The time course of visual influences in letter recognition

This study builds on a specific characteristic of letters of the Roman alphabet—namely, that each letter name is associated with two visual formats, corresponding to their uppercase and lowercase versions. Participants had to read aloud the names of single letters, and event-related potentials (ERPs) for six pairs of visually dissimilar upper- and lowercase letters were recorded. Assuming that the end product of processing is the same for upper- and lowercase letters sharing the same vocal response, ERPs were compared backward, starting from the onset of articulatory responses, and the first significant divergence was observed 120 ms before response onset. Given that naming responses were produced at around 414 ms, on average, these results suggest that letter processing is influenced by visual information until 294 ms after stimulus onset. This therefore provides new empirical evidence regarding the time course and interactive nature of visual letter perception processes.     

Zinc transporter 3 is involved in learned fear and extinction, but not in innate fear

Synaptically released Zn2+ is a potential modulator of neurotransmission and synaptic plasticity in fear-conditioning pathways. Zinc transporter 3 (ZnT3) knock-out (KO) mice are well suited to test the role of zinc in learned fear, because ZnT3 is colocalized with synaptic zinc, responsible for its transport to synaptic vesicles, highly enriched in the amygdala-associated neural circuitry, and ZnT3 KO mice lack Zn2+ in synaptic vesicles. However, earlier work reported no deficiency in fear memory in ZnT3 KO mice, which is surprising based on the effects of Zn2+ on amygdala synaptic plasticity. We therefore reexamined ZnT3 KO mice in various tasks for learned and innate fear. The mutants were deficient in a weak fear-conditioning protocol using single tone-shock pairing but showed normal memory when a stronger, five-pairing protocol was used. ZnT3 KO mice were deficient in memory when a tone was presented as complex auditory information in a discontinuous fashion. Moreover, ZnT3 KO mice showed abnormality in trace fear conditioning and in fear extinction. By contrast, ZnT3 KO mice had normal anxiety. Thus, ZnT3 is involved in associative fear memory and extinction, but not in innate fear, consistent with the role of synaptic zinc in amygdala synaptic plasticity.     

Basolateral amygdala noradrenergic activity is involved in the acquisition of conditioned odor aversion in the rat

Conditioned odor aversion (COA) is the avoidance of an odorized-tasteless solution (the conditioned stimulus, CS), the ingestion of which precedes toxicosis. Previous works have shown that the basolateral nucleus of the amygdala (BLA) is involved in the acquisition, and more precisely, the control of the CS memory trace, of COA. Since catecholamine depletion of the amygdala induced a deficit in the potentiated version of COA, this study investigated the role of the adrenergic system in the BLA during COA. Male Wistar rats bilaterally implanted with cannulae aimed at the BLA were microinjected with the beta-adrenergic antagonist propranolol (1 microg/0.2 microl) during the acquisition (5 min before the CS presentation, pre-CS, or immediately after, post-CS) or during the retrieval test (5 min before test, pre-test). Results showed that pre-CS, but neither post-CS nor pre-test, infusions of propranolol impaired COA, suggesting that beta-adrenergic system activity in the BLA is involved in the acquisition but not the expression of COA. Moreover, the fact that pre-CS, but not post-CS, treatment disrupted COA suggests that beta-adrenergic system in the BLA is involved in the initiation but not the maintenance of the CS memory trace during COA acquisition.     

Searching for the Self: Early Phenomenological Accounts of Self-Consciousness from Lotze to Scheler

Abstract

Phenomenological accounts of self-consciousness are often said to combine two elements by means of a necessary connection: the primitive and irreducible subjective character of experiences and the idealist transcendental constitution of consciousness. In what follows I argue that this connection is not necessary in order for an account of self-consciousness to be phenomenological, as shown by early phenomenological accounts of self-consciousness – particularly in Munich phenomenology. First of all, I show that the account of self-consciousness defended by these phenomenologists was not influenced as much by Husserl as by two important figures in the prehistory of phenomenology: their teacher Theodor Lipps, and – indirectly, through Lipps’ influence – Hermann Lotze. Second, I show that their account of self-consciousness takes the metaphysical realism underlying Lotze’s and Lipps’ views on the distinction between feeling and sensations seriously. I argue that this distinction played a central role in the development of many early phenomenological accounts of self-consciousness.     

Quelques remarques sur les ‘Tableaux de Beth’

Sans résumé     

How parallel is visual processing in the ventral pathway?

Visual object perception is usually studied by presenting one object at a time at the fovea. However, the world around us is composed of multiple objects. The way our visual system deals with this complexity has remained controversial in the literature. Some models claim that the ventral pathway, a set of visual cortical areas responsible for object recognition, can process only one or very few objects at a time without ambiguity. Other models argue in favor of a massively parallel processing of objects in a scene. Recent experiments in monkeys have provided important data about this issue. The ventral pathway seems to be able to perform complex analyses on several objects simultaneously, but only during a short time period. Subsequently only one or very few objects are explicitly selected and consciously perceived. Here, we survey the implications of these new findings for our understanding of object processing.