Corticofugal Modulation of Tactile Responses of Neurons in the Spinal Trigeminal Nucleus

2011 ◽  
pp. 1-19
Author(s):  
Eduardo Malmierca ◽  
Nazareth P. Castellanos ◽  
Valeri A. Makarov ◽  
Angel Nuñez
Keyword(s):  
Tactile Stimulation ◽  
Early Stage ◽  
Temporal Structure ◽  
Spike Timing ◽  
Mathematical Tool ◽  
Spinal Trigeminal Nucleus ◽  
Trigeminal Nucleus ◽  
Simultaneous Application ◽  
Trigeminal Neurons ◽  
Attentional Filter

It is well know the temporal structure of spike discharges is crucial to elicit different types of neuronal plasticity. Also, precise and reproducible spike timing is one of the alternatives of the sensory stimulus encoding. This chapter studies a new mathematical analysis of the temporal structure of neuronal responses during tactile stimulation of the spinal trigeminal nucleus. We have applied the coherence analysis and the wavelet based approach for quantification of the functional stimulus - neural response coupling. We apply this mathematical tool to analyze the decrease of tactile responses of trigeminal neurons during the simultaneous application of a novel tactile stimulation outside of the neuronal receptive field (sensory-interference). These data suggest the existence of an attentional filter at this early stage of sensory processing.

Corticofugal Modulation of the Tactile Response Coherence of Projecting Neurons in the Gracilis Nucleus

2007 ◽  
Vol 98 (5) ◽  
pp. 2537-2549 ◽  
Author(s):  
Nazareth P. Castellanos ◽  
Eduardo Malmierca ◽  
Angel Nuñez ◽  
Valeri A. Makarov
Keyword(s):  
Electrical Stimulation ◽  
Tactile Stimulation ◽  
Spectral Power ◽  
Temporal Structure ◽  
Neural Response ◽  
Spike Timing ◽  
Sensory Stimulus ◽  
Functional Coupling ◽  
Tactile Response ◽  
Stimulation Of

Precise and reproducible spike timing is one of the alternatives of the sensory stimulus encoding. We test coherence (repeatability) of the response patterns elicited in projecting gracile neurons by tactile stimulation and its modulation provoked by electrical stimulation of the corticofugal feedback from the somatosensory (SI) cortex. To gain the temporal structure we adopt the wavelet-based approach for quantification of the functional stimulus–neural response coupling. We show that the spontaneous firing patterns (when they exist) are essentially random. Tactile stimulation of the neuron receptive field strongly increases the spectral power in the stimulus and 5- to 15-Hz frequency bands. However, the functional coupling (coherence) between the sensory stimulus and the neural response exhibits ultraslow oscillation (0.07 Hz). During this oscillation the stimulus coherence can temporarily fall below the statistically significant level, i.e., the functional stimulus–response coupling may be temporarily lost for a single neuron. We further demonstrate that electrical stimulation of the SI cortex increases the stimulus coherence for about 60% of cells. We find no significant correlation between the increment of the firing rate and the stimulus coherence, but we show that there is a positive correlation with the amplitude of the peristimulus time histogram. The latter argues that the observed facilitation of the neural response by the corticofugal pathway, at least in part, may be mediated through an appropriate ordering of the stimulus-evoked firing pattern, and the coherence enhancement is more relevant in gracilis nucleus than an increase of the number of spikes elicited by the tactile stimulus.

scholarly journals Mechanisms of Peripheral and Central Pain Sensitization: Focus on Ocular Pain

2021 ◽  
Vol 12 ◽  
Author(s):  
Giulia Puja ◽  
Balazs Sonkodi ◽  
Rita Bardoni
Keyword(s):  
Central Pain ◽  
Spinal Trigeminal Nucleus ◽  
Trigeminal Nucleus ◽  
Ocular Pain ◽  
Cellular Mechanisms ◽  
New Techniques ◽  
Functional Changes ◽  
Corneal Inflammation ◽  
Pain Sensitization ◽  
Trigeminal Nerves

Persistent ocular pain caused by corneal inflammation and/or nerve injury is accompanied by significant alterations along the pain axis. Both primary sensory neurons in the trigeminal nerves and secondary neurons in the spinal trigeminal nucleus are subjected to profound morphological and functional changes, leading to peripheral and central pain sensitization. Several studies using animal models of inflammatory and neuropathic ocular pain have provided insight about the mechanisms involved in these maladaptive changes. Recently, the advent of new techniques such as optogenetics or genetic neuronal labelling has allowed the investigation of identified circuits involved in nociception, both at the spinal and trigeminal level. In this review, we will describe some of the mechanisms that contribute to the perception of ocular pain at the periphery and at the spinal trigeminal nucleus. Recent advances in the discovery of molecular and cellular mechanisms contributing to peripheral and central pain sensitization of the trigeminal pathways will be also presented.

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