Different types of abstract concepts: evidence from two neurodegenerative patients

The observation of neurological patients showing selective impairments for specific conceptual categories contributed in the development of semantic memory theories. Here, we studied two patients (P01, P02), affected, respectively, by the semantic variant of Primary Progressive Aphasia (sv-PPA) and Cortico-Basal Syndrome (CBS). An implicit lexical decision task, including concrete (animals, tools) and abstract (emotions, social, quantity) concepts, was administered to patients and healthy controls.P01 and P02 showed an abolished priming effect for social and quantity-related concepts, respectively. This double dissociation suggests a role of different brain areas in representing specific abstract categories, giving insights for current semantic memory theories.

Evaluating human basal metabolism: the erroneous and misleading use of so-called "prediction equations"

Prediction (regression) equations are widely used, but their reliability as predictive tools is questionable as they provide contradicting results. The key point is that values calculated by regression equations are not precisely defined numbers but lie within a range of possible values in the standard deviation interval, none of which can be considered as the most probable. Ignoring this point leads to illicit/improper calculations, generating wrong results, which may have adverse consequences for human health. To demonstrate this, we applied the equations of Harris and Benedict in a reverse method, i.e. calculating (predicting) the daily energy expenditure in the same subjects used to obtain the equations and comparing values with the original measured data. We used the Bland-Altman and frequency distribution analyses. We found large differences in both individual data and population characteristics, showing that prediction equations are not predictive tools.

Left parietal cortex transcranial direct current stimulation enhances gesture processing in corticobasal syndrome

BACKGROUND AND PURPOSE

Corticobasal syndrome (CBS) is a clinical entity characterized by higher cortical dysfunctions associated with asymmetric onset of levodopa-resistant parkinsonism, dystonia and myoclonus. One of the most typical and distressful features of CBS is limb apraxia, which affects patients in their everyday life. Transcranial direct current stimulation (tDCS) is a non-invasive procedure of cortical stimulation, which represents a promising tool for cognitive enhancement and neurorehabilitation. The present study investigated whether anodal tDCS over the parietal cortex (PARC), would improve ideomotor upper limb apraxia in CBS patients.

METHODS

Fourteen patients with possible CBS and upper limb apraxia were enrolled. Each patient underwent two sessions of anodal tDCS (left and right PARC) and one session of placebo tDCS. Ideomotor upper limb apraxia was assessed using the De Renzi ideomotor apraxia test that is performed only on imitation.

RESULTS

A significant improvement of the De Renzi ideomotor apraxia test scores (post-stimulation versus pre-stimulation) after active anodal stimulation over the left PARC was observed (χ(2) = 17.6, P = 0.0005), whilst no significant effect was noticed after active anodal stimulation over the right PARC (χ(2) = 7.2, P = 0.07). A post hoc analysis revealed a selective improvement in the De Renzi ideomotor apraxia score after active anodal stimulation over the left PARC compared with placebo stimulation considering both right (P = 0.03) and left upper limbs (P = 0.01).

CONCLUSIONS

These findings indicate that tDCS to the PARC improves the performance of an ideomotor apraxia test in CBS patients and might represent a promising tool for future rehabilitation approaches.

Prefrontal cortex rTMS enhances action naming in progressive non-fluent aphasia

BACKGROUND AND PURPOSE

Progressive non-fluent aphasia (PNFA) is a neurodegenerative disorder that is characterized by non-fluent speech with naming impairment and grammatical errors. It has been recently demonstrated that repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (DLPFC) improves action naming in healthy subjects and in subjects with Alzheimer's disease.

PURPOSE

To investigate whether the modulation of DLPFC circuits by rTMS modifies naming performance in patients with PNFA.

METHODS

Ten patients with a diagnosis of PNFA were enrolled. High-frequency rTMS was applied to the left and right DLPFC and the sham (i.e. placebo) condition during object and action naming. A subgroup of patients with semantic dementia was enrolled as a comparison group.

RESULTS

A repeated-measure anova with stimulus site (sham, left and right rTMS) showed significant effects. Action-naming performances during stimulation of both the left and right DLPFC were better than during placebo stimulation. No facilitating effect of rTMS to the DLPFC on object naming was observed. In patients with a diagnosis of semantic dementia, no effect of stimulation was reported.

CONCLUSIONS

Our study demonstrated that rTMS improved action naming in subjects with PNFA, possibly due to the modulation of DLPFC pathways and a facilitation effect on lexical retrieval processes. Future studies on the potential of a rehabilitative protocol using rTMS applied to the DLPFC in this orphan disorder are required.

The role of the dorsolateral prefrontal cortex in retrieval from long-term memory depends on strategies: a repetitive transcranial magnetic stimulation study

The ability to associate a name to a face is a crucially relevant task in daily life. In this study, we investigated the neuronal basis of face-name retrieval in young subjects using repetitive transcranial magnetic stimulation (rTMS) over the left or right dorsolateral prefrontal cortex (DLPFC). The experimental task was composed of two study phases: an encoding phase and a retrieval phase. During the encoding phase, subjects saw a face (familiar or unfamiliar) followed by a name. During the retrieval phase, they saw the face together with two names and had to choose the name that was correctly associated with the face. rTMS was delivered only during retrieval. In addition, we evaluated the use of memory strategies during the task. Accordingly, subjects were subdivided into two groups: strategy users (SU) and no-strategy users (NSU). No rTMS effects were present for familiar face-name pairs, probably due to a ceiling effect. However, for unfamiliar face-name pairs, the different use of memory strategies resulted in different rTMS effects. The SU group showed a selective interference effect after right DLPFC stimulation, whereas the NSU group showed an effect after left DLPFC stimulation. Importantly, the overall performance of the two groups was comparable. We suggest that during memory retrieval the left DLPFC might be recruited when the subject does not apply deliberately a retrieval strategy whereas there is a shift to the right DLPFC if cognitive control processes that are engaged by strategies are needed to guide episodic retrieval.

Action and object naming in Parkinson's disease without dementia

The present study aimed to assess the ability in objects and actions naming in Parkinson's disease (PD) patients. Further, we wished to assess the effect of a particular conceptual dimension, i.e. manipulability, on the naming of object and actions. Patients were recruited from the Department of Neurology, University of Brescia. Thirty-two were diagnosed as PD, according to published criteria, and 15 healthy volunteers matched in age and education to patients' sample. All patients underwent a detailed clinical and neurological evaluation. The stimuli used in the action-object picture naming task were taken from the Center for Research in Language-International Picture Naming Project corpus. To assess the effect of manipulability (or the involvement of fine hand movements) the noun-verb stimuli were re-categorized into manipulable and non-manipulable items (i.e. objects which can or cannot be manipulated and actions which do or do not involve fine hand movements). Patients showed a deficit both in action and object naming, compared with controls. In addition, patients with PD but not controls were significantly more impaired in action than in object naming. The current study supports the view that action naming is affected in patients with PD, possibly reflecting the presence of prefrontal dysfunction.

Persistent autobiographical amnesia: a case report

We describe a 47-year-old man who referred to the Emergency Department for sudden global amnesia and left mild motor impairment in the setting of increased arterial blood pressure. The acute episode resolved within 24 hours. Despite general recovery and the apparent transitory nature of the event, a persistent selective impairment in recollecting events from some specific topics of his personal life became apparent. Complete neuropsychological tests one week after the acute onset and 2 months later demonstrated a clear retrograde memory deficit contrasting with the preservation of anterograde memory and learning abilities. One year later, the autobiographical memory deficit was unmodified, except for what had been re-learnt. Brain MRI was normal while H20 brain PET scans demonstrated hypometabolism in the right globus pallidus and putamen after 2 weeks from onset, which was no longer present one year later. The absence of a clear pathomechanism underlying focal amnesia lead us to consider this case as an example of functional retrograde amnesia.

Action and object naming in frontotemporal dementia, progressive supranuclear palsy, and corticobasal degeneration

Action naming has been reported to be disproportionately impaired in comparison to object naming in patients with frontotemporal dementia (FTD). This finding has been attributed to the crucial role of frontal cortex in action naming. The investigation of object and action naming in the different subtypes of FTD, as well as in the related conditions of progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), may thus contribute to the elucidation of the cerebral correlates of the action-object discrepancy as well as provide clues to the underlying cognitive mechanisms. The results indicated that, with the exception of semantic dementia, action naming was more impaired than object naming in all patient groups. The discrepancy was similar in frontal variant of FTD and Alzheimer's disease patients, whereas patients with nonfluent primary progressive aphasia, PSP, and CBD were significantly more impaired in the oral production of actions than of objects. These findings indicate that action naming impairment is not a general feature of FTD, but rather is associated with conditions that affect the frontoparietal-subcortical circuits involved in action knowledge and action representation.

Chemical analysis and biological activity of airborne particulate matter

We examined the chemical composition of the suspended particulate matter in a typical, middle-sized, nonindustrial Italian town in terms of total carcinogenic PAH, heavy metal, and polynuclear azo-aromatic compounds. The chemical data relate to the biological activity of the organic extract of the particulate matter (mutagenicity and mice alveolar macrophage phagocytosis inhibition). The concentration values of benz(a)pyrene, the concentration ratios of selected PAH's, and the GC-MS profile of some typical samples indicate that motor vehicle traffic is the main pollution source. PAH concentration is significantly correlated with mutagenicity and a phagocytosis inhibition of up to 75% was observed at the highest PAH concentration. As far as the effect of meteorological variables on PAH concentration and mutagen-icity is concerned, a statistically significant inverse correlation with temperature was found.