scholarly journals Neurons in V1, V2, and PMLS of Cat Cortex Are Speed Tuned But Not Acceleration Tuned: The Influence of Motion Adaptation

2006 ◽  
Vol 95 (2) ◽  
pp. 660-673 ◽  
Author(s):  
N.S.C. Price ◽  
N. A. Crowder ◽  
M. A. Hietanen ◽  
M. R. Ibbotson
Keyword(s):  
Ramp Rate ◽  
Brain Areas ◽  
Response Latencies ◽  
Motion Adaptation ◽  
Specific Adaptation ◽  
Cortical Areas ◽  
Acceleration Rate ◽  
Acceleration And Deceleration ◽  
Lateral Suprasylvian Area ◽  
Sustained Responses

We studied neurons in areas V1, V2, and posteromedial lateral suprasylvian area (PMLS) of anesthetized cats, assessing their speed tuning using steps to constant speeds and acceleration and deceleration tuning using speed ramps. The results show that the speed tuning of neurons in all three cortical areas is highly dependent on prior motion history, with early responses during speed steps tuned to higher speeds than later responses. The responses to speed ramps are profoundly influenced by speed-dependent response latencies and ongoing changes in neuronal speed tuning due to adaptation. Acceleration evokes larger transient and sustained responses than subsequent deceleration of the same rate with this disparity increasing with ramp rate. Consequently, there was little correlation between preferred speeds measured using speed steps, acceleration or deceleration. From 146 recorded cells, the proportion of cells that were clearly speed tuned ranged from 69 to 100% across the three brain areas. However, only 13 cells showed good skewed Gaussian fits and systematic variation in their responses to a range of accelerations. Although suggestive of acceleration coding, this apparent tuning was attributable to a cell's speed tuning and the different stimulus durations at each acceleration rate. Thus while the majority of cells showed speed tuning, none unequivocally showed acceleration tuning. The results are largely consistent with an existing model that predicts responses to accelerating stimuli developed for macaque MT, which showed that the responses to acceleration can be decoded if adaptation is taken into account. However, the present results suggest future models should include stimulus-specific adaptation and speed-dependent response latencies.

Engaging regularly with fiction influences connectivity in cortical areas for language and mentalizing

2017 ◽  
Author(s):  
Roel M. Willems ◽  
Franziska Hartung
Keyword(s):  
Functional Connectivity ◽  
Time Course ◽  
Language Skills ◽  
Brain Regions ◽  
Brain Areas ◽  
Daily Lives ◽  
Cortical Areas ◽  
Social Abilities ◽  
Behavioral Evidence ◽  
Amount Of Reading

Behavioral evidence suggests that engaging with fiction is positively correlated with social abilities. The rationale behind this link is that engaging with fictional narratives offers a ‘training modus’ for mentalizing and empathizing. We investigated the influence of the amount of reading that participants report doing in their daily lives, on connections between brain areas while they listened to literary narratives. Participants (N=57) listened to two literary narratives while brain activation was measured with fMRI. We computed time-course correlations between brain regions, and compared the correlation values from listening to narratives to listening to reversed speech. The between-region correlations were then related to the amount of fiction that participants read in their daily lives. Our results show that amount of fiction reading is related to functional connectivity in areas known to be involved in language and mentalizing. This suggests that reading fiction influences social cognition as well as language skills.

scholarly journals Reducing Lateral Vibrations of a Rotor Passing Through Critical Speeds by Acceleration Scheduling

1997 ◽  
Author(s):  
Knox T. Millsaps ◽  
Gregory L. Reed
Keyword(s):  
Critical Speed ◽  
Vibrational Energy ◽  
Lumped Parameter Model ◽  
Integration Scheme ◽  
Lateral Vibrations ◽  
Acceleration Rate ◽  
Lumped Parameter ◽  
Numerical Integration Scheme ◽  
Single Disk ◽  
Acceleration And Deceleration

A method is presented for reducing the lateral response of an imbalanced rotor accelerating or decelerating through its first lateral bending critical speed by using a variable acceleration rate. A lumped parameter model along with a numerical integration scheme is used to simulate the response of a simply supported, single disk rotor during fast acceleration and deceleration through critical speed. The results indicate that the maximum response and/or the total vibrational energy of a rotor passing through the critical speed can be reduced significantly by using a variable acceleration schedule. That is, reducing the acceleration rate after the nominal critical speed is passed. These predictions were verified experimentally for a single disk rotor.

scholarly journals No evidence for motor recovery-related cortical reorganization after stroke using resting-state fMRI

2019 ◽  
Author(s):  
Meret Branscheidt ◽  
Naveed Ejaz ◽  
Jing Xu ◽  
Mario Widmer ◽  
Michelle D. Harran ◽  
...  
Keyword(s):  
Resting State ◽  
Resting State Fmri ◽  
Motor Recovery ◽  
Cortical Reorganization ◽  
Behavioral Recovery ◽  
Brain Areas ◽  
Data Set ◽  
Post Stroke ◽  
Cortical Areas ◽  
One Year

AbstractCortical reorganization has been suggested as mechanism for recovery after stroke. It has been proposed that a form of cortical reorganization (changes in functional connectivity between brain areas) can be assessed with resting-state fMRI. Here we report the largest longitudinal data-set in terms of overall sessions in 19 patients with subcortical stroke and 11 controls. Patients were imaged up to 5 times over one year. We found no evidence for post-stroke cortical reorganization despite substantial behavioral recovery. These results could be construed as questioning the value of resting-state imaging. Here we argue instead that they are consistent with other emerging reasons to challenge the idea of motor recovery-related cortical reorganization post-stroke when conceived as changes in connectivity between cortical areas.

Julich-Brain: A 3D probabilistic atlas of the human brain’s cytoarchitecture

Science ◽  
2020 ◽  
Vol 369 (6506) ◽  
pp. 988-992
Author(s):  
Katrin Amunts ◽  
Hartmut Mohlberg ◽  
Sebastian Bludau ◽  
Karl Zilles
Keyword(s):  
Data Processing ◽  
Modeling And Simulation ◽  
Basic Principle ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Brain Areas ◽  
Cortical Maps ◽  
Cortical Areas ◽  
Probabilistic Atlas ◽  
Subcortical Nuclei

Cytoarchitecture is a basic principle of microstructural brain parcellation. We introduce Julich-Brain, a three-dimensional atlas containing cytoarchitectonic maps of cortical areas and subcortical nuclei. The atlas is probabilistic, which enables it to account for variations between individual brains. Building such an atlas was highly data- and labor-intensive and required the development of nested, interdependent workflows for detecting borders between brain areas, data processing, provenance tracking, and flexible execution of processing chains to handle large amounts of data at different spatial scales. Full cortical coverage was achieved by the inclusion of gap maps to complement cortical maps. The atlas is dynamic and will be adapted as mapping progresses; it is openly available to support neuroimaging studies as well as modeling and simulation; and it is interoperable, enabling connection to other atlases and resources.

Visual response latencies in striate cortex of the macaque monkey

1992 ◽  
Vol 68 (4) ◽  
pp. 1332-1344 ◽  
Author(s):  
J. H. Maunsell ◽  
J. R. Gibson
Keyword(s):  
Striate Cortex ◽  
Macaque Monkey ◽  
Cortical Activation ◽  
Visual Response ◽  
Neuronal Responses ◽  
Transient Responses ◽  
Response Latencies ◽  
Layer 4 ◽  
Sustained Responses ◽  
Made In

1. Many lines of evidence suggest that signals relayed by the magnocellular and parvocellular subdivisions of the primate lateral geniculate nucleus (LGN) maintain their segregation in cortical processing. We have examined two response properties of units in the striate cortex of macaque monkeys, latency and transience, with the goal of assessing whether they might be used to infer specific geniculate contributions. Recordings were made from 298 isolated units and 1,129 multiunit sites in the striate cortex in four monkeys. Excitotoxin lesions that selectively affected one or the other LGN subdivision were made in three animals to demonstrate directly the magnocellular and parvocellular contributions. An additional 435 single units and 551 multiunit sites were recorded after the ablations. 2. Most units in striate cortex had visual response latencies in the range of 30-50 ms under the stimulus conditions used. The earliest neuronal responses in striate cortex differed appreciably between individuals. The shortest latency recorded in the four animals ranged from 20 to 31 ms. Comparable values were obtained from both single unit and multiunit sites. After lesions were made in the magnocellular subdivision of the LGN in two animals, the shortest response latencies were 7 and 10 ms later than before the ablations. A larger lesion in the parvocellular subdivision of another animal produced no such shift. Thus it appears that the first 7-10 ms of cortical activation can be attributed to activation relayed by the magnocellular layers of the LGN. 3. The units with the shortest latencies were all found in layers 4C or 6 and their responses were among the most transient in striate cortex. Furthermore, their responses all showed a pronounced periodicity at a frequency of 50-100 Hz. This periodicity was stimulus locked, and the responses of all short-latency units oscillated in phase. 4. An index of response transience was computed for the units recorded in striate cortex. The distribution of this index was unimodal and gave no suggestion of distinct contributions from the geniculate subdivisions. Magnocellular and the parvocellular lesions affected the overall transience of responses in striate cortex. The changes, however, were very small; extremely transient responses and extremely sustained responses survived both types of lesions. 5. A characteristic profile was observed in the response latencies in superficial layers. Latencies appeared to increase monotonically from layer 4 toward the surface of cortex, with the most superficial neurons not becoming active until 15 ms after responses were observed in layer 4C.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Structural diverseness of neurons between brain areas and between cases

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ryuta Mizutani ◽  
Rino Saiga ◽  
Yoshiro Yamamoto ◽  
Masayuki Uesugi ◽  
Akihisa Takeuchi ◽  
...  
Keyword(s):  
Geometric Analysis ◽  
Three Dimensional ◽  
Superior Temporal Gyrus ◽  
Anterior Cingulate ◽  
Nanometer Scale ◽  
Brain Areas ◽  
Brain Functions ◽  
Cortical Areas ◽  
Structural Differences ◽  
And Control

AbstractThe cerebral cortex is composed of multiple cortical areas that exert a wide variety of brain functions. Although human brain neurons are genetically and areally mosaic, the three-dimensional structural differences between neurons in different brain areas or between the neurons of different individuals have not been delineated. Here we report a nanometer-scale geometric analysis of brain tissues of the superior temporal gyrus of schizophrenia and control cases. The results of the analysis and a comparison with results for the anterior cingulate cortex indicated that (1) neuron structures are significantly dissimilar between brain areas and that (2) the dissimilarity varies from case to case. The structural diverseness was mainly observed in terms of the neurite curvature that inversely correlates with the diameters of the neurites and spines. The analysis also revealed the geometric differences between the neurons of the schizophrenia and control cases. The schizophrenia cases showed a thin and tortuous neuronal network compared with the controls, suggesting that the neuron structure is associated with the disorder. The area dependency of the neuron structure and its diverseness between individuals should represent the individuality of brain functions.

scholarly journals Correlated structure of neuronal firing in macaque visual cortex limits information for binocular depth discrimination

2021 ◽  
Author(s):  
Jackson Earle Tulonen Smith ◽  
Andrew J Parker
Keyword(s):  
Theoretical Work ◽  
Temporal Scale ◽  
Neuronal Firing ◽  
Brain Areas ◽  
Cortical Areas ◽  
Depth Discrimination ◽  
Binocular Stereo ◽  
Integrative Processing ◽  
Visual Cortical ◽  
Binocular Depth

Variability in cortical neural activity potentially limits sensory discriminations. Theoretical work shows that information required to discriminate two similar stimuli is limited by the correlation structure of cortical variability. We investigated these information-limiting correlations by recording simultaneously from visual cortical areas V1 and V4 in macaque monkeys, performing a binocular, stereo-depth discrimination task. Within both areas, noise correlations on a rapid temporal scale (20-30ms) were stronger for neuron-pairs with similar selectivity for binocular depth, meaning that these correlations potentially limit information for making the discrimination. Between-area correlations (V1 to V4) were different, being weaker for neuron pairs with similar tuning, and having a slower temporal scale (100+ms). Fluctuations in these information-limiting correlations just prior to the detection event were associated with changes in behavioral accuracy. Although these correlations limit the recovery of information about sensory targets, their impact may be curtailed by integrative processing of signals across multiple brain areas.

Reducing Lateral Vibrations of a Rotor Passing Through Critical Speeds by Acceleration Scheduling

1998 ◽  
Vol 120 (3) ◽  
pp. 615-620 ◽  
Author(s):  
K. T. Millsaps ◽  
G. L. Reed
Keyword(s):  
Critical Speed ◽  
Vibrational Energy ◽  
Lumped Parameter Model ◽  
Integration Scheme ◽  
Lateral Vibrations ◽  
Acceleration Rate ◽  
Lumped Parameter ◽  
Numerical Integration Scheme ◽  
Single Disk ◽  
Acceleration And Deceleration

A method is presented for reducing the lateral response of an imbalanced rotor accelerating or decelerating through its first lateral bending critical speed by using a variable acceleration rate. A lumped parameter model along with a numerical integration scheme is used to simulate the response of a simply supported, single disk rotor during fast acceleration and deceleration through critical speed. The results indicate that the maximum response and/or the total vibrational energy of a rotor passing through the critical speed can be reduced significantly by using a variable acceleration schedule. That is, reducing the acceleration rate after the nominal critical speed is passed. These predictions were verified experimentally for a single disk rotor.

scholarly journals Mass spectrometry imaging identifies abnormally elevated brain l-DOPA levels and extrastriatal monoaminergic dysregulation in l-DOPA–induced dyskinesia

2021 ◽  
Vol 7 (2) ◽  
pp. eabe5948
Author(s):  
Elva Fridjonsdottir ◽  
Reza Shariatgorji ◽  
Anna Nilsson ◽  
Theodosia Vallianatou ◽  
Luke R. Odell ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Side Effects ◽  
Mass Spectrometry Imaging ◽  
Brain Regions ◽  
Stria Terminalis ◽  
Brain Areas ◽  
Bed Nucleus ◽  
Neuronal Signaling ◽  
Cortical Areas ◽  
The Brain

l-DOPA treatment for Parkinson’s disease frequently leads to dyskinesias, the pathophysiology of which is poorly understood. We used MALDI-MSI to map the distribution of l-DOPA and monoaminergic pathways in brains of dyskinetic and nondyskinetic primates. We report elevated levels of l-DOPA, and its metabolite 3-O-methyldopa, in all measured brain regions of dyskinetic animals and increases in dopamine and metabolites in all regions analyzed except the striatum. In dyskinesia, dopamine levels correlated well with l-DOPA levels in extrastriatal regions, such as hippocampus, amygdala, bed nucleus of the stria terminalis, and cortical areas, but not in the striatum. Our results demonstrate that l-DOPA–induced dyskinesia is linked to a dysregulation of l-DOPA metabolism throughout the brain. The inability of extrastriatal brain areas to regulate the formation of dopamine during l-DOPA treatment introduces the potential of dopamine or even l-DOPA itself to modulate neuronal signaling widely across the brain, resulting in unwanted side effects.

scholarly journals Cortical Complexity in Anorexia Nervosa: A Fractal Dimension Analysis

2020 ◽  
Vol 9 (3) ◽  
pp. 833 ◽  
Author(s):  
Enrico Collantoni ◽  
Christopher R. Madan ◽  
Paolo Meneguzzo ◽  
Iolanna Chiappini ◽  
Elena Tenconi ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Fractal Dimension ◽  
Brain Areas ◽  
Opposite Pattern ◽  
Cortical Areas ◽  
Duration Of Illness ◽  
Dimension Analysis ◽  
High Resolution Mri ◽  
Fractal Dimension Analysis ◽  
Psychiatric Conditions

Fractal Dimension (FD) has shown to be a promising means to describe the morphology of cortical structures across different neurologic and psychiatric conditions, displaying a good sensitivity in capturing atrophy processes. In this study, we aimed at exploring the morphology of cortical areas by means of FD in 58 female patients with Anorexia Nervosa (AN) (38 currently underweight and 20 fully recovered) and 38 healthy controls (HC). All participants underwent high-resolution MRI. Surface extraction was completed using FreeSurfer, FD was computed using the calcFD toolbox. The whole cortex mean FD value was lower in acute AN patients compared to HC (p < 0.001). Recovered AN patients did not show differences in the global FD when compared to HC. However, some brain areas showed higher FD in patients than controls, while others showed the opposite pattern. Parietal regions showed lower FD in both AN groups. In acute AN patients, the FD correlated with age (p < 0.001), body mass index (p = 0.019) and duration of illness (p = 0.011). FD seems to represent a feasible method to explore cortical complexity in patients with AN since it demonstrated to be sensitive to the effects of both severity and duration of malnutrition.

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