Effects of substantia nigra stimulation on high- and low-threshold response in reticular neurons

The mantis shrimp Squilla mantis shows a graded series of avoidance/escape responses to visual and mechanical (vibration and touch) rostral stimuli. A low-threshold response is mediated by the simultaneous protraction of the thoracic walking legs and abdominal swimmerets and telson, producing a backwards ‘lurch’ or jump that can displace the animal by up to one-third of its body length, but leaves it facing in the same direction. A stronger response starts with similar limb protraction, but is followed by partial abdominal flexion. The maximal response also consists of limb protraction followed by abdominal flexion, but in this case the abdominal flexion is sufficiently vigorous to pull the animal into a tight vertical loop, which leaves it inverted and facing away from the stimulus. The animal then swims forward (away from the stimulus) and rights itself by executing a half-roll. A bilaterally paired, large-diameter, rapidly conducting axon in the dorsal region of the ventral nerve excites swimmeret protractor motoneurons in several ganglia and is likely to be the driver neuron for the limb-protraction response. The same neuron also excites unidentified abdominal trunk motoneurons, but less reliably. The escape response is a key feature of the malacostracan caridoid facies, and we provide the first detailed description of this response in a group that diverged early in malacostracan evolution. We show that the components of the escape response contrast strongly with those of the full caridoid reaction, and we provide physiological and behavioural evidence for the biological plausibility of a limb-before-tail thesis for the evolution of the escape response.

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A low threshold calcium spike mediates firing pattern alterations in pontine reticular neurons

Science ◽

10.1126/science.3775364 ◽

1986 ◽

Vol 234 (4777) ◽

pp. 738-740 ◽

Cited By ~ 37

Author(s):

R. Greene ◽

H. Haas ◽

R. McCarley

Keyword(s):

Firing Pattern ◽

Reticular Neurons ◽

Low Threshold

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The initiation of bursts in thalamic neurons and the cortical control of thalamic sensitivity

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2002.1154 ◽

2002 ◽

Vol 357 (1428) ◽

pp. 1649-1657 ◽

Cited By ~ 38

Author(s):

Alain Destexhe ◽

Terrence J. Sejnowski

Keyword(s):

Computational Models ◽

Distribution Patterns ◽

Cell Types ◽

Thalamic Neurons ◽

Thalamic Relay ◽

Reticular Neurons ◽

Low Threshold ◽

Degree Of Convergence ◽

High Degree ◽

Kinetics Of

Thalamic neurons generate high–frequency bursts of action potentials when a low–threshold (T–type) calcium current, located in soma and dendrites, becomes activated. Computational models were used to investigate the bursting properties of thalamic relay and reticular neurons. These two types of thalamic cells differ fundamentally in their ability to generate bursts following either excitatory or inhibitory events. Bursts generated with excitatory inputs in relay cells required a high degree of convergence from excitatory inputs, whereas moderate excitation drove burst discharges in reticular neurons from hyperpolarized levels. The opposite holds for inhibitory rebound bursts, which are more difficult to evoke in reticular neurons than in relay cells. The differences between the reticular neurons and thalamocortical neurons were due to different kinetics of the T–current, different electrotonic properties and different distribution patterns of the T–current in the two cell types. These properties enable the cortex to control the sensitivity of the thalamus to inputs and are also important for understanding states such as absence seizures.

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Arrhythmic Firing in Dopamine Neurons of Rat Substantia Nigra Evoked by Activation of Subthalamic Neurons

Journal of Neurophysiology ◽

10.1152/jn.1999.82.3.1632 ◽

1999 ◽

Vol 82 (3) ◽

pp. 1632-1637 ◽

Cited By ~ 12

Author(s):

Youngnam Kang ◽

Takahiro Futami

Keyword(s):

Substantia Nigra ◽

Dopaminergic Neurons ◽

Interspike Interval ◽

Dopamine Neurons ◽

Low Threshold ◽

Rhythmic Firing ◽

Subthalamic Neurons ◽

Synaptic Influence ◽

Rat Substantia Nigra

Intracellular recordings were made from dopaminergic neurons of the rat substantia nigra compacta (SNc) in in vitro slice preparations to study the synaptic influence from the subthalamic nucleus (STh). After microstimulation of STh, monosynaptic excitatory postsynaptic potentials (EPSPs) were produced in dopaminergic neurons. STh-induced EPSPs were composed of 6-cyano-7-nitroquinoxalene-2,3-dione- and 2-amino-5-phosphonovaleric acid-sensitive components. Subthreshold EPSPs evoked by STh stimulation could differentially trigger pacemaker-like slow depolarization (PLSD) and low-threshold Ca2+ spike (LTS) depending on the level of baseline membrane potentials. When a subthreshold EPSP was evoked by STh stimulation during rhythmic firing, the STh-induced EPSP could shift or elevate PLSD to a more depolarized level, resulting in generation of a spike at an earlier arrhythmic timing to restart the rhythmic firing. The interspike interval after the arrhythmic spike remained almost unchanged. In contrast, when a suprathreshold EPSP for evoking spikes was produced by STh stimulation during rhythmic firing, the STh-induced spike was just interposed between two spontaneous spikes the interspike interval of which was almost the same as those seen during the preceding rhythmic firing. This ectopically induced spike did not disturb or reset rhythmic firing. It was concluded that SNc dopaminergic neurons receive monosynaptic glutamatergic inputs from STh, and subthreshold and suprathreshold EPSPs evoked by STh stimulations can induce two types of arrhythmic firing in SNc dopaminergic neurons, similar to arrhythmic occurrences of the QRS complex seen in the electrocardiogram of the atrial and ventricular arrhythmias, respectively. The former arrhythmic firing may play a crucial role in desynchronization of dopaminergic neurons.

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Association between the low threshold calcium spike and activation of NMDA receptors in guinea-pig substantia nigra pars compacta neurons

European Journal of Neuroscience ◽

10.1046/j.1460-9568.1998.00210.x ◽

1998 ◽

Vol 10 (6) ◽

pp. 2009-2015 ◽

Cited By ~ 5

Author(s):

Christelle L. M. Bon ◽

Ole Paulsen ◽

Susan A. Greenfield

Keyword(s):

Substantia Nigra ◽

Guinea Pig ◽

Nmda Receptors ◽

Substantia Nigra Pars Compacta ◽

Low Threshold

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Low-Threshold Ca2+ Current Amplifies Distal Dendritic Signaling in Thalamic Reticular Neurons

Journal of Neuroscience ◽

10.1523/jneurosci.3636-10.2010 ◽

2010 ◽

Vol 30 (46) ◽

pp. 15419-15429 ◽

Cited By ~ 52

Author(s):

S. R. Crandall ◽

G. Govindaiah ◽

C. L. Cox

Keyword(s):

Reticular Neurons ◽

Low Threshold

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Immunocytochemical methodology for the localization of neuronal antigens at the ultrastructural level

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100161941 ◽

1990 ◽

Vol 48 (3) ◽

pp. 876-877

Author(s):

Jorge Pecci Saavedra ◽

Mark Connaughton ◽

Juan José López ◽

Alicia Brusco

Keyword(s):

Spinal Cord ◽

Substantia Nigra ◽

Polyclonal Antibodies ◽

Ultrastructural Level ◽

Point Of View ◽

Nerve Tissue ◽

Tissue Fixation ◽

Optimal Conditions ◽

Interpeduncular Nucleus ◽

Technical Point

The use of antibodies as labels for the localization of specific molecules in the nervous systan has been extensively applied in recent years. Both monoand polyclonal antibodies or antisera have been employed. The knowledge of the organization of neuronal connectivities, gliovascular relationships, glioneuronal relationships and other features of nerve tissue has greatly increased.A number of areas of the nervous systan have been analyzed in our laboratory, including the nuclei of the raphe system, the reticular formation, interpeduncular nucleus, substantia nigra, caudate nucleus, putamen, pallidum, spinal cord, pineal gland and others.From a technical point of view, a number of variables needed to be taken into account in order to obtain reliable and reproducible results. The design of the optimal conditions of tissue fixation, embedding, sectioning, dilution of antibodies, and adaptation of Sternberger PAP technique were sane of the parameters taken into account to optimize the results. It is critical that each step of the technique be defined for each particular case.

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