Modality-specific naming deficit: cognitive and neural mechanisms implicated in naming to definition.

We report the case of an anomic patient who had a significantly greater impairment in naming to definition than in picture naming. His difficulty did not depend on the number of semantic attributes (two vs. four) or type of information (visual vs.

Dissociation between personal and extrapersonal neglect in a crossed aphasia study.

Abstract Several reports document crossed aphasia following a right cerebral infarct. However, few of them provide a detailed investigation of associated neuropsychological disorders. A personal neglect disorder with no difficulty in orienting attention in the contralesional space has not been frequently reported independently of lesion side for the language deficit.

Effect of anticonvulsants on nocturnal sleep in epilepsy.

Our objective was to determine, in three separate studies, the effects of controlled-release carbamazepine (CBZ-CR), lamotrigine (LTG), and gabapentin (GBP) on nocturnal sleep in epilepsy. Antiepileptic drugs (AEDs) control seizures and also modify hypnic structure. Despite widespread clinical use, their effects on sleep are not well known.

Muscarinic receptors depress GABAergic synaptic transmission in rat midbrain dopamine neurons.

The effects of muscarine and nicotine on evoked and spontaneous release of GABA were studied using intracellular and whole-cell patch-clamp recordings from rat midbrain dopamine neurons in an in vitro slice preparation. Muscarine (30 microM) reversibly depressed the pharmacologically isolated inhibitory postsynaptic potential evoked by local electrical stimulation. The maximal inhibition of the inhibitory postsynaptic potential amplitude was 39.

A mixed D1 and D2 antagonist does not replay pattern electroretinogram alterations observed with a selective D2 antagonist in normal humans: relationship with Parkinson's disease pattern electroretinogram alterations.

The human retina produces a tuned response to stimuli of increasing spatial frequency reversed at a steady state. The peak amplitude response, at medium spatial frequencies, is decreased in Parkinson's disease and in normal subjects (n = 18) treated with a D2 dopaminergic antagonist (l-sulpiride). Here, we report that a mixed D1-D2 receptor antagonist (haloperidol) in normal subjects (n = 18) does not produce an amplitude decrease of medium spatial frequencies (SFs) responses but it decreases low-frequency response.

Recovery of neglect after right hemispheric damage: H2(15)O positron emission tomographic activation study.

Background: The neural correlates of recovery of unilateral neglect (ULN), as well as of other consequences of focal brain damage, are largely unknown. Functional neuroimaging methods (in particular, positron emission tomography [PET]) can be applied to the in vivo study of recovery mechanisms in neurologic patients.

Objective: To evaluate the functional cerebral correlates of recovery from ULN in patients with right-sided lesions, with the use of a PET activation paradigm.

Neural control of fast-regular saccades and antisaccades: an investigation using positron emission tomography.

Regional cerebral blood flow changes related to the performance of two oculomotor tasks and a central fixation task were compared in ten healthy human subjects. The tasks were: (a) performance of fast-regular saccades; (b) performance of voluntary antisaccades away from a peripheral cue; (c) passive maintenance of central visual fixation in the presence of irrelevant peripheral stimulation. The saccadic task was associated with a relative increase in activity in a number of occipitotemporal areas.

SEPs N30 amplitude in Parkinson's disease and in pharmacologically induced rigidity: relationship with the clinical status.

The frontal N30 wave amplitude of somatosensory evoked potentials (SEPs) has been studied in 41 Parkinson's disease (PD) patients (pts) in a basal condition and compared to that of 30 normal subjects; moreover the N30 amplitude and clinical motor score have been evaluated in a subgroup of 30 PD pts before and during apomorphine infusion and in a second subgroup of 22 PD pts also during levodopa chronic therapy. The data show that N30 amplitude is decreased in PD pts in basal condition and increased following both treatments by a percentage proportional to the clinical improvement Analysis by non parametric correlations showed that the increase is well correlated to the clinical score amelioration induced by apomorphine in the more affected side. The best correlation was to rigidity score amelioration in the group of PD pts in medium stage (Hohen and Yahr stage between 2 and 3), suggesting a relationship between the rigidity and N30 amplitude decrease.

Effects of increasing doses of apomorphine during stereotaxic neurosurgery in Parkinson's disease: clinical score and internal globus pallidus activity. Short communication.

We analysed the firing activity of internal globus pallidus cells in two Parkinson's disease patients undergoing stereotaxic surgery. Both patients showed an advanced rigid-akinetic syndrome with disabling levodopa induced dyskinesias. Apomorphine, intraoperatively administered at doses (1-2 mg) inducing a short but clear clinical improvement without involuntary movements, reduced the pallidal discharge rate by > 50% in both patients.

Early visual processing in neglect patients: a study with steady-state VEPs.

Reliable steady-state visual evoked potentials (VEPs) were recorded in a group of 19 right brain-damaged patients with visuospatial hemineglect (Neglect), and two control groups: 15 left brain-damaged (LBD) patients and 12 right brain-damaged (RBD) patients without neglect. Moreover, VEPs were recorded in two rare cases of left brain damage and right visuospatial hemineglect. Stimuli were gratings phase-reversed at various temporal frequencies presented in the left and right visual field.

Eye movement patterns in reading as a function of visual field defects and contrast sensitivity loss.

Saccadic eye movements during reading were examined as a function of the side of visual field cut and the impairment of visual contrast sensitivity Five patients with various visual field defects were compared to five age-matched controls. Patients with right visual field defect showed an increase in the number of rightward saccades and a decrease in their amplitude, and patients with left visual field defects showed a pattern more similar to that of the control subjects. Two patients showed a selective deficit in the range of medium-high spatial frequency; they were the only patients to show a lengthening of mean fixation time during reading.

Neglect for low luminance contrast stimuli but not for high colour contrast stimuli: a behavioural and electrophysiological case study.

We describe a patient with a right hemisphere lesion involving the frontal lobe, the post-central gyrus and the superior parietal lobule. Behavioural testing demonstrated severe left unilateral neglect to low luminance contrast stimuli, but not to high colour contrast stimuli. Evoked potentials to low contrast luminance gratings presented in the left hemifield were not reliable.

Detecting directional hypokinesia: the epidiascope technique.

A new technique to detect directional hypokinesia is proposed.. Subjects with unilateral neglect were administered cancellation tests with an epidiascope used to dissociate visual input from motor output.

Increasing doses of l-sulpiride reveal dose- and spatial frequency-dependent effects of D2 selective blockade in the human electroretinogram.

The amplitude and phase of the second harmonic (15 Hz) of the electroretinographic responses to three different spatial frequency grating stimuli (0.25, 1 and 4 c/deg), reversed at 7.5 Hz, were studied i normal human subjects, before and 30 min after the systemic administration of three doses (0.

N30 wave amplitude of somatosensory evoked potentials from median nerve in Parkinson's disease: a pharmacological study.

We studied N20 and N30 waves of Somatosensory Evoked Potentials from median nerve stimulation in different pharmacological conditions. N30 wave amplitude was decreased in 33 parkinsonians without therapy in comparison with a group of age-matched normal subjects. In a group of 19 parkinsonians, N30 wave amplitude was significantly augmented during apomorphine infusion and less evidently, but still significantly, during chronic 1-dopa therapy.

Presence of Klùver-Bucy syndrome as a positive prognostic feature for the remission of traumatic prolonged disturbances of consciousness.

After severe brain injury a prolonged disturbance of consciousness may occur, sometimes with transient apallic syndrome (awakening without awareness of self and surroundings). Klùver-Bucy is described in the literature as a typical post-traumatic remission phase, in which the patients show an increase of oral automatisms and/or of sexual drive. The study describes Klùver-Bucy syndrome as a sign associated with favourable prognosis in the outcome of traumatic disturbances of consciousness in survivors of head trauma.

Factors affecting the clinical measurement of visuo-spatial neglect.

The present study examined a battery of tests to evaluate unilateral spatial neglect; the tests included different tasks involving several modalities of spatial exploration mapping perceptual, motor, attentional and personal or extrapersonal space dimensions. The subjects, 121 right-brain-damaged patients with unilateral neglect, were studied in seven laboratories in four European countries. Relationships among the various tests were examined by correlations, a cluster analysis and by an analysis of individual cases.