Neuronal responses of the reticular and anterior ventral thalamic nuclei to stimulation of the thalamic ventrolateral nucleus and motor cortex

Responses of 137 neurons of the rostral pole of the reticular and anterior ventral thalamic nuclei to electrical stimulation of the ventrolateral nucleus and motor cortex were studied in 17 cats immobilized with D-tubocurarine. The number of neurons responding antidromically to stimulation of the ventrolateral nucleus was 10.5% of all cells tested (latent period of response 0.7–3.0 msec), whereas to stimulation of the motor cortex it was 11.0% (latent period of response 0.4–4.0 msec). Neurons with a dividing axon, one branch of which terminated in the thalamic ventrolateral nuclei, the other in the motor cortex, were found. Orthodromic excitation was observed in 78.9% of neurons tested during stimulation of the ventrolateral nucleus and in 52.5% of neurons during stimulation of the motor cortex. Altogether 55.6% of cells responded to stimulation of the ventrolateral nucleus with a discharge of 3 to 20 action potentials with a frequency of 130–350 Hz. Similar discharges in response to stimulation of the motor cortex were observed in 30.5% of neurons tested. An inhibitory response was recorded in only 6.8% of cells. Convergence of influences from the thalamic ventrolateral nucleus and motor cortex was observed in 55.7% of neurons. The corticofugal influence of the motor cortex on responses arising in these cells to testing stimulation of the ventrolateral nucleus could be either inhibitory or facilitatory.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 10, No. 5, pp. 460–468, September–October, 1978.     

Spinal cord stimulation in the treatment of spasmodic torticollis

This report presents our observations in 63 patients undergoing chronic spinal cord stimulation for treatment of spasmodic torticollis. In this series there were 23 patients (36.5%) who demonstrated marked improvement, characterized by no evidence of torticollis, full range of motility of the head and neck and no pain. Moderate improvement was found in 20 patients (31.8%) who showed minimal residual torticollis, but had full motility and no pain. There were 5 patients (7.9%) considered mildly improved who demonstrated decrease in their torticollic position, spasms and pain, but retained some element of torticollis and/or some limitation of motility. Correlations were made demonstrating the effect on the results of age, sex, electrode array, the configuration of the applied field and the parameters of stimulation.     

Impaired agonists recruitment during voluntary arm movements in patients affected by spasmodic torticollis

We have investigated the electromyographic (EMG) and kinematic characteristics of horizontal arm extension movements in patients affected by idiopathic cervical dystonia (ICD) as well as in normal subjects. In spite of the lack of an overt dystonic involvement of the muscles acting at upper arm level, all these patients were considerably bradykinetic. Although the degree of bradykinesia observed was comparable to that previously reported for the body segment directly affected by this patholgy (21,15,8), the EMG analysis of the agonist muscles indicated a specific pathophysiological mechanism. In particular, the recruitment of the posterior deltoid (pD) in ICD patients was severely impaired within the initial phase (130 ms) of the movement. On the other hand, within the same time span, the activation of the mD, a muscle that plays a more important postural role than the pD, was not significantly different between patients and normal subjects. This reduced recruitment in the initial phase of the AG1 appears responsible of the slowness of voluntary movements.     

Neuronal spike response produced in the feline thalamic reticular nucleus by instrumental conditioned reflex

Spike response was investigated in 156 units of the thalamic reticular nucleus (RN) during performance of the instrumental feeding reflex of lever-pressing. This response consisted of lead and lag phases. Latency of the lead phase of response varied between 10 and 100 msec and total duration of response between 50 and 250 msec; minimum latency of the lag phase: 100–300 msec. Initial response to a conditioning clicking sound was found in 27 units, of which 26 showed excitation and the remaining single unit an inhibitory-excitatory pattern. The lag stage of response associated with performance of conditioned lever-pressing was found in 134 neurons, of which 115 showed an excitatory pattern, 19 displayed inhibition and the remaining 22 units failed to respond. The lag phase of response preceded the onset of conditioned reflex movement (CRM) in 30 neurons. A total of 118 neurons responded between the onset of CRM and the point of lever-pressing. It was concluded that the RN plays a part in perception of the conditioned signal as well as producing and controlling performance of CRM.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 1, pp. 8–18, January–February, 1991.     

Botulinum A toxin for the treatment of adult-onset spasmodic torticollis

Thirty-five patients with adult-onset idiopathic torticollis were treated by local injections of botulinum A toxin into dystonic cervical muscles. Substantial improvement with respect to reduction and elimination of pain was found in 81 percent, improvement in posture deformity and involuntary spasms in 70 percent, increased range of motion of the neck in 78 percent, reduction in visible sternocleidomastoid hypertrophy in 86 percent, and improvement in tremor in 65 percent. The syndrome was divided into four subtypes based on pattern of dystonic muscle groups involved in the dystonia, head and shoulder posture, and sternocleidomastoid muscle hypertrophy. Injection strategy based on this subdivision is described.     

Neuronal mechanisms of interaction of Deiters nucleus with the cerebral cortex.

The effects of stimulation of the vestibular nerve and five different cerebral cortex areas on the neuronal activity of the lateral vestibular nucleus of Deiters were studied. Stimulation of the cerebral cortex is shown to lead to antidromic and synaptic activation of Deiters neurons. The synaptic potentials of Deiters neurons evoked from the cerebral cortex were of mono- and polysynaptic origin. In particular, stimulation of the cerebral cortex evoked in Deiters neurons mono- and polysynaptic excitatory postsynaptic potentials. Collaterals of vestibulospinal neurons reaching different cortex fields as well as convergence of influences from these cortex fields on Deiters neurons were revealed. Inhibitory effects of the cerebral cortex on Deiters neurons were of polysynaptic origin and occurred rarely. The topical correlation between Deiters nucleus and different areas of the cerebral cortex was found. The peculiarities and functional significance of the effects obtained are discussed.     

Neuronal response produced in the human thalamic nucleus reticularis by significant and non-significant verbal and sensory stimuli

Response recorded by microelectrode techniques during the course of 46 stereotaxic operations on dyskinesia patients was investigated in 340 units of the nucleus reticularis (rt) of the human thalamus. Differences were found between the multistage response of three types of rt neurons (A, B, and C) to verbal (or acousticcum-sensory) functionally significant stimuli (FSS) at both the stage of stimulus presentation and during the performance of goal-directed motion. Phasic activation produced by FSS presentation (as well as onset and execution of movement) in 102 out of 183 type A cells (or 55.7%) was characteristic of these cells, combined with inhibition of B type neurons in 82 out of a 139 sample (or 59.0%) produced by FSS and at the preparatory as well as the execution stage of movement. Activity of type C neurons remained unchanged. A correlation was revealed between response in A and B cells and "excitatory" trigger stimuli, but no specificity with respect to physical or semantic parameters of verbal signals. A correlation occurred during the course of movement performance with somatosensory afferents without any specific relationship to type and somatotopic aspects of movement. The time-related dynamics of A and B cell response is thought to illustrate the interaction of two neuronal subsystems within the rt participating in the performance of goal-directed motor performance triggered by speech.Institute of Chemical Physics, Academy of Sciences of the USSR, Moscow. Institute of Neurosurgery, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 4, pp. 441–451, June–July, 1990.     

Neuronal mechanisms of interaction between the red nucleus and other brain stem structures

Axon collaterals of rubrospinal neurons running to many brain stem structures were identified in acute experiments on cats by a technique of intracellular recording of antidromic action potentials in conjunction with collision testing. A systemic principle of organization of rubrospinal influences and also a tendency toward synchronous arrival of rubrospinal impulses at various brain stem centers were demonstrated. Most of these centers are relay nuclei, sending direct afferent projections to regions of the cerebellum which, in turn, control activity of the red nucleus. Besides such a loop, effecting dynamic cerebellar control over motor function, transmission of somatosensory information from nuclei of the dorsal columns of the spinal cord directly to the red nucleus was demonstrated. Special features of mono- and polysynaptic EPSPs evoked by stimulation of nuclei of the dorsal columns indicate that such PSPs arise in different regions of the soma-dendritic membrane of red nucleus neurons. The mechanisms of integration of descending motor volleys by the red nucleus are discussed.L. A. Orbeli Institute of Physiology, Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 16, No. 5, pp. 665–678, September–October, 1984.     

Effects of experimentally induced deficiency of catecholaminergic transmission on neuronal activity in the ventrolateral thalamic nucleus

Background activity was investigated in 272 neurons of the ventrolateral thalamic nucleus (VLTN) before and after systemic administration of neuroleptics (haloperidol and droperidol) at cataleptic doses by means of extracellular techniques during chronic experiments on cats. Autocorrelation and spectral analysis revealed regularly-occurring changes in the background activity rate of VLTN neurons, the periodicity of which changed by fractions of seconds (0.2–0.8 sec), seconds (1.5–10 sec), or tens of seconds (12–30 sec). While numbers of neurons with individual types of periodic activity did not exceed 6–8% in intact animals, it did increase to 18–30% after administering neuroleptics. Raised numbers of neurons with two types of regularly occurring processes within a single spike train were also noted. Experimentally-produced data were compared with findings from clinical observations. Quantities of neurons with different variations in the periodicity of their firing activity reached 19–46% in patients with parkinsonism but did not exceed 4–8% in those with torsion dystonia. The genesis of raised rhythmic firing in thalamic neurons occurring with parkinsonism is thought to be associated with impaired catecholaminergic (both dopaminergic and -adrenergic) transmission.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 22, No. 3, pp. 359–368, May–June, 1990.     

Observations and analysis of results in 131 cases of spasmodic torticollis after selective denervation

In 131 patients treated exclusively by selective denervation during the past 10 years, all or almost all the abnormal movements of spasmodic torticollis were suppressed in 115 (88%) while preserving posture and mobility. This approach was also used in certain forms of adult-onset dystonia. An appreciable amount of abnormal movements remained in the other patients, either due to residual innervation or because of limitation of denervation necessary to preserve normal movements (laterocollis) or neck stability (retrocollis). A medio-lateral approach to the posterior cervical region in the sitting position using stimulation under light anaesthesia is recommended.     

The role of ventrolateral thalamic nucleus in switching of the descending influence over to the rat motor activity

Facilitated influence of preliminary transection of the rat rubrospinal tract on motor activity and instrumental reflexes recovering after lesion of the red nucleus was more obvious after a chemical lesion rather than the electrolytic lesion. This seems to be due to remaining cerebello-thalamic fibres after a chemical lesion of the red nucleus. A preliminary destruction of the ventrolateral thalamic nucleus was shown to complicate switching of the motor activity in the rats with transected rubrospinal tract and lesioned red nucleus.     

Neuronal differentiation in the thalamic area triangularis of a lizard

Development of neurons in the area triangularis of Gallotia galloti was investigated in Golgi-impregnated brain tissue. Four major neuronal types present in adults were found to originate from two migratory neuroblast types, which were followed from embryonic stage S.32. One type has a thick main medial process, whereas the second type has a long main lateral process. As they migrate toward the periphery of the nucleus, morphological characteristics of maturation appear, including growth cones, filopodia, and outgrowth of axons. Neuroblasts with a main lateral process differentiate into two immature neuronal types, bipolars and pyramidals, observed at S.33 and thereafter. The neuroblasts with a main medial process undergo some somatic translocation through a transitory tangential shaft. Then they develop into monopolar immature forms with a long varicose medial, process, appearing from S.36. onward. Immature bipolar neurons do not experience great changes in their dendritic arborization during development to the adult stage, but pyramidals and monopolars undergo a rapid development of the dendritic tree after S.36. By S.38 archetypes of adult neuronal forms are established. Hairlike appendages first appear on neurons at S.36 They decrease suddenly in S.38 and then proliferate in S.39 when spines first appear. Around the time of hatching, the hairlike appendages begin to disappear and spines become established. Reduction of spines occurs after hatching and continues to the adult stage. Possible influences of several external factors on neuronal maturation are discussed.     

Neuronal response in nucleus reticularis thalami and neighboring thalamic structures to natural stimulation during chronic experiments on cats

Spike response was investigated in 104 neurons of the nucleus reticularis thalami (R) and adjoining thalamic nuclei to acoustic, tactile, and visual stimuli during chronic experiments on cats. Of the test neurons, 29% responded to acoustic stimulation and 11% showed no preference in relation to different acoustic stimuli. Minimum latencies of response to sounds measured 12–37 msec in excitatory and 18–27 msec in inhibitory cells. Duration of excitation produced by acoustic stimuli reached 50–250 msec; inhibition lasted 27–190 msec. Most cells belonging to this nucleus were excited by different stimuli; the proportion of inhibitory neurons did not exceed 4–10%.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 4, pp. 451–461, July–August, 1989.     

Postnatal development of thalamic reticular nucleus projections to the anterior thalamic nuclei in rats

The thalamic reticular nucleus (TRN) projects inhibitory signals to the thalamus, thereby controlling thalamocortical connections. Few studies have examined the development of TRN projections to the anterior thalamic nuclei with regard to axon course and the axon terminal distributions. In the present study, we used parvalbumin (PV) immunostaining to investigate inhibitory projections from the TRN to the thalamus in postnatal (P) 2- to 5-week-old rats (P14–35). The distribution of PV-positive (+) nerve fibers and nerve terminals markedly differed among the anterior thalamic nuclei at P14. Small, beaded nerve terminals were more distributed throughout the anterodorsal nucleus (AD) than in the anteroventral nucleus (AV) and anteromedial nucleus (AM). PV+ fibers traveling from the TRN to the AD were observed in the AV and AM. Nodular nerve terminals, spindle or en passant terminals, were identified on the axons passing through the AV and AM. At P21, axon bundles traveling without nodular terminals were observed, and nerve terminals were distributed throughout the AV and AM similar to the AD. At P28 and P35, the nerve terminals were evenly distributed throughout each nucleus. In addition, DiI tracer injections into the retrosplenial cortex revealed retrogradely-labeled projection neurons in the 3 nuclei at P14. At P14, the AD received abundant projections from the TRN and then projected to the retrosplenial cortex. The AV and AM seem to receive projections with distinct nodular nerve terminals from the TRN and project to the retrosplenial cortex. The projections from TRN to the AV and AM with nodular nerve terminals at P14 are probably developmental-period specific. In comparison, the TRN projections to the AD at P14 might be related to the development of spatial navigation as part of the head orientation system.Key words: Thalamic reticular nucleus, parvalbumin, axon terminal, development, anterior thalamic nucleus, rat     

Generation of ventralized human thalamic organoids with thalamic reticular nucleus

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