scholarly journals Anatomical Study of Intrahemispheric Association Fibers in the Brains of Capuchin Monkeys (Sapajussp.)

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Kellen Christina Malheiros Borges ◽  
Hisao Nishijo ◽  
Tales Alexandre Aversi-Ferreira ◽  
Jussara Rocha Ferreira ◽  
Leonardo Ferreira Caixeta
Keyword(s):  
Nonhuman Primates ◽  
Evolutionary Process ◽  
Anatomical Study ◽  
Lateral View ◽  
Superior Longitudinal Fasciculus ◽  
Cognitive Behaviors ◽  
Behavioral Studies ◽  
Inferior Longitudinal Fasciculus ◽  
Association Fibers ◽  
The Brain

Previous studies suggest that the complexity of fiber connections in the brain plays a key role in the evolutionary process of the primate brain and behaviors. The patterns of brain fiber systems have been studied in detail in many nonhuman primates, but not inSapajussp. Behavioral studies indicated thatSapajussp. (bearded capuchins) show highly cognitive behaviors such as tool use comparable to those in other nonhuman primates. To compare the brain fiber systems in capuchins with those in other nonhuman primates and humans, the intrahemispheric fibers systems in 24 cerebral hemispheres ofSapajuswere dissected by a freezing-thawing procedure. Dissection of the hemispheres in lateral view indicated short arcuate fibers, uncinate fasciculus, and inferior longitudinal fasciculus, while that in a medial view indicated short arcuate fibers, the cingulum united with the superior longitudinal fasciculus, and inferior longitudinal fasciculus. The results showed that the fiber systems inSapajusare comparable to those in rhesus and humans, except for a lack of independent superior longitudinal fasciculus and cingulum inSapajus.

MicroPET/CT assessment of neurochemical effects in the brain after long-term methylphenidate treatment in nonhuman primates

2021 ◽  
pp. 107017
Author(s):  
X. Zhang ◽  
J. Talpos ◽  
M.S. Berridge ◽  
S.M. Apana ◽  
W. Slikker ◽  
...  
Keyword(s):  
Nonhuman Primates ◽  
The Brain

scholarly journals Artificial intelligence, dynamic efficiency and Economics

2021 ◽  
pp. 337-350
Author(s):  
Vincent Wolters
Keyword(s):  
Artificial Intelligence ◽  
Optimization Problems ◽  
Evolutionary Process ◽  
Human Action ◽  
Medical Doctor ◽  
Dynamic Efficiency ◽  
Demand And Supply ◽  
New Information ◽  
Back Ground ◽  
The Brain

In this work I will lend support to the theory of «dynamic efficien - cy», as outlined by Prof. Huerta de Soto in The Theory of Dynamic Efficiency (2010a). Whereas Huerta de Soto connects economics with ethics, I will take a different approach. Since I have a back-ground in Artificial Intelligence (A.I.), I will show that this and related fields have yielded insights that, when applied to the study of economics, may call for a different way of looking at the eco-nomy and its processes. At first glance, A.I. and economics do not seem to have a lot in common. The former is thought to attempt to build a human being; the latter is supposed to deal with depressions, growth, inflation, etc. That view is too simplistic; in fact there are strong similarities. First, economics is based on (inter-)acting individuals, i.e. on human action. A.I. tries to understand and simulate human (and animal) behavior. Second, economics deals with information pro-cessing, such as how the allocation of resources can best be orga-nized. A.I. also investigates information processing. This can be in specific systems, such as the brain, or the evolutionary process, or purely in an abstract form. Finally, A.I. tries to answer more philosophical questions like: what is intelligence? What is a mind? What is consciousness? Is there free will? These topics play a less prominent role in economics, but are sometimes touched upon, together with the related topic of the «entrepreneurial function». The paradigm that was dominant in the early days of A.I. is static in nature. Reaching a solution is done in different steps. First: gathering all necessary information. Second: processing this in - formation. Finally: the outcome of this process, a clear conclusion. Each step in the process is entirely separate. During information gathering no processing is done, and during processing, no new information is added. The conclusion reached is final and cannot change later on. Logical problems are what is mostly dealt with, finding ways in which a computer can perform deductions based on the information that is represented as logical statements. Other applications are optimization problems, and so-called «Expert Systems», developed to perform the work of a judge reaching a verdict, or a medical doctor making a diagnosis based on the symptoms of the patient. This paradigm is also called «top-down», because information flows to a central point where it is processed, or «symbolic processing», referring to deduction in formal logic.1 In economics there is a similar paradigm, and it is still the do-minant one. This is the part of economics that deals with opti - mization of resources: given costs and given prices, what is the allocation that will lead to the highest profit? Also belonging to this paradigm are the equilibrium models. Demand and supply curves are supposed to be knowable and unchangeable, and the price is a necessary outcome. The culmination is central planning that supposes all necessary information, such as demand and supply curves and available resources to be known. Based on this, the central planner determines prices.

scholarly journals Orexin receptor blockers: A tool for lowering alcohol intake and alcohol addictive behavior in the light of preclinical studies

2021 ◽  
Vol 75 (1) ◽  
pp. 959-969
Author(s):  
Kamila Czora-Poczwardowska ◽  
Radosław Kujawski ◽  
Julia Słyńko-Krzyżostaniak ◽  
Przemysław Ł. Mikołajczak ◽  
Michał Szulc
Keyword(s):  
Alcohol Intake ◽  
Selective Reduction ◽  
Optimization Methods ◽  
Sugar Solution ◽  
Behavioral Studies ◽  
Potential Efficacy ◽  
Bioactive Ligands ◽  
Receptor Blockers ◽  
Rats And Mice ◽  
The Brain

Abstract Alcohol use disorder (AUD) is a severe and globally widespread neurological and psychiatric problem. The treatment with currently used drugs often does not bring the expected effect. New optimization methods or directions in pharmacotherapy are still being sought. The group of bioactive ligands, targeted at neuropeptides called orexins (OXs) and their receptors (OXRs), affects a number of functions including ingestion, sleep-wake regulation, as well as the brain reward system which is the basis of addiction. The purpose of this paper is to systematize the knowledge in the field of preclinical behavioral studies on rodents (rats and mice) in several models of alcohol consumption using the OXRs antagonists. The results of the experiments indicated a potential efficacy of particular OXRs antagonists in the AUD treatment, especially those selectively blocking the OX1R. Among them, SB-334867 in the lowest effective dose of 3 mg/kg i.p. was most studied, as shown in the model of two-bottle choice using C57BL/6 mice. Moreover, this compound did not affect the reduction of cognitive functions. GSK1059865 was also involved in the selective reduction of ethanol intake, and simultaneously did not alter the consumption of sugar solution. The other group of selective OX2R antagonists, such as TCS-OX2-29 and LSN2424100, was less efficient. In summary, the OX1R antagonists proved to have the potential in AUD therapy, not only through the reduction of ethanol consumption but also in the treatment of coexisting behavioral and physiological disorders, such as insomnia and anxiety.

scholarly journals Learning what is irrelevant or relevant: Expectations facilitate distractor inhibition and target facilitation through distinct neural mechanisms

2019 ◽  
Author(s):  
Dirk van Moorselaar ◽  
Heleen A. Slagter
Keyword(s):  
Target Location ◽  
Response Times ◽  
Relevant Information ◽  
Distractor Location ◽  
Distractor Inhibition ◽  
Distractor Processing ◽  
Behavioral Studies ◽  
Outstanding Question ◽  
Target Locations ◽  
The Brain

AbstractIt is well known that attention can facilitate performance by top-down biasing processing of task-relevant information in advance. Recent findings from behavioral studies suggest that distractor inhibition is not under similar direct control, but strongly dependent on expectations derived from previous experience. Yet, how expectations about distracting information influence distractor inhibition at the neural level remains unclear. The current study addressed this outstanding question in three experiments in which search displays with repeating distractor or target locations across trials allowed observers to learn which location to selectively suppress or boost. Behavioral findings demonstrated that both distractor and target location learning resulted in more efficient search, as indexed by faster response times. Crucially, benefits of distractor learning were observed without target location foreknowledge, unaffected by the number of possible target locations, and could not be explained by priming alone. To determine how distractor location expectations facilitated performance, we applied a spatial encoding model to EEG data to reconstruct activity in neural populations tuned to the distractor or target location. Target location learning increased neural tuning to the target location in advance, indicative of preparatory biasing. This sensitivity increased after target presentation. By contrast, distractor expectations did not change preparatory spatial tuning. Instead, distractor expectations reduced distractor-specific processing, as reflected in the disappearance of the Pd ERP component, a neural marker of distractor inhibition, and decreased decoding accuracy. These findings suggest that the brain may no longer process expected distractors as distractors, once it has learned they can safely be ignored.Significance statementWe constantly try hard to ignore conspicuous events that distract us from our current goals. Surprisingly, and in contrast to dominant attention theories, ignoring distracting, but irrelevant events does not seem to be as flexible as is focusing our attention on those same aspects. Instead, distractor suppression appears to strongly rely on learned, context-dependent expectations. Here, we investigated how learning about upcoming distractors changes distractor processing and directly contrasted the underlying neural dynamics to target learning. We show that while target learning enhanced anticipatory sensory tuning, distractor learning only modulated reactive suppressive processing. These results suggest that expected distractors may no longer be considered distractors by the brain once it has learned that they can safely be ignored.

Behavioral and Neurophysiological Demonstration of a Lateralis Skin Photosensitivity in Larval Sea Lampreys

1991 ◽  
Vol 161 (1) ◽  
pp. 97-117 ◽  
Author(s):  
MARK RONAN ◽  
DAVID BODZNICK
Keyword(s):  
Spontaneous Activity ◽  
Lateral Line ◽  
Lateral Line Nerve ◽  
Medial Nucleus ◽  
Posterior Lateral Line ◽  
Behavioral Studies ◽  
Sea Lampreys ◽  
Response Thresholds ◽  
The Brain ◽  
Skin Photosensitivity

Larval lampreys respond to skin illumination with a delayed burst of swimming in an attempt to escape the light. The photoresponse, which is independent of the lateral eyes and pineal organs, is most readily elicited by light shone on the tail. Behavioral studies in larval lampreys demonstrate that photosensory afferents innervating the tail are carried by a trunk lateral line nerve supplying regions caudal to the head. The present results confirm that bilateral transection of this nerve in larval sea lampreys markedly diminishes the photoresponse. The trunk lateral line nerve consists of the recurrent ramus of the anterior lateral line nerve and a ramus of the posterior lateral line nerve. Bilateral transection of the recurrent ramus does not affect the photoresponse, indicating that lateralis photosensory afferents enter the brain via the posterior lateral line nerve and terminate in the medial octavolateralis nucleus. Photosensory units were subsequently recorded in the trunk lateral line nerve, posterior lateral line nerve and the lateral line area of the medulla. Medullary photosensory units were localized to the medial nucleus, previously regarded as the primary mechanosensory nucleus. Photosensory units in lateral line nerves and the brain exhibited low, irregular spontaneous activity and, after latencies of 17–4 s, responded to tail illumination with repeated impulse bursts. Response thresholds were 0.1-0.9 mWcm−2. Responses to sustained illumination were slowly adapting. A skin photosense is thus an additional lateralis modality in lampreys.

scholarly journals Alteration of the Intra- and Inter-Lobe Connectivity of the Brain Structural Network in Normal Aging

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 826
Author(s):  
Chi-Wen Jao ◽  
Jiann-Horng Yeh ◽  
Yu-Te Wu ◽  
Li-Ming Lien ◽  
Yuh-Feng Tsai ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Right Hemisphere ◽  
Morphological Changes ◽  
The Elderly ◽  
Elderly Group ◽  
Component Size ◽  
Parietal Lobes ◽  
Structural Network ◽  
Association Fibers ◽  
The Brain

The morphological changes in cortical parcellated regions during aging and whether these atrophies may cause brain structural network intra- and inter-lobe connectivity alterations are subjects that have been minimally explored. In this study, a novel fractal dimension-based structural network was proposed to measure atrophy of 68 parcellated cortical regions. Alterations of structural network parameters, including intra- and inter-lobe connectivity, were detected in a middle-aged group (30–45 years old) and an elderly group (50–65 years old). The elderly group exhibited significant lateralized atrophy in the left hemisphere, and most of these fractal dimension atrophied regions were included in the regions of the “last-in, first-out” model. Globally, the elderly group had lower modularity values, smaller component size modules, and fewer bilateral association fibers. They had lower intra-lobe connectivity in the frontal and parietal lobes, but higher intra-lobe connectivity in the temporal and occipital lobes. Both groups exhibited similar inter-lobe connecting pattern. The elderly group revealed separations, sparser long association fibers, commissural fibers, and lateral inter-lobe connectivity lost effect, mainly in the right hemisphere. New wiring and reconfiguring modules may have occurred within the brain structural network to compensate for connectivity, decreasing and preventing functional loss in cerebral intra- and inter-lobe connectivity.

scholarly journals Time course of spatiotopic updating across saccades

2019 ◽  
Vol 116 (6) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jasper H. Fabius ◽  
Alessio Fracasso ◽  
Tanja C. W. Nijboer ◽  
Stefan Van der Stigchel
Keyword(s):  
Eye Movements ◽  
Visual System ◽  
Eye Movement ◽  
Time Course ◽  
Saccadic Eye Movements ◽  
Oculomotor System ◽  
Stimulus Onset ◽  
Oculomotor Behavior ◽  
Behavioral Studies ◽  
The Brain

Humans move their eyes several times per second, yet we perceive the outside world as continuous despite the sudden disruptions created by each eye movement. To date, the mechanism that the brain employs to achieve visual continuity across eye movements remains unclear. While it has been proposed that the oculomotor system quickly updates and informs the visual system about the upcoming eye movement, behavioral studies investigating the time course of this updating suggest the involvement of a slow mechanism, estimated to take more than 500 ms to operate effectively. This is a surprisingly slow estimate, because both the visual system and the oculomotor system process information faster. If spatiotopic updating is indeed this slow, it cannot contribute to perceptual continuity, because it is outside the temporal regime of typical oculomotor behavior. Here, we argue that the behavioral paradigms that have been used previously are suboptimal to measure the speed of spatiotopic updating. In this study, we used a fast gaze-contingent paradigm, using high phi as a continuous stimulus across eye movements. We observed fast spatiotopic updating within 150 ms after stimulus onset. The results suggest the involvement of a fast updating mechanism that predictively influences visual perception after an eye movement. The temporal characteristics of this mechanism are compatible with the rate at which saccadic eye movements are typically observed in natural viewing.

Chapter XII: Summary and Conclusion

1980 ◽  
Vol 25 (S1) ◽  
pp. 145-152
Author(s):  
Richard Albert Wilson
Keyword(s):  
Spiral Structure ◽  
Evolutionary Process ◽  
The World ◽  
In Virtue Of ◽  
The Brain

The termination of the world in a man appears to be the last victory of the intelligence. … An individual man is a fruit which it cost all the foregoing ages to form and ripen. … Each individual soul is such, in virtue of its being a power to translate the world into some particular language of its own.—EMERSON, The Method of Nature, 1841.Our story of evolution ended with a stirring in the brain-organ of the latest of nature’s experiments; but that stirring of consciousness transmutes the whole story and gives meaning to its symbolism.—EDDINGTON, Science and the Unseen World, 1929.It may be worth while now to summarize in a page or two the view of world evolution as outlined above, a spiral structure of which man’s created language forms the final story. In this summary I adopt the organic hypothesis, which assumes that mind is a basic and permanent element in the world, self-determining and purposive in its nature, and the directing agency in the evolutionary process throughout its history. While the acceptance or rejection of this metaphysical hypothesis is not essential to the acceptance or rejection of the scientific exposition of the birth and structure of language given in the preceding pages, the choice of one or other hypothesis does, of course, make a rather complete difference in the diction and phraseology chosen to set out the specific exposition. To a mechanist many of the terms which I have used may appear altogether unwarranted or quite wrong.

Opposed optimal strategies of weighting somatosensory inputs for planning reaching movements toward visual and proprioceptive targets

2014 ◽  
Vol 112 (9) ◽  
pp. 2290-2301 ◽  
Author(s):  
Jean Blouin ◽  
Anahid H. Saradjian ◽  
Nicolas Lebar ◽  
Alain Guillaume ◽  
Laurence Mouchnino
Keyword(s):  
Visual Feedback ◽  
Sensory Modality ◽  
Optimal Strategies ◽  
Neural Correlates ◽  
Movement Planning ◽  
Reaching Movements ◽  
Behavioral Studies ◽  
Somatosensory Input ◽  
Visual Targets ◽  
The Brain

Behavioral studies have suggested that the brain uses a visual estimate of the hand to plan reaching movements toward visual targets and somatosensory inputs in the case of somatosensory targets. However, neural correlates for distinct coding of the hand according to the sensory modality of the target have not yet been identified. Here we tested the twofold hypothesis that the somatosensory input from the reaching hand is facilitated and inhibited, respectively, when planning movements toward somatosensory (unseen fingers) or visual targets. The weight of the somatosensory inputs was assessed by measuring the amplitude of the somatosensory evoked potential (SEP) resulting from vibration of the reaching finger during movement planning. The target sensory modality had no significant effect on SEP amplitude. However, Spearman's analyses showed significant correlations between the SEPs and reaching errors. When planning movements toward proprioceptive targets without visual feedback of the reaching hand, participants showing the greater SEPs were those who produced the smaller directional errors. Inversely, participants showing the smaller SEPs when planning movements toward visual targets with visual feedback of the reaching hand were those who produced the smaller directional errors. No significant correlation was found between the SEPs and radial or amplitude errors. Our results indicate that the sensory strategy for planning movements is highly flexible among individuals and also for a given sensory context. Most importantly, they provide neural bases for the suggestion that optimization of movement planning requires the target and the reaching hand to both be represented in the same sensory modality.

scholarly journals Anatomical basis of approaches to foramen magnum and lower clival meningiomas: comparison of retrosigmoid and transcondylar approaches

2003 ◽  
Vol 14 (6) ◽  
pp. 1-5 ◽  
Author(s):  
Agustinus Suhardja ◽  
Anne M. R. Agur ◽  
Michael D. Cusimano
Keyword(s):  
Anatomical Study ◽  
Foramen Magnum ◽  
The Other ◽  
Retrosigmoid Approach ◽  
Surface Areas ◽  
Anatomical Basis ◽  
Paired Student ◽  
The Mean ◽  
Lower Clivus ◽  
The Brain

Object Meningiomas of the lower clivus and foramen magnum are among the most challenging of all neurosurgical lesions. Debate continues regarding the most appropriate approach to this eloquent anatomical region. This anatomical study was undertaken to measure and compare the area of surgical exposures of the lower clivus achieved using the retrosigmoid and the extreme-lateral transcondylar (ELT) approaches. Methods Thirteen embalmed cadaveric heads were dissected bilaterally via the retrosigmoid approach on one side and the ELT approach on the other. The circumference of the area of exposure was delineated using beaded pins placed into the dura. After removal of the brain, the longest longitudinal and transverse axes of the pinned areas were measured and surface area calculated. The area of surgical exposure was also expressed as a percentage of the total area of the lower clivus. Normalized and adjusted surface areas were calculated using the bimastoid diameter. The areas of exposure were compared using the two-tailed paired Student t-test. The mean area of exposure required using the retrosigmoid approach was 19.8 ±14.7 mm2 (range 6–49 mm2) and that using the ELT approach was 27.8 ±22.8 mm2 (range 10–90 mm2). The mean percentage of the lower clivus exposed by the retrosigmoid approach was 14.9 ±3.6% (range 10–22%) and that exposed by the ELT approach was 20.5 ± 4.9% (range 10–25%). The ELT approach provided significantly greater area of operative exposure and allowed a significantly higher percentage of lower clivus and foramen magnum exposure than did the retrosigmoid approach (p <0.05). Normalized and adjusted surface areas, taking into consideration the bimastoid diameter, were also statistically significant in favor of the ELT approach. Conclusions The ELT approach provided a significantly greater area of exposure than did the retrosigmoid approach.

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