In over 1200 cases examined by isoelectric focusing of CSF and serum proteins, 4 patients had benign monoclonal gammopathy. These patients were affected by amyotrophic lateral sclerosis of bulbar onset, sensitive neuropathy of Thevenard type, myasthenia gravis, and limb-girdle muscular dystrophy, respectively. The difficulty to relate the differences in the clinical features of these cases to a common physiopathological mechanism and the incidence of this finding (0.4% in 873 cases ranging from 21-60 years of age) do not seem to suggest any pathogenetic relationship between benign monoclonal gammopathy and the different neurological disorders encountered in these patients.

Recent neuropsychological, psychophysiological and neuroimaging studies have shown that specific changes in attention and information processes occur in schizophrenic disorders. A verbal delayed reaction methodology, determined by our group since 1992, has provided similar quantitative data. Visual verbal stimuli, occurring in random sequence, are presented to the subject who is requested to utter immediately the perceived word in a first trial; in a second one, a delay (foreperiod) between the word presentation and a 'go' signal (eight asterisks) is interposed. Acousticograms and orbicularis oris EMG are recorded as responses. The ratio of the 1.5-s foreperiod delayed reaction time to the immediate reaction time reveals a facilitation of the executive system occurring during sustained purposeful attention, a characteristic function of the prefrontal cortex. A further ratio, with a 0.1-s foreperiod, has been measured to investigate the effect of interference processes. These trials have been performed including 18 patients with schizophrenia, 31 with idiopathic Parkinson's disease, four patients with extrapyramidal degenerative diseases, five affected by obsessive compulsive disorder and in age-matched normal controls. Both ratios were significantly increased in schizophrenic patients and, on the contrary, decreased in patients with obsessive-compulsive disorder. These changes are in agreement with the neuroimaging findings of 'hypofrontality' in the schizophrenic patients. Verbal delayed reaction methodology seems a reliable and easily applicable tool for investigating sustained purposeful attention processes in clinical conditions.

T-Wave Amplitude (TWA) has been suggested as an indicator of sympathetic influence on myocardial performance, but critics have argued that TWA is confounded by parasympathetic influence or that it is a non-specific feature of tachycardia. To help clarify the issue, we examined TWA as a function of parasympathetic activity, using cardiac vagal control as measured by high frequency components of heart period variability (respiratory sinus arrhythmia) and of interbeat intervals (IBI), across several stressful tasks. Sixteen male subjects were exposed to Valsalva, Serial Subtraction and Cold-Pressor tasks. After controlling for between-person variance, it was found that RSA did not contribute to TWA and that IBI contributed dependably to TWA only during the Valsalva maneuver, when heart rate was driven very high. In light of these results, we recommend that TWA continue to be considered a candidate indicator of sympathetic influence on myocardial performance, although caution should be used if heart rate is dramatically elevated.

T-Wave Amplitude (TWA) has been suggested as an indicator of sympathetic influence on myocardial performance, but critics have argued that TWA is confounded by parasympathetic influence or that it is a non-specific feature of tachycardia. To help clarify the issue, we examined TWA as a function of parasympathetic activity, using cardiac vagal control as measured by high frequency components of heart period variability (respiratory sinus arrhythmia) and of interbeat intervals (IBI), across several stressful tasks. Sixteen male subjects were exposed to Valsalva, Serial Subtraction and Cold-Pressor tasks. After controlling for between-person variance, it was found that RSA did not contribute to TWA and that IBI contributed dependably to TWA only during the Valsalva maneuver, when heart rate was driven very high. In light of these results, we recommend that TWA continue to be considered a candidate indicator of sympathetic influence on myocardial performance, although caution should be used if heart rate is dramatically elevated.

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The aim of this study was to evaluate the effects of chronic exposition to neurotoxic solvents in a group of laundry operators by means of Vocal Reaction Times (VRTs) measurements. A group of normal subjects, matched for age and educational level, constituted the controls. Vocal Reaction Times were measured by a device that presented to each subject a sequence of words on a computer screen, acquired the acoustic signal and measured VRTs and durations. During the test a random sequence of words was presented to the subjects; the protocol consisted of two immediate reading task and two delayed reading tasks. The test was performed using concrete and meaningless words. Statistical analysis showed that reaction times measured on the acoustic signals were longer for the exposed group than for the controls. The differences between durations were significant for the delayed reading tasks using concrete words and for all tasks using meaningless words. These findings suggest that this technique may be considered a useful tool for the assessment of the preclinical alterations of CNS in the monitoring of individuals chronically exposed to neurotoxic solvents.

The aim of this study was to evaluate the effects on a group of 35 laundry operators of exposure to the neurotoxic solvent perchloroethylene by means of Vocal Reaction Time (VRT) measurement. A group of 39 normal subjects comparable for age and educational level with the laundry workers constituted the controls. Vocal Reaction Times were measured by means of a device that presented Visual stimuli, acquired the acoustic signal and measured VRTs and durations. During each test a random sequence of words was presented to the subject under examination. The protocol consisted of an immediate reading task and two delayed reading tasks (the subject had to wait for. a response signal before starting to speak) in which the foreperiod was randomly selected (0.1 s or 1.5 s:). The test was performed using concrete and meaningless words. Analysis of the acoustic signals showed that reaction times were longer for the exposed group than for the controls. The differences between VRTs for the concrete words in all three tasks (immediate, 0.1 s and 1.5 s foreperiod) were statistically significant. The differences between durations were statistically significant for the delayed reading tasks using concrete words and for all tasks using meaningless words. Regression analysis showed a substantial correlation (r = 0.69, r = 0.73) between VRTs and an Exposure Index for concrete words in immediate and delayed (foreperiod = 1.5 s) reading tasks. This method can provide quantitative information about functional alterations of the nervous system areas related to speech production, in subjects exposed to neurotoxic solvents.

The aim of this study was to evaluate the effects of exposition to neurotoxic solvents in a group of laundry operators by means of Vocal Reaction Times (VRTs) measurements. A group of normal subjects, matched for age and educational level, constituted the controls. Vocal Reaction Times were measured by a device that presented to each subject a sequence of words on a computer screen, acquired the acoustic signal and measured VRTs and durations. During the test a random sequence of words was presented to the subjects; the protocol consisted of an immediate reading task and two delayed reading tasks. The test was performed using the concrete words /MARE/(sea) and /MURO/(wall) and the meaningless words /ABAVEK/ and /UBAVEK/.Statistical analysis of the acoustic signals showed that reaction times were longer for the exposed group than for the controls. The differences between durations were significant for the delayed reading tasks using concrete words and for all tasks using meaningless words. These findings suggest that the two sorts of words used may provide different information: VRTs with /MARE/ and /MURO/ seem to be more specific for evaluating motor planning processes, while duration data for /ABAVEK/ and /UBAVEK/ seem to be better for testing the muscle command preparation and execution stages.

The measurement of reaction times (RT) in response to suitable stimuli may provide insight into the separate functional blocks corresponding to diverse speech production mechanisms. The quantitative evaluation of speech motor performance provides useful information for the early detection and long-term monitoring of many neurological diseases.Speech motor performance and the effect of age were investigated by measuring vocal reaction times (VRT) and speech durations, in a group of thirty normal subjects divided into three age groups (18-44, 45-59, 60-80). VRTs were measured by using an immediate and delayed reaction stimulation paradigm. Analysis of the acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistically significant.In an attempt to classify the performance obtained in the execution of the reading tasks, and detect interference phenomena, some functionality indexes were computed.

The chronometric study of verbal reactions involves many phases, from programming and adjusting processes (Temporal Bridging) to the final neuromotor execution phase. Verbal Delayed Reactions allow us to investigate the processes of Temporal Bridging. These processes imply prefrontal functions (particularly area 46) and control not only the motor responses (as is the case in speech) but also the behavior at a high premotor level. Verbal Delayed Reactions were studied in 3 stutterers, 4 patients with spastic dysphonia, a large number of dysarthric patients (with various pathologies including amyotrophic lateral sclerosis and cerebellar disease), 17 schizophrenics and 96 age-matched normal controls. Reaction times were measured, from the acoustic and EMG signals, in a reading task with single word stimuli. A so-called intermediate process ratio (IR) was defined as the ratio of the RT at a 1.5 sec foreperiod and the RT at trials without a foreperiod (immediate responses). A specific increase in IR, without any decrease in RT at immediate responses, was found in 12 of the 17 schizophrenics. In contrast, the IR was decreased in stutterers. The impairment of delayed reactions in schizophrenia could be attributed to a functional impairment of the prefrontal system, which is involved in the timing of sequential purposeful actions like speech. This process implies inhibitory processes which play a fundamental role in motor control. In stutterers, contrary to schizophrenics, inhibitory processes are diminished and successive actions are therefore impaired.

The measurement of reaction times in response to suitable stimuli may provide insight into the separate functional blocks corresponding to diverse speech production mechanisms. The quantitative evaluation of speech motor performance provides useful information for the early detection and long-term monitoring of many neurological diseases. The vocal reaction times (VRTs) technique and its application in the assessment of a group of normal subjects is presented. Speech motor performance and the effect of age were investigated by measuring VRTs and speech duration, in a group of thirty normal subjects divided into three age groups (18-44, 45-59, 60-80). VRTs were measured by using an immediate and delayed reaction stimulation paradigm. Analysis of the acoustic and electromyographic signals indicated that reaction times increased with age in both the immediate and delayed tasks; also the acoustic signal durations increased with age. The analysis of variance showed that the difference between the young and elderly groups was statistically significant. This technique may be considered a useful tool to provide qualitative and quantitative measures of the processes involved in speech production.

We have clinically and electromyographically examined, during a follow-up study, weakened muscles and still clinically normal muscles of 9 patients affected by amyotrophic lateral sclerosis (ALS) and of 3 patients affected by focal benign amyotrophy (FBA). MRC scores corrected with positive semiquantitative evaluations of the number of giant motor unit (MU) action potentials and with negative evaluations of the number of fasciculations and fibrillations potentials have been found to linearly correlate with the percentage of the residual MUs calculated from the mean amplitude and the spike number during maximal voluntary contraction. A main finding is that the loss of MUs slows down in the last 10 months of the disease. It follows that after a phase when the pathological process was accelerated by the toxic effect due to the abnormally high concentration of glutamate released by dead motoneurons, the residual cells because of the decreased motoneuronal density are less exposed to the possible neurotoxic damage.

Forty-eight normal subjects were evaluated for the purpose of objectively quantifying muscle tone. Flexor carpi radialis and extensor digitorum communis electromyographic (EMG) activity was simultaneously recorded during wrist movements imposed by a torque motor. Each session was subdivided into three steps: (1) measurement of the 'intrinsic stiffness index' (ISI) at 10 degrees/s; (2) measurement of the 'total stiffness index' (TSI) at 500 degrees/s; (3) evaluation of the stretch reflex threshold speed (SRTS). No stretch reflex (SR) was found in about half of the subjects, even at the highest speed. ISI was higher in males (p < 0.001); significant differences in TSI were found between subjects with SR and those without (p < 0.02); no statistical differences in SRTS were found for either age or gender. ISI, TSI and SRTS, appear to be reliable indices of the range of normal muscle tone for its quantitative assessment.