Synaptic transmission and recognition memory: Time course of changes in N-methyl-D-aspartate receptors after imprinting.

1991 ◽  
Vol 105 (2) ◽  
pp. 289-294 ◽  
Author(s):  
B. J. McCabe ◽  
G. Horn
Keyword(s):  
Recognition Memory ◽  
Synaptic Transmission ◽  
Time Course ◽  
Memory Time

From Perception to Recognition Memory: Time Course and Lateralization of Neural Substrates of Word and Abstract Picture Processing

2011 ◽  
Vol 23 (4) ◽  
pp. 782-800 ◽  
Author(s):  
Louis Maillard ◽  
Emmanuel J. Barbeau ◽  
Cedric Baumann ◽  
Laurent Koessler ◽  
Christian Bénar ◽  
...  
Keyword(s):  
Recognition Memory ◽  
Cognitive Processing ◽  
Time Course ◽  
Early Stage ◽  
Hemispheric Specialization ◽  
Neural Substrates ◽  
Hemispheric Lateralization ◽  
Memory Time ◽  
Abstract Picture ◽  
Late Stages

Through study of clinical cases with brain lesions as well as neuroimaging studies of cognitive processing of words and pictures, it has been established that material-specific hemispheric specialization exists. It remains however unclear whether such specialization holds true for all processes involved in complex tasks, such as recognition memory. To investigate neural signatures of transition from perception to recognition, according to type of material (words or abstract pictures), high-resolution scalp ERPs were recorded in adult humans engaged either in categorization or in memory recognition tasks within the same experimental setup. Several steps in the process from perception to recognition were identified. Source localization showed that the early stage of perception processing (N170) takes place in the fusiform gyrus and is lateralized according to the nature of stimuli (left side for words and right side for pictures). Late stages of processing (N400/P600) corresponding to recognition are material independent and involve anterior medial-temporal and ventral prefrontal structures bilaterally. A crucial transitional process between perception (N170) and recognition (N400/P600) is reflected by the N270, an often overlooked component, which occurs in anterior rhinal cortices and shows material-specific hemispheric lateralization.

The time course of false recognition memory: Data and models

2001 ◽  
Author(s):  
Evan Heit ◽  
Noellie Brockdorff ◽  
Koen Lamberts
Keyword(s):  
Recognition Memory ◽  
False Recognition ◽  
Time Course

scholarly journals Androgens Modulate NMDA Receptor–Mediated EPSCs in the Zebra Finch Song System

1999 ◽  
Vol 82 (5) ◽  
pp. 2221-2234 ◽  
Author(s):  
Stephanie A. White ◽  
Frederick S. Livingston ◽  
Richard Mooney
Keyword(s):  
Nmda Receptor ◽  
Synaptic Transmission ◽  
Time Course ◽  
Song Learning ◽  
Lateral Part ◽  
Spine Density ◽  
Song System ◽  
Decay Times ◽  
Soma Size

Androgens potently regulate the development of learned vocalizations of songbirds. We sought to determine whether one action of androgens is to functionally modulate the development of synaptic transmission in two brain nuclei, the lateral part of the magnocellular nucleus of the anterior neostriatum (LMAN) and the robust nucleus of the archistriatum (RA), that are critical for song learning and production. We focused on N-methyl-d-aspartate–excitatory postsynaptic currents (NMDA-EPSCs), because NMDA receptor activity in LMAN is crucial to song learning, and because the LMAN synapses onto RA neurons are almost entirely mediated by NMDA receptors. Whole cell recordings from in vitro brain slice preparations revealed that the time course of NMDA-EPSCs was developmentally regulated in RA, as had been shown previously for LMAN. Specifically, in both nuclei, NMDA-EPSCs become faster over development. We found that this developmental transition can be modulated by androgens, because testosterone treatment of young animals caused NMDA-EPSCs in LMAN and RA to become prematurely fast. These androgen-induced effects were limited to fledgling and juvenile periods and were spatially restricted, in that androgens did not accelerate developmental changes in NMDA-EPSCs recorded in a nonsong area, the Wulst. To determine whether androgens had additional effects on LMAN or RA neurons, we examined several other physiological and morphological parameters. In LMAN, testosterone affected α-amino-3-hydroxy-5-methyl-4-isoxazoleproprianate–EPSC (AMPA-EPSC) decay times and the ratio of peak synaptic glutamate to AMPA currents, as well as dendritic length and spine density but did not alter soma size or dendritic complexity. In contrast, testosterone did not affect any of these parameters in RA, which demonstrates that exogenous androgens can have selective actions on different song system neurons. These data are the first evidence for any effect of sex steroids on synaptic transmission within the song system. Our results support the idea that endogenous androgens limit sensitive periods for song learning by functionally altering synaptic transmission in song nuclei.

Rapidly Deactivating AMPA Receptors Determine Excitatory Synaptic Transmission to Interneurons in the Nucleus Tractus Solitarius From Rat

1997 ◽  
Vol 78 (1) ◽  
pp. 82-91 ◽  
Author(s):  
Stefan Titz ◽  
Bernhard U. Keller
Keyword(s):  
Synaptic Transmission ◽  
Ampa Receptor ◽  
Decay Time ◽  
Ampa Receptors ◽  
Time Course ◽  
Nucleus Tractus Solitarius ◽  
Synaptic Cleft ◽  
Excitatory Synaptic Transmission ◽  
Membrane Properties ◽  
Time Constants

Titz, Stefan and Bernhard U. Keller. Rapidly deactivating AMPA receptors determine excitatory synaptic transmission to interneurons in the nucleus tractus solitarius from rat. J. Neurophysiol. 78: 82–91, 1997. Excitatory synaptic transmission was investigated in interneurons of the parvocellular nucleus tractus solitarius (pNTS) by performing patch-clamp experiments in thin slice preparations from rat brain stem. Stimulation of single afferent fibers evoked excitatory postsynaptic currents (EPSCs) mediated by glutamate receptors of the dl-α-amino-3-hydroxy-5-methylisoxazole-propionic acid (AMPA) and N-methyl-d-aspartate types. AMPA-receptor-mediated EPSCs displayed decay time constants of 3.5 ± 1.2 (SD) ms (13 cells), which were slow compared with EPSC decay time constants in neurons of the cerebellum or hippocampus. Slow EPSC decay was not explained by dendritic filtering, because the passive membrane properties of pNTS interneurons provided favorable voltage-clamp conditions. Also, the slowness of EPSC decay did not result from slow deactivation of AMPA receptors (0.7 ± 0.2 ms, 5 cells), which was investigated during rapid application of agonist to outside-out patches. Comparison of AMPA receptor kinetics with EPSC decay time constants suggested that the slow time course of EPSCs resulted from the prolonged presence of glutamate in the synaptic cleft.

scholarly journals Is Pupil Activity Associated With the Strength of Memory Signal for Words in a Continuous Recognition Memory Paradigm?

2021 ◽  
Vol 12 ◽  
Author(s):  
Jorge Oliveira ◽  
Marta Fernandes ◽  
Pedro J. Rosa ◽  
Pedro Gamito
Keyword(s):  
Retention Interval ◽  
Recognition Memory ◽  
Pupil Size ◽  
Time Course ◽  
Recognition Performance ◽  
Recognition Task ◽  
Subjective Feeling ◽  
Consistent Finding ◽  
Pupillary Responses ◽  
Study Test

Research on pupillometry provides an increasing evidence for associations between pupil activity and memory processing. The most consistent finding is related to an increase in pupil size for old items compared with novel items, suggesting that pupil activity is associated with the strength of memory signal. However, the time course of these changes is not completely known, specifically, when items are presented in a running recognition task maximizing interference by requiring the recognition of the most recent items from a sequence of old/new items. The sample comprised 42 healthy participants who performed a visual word recognition task under varying conditions of retention interval. Recognition responses were evaluated using behavioral variables for discrimination accuracy, reaction time, and confidence in recognition decisions. Pupil activity was recorded continuously during the entire experiment. The results suggest a decrease in recognition performance with increasing study-test retention interval. Pupil size decreased across retention intervals, while pupil old/new effects were found only for words recognized at the shortest retention interval. Pupillary responses consisted of a pronounced early pupil constriction at retrieval under longer study-test lags corresponding to weaker memory signals. However, the pupil size was also sensitive to the subjective feeling of familiarity as shown by pupil dilation to false alarms (new items judged as old). These results suggest that the pupil size is related not only to the strength of memory signal but also to subjective familiarity decisions in a continuous recognition memory paradigm.

Long-term facilitation alters transmitter releasing properties at the crayfish neuromuscular junction

1986 ◽  
Vol 55 (3) ◽  
pp. 484-498 ◽  
Author(s):  
J. M. Wojtowicz ◽  
H. L. Atwood
Keyword(s):  
Neuromuscular Junction ◽  
Synaptic Transmission ◽  
Time Course ◽  
Muscle Fibers ◽  
Low Frequencies ◽  
Before And After ◽  
Binomial Parameter ◽  
Small Muscle ◽  
Long Term Facilitation

Synaptic transmission at the neuromuscular junction of the excitatory axon supplying the crayfish opener muscle was examined before and after induction of long-term facilitation (LTF) by a 10-min period of stimulation at 20 Hz. Induction of LTF led to a period of enhanced synaptic transmission, which often persisted for many hours. The enhancement was entirely presynaptic in origin, since quantal unit size and time course were not altered, and quantal content of transmission (m) was increased. LTF was not associated with any persistent changes in action potential or presynaptic membrane potential recorded in the terminal region of the excitatory axon. The small muscle fibers of the walking-leg opener muscle were almost isopotential, and all quantal events could be recorded with an intracellular microelectrode. In addition, at low frequencies of stimulation, m was small. Thus it was possible to apply a binomial model of transmitter release to events recorded from individual muscle fibers and to calculate values for n (number of responding units involved in transmission) and p (probability of transmission for the population of responding units) before and after LTF. In the majority of preparations analyzed (6/10), amplitude histograms of evoked synaptic potentials could be described by a binomial distribution with a small n and moderately high p. LTF produced a significant increase in n, while p was slightly reduced. The results can be explained by a model in which the binomial parameter n represents the number of active synapses and parameter p the mean probability of release at a synapse. Provided that a pool of initially inactive synapses exists, one can postulate that LTF involves recruitment of synapses to the active state.

Pharmacological and kinetic characterization of two functional classes of serotonergic modulation in Aplysia sensory neurons

1996 ◽  
Vol 75 (2) ◽  
pp. 855-866 ◽  
Author(s):  
L. L. Stark ◽  
A. R. Mercer ◽  
N. J. Emptage ◽  
T. J. Carew
Keyword(s):  
Synaptic Transmission ◽  
Sensory Neurons ◽  
Time Course ◽  
Behavioral Sensitization ◽  
Input Resistance ◽  
Short Term ◽  
Synaptic Facilitation ◽  
Functional Classes ◽  
Kinetics Of ◽  
Serotonergic Modulation

1. Modulation of mechanoafferent sensory neurons (SNs) by the neutrotransmitter serotonin (5HT) plays a significant role in behavioral sensitization of several withdrawal reflexes in Aplysia. The modulatory effects of 5HT on these SNs include increased excitability, increased input resistance, action potential broadening, and increased synaptic transmission. Based on a previously described dissociation of some of these modulatory effects, revealed with the 5HT-receptor antagonist, cyproheptadine, we investigated whether a similar dissociation could be found by systematically varying the concentration of the endogenous agonist, 5HT. 2. We first applied a range of 5HT concentrations to isolated pleural/pedal ganglia (containing tail SNs and tail motor neurons, respectively), and measured the magnitude of 5HT-induced modulation of spike broadening and increased excitability. The resulting dose-response curve showed that both forms of modulation increase monotonically as a function of 5HT concentration, but that excitability has a lower threshold for modulation by 5HT than does spike duration. 3. We further characterized the modulatory effects of 5HT on Aplysia SNs by comparing the time course of onset of modulation by 5HT and the time course of recovery after washout. Independent of 5HT concentration, modulation of excitability increases rapidly in the presence of 5HT and recovers rapidly (< 3 min) after washout. Similarly, input resistance increases and recovers rapidly, mirroring the profile of increased excitability. However, modulation of spike duration exhibits two profiles, dependent on 5HT concentration. Low concentrations of 5HT (0.5 and 1 microM) induce a rapid-onset and transient-recovery form of spike broadening, which resembles the kinetics of increased excitability and increased input resistance. Higher concentrations of 5HT (2.5 and 5 microM) induce a more slowly developing and prolonged-recovery form of spike broadening (> 9 min). At these higher concentrations, the recovery profile for prolonged spike broadening is significantly different from those observed for both increased excitability and increased input resistance. 4. We next compared the relationship between spike broadening and short-term synaptic facilitation. We found that significant facilitation of synaptic transmission requires a high 5HT concentration, which is comparable with that required to induce prolonged spike broadening. Similarly, the recovery profiles for spike broadening and synaptic facilitation are strikingly similar, recovering in parallel. 5. Our experiments show that the modulatory effects of 5HT in the tail SNs can be dissociated both by their sensitivity to different concentrations of 5HT and by their kinetics of serotonergic modulation. Based on these results, together with extensive evidence from other laboratories, we propose that the short-term modulatory effects of 5HT fall into two distinct functional classes. The first class, which includes excitability, input resistance, and transient spike broadening, has a low threshold for 5HT modulation and recovers rapidly. The second class, which includes prolonged spike broadening and short-term synaptic facilitation, has a higher threshold for modulation and recovers more slowly. It now will be of interest to determine the functional contribution of each of these classes to different aspects of sensitization.

Kainate receptor-mediated synaptic transmissions in the adult rodent insular cortex

2012 ◽  
Vol 108 (7) ◽  
pp. 1988-1998 ◽  
Author(s):  
Kohei Koga ◽  
Su-Eon Sim ◽  
Tao Chen ◽  
Long-Jun Wu ◽  
Bong-Kiun Kaang ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Receptor Antagonist ◽  
Ampa Receptor ◽  
Time Course ◽  
Insular Cortex ◽  
Nmda Receptor Antagonist ◽  
Functional Roles ◽  
Adult Rat ◽  
Whole Cell Patch Clamp ◽  
The Central Nervous System

Kainate (KA) receptors are expressed widely in the central nervous system and regulate both excitatory and inhibitory synaptic transmission. KA receptors play important roles in fear memory, anxiety, and pain. However, little is known about their function in synaptic transmission in the insular cortex (IC), a critical region for taste, memory, and pain. Using whole cell patch-clamp recordings, we have shown that KA receptors contribute to fast synaptic transmission in neurons in all layers of the IC. In the presence of the GABAA receptor antagonist picrotoxin, the NMDA receptor antagonist AP-5, and the selective AMPA receptor antagonist GYKI 53655, KA receptor-mediated excitatory postsynaptic currents (KA EPSCs) were revealed. We found that KA EPSCs are ∼5–10% of AMPA/KA EPSCs in all layers of the adult mouse IC. Similar results were found in adult rat IC. KA EPSCs had a significantly slower rise time course and decay time constant compared with AMPA receptor-mediated EPSCs. High-frequency repetitive stimulations at 200 Hz significantly facilitated the summation of KA EPSCs. In addition, genetic deletion of GluK1 or GluK2 subunit partially reduced postsynaptic KA EPSCs, and exposure of GluK2 knockout mice to the selective GluK1 antagonist UBP 302 could significantly reduce the KA EPSCs. These data suggest that both GluK1 and GluK2 play functional roles in the IC. Our study may provide the synaptic basis for the physiology and pathology of KA receptors in the IC-related functions.

Early Defects of GABAergic Synapses in the Brain Stem of a MeCP2 Mouse Model of Rett Syndrome

2008 ◽  
Vol 99 (1) ◽  
pp. 112-121 ◽  
Author(s):  
L. Medrihan ◽  
E. Tantalaki ◽  
G. Aramuni ◽  
V. Sargsyan ◽  
I. Dudanova ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Brain Stem ◽  
Rett Syndrome ◽  
Time Course ◽  
Molecular Mechanisms ◽  
Neurodevelopmental Disorder ◽  
Therapeutic Interventions ◽  
Ventrolateral Medulla ◽  
Diagnostic Tools ◽  
The Brain

Rett syndrome is a neurodevelopmental disorder caused by mutations in the transcriptional repressor methyl-CpG-binding protein 2 (MeCP2) and represents the leading genetic cause for mental retardation in girls. MeCP2-mutant mice have been generated to study the molecular mechanisms of the disease. It was suggested that an imbalance between excitatory and inhibitory neurotransmission is responsible for the behavioral abnormalities, although it remained largely unclear which synaptic components are affected and how cellular impairments relate to the time course of the disease. Here, we report that MeCP2 KO mice present an imbalance between inhibitory and excitatory synaptic transmission in the ventrolateral medulla already at postnatal day 7. Focusing on the inhibitory synaptic transmission we show that GABAergic, but not glycinergic, synaptic transmission is strongly depressed in MeCP2 KO mice. These alterations are presumably due to both decreased presynaptic γ-aminobutyric acid (GABA) release with reduced levels of the vesicular inhibitory transmitter transporter and reduced levels of postsynaptic GABAA-receptor subunits α2 and α4. Our data indicate that in the MeCP2 −/y mice specific synaptic molecules and signaling pathways are impaired in the brain stem during early postnatal development. These observations mandate the search for more refined diagnostic tools and may provide a rationale for the timing of future therapeutic interventions in Rett patients.

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