Excitability relationships between lower limb myotatic arcs in spasticity.

The excitability of a lower limb myotatic reflex arc is modulated by the antecedent activation of another myotatic arc in the same limb; the changes can be represented by heteronymous excitability curves. This work compares heteronymous excitability curves in spastic and normal subjects. Eighteen patients who showed clear signs of pyramidal tract lesions at a chronic stage were studied. Three myotatic arcs of the lower limb (soleus, quadriceps, and short biceps) were activated either by mechanical percussion (T Sol-T Quad-TSBi) or by electrical stimulation of the afferent nerve (H Sol-H Quad). They were used as conditioning and test responses in six different combinations, and the results compared to those obtained previously in normal volunteers. In spastic patients, heteronymous excitability curves are more obviously modified than homonymous ones. The changes are most prominent in the thigh muscles and less marked when the soleus reflex is conditioned by activation of quadriceps and biceps femoris myotatic reflex arcs.

Analogies and differences between reserpine PGO wave discharges and oculomotor phasic activity during paradoxical sleep in the cat.

In the present study the analogies and differences between phasic PGO activity of parodoxical sleep and the reserpine induced PGO waves were investigated. The oculomotor phasic activities in chronic cats were studied. It appeared that the intrinsic organisation of latencies and the appearance of phasic waves in the four structures studied were common to both experimental situations. However the sequential patterns of discharges were different in PS and under reserpine treatment.

Sequential discharges of phasic waves in the pontine oculomotor system during paradoxical sleep in chronic mesencephalic and decorticate cats.

The temporal organization of sequences of phasic activity (PGO) in the pontine oculomotor system during paradoxical sleep was compared in normal cats, in "mesencephalic" preparations, and in completely decorticated animals. After both types of operation, PGO discharges lost their random character, becoming grouped in bursts separated by long intervals. These observations suggest that the cerebral cortex is involved in the regulation of patterns of PGO sequences.

Behavioural and electroencephalographic effects of intracerebral microinjections of sodium pentobarbital.

The effects of intracerebral microinjections of Nembutal into different brain areas, with the purpose of reproducing the behavioural and EEG signs of barbiturate narcosis, have been studied and analyzed. Cats were implanted for polygraphic study of the sleep-wakefulness cycle and bilateral brain canulae were also placed in strategic brain areas. The most striking results was the controlateral turning after unilateral injections of Nembutal in the nigra, suggesting a loss of balance among the actions of the nigro-striatal-cortical pathways on both sides. The sequence of events produced by intravestibular injections of Nembutal suggests that the drug, when injected intraperitoneally, acts also upon the vestibular system. This data stresses the importance of localized intracerebral microinjections of drugs to determine and differentiate their action mechanisms when injected in an intraperitoneal or intravenous way.

Sequential discharges of phasic activities (PGO waves) during paradoxical sleep after selective cortical lesions in the cat.

We investigated the role that cortical areas have upon the sequences of PGO waves and associated phasic activity in the lateral rectus muscles of the eyes (PALRE) during PS. We performed several combined type of lesions (bilateral ablations of frontal lobes carried out in two sessions, or occipital lesions combined with bifrontla lobotomies). We used statistical methods previously described for the normal cat (4). We showed that frontal lesions need to be bilateral in order to be effective, that thereafter there is a recovery in the complexity of the patterns in the survival period. We showed that occipital lobectomies "per se" do not affect the PGO pattern, but their combination with bifrontal lobotomies produce the most dramatic changes which lasted throughout the survival period. These findings are discussed on the light of the well known anatomical cortical projections to brain stem structures which participate in the determinism of PGO waves during paradoxical sleep.

'Binding' of glutamate and asparatate to synaptosomal fractions of six regions of the feline brain.

The order of potency of 'binding' of both glutamate and aspartate to synaptosomal fractions of brain regions was: cerebellar cortex greater than caudate nucleus greater than or equal to cerebral cortex greater than medulla approximately pons greater than corona radiata. Glutamate was bound to a greater extent than aspartate to particles of all regions studied, except for cerebral cortex.

Tele-encephalic versus cerebellar control upon ponto-geniculo-occipital waves during paradoxical sleep in the cat.

Studying the effects that removal of the cerebellum and the frontal lobes had upon the phasic activities (PGO waves) of paradoxical sleep in the cat, it is shown that in this phase of the sleep-wakefulness cycle the cerebellum exerts an inhibitory action upon the amplitude of the GPO, while the frontal lobes influences the pattern of their discharges.

Water contents of various regions of the feline nervous system.

A systematic analysis of the regional water content of the feline nervous system was made. In general, areas rich in grey matter contained about 10-15% more water than white matter areas. Percentage water values were lowest for cranial and peripheral nerves and highest for cerebral cortex, cerebellar cortex, olfactory bulb and other grey matter regions. Values for cerebral cortex varied from about 81.5% for suprasplenic gyrus to over 84% for frontal gyrus. It is suggested that the effective concentrations of dissolved substances in various regions of the nervous system might be influenced greatly by these differences in water content.

Binding of gamma-aminobutyric acid and taurine to synaptosomal fractions of regions of the feline CNS.

The "binding" of 3H-gamma-aminobutyric acid (3H-GABA) and 14C-taurine (7 X 10(-5) M) to synaptosomal fractions of the feline CNS was studied using differential centrifugation and double-isotope methods. Of the regions examined, the "binding" of GABA (in nmole/mg protein) occurred to the greatest extent, in cerebral cortex, olfactory bulb, and colliculi and, to a lesser extent, in caudate nucleus, corona radiata, and fornix. Distribution ratios revealed that GABA binding was greater in the cerebral cortex than in caudate nucleus, brain stem, spinal cord, and white matter regions. The binding of taurine (in nmole/mg protein) was lowest in cerebral cortex and highest in brain stem and spinal gray regions. Distribution ratios for taurine indicated that its accumulation was similar in all CNS regions studied, except for slightly higher values for cerebellar cortex and fornix. These results indicated that preferential binding of both GABA and taurine exists among regions of the feline CNS.