Categoría: Papers con abstracts

The Implicit Association Test (IAT) is the most popular measure to evaluate implicit attitudes. Nevertheless, its neural correlates are not yet fully understood. We examined event related potentials (ERPs) in response to face- and word processing while indigenous and non-indigenous participants performed an IAT displaying faces (ingroup and outgroup members) and words (positive and negative valence) as targets of category judgments. The N170 component was modulated by valence of words and by ingroup/outgroup face categorization. Contextual effects (face-words implicitly associated in the task) had an influence on the N170 amplitude modulation. On the one hand, in face categorization, right N170 showed differences according to the association between social categories of faces and affective valence of words. On the other, in word categorization, left N170 presented a similar modulation when the task implied a negative-valence associated with ingroup faces. Only indigenous participants showed a significant IAT effect and N170 differences. Our results demonstrate an early ERP blending of stimuli processing with both intergroup and evaluative contexts, suggesting an integration of contextual information related to intergroup attitudes during the early stages of word and face processing. To our knowledge, this is the first report of early ERPs during an ethnicity IAT, opening a new branch of exchange between social neuroscience and social psychology of attitudes.

The most selective disorder of central conceptual knowledge arises in semantic dementia, a degenerative condition associated with bilateral atrophy of the inferior and polar regions of the temporal lobes. Likewise, semantic impairment in both herpes simplex virus encephalitis and Alzheimer’s disease is typically associated with bilateral, anterior temporal pathology. These findings suggest that conceptual representations are supported via an interconnected, bilateral, anterior temporal network and that it may take damage to both sides to produce an unequivocal deficit of central semantic memory. We tested and supported this hypothesis by investigating a case series of 20 patients with unilateral temporal damage (following vascular accident or resection for tumour or epilepsy), utilizing a test battery that is sensitive to semantic impairment in semantic dementia. Only 1/20 of the cases, with a unilateral left lesion, exhibited even a mild impairment on the receptive semantic measures. On the expressive semantic tests of naming and fluency, average performance was worse in the left- than right-unilateral cases, but even in this domain, only one left-lesion case had scores consistently more than two standard deviations below control means. These results fit with recent parallel explorations of semantic function using repetitive transcranial magnetic stimulation as well as functional imaging in stroke aphasic and neurologically intact participants. The evidence suggests that both left and right anterior temporal lobe regions contribute to the representation of semantic memory and together may form a relatively damage-resistant, robust system for this critical aspect of higher cognition.

Visual perception and integration seem to play an essential role in our conscious phenomenology. Relatively local neural processing of reentrant nature may explain several visual integration processes (feature binding or figure–ground segregation, object recognition, inference, competition), even without attention or cognitive control. Based on the above statements, should the neural signatures of visual integration (via reentrant process) be non‐reportable phenomenological qualia? We argue that qualia are not required to understand this perceptual organization.

Neurodynamics of mind: The arrow illusion of conscious intentionality as downward causation. Autores Barutta J, Gleichgerrcht E, Cornejo C, Ibanez A.  Año 2010 Journal  Barutta J, Gleichgerrcht E, Cornejo C, Ibanez A.  Volumen 44(2): 127-143 Abstract   Otra información    

A neuroanatomical model of urge-for-action phenomena has been proposed based on the «motivation-for-action” network (e.g., insula and mid-cingulate cortex). Notwithstanding the sound evidence presented regarding the functional and anatomical correlates of this model, the nature of the relationship between urges and conscious awareness remains to be addressed. Moreover, this model does not seem to explain (1) how a conscious access threshold is reached, and (2) the way in which the urges are related to more general contents of consciousness.

Pavlovian trace conditioning depends on the temporal gap between the conditioned and unconditioned stimuli. It requires, in mammals, functional medial temporal lobe structures and, in humans, explicit knowledge of the temporal contingency. It is therefore considered to be a plausible objective test to assess awareness without relying on explicit reports. We found that individuals with disorders of consciousness (DOCs), despite being unable to report awareness explicitly, were able to learn this procedure. Learning was specific and showed an anticipatory electromyographic response to the aversive conditioning stimulus, which was substantially stronger than to the control stimulus and was augmented as the aversive stimulus approached. The amount of learning correlated with the degree of cortical atrophy and was a good indicator of recovery. None of these effects were observed in control subjects under the effect of anesthesia (propofol). Our results suggest that individuals with DOCs might have partially preserved conscious processing, which cannot be mediated by explicit reports and is not detected by behavioral assessment.

In order to evaluate the relationship between systemic inflammatory response and mortality in the older hospitalized patient, we developed a prospective cohort study in which we evaluated a nutritional score (SGA), years of instruction, functional status, organic failure (Marshall), presence of sepsis, comorbidities (Charlson), cognitive state (MMSE), albumin, erythrocyte sedimentation rate and mortality. Fifty two patients were included, 19 men (36.5%) and 33 women (63.5%), mean age was 80 (Interquartile Range 12.5) years. 29 (55.8%) patients were well-nourished and 23 (44.2%) malnourished, 53.8% of patients developed sepsis at admission or during hospitalization. Total nosocomial mortality was 7.7 % (n = 4) and one-year mortality was 31.8% (n = 14). Comparative analyses showed older age (80 vs. 78; p = 0.012), less years of instruction (7 vs. 8; p = 0.027), lower MMST (14 vs. 27; p = 0.017), lower previous functional status (21 vs. 32; p < 0.0001), lower albumin (3 vs. 3.35; p = 0.014) and higher organic failure score at admission (3 vs. 1; p = 0.01) with more number of affected organs (2 vs. 1; p = 0.003) in malnourished patients compared to well nourished ones. Higher incidence of sepsis -at admission or during hospitalization- (73.9% vs. 37.9%; p = 0.01) and more severe stages of sepsis were also observed in malnourished patients. One-year mortality was significantly higher in malnourished (52.2% vs. 9.5%, log rank test = 0.002). In conclusion, malnourished patients presented greater systemic inflammatory response.

The aim of this investigation was to evaluate improvement of executive functions after shunt surgery in patients with early normal pressure hydrocephalus (NPH). Patients with NPH were assessed before and after shunt surgery with tests shown to be sensitive to damage to the prefrontal cortex (PFC). Significant differences were found between basal and follow-up performances on the Boston Naming Test, the backwards digits span, Part B of the Trail Making Test, and the number of words produced on the phonological fluency task. In conclusion, our study reveals that patients with NPH who respond positively to continuous slow lumbar cerebral spinal fluid drainage and receive a ventriculoperitoneal shunt implant, improve their performance on tasks of executive function. Due to the high demand for this form of mental processing in real-life complex scenarios, and based on the severe executive deficits present in both demented and non-demented NPH patients, we encourage the assessment of executive functions in this clinical group.

It is currently accepted that there is a subset of patients diagnosed with Alzheimer’s disease (AD) who show executive functioning (EF) impairments even in the earlier stages. These patients have been shown to present distinct psychiatric, behavioral, occupational, and even histopathological profiles. We assessed thirty patients with AD on two tasks of verbal memory (Logical Memory – LM, and the Rey Auditory-Verbal Learning Task – RAVLT), as well as classical tests of EF. AD patients were classified into either a spared EF (SEF) group if they showed impaired performance (z < -1.5 SD) in none or only one of the executive tests, or into an impaired EF (IEF) group if they showed impaired performance on two or more tasks of EF. Their performance was compared with fourteen healthy controls. SEF showed significantly more years of education than IEF, but the groups did not differ significantly on age, gender, mood symptoms, or performance on general screening tests or attentional tasks. With education as a covariate, both AD groups differed from controls on all measures of memory, but a significant difference was found between SEF and IEF patients only on the recognition phases of both logical memory (p < 0.01) and RAVLT (p = 0.02). Recognition scores significantly correlated with performance on executive tasks. Early AD patients who preserve their EF seem to have an advantage in their ability to recognize information that has been previously presented over patients with impaired EF. Such advantage seems to be strongly associated with executive performance.

Traditional cognitive tests may not be sensitive for the early detection of executive and social cognitive impairments in the behavioural variant of frontotemporal dementia. The aim of this study was to detect specific executive and social cognitive deficits in patients with early behavioural variant frontotemporal dementia using a battery of tests previously shown to be sensitive to frontal lobe dysfunction. Behavioural variant frontotemporal dementia patients and paired controls were assessed with a complete standard neuropsychological battery evaluating attention, memory, visuospatial abilities, language and executive functions. All participants were then assessed with our Executive and Social Cognition Battery, which included Theory of Mind tests (Mind in the Eyes, Faux Pas), the Hotel Task, Multiple Errands Task-hospital version and the Iowa Gambling Task for complex decision-making. Patients were divided into two groups according to their Addenbrooke’s Cognitive Examination scores, a measure of general cognitive status. Low Addenbrooke’s Cognitive Examination patients differed from controls on most tasks of the standard battery and the Executive and Social Cognition Battery. While high Addenbrooke’s Cognitive Examination patients did not differ from controls on most traditional neuropsychological tests, significant differences were found between this high-functioning behavioural variant of frontotemporal dementia group and controls on most measures of our Executive and Social Cognition Battery. Our results suggest that the Executive and Social Cognition Battery used in this study is more sensitive in detecting executive and social cognitive impairment deficits in early behavioural variant of frontotemporal dementia than the classical cognitive measures.