Selective impairment of living things and musical instruments on a verbal 'Semantic Knowledge Questionnaire' in a case of apperceptive visual agnosia

Semantic memory was investigated in a patient (MR) affected by a severe apperceptive visual agnosia, due to an ischemic cerebral lesion, bilaterally affecting the infero-mesial parts of the temporo-occipital cortices. The study was made by means of a Semantic Knowledge Questionnaire (Laiacona, Barbarotto, Trivelli, & Capitani, 1993), which takes separately into account four categories of living beings (animals, fruits, vegetables and body parts) and of artefacts (furniture, tools, vehicles and musical instruments), does not require a visual analysis and allows to distinguish errors concerning super-ordinate categorization, perceptual features and functional/encyclopedic knowledge. When the total number of errors obtained on all the categories of living and non-living beings was considered, a non-significant trend toward a higher number of errors in living stimuli was observed. This difference, however, became significant when body parts and musical instruments were excluded from the analysis. Furthermore, the number of errors obtained on the musical instruments was similar to that obtained on the living categories of animals, fruits and vegetables and significantly higher of that obtained in the other artefact categories. This difference was still significant when familiarity, frequency of use and prototypicality of each stimulus entered into a logistic regression analysis. On the other hand, a separate analysis of errors obtained on questions exploring super-ordinate categorization, perceptual features and functional/encyclopedic attributes showed that the differences between living and non-living stimuli and between musical instruments and other artefact categories were mainly due to errors obtained on questions exploring perceptual features. All these data are at variance with the 'domains of knowledge' hypothesis', which assumes that the breakdown of different categories of living and non-living things respects the distinction between biological entities and artefacts and support the models assuming that 'category-specific semantic disorders' are the by-product of the differential weighting that visual-perceptual and functional (or action-related) attributes have in the construction of different biological and artefacts categories.     

Twenty-four hours of total sleep deprivation selectively impairs attentional networks

Performance decrements after sleep loss have been extensively studied and are usually attributed to generic attentional deficits. This claim, however, is based on the view of attention as a unitary construct, despite evidence that it should be considered a multidimensional cognitive ability. The aim of the present study was to evaluate the impact of one night of sleep deprivation on the efficiency of three attentional networks, defined by Posner and Raichle (1994) in anatomical and functional terms, as alerting, orienting, and executive control. Thirty participants performed the Attention Network Test at 9:00 a.m. following two different sleep conditions: baseline (a normal night of sleep) and deprivation (24 hrs of wakefulness). Results showed an overall slowing in reaction times and a significant decrease in accuracy after sleep deprivation. Sleep deprivation selectively affected the three attentional networks, given that only executive control efficacy significantly decreased after sleep deprivation. By contrast, phasic alerting and orienting showed no differences in the two sleep conditions. Thus, performance deficits following sleep deprivation do not reflect global attentional deficits.     

Intraoperative conversion to open technique: is informed consent implied?

This case raises issues regarding the anesthesia and surgical components of preoperative informed consent and the differing views of anesthesiologists and surgeons with regards to informed consent, in the context of conversion to open surgery from a minimally invasive approach.     

On the nature of nonverbal working memory fractionation: a case of selective spatial short-term memory deficit in a child

Several lines of research on adult subjects demonstrate a visual/spatial fractionation of nonverbal working memory (WM), while behavioral studies on normal children support the idea of a static/dynamic distinction. In the present paper, we report a child (Z.M.) who failed on nonverbal WM tasks. To verify the nature of his defect, we carried out two experiments: in Experiment 1, Z.M. failed on spatial WM tasks but not on visual WM tasks and was not affected by the static/dynamic format of stimulus presentation; in Experiment 2, this visual/spatial dissociation was extended to the imagery domain. These results are best accounted for within the visual/spatial fractionation of WM and confirmed the role of WM in mental imagery. Clinical and rehabilitative implications of the present findings are also discussed.     

A place for nouns and a place for verbs? A critical review of neurocognitive data on grammatical-class effects

It is generally held that noun processing is specifically sub-served by temporal areas, while the neural underpinnings of verb processing are located in the frontal lobe. However, this view is now challenged by a significant body of evidence accumulated over the years. Moreover, the results obtained so far on the neural implementation of noun and verb processing appear to be quite inconsistent. The present review briefly describes and critically re-considers the anatomo-correlative, neuroimaging, MEG, TMS and cortical stimulation studies on nouns and verbs with the aim of assessing the consistency of their results, particularly within techniques. The paper also addresses the question as to whether the inconsistency of the data could be due to the variety of the tasks used. However, it emerged that neither the different investigation techniques used nor the different cognitive tasks employed fully explain the variability of the data. In the final section we thus suggest that the main reason for the emergence of inconsistent data in this field is that the cerebral circuits underlying noun and verb processing are not spatially segregated, at least for the spatial resolution currently used in most neuroimaging studies.     

Inducing disbelief in free will alters brain correlates of preconscious motor preparation: the brain minds whether we believe in free will or not

The feeling of being in control of one's own actions is a strong subjective experience. However, discoveries in psychology and neuroscience challenge the validity of this experience and suggest that free will is just an illusion. This raises a question: What would happen if people started to disbelieve in free will? Previous research has shown that low control beliefs affect performance and motivation. Recently, it has been shown that undermining free-will beliefs influences social behavior. In the study reported here, we investigated whether undermining beliefs in free will affects brain correlates of voluntary motor preparation. Our results showed that the readiness potential was reduced in individuals induced to disbelieve in free will. This effect was evident more than 1 s before participants consciously decided to move, a finding that suggests that the manipulation influenced intentional actions at preconscious stages. Our findings indicate that abstract belief systems might have a much more fundamental effect than previously thought.     

Recognition and mental manipulation of body parts dissociate in locked-in syndrome

Several lines of evidence demonstrate that the motor system is involved in motor simulation of actions, but some uncertainty exists about the consequences of lesions of descending motor pathways on mental imagery tasks. Moreover, recent findings suggest that the motor system could also have a role in recognition of body parts. To address these issues in the present study we assessed patients with a complete damage of descending motor pathways (locked-in syndrome, LIS) on the hand laterality task, requiring subjects to decide whether a hand stimulus in a given spatial orientation represents a left or a right hand. LIS patients were less accurate than healthy controls in judging hand laterality; more importantly, LIS patients’ performance was modulated by spatial orientation of hand stimuli whereas it was not affected by biomechanical constraints. These findings demonstrate a dissociation between spared hand recognition and impaired access to action simulation processes in LIS patients.     

Homeostatic Property Cluster Theory without Homeostatic Mechanisms: Two Recent Attempts and their Costs

Journal for General Philosophy of Science - The homeostatic property cluster theory (HPC) is widely influential for its ability to account for many natural-kind terms in the life sciences. However,...