual experience of others in a separate category locator . Correlations between-category (against diagonal) were subtracted from the intra-class correlations (horizontal comparisons) to estimate the class specificity of the cue-related activities. (C) PNAS, doi: 10.1073/pnas.1101042108
Led by Asst. Prof. Marius V. Peelen at the Center for Mind / Brain Sciences at the University of Trento in Italy with Professor Sabine Kastner, Department of Psychology and Neuroscience Institute at Princeton University in Princeton, research shows that even when the precise visual features of an object is not known in advance, the higher cortical structures mediating visual search.
(Medical Xpress) – The real world is, in short, crowded, but through evolution, we (and other mammals) have no problem detecting objects in visually complex natural environments. Determine precisely how this happens is misleading because the complex neural mechanisms of the retina responsible for perceptions simple lines, borders, and others do not consider this survival technique, in fact, actually interfere with it. Recently, however, scientists have used magnetic resonance imaging (fMRI) to clarify the process that top-down high-level cortical areas are not concerned with mere perception, but rather abstract perceptual categories, in fact, preparing low-level centers perceive detail in the visual brain disorder.
Venturing further, Peelen said one potential application might lie in computer vision, such as photos or video automatic labeling of search engines or robots. Our paradigm may be very suitable to study the characteristics of essential purpose humans use to perform a visual search, because it can reveal the characteristics of the object that are activated during the preparation of research in the absence of visual stimulation, he notes. It may then be able to design algorithms that implement these functions in computer vision. Considering the automatic retrieval of visual information, in particular the key issue to determine the different ways that the analysis should be used for the detection of different semantic categories in photos and video, researchers have recently made use of the observation that the brain human beings are very good in performing these tasks is accurate and fast.
Thus, he concludes, we may begin to look at the human brain for inspiration on how automatic categorization of view it should work. Science of the brain that connects with the information and communication technology, using modern brain imaging to better design solutions based approach to video search cortex is a promising research direction.
FMRI subjects will be analyzed using fast algorithms to decode the neural signatures of object categories, and how it was done in the current search to find a balance between business models and categories, but in real time. Peelen note that this approach may allow subjects to be presented with feedback on how their brain activity is similar to the model considered to be visual. For example, he notes, auditory stimulation can vary in pitch from how their brain activity is the category index. They can then use their brain activity to optimize the performance of visual search. Important, he adds, because while the performance of a given subject s is relatively fixed, there are significant differences between subjects.
While the technology was already established, and therefore presents significant challenges, Peelen known it takes six seconds to measure a neural signature so it was necessary to address how neural measures had already been confused with the visual activity. We arrived with a clever design in which we showed the visual signal, but then the display of a scene, he added. Since we collected primary data using this technique, the measured signal reflects brain activity in the absence of visual stimulation.
In addition, he continues, a general hypothesis that emerges from our results is that the preparation for the detection of target objects is more effective in certain areas of the brain that can discriminate target objects from the objects of distraction. In our study, we investigated the identification of categories of emotionally neutral objects. We have shown that the OSC was the best discriminator of these categories, and thus the activity of preparation was also more effective in the OSC. However, one could imagine situations in which we actively seek emotional, for example, dangerous objects. In this case, is consistent with our hypothesis that the preparatory activities in the amygdala, where emotional or dangerous objects are thought to be discriminated from non-emotional objects easier to detect. An alternative theory, in fact, an ongoing debate is that structures like the amygdala function independently of the top-down control and allows the detection of emotional stimuli, even if not actively looking for them.
For more information: a neural basis for visual search in real-world human occipital cortex, published online before print, doi: 10.1073/pnas.1101042108, PNAS published July 5, 2011
In addition, he noted that our finding that different people use different search strategies, as evidenced by the activation of different brain areas, may have implications for all situations in which visual search / object detection is important, we included the airport security, military applications, and other areas.
The research activity was measured in a brain region called the object-selective cortex (OSC), while the participants are prepared to find a wide range of representative images of cars and people inside, appears briefly (100 ms) nature scenes who had not already seen. The subjects were given visual cues that specifies the categories of objects (eg cars or people) to be located in the wings. The main conclusion is that the tail alone, even if no stage was demonstrated by the following responses generated OSC determined by analysis of models multivoxel (MVPA) that were very similar to those that occurred when looking at real examples of the index category . Moreover, considering the scenes, this model provides reliable neuronal activity in the subjects ‘performance’ in the cued visual target identification. (In contrast to fMRI analysis, which focuses on individual brain voxels (volumetric pixels), improves the interpretation of MVPA fMRI identifying information in the broader patterns of brain activity.)
In terms of applications, the initial run Peelen’s thoughts for new research, such as working with patients congenitally blind. Even if these people have no visual experience, the organization of their visual system s is similar to that of sighted people, but some key areas to respond to verbal or tactile material. (Braille, for example, activates the same areas of the visual cortex, not only in an individual reading lights.) This indicates that the neural activity that we see in our research may already be conceptual rather than visual in nature, Peelen speculates.
Critical is that this particular activity could be timed precisely, and could be applied before a visual scene displayed. This would allow us to answer some interesting questions, including the specific time interval in which the preparatory work is useful, the specificity of this activity of specific neuronal populations, such as those coding for the target category, and perhaps It is interesting to note that most activities both externally induced preparatory to bring relief to all, or whether it should be guided by, and on, with, from top to bottom as mPFC areas. Indeed, perhaps one might think at once to the stimulation of these regions of origin, and whether the activities and results of the preparatory work in the visual cortex.
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