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Biomedical subjects

P Nichelli

Publications and source records attributed to P Nichelli.

At least 19 recordsLinked to original sources
PubMed2006

Bilateral posterior medullary and cervical stroke: a case report.

Spinal strokes are often localised in the anterior spinal artery territory, whereas an involvement of the posterior spinal arteries (PSA) is uncommon, and usually unilateral. Bilateral PSA stroke is exceptional. A 70-year-old woman, after a mild head trauma, presented with cervical pain, left hypoaesthesia and sensitive ataxia, which then extended to the right hemibody, including face. A Doppler ultrasound showed an only systolic flow signal in the left vertebral artery (VA). MR showed a bilateral infarction extending from the posterior medulla oblongata to C4 and a left hypoplasic VA with lack of visualisation of the V3 segment. This case was peculiar, implying a bilateral stroke in the PSA territory, possibly related to a left VA dissection, and in the presence of a dominant PSA, originating from the hypoplasic VA and of hyposupply of posterior radiculomedullary arteries and anastomoses.

Aged↗
PubMed2005

The Frontal Assessment Battery (FAB): normative values in an Italian population sample.

The Frontal Assessment Battery (FAB) is a short cognitive and behavioural six-subtest battery for the bedside screening of a global executive dysfunction; although recently devised, it is already extensively used thanks to its ease of administration and claimed sensitivity. The aim of the present study was to derive Italian normative values from a sample of 364 control subjects (215 women and 149 men) of different ages (mean: 57.4+/-17.9 years; range: 20-94 years) and educational level (mean: 10.4+/-4.3 years; range: 1-17 years); the Mini Mental State Examination (MMSE) was concurrently administered. Multiple linear regression analysis revealed significant effects for age and education whereas gender was not significant; thus, from the derived linear equation, a correction grid for FAB raw scores was built. Based on nonparametric techniques, inferential cut-off scores were subsequently determined and equivalent scores (ES) computed. Test-restest and interrater reliabilities were both satisfactory. Interestingly, MMSE was significantly correlated with FAB raw scores, whereas adjusted scores were not. The present data may improve the accuracy in the use of the FAB both for clinical and research purposes.

Adult↗
PubMed2003

Impaired facial emotion recognition in early-onset right mesial temporal lobe epilepsy.

BACKGROUND: Anteromedial temporal lobe regions, particularly the amygdala, participate in the recognition of emotions from facial expressions. The authors studied the ability of facial emotion recognition (ER) in subjects with symptomatic epilepsy, evaluating whether mesial temporal lobe damage is related to an impairment in the recognition of specific emotions and whether the onset of seizures in a critical period of life could prevent the development of ER. METHODS: Groups included patients with temporal lobe epilepsy (TLE) with MRI evidence of mesial temporal sclerosis (MTS) (n = 33); patients with TLE with MRI evidence of temporal lobe lesions other than MTS (n = 30); and patients with extratemporal epilepsy (n = 33). Healthy volunteers (n = 50) served as controls. ER was tested by matching a facial expression with the name of one of the following basic emotions: happiness, sadness, fear, disgust, and anger. A face-matching task was used to control visuoperceptual abilities with face stimuli. RESULTS: No subject showed deficits in the face-matching task. ER was impaired in patients with right MTS, especially for fearful faces. Patients presenting left MTS, right or left temporal lobe lesions other than MTS, or extratemporal seizure foci showed ER performances similar to controls. In all subjects with right TLE, the degree of emotion recognition impairment was related to age at first seizure (febrile or afebrile) and age at epilepsy onset. CONCLUSIONS: Early-onset right-sided mesial temporal lobe epilepsy is the key substrate determining a severe deficit in recognizing emotional facial expressions, especially fear.

Adolescent↗
PubMed2001

The Apolipoprotein E genotype in patients affected by syndromes with focal cortical atrophy.

The role of the Apolipoprotein E (APOE) alleles in syndromes associated with focal cerebral atrophy (fronto-temporal dementia, primary progressive aphasia, corticobasal degeneration) is still controversial. We studied the APOE allele distribution in 39 patients with clinically diagnosed syndromes associated with focal cerebral atrophy (FCA), in 50 patients with early-onset probable Alzheimer's disease (EOAD), and in 60 patients with late-onset probable AD (LOAD). The APOE genotype was determined from a blood sample, using polymerase chain reaction and restriction enzyme digestion. The APOE epsilon4 allele frequency was significantly higher in the EOAD (21.0%) and LOAD (33.3%) groups, but not in the FCA group (5.1%), as compared with controls. In our population, the epsilon2 allele frequency was significantly higher in patients with FCA (12.8%) than in controls (4.8%). These results show that the APOE epsilon4 allele is not a risk factor for syndromes associated with FCA. The potential role of the epsilon2 allele in these syndromes needs further investigation.

Age of Onset↗
PubMed2001

Explicit and incidental facial expression processing: an fMRI study.

Considerable evidence indicates that processing facial expression involves both subcortical (amygdala and basal ganglia) and cortical (occipito-temporal, orbitofrontal, and prefrontal cortex) structures. However, the specificity of these regions for single types of emotions and for the cognitive demands of expression processing, is still unclear. This functional magnetic resonance imaging (fMRI) study investigated the neural correlates of incidental and explicit processing of the emotional content of faces expressing either disgust or happiness. Subjects were examined while they were viewing neutral, disgusted, or happy faces. The incidental task required subjects to decide about face gender, the explicit task to decide about face expression. In the control task subjects were requested to detect a white square in a greyscale mosaic stimulus. Results showed that the left inferior frontal cortex and the bilateral occipito-temporal junction responded equally to all face conditions. Several cortical and subcortical regions were modulated by task type, and by facial expression. Right neostriatum and left amygdala were activated when subjects made explicit judgements of disgust, bilateral orbitofrontal cortex when they made judgement of happiness, and right frontal and insular cortex when they made judgements about any emotion.

Adult↗
PubMed2000

Selective uppercase dysgraphia with loss of visual imagery of letter forms: a window on the organization of graphomotor patterns.

We report a patient who, after a left parieto-occipital lesion, showed alexia and selective dysgraphia for uppercase letters. He showed preserved oral spelling, associated with handwriting impairment in all written production; spontaneous writing, writing to dictation, real words, pseudowords, and single letters were affected. The great majority of errors were well-formed letter substitutions: most of them were located on the first position of each word, which the patient always wrote in uppercase (as he used to do before his illness). The patient also showed a complete inability to access the visual representation of letters. As demonstrated by a stroke segmentation analysis, letter substitutions followed a rule of graphomotor similarity. We propose that the patient's impairment was at the stage where selection of the specific graphomotor pattern for each letter is made and that the apparent selective disruption of capital case was due to a greater stroke similarity among letters belonging to the same case. We conclude that a visual format is necessary neither for spelling nor for handwriting.

Aged↗
PubMed2000

Researching a differential impairment of frontal functions and explicit memory in early Parkinson's disease.

An impairment at tasks sensitive to frontal lobe damage has been repeatedly reported in Parkinson's disease, but the exact nature of these deficits has not yet been clarified. Similarly, deficits of visuo-spatial functions have been frequently observed, but it is still debated whether verbal and visuo-spatial memory can be differentially affected. In this study we have compared the performance of 20 mild Parkinson's disease patients (I-II Hoehn and Yahr stage) and 18 matched normal controls, at tasks assessing frontal functions and explicit memory. We detected a selective deficit in set shifting and maintaining, without impairment in categorization and set formation. The lack of a selective increase in perseverative errors might indicate that perseverations either measure something different from set shifting or that they do not represent an index sensitive enough to set shifting impairment. Parkinson's disease patients were also significantly impaired at Raven's Progressive Matrices, a task assessing both frontal and visuo-spatial aspects. However, they did not show any differential impairment of visuo-spatial memory. Indeed, despite a trend of lower performance in visuo-spatial learning, memory performance of Parkinson's disease patients was significantly different from that of controls only at a free recall test which involved both verbal and visuo-spatial memory. We suggest the exploration of set shifting and maintaining to detect 'frontal' deficits in mild Parkinson's disease. We argue that Raven's Progressive Matrices is a valuable task for detecting subclinical cognitive deficits in Parkinson's disease, even if it does not show a specific profile of impairment in these patients. According to our results, a differential evaluation of verbal vs. visuo-spatial memory is not necessary in clinical practice, whilst free recall confirms its usefulness to detect subclinical impairments of memory functions.

Aged↗
PubMed1999

Bilateral representation of sequential finger movements in human cortical areas.

The spatial distribution of cortical neural clusters activated during movement of either hand ('bilateral' population), or only of one hand, was investigated in healthy right-handed volunteers performing a sequential finger opposition task, using echo-planar functional magnetic resonance imaging. 'Bilateral' clusters were found in the mesial premotor, perirolandic and adjacent lateral premotor cortex of the two hemispheres, and in the left superior parietal lobule. In the precentral gyrus, their spatial extent was larger on the left hemisphere. Clusters activated exclusively during contralateral finger movements were equally distributed in the left and right perirolandic cortex. No cluster activated exclusively during ipsilateral finger movements was detected. These findings support a role of the motor/lateral premotor cortex of the dominant hemisphere in bilateral motor control.

Adult↗
PubMed1999

Selective horizontal dysmetropsia following prestriate lesion.

We describe a patient (P.S.) who, following a right prestriate lesion, reported that objects in the left visual field appeared distorted and smaller than those on the right. Other aspects of visual processing were remarkably unaffected. We carried out a series of size comparison tests using simple or complex stimuli and requiring different types of behavioural responses. We found that P.S. significantly underestimated the size of stimuli presented in her left visual field. When comparison tasks involved stimuli placed along the vertical axis or in the right visual field, P.S. performed well. The vertical and horizontal components of size distortion were found to be differentially affected. We conclude that size processing may be dissociated from other aspects of visual processing, such as form or colour processing, and depends critically on part of the occipital, prestriate areas (Brodmann areas 18-19).

Aged↗
PubMed1998

Kinematic analysis of the reach to grasp movement in Parkinson's and Huntington's disease subjects.

This experiment investigates the kinematic characteristics of the reach to grasp movement of Parkinson's and Huntington's disease subjects under two different experimental conditions. In the first condition subjects were required to perform the movement at a normal speed, while in the second condition they were required to perform the movement as fast as possible. Results showed that the kinematic parameterization of movement in Parkinson's disease subjects did not differ from that of age-matched control subjects for both the normal and the fast condition. However, the performances of Huntington's disease subjects appeared to be different when compared to the other two groups. Differences were mainly related to Huntington's disease patients' inability to properly define the temporal features of the movements.

Adult↗
PubMed1997

Impairment in dating and retrieving remote events in patients with early Parkinson's disease.

Remote memory has been studied in a group of 25 non-demented patients with Parkinson's disease and their performance has been compared with that of 22 healthy control subjects. Only patients who scored > or = 27 on the mini mental state examination and with no anticholinergic treatment were included in the sample. A remote memory questionnaire was given, to evaluate memory for public events that occurred from 1966 to 1990. Each event was probed with five questions concerning its content and one for the date. Compared with healthy subjects, patients with Parkinson's disease were significantly impaired both in recalling the content and in dating remote events. These results support the claim that remote memory in patients with Parkinson's disease is disrupted independently of dementia. This impairment might result from a dysfunction at the level of the circuit connecting the basal ganglia to the frontal lobes.

Adult↗
PubMed1996

Time perception in a neglected space.

We have studied the distortion of perceived time in a patient with left neglect. This patient consistently over-estimated the duration of stimuli in the neglected space. Overestimation was observed both with an interval comparison (300/700 ms) and with a time production (1 s) paradigm. We suggest that encoding duration in the hundreds of milliseconds range is a process based on an internal clock mechanism. The functioning of that clock varies as a function of the processing load.

Attention↗
PubMed1996

Accidental choke-cherry poisoning: early symptoms and neurological sequelae of an unusual case of cyanide intoxication.

We report the case of a 56-year-old woman who was accidentally poisoned when she ingested choke cherries whose pulp contained cyanide, and describe the acute clinical picture, the neurological sequelae and the neuroradiological findings. After recovery from coma, the patient showed signs of a parkinsonian syndrome, retrobulbar neuritis and sensory-motor neuropathy. MRI showed abnormal signal intensities involving the basal ganglia. Since no memory deficits were observed, we argue that the parkinsonian syndrome was caused by cyanide intoxication rather than by subcortical damage due to hypoxia.

Amygdalin↗
PubMed1996

Perceptual timing in cerebellar degeneration.

This study examined time perception in 12 patients with cerebellar degeneration (CD) and in 13 normal controls (NC). We used a time bisection procedure with four interval conditions (100-900 msec; 8-32 sec; 100-600 msec; 100-325 msec). Each subject's bisection point, discrimination ability (the Weber ratio) and precision (the inverse of the proportion of unexplained variance) was calculated for each condition. CD patients' performance on the 100-900 msec time bisection condition suggested a possible time discrimination deficit, which was confirmed with intervals in the range of 100-600 msec. Time discrimination was normal on the 100-325 msec condition and impaired on the 8-32 sec bisection task. However, when discriminating long intervals, CD patients also showed a precision deficit, which points to impaired sustained attention and/or decision processes. Our findings corroborate the view that cerebellar timing processes are not limited to the motor system but are also used in perceptual computations.

Adult↗
PubMed1995

Where the brain appreciates the moral of a story.

To identify the distributed brain regions used for appreciating the grammatical, semantic and thematic aspects of a story, regional cerebral blood flow was measured with positron emission tomography in nine normal volunteers during the reading of Aesop's fables. In four conditions, subjects had to monitor the fables for font changes, grammatical errors, a semantic feature associated with a fable character, and the moral of the fable. Both right and left prefrontal cortices were consistently, but selectively, activated across the grammatical, semantic, and moral conditions. In particular, appreciating the moral of a story required activating a distributed set of brain regions in the right hemisphere which included the temporal and prefrontal cortices. These findings emphasize that story processing engages a widely distributed network of brain regions, a subset of which become preferentially active during the processing of a specific aspect of the text.

Attention↗
PubMed1995

Relations between attentional and intentional neural systems.

This study explored whether preparing an arm movement influences detection of a visual stimulus. We cued subjects to respond with either a rightward or a leftward movement to the appearance of a stimulus located either in the centre, in the left, or in the right visual field. Programming a movement toward a lateral direction enhanced visual attention at that side. Rightward movements were associated with an attentional cost only for responses to a central location, while leftward movements slowed response latencies to both central and right-sided stimuli. We hypothesized that programming a rightward movement depends on the activation of intentional centers in either cerebral hemisphere. On the contrary, leftward movements might be only driven by the contralateral hemisphere.

Adult↗