Intensity of the Unconditional Stimulus as a Factor in Conditioning Out of Awareness

1963 ◽  
Vol 25 (2) ◽  
pp. 124-132 ◽  
Author(s):  
WILLIAM F. WIELAND ◽  
MARVIN STEIN ◽  
CHARLES L. HAMILTON
Keyword(s):  
Unconditional Stimulus

Synaptic plasticity of the interpositorubral pathway functionally related to forelimb flexion movements

1996 ◽  
Vol 75 (6) ◽  
pp. 2542-2561 ◽  
Author(s):  
M. Pananceau ◽  
L. Rispal-Padel ◽  
E. M. Meftah
Keyword(s):  
Synaptic Plasticity ◽  
Synaptic Transmission ◽  
Response Rate ◽  
Unconditional Stimulus ◽  
Red Nucleus ◽  
Field Potential ◽  
Angular Deviation ◽  
Interpositus Nucleus ◽  
Motor Responses ◽  
Adult Cats

1. Some connections from the afferents to the magnocellular red nucleus (RNm), like the corticorubral synapses, have plastic properties that are thought to contribute to long-term changes such as functional readaptation, motor learning, and the establishment of conditioned responses. Because previous studies have focused on corticorubral synaptic reorganization after these events, we attempted to investigate cerebellorubral connections in intact adult cats during associative conditioning by pairing electrical stimulation of interpositus nucleus [the conditional stimulus (CS)] with electrical simulation of the forelimb [the unconditional stimulus (UCS)]. A large increase in the amplitude of the forelimb flexion (conditioned response) induced by the CS was observed after several days of paired CS-UCS presentations. 2. For this purpose, both behavioral and electrophysiological methods were used to correlate synaptic plasticity with changes in the motor responses. The somatotopically organized sensorimotor network functionally related to the control of the elbow joint movements was studied in awake adult cats. This circuit was defined on the basis of sites at which elbow flexions could be evoked both as a CS and a UCS. The CS was applied in the cerebellar interpositus nucleus (IN) site and the UCS was given to the skin on the dorsum of the distal part of the forepaw. Daily classical conditioning consisted of repetitive pairings of CS and UCS with an interstimulus interval (ISI) of 100 ms. 3. The transmission efficacy resulting from the conditioning was tested in various targets of the cerebellar efferent pathway, including the RNm. Electrophysiological responses evoked in these relay structures by the CS and the forelimb angular deviations were simultaneously recorded throughout each daily conditioning session. The surface areas of the rubral responses to CS and the percentage response rate, the angular deviation (amplitude), and the latency of the motor responses were systematically measured throughout the conditioning procedure. Test sessions were also performed before and after each period of conditioning. Quantification and statistical analysis were carried out to determine whether changes observed in interpositorubral synaptic transmission and in the motor responses evoked by the CS were correlated. 4. Daily repetition of paired CS and UCS according to a predefined and fixed temporal schedule led to an increase in the response rate and amplitude of the forelimb flexions. A procedure with repeated presentation of CS preceded by UCS was used to produce extinction of the enhanced motor responses. The associative nature of these changes was confirmed by the fact that the CS given alone for 11 days in a control condition failed to produce any modification of the motor response. 5. The changes in the flexion movements were accompanied by a nearly parallel increase of the amplitude of the “postsynaptic field potentials” evoked in the RNm by the CS (IN stimulation). Changes in the transmission efficacy of the interpositorubral synapses stayed stable even after several days of interruption and remained constant up the extinction period. Changes affecting both the motor and the central responses were significantly correlated, suggesting that modifications in the interpositorubral transmission efficacy might be one of the plastic correlates of forelimb flexion conditioning. 6. Examination of the neuronal excitability within either the IN or the RNm or in the spinal cord failed to show any evidence of facilitation suggesting that the increases in the postsynaptic rubral field potential were attributable to a plasticity of the interpositorubral connections. The long-lasting duration of the increase of cerebellorubral synaptic transmission suggests that structural changes were induced by conditioning in the intact animal. (ABSTRACT TRUNCATED)

Learned Irrelevance and Retrospective Correlation Learning

2003 ◽  
Vol 56 (1b) ◽  
pp. 90-101 ◽  
Author(s):  
A. G. Baker ◽  
Robin A. Murphy ◽  
Rick Mehta
Keyword(s):  
Conditioned Stimulus ◽  
Pavlovian Conditioning ◽  
Learning Process ◽  
Interference Effect ◽  
Unconditional Stimulus ◽  
Contingency Learning ◽  
Correlation Learning ◽  
Learned Irrelevance

In 1973 Mackintosh reported an interference effect that he called learned irrelevance in which exposure to uncorrelated (CS/US) presentation of the unconditional stimulus (US) and the conditioned stimulus (CS) interfered with future Pavlovian conditioning. It has been argued that there is no specific interference effect in learned irrelevance; rather the interference is the sum of independent CS and US exposure effects (CS + US). We review previous research on this question and report two new experiments. We conclude that learned irrelevance is a consequence of a contingency learning and a specific learned irrelevance mechanism. Moreover even the “independent exposure controls”, used in previous experiments to support the CS and US exposure account, provide support for the correlation learning process.

scholarly journals Acquisition and maintenance of disgust reactions in an OCD analogue sample: Efficiency of extinction strategies through a counter-conditioning procedure

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254592
Author(s):  
Caroline Novara ◽  
Cindy Lebrun ◽  
Alexandra Macgregor ◽  
Bruno Vivet ◽  
Pierre Thérouanne ◽  
...  
Keyword(s):  
Anxiety Disorder ◽  
Conditioned Stimulus ◽  
Associative Learning ◽  
Unconditional Stimulus ◽  
Emotional Responses ◽  
Learning Task ◽  
Conditioning Procedure ◽  
Obsessive Compulsive ◽  
Compulsive Disorder ◽  
Highly Correlated

Background Obsessive-compulsive disorder (OCD) has long been considered as an anxiety disorder, disgust is the dominant emotion in contamination-based OCD. However, disgust seems resistant to exposure with response prevention partly due to the fact that disgust is acquired through evaluative conditioning. Aims The present research investigates a counter-conditioning intervention in treating disgust-related emotional responses in two groups of individuals with high (High contamination concerns, HCC, n = 24) and low (Low contamination concerns LCC, n = 23) contamination concerns. Methods The two groups completed a differential associative learning task in which neutral images were followed by disgusting images (conditioned stimulus; CS+), or not (CS-). Following this acquisition phase, there was a counter-conditioning procedure in which CS+ was followed by a very pleasant unconditional stimulus while CS- remained unreinforced. Results Following counter-conditioning, both groups reported significant reduction in their expectancy of US occurrence and reported less disgust with CS+. For both expectancy and disgust, reduction was lower in the HCC group than in the LCC group. Disgust sensitivity was highly correlated with both acquisition and maintenance of the response acquired, while US expectation was predicted by anxiety. Conclusion Counter-conditioning procedure reduces both expectations and conditioned disgust.

scholarly journals The Role of National Energy Policies and Life Cycle Emissions of PV Systems in Reducing Global Net Emissions of Greenhouse Gases

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 961
Author(s):  
Gabriel Constantino de Lima ◽  
Andre Luiz Lopes Toledo ◽  
Leonidas Bourikas
Keyword(s):  
Life Cycle ◽  
Electricity Generation ◽  
Unconditional Stimulus ◽  
Average Energy ◽  
Carbon Intensity ◽  
Photovoltaic Systems ◽  
Low Carbon ◽  
Operational Conditions ◽  
Pv Systems ◽  
Carbon Offset

The energy sector and electricity generation in particular, is responsible for a great share of the global greenhouse gas (GHG) emissions. World electricity generation is still largely based on the burning of fossil fuels. However, Brazil has already a very low electricity carbon intensity due to the country’s large hydropower capacity. In countries with low grid carbon intensities such as Brazil, the investment in photovoltaic solar systems (PVSS) even if it is cost-effective, might become challenging as any new generation competes essentially against other renewable generation and the carbon offset is not a key driver for investment anymore. This study builds further upon that case to examine if national renewable energy incentives could actually lead to an increase of global net carbon emissions from the installation of PVSS in countries with a low grid carbon intensity. The study presents a life cycle analysis (LCA) of ten photovoltaic systems representative of the different operational conditions in regions across Brazil. It was found that the average energy payback time of the studied PV plants is between 3 and 5 years of operation. This result shows the feasibility and viability of such investments in the Brazilian context. When the LCA was integrated into the analysis though, the results showed that the “local” direct emissions avoidance from two out of ten studied PV plants would not manage to offset their “global” life cycle emissions due to the 2020 projected Brazilian grid emission factor which is already low. It is important to recognize that public policies of unrestricted, unconditional stimulus to photovoltaic systems investment might not help towards reducing global net emissions when the PV systems are installed at countries with a low carbon emission electric matrix. That is also something to consider for other countries as the carbon intensity of their grids will start reducing at levels similar to Brazil’s. It is likely that in the near future, the real net carbon offset achieved by PV systems at the global level will be largely defined by the manufacture procedures and the production’s carbon intensity at the country of origin of the PV panels.

scholarly journals Purkinje cell activity during classical conditioning with different conditional stimuli explains central tenet of Rescorla–Wagner model

2015 ◽  
Vol 112 (45) ◽  
pp. 14060-14065 ◽  
Author(s):  
Anders Rasmussen ◽  
Riccardo Zucca ◽  
Fredrik Johansson ◽  
Dan-Anders Jirenhed ◽  
Germund Hesslow
Keyword(s):  
Purkinje Cell ◽  
Purkinje Cells ◽  
Compound Stimulus ◽  
Eyeblink Conditioning ◽  
Unconditional Stimulus ◽  
Cell Activity ◽  
Neural Mechanisms ◽  
Wagner Model ◽  
Central Tenet ◽  
Reinforcement Value

A central tenet of Rescorla and Wagner’s model of associative learning is that the reinforcement value of a paired trial diminishes as the associative strength between the presented stimuli increases. Despite its fundamental importance to behavioral sciences, the neural mechanisms underlying the model have not been fully explored. Here, we present findings that, taken together, can explain why a stronger association leads to a reduced reinforcement value, within the context of eyeblink conditioning. Specifically, we show that learned pause responses in Purkinje cells, which trigger adaptively timed conditioned eyeblinks, suppress the unconditional stimulus (US) signal in a graded manner. Furthermore, by examining how Purkinje cells respond to two distinct conditional stimuli and to a compound stimulus, we provide evidence that could potentially help explain the somewhat counterintuitive overexpectation phenomenon, which was derived from the Rescorla–Wagner model.

scholarly journals Effect of Intensity of Unconditional Stimulus on Reconsolidation of Contextual Fear Memory

2012 ◽  
Vol 16 (5) ◽  
pp. 293 ◽  
Author(s):  
Chuljung Kwak ◽  
Jun-Hyeok Choi ◽  
Joseph T. Bakes ◽  
Kyungmin Lee ◽  
Bong-Kiun Kaang
Keyword(s):  
Unconditional Stimulus ◽  
Fear Memory ◽  
Contextual Fear ◽  
Contextual Fear Memory

Perceptual Imprinting: Stimulus Preferences, Age Effects, and Genetic Canalization

Behaviour ◽  
1987 ◽  
Vol 102 (3-4) ◽  
pp. 239-263 ◽  
Author(s):  
Joseph K. Kovach
Keyword(s):  
Unconditional Stimulus ◽  
Genetic Selection ◽  
Age Effects ◽  
Coturnix Japonica ◽  
Stable Gene ◽  
Gene Effects ◽  
Stimulus Effects ◽  
Selection For ◽  
Early Developmental

AbstractThe separate and interactive influences of genetically variable unconditional stimulus preference, age effects, and genetic canalization were studied in relation to perceptual imprinting in Japanese quail chicks (C. coturnix japonica). The chicks were drawn from populations subjected to 21 generations of bidirectional genetic selection for unconditional approach preference between blue and red stimuli. They were tested for age and stimulus effects in perceptual learning from synergistic and conflicting exposures to the genetically preferred and genetically unpreferred colours. Unselected quail chicks were tested as genetic controls, and the qualitative influences of exposures to colours were controlled by comparable exposures to white and other preference-wise neutral stimuli. The results indicate robust and developmentally stable gene effects in the quail's unconditional colour choices, developmentally persistent but episodically variable learning from exposures to colours of genetically variable preference values, and systematic genotype-environment interactions. Discussion focuses on the canalizing role of genetically variable unconditional stimulus preferences in the early developmental of behaviour.

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