Predictive coding reflects the ability of the human brain to extract environmental patterns in order to reformulate previous expectations. The present report analyzes through the late N1 auditory component and the pos...
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Predictive coding reflects the ability of the human brain to extract environmental patterns in order to reformulate previous expectations. The present report analyzes through the late N1 auditory component and the postimperative negative variation (PINV) the updating of predictions regarding the characteristics of a new trial, depending on the previous trial history, complexity, and type of trial (standard or deviant). Data were obtained from 31 healthy subjects recorded in a previous study based on two paradigms composed of stimulus sequences of decreasing or increasing frequencies intermingled with the sporadic appearance of unexpected tone endings. Our results showed a higher amplitude for the most complex condition and deviant trials for both the late N1 and PINV components. Additionally, the N1 and PINV presented a different amplitude response to the standard and deviant trials as a function of previous trial history, suggesting a continuous updating of trial categorization. The results suggest that the late N1 and PINV components are involved in the generation of an internal model about the rules of external auditory stimulation. NEW & NOTEWORTHY The present study showed a higher amplitude for the late N1 and the PINV with reference to both the prediction performed in auditory paradigms of higher abstraction and the unexpected breaking of the extracted rules. Additionally, both components were modulated depending on the local probability, which would suggest that they are continuously being updated by the previous stimulus history.
A longstanding held assumption is that left-handers present a distinct cerebral language organization than right-handers. However, only few studies have considered this difference in studying the impact of intra and i...
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A longstanding held assumption is that left-handers present a distinct cerebral language organization than right-handers. However, only few studies have considered this difference in studying the impact of intra and interindivual factors on language hemispheric dynamic. The goal of the present thesis is to gain insight into the language hemispheric dynamic in right-and left-handers for two fundamental language components which are phonological and semantic processing of words. At that end, a phonological task that asked for a grapho-phonemic matching judgment and a semantic task that called for a category judgment were used through a behavioral divided visual field paradigm (Walter, Beauregard, & Joanette, 2002; Walter, Cliche, Joubert, Beauregard, & Joanette, 2001). These two tasks have been chosen because they both present an easy and a difficult level of processing, which have been manipulated according to graphophonemic transparency (phonological task) or semantic prototypicality (semantic task). After contextualizing that research into a larger perspective (chapter 1), a literature review about left-hander's language cerebral organization deployed the matter of that thesis (chapter 2). After that, empirical studies will explore gender effect as weIl as complexity processing effect in right and left-handers (chapter 3 and 4). Results suggest a differentia effect of the gender according to handedness and of the complexity processing whether phonology or semantic is involved. First, gender modulates the hemispheric dynamic solely in left-handers with men demonstrated better equilibrium between left and right-hemisphere performance than women. Second, results suggest that an increase of complexity processing solicits both hemispheres collaboration during semantic but not phonological processing of words whatever the handedness or the gender. Rather, an increase in phonological complexity seems to engage essentially the left-hemisphere and to be held by an intrahemi
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