Search results for "Engram"

Visual Working Memory Requires Permissive and Instructive NO/cGMP Signaling at Presynapses in the Drosophila Central Brain.

2017

The gaseous second messenger nitric oxide (NO) has been shown to regulate memory formation by activating retrograde signaling cascades from post- to presynapse that involve cyclic guanosine monophosphate (cGMP) production to induce synaptic plasticity and transcriptional changes. In this study, we analyzed the role of NO in the formation of a visual working memory that lasts only a few seconds. This memory is encoded in a subset of ring neurons that form the ellipsoid body in the Drosophila brain. Using genetic and pharmacological manipulations, we show that NO signaling is required for cGMP-mediated CREB activation, leading to the expression of competence factors like the synaptic homer pr…

Mechanisms Underlying Memory Consolidation by Adult-Born Neurons During Sleep

2020

The mammalian hippocampus generates new neurons that incorporate into existing neuronal networks throughout the lifespan, which bestows a unique form of cellular plasticity to the memory system. Recently, we found that hippocampal adult-born neurons (ABNs) that were active during learning reactivate during subsequent rapid eye movement (REM) sleep and provided causal evidence that ABN activity during REM sleep is necessary for memory consolidation. Here, we describe the potential underlying mechanisms by highlighting distinct characteristics of ABNs including decoupled firing from local oscillations and ability to undergo profound synaptic remodeling in response to experience. We further di…

Hippocampal theta phase-contingent memory retrieval in delay and trace eyeblink conditioning

2017

Hippocampal theta oscillations (3-12Hz) play a prominent role in learning. It has been suggested that encoding and retrieval of memories are supported by different phases of the theta cycle. Our previous study on trace eyeblink conditioning in rabbits suggests that the timing of the conditioned stimulus (CS) in relation to theta phase affects encoding but not retrieval of the memory trace. Here, we directly tested the effects of hippocampal theta phase on memory retrieval in two experiments conducted on adult female New Zealand White rabbits. In Experiment 1, animals were trained in trace eyeblink conditioning followed by extinction, and memory retrieval was tested by presenting the CS at t…

Mismatch negativity (MMN) as a tool for investigating auditory discrimination and sensory memory in infants and children

2000

For decades behavioral methods, such as the head-turning or sucking paradigms, have been the primary methods to investigate auditory discrimination, learning and the function of sensory memory in infancy and early childhood. During recent years, however, a new method for investigating these issues in children has emerged. This method makes use of the mismatch negativity (MMN), the brain's automatic change-detection response, which has been used intensively in both basic and clinical studies in adults for twenty years. This review demonstrates that, unlike many other components of event-related potentials, the MMN is developmentally quite stable and can be obtained even from pre-term infants…

Forgetting at Short Term: When do Event-Based Interference and Temporal Factors Have an Effect?

2013

International audience; Memory tasks combining storage and distracting tasks performed at either encoding or retrieval have provided divergent results pointing towards accounts of forgetting in terms of either temporal decay or event-based interference respectively. The aim of this study was to shed light on the possible sources of such a divergence that could rely on methodological aspects or deeper differences in the memory traces elicited by the different paradigms used. Methodological issues were explored in a first series of experiments by introducing at retrieval computer-paced distracting tasks that involved articulatory suppression, attentional demand, or both. A second series of ex…

2016

Current research demonstrates increased learning rates in differencial learning (DL) compared to repetitive training. To date, little is known on the underlying neurophysiological processes in DL that contribute to superior performance over repetitive practice. In the present study, we measured electroencephalographic (EEG) brain activation patterns after DL and repetitive badminton serve training. Twenty-four semi-professional badminton players performed badminton serves in a DL and repetitive training schedule in a within-subjects design. EEG activity was recorded from nineteen electrodes according to the 10-20 system before and immediately after each 20-minute exercise. Increased theta a…

Phase-locked hippocampal theta-band responses are related to discriminative eyeblink conditioned responding

2013

Hippocampal electrophysiological oscillatory activity is undoubtedly related to learning and memory. The relative power of spontaneously occurring hippocampal theta (∼4-8 Hz) oscillations predicts how fast and how well an animal will learn: more theta predicts faster acquisition of the conditioned response in eyeblink conditioning in both rats and rabbits. Here, our aim was to study how hippocampal theta-band responses to conditioned stimuli elicited during very-long delay discrimination eyeblink conditioning relate to the accompanying conditioned behavior. We trained adult male New Zealand White rabbits using 1500-ms auditory stimuli as conditioned stimuli and a 100-ms airpuff as an uncond…

The use of the Emotional-Object Recognition as an assay to assess learning and memory associated to an aversive stimulus in rodents

2016

Abstract Background Emotionally salient experiences induce the formation of explicit memory traces, besides eliciting automatic or implicit emotional memory in rodents. This study aims at investigating the implementation of a novel task for studying the formation of limbic memory engrams as a result of the acquisition- and retrieval- of fear-conditioning – biased declarative memory traces, measured by animal discrimination of an “emotional-object”. Moreover, by using this new method we investigated the potential interactions between stimulation of cannabinoid transmission and integration of emotional information and cognitive functioning. New method The Emotional-Object Recognition task is …

Hippocampal evoked potentials to pitch deviances in an auditory oddball situation in the rabbit: no human mismatch-like dependence on standard stimul…

1995

Hippocampal auditory evoked potentials (AEP) were recorded in 10 rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, deviant tones were presented without intervening standard tones (deviant-alone situation). All AEP deflections observed in the oddball situation were found also in the deviant-alone situation. Thus, it appeared that none of the AEP deflections to deviant tones in the oddball situation was specific to a memory trace of preceding standard tones. This observation was in contradiction to such a specificity of the mismatch negativity (MMN) found in humans. Instead, a connection to a neuronal orienting reaction interpr…

L’anfiteatro romano dell’Urbe panormita tra paradigmi congetturali e possibili palingenesi

2022

Come il sottotitolo del libro di Giuseppe Ferrarella (Persistenza delle forme nell'architettura della città) eloquentemente dimostra, l’indagine compiuta svela una precisa prospettiva epistemica che si focalizza su una singola parte della città, il quartiere della Loggia, il cui disvelamento di senso va a modificare il complesso del sapere del “tutto”. Una conoscenza basata principalmente sul processo cognitivo di natura abduttiva o ipotesi di retroduzione, trattandosi di una inferenza del terzo tipo. Un procedimento logico, quindi, analogo alla deduzione e all’induzione, ma che cerca di spiegare i fatti osservati inferendo la causa dall’effetto, aggiungendovi sempre dell’altro, divenendo a…