Attentional functions of cortical cholinergic inputs: what does it mean for learning and memory?

The hypothesis that cortical cholinergic inputs mediate attentional functions and capacities has been extensively substantiated by experiments assessing the attentional effects of specific cholinotoxic lesions of cortical cholinergic inputs, attentional performance-associated cortical acetylcholine release, and the effects of pharmacological manipulations of the excitability of basal forebrain corticopetal cholinergic projections on attentional performance. At the same time, numerous animal experiments have suggested that the integrity of cortical cholinergic inputs is not necessary for learning and memory, and a dissociation between the role of the cortical cholinergic input system in attentional functions and in learning and memory has been proposed. We speculate that this dissociation is due, at least in part, to the use of standard animal behavioral tests for the assessment of learning and memory which do not sufficiently tax defined attentional functions. Attentional processes and the allocation of attentional capacities would be expected to influence the efficacy of the acquisition and recall of declarative information and therefore, persistent abnormalities in the regulation of the cortical cholinergic input system may yield escalating impairments in learning and memory. Furthermore, the cognitive effects of loss of cortical cholinergic inputs are augmented by the disruption of the top-down regulation of attentional functions that normally acts to optimize information processing in posterior cortical areas. Because cortical cholinergic inputs play an integral role in the mediation of attentional processing, the activity of cortical cholinergic inputs is hypothesized to also determine the efficacy of learning and memory.     

Dopaminergic modulation of the persistence of one-trial hippocampus-dependent memory

The persistence of new memory traces in the hippocampus, encoded following appropriate activation of glutamatergic receptors and the induction of synaptic plasticity, can be influenced by heterosynaptic activation of neuromodulatory brain systems. We therefore investigated the effects of a hippocampus-specific blockade of dopamine D1/D5 receptors on the persistence of spatial memory encoded in one trial using a delayed matching-to-place (DMP) task in a watermaze in which rats learn a new escape location each day. A within-subjects design was used such that both short (20 min) and long (6 h) retention intervals, and both drug (SCH23390, a D1/D5 receptor antagonist) and vehicle (aCSF) infusions were tested on different days in the same animals. Bilateral intrahippocampal infusion of SCH23390 (5 microg in 1 microL per side) prior to trial 1 (encoding) caused a differential impairment as a function of memory delay-with no effect during trial 2 (memory retrieval) after a 20-min interval, but a block of memory at 6 h. Further experiments revealed that infusion of SCH23390 immediately after trial 1 had no effect on retention 6 h later, and the poor memory seen at long retention intervals when the drug was present at encoding was not due to a state-dependent failure of retrieval. These results suggest that activation of D1/D5 receptors during memory encoding is necessary for the formation of a persistent memory trace in the hippocampus. The complementary effects of D1/D5 receptor blockade on the persistence of LTP and the duration of memory are consistent with the idea that changes in synaptic strength underlie memory.     

Automaticity and voluntary control of phase correction following event onset shifts in sensorimotor synchronization

Seven experiments show that an event onset shift (EOS) in an auditory sequence causes an involuntary phase correction response (PCR) in synchronized finger tapping. This PCR is (a) equally large in inphase and antiphase tapping; (b) reduced but still present when the EOS occurs in either of two interleaved (target-distractor) sequences; (c) unaffected by increased pitch separation between these sequences; (d) asymptotic in magnitude as EOS magnitude increases, unlike the intentional PCR to expected phase shifts; and (e) enhanced when the EOS precedes the onset of tapping, because of phase resetting. Thus, phase correction is revealed to be partially automatic and partially under voluntary control, and to be based mainly on temporal information derived from simple onset detection.     

Albert le Grand: De ce qui vient avant la logique

Le premier tractatus du commentaire d'Albert le Grand à l'Isagoge de Porphyre consiste en une manière de proème ou d'introduction à l'ensemble de la logique. Comme la plupart des textes d'Albert le Grand, ce traité est d'une très grande richesse, qu'atténuent toutefois son manque d'ordre et son obscurité d'expression. Étant donné que les aspects fondamentaux de la logique y sont touchés—son statut scientifique et philosophique, son utilité, son sujet, sa division, sa relation aux sciences du langage, etc.—, ce petit ouvrage est du plus haut intérêt pour quiconque cherche à mieux comprendre la logique et la philosophie de la logique du XIII^e siècle. L'auteur présente ici une traduction annotée et expliquée de ce texte difficile, faite d'après la version provisoire de la nouvelle édition de Cologne. Le relevé des sources principales de l'ouvrage révèle, sur un fond aristotélicien permanent, une forte influence des traités logiques arabes nouvellement arrivés en Occident.

The first tractatus of Albert the Great's commentary on Porphyry's Isagoge consists of a kind of proem or introduction to the whole of logic. As most of Albert the Great's texts, this tract is of great richness, though it lacks order and is sometimes obscure. Since the fundamental themes of logic are addressed therein—its scientific and philosophical status, its utility, its subject, its division, its relation to the linguistic arts, etc.—, this small work is of high interest for anyone trying to better understand thirteenth-century logic and philosophy of logic. The author presents a translation of this difficult text, made after a preliminary version of the new critical edition and enriched with an introduction and explanatory notes. The survey of the main sources of the tract reveals, apart from a permanent artistotelian background, the strong influence of the Arabic logical treatises which were then coming in the Western world.     

Subjective Well-Being and Policy

This paper analyses whether the aggregation of individual happiness scores to a National Happiness Index can still be trusted once governments have proclaimed their main objective to be the pursuit—or even maximization—of this National Happiness Index. The answer to this investigation is clear-cut: as soon as the National Happiness Index has become a policy goal, it can no longer be trusted to reflect people’s true happiness. Rather, the Index will be systematically distorted due to the incentive for citizens to answer strategically and the incentive for government to manipulate the Index in its favour. Such a distortion would arise even if the measurement of subjective well-being correctly reflected actual happiness before the intervention of government. Governments in a democracy should establish the conditions enabling individuals to become happy. The valuable and important results of happiness research should be introduced into the political process. Each person should be free to pursue happiness according to his or her preferences. This process is supported by obedience to the rule of law, human rights and free media, as well as by extended political participation rights, decentralized public decision-making, an open and effective education system fostering upward mobility and the possibility to find suitable employment.     

Simultaneous Event-Based and Emergent Timing: Synchronization,Continuation, and Phase Correction

It has been claimed that rhythmic tapping and circle drawing represent fundamentally different timing processes (event-based and emergent, respectively) and also that circle drawing is difficult to synchronize with a metronome and exhibits little phase correction. In the present study, musically trained participants tapped with their left hands, drew circles with their right (dominant) hands, and also performed both tasks simultaneously. In Experiment 1, they synchronized with a metronome and then continued on their own, whereas in Experiment 2, they synchronized with a metronome containing phase perturbations. Circle drawing generally exhibited reliable synchronization, although with greater variability than tapping, and also showed a clear phase-correction response that evolved gradually during the cycle immediately following a perturbation. When carried out simultaneously in synchrony, with or without a metronome, the two tasks affected each other in some ways but retained their distinctive timing characteristics. This shows that event-based and emergent timing can coexist in a dual-task situation. Furthermore, the authors argue that the two timing modes usually coexist in each individual task, although one mode is often dominant.     

Comparison of Methods for Collecting and Modeling Dissimilarity Data: Applications to Complex Sound Stimuli

Sorting procedures are frequently adopted as an alternative to dissimilarity ratings to measure the dissimilarity of large sets of stimuli in a comparatively short time. However, systematic empirical research on the consequences of this experiment-design choice is lacking. We carried out a behavioral experiment to assess the extent to which sorting procedures compare to dissimilarity ratings in terms of efficiency, reliability, and accuracy, and the extent to which data from different data-collection methods are redundant and are better fit by different distance models. Participants estimated the dissimilarity of either semantically charged environmental sounds or semantically neutral synthetic sounds. We considered free and hierarchical sorting and derived indications concerning the properties of constrained and truncated hierarchical sorting methods from hierarchical sorting data. Results show that the higher efficiency of sorting methods comes at a considerable cost in terms of data reliability and accuracy. This loss appears to be minimized with truncated hierarchical sorting methods that start from a relatively low number of groups of stimuli. Finally, variations in data-collection method differentially affect the fit of various distance models at the group-average and individual levels. On the basis of these results, we suggest adopting sorting as an alternative to dissimilarity-rating methods only when strictly necessary. We also suggest analyzing the raw behavioral dissimilarities, and avoiding modeling them with one single distance model.     

Unconscious and conscious priming by forms and their parts

Using metacontrast masking techniques, in two experiments we compare unconscious and conscious response priming by targets consisting of either whole forms or else their parts. In Experiment 1 we investigate the contribution of whole forms and their figural primitives, viz., edges and corners, to the unconscious priming effect. As expected, choice RTs were fast when the invisible target and visible mask shape pairings were congruent and slower when they were incongruent. This trend, while strongest for whole-targets, also held for the target primes composed only of corners but did not hold for target primes composed only of sides. Experiment 2 showed, replicating the results of Experiment 1, that while invisible corner targets produced weaker priming effects than invisible whole targets, paradoxically visible corner target produced stronger priming effects than visible whole targets. Taken together the results of the two experiments indicate (a) that unconscious target representations and, thus, unconscious priming effects are strongest when the target is a complete rather than a partial configuration, (b) that conjunctions of line or edge orientations forming corners produce stronger unconscious target representations and priming effects than do unconscious target representations formed from nonconjoined edge or line primitives, (c) that metacontrast masking of form occurs at or beyond levels of visual processing at which feature integration of visual form primitives occurs, and (d) that, when consciously perceived, partial forms can act as stronger primes than whole forms.     

Holistic face encoding is modulated by perceived face race: Evidence from perceptual adaptation

Human expertise at processing faces relies on how facial features are encoded: as a whole template rather than as a sum of independent features. This holistic encoding is less prominent for other-race faces, possibly accounting for the difficulty one encounters in recognizing these faces (the ‘other-race effect’). Here, we tested the hypothesis that the magnitude of holistic face encoding can be modulated by racial categorization of the face. Caucasian participants performed a face-composite task with ‘racially-ambiguous’ face-stimuli (cross-race morphed faces, equally categorized as Asian or Caucasian faces in an independent task). The perceived race of the ambiguous faces was manipulated using adaptation. Experiment 1 showed that identical morphed face-stimuli were processed more holistically when perceived as ‘same-race’ than as ‘other-race’, i.e., following adaptation to ‘other-race’ versus ‘same-race’, respectively. Experiment 2 ascertained that the determining factor in the observed holistic processing modulation was the race of the racially-ambiguous face as perceived, rather than expected, by the participants, which supports the idea that the holistic processing of the face-stimuli was modulated by their race-categorization at the perceptual level.