Biomedical subjects

Marco Calabria

Publications and source records attributed to Marco Calabria.

5 recordsLinked to original sources

PubMed2006

Cognitive rehabilitation in Alzheimer's Disease.

Non-pharmacological treatment in Alzheimer's Disease has gained great attention in recent years. The limited efficacy of drug therapy and the plasticity of human central nervous system are the two main reasons that explain this growing interest in rehabilitation. Different approaches have been developed. Here we discuss the efficacy of non-pharmacological therapy in the frame of two main approaches: Multistrategy Approaches (Reality Orientation, Reminiscence Therapy and Validation Therapy) and Cognitive Methods.

Aged↗

PubMed2005

Parietal rTMS distorts the mental number line: simulating 'spatial' neglect in healthy subjects.

Patients with left-sided visuospatial neglect, typically after damage to the right parietal lobe, show a systematic bias towards larger numbers when asked to bisect a numerical interval. This has been taken as further evidence for a spatial representation of numbers, perhaps akin to a mental number line with smaller numbers represented to the left and larger numbers to the right. Previously, contralateral neglect-like symptoms in physical line bisection have been induced in healthy subjects with repetitive transcranial magnetic stimulation (rTMS) over right posterior parietal lobe. Here we used rTMS over parietal and occipital sites in healthy subjects to investigate spatial representations in a number bisection task. Subjects were asked to name the midpoint of numerical intervals without calculating. On control trials subjects' behaviour was similar to performance reported in physical line bisection experiments. Subjects underestimated the midpoint of the numerical interval. Repetitive transcranial magnetic stimulation produced representational neglect-like symptoms in number bisection when applied over right posterior parietal cortex (right PPC). Repetitive TMS over right PPC shifted the perceived midpoint of the numerical interval significantly to the right while occipital TMS had no effect on bisection performance. Our study therefore provides further evidence that subjects use spatial representations, perhaps akin to a mental number line, in basic numerical processing tasks. Furthermore, we showed that the right posterior parietal cortex is crucially involved in spatial representation of numbers.

Adult↗

PubMed2005

Interference between number processing and line bisection: a methodology.

It is usually thought that numbers are represented on a "mental number line" on which the progression of smaller to larger numbers occurs from left to right suggesting a spatial representation of numbers. Reciprocally, number processing has been shown to influence space representation [Fischer, M. (2001). Number processing induces spatial performance biases. Neurology, 822-826]. Specifically, it was found that when bisecting a string of numbers made up of smaller digits (1 or 2), the bisection was shifted to the left compared to bisecting a larger digit-string (8 or 9). In order to avoid any effect of physical difference in stimuli Here, we provide a simple methodology to investigate this relationship using a task involving the bisection of French number words (e.g."DEUX", "NEUF"). Results showed that subjects bisected strings more towards the left for smaller number words ("DEUX", 2) than for larger number words ("NEUF", 9), confirming that automatic number processing can influence visuo-motor aspects of behaviour. Similar results have been obtained with mirror versus canonical presentation, indicating that the reading direction is not the crucial factor of this number-induced bias. In addition, our sample of subjects showed a larger effect for number word strings than for Arabic number strings. It is therefore concluded that the implicit activation of the left/right side depends on the magnitude of the number being embedded within the stimulus lines, irrespective of its actual presentation format.

Adult↗

PubMed2003

Differential involvement of episodic and face representations in ERP repetition effects.

The purpose of this study was to disentangle the contribution of episodic-perceptual from pre-existing memory representations of faces to repetition effects. ERPs were recorded to first and second presentations of same and different photos of famous and unfamiliar faces, in an incidental task where occasional non-targets had to be detected. Repetition of same and different photos of famous faces resulted in an N400 amplitude decrement. No such N400 repetition-induced attenuation was observed for unfamiliar faces. In addition, repetition of same photos of faces, and not different ones, gave rise to an early ERP repetition effect (starting at approximately 350 ms) with an occipito-temporal scalp distribution. Together, these results suggest that repetition effects depend on two temporally and may be neuro-functionally distinct loci, episode-based representation and face recognition units stored in long-term memory.

Adult↗

PubMed2003

Is the N170 for faces cognitively penetrable? Evidence from repetition priming of Mooney faces of familiar and unfamiliar persons.

Impoverished images of faces, two-tone Mooney faces, severely impair the ability to recognize to whom the face pertains. However, previously seeing the corresponding face in a clear format helps fame-judgments to Mooney faces. In the present experiment, we sought to demonstrate that enhancement in the perceptual encoding of Mooney faces results from top-down effects, due to previous activation of familiar face representation. Event-related potentials (ERPs) were obtained for target Mooney images of familiar and unfamiliar faces preceded by clear pictures portraying either the same photo (same photo prime), or a different photo of the same person (different photo prime) or a new unfamiliar face (no-prime). In agreement with previous findings the use of primes was effective in enhancing the recognition of familiar faces in Mooney images; this priming effect was larger in the same than in different photo priming condition. ERP data revealed that the amplitude of the N170 face-sensitive component was smaller when elicited by familiar than by unfamiliar face targets, and for familiar face targets primed by the same than by different photos (a graded priming effect). Because the priming effect was restricted to familiar faces and occurred at the peak of the N170, we suggest that the early perceptual stage of face processing is likely to be penetrable by the top-down effect due to the activation of face representations within the face recognition system.

Adult↗