scholarly journals CA3 Mossy Fiber Connections: Giant Synapses that Gain Control

Neuron ◽  
2013 ◽  
Vol 77 (1) ◽  
pp. 4-6 ◽  
Author(s):  
Thomas E. Chater ◽  
Yukiko Goda
Keyword(s):  
Mossy Fiber ◽  
Gain Control ◽  
Giant Synapses

LTP Regulates Burst Initiation and Frequency at Mossy Fiber–Granule Cell Synapses of Rat Cerebellum: Experimental Observations and Theoretical Predictions

2006 ◽  
Vol 95 (2) ◽  
pp. 686-699 ◽  
Author(s):  
Thierry Nieus ◽  
Elisabetta Sola ◽  
Jonathan Mapelli ◽  
Elena Saftenku ◽  
Paola Rossi ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Granule Cell ◽  
Mossy Fiber ◽  
Gain Control ◽  
Long Term Potentiation ◽  
Receptor Activation ◽  
Excitatory Postsynaptic Potential ◽  
Release Probability ◽  
Whole Cell Patch Clamp ◽  
Nmda Current

Long-term potentiation (LTP) is a synaptic change supposed to provide the cellular basis for learning and memory in brain neuronal circuits. Although specific LTP expression mechanisms could be critical to determine the dynamics of repetitive neurotransmission, this important issue remained largely unexplored. In this paper, we have performed whole cell patch-clamp recordings of mossy fiber–granule cell LTP in acute rat cerebellar slices and studied its computational implications with a mathematical model. During LTP, stimulation with short impulse trains at 100 Hz revealed earlier initiation of granule cell spike bursts and a smaller nonsignificant spike frequency increase. In voltage-clamp recordings, short AMPA excitatory postsynaptic current (EPSC) trains showed short-term facilitation and depression and a sustained component probably generated by spillover. During LTP, facilitation disappeared, depression accelerated, and the sustained current increased. The N-methyl-d-aspartate (NMDA) current also increased. In agreement with a presynaptic expression caused by increased release probability, similar changes were observed by raising extracellular [Ca2+]. A mathematical model of mossy fiber–granule cell neurotransmission showed that increasing release probability efficiently modulated the first-spike delay. Glutamate spillover, by causing tonic NMDA and AMPA receptor activation, accelerated excitatory postsynaptic potential (EPSP) temporal summation and maintained a sustained spike discharge. The effect of increasing neurotransmitter release could not be replicated by increasing receptor conductance, which, like postsynaptic manipulations enhancing intrinsic excitability, proved very effective in raising granule cell output frequency. Independent regulation of spike burst initiation and frequency during LTP may provide mechanisms for temporal recoding and gain control of afferent signals at the input stage of cerebellar cortex.

Video-Enhanced Microscopy--Better Visibility of Plant Cell Structures

1982 ◽  
Vol 40 ◽  
pp. 182-185
Author(s):  
N.S. Allen ◽  
R.D. Allen
Keyword(s):  
Diffraction Pattern ◽  
Theoretical Basis ◽  
Numerical Aperture ◽  
Gain Control ◽  
Control Unit ◽  
Camera Control ◽  
Variable Gain ◽  
Contrast Method ◽  
Fine Detail ◽  
Cell Structures

Various methods of video-enhanced microscopy combine TV cameras with light microscopes creating images with improved resolution, contrast and visibility of fine detail, which can be recorded rapidly and relatively inexpensively. The AVEC (Allen Video-enhanced Contrast) method avoids polarizing rectifiers, since the microscope is operated at retardations of λ/9- λ/4, where no anomaly is seen in the Airy diffraction pattern. The iris diaphram is opened fully to match the numerical aperture of the condenser to that of the objective. Under these conditions, no image can be realized either by eye or photographically. Yet the image becomes visible using the Hamamatsu C-1000-01 binary camera, if the camera control unit is equipped with variable gain control and an offset knob (which sets a clamp voltage of a D.C. restoration circuit). The theoretical basis for these improvements has been described.

The Reaction of Brain Structures with OsO4-Zinc-Iodide Stain

1971 ◽  
Vol 29 ◽  
pp. 272-273
Author(s):  
Werner J. Niklowitz
Keyword(s):  
Electron Microscope ◽  
Structural Changes ◽  
Mossy Fiber ◽  
Toxic Metal ◽  
Staining Technique ◽  
Brain Structures ◽  
Oxidase Inhibitor ◽  
Fiber Layer ◽  
Hippocampal Tissue ◽  
Zinc Iodide

After intoxication of rabbits with certain substances such as convulsant agents (3-acetylpyridine), centrally acting drugs (reserpine), or toxic metal compounds (tetraethyl lead) a significant observation by phase microscope is the loss of contrast of the hippocampal mossy fiber layer. It has been suggested that this alteration, as well as changes seen with the electron microscope in the hippocampal mossy fiber boutons, may be related to a loss of neurotransmitters. The purpose of these experiments was to apply the OsO4-zinc-iodide staining technique to the study of these structural changes since it has been suggested that OsO4-zinc-iodide stain reacts with neurotransmitters (acetylcholine, catecholamines).Domestic New Zealand rabbits (2.5 to 3 kg) were used. Hippocampal tissue was removed from normal and experimental animals treated with 3-acetylpyridine (antimetabolite of nicotinamide), reserpine (anti- hypertensive/tranquilizer), or iproniazid (antidepressant/monamine oxidase inhibitor). After fixation in glutaraldehyde hippocampal tissue was treated with OsO4-zinc-iodide stain and further processed for phase and electron microscope studies.

Orienting and Focusing in Voluntary and Involuntary Visuospatial Attention Conditions

2010 ◽  
Vol 24 (3) ◽  
pp. 198-209 ◽  
Author(s):  
Yan Wang ◽  
Jianhui Wu ◽  
Shimin Fu ◽  
Yuejia Luo
Keyword(s):  
Gain Control ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Involuntary Attention ◽  
Attention Condition ◽  
Voluntary Attention ◽  
Visual Spatial ◽  
Related Potentials ◽  
Underlying Mechanisms

In the present study, we used event-related potentials (ERPs) and behavioral measurements in a peripherally cued line-orientation discrimination task to investigate the underlying mechanisms of orienting and focusing in voluntary and involuntary attention conditions. Informative peripheral cue (75% valid) with long stimulus onset asynchrony (SOA) was used in the voluntary attention condition; uninformative peripheral cue (50% valid) with short SOA was used in the involuntary attention condition. Both orienting and focusing were affected by attention type. Results for attention orienting in the voluntary attention condition confirmed the “sensory gain control theory,” as attention enhanced the amplitude of the early ERP components, P1 and N1, without latency changes. In the involuntary attention condition, compared with invalid trials, targets in the valid trials elicited larger and later contralateral P1 components, and smaller and later contralateral N1 components. Furthermore, but only in the voluntary attention condition, targets in the valid trials elicited larger N2 and P3 components than in the invalid trials. Attention focusing in the involuntary attention condition resulted in larger P1 components elicited by targets in small-cue trials compared to large-cue trials, whereas in the voluntary attention condition, larger P1 components were elicited by targets in large-cue trials than in small-cue trials. There was no interaction between orienting and focusing. These results suggest that orienting and focusing of visual-spatial attention are deployed independently regardless of attention type. In addition, the present results provide evidence of dissociation between voluntary and involuntary attention during the same task.

The process of investigating Diocesan Curia in Lublin by the PRL’s apparatus of repression in the years 1946-1974

2013 ◽  
Vol 67 (1) ◽  
Author(s):  
Elżbieta Kosobudzka
Keyword(s):  
Catholic Church ◽  
Gain Control ◽  
Source Analysis ◽  
Secret Police ◽  
Personal Lives ◽  
Catholic Clergy ◽  
Recorded Data ◽  
The Government ◽  
Operational Activities ◽  
Intensive Surveillance

SUMMARYThe article below focuses on the source analysis of the process of investigating Diocesan Curia in Lublin in the years 1946-1947, during the period when two Lublin ordinaries were in charge: Bishop Stefan Wyszyński (1946-1948) and Bishop Piotr Kałwa (1949-1974). Diocesan Curia, as the most important institution in the Church administrative hierarchy, was subject to intensive surveillance by PRL’s apparatus of repression.At the beginning, the process of investigating the management structure on the diocese level was not conducted by specially selected departments but was performed as a part of broadly conceived actions directed against Catholic clergy. In the years 1946-1948,when bishop Stefan Wyszyński was in charge, operational activities against the clergy and the bishops were led by 5th Section of 5th Department of Voivodeship Public Security Office (Sekcja V Wydziału V Wojewódzkiego Urzędu Bezpieczeństwa) in Lublin (until the February of 1953). It can be inferred from the recorded data that until 1949 the Diocesan Curia’s circle in Lublin was very poorly uncovered by Polish communist secret police and their activity amounted only to gathering and verifying data received from informants. The shortage of well-trained agents prevented taking more intensive actions against Bishop Wyszyński and Diocesan Curia in Lublin.In the years 1949-1974, when Bishop Piotr Kałwa was in charge, the 5th Section of the 5th Department of VPSO continued their operational activities aimed against the Lublin’s Curia. In 1953 a new department was created on the basis of 5th Section. The so-called 11th Department took over the entirety of cases pertaining to the Catholic Church. In 1955 the 11th Department was transformed into 6th Department of VPSO in Lublin. 3rd Department of VPSO in Lublin and 1st Section of 6th Department of Polish communist secret police of Voivodeship Polish Citizen Militia Headquarters in Lublin (referat Służby Bezpieczeństwa w Komendzie Wojewódzkiej Milicji Obywatelskiej), respectively, also conducted investigation activities concerning the bishops and Curia.As of 1949, the Diocesan Curia in Lublin was subject to intensive surveillance by the PRL’s security service apparatus. Its main aim at that point was to restrict the Curia’s activity so as to gain control over it. In order to achieve that, the activity of Curial employees and bishops was documented and revealed. Additionally, the conflicts between the bishops, Curial employees and KUL’s management were incited and deepened. What is more, the secret police attentively scrutinized bishops’ and Curial employees’ personal lives in order to gather compromising data, gained secret collaborators (47 secret agents were involved in the process) and limited Curia employees’ departures for studies abroad. Almost every type of operation activities was used against Bishop Piotr Kałwa. The secret police applied phone tapping, bugging, surveillance, reading mail and sending anonymous letters in order to undermine his authority. What is more, the secret police tried to set bishop Kałwa at variance with Primate Wyszyński. However, these actions did not change Bishops Kałwa’s stance who, until his death, unwaveringly defended the Catholic Church’s independence from the government.

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