Episodic Memory in Schizophrenia

Episodic memory impairments in individuals with schizophrenia have been well documented in the literature. However, despite the abundance of findings, constituent cognitive, neural, behavioral, and genetic components of the deficits continue to elude full characterization. This review provides a characterization of these deficits by organizing findings within three frameworks of interest: 1) neuroanatomical; 2) genetic; and 3) behavioral. Within each approach, evidence from imaging studies as well as behavioral studies is examined. The hope is that by synthesizing the cognitive science paradigms, molecular genetic neurophysiological findings, and computational algorithms applied to medial temporal lobe subregions, we will be able to expand our understanding of the types of compromises in episodic memory systems of individuals with schizophrenia.     

The attentional blink: Increasing target salience provides no evidence for resource depletion. A commentary on Dux, Asplund, and Marois (2008)

The authors have argued elsewhere that the attentional blink (AB; i.e., reduced target detection shortly after presentation of an earlier target) arises from blocked or disrupted perceptual input in response to distractors presented between the targets. When targets replace the intervening distractors, so that three targets (T1, T2, and T3) are presented sequentially, performance on T2 and T3 improves. Dux, Asplund, and Marois (2008) argued that T3 performance improves at the expense of T1, and thus provides evidence for resource depletion. They showed that when T1 is made more salient (and presumably draws more resources), an AB for T3 appears to reemerge. These findings can be better explained, however, by (1) the relationship between T1 and T2 (not T1 and T3) and (2) differential salience for T3 in the long-lag condition of Dux et al.’s study. In conclusion, the Dux et al. study does not present a severe challenge to input control theories of the AB.     

Patriotism and Human Rights: An Argument for Unpatriotic Patriotism

This paper centres on the question as to whether human rights can be reconciled with patriotism. It lays out the more conventional arguments which perceive them as incommensurable concepts. A central aspect of this incommensurability relates to the close historical tie between patriotism and the state. One further dimension of this argument is then articulated, namely, the contention that patriotism is an explicitly political concept. The implicit antagonism between, on the one hand, the state, politics and patriotism, and, on the other hand, human rights, is illustrated via the work of Carl Schmitt. However, in the last few decades there has been a resurgence of interest in patriotism and an attempt to formulate a more moderate form, which tries to reconcile itself with universal ethical themes. Some of these arguments are briefly summarised; the discussion then focuses on Jürgen Habermas’s understanding of constitutional patriotism. This is seen to provide an effective response to Schmitt’s arguments. There are weaknesses in the constitutional patriotic argument which relate to its limited understanding of both the state and politics. This leads me to formulate my own argument for “unpatriotic patriotism.” The discussion then examines and responds to certain potential criticisms of this argument.     

Constructions as categories of language

What causes children to categorize distinct utterances they hear into a constructional generalization? That is, what makes subjects create a constructional category instead of treating each utterance as a distinct unrelated idiom? One simple factor that encourages the learning of abstract categories is shared concrete similarity. When instances share concrete attributes, learners are more likely to categorize them together, and moreover are more likely to attend to their abstract commonalities [Gentner, D., & Medina, J. (1998). Similarity and the development rules. Cognition, 66, 236-297; Markman, A.B., & Gentner D. (1993). Splitting the difference: A structural alignment view of similarity. Journal of Memory and Language, 32, 517-535]. This paper reports results that confirm the prediction that presentation of items with concrete shared similarity early in training enhances language learning in adults.     

The activation—selection model of meaning: Explaining why the son comes out after the sun

The activation-selection model (ASM) of determining the meaning of an ambiguous word is unique in that it is able to account for the long-term effects of meaning selection without an explicit mechanism for suppressing the representation of the nonselected meaning. The model assumes that a meaning is selected when a threshold number of attributes associated with that particular meaning are activated. When a meaning is selected, the ASM assumes that the weights of the attributes that are associated with the chosen meaning are increased. This two-phase process (transient activation followed by long-term weight changes) provides a mechanism by which meaning selection at one time can affect meaning selection at a much later time. The ASM can explain the results of the presently reported experiments, in which the meaning selected for a homophone presented in an unbiased context is affected by multiple previous presentations of the homophone in different contexts. In particular, although participants who are initially oriented toward the secondary meaning of a homophone show an increased proportion of dominant responses when next primed by the dominant meaning of the homophone, the proportion of dominant responses decreases to below baseline levels when the homophone is later presented in a neutral context, indicating the lasting influence of the initial secondary meaning context.     

Deriving meaning: Distinct neural mechanisms for metaphoric, literal, and non-meaningful sentences

In this study, we used a novel cognitive paradigm and event-related functional magnetic resonance imaging (ER-fMRI) to investigate the neural substrates involved in processing three different types of sentences. Participants read either metaphoric (Some surgeons are butchers), literal (Some surgeons are fathers), or non-meaningful sentences (Some surgeons are shelves) and had to decide whether they made sense or not. We demonstrate that processing of the different sentence types relied on distinct neural mechanisms. Activation of the left inferior frontal gyrus (LIFG), BA 47, was shared by both non-meaningful and metaphoric sentences but not by literal sentences. Furthermore, activation of the left thalamus appeared to be specifically involved in deriving meaning from metaphoric sentences despite lack of reaction times differences between literals and metaphors. We assign this to the ad hoc concept construction and open-endedness of metaphoric interpretation. In contrast to previous studies, our results do not support the view the right hemispheric is specifically involved in metaphor comprehension.     

Cortical locus of coherent motion deficits in deaf poor readers

Samar and Parasnis [Samar, V. J., & Parasnis, I. (2005). Dorsal stream deficits suggest hidden dyslexia among deaf poor readers: correlated evidence from reduced perceptual speed and elevated coherent motion detection thresholds. Brain and Cognition, 58, 300-311.] reported that correlated measures of coherent motion detection and perceptual speed predicted reading comprehension in deaf young adults. Because deficits in coherent motion detection have been associated with dyslexia in the hearing population, and because coherent motion detection is strongly dependent on extrastriate cortical area MT, these results are consistent with the claim that hidden dyslexia occurs within the deaf population and is associated with deficits in MT. However, coherent motion detection can also be influenced by subcortical deficits in both magnocellular and parvocellular pathways. To confirm the putative cortical locus of coherent motion perception deficits, we measured contrast thresholds for detecting the direction of movement of drifting sine wave gratings in the same participant group as [Samar, V. J., & Parasnis, I. (2005). Dorsal stream deficits suggest hidden dyslexia among deaf poor readers: correlated evidence from reduced perceptual speed and elevated coherent motion detection thresholds. Brain and Cognition, 58, 300-311.], under stimulus conditions that selectively biased for input from the subcortical magnocellular and parvocellular pathways, respectively. Contrast thresholds were not related to reading comprehension performance under either the magnocellular or parvocellular conditions. Furthermore, the previously reported correlations among reading comprehension, coherent motion thresholds, and perceptual speed remained significant even after contrast thresholds and non-verbal IQ were controlled in partial correlation analyses. In addition, coherent motion detection thresholds were found to correlate specifically with a reading-IQ discrepancy score, one commonly used indicator of dyslexia. These results provide direct psychophysical evidence that the previously reported deficit in coherent motion detection in deaf poor readers does not involve subcortical pathway deficits, but rather is associated with a cortical deficit likely involving area MT. They also strengthen the argument for the existence of hidden dyslexia in the deaf adult population.     

Anticipating seizure: pre-reflective experience at the center of neuro-phenomenology

The purpose of this paper is to show through the concrete example of epileptic seizure anticipation how neuro-dynamic analysis (using new mathematical tools to detect the dynamic structure of the neuro-electric activity of the brain) and "pheno-dynamic" analysis (using new interview techniques to detect the pre-reflective dynamic micro-structure of the corresponding subjective experience) may guide and determine each other. We will show that this dynamic approach to epileptic seizure makes it possible to consolidate the foundations of a cognitive non pharmacological therapy of epilepsy. We will also show through this example how the neuro-phenomenological co-determination could shed new light on the difficult problem of the "gap" which separates subjective experience from neurophysiological activity.