Pregnane Steroids and Short-Term Neural Plasticity

2008 ◽  
pp. 187-200
Author(s):  
Yuri B. Saalmann ◽  
Mike B. Calford
Keyword(s):  
Neural Plasticity ◽  
Short Term

Perceptual Learning Induced by Short-Term Training with Visual Stimuli: Effects of Retinal Position and Stimulus Type

2011 ◽  
Vol 22 (4) ◽  
pp. 257-262
Author(s):  
Wolfgang Skrandies
Keyword(s):  
Perceptual Learning ◽  
Neural Plasticity ◽  
Discrimination Performance ◽  
Short Term ◽  
Retinal Position ◽  
Perceptual Training ◽  
Forced Choice Task ◽  
Improved Performance ◽  
Training Control ◽  
And Training

We investigated perceptual learning in 85 healthy adults with stereoscopic information contained in dynamic random dot stimuli or with vernier targets. Stimuli were flashed simultaneously at 8 locations at an eccentricity of 1.15° or 2.3°, and subjects had to detect a target in an “8 Alternative Forced Choice” task. For training at a given eccentricity stimuli at the other eccentricity served as a “no training” control. Viewing of visual targets for about 20 minutes resulted in a significant increase of discrimination performance only for the trained stimuli (significant interaction between training and time). Thus, learning is position specific: improved performance can be demonstrated only when test and training stimuli are presented to the same retinal areas. In combination with our earlier electrophysiological results, this study illustrates how perceptual training induces stimulus and visual field specific neural plasticity in adults.

scholarly journals The Effects of Short-term and Long-term Learning on the Responses of Lateral Intraparietal Neurons to Visually Presented Objects

2015 ◽  
Vol 27 (7) ◽  
pp. 1360-1375 ◽  
Author(s):  
Heida M. Sigurdardottir ◽  
David L. Sheinberg
Keyword(s):  
Neural Plasticity ◽  
Spatial Location ◽  
Neural Responses ◽  
Short Term ◽  
Visual Objects ◽  
Visual Orienting ◽  
Different Shapes ◽  
Visual Onset ◽  
Spatial Locations

The lateral intraparietal area (LIP) is thought to play an important role in the guidance of where to look and pay attention. LIP can also respond selectively to differently shaped objects. We sought to understand to what extent short-term and long-term experience with visual orienting determines the responses of LIP to objects of different shapes. We taught monkeys to arbitrarily associate centrally presented objects of various shapes with orienting either toward or away from a preferred spatial location of a neuron. The training could last for less than a single day or for several months. We found that neural responses to objects are affected by such experience, but that the length of the learning period determines how this neural plasticity manifests. Short-term learning affects neural responses to objects, but these effects are only seen relatively late after visual onset; at this time, the responses to newly learned objects resemble those of familiar objects that share their meaning or arbitrary association. Long-term learning affects the earliest bottom–up responses to visual objects. These responses tend to be greater for objects that have been associated with looking toward, rather than away from, LIP neurons' preferred spatial locations. Responses to objects can nonetheless be distinct, although they have been similarly acted on in the past and will lead to the same orienting behavior in the future. Our results therefore indicate that a complete experience-driven override of LIP object responses may be difficult or impossible. We relate these results to behavioral work on visual attention.

scholarly journals Individual differences in frontoparietal plasticity in humans

2021 ◽  
Author(s):  
Austin L Boroshok ◽  
Anne T Park ◽  
Panagiotis Fotiadis ◽  
Gerardo H Velasquez ◽  
Ursula A Tooley ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Individual Differences ◽  
Functional Connectivity ◽  
Animal Models ◽  
Neural Plasticity ◽  
Resting State ◽  
Response Times ◽  
Resting State Functional Connectivity ◽  
Short Term ◽  
Complex Cognition

Neuroplasticity, defined as the brain's ability to change in response to its environment, has been extensively studied at the cellular and molecular levels. Work in animal models suggests that stimulation to the ventral tegmental area (VTA) enhances plasticity, and that myelination constrains plasticity. Little is known, however, about whether proxy measures of these properties in the human brain are associated with learning. Here we investigated the plasticity of the frontoparietal system (FPS), which supports complex cognition. We asked whether VTA resting-state functional connectivity and myelin map (T1-w/T2-w ratio) values predicted learning after short-term training on a FPS-dependent task: the adaptive n-back (n = 46, ages 18-25). We found that stronger connectivity between VTA and lateral prefrontal cortex at baseline predicted greater improvements in accuracy. Lower myelin map values predicted improvement in response times, but not accuracy. Our findings suggest that proxy markers of neural plasticity can predict learning in humans.

Motor Cortical Measures of Use-Dependent Plasticity Are Graded From Distal to Proximal in the Human Upper Limb

2007 ◽  
Vol 98 (6) ◽  
pp. 3230-3241 ◽  
Author(s):  
Matthew A. Krutky ◽  
Eric J. Perreault
Keyword(s):  
Upper Limb ◽  
Neural Plasticity ◽  
Index Finger ◽  
Motor Evoked Potentials ◽  
Neural Pathways ◽  
Short Term ◽  
Short Term Plasticity ◽  
Repetitive Movements ◽  
Before And After ◽  
Human Upper Limb

In humans, it is well established that practicing simple, repetitive movements with the distal upper limb induces short-term plasticity in the neural pathways that control training. It is unknown how the neural response to similar training at more proximal joints differs. The purpose of this study was to quantify how ballistic training at proximal and distal upper limb joints influences measures of corticomotor plasticity. To accomplish this goal, we had subjects repetitively practice simple movements for 30 min using the index finger, wrist, or elbow. Before and after training, transcranial magnetic stimulation (TMS) was used to activate the corticomotor pathways innervating the trained joint. We assessed the effect of training by quantifying changes in TMS-elicited joint movements and motor-evoked potentials in the training agonists and antagonists. These measures of training-induced neural plasticity were graded from distal to proximal in the upper limb. Training had the greatest immediate effect on the pathways controlling the index finger and this effect decreased for more proximal joints. Our results suggest that the relative sizes and properties of the cortical areas controlling the proximal and distal upper limb influence the effect of training on the corticomotor pathways. These results have implications for how training influences the neural pathways controlling movement in the proximal and distal portions of the human upper limb and the degree to which these effects can be quantified using TMS.

scholarly journals Altered short-term neural plasticity related to schizotypal traits: Evidence from visual adaptation

2019 ◽  
Vol 207 ◽  
pp. 48-57 ◽  
Author(s):  
Katharine N. Thakkar ◽  
Anna Antinori ◽  
Olivia L. Carter ◽  
Jan W. Brascamp
Keyword(s):  
Neural Plasticity ◽  
Visual Adaptation ◽  
Short Term

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural Changes of Canine Kidneys During 24-Hour Perfusion on a LI-400 Preservation System

1971 ◽  
Vol 29 ◽  
pp. 316-317
Author(s):  
M. O. Magnusson ◽  
D. G. Osborne ◽  
T. Shimoji ◽  
W. S. Kiser ◽  
W. A. Hawk
Keyword(s):  
Electron Microscopy ◽  
Electrolyte Solution ◽  
Ultrastructural Changes ◽  
Midline Incision ◽  
Short Term ◽  
Pentobarbital Anesthesia ◽  
Pulsatile Perfusion

Short term experimental and clinical preservation of kidneys is presently best accomplished by hypothermic continuous pulsatile perfusion with cryoprecipitated and millipore filtered plasma. This study was undertaken to observe ultrastructural changes occurring during 24-hour preservation using the above mentioned method.A kidney was removed through a midline incision from healthy mongrel dogs under pentobarbital anesthesia. The kidneys were flushed immediately after removal with chilled electrolyte solution and placed on a LI-400 preservation system and perfused at 8-10°C. Serial kidney biopsies were obtained at 0-½-1-2-4-8-16 and 24 hours of preservation. All biopsies were prepared for electron microscopy. At the end of the preservation period the kidneys were autografted.

Polychlorinated biphenyl induced hepatocyte alterations

1987 ◽  
Vol 45 ◽  
pp. 716-717
Author(s):  
D.N. Collins ◽  
J.N. Turner ◽  
K.O. Brosch ◽  
R.F. Seegal
Keyword(s):  
Lipid Droplets ◽  
Wistar Rats ◽  
Homovanillic Acid ◽  
Polychlorinated Biphenyl ◽  
Corn Oil ◽  
Environmental Pollutants ◽  
Short Term ◽  
Pcb Congeners ◽  
Urinary Levels ◽  
The Brain

Polychlorinated biphenyls (PCBs) are a ubiquitous class of environmental pollutants with toxic and hepatocellular effects, including accumulation of fat, proliferated smooth endoplasmic recticulum (SER), and concentric membrane arrays (CMAs) (1-3). The CMAs appear to be a membrane storage and degeneration organelle composed of a large number of concentric membrane layers usually surrounding one or more lipid droplets often with internalized membrane fragments (3). The present study documents liver alteration after a short term single dose exposure to PCBs with high chlorine content, and correlates them with reported animal weights and central nervous system (CNS) measures. In the brain PCB congeners were concentrated in particular regions (4) while catecholamine concentrations were decreased (4-6). Urinary levels of homovanillic acid a dopamine metabolite were evaluated (7).Wistar rats were gavaged with corn oil (6 controls), or with a 1:1 mixture of Aroclor 1254 and 1260 in corn oil at 500 or 1000 mg total PCB/kg (6 at each level).

Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity

1987 ◽  
Vol 45 ◽  
pp. 934-935
Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda
Keyword(s):  
Cell Proliferation ◽  
Liver Function ◽  
Chronic Inflammation ◽  
Foam Cell ◽  
Term Effect ◽  
Short Term ◽  
Drug Induced ◽  
Experimental Induction ◽  
Tissue Alterations ◽  
Toxic Responses

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

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