- Email: [email protected]
Lunch raise the cerebral blood flow of healthy human beings
Socieiy P < 0.0001). with a 0.09 Hz/year reduction estimated from the regression function for the age interval. No correlation was observed in controls matching for age, while a significant trend of reduction (linear regression; t = -4.082; P < 0.001; estimated 0.02 Hz/year) was observed in controls of 15-80 years of age. The estimated increase of ERG b wave latency (t = 2.16, P < 0.05) was 0.29 ms/year (0.08 ms/year in normals). These observations add to the evidence of functional peculiarities in the CNS aging processes of Down’s subjects. 54.
Neurophysiology glia: experimental Bernardi (Clinica Vergata, Roma)
and neuropharmacology approach and clinical Neurologica Dip. Sanith,
of the basal ganimplications. - G. Universita di Tor
Alterations of the basal ganglia system have been shown to cause movement disorders such as Parkinson’s disease and choreic syndromes. In recent years, in our laboratory we have utilized rat brain slice preparations and intracellular recordings to analyze the electrophysiological and pharmacological properties of both nigral and striatal neurons which play a major role in the control of the basal ganglia activity. Dopaminergic nigral neurons show spontaneous firing activity which is regulated by different voltage-dependent conductances. Application of dopaminergic agonists causes membrane hyperpolarization of nigral neurons: this event is induced by a D2 receptor-mediated activation of potassium conductances. Different drugs, utilized in Parkinson’s disease and depressive disorders, mimic the effects of dopamine and increase the dopamine mediated-responses. Striatal neurons show very high resting membrane potential; in these cells tiring discharge is mainly caused by cortical glutamatergic inputs. Activation of Dl dopamine receptors inhibits current-evoked tiring discharge of striatal cells. In contrast, activation of D2 dopamine receptors does not cause significant effects in control condition, but it reduces the amplitude of cortically evoked synaptic potentials in dopamine-depleted slices. Furthermore we have recently shown an important role of endogenous dopamine in the generation of long term synaptic depression of the corticostriatal transmission, a novel form of synaptic plasticity within the basal ganglia. We suggest that the use of experimental neuropharmacology may provide some insights in understanding the pathophysiology of movements disorders. 55.
Induction tests for psychogenic seizures (Neurological Institute Univ., Bologna)
(PS).
- P. Tinuper
Differential diagnosis between epileptic and pseudoepileptic seizures is based upon clinical background, semeiological features and video-EEG recordings with direct observation of attacks. Recorded PS must have the same semeiological characteristics as the anamnestic attacks. During prolonged EEG recordings PS may appear spontaneously or may be inducted by routine activation (hyperventilation and intermittent light stimulation). Moreover PS may be induced by suggestion coupled with placebo administration (E.V., I.M. or percutaneous). PS may be induced and also stopped by these procedures so its specificity is very high. EEG is useful for diagnosis if ictal epileptic discharges are recorded. EEG is not significant if no paroxysmal discharge appears. 56.
Digit-probe identification and matching in short-term memory: the effects of serial position on reaction time, performance and event-related potentials. - A. Grippo, G Tognonia, L.D. Blumhardtb (Nemophysiological Unit, Civic Hospital, Viareggio, aDept. of Clinical Neurophysiology, University of Pisa, bDivision of Clinical Neurol., University Hospital, Nottingham, UK)
The Stemberg paradigm has been frequently utilized in neuropsychology and in neurophysiology, to evaluate short-term memory, The original hypothesis of exhaustive scanning of the memory traces has
Proceedings
65P
been confirmed in many studies using behavioral data, but the evidence for scanning in ERPs is controversial. In the present study we have examined the effect of serial position on retrieval/matching in the Stemberg task as a function of the set size of the memory set, utilizing behavioral data, i.e. reaction time (RT) and error scores, and eventrelated potentials (ERPs). We studied 12 healthy subjects (6 male and 6 female) using a modified auditory Stemberg paradigm. The subjects were asked to retain sets of digits at four level of memory set size (I, 3, 5 and 7 digits) in different blocked trials. The subjects had to decide wether a probe digit presented 3 s after the memory set items, had been present or absent from the preceding set. The ERPs and behavioral data were analyzed as a function of the probe position in the memory set. The RT and error scores showed a strong effect of recency (most evident in the memory sets of sets of 5 and 7 digits) and little if any evidence of primacy. The ERPs to probes of items in the last position of the memory sets showed a significant amplitude increase in the latency range of 420-577 ms. Our results suggests that retrieval and matching strategies vary with the memory load. Exhaustive scanning appears to be used for low memory load, but alternative mechanisms operate at higher memory loads. 57.
Lunch raises the - G. Rodriguez, (Dept. of Motor Neurophysiology
cerebral blood flow of healthy human beings. F. Nohili, M. Sara, A. Arrigo, G. Rosadini Sciences, University and Center for Cerebral (CNR), Genova, Italy)
The effect of meal on regional cerebral blood flow (rCBF) is unknown. In 16 healthy volunteers ( 10 men, 19-33 years) rCBF (133. xenon) was measured at midday; at 1 p.m. a standard lunch was administered (1 hg pasta with tomato sauce, a I hg steak. a mixed salad. an apple, a glass of red wine, water). One hour (group A, 8 subjects) or 90 min (group B, 8 subjects) after the end of lunch, rCBF was rcmeasured. A global CBF value and an antero-posterior CBF ratio were computed in each subject and average values were computed in each group. Expired pCO2 (PeCOz), heart rate, blood pressure, and respiratory rate were measured at the 2nd minute of each examination. Regional CBF values were constdered as both raw (rCBF) and PeCG-corrected values (rCBF-corr). Both rCBF and rC; BF-corr. increased in all group A subjects, with a statistically significant (t test; I’< 0.01) difference in comparison to midday examination; in group B, rCBF increased in 3 subjects and ICBF-corr. in 5. without significant differences versus the midday exam. No other parameter showed significant differences. It could be hypothesized that substances derived from the gastrointestinal tract, such as vasoactive polipeptides and gastrointestinal hormones, with a relatively short half-life. might act on cerebrovascular vessels or on cerebral metabolism. 58.
Cerebral hypoperfusion in hypertensive patients with normal cerebral magnetic resonance imaging (MRI). - F. Nobili, G. Rodriguez, F. Sardanellia, E. Melania, A. Arrigo, A. CastaId?‘, G. Rosadini (Dept. of Motor Sciences, University and Center for Cerebral Neurophysiology (CNR). aDept. of Radiology, University, Genova)
Neurologically asymptomatic hypertensives may show global or focal cerebral hypoperfusion, whose relationship with ischemic cerebral lesions is uncertain. In I3 treated (good control = [+I: 9 cases; poor = [-] in 4) hypertensives (mean age 57 years,) with previous cerebral hypoperfusion (133.xenon), cerebral MRI (0.5 T) and a second regional cerebral blood flow (tCBF) examination were performed. Gut of the 4 diffusely hypoperfused patients, all had a normal MRI: in 2 rCBF was unchanged (1 [+I, 1[-I) and in 2 [+] it recovered to normal. In the other 9 patients. rCBF was unchanged in 6 (3: 2[+], 1 [-I) with multiple MRI white matter abnormalities; I 1-1 with a cerebellar MRI abnormality; 2 [+] with a normal MRI). normalized or improved in 2 [+] with a normal N31, worsened in I [-] due to the enlargement of hypoperfusion (MRI white matter abnormalities). Therefore, in all the 4
Neurophysiology glia: experimental Bernardi (Clinica Vergata, Roma)
and neuropharmacology approach and clinical Neurologica Dip. Sanith,
of the basal ganimplications. - G. Universita di Tor
Alterations of the basal ganglia system have been shown to cause movement disorders such as Parkinson’s disease and choreic syndromes. In recent years, in our laboratory we have utilized rat brain slice preparations and intracellular recordings to analyze the electrophysiological and pharmacological properties of both nigral and striatal neurons which play a major role in the control of the basal ganglia activity. Dopaminergic nigral neurons show spontaneous firing activity which is regulated by different voltage-dependent conductances. Application of dopaminergic agonists causes membrane hyperpolarization of nigral neurons: this event is induced by a D2 receptor-mediated activation of potassium conductances. Different drugs, utilized in Parkinson’s disease and depressive disorders, mimic the effects of dopamine and increase the dopamine mediated-responses. Striatal neurons show very high resting membrane potential; in these cells tiring discharge is mainly caused by cortical glutamatergic inputs. Activation of Dl dopamine receptors inhibits current-evoked tiring discharge of striatal cells. In contrast, activation of D2 dopamine receptors does not cause significant effects in control condition, but it reduces the amplitude of cortically evoked synaptic potentials in dopamine-depleted slices. Furthermore we have recently shown an important role of endogenous dopamine in the generation of long term synaptic depression of the corticostriatal transmission, a novel form of synaptic plasticity within the basal ganglia. We suggest that the use of experimental neuropharmacology may provide some insights in understanding the pathophysiology of movements disorders. 55.
Induction tests for psychogenic seizures (Neurological Institute Univ., Bologna)
(PS).
- P. Tinuper
Differential diagnosis between epileptic and pseudoepileptic seizures is based upon clinical background, semeiological features and video-EEG recordings with direct observation of attacks. Recorded PS must have the same semeiological characteristics as the anamnestic attacks. During prolonged EEG recordings PS may appear spontaneously or may be inducted by routine activation (hyperventilation and intermittent light stimulation). Moreover PS may be induced by suggestion coupled with placebo administration (E.V., I.M. or percutaneous). PS may be induced and also stopped by these procedures so its specificity is very high. EEG is useful for diagnosis if ictal epileptic discharges are recorded. EEG is not significant if no paroxysmal discharge appears. 56.
Digit-probe identification and matching in short-term memory: the effects of serial position on reaction time, performance and event-related potentials. - A. Grippo, G Tognonia, L.D. Blumhardtb (Nemophysiological Unit, Civic Hospital, Viareggio, aDept. of Clinical Neurophysiology, University of Pisa, bDivision of Clinical Neurol., University Hospital, Nottingham, UK)
The Stemberg paradigm has been frequently utilized in neuropsychology and in neurophysiology, to evaluate short-term memory, The original hypothesis of exhaustive scanning of the memory traces has
Proceedings
65P
been confirmed in many studies using behavioral data, but the evidence for scanning in ERPs is controversial. In the present study we have examined the effect of serial position on retrieval/matching in the Stemberg task as a function of the set size of the memory set, utilizing behavioral data, i.e. reaction time (RT) and error scores, and eventrelated potentials (ERPs). We studied 12 healthy subjects (6 male and 6 female) using a modified auditory Stemberg paradigm. The subjects were asked to retain sets of digits at four level of memory set size (I, 3, 5 and 7 digits) in different blocked trials. The subjects had to decide wether a probe digit presented 3 s after the memory set items, had been present or absent from the preceding set. The ERPs and behavioral data were analyzed as a function of the probe position in the memory set. The RT and error scores showed a strong effect of recency (most evident in the memory sets of sets of 5 and 7 digits) and little if any evidence of primacy. The ERPs to probes of items in the last position of the memory sets showed a significant amplitude increase in the latency range of 420-577 ms. Our results suggests that retrieval and matching strategies vary with the memory load. Exhaustive scanning appears to be used for low memory load, but alternative mechanisms operate at higher memory loads. 57.
Lunch raises the - G. Rodriguez, (Dept. of Motor Neurophysiology
cerebral blood flow of healthy human beings. F. Nohili, M. Sara, A. Arrigo, G. Rosadini Sciences, University and Center for Cerebral (CNR), Genova, Italy)
The effect of meal on regional cerebral blood flow (rCBF) is unknown. In 16 healthy volunteers ( 10 men, 19-33 years) rCBF (133. xenon) was measured at midday; at 1 p.m. a standard lunch was administered (1 hg pasta with tomato sauce, a I hg steak. a mixed salad. an apple, a glass of red wine, water). One hour (group A, 8 subjects) or 90 min (group B, 8 subjects) after the end of lunch, rCBF was rcmeasured. A global CBF value and an antero-posterior CBF ratio were computed in each subject and average values were computed in each group. Expired pCO2 (PeCOz), heart rate, blood pressure, and respiratory rate were measured at the 2nd minute of each examination. Regional CBF values were constdered as both raw (rCBF) and PeCG-corrected values (rCBF-corr). Both rCBF and rC; BF-corr. increased in all group A subjects, with a statistically significant (t test; I’< 0.01) difference in comparison to midday examination; in group B, rCBF increased in 3 subjects and ICBF-corr. in 5. without significant differences versus the midday exam. No other parameter showed significant differences. It could be hypothesized that substances derived from the gastrointestinal tract, such as vasoactive polipeptides and gastrointestinal hormones, with a relatively short half-life. might act on cerebrovascular vessels or on cerebral metabolism. 58.
Cerebral hypoperfusion in hypertensive patients with normal cerebral magnetic resonance imaging (MRI). - F. Nobili, G. Rodriguez, F. Sardanellia, E. Melania, A. Arrigo, A. CastaId?‘, G. Rosadini (Dept. of Motor Sciences, University and Center for Cerebral Neurophysiology (CNR). aDept. of Radiology, University, Genova)
Neurologically asymptomatic hypertensives may show global or focal cerebral hypoperfusion, whose relationship with ischemic cerebral lesions is uncertain. In I3 treated (good control = [+I: 9 cases; poor = [-] in 4) hypertensives (mean age 57 years,) with previous cerebral hypoperfusion (133.xenon), cerebral MRI (0.5 T) and a second regional cerebral blood flow (tCBF) examination were performed. Gut of the 4 diffusely hypoperfused patients, all had a normal MRI: in 2 rCBF was unchanged (1 [+I, 1[-I) and in 2 [+] it recovered to normal. In the other 9 patients. rCBF was unchanged in 6 (3: 2[+], 1 [-I) with multiple MRI white matter abnormalities; I 1-1 with a cerebellar MRI abnormality; 2 [+] with a normal MRI). normalized or improved in 2 [+] with a normal N31, worsened in I [-] due to the enlargement of hypoperfusion (MRI white matter abnormalities). Therefore, in all the 4