Types Of Spontaneous Activity Research Articles

Biomechanics of the urinary bladder: spontaneous contraction activity and micromotions related to accommodation.

Knowledge of the fundamental properties of the urinary bladder is required to better understand its pathological conditions. Research on the passive and active properties of the bladder during stretching and contraction is important. The bladder is not passive during the filling phase. Spontaneous contractions are observed as variations in pressure, which are mostly related to urgency and/or incontinence and sometimes to pelvic pain. The purpose of this study was to describe distributed spontaneous contractions and micromotions (MMs), which besides being related to symptoms, are crucial in the physiological process of accommodation, and to express accommodation in a concept. After describing MMs in the bladder wall as the type of spontaneous activity that may not be reflected in detrusor pressure and as a source of afferent nerve activity, its biomechanical effects are considered. In a simple mechanical model, contractions and elongations are related to the plastic elongated state of the bladder. The changing distributed character of contractions and elongations in the bladder wall is represented in a modular scheme. Distributed transient contractions and MMs yield a balanced dynamic plastic state of the regions of the bladder wall. An almost constant detrusor pressure can be attributed to the active accommodation of detrusor pressure to changes in bladder volume. Localized contractile activity and MMs that change the plastic elongated state of varying bladder regions are biomechanically effective in the active accommodation of detrusor pressure to changes in bladder volume. According to this concept, autonomous bladder wall activity as a source of nerve activity, also is crucial for active accommodation.

Effect of Purine Co-Transmitters on Automatic Activity Caused by Norepinephrine in Myocardial Sleeves of Pulmonary Veins.

We studied the effect of extracellular purine nucleotides (NAD+ and ATP) on spontaneous arrhythmogenic activity caused by norepinephrine in myocardial sleeves of pulmonary veins. In pulmonary veins, NAD+ and ATP reduced the frequency of action potentials and their duration at regular type of spontaneous activity caused by norepinephrine. NAD+ and ATP lengthened the intervals between spike bursts at periodic (burst) type of spontaneous activity. In addition, ATP shortened the duration of spike bursts and the number of action potentials in the "bursts" caused by norepinephrine in the pulmonary veins. It was hypothesized that NAD+ and ATP attenuate the effects of sympathetic stimulation and when released together with norepinephrine from sympathetic endings in vivo, probably, reduce arrhythmogenic activity in myocardial sleeves of pulmonary veins.

89. Segmental muscular neurogenic hypertrophy: Two case reports with different site of lesion

The usual semiotic sign of motor neuron damage is hypotrophy of target muscle. However, in rare cases, a motor neuron damage results in hypertrophy: this is principally due to a chronic triggering of spontaneous activity in affected motor units, with continuous or subcontinuous activation of target muscular fibers. Muscular neurogenic hypertrophy was reported during radiculopathy, mononeuropathy, focal myelopathy, tethered cord syndrome, chronic inflammatory demyelinating polyneuropathy. In this report we present classification of muscular neurogenic hypertrophy, based on topography, etiology and type of spontaneous activity possibly observed. We present also two cases: the first one due to spondyloarthrosis associated with T11–T12 discopathy, the second one due to ischiatic nerve neuropathy related to proximal femur fracture.

Electrodiagnosis of the Peripheral Nervous System: An Introduction

Abstract This article is an introduction to electrodiagnosis of the peripheral nervous system, including electromyography, electroneurography (nerve conduction studies), and somatosensory evoked potentials. Electromyography involves the introduction of a special recording needle into a muscle body in search of spontaneous activity (electrical potentials that occur while the muscle is at rest). Three types of spontaneous activity are of greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations. Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS involves the introduction of an electrical stimulus, either by surface electrode or needle, and recording an evoked response. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks, depending on the strategy employed. Somatosensory evoked potentials (SSEP) sometimes are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology and are obtained by stimulating a peripheral mixed nerve at a frequency of approximately 2-5 Hz. Several manufacturers have created automated, hand-held units for performing nerve conduction studies, and neuromuscular ultrasound is noninvasive and painless, and ultrasound of nerve entrapment has identified nerve enlargement just proximal to the site of entrapment. Physicians should know or learn the qualifications of the physician to whom they refer their patients for electrodiagnostic assessment.

The role of intra-striatal synaptic interactions for shaping cortico-striatal network dynamics

Event Abstract Back to Event The role of intra-striatal synaptic interactions for shaping cortico-striatal network dynamics Jovana Belić1*, Andreas Klaus2, Dietmar Plenz3 and Jeanette Hellgren Kotaleski4 1 Royal Institute of Technology (KTH), Stockholm and Bernstein Center Freiburg, Sweden 2 Karolinska Institutet (KI), Stockholm and National Institute of Mental Health (NIH), Bethesda, USA, United States 3 National Institute of Mental Health (NIH), Bethesda, USA, United States 4 Royal Institute of Technology (KTH), Stockholm and Karolinska Institutet (KI), Stockholm , Sweden The basal ganglia consist of several interconnected subcortical nuclei that are supposedly involved in many motor and cognitive functions. The striatum, the input stage of the basal ganglia, is a major recipient of massive glutamatergic inputs from the cerebral cortex and thalamus. Medium spiny neurons (MSNs) dominate in the striatum (up to 95% in rodents). They are inhibitory (GABAergic) and have membrane properties that give them a high threshold for activation [1]. MSNs interact with each other through weak recurrent inhibitory synapses and with low connection probability [2]. Fast-spiking GABAergic interneurons (FSNs) can delay or prevent the emission of an action potential in MSNs [3]. FSNs receive convergent inputs from a wider range of distinct cortical regions compared to nearby MSNs, and despite the fact that they are relatively sparse elements (1-2%) it seems that they have very prominent role in shaping the output of the striatum [4]. Neuronal avalanches are a type of spontaneous activity first observed in vitro by recording local field potentials in cortical neural networks using slices of rat cortex as well as cultured networks [5]. Propagation of spontaneous activity is balanced and shows a branching parameter close to 1. In addition, the number of electrodes driven over threshold during activity is distributed approximately like a power law with an exponent of -3/2 for event sizes suggesting a critical dynamics [5]. Neural avalanches have been shown to provide: optimal information transmission [5, 6], maximal information capacity [6] and maximal dynamic range [7]. We are studying simultaneously striatal and cortical activity in vitro. Preliminary results show that neuronal avalanches in cortex induce activity clusters in striatum whose size distribution can be approximated by a steeper power law than observed in cortex. Based on this we have developed network models in order to determine the impact of different striatal neurons on the more negative exponent. In particular, we are investigating whether FS or MS neurons have any roles in shaping the striatal dynamics.

2. Spontaneous activity in electromyography – Generators and clinical correlations

In this paper different types of spontaneous activity in electromyography are presented. Possible generators of certain types of spontaneous activity (fibrillations, positive denervation potentials, fasciculations, diplets, triplets, multiplets, myokymic discharges, complex repetitive discharges, myotonic discharges, neuromyotonic discharges, cramps) across different parts of the motor units (MU) and clinical entities and syndromes in which it may be registered. There is no unique explanation for the generators of certain types of spontaneous activity in some entities. Thus, the registration of fasciculations in ALS is associated with their multifocal origin along various parts of MU. Recording of spontaneous activity may have diagnostic and prognostic value in certain neuromuscular disorders. Thus, the expression of fibrillations (1+ to 4+) is associated with the number of denervated muscle fibers in different diseases and damage of various parts of MU (motor neuron disease, neuropathy, disorders of the neuromuscular junction, myopathies). We analyzed the possible significance of various parameters of spontaneous activity in the diagnosis and prognosis of certain entities.

Differential Involvement of Projection Neurons During Emergence of Spontaneous Activity in the Developing Avian Hindbrain

To better characterize the emergence of spontaneous neuronal activity in the developing hindbrain, spontaneous activity was recorded optically from defined projection neuron populations in isolated preparations of the brain stem of the chicken embryo. Ipsilaterally projecting reticulospinal (RS) neurons and several groups of vestibuloocular (VO) neurons were labeled retrogradely with Calcium Green-1 dextran amine and spontaneous calcium transients were recorded using a charge-coupled-device camera mounted on a fluorescence microscope. Simultaneous extracellular recordings were made from one of the trigeminal motor nerves (nV) to register the occurrence of spontaneous synchronous bursts of activity. Two types of spontaneous activity were observed: synchronous events (SEs), which occurred in register with spontaneous bursts in nV once every few minutes and were tetrodotoxin (TTX) dependent, and asynchronous events (AEs), which occurred in the intervals between SEs and were TTX resistant. AEs occurred developmentally before SEs and were in general smaller and more variable in amplitude than SEs. SEs appeared at the same stage as nV bursts early on embryonic day 4, first in RS neurons and then in VO neurons. All RS neurons participated equally in SEs from the outset, whereas different subpopulations of VO neurons participated differentially, both in terms of the proportion of neurons that exhibited SEs, the fidelity with which the SEs in individual neurons followed the nV bursts, and the developmental stage at which SEs appeared and matured. The results show that spontaneous activity is expressed heterogeneously among hindbrain projection neuron populations, suggesting its differential involvement in the formation of different functional neuronal circuits.

Reactive Oxygen Species Mediate the Potentiating Effects of ATP on GABAergic Synaptic Transmission in the Immature Hippocampus

Reactive oxygen species (ROS) constitute important signaling molecules in the central nervous system. They regulate a number of different functions both under physiological conditions and under pathological conditions. Here we tested the hypothesis that in the immature hippocampus ATP, the most diffuse neurotransmitter in the brain, modulates synaptic transmission via ROS. We show that ATP, acting on metabotropic P2Y1 receptors, increased the frequency of GABA(A)-mediated spontaneous postsynaptic currents (SPSCs) in CA3 principal cells, an effect that was prevented by the antioxidant N-acetyl-cysteine or by catalase, an enzyme that breaks down H2O2. The effect of ATP on SPSCs was mimicked by H2O2 or by the pro-oxidant, Fe2+, which, through the Fentol reaction, catalyzes the conversion of H2O2 into highly reactive hydroxyl radicals. MRS-2179, a P2Y1 receptor antagonist, removed the facilitatory action of Fe2+ on SPSCs, suggesting that endogenous ATP acting on P2Y1 receptors is involved in Fe2+-induced modulation of synaptic transmission. Imaging ROS with the H2O2-sensitive dye DCF revealed that ATP induces generation of peroxide in astrocytes via activation of P2Y1 receptors coupled to intracellular calcium rise. Neither N-acetyl-cysteine nor catalase prevented Ca2+ transients induced by ATP in astrocytes. Since a single hippocampal astrocyte can contact many neurons, ATP-induced ROS signaling may control thousands of synapses. This may be crucial for information processing in the immature brain when GABAergic activity is essential for the proper wiring of the hippocampal network.

Spontaneous electromyographic activity in spinal cord lesions.

Different types of spontaneous activity may be found during electromyographic examinations in patients with spinal cord diseases. Syringomyelia and intramedullary tumor patients may show continuous motor unit activity, synchronous motor unit potentials, myokymic discharges, segmental and propriospinal myoclonus, and respiratory synkinesis. These types of discharges are less commonly encountered in other types of spinal cord lesions. It is suggested that the derangement of inhibitory mechanisms by a central spinal cord lesion may favor the appearance of abnormal spontaneous activity. An increase in the excitability of spinal motor neurons is probably the basic underlying mechanism.

Les activités spontanées en électromyographie. Intérêts pratiques

Spontaneous activities are a major semeiologic sign in electromyography. The present article deals with the different aspects recorded in practice in normal and pathological cases. There are two types of spontaneous activities, those related to motor unit hyperactivity (fasciculations and myokymia) and those related to the hyperactivity of one or more muscle fibers: fibrillations, positive sharp waves, myotonic discharges and complex repetitive discharges. In the first case the lesion is located in the axone and in the second in the membrane of the muscle fibers; All theories related to the cells’ abnormalities share a common feature: spontaneous activites result from abnormal firing of the membrane action potential of muscular fibers. This functional abnormality may results from different types of lesions within the cells’ membrane and determines the aspects of spontaneous activities. Impaired function of muscular cells’ membranes can be produced by denervation or lesion of the membrane structure itself. The latter can be multiple and linked with the membrane proteins (such as laminine or dystrophin as in AIDS diseases) or with ion channel disturbances. Multiple membrane cell alterations may produce the same kind of spontaneous activity; for instance, myotonic discharges have the same morphology in Thomsen and Steinert’s disease despite their different mechanisms and fibrillations seen in denervations and myopathies.The practical consequences are discussed and a new classification of these spontaneous activities is proposed.

Impairment Tutorial: Rating Sensory and Motor Deficits of the Upper Extremity

Abstract The three components of electrodiagnosis useful in evaluation of the peripheral nervous system and spinal cord include electromyography (EMG), electroneurography (nerve conduction studies), and somatosensory evoked potentials. EMG examination involves introduction of a special recording needle into a muscle belly. Electrical potentials located within a few millimeters of the needle are picked up by an electrode and are transmitted from the muscle to amplifiers that filter and display results visually for the electromyographer. Three types of spontaneous activity in electrical potentials are of the greatest relevance: positive sharp waves, fibrillation potentials, and fasciculations (fasciculation potentials on the EMG result from irregular firing of motor units). Electromyography can help assess the status of nerve fibers indirectly, but the integrity of large myelinated sensory and motor neurons can be evaluated directly by nerve conduction studies (NCS), also known as electroneurography. NCS can assess motor neurons, sensory neurons, or mixed nerve trunks. Sensory nerve conduction velocity can be studied in a manner analogous to motor conduction velocity: sensory fibers can be directly stimulated, and the evoked response can be measured at the wrist and elbow. Somatosensory evoked potentials occasionally are useful as an adjunct to EMG and NCS in the diagnosis of peripheral nervous system pathology. These tests also are useful when it is unclear whether an individual has a true radiculopathy.

Intracellular Recording of Spontaneous Electrical Activity in Human Urinary Bladder Smooth Muscle Strips

We studied the spontaneous electrical activity of human urinary bladder smooth muscle strips, with the eventual aim of uncovering the mechanism underlying the clinical syndrome of the unstable bladder. Intracellular microelectrodes were used to record the membrane potentials of detrusor cells in muscle bundles originating from biopsy samples. Spontaneous spike-shaped potential fluctuations were analysed automatically. The membrane potential at the start of the potential change (Vstart), amplitude, duration at 10% of the amplitude (d10%), and upstroke velocity (ΔV/Δt) were estimated and statistically analysed. The mean resting membrane potential of the detrusor strip cells was -42 mV (SD: 9 mV). Different types of spontaneous activity could be recorded. On successive impalements within one preparation, the type of activity varied from one single spike-shaped potential to extensive bu rsts and was not correlated to the resting membrane potential. There was a large variation in size and shape of the spike-shaped potentials between the biopsy samples and even within one cell. The results provide the first description of spontaneous electrical activity in human detrusor smooth muscle strips. This activity is asynchronous, which could aid to maintain a low pressure in the bladder. Most likely, this spontaneous detrusor activity is myogenic in origin.

Preferred intervals in birds and mammals: A filter response to noise?

Quasi-periodic spontaneous activity (preferred intervals, PIs) has been reported from avian primary auditory afferents. In mammals, PIs have not been reported, as yet. As the length of PIs is close to 1/characteristic frequency, it has been suggested that this type of spontaneous activity indicates particular mechanisms in avian inner ear transduction. However, the present paper shows that pigeon auditory fibres possessing preferred intervals in their spontaneous activity always belong to the most sensitive and the most sharply-tuned fibres recorded. This leads to the assumption that preferred intervals are the response of narrow-band filters to noise. This view is supported by three additional findings: (i) Near-threshold noise provokes PIs in avian fibres that show no spontaneous PIs. (ii) Similarly, PIs can also be evoked in mammalian (gerbil) auditory afferents by low level noise, (iii) Phase-locking of auditory afferents can be achieved by sound stimuli 10–20 dB below rate threshold. It is argued that no conclusions may be drawn from the presence of PIs about the nature of the underlying filter.

4-Aminopyridine-induced spreading depression episodes in immature hippocampus: Developmental and pharmacological characteristics

Spontaneous spreading depression episodes were studied in CA1 and CA3 areas of immature hippocampal slices (two to 30 days postnatally) during 4-aminopyridine (SO μM) perfusion. Spreading depression occurred in the CA3 area of 34% of all slices tested (two to 30 days postnatally). The duration and frequency of the spreading depression field potentials changed with development. In the CA3 area, their duration decreased from 169 ± 22s ( n = 17, postnatal days two to 10) to 55 ± 7s ( n = 10, postnatal days 21–30), their rate of occurrence increased from four episodes per hour ( 0.0011 ± 0.0001Hz, n = 11, postnatal days two to 10) to 6.5 episodes per hour (0.0018 ± 0.0003Hz, n = 8, postnatal days 21–30), while their amplitude remained stable (10–30 mV). Spreading depression d.c. potential shift originated closer to CA1 than CA3. Furthermore, spreading depression field potentials had greater magnitude (amplitude and duration) in CA1. Spreading depressions were reversibly blocked by the N-methyl- d-aspartate receptor antagonist 3,3-(2-carboxy-piperazine-4-yl)-propyl-1-phosphonate (CPP, 1–5 μM, n = 15), but were not affected by 6-cyano-7-nitro-quinoxaline-2,3-dione (CNQX, 2–5 μm, n = 11), which is a non- N-methyl- d-aspartate receptor antagonist. The GABA A receptor antagonist bicuculline methiodide (3–10 μM) initially favored and then blocked spreading depression in 79% of the slices tested ( n = 16). In addition, bicuculline impaired spreading depression propagation from CA1 to CA3. 4-Aminopyridine also induced the appearance of other types of spontaneous activity, such as ictal and interictal-like epileptiform discharges. The effects of 3,3-(2-carboxy-piperazine-4-yl)-propyl-1-phosphonate, 6-cyano-7-nitro-quinoxaline-2,3-dione and bicuculline on epileptiform activity were opposite to those on spreading depression. Our findings demonstrate that spreading depression can occur as early as two days postnatally and that the characteristics of this phenomenon change with maturation. These results also indicate that 4-aminopyridine-induced spreading depression episodes and epileptiform activity are mediated by the activation of different types of excitatory amino acid receptors. Finally, spreading depression is influenced by blockade of the GABA A receptor.

The effects of dark-rearing on the electrophysiology of the rat visual cortex

Our previous two studies have shown that dark-rearing affects the morphology and chemistry of adult rat primary visual cortex (area 17). In this study we demonstrate correlated physiological alterations with single unit recordings in the same preparation. Rats were raised from birth in either 14 h light/10 h dark (Lt/Dk) or in total darkness (Dk). At the age of 3 months, single units were recorded in area 17 of both groups. The cortical cells of Dk animals showed significantly more spontaneous activity during ambient lighting. The mean rate of randomly appearing spontaneous activity was greatly increased in Dk animals. Moreover, many cells in Dk animals also exhibited a particular type of spontaneous activity which occurred as ‘bursts’ of spikes, i.e. quantified groupings of fast firing spikes, separated by randomly appearing spontaneous activity. The mean number of bursts per min seen in Dk animals was also significantly more than any such activity seen in Lt/Dk animals. Visual stimuli consisted of white or dark bars moving with different orientations and directions at slow and fast speeds, and full field flashes. In response to moving stimuli, notably fewer cells were orientation- or direction tuned in dark-reared animals, and when they did respond to moving bar stimuli, the responses were of relatively longer duration. The pathologically high spontaneous activity rate, as well as lack of tuning and relatively prolonged duration of responses to moving stimuli indicate that intracortical inhibitory mechanisms are seriously compromised in both the unstimulated and stimulated states and is in agreement with our previous findings (Bakkum, B.W., Port, J.D., Cohen, R.S. and Benevento, L.A., Soc. Neursci. Abst., 15 (1989) 797) of a decreased number of synapses and GABA-containing cells in the visual cortex of the same preparation. Other evidence suggeststhat there may be a decrease in stimulus-bound excitatory drive. Significantly fewer cells in Dk animals were excited by all visual stimuli,and responses elicited by flashes had relatively longer ‘on’ latencies, relatively shorter durations, and were generally weaker. This may correlate with our finding of a significantly smaller number of perforated postsynaptic densities in the cortex of the same preparation (Bakkum, B.W., Benevento, L.A. and Cohen, R.S., J. Neurosci. Res., 23 (1991) 65–80).

Characterization of the epileptiform activity induced by magnesium-free solution in rat amygdala slices: An intracellular study

The effect of Mg 2+-free medium on neuronal activity in the basolateral nucleus of the rat amygdala slice was studied using intracellular recording techniques. Removal of Mg 2+ from perfusate resulted in the development of three types of spontaneous activity, EPSP-like, ictal-like, and interictal-like events. The ictal-like events consisted of a long-duration depolarizing potential with several recurrent interictal bursts riding on it. The tonic and clonic firing phases seen in ictal-like events closely resembled the tonic and clonic phases of seizures which may provide a new model for studying the mechanisms underlying the generation of ictal seizures. The duration of interictal-like events induced in Mg 2+-free solution is 10- to 30-fold longer than that produced by a convulsant. Two factors, a small or absent epileptiform afterhyperpolarization and a high density of NMDA receptor binding sites within the basolateral amygdala nucleus, may account for this difference.

Urinary bladder intramural neurones: an electrophysiological study utilizing a tissue culture preparation

An enzymic dispersion technique was used to free the intramural ganglia from their usual close association with the other components of the urinary bladder wall. The isolated ganglia obtained were viable and could be kept in culture for several weeks. The development of the cultures was monitored by phase-contrast microscopy and their electrophysiological properties were investigated using intracellular recording techniques. Neurones could be visually identified after 2–3 days in culture; cell groups contained from 2–50 neurones. Three types of spontaneous activity were seen: small changes in membrane potential and action potentials, and slow oscillatory conductance changes. These events were not blocked by hexamethonium but were abolished by hyperpolarizing current. Most neurones spiked without adaptation to direct stimulation; in a few cells the train of spikes was damped out. No neurones generated long afterhyperpolarizations. Indirect stimulation produced responses in the ganglia which are consistent with synaptic activity. Summation of inputs was demonstrated. These results provide evidence for local intraganglionic circuits since the ganglia or neurone groups are unequivocally extrinsically denervated. It was concluded that the intramural ganglia have the capacity to integrate preganglionic input and the question of whether or not they might mediate reflex activity is raised.

Effect of electrical stimulation of the septum on subicular neurons with different kinds of spontaneous activity in rabbits

The effect of electrical stimulation of the medial nucleus of the septum and of hippocampal area CA1 on subicular neurons with three different types of spontaneous activity (with theta-modulation, with delta-modulation and complex spikes, and with irregular single-spike activity) was studied in unanesthetized rabbits by extracellular recording of unit activity. Cells with theta-activity were found to respond in a distinctive functional manner to stimulation of the medial nucleus of the septum: Their reactivity was higher but latent periods of their responses were much shorter than those of cells with delta-activity and irregular discharges. Stability of modulation of theta-cell activity increased both during and after stimulation of the medial septal nucleus. Electrical stimulation of hippocampal area CA1, on the other hand, led to disappearance of rhythm modulation. Average response latencies of all three types of cells to stimulation of area CA1 were equal. The results indicate special properties of the septal input to subicular cells with theta-modulation.

Auditory response of saccular neurons of the catfish,Ictalurus punctatus

1. Single unit recordings were made from neurons in the saccular branch of the eighth nerve in the catfish,Ictalurus punctatus. Spontaneous activity varied from zero to 184 spikes/s among the units recorded. Non-spontaneous units and three types of spontaneous activity were observed including regular, irregular and bursting. Non-spontaneous units were most frequently encountered. 2. Iso-intensity curves were used to examine the frequency response areas of the neurons. The best frequencies of different units were continuously distributed from below 160 Hz to over 1,250 Hz, with the most abundant units exhibiting best frequencies below 250 Hz. 3. Units having different best frequencies were, to a limited extent, tonotopically distributed within the saccular nerve, with low frequency units located more dorsally in the nerve than the high frequency units. 4. Phase locking was quantitatively assessed using a coefficient of synchronization (R). For each unit, the degree of phase locking varied with frequency and intensity of the stimulus. At any one intensity, the highest degree of phase locking was generally observed at the unit's best frequency. Increases in stimulus intensity resulted in enhanced phase locking ability up to a maximum value. The maximum R value was lower for units having best frequencies above 630 Hz, suggesting that these units were less capable of phase locking than lower frequency units.

Effect of destruction of afferent inputs on spontaneous unit activity and character of neuronal interconnection in the rat neostriatum

The effect of destruction of afferent inputs on relations between types of spontaneous unit activity, its mean frequency, the distribution of minimal and maximal intervals, and the character of neuronal interconnection in the neostriatum was studied in acute experiments on rats immobilized with D-tubocurarine. In addition, spontaneous activity derived from neurons in slices of rat neostriatum was analyzed. Spontaneous activity of grouped type was not observed, and no positive symmetrical maxima in the zero region were present on graphs of cross-correlation function. The results of the investigation showed that the grouped type of spontaneous activity is determined by activity of the cortical input whereas activity of the thalamic input has a tendency to prevent the development of this type of neostriatal unit activity. Activation of the cortical input also was shown to be probably responsible for the presence of a positive symmetrical peak on the cross-correlation function graph for neurons with the grouped type of spontaneous activity.