Autor: Ineco

Se denomina «Deterioro Cognitivo Leve” a un estado transicional entre los cambios cognitivos del envejecimiento normal y un estadio temprano de la demencia. En la actualidad, el constructo deterioro cognitivo leve (DCL) se reconoce como una condición patológica, no como un proceso normal asociado a la edad, y se utiliza específicamente para referirse a un grupo de individuos que presentan cierto grado de déficit cognitivo cuya severidad resulta insuficiente para cumplir criterios de demencia ya que no presentan un compromiso esencial en las actividades de la vida diaria (1). Originalmente el MCI refería a un déficit de memoria en el contexto de funciones no-amnésicas preservadas (DCL amnésico) pero actualmente el término incluye déficits en otras funciones cognitivas más allá de la memoria. El DCL amnésico es posiblemente un estado precursor de la enfermedad de Alzheimer. Los datos neuropatológicos confirman esta transición del DCL amnésico a enfermedad de Alzheimer.

Semantic memory is a long term memory system proposed by Tulving (2000) that stores objects, words, and general world knowledge’s meanings without connection with any particular time or place. Conceptual knowledge is mostly shared across individuals in a given culture, although its precise scope depends on the individual’s experience (Hodges & Patterson,1997; Patterson & Hodges, 1995). Semantic memory may be impaired in many neurological disorders. This disruption may be attributed to pathology in the infer-lateral temporal lobes. Patients with semantic dementia have difficulties with objects and words meanings (Budson & Price, 2005). Pyramids and Palm Trees Test is one of the most used measures to assess acquired semantic impairments (Howard & Patterson, 1992). It’s a semantic association test and has six different administration modalities: pictorial, verbal, and combined. This test contains 52 triads. The English normative data from the original Pyramids and Palm Trees Test Manual (Howard & Patterson, 1992) was only obtained in13 young adults, and no participant made morethan three errors. This is a socio-cultural influenced test. The aims of this article are to present the Pyramids and Palm Trees Test adaptation and validation to our language (Spanish) and cultural context, to compare the 52 triads from the original version with a new and shorter 20 triads version, to assess differences in performance between controls and patients in both tests, and to get cutoff scores on both versions. A computerized version of the original test (52 triads) plus 14 new triads (66 triads in total) were administered to 50 volunteers (40 controls and 10 semantic dementia patients). Presentation program was used to present the stimulus. Non frequent cultural associations were omitted: (a) windmill, tulip-daffodil, (b) carrot, lamb-donkey, (c) acorns, donkey-pig, and (d) Eskimo-rowing, boat-kayak. Also, others triads were slightly modified: (a) caterpillar, butterfly-dragonfly by caterpillar, butterfly-ant, (b) Eskimo, igloo-house by Indian, carp-house, (c) crook, sheep-mice by dog, rabbit-mice, (d) padlock, bicycle-car by pump, bicycle- car, (e) blackboard, table-desk by blackboard, pen-chalk, (f) eggs, hen-swan by flock, hen-duck, and (g) soldier, church-castle by knight, church-castle. Triads with composed words in Spanish were changed: (a) safety pin (alfiler de gancho), girl-baby by pacifier, girl-baby, (b) safe (caja fuerte),necklace-tie by jacket (chaleco), necklace-tie, and (c) bath, owl-woodpecker (pájaro carpintero) by bath, owl-canary. Of the 66 adapted triads, the 20 that allowed better discrimination between patients and controls were selected. The new and shorter version is called Pyramids and Pharaohs, because the Pyramids and Palm Trees Test triad had low specificity and moderate sensitivity in our sample and wasn´t selected. In the adapted Pyramids and Palm Trees Test the reliability index of the pictorial version was moderately high (α = .857), and high for the verbal modality (α = .910). In the Pyramids and Pharaohs Test the reliability index was high for both versions (pictorial: α = .917; verbal: α = .918). The cutoff score for the original version was 44 for the pictorial modality and 43 for the verbal modality. In the Pyramids and Pharaohs Test the cutoff score was 17 for the pictorial modality and 18 for the verbal one. Regarding the specificity, the adapted Pyramids and Palm Trees Test was high (98.8%) same as the new shorter test. In relation to the sensitivity, the original test was moderate (70%), lower than the Pyramids and Pharaohs Test (85%). Results indicate that the Pyramids and Palm Trees Test can be considered an appropriate adaptation to our social culture. Moreover a new test was designed, Pyramids and Pharaohs, with only 20 triads, adequate for semantics acquired impairments assessment, useful for the research on cognitive processes and current clinical requirements.

Tests of fluid intelligence predict success in a wide range of cognitive activities. Much uncertainty has surrounded brain lesions producing deficits in these tests, with standard group comparisons delivering no clear result. Based on findings from functional imaging, we propose that the uncertainty of lesion data may arise from the specificity and complexity of the relevant neural circuit. Fluid intelligence tests give a characteristic pattern of activity in posterolateral frontal, dorsomedial frontal, and midparietal cortex. To test the causal role of these regions, we examined fluid intelligence in 80 patients with focal cortical lesions. Damage to each of the proposed regions predicted fluid intelligence loss, whereas damage outside these regions was not predictive. The results suggest that coarse group comparisons (e.g., frontal vs. posterior) cannot show the neural underpinnings of fluid intelligence tests. Instead, deficits reflect the extent of damage to a restricted but complex brain circuit comprising specific regions within both frontal and posterior cortex.

The detection of executive deficits in early behavioral variant frontotemporal dementia (bvFTD) is crucial, as impairments in the executive domain constitute an important diagnostic feature of the newly proposed diagnostic criteria for bvFTD. Our group has recently demonstrated that classical executive tests fail to detect the executive deficits of a subgroup of early bvFTD patients. When administered an executive and social cognition battery (ESCB) that includes tasks that mimic everyday scenarios (e.g., affective decision-making, planning and organization, theory of mind), however, the performance of those bvFTD patients differed significantly from that of controls. One limitation of the ESCB is its lengthy nature (approximately 90 min). For this reason, the present study analyzes the usefulness of alternative shorter versions of this battery. We propose one particular two-task combination that demands approximately 30 min for its administration and scoring, and which presents similar discriminatory accuracy as that of the complete ESCB, while maintaining its significantly superior capacity to detect subtle executive deficits in bvFTD patients relative to classical executive tests. We suggest that, in clinical settings where tools, time, or human resources are scarce, this abbreviated ESCB may be useful in the detection of subtle yet impairing executive impairments of patients with bvFTD.

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.

A role for rostral prefrontal cortex (BA10) has been proposed in multitasking, in particular, the selection and maintenance of higher order internal goals while other sub-goals are being performed. BA10 has also been implicated in the ability to infer someone else’s feelings and thoughts, often referred to as theory of mind. While most of the data to support these views come from functional neuroimaging studies, lesion studies are scant. In the present study, we compared the performance of a group of frontal patients whose lesions involved BA10, a group of frontal patients whose lesions did not affect this area (nonBA10), and a group of healthy controls on tests requiring multitasking and complex theory of mind judgments. Only the group with lesions involving BA10 showed deficits on multitasking and theory of mind tasks when compared with control subjects. NonBA10 patients performed more poorly than controls on an executive function screening tool, particularly on measures of response inhibition and abstract reasoning, suggesting that theory of mind and multitasking deficits following lesions to BA10 cannot be explained by a general worsening of executive function. In addition, we searched for correlations between performance and volume of damage within different subregions of BA10. Significant correlations were found between multitasking performance and volume of damage in right lateral BA10, and between theory of mind and total BA10 lesion volume. These findings stress the potential pivotal role of BA10 in higher order cognitive functions.