Some response characteristics of cells of the magnocellular division of the medial geniculate body of the cat

1969 ◽  
Vol 47 (10) ◽  
pp. 881-888 ◽  
Author(s):  
James A. Love ◽  
John W. Scott
Keyword(s):  
Medial Geniculate Body ◽  
Posterior Region ◽  
Single Units ◽  
Anterior Region ◽  
Sodium Pentobarbital ◽  
Experimental Conditions ◽  
Extracellular Recordings ◽  
Response Characteristics ◽  
Medial Geniculate ◽  
Somatosensory Stimuli

Extracellular recordings were made from single units in the magnocellular division of the medial geniculate body of the cat. The stimuli most frequently used were auditory clicks repeated at varying rates and intensities. Somatosensory stimuli were also used to reveal the presence of polysensory units. The response characteristics for most of the cells of the magnocellular division differed from those of the principal division under similar experimental conditions. A difference was noted between the responses obtained from animals which were anesthetized with chloralose and those anesthetized with sodium pentobarbital. It is suggested that the magnocellular division of the medial geniculate body may be divided into two regions, an anterior region which is primarily somatosensory in function and a posterior region which is primarily auditory in function.

scholarly journals Synaptic Properties of Thalamic Input to Layers 2/3 and 4 of Primary Somatosensory and Auditory Cortices

2011 ◽  
Vol 105 (1) ◽  
pp. 279-292 ◽  
Author(s):  
Angela N. Viaene ◽  
Iraklis Petrof ◽  
S. Murray Sherman
Keyword(s):  
Medial Geniculate Body ◽  
Postsynaptic Neuron ◽  
Paired Pulse ◽  
Response Characteristics ◽  
Medial Nucleus ◽  
Thalamic Stimulation ◽  
Thalamocortical Projections ◽  
Class 1 ◽  
Medial Geniculate ◽  
Posterior Medial Nucleus

We studied the synaptic profile of thalamic inputs to cells in layers 2/3 and 4 of primary somatosensory (S1) and auditory (A1) cortices using thalamocortical slices from mice age postnatal days 10–18. Stimulation of the ventral posterior medial nucleus (VPM) or ventral division of the medial geniculate body (MGBv) resulted in two distinct classes of responses. The response of all layer 4 cells and a minority of layers 2/3 cells to thalamic stimulation was Class 1, including paired-pulse depression, all-or-none responses, and the absence of a metabotropic component. On the other hand, the majority of neurons in layers 2/3 showed a markedly different, Class 2 response to thalamic stimulation: paired-pulse facilitation, graded responses, and a metabotropic component. The Class 1 and Class 2 response characteristics have been previously seen in inputs to thalamus and have been described as drivers and modulators, respectively. Driver input constitutes a main information bearing pathway and determines the receptive field properties of the postsynaptic neuron, whereas modulator input influences the response properties of the postsynaptic neuron but is not a primary information bearing input. Because these thalamocortical projections have comparable properties to the drivers and modulators in thalamus, we suggest that a driver/modulator distinction may also apply to thalamocortical projections. In addition, our data suggest that thalamus is likely to be more than just a simple relay of information and may be directly modulating cortex.

Extent and properties of the regeneration field in the larval legs of cockroaches (Leucophaea maderae)

Development ◽  
1974 ◽  
Vol 31 (3) ◽  
pp. 557-572
Author(s):  
Horst Bohn
Keyword(s):  
Anterior Part ◽  
Posterior Region ◽  
Anterior Region ◽  
Posterior Border ◽  
Anterior Border ◽  
Experimental Conditions ◽  
Leucophaea Maderae ◽  
Reversed Polarity ◽  
Anterior Posterior

Extirpation experiments have been performed on the larvae of cockroaches (Leucophaea maderae) to determine the extent and properties of the regeneration field of the legs of these insects. The distal segments, including the coxa, may all be removed without loss of regenerative capability; but regenerative capability eventually disappears if more proximal parts are removed. There are two regions adjoining the coxa anteriorly and posteriorly which are both important for leg regeneration. The anterior region consists of the sclerotized basal parts of the leg mainly formed by the trochantin and the praecoxa. The posterior region is an unsclerotized membranous area extending from the posterior border of the coxa to the anterior border of the next segment. This membrane is called ‘leg-inducing membrane’. If only one of these two regions is present, no leg regeneration will occur. The interaction of both parts is necessary to allow the formation of a complete leg. An extra leg with reversed anterior–posterior polarity is formed when the ‘leg-inducing membrane’ of one segment is brought into contact with the sclerites of the following segment after extirpation of the membranous area which normally separates them. This membranous area, which represents the most anterior part of a segment, is called ‘sclerite-inducing membrane’, for if the basal sclerites or part of them are combined with this membrane only sclerites are formed, either in normal or reversed polarity depending on the experimental conditions.

Tone-burst response patterns of single units in the cat medial geniculate body

1969 ◽  
Vol 16 (1) ◽  
pp. 149-164 ◽  
Author(s):  
C.W. Dunlop ◽  
D.J. Itzkowic ◽  
L.M. Aitkin
Keyword(s):  
Medial Geniculate Body ◽  
Tone Burst ◽  
Single Units ◽  
Response Patterns ◽  
Medial Geniculate

scholarly journals Noise-induced neurophysiological alterations in the rat medial geniculate body and thalamocortical desynchronization by deep brain stimulation

2021 ◽  
Author(s):  
Gusta van Zwieten ◽  
Mark J. Roberts ◽  
Frédéric LVW Schaper ◽  
Jasper V Smit ◽  
Yasin Temel ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Brain Stimulation ◽  
High Frequency ◽  
Noise Exposure ◽  
Medial Geniculate Body ◽  
Single Units ◽  
Control Group ◽  
Sprague Dawley ◽  
Medial Geniculate ◽  
Deep Brain

The thalamic medial geniculate body (MGB) is uniquely positioned within the neural tinnitus networks. Deep brain stimulation (DBS) of the MGB has been proposed as a possible novel treatment for tinnitus, yet mechanisms remain elusive. The aim of this study was to characterize neurophysiologic hallmarks in the MGB after noise-exposure and to assess the neurophysiological effects of electrical stimulation of the MGB. Fourteen male Sprague Dawley rats were included. Nine subjects were unilaterally exposed to a 16 kHz octave-band noise at 115 dB for 90 minutes, five received sham exposure. Single units were recorded from the contralateral MGB where spontaneous firing, coefficient of variation, response type, rate-level functions and thresholds were determined. Local field potentials and electroencephalographical (EEG) recordings were performed before and after high frequency DBS of the MGB. Thalamocortical synchronization and power were analyzed. In total, 214 single units were identified (n = 145 in noise-exposed group, n = 69 in control group). After noise-exposure, fast-responding neurons become less- or non-responsive without change to their spontaneous rate, while sustained and suppressed type neurons exhibit enhanced spontaneous activity without change to their stimulus driven activity. MGB DBS suppressed thalamocortical synchronization in the beta and gamma bands, supporting suppression of thalamocortical synchronization as an underlying mechanism of tinnitus suppression by high frequency DBS. These findings contribute to our understanding of the neurophysiologic consequences of noise-exposure and the mechanism of potential DBS therapy for tinnitus.

Discharge properties of single units in auditory part of reticular nucleus of thalamus in cat

1990 ◽  
Vol 63 (5) ◽  
pp. 1010-1021 ◽  
Author(s):  
G. M. Simm ◽  
F. de Ribaupierre ◽  
Y. de Ribaupierre ◽  
E. M. Rouiller
Keyword(s):  
Spontaneous Activity ◽  
Frequency Tuning ◽  
Anterior Part ◽  
Medial Geniculate Body ◽  
Acoustic Stimulation ◽  
Single Units ◽  
Reticular Nucleus ◽  
Median Response ◽  
Medial Geniculate ◽  
Intensity Functions

1. Extracellular recordings from 153 single units were obtained in the auditory part of the reticular nucleus (RE) of the thalamus of anesthetized cats. 2. In absence of acoustic stimulation, the majority of RE units (75%) had a spontaneous activity characterized by bursts of spikes lasting over 30 ms, alternating with isolated discharges; in contrast, only 30% of units in the medial geniculate body (MGB) showed these long bursts during spontaneous activity. 3. For a majority of RE units (65%), activity evoked by noise bursts consisted in complex response patterns with multiple excitatory and/or inhibitory components. For this stimulus, most units (79%) showed nonmonotonic rate-intensity functions, and median response latency to the first excitatory component was 16 ms, which is slightly longer than that obtained in the anterior part of the ventral division of the MGB for the same conditions. 4. Frequency tuning to pure tones in RE was usually broad: the median value of the width of response ranges was five octaves in RE, as compared to two octaves in the ventral division of the MGB and three octaves in the medial division of the MGB. Responses to tones were complex, usually characterized by frequent changes of response pattern with frequency. No preferential arrangement of units as a function of their best frequency was found along a rostrocaudal or a dorsolateral to ventromedial axis. 5. The present study demonstrates that units in the auditory part of RE have discharge properties clearly different from the main auditory thalamic nucleus, the MGB.

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