Encoding of graded changes in spatial specificity of prior cues in human visual cortex

2014 ◽  
Vol 112 (11) ◽  
pp. 2834-2849 ◽  
Author(s):  
Yuko Hara ◽  
Justin L. Gardner
Keyword(s):  
Prior Information ◽  
Prior Probability ◽  
Blood Oxygenation ◽  
Response Magnitude ◽  
Behavioral Performance ◽  
Significant Difference ◽  
Cortical Responses ◽  
Sensory Responses ◽  
Contrast Discrimination ◽  
Spatial Specificity

Prior information about the relevance of spatial locations can vary in specificity; a single location, a subset of locations, or all locations may be of potential importance. Using a contrast-discrimination task with four possible targets, we asked whether performance benefits are graded with the spatial specificity of a prior cue and whether we could quantitatively account for behavioral performance with cortical activity changes measured by blood oxygenation level-dependent (BOLD) imaging. Thus we changed the prior probability that each location contained the target from 100 to 50 to 25% by cueing in advance 1, 2, or 4 of the possible locations. We found that behavioral performance (discrimination thresholds) improved in a graded fashion with spatial specificity. However, concurrently measured cortical responses from retinotopically defined visual areas were not strictly graded; response magnitude decreased when all 4 locations were cued (25% prior probability) relative to the 100 and 50% prior probability conditions, but no significant difference in response magnitude was found between the 100 and 50% prior probability conditions for either cued or uncued locations. Also, although cueing locations increased responses relative to noncueing, this cue sensitivity was not graded with prior probability. Furthermore, contrast sensitivity of cortical responses, which could improve contrast discrimination performance, was not graded. Instead, an efficient-selection model showed that even if sensory responses do not strictly scale with prior probability, selection of sensory responses by weighting larger responses more can result in graded behavioral performance benefits with increasing spatial specificity of prior information.

scholarly journals Impaired Learning and Memory Ability Induced by a Bilaterally Hippocampal Injection of Streptozotocin in Mice: Involved With the Adaptive Changes of Synaptic Plasticity

2021 ◽  
Vol 13 ◽  
Author(s):  
Cong-Cong Qi ◽  
Xing-Xing Chen ◽  
Xin-Ran Gao ◽  
Jing-Xian Xu ◽  
Sen Liu ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Protein Expression ◽  
Learning And Memory ◽  
Psychiatric Symptoms ◽  
Wnt Signaling Pathway ◽  
Behavioral Performance ◽  
Adaptive Changes ◽  
Memory Ability ◽  
Significant Difference ◽  
Gsk 3Β

Background: Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive cognitive decline, psychiatric symptoms and behavioral disorders, resulting in disability, and loss of self-sufficiency.Objective: To establish an AD-like mice model, investigate the behavioral performance, and explore the potential mechanism.Methods: Streptozotocin (STZ, 3 mg/kg) was microinjected bilaterally into the dorsal hippocampus of C57BL/6 mice, and the behavioral performance was observed. The serum concentrations of insulin and nesfatin-1 were measured by ELISA, and the activation of hippocampal microglia and astrocytes was assessed by immunohistochemistry. The protein expression of several molecular associated with the regulation of synaptic plasticity in the hippocampus and the pre-frontal cortex (PFC) was detected via western blotting.Results: The STZ-microinjected model mice showed a slower bodyweight gain and higher serum concentration of insulin and nesfatin-1. Although there was no significant difference between groups with regard to the ability of balance and motor coordination, the model mice presented a decline of spontaneous movement and exploratory behavior, together with an impairment of learning and memory ability. Increased activated microglia was aggregated in the hippocampal dentate gyrus of model mice, together with an increase abundance of Aβ1−42 and Tau in the hippocampus and PFC. Moreover, the protein expression of NMDAR2A, NMDAR2B, SynGAP, PSD95, BDNF, and p-β-catenin/β-catenin were remarkably decreased in the hippocampus and the PFC of model mice, and the expression of p-GSK-3β (ser9)/GSK-3β were reduced in the hippocampus.Conclusion: A bilateral hippocampal microinjection of STZ could induce not only AD-like behavioral performance in mice, but also adaptive changes of synaptic plasticity against neuroinflammatory and endocrinal injuries. The underlying mechanisms might be associated with the imbalanced expression of the key proteins of Wnt signaling pathway in the hippocampus and the PFC.

scholarly journals The influence of the dynamics and the level of maturity of the cortical functions as a prerequisite for the development of speech in children

2019 ◽  
Vol 147 (3-4) ◽  
pp. 199-204
Author(s):  
Maja Davidovic ◽  
Jadranka Otasevic ◽  
Nada Dobrota-Davidovic ◽  
Ivana Petronic ◽  
Dragomir Davidovic ◽  
...  
Keyword(s):  
Motor Control ◽  
Evoked Potentials ◽  
Physiological Changes ◽  
Articulation Disorder ◽  
Significant Difference ◽  
Cortical Responses ◽  
Quasi Experimental ◽  
Waveform Amplitude ◽  
And Control ◽  
The Impact

Introduction/Objective. The development of speech is the result of interaction of different systems of the cortex, which gradually acquires the ability of phonological presentation and motor control, in the presence of a series of physical and physiological changes in the morphology of the articulation system. The objective of the study was to examine the impact of laterality and cortical responses on the development of speech in children. Methods. Research is a quasi-experimental design with two groups. The sample covered 60 children from Belgrade, of both sexes, ages 5.5?7 years, divided into two groups, experimental (30) and control (30). We used the following instruments: test for assessing laterality and ascertaining evoked potentials. Results. On the visual lateralization subtest there was a statistically significant difference (?2 = 7.56, p < 0.05) between the observed groups. The visual evoked potentials on all measured parameters gave a statistically significant difference between the groups: waveform cortical responses ? left (?2 = 30.00, df = 1, p < 0.05); cortical responses ? right (?2 = 6.667, df = 1 , p < 0.05); waveform amplitude ? left (?2 = 13.469, df = 1, p < 0.05); amplitude ? right (?2 = 40.00, df = 1, p < 0.05), somatosensory potentials (?2 = 18.261, df = 1, p <0.05); waveform amplitude (?2 = 12.000, df = 1, p < 0.05); waveform latency (?2 = 5.455, df = 1, p < 0.05). Conclusion. Visual laterality, as well as visual and somatosensory cortical responses to stimuli is better in children without the present articulation disorder, which could be used for timely prevention planning.

scholarly journals P3 Cognitive Potential in Cochlear Implant Users

2018 ◽  
Vol 22 (04) ◽  
pp. 408-414 ◽  
Author(s):  
Signe Grasel ◽  
Mario Greters ◽  
Maria Goffi-Gomez ◽  
Roseli Bittar ◽  
Raimar Weber ◽  
...  
Keyword(s):  
Speech Recognition ◽  
Cochlear Implant ◽  
Auditory Processing ◽  
Evoked Potential ◽  
Control Group ◽  
Central Auditory Processing ◽  
Speech Discrimination ◽  
Significant Difference ◽  
Cortical Responses ◽  
Peripheral Auditory System

Introduction The P3 cognitive evoked potential is recorded when a subject correctly identifies, evaluates and processes two different auditory stimuli. Objective to evaluate the latency and amplitude of the P3 evoked potential in 26 cochlear implant users with post-lingual deafness with good or poor speech recognition scores as compared with normal hearing subjects matched for age and educational level. Methods In this prospective cohort study, auditory cortical responses were recorded from 26 post-lingual deaf adult cochlear implant users (19 with good and 7 with poor speech recognition scores) and 26 control subjects. Results There was a significant difference in the P3 latency between cochlear implant users with poor speech recognition scores (G-) and their control group (CG) (p = 0.04), and between G- and cochlear implant users with good speech discrimination (G+) (p = 0.01). We found no significant difference in the P3 latency between the CG and G+. In this study, all G- patients had deafness due to meningitis, which suggests that higher auditory function was impaired too. Conclusion Post-lingual deaf adult cochlear implant users in the G- group had prolonged P3 latencies as compared with the CG and the cochlear implant users in the G+ group. The amplitudes were similar between patients and controls. All G- subjects were deaf due to meningitis. These findings suggest that meningitis may have deleterious effects not only on the peripheral auditory system but on the central auditory processing as well.

scholarly journals The effects of post-operative oxygen supply on blood oxygenation and acid-base status in rats anaesthetized with fentanyl/fluanisone and midazolam

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255829
Author(s):  
Leander Gaarde ◽  
Stefanie Kolstrup ◽  
Peter Bollen
Keyword(s):  
Oxygen Saturation ◽  
Oxygen Supply ◽  
Respiratory Acidosis ◽  
Blood Oxygenation ◽  
Acid Base ◽  
Blood Oxygen Saturation ◽  
Arterial Blood ◽  
Post Operative Period ◽  
Significant Difference ◽  
Acid Base Status

In anaesthetic practice the risk of hypoxia and arterial blood gas disturbances is evident, as most anaesthetic regimens depress the respiratory function. Hypoxia may be extended during recovery, and for this reason we wished to investigate if oxygen supply during a one hour post-operative period reduced the development of hypoxia and respiratory acidosis in rats anaesthetized with fentanyl/fluanisone and midazolam. Twelve Sprague Dawley rats underwent surgery and were divided in two groups, breathing either 100% oxygen or atmospheric air during a post-operative period. The peripheral blood oxygen saturation and arterial acid-base status were analyzed for differences between the two groups. We found that oxygen supply after surgery prevented hypoxia but did not result in a significant difference in the blood acid-base status. All rats developed respiratory acidosis, which could not be reversed by supplemental oxygen supply. We concluded that oxygen supply improved oxygen saturation and avoided hypoxia but did not have an influence on the acid-base status.

scholarly journals Effects of Task Difficulty and Target Likelihood in Area V4 of Macaque Monkeys

2006 ◽  
Vol 96 (5) ◽  
pp. 2377-2387 ◽  
Author(s):  
C. Elizabeth Boudreau ◽  
Tori H. Williford ◽  
John H. R. Maunsell
Keyword(s):  
Spatial Attention ◽  
Cortical Neurons ◽  
Task Difficulty ◽  
Focus Of Attention ◽  
Behavioral Performance ◽  
Neuronal Responses ◽  
Fixed Amount ◽  
Processing Resource ◽  
Area V4 ◽  
Sensory Responses

Spatial attention improves performance at attended locations and correspondingly modulates firing rates of cortical neurons. The size of these behavioral and neuronal effects depends on the difficulty of the task performed at the attended location. Psychological theorists have attributed this to a tighter focus of a fixed amount of processing resource at the attended location, but the effects of task difficulty on the distribution of neuronal effects of attention across the visual field have not been fully explored. We trained rhesus monkeys to do a detection task in which difficulty and spatial attention were manipulated independently. Probe stimuli were used to measure behavioral performance in different conditions of attention and difficulty. Animals performed better at attended locations and this advantage increased with difficulty, consistent with data from human psychophysics. Neuronal modulation by spatial attention was larger with greater difficulty. In two animals, increasing difficulty caused a modest increase in neuronal responses to visual stimuli regardless of the locus of spatial attention. In a third animal, which was previously trained to ignore multiple distracting stimuli, increasing task difficulty increased responses at the focus of attention and suppressed responses away from the focus of attention. The results show that difficulty can modulate effects of spatial attention in V4; it can alter the distribution of sensory responses across the visual scene in ways that may depend on the subject's behavioral strategy.

scholarly journals Optical Intrinsic Signal Imaging Responses Are Modulated in Rodent Somatosensory Cortex during Simultaneous Whisker and Forelimb Stimulation

1998 ◽  
Vol 18 (9) ◽  
pp. 968-977 ◽  
Author(s):  
Anne J. Blood ◽  
Arthur W. Toga
Keyword(s):  
Evoked Potentials ◽  
Barrel Cortex ◽  
Response Magnitude ◽  
Response Patterns ◽  
Response Modulation ◽  
Intrinsic Signal ◽  
Optical Intrinsic Signal ◽  
Individual Trial ◽  
Cortical Responses ◽  
Different Response

Optical intrinsic signal imaging(OIS) was used to investigate physiologic interactions between spatially and functionally distinct cortical somatosensory systems. The OIS response magnitude was evaluated after simultaneous stimulation of single whiskers and forelimb digits. Whisker C1 was deflected at a frequency of 10 Hz for 2 seconds while low- or high-intensity vibratory stimuli were applied to forelimb digits. The OIS responses to simultaneous whisker and forelimb stimulation were compared with lone whisker stimulated controls. Overall, addition of a second stimulus caused decreases in barrel cortex response magnitude. Three different response patterns were detected within individual trial sets. Modulation of barrel cortex evoked potentials provided evidence that changes in OIS responses observed here may be partially influenced by vascular responses to changes in neuronal activity. However, OIS responses in the barrel region during lone forelimb stimulation that were unaccompanied by evoked potentials suggested the possibility of independent vascular dynamic influences on response modulation. This study demonstrates that cortical responses at the level of primary sensory processing may be significantly influenced by activity in adjacent regions. Furthermore, it reveals that vascular and neuronal characteristics of interregional modulation do not co-localize and may produce responses in which one component increases while the other decreases.

scholarly journals O Ouro Atua Como Hedge ou Valor Refúgio Diante de Desvalorizações da BM&FBOVESPA?

2017 ◽  
Vol 14 (4) ◽  
pp. 579
Author(s):  
Leonardo Oliveira Penna De Carvalho ◽  
Ademir Luis Teles Brito ◽  
Malu Brandão Moura ◽  
Eliane Silva Conceição ◽  
Eliane Silva Conceição ◽  
...  
Keyword(s):  
Mutual Funds ◽  
Performance Measure ◽  
Behavioral Performance ◽  
Investment Horizon ◽  
Average Performance ◽  
Significant Difference ◽  
The Usa ◽  
The Mean ◽  
Omega Measure

This work has analyzed the performance of 31 behavioral mutual funds in the USA, Europe and Japan described in Santoni and Kelshiker (2010). Were observed the performances of the funds and their respective benchmarks in four indicators: the Sharpe index, Sortino Index, Omega Measure and the Behavioral Performance Measure. The horizon of analysis was 10 years (Jan/04 to Dec/14) divided in intervals of 6, 12, 36, 60 and 120 months. Based on the consolidation of indicators the funds were ranked and classified into three bands of performance: top, middle and bottom. In the interval of 120 months there was, in general, no significant (5%) difference in the average performance between the funds and the benchmarks. The analysis by intervals indicated that the performance of the funds in relation to the benchmarks worsen as the investment horizon increases. In shorter intervals (6 and 12 months) there was, in average, a significant difference in performance while in longer maturities (36 and 60 months) the average performance of the funds was significantly lower than the benchmarks. In the mean of all intervals the average performance of the funds was significantly lower than the benchmarks

scholarly journals Agreement of novel hemodynamic imaging parameters for the acute and chronic stages of ischemic stroke: a matched-pair cohort study

2021 ◽  
Vol 51 (1) ◽  
pp. E12
Author(s):  
Martina Sebök ◽  
Christiaan Hendrik Bas van Niftrik ◽  
Susanne Wegener ◽  
Andreas Luft ◽  
Luca Regli ◽  
...  
Keyword(s):  
Regression Analysis ◽  
Ischemic Stroke ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Blood Oxygenation ◽  
Matched Pair ◽  
Imaging Parameters ◽  
Study Results ◽  
Significant Difference ◽  
Ischemic Events

OBJECTIVE In symptomatic patients with cerebrovascular steno-occlusive disease, impaired blood oxygenation level–dependent cerebrovascular reactivity (BOLD-CVR) and increased flow velocity of the P2 segment of the posterior cerebral artery (PCA-P2) on transcranial Doppler (TCD) ultrasonography have been introduced as emerging clinical imaging parameters to identify patients at high risk for recurrent ischemic events. Since hemodynamic physiology differs between the acute and chronic stages of ischemic stroke, the authors sought to investigate whether those parameters have merit for both the acute and chronic stages of ischemic stroke. METHODS From a prospective database, patients who underwent BOLD-CVR and TCD examinations in the acute stroke stage (< 10 days) were matched to patients in the chronic stroke stage (> 3 months). A linear regression analysis for both groups was performed between ipsilateral PCA-P2 systolic flow velocity and BOLD-CVR of the ipsilateral (affected) hemisphere, the ipsilateral middle cerebral artery (MCA) territory, and the ipsilateral steal volume (i.e., paradoxical BOLD-CVR response). The resulting slopes and intercepts were statistically compared to evaluate differences between groups. RESULTS Forty matched patient pairs were included. Regression analysis showed no significant difference for either the intercept (p = 0.84) or the slope (p = 0.85) between PCA-P2 flow velocity and BOLD-CVR as measured for the ipsilateral (affected) hemisphere. Similarly, no significant difference was seen between PCA-P2 flow velocity and BOLD-CVR of the ipsilateral MCA territory (intercept, p = 0.72; slope, p = 0.36) or between PCA-P2 flow velocity and steal volume (intercept, p = 0.59; slope, p = 0.34). CONCLUSIONS The study results indicated that the relationship between ipsilateral PCA-P2 systolic flow velocity and BOLD-CVR remains the same during the acute and chronic stages of ischemic stroke. This provides further support that these novel hemodynamic imaging parameters may have merit to assess the risk for recurrent ischemic events for a wide ischemic stroke population. PCA-P2 systolic flow velocity, in particular, may be a highly practical screening tool, independent of ischemic stroke stage.

scholarly journals Fundos Comportamentais possuem Desempenho Superior? Uma Análise baseada em Evidências Internacionais

2017 ◽  
Vol 14 (4) ◽  
pp. 479
Author(s):  
Robson Costa Reis ◽  
Marcelo Cabus Klotzle ◽  
Antonio Carlos Figueiredo Pinto ◽  
Leonardo Lima Gomes
Keyword(s):  
Mutual Funds ◽  
Performance Measure ◽  
Behavioral Performance ◽  
Investment Horizon ◽  
Average Performance ◽  
Significant Difference ◽  
The Usa ◽  
The Mean ◽  
Omega Measure

This work has analyzed the performance of 31 behavioral mutual funds in the USA, Europe and Japan described in Santoni and Kelshiker (2010). Were observed the performances of the funds and their respective benchmarks in four indicators: the Sharpe index, Sortino Index, Omega Measure and the Behavioral Performance Measure. The horizon of analysis was 10 years (Jan/04 to Dec/14) divided in intervals of 6, 12, 36, 60 and 120 months. Based on the consolidation of indicators the funds were ranked and classified into three bands of performance: top, middle and bottom. In the interval of 120 months there was, in general, no significant (5%) difference in the average performance between the funds and the benchmarks. The analysis by intervals indicated that the performance of the funds in relation to the benchmarks worsen as the investment horizon increases. In shorter intervals (6 and 12 months) there was, in average, a significant difference in performance while in longer maturities (36 and 60 months) the average performance of the funds was significantly lower than the benchmarks. In the mean of all intervals the average performance of the funds was significantly lower than the benchmarks

scholarly journals Arterial blood contrast (ABC) enabled by magnetization transfer (MT): a novel MRI technique for enhancing the measurement of brain activation changes

2020 ◽  
Author(s):  
Jenni Schulz ◽  
Zahra Fazal ◽  
Riccardo Metere ◽  
José P. Marques ◽  
David G. Norris
Keyword(s):  
Image Quality ◽  
Magnetization Transfer ◽  
Brain Activation ◽  
Functional Brain Imaging ◽  
Blood Oxygenation ◽  
Acquisition Time ◽  
Measured Signal ◽  
Arterial Blood ◽  
Oxygenation Level ◽  
Spatial Specificity

AbstractFunctional brain imaging in humans is almost exclusively performed using blood oxygenation level dependent (BOLD) contrast. This typically requires a period of tens of milliseconds after excitation of the spin system to achieve maximum contrast, leading to inefficient use of acquisition time, reduced image quality, and inhomogeneous sensitivity throughout the cortex. We utilise magnetisation transfer to suppress the signal differentially from grey matter relative to blood so that the local increase in blood volume associated with brain activation (mainly occurring in the arterioles and capillaries) will increase the measured signal. Arterial blood contrast (ABC) is additive to the residual BOLD effect, but will have its maximum value at the time of excitation. We measured brain activation using combined ABC and residual BOLD contrast at different times post-excitation and compared this to BOLD data acquired under otherwise identical conditions. We conclude that using ABC and measuring shortly after excitation gives comparable sensitivity to standard BOLD but will provide greater efficiency, spatial specificity, improved image quality, and lower inter-subject variability. ABC offers new perspectives for performing functional MRI.

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