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At least 55 records · Page 3Linked to original sources
PubMed2003

Frontal lesions do not alter the differential extinction of taste aversion conditioning in rats, when using two methods of sucrose delivery.

The frontal cortex is involved in the planning of behavioural responses and in the processing of their outcomes. Thus it contributes to several learning mechanisms, including those of conditioned taste aversion (CTA). A solution of sucrose drunk freely by a rat from a drinking tube-self-drinking protocol (SD)-was used as a conditioned stimulus in CTA. The intake of this solution was followed by gastric malaise. It produced an aversion to sucrose that withstood extinction over a week of repetitive tests. But, when the sucrose was perfused intra-orally (IO), i.e. not depending on any specific action by the rat, the extinction of aversion was much faster. Several factors may explain this differential extinction including the contribution of contextual factors linked to the achievement of an action and/or the enhancement of the attention towards the outcome of the action (the taste). The processing of such factors is usually believed to require the prefrontal cortex or the cingulate cortex (CgC). In our first experiment, the frontal cortex was totally transected. In the second experiment, the CgC was removed by aspiration. None of these lesions elicited any change in CTA, either in IO or in SD conditions, meaning that the differential extinction remained. The surprising absence of a frontal lesion effect was thought to indicate the low attentional demand required in both CTA protocols.

Animals↗
PubMed2001

Enhancement of conflict processing activity in human brain under task relevant condition.

To investigate the working mechanism of the conflict processing system, pairs of colored numbers were sequentially presented on a screen to subjects. They were asked to determine if the magnitude or the color of the two numbers was identical. Event-related potentials (ERPs) were recorded at the same time. A negative potential peaking at 270 ms (N270) after the onset of the second number (S2) was elicited when S2 conflicted with the first number (S1) in task-relevant and (or) irrelevant attribute conflicts. The mean amplitude of the N270 was more negative in task relevant conflict than in irrelevant conflict. Therefore, the conflict processing activity can be initiated independently of the task, but is enhanced in task relevant conflict.

Adult↗
PubMed1999

Effects of the presentation of false heart-rate feedback on the performance of two common heartbeat-detection tasks.

Research has indicated that performance on heartbeat counting tasks may be influenced by beliefs about heart rate. Sixty male subjects were administered the Schandry heartbeat counting task after viewing fast, slow, or no heart rate feedback. Subjects were also administered the Whitehead signal-detection type task. Results indicated that subjects who received fast or no heartbeat feedback performed better on the Schandry task than subjects who received slow feedback. Feedback presentation did not affect performance on the Whitehead task. These results suggest that the Schandry task is influenced by external variables (expectations, beliefs) beyond pure awareness of "discrete" visceral sensations and, thus, may not be as powerful a method for determining awareness of individual heartbeats as some other paradigms.

Adult↗
PubMed2004

Unconscious learning. Conditioning to subliminal visual stimuli.

The role of consciousness in Pavlovian conditioning was examined in two experiments in which visually masked neutral words were used as the conditioned stimuli (CS) and an electric shock as the unconditioned stimulus (US). The inter-stimulus interval (ISI) was established individually. A detection threshold was used in Experiment 1 and an identification threshold in Experiment 2. The primary dependent variable was the skin conductance response (SCR). Results showed that the conditioned response (CR) was acquired by 58% of participants who perceived stimuli above the identification threshold, 50% of participants who perceived stimuli below the detection threshold, and 11% of participants who perceived stimuli below the identification threshold, but above the detection threshold. These results suggest that consciousness of the CS-US contingency is not a necessary condition for acquiring a CR of the autonomous nervous system (ANS).

Adolescent↗
PubMed2005

A mechanism for error detection in speeded response time tasks.

The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors by identifying states of the system associated with negative value. The mechanism is formalized in a computational model based on a recent theoretical framework for understanding error processing in humans (C. B. Holroyd & M. G. H. Coles, 2002). The model is used to simulate behavioral and event-related brain potential data in a speeded response time task, and the results of the simulation are compared with empirical data.

Attention↗
PubMed2003

Configurational and nonconfigurational interactions between odorants in binary mixtures.

Studies on odor mixture perception suggest that although odor components can often be identified in mixtures, mixtures can also give rise to novel perceptual qualities that are not present in the components. Using an olfactory habituation task, the authors evaluated how the perceptual similarity between components in a mixture affects the perceptual quality of the mixture itself. Rats perceived binary mixtures composed of similar components as different from their 2 components, whereas binary mixtures composed of dissimilar components were perceived as very similar to their components. Results show that for both types of mixtures, pretraining to Component A reduces subsequent learning about Component B in rats trained in the presence of A.

Animals↗
PubMed2006

Awareness of faces is modulated by their emotional meaning.

A central question in perception is how stimuli are selected for access to awareness. This study investigated the impact of emotional meaning on detection of faces using the attention blink paradigm. Experiment 1 showed that fearful faces were detected more frequently than neutral faces, and Experiment 2 revealed preferential detection of fearful faces compared with happy faces. To rule out image artifacts as a cause for these results, Experiment 3 manipulated the emotional meaning of neutral faces through fear conditioning and showed a selective increase in detection of conditioned faces. These results extend previous reports of preferential detection of emotional words or schematic objects and suggest that fear conditioning can modulate detection of formerly neutral stimuli.

Adult↗