About this Research Topic
Priming refers to modifications in the way a stimulus is processed depending on the stimuli previously encountered (primes). In its simplest form - repetition priming - the processing of a target stimulus will be faster, and more reliable, if the same stimulus has been previously encountered. In associative priming, instead, the processing of a target stimulus is made more effective by stimuli which are different from, but related to, the target. For instance, in lexical decision tasks, subjects response times (and accuracy) in identifying a target stimulus as a 'word' highly rely on its semantic relation to previously presented material (one to several primes).
Priming relates, thus, to a form of memory. It exhibits, however, several remarkable features which have led to the suggestion that priming is sub-served by a system which can operate in a fashion relatively independent from the system(s) which support explicit memory.
Although the majority of studies on priming effects have been carried out in humans by using verbal materials, priming is also observed with non-verbal materials in human and non-human primates. This allows one to make contact between human behavior and the neural activity observed in priming-like experiments in animals. Importantly priming-like studies in animals open a window on putative physiological correlates of priming at the single-cell and local network levels.
Electro-physiological studies in animals have revealed several neuronal correlates of memory functions. The most renowned one is the so-called persistent activity, that is enhanced/reduced stimulus-selective spiking rates exhibited by neuronal sub-populations during the delay period in delayed-response tasks. Persistent activity can be related to the preceding cue stimulus, to the impending target stimulus when preceded by a related stimulus or to both. Within the same experimental paradigms, another major class of 'memory' signals is commonly observed, which consist of enhanced/suppressed neuronal responses to stimulus presentation. It has been recently suggested that repetition suppression would be a neuronal correlate of perceptual priming. Intriguingly, the different memory signals are observed in the same regions and, very often, are co-exhibited at the single-cell level. For instance, a cell showing persistent activity is also likely to exhibit enhancement/suppression of the response upon stimulus presentation.
This research topic aims to present state-of-the-art understanding of priming effects, their neuro-physiological correlates and their relationships with other forms of memory (e.g., short-term memory, long-term associative memory). It welcomes behavioral studies (e.g., response times, accuracy) and physiological studies (e.g, ERP, fMRI, single-cell recordings) in both humans and animals, as well as computational studies. A particular emphasis will be placed on these latter to the extent to which they provide minimal theoretical frameworks which link priming effects, patterns of neuronal activity and synaptic plasticity at the mechanistic level.
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