scholarly journals Encoding of Stimulus Frequency and Sensor Motion in the Posterior Medial Thalamic Nucleus

2008 ◽  
Vol 100 (2) ◽  
pp. 681-689 ◽  
Author(s):  
Radi Masri ◽  
Tatiana Bezdudnaya ◽  
Jason C. Trageser ◽  
Asaf Keller
Keyword(s):  
Barrel Cortex ◽  
Stimulus Frequency ◽  
Response Duration ◽  
Stimulation Frequency ◽  
Response Latencies ◽  
Medial Nucleus ◽  
Anesthetized Rats ◽  
Reticular Activating System ◽  
Parallel Streams ◽  
Posterior Medial Nucleus

In all sensory systems, information is processed along several parallel streams. In the vibrissa-to-barrel cortex system, these include the lemniscal system and the lesser-known paralemniscal system. The posterior medial nucleus (POm) is the thalamic structure associated with the latter pathway. Previous studies suggested that POm response latencies are positively correlated with stimulation frequency and negatively correlated with response duration, providing a basis for a phase locked loop-temporal decoding of stimulus frequency. We tested this hypothesis by analyzing response latencies of POm neurons, in both awake and anesthetized rats, to vibrissae deflections at frequencies between 0.3 and 11 Hz. We found no significant, systematic correlation between stimulation frequency and the latency or duration of POm responses. We obtained similar findings from recording in awake rats, in rats under different anesthetics, and in anesthetized rats in which the reticular activating system was stimulated. These findings suggest that stimulus frequency is not reliably reflected in response latency of POm neurons. We also tested the hypothesis that POm neurons respond preferentially to sensor motion, that is, they respond to whisking in air, without contacts. We recorded from awake, head-restrained rats while monitoring vibrissae movements. All POm neurons responded to passive whisker deflections, but none responded to noncontact whisking. Thus like their counterparts in the trigeminal ganglion, POm neurons may not reliably encode whisking kinematics. These observations suggest that POm neurons might not faithfully encode vibrissae inputs to provide reliable information on vibrissae movements or contacts.

scholarly journals Responses of thalamic neurons to itch- and pain-producing stimuli in rats

2018 ◽  
Vol 120 (3) ◽  
pp. 1119-1134 ◽  
Author(s):  
Brett Lipshetz ◽  
Sergey G. Khasabov ◽  
Hai Truong ◽  
Theoden I. Netoff ◽  
Donald A. Simone ◽  
...  
Keyword(s):  
Single Unit ◽  
Electrophysiological Study ◽  
Receptive Fields ◽  
The Body ◽  
Cell Column ◽  
Thalamic Neurons ◽  
Medial Nucleus ◽  
Anesthetized Rats ◽  
Transmission Of Information ◽  
Posterior Medial Nucleus

Understanding of processing and transmission of information related to itch and pain in the thalamus is incomplete. In fact, no single unit studies of pruriceptive transmission in the thalamus have yet appeared. In urethane-anesthetized rats, we examined responses of 66 thalamic neurons to itch- and pain- inducing stimuli including chloroquine, serotonin, β-alanine, histamine, and capsaicin. Eighty percent of all cells were activated by intradermal injections of one or more pruritogens. Forty percent of tested neurons responded to injection of three, four, or even five agents. Almost half of the examined neurons had mechanically defined receptive fields that extended onto distant areas of the body. Pruriceptive neurons were located within what appeared to be a continuous cell column extending from the posterior triangular nucleus (PoT) caudally to the ventral posterior medial nucleus (VPM) rostrally. All neurons tested within PoT were found to be pruriceptive. In addition, neurons in this nucleus responded at higher frequencies than did those in VPM, an indication that PoT might prove to be a particularly interesting region for additional studies of itch transmission. NEW & NOTEWORTHY Processing of information related to itch within in the thalamus is not well understood, We show in this, the first single-unit electrophysiological study of responses of thalamic neurons to pruritogens, that itch-responsive neurons are concentrated in two nuclei within the rat thalamus, the posterior triangular, and the ventral posterior medial nuclei.

scholarly journals Synapses from the high-order thalamic nucleus and motor cortex are co-clustered in the distal tuft dendrites of the mouse somatosensory cortex

2020 ◽  
Author(s):  
Nari Kim ◽  
Sangkyu Bahn ◽  
Joon Ho Choi ◽  
Jinseop S. Kim ◽  
Jong-Cheol Rah
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Barrel Cortex ◽  
Essential Information ◽  
Medial Nucleus ◽  
Array Tomography ◽  
Posterior Medial Nucleus ◽  
Dendritic Branches ◽  
Insight Into

ABSTRACTThe posterior medial nucleus of the thalamus (POm) and vibrissal primary motor cortex (vM1) convey essential information to the barrel cortex (S1BF) regarding whisker position and movement. Therefore, understanding the relative spatial relationships of these two inputs is critical prerequisites to acquire insight into how S1 synthesizes information to interpret the location of an object. Using array tomography, we identified the locations of synapses from vM1 and POm on distal tuft dendrites of L5 pyramidal neurons. We found that synapses from vM1 and POm are spatially clustered on the same set of dendrites with unusually high density. Furthermore, the clusters of vM1 and POm synapses colocalize each other. These findings suggest that synaptic clusters, but not dendritic branches, act as functional units and cooperatively contribute to nonlinear dendritic responses.

scholarly journals Organization and somatotopy of corticothalamic projections from L5B in mouse barrel cortex

2017 ◽  
Vol 114 (33) ◽  
pp. 8853-8858 ◽  
Author(s):  
Anton Sumser ◽  
Rebecca A. Mease ◽  
Bert Sakmann ◽  
Alexander Groh
Keyword(s):  
Spatial Organization ◽  
Barrel Cortex ◽  
Cortical Layer ◽  
Three Dimensions ◽  
Zona Incerta ◽  
Medial Nucleus ◽  
Posterior Group ◽  
Posterior Medial Nucleus ◽  
Whisker Map ◽  
Corticothalamic Projections

Neurons in cortical layer 5B (L5B) connect the cortex to numerous subcortical areas. Possibly the best-studied L5B cortico–subcortical connection is that between L5B neurons in the rodent barrel cortex (BC) and the posterior medial nucleus of the thalamus (POm). However, the spatial organization of L5B giant boutons in the POm and other subcortical targets is not known, and therefore it is unclear if this descending pathway retains somatotopy, i.e., body map organization, a hallmark of the ascending somatosensory pathway. We investigated the organization of the descending L5B pathway from the BC by dual-color anterograde labeling. We reconstructed and quantified the bouton clouds originating from adjacent L5B columns in the BC in three dimensions. L5B cells target six nuclei in the anterior midbrain and thalamus, including the posterior thalamus, the zona incerta, and the anterior pretectum. The L5B subcortical innervation is target specific in terms of bouton numbers, density, and projection volume. Common to all target nuclei investigated here is the maintenance of projection topology from different barrel columns in the BC, albeit with target-specific precision. We estimated low cortico–subcortical convergence and divergence, demonstrating that the L5B corticothalamic pathway is sparse and highly parallelized. Finally, the spatial organization of boutons and whisker map organization revealed the subdivision of the posterior group of the thalamus into four subnuclei (anterior, lateral, medial, and posterior). In conclusion, corticofugal L5B neurons establish a widespread cortico–subcortical network via sparse and somatotopically organized parallel pathways.

scholarly journals Integration of signals from different cortical areas in higher order thalamic neurons

2021 ◽  
Vol 118 (30) ◽  
pp. e2104137118
Author(s):  
Vandana Sampathkumar ◽  
Andrew Miller-Hansen ◽  
S. Murray Sherman ◽  
Narayanan Kasthuri
Keyword(s):  
Higher Order ◽  
Cortical Layer ◽  
Thalamic Neurons ◽  
Cortical Areas ◽  
Medial Nucleus ◽  
Afferent Information ◽  
Posterior Medial Nucleus ◽  
Depth And Complexity ◽  
Genetic Labeling

Higher order thalamic neurons receive driving inputs from cortical layer 5 and project back to the cortex, reflecting a transthalamic route for corticocortical communication. To determine whether or not individual neurons integrate signals from different cortical populations, we combined electron microscopy “connectomics” in mice with genetic labeling to disambiguate layer 5 synapses from somatosensory and motor cortices to the higher order thalamic posterior medial nucleus. A significant convergence of these inputs was found on 19 of 33 reconstructed thalamic cells, and as a population, the layer 5 synapses were larger and located more proximally on dendrites than were unlabeled synapses. Thus, many or most of these thalamic neurons do not simply relay afferent information but instead integrate signals as disparate in this case as those emanating from sensory and motor cortices. These findings add further depth and complexity to the role of the higher order thalamus in overall cortical functioning.

scholarly journals Target-specific M1 inputs to infragranular S1 pyramidal neurons

2016 ◽  
Vol 116 (3) ◽  
pp. 1261-1274 ◽  
Author(s):  
Amanda K. Kinnischtzke ◽  
Erika E. Fanselow ◽  
Daniel J. Simons
Keyword(s):  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Projection Neurons ◽  
Cell Type ◽  
Intrinsic Properties ◽  
Subcortical Structures ◽  
Medial Nucleus ◽  
Cell Type Specific ◽  
Posterior Medial Nucleus

The functional role of input from the primary motor cortex (M1) to primary somatosensory cortex (S1) is unclear; one key to understanding this pathway may lie in elucidating the cell-type specific microcircuits that connect S1 and M1. Recently, we discovered that a subset of pyramidal neurons in the infragranular layers of S1 receive especially strong input from M1 (Kinnischtzke AK, Simons DJ, Fanselow EE. Cereb Cortex 24: 2237–2248, 2014), suggesting that M1 may affect specific classes of pyramidal neurons differently. Here, using combined optogenetic and retrograde labeling approaches in the mouse, we examined the strengths of M1 inputs to five classes of infragranular S1 neurons categorized by their projections to particular cortical and subcortical targets. We found that the magnitude of M1 synaptic input to S1 pyramidal neurons varies greatly depending on the projection target of the postsynaptic neuron. Of the populations examined, M1-projecting corticocortical neurons in L6 received the strongest M1 inputs, whereas ventral posterior medial nucleus-projecting corticothalamic neurons, also located in L6, received the weakest. Each population also possessed distinct intrinsic properties. The results suggest that M1 differentially engages specific classes of S1 projection neurons, thereby regulating the motor-related influence S1 exerts over subcortical structures.

Influence of stimulation frequency on [Na+]i and contractile function in Langendorff-perfused rat heart

1997 ◽  
Vol 273 (3) ◽  
pp. H1246-H1254 ◽  
Author(s):  
L. S. Maier ◽  
B. Pieske ◽  
D. G. Allen
Keyword(s):  
Rat Heart ◽  
Contractile Function ◽  
Stimulus Frequency ◽  
Calibration Procedure ◽  
Stimulation Frequency ◽  
Pressure Amplitude ◽  
Rat Hearts ◽  
Perfused Rat Hearts ◽  
Frequency Relationship ◽  
Triton X

To study the relationship between stimulation frequency and intracellular Na+ concentration ([Na+]i), Langendorff-perfused rat hearts were loaded with the Na(+)-sensitive dye sodium-binding benzofuran isophthalate (SBFI). An intracellular calibration procedure allowed SBFI fluorescence to be transformed into [Na+]i. Compartmentation of SBFI was evaluated by permeabilizing sarcolemmal membranes with saponin and subcellular compartments with Triton X-100. Most of the indicator was located in the myoplasm (69%). When stimulation frequency was increased from 0 to 6 Hz, [Na+]i increased from 3.0 to 7.9 mM, whereas pressure amplitude (PA) declined to 49% of the maximum recorded at 2 Hz. Blocking sarcoplasmic reticulum (SR) Ca2+ uptake with 2,5-di(tert-butyl)-1,4-benzohydroquinone (TBQ; 10 microM) at 2 Hz increased [Na+]i from 4.9 to 8.4 mM and decreased PA by 70%. Raising stimulation frequency then resulted in a further increase in [Na+]i and decline in PA. In conclusion, these data indicate that the rat heart is characterized by a negative pressure-frequency relationship associated with increasing [Na+]i at higher heart rates. After inhibition of SR Ca2+ uptake, [Na+]i further increases, whereas PA declines with increasing stimulus frequency. It is suggested that part of the rise of [Na+]i with stimulus frequency and TBQ may be associated with increased Ca2+ extrusion and Na+ influx on the Na+/Ca2+ exchange system.

scholarly journals High-order thalamic inputs to primary somatosensory cortex are stronger and longer lasting than cortical inputs

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Wanying Zhang ◽  
Randy M Bruno
Keyword(s):  
Somatosensory Cortex ◽  
Primary Motor Cortex ◽  
Pyramidal Neurons ◽  
Sensory Stimulation ◽  
Primary Somatosensory Cortex ◽  
Specific Substrate ◽  
Medial Nucleus ◽  
Posterior Medial Nucleus ◽  
Cortical Inputs

Layer (L) 2/3 pyramidal neurons in the primary somatosensory cortex (S1) are sparsely active, spontaneously and during sensory stimulation. Long-range inputs from higher areas may gate L2/3 activity. We investigated their in vivo impact by expressing channelrhodopsin in three main sources of feedback to rat S1: primary motor cortex, secondary somatosensory cortex, and secondary somatosensory thalamic nucleus (the posterior medial nucleus, POm). Inputs from cortical areas were relatively weak. POm, however, more robustly depolarized L2/3 cells and, when paired with peripheral stimulation, evoked action potentials. POm triggered not only a stronger fast-onset depolarization but also a delayed all-or-none persistent depolarization, lasting up to 1 s and exhibiting alpha/beta-range oscillations. Inactivating POm somata abolished persistent but not initial depolarization, indicating a recurrent circuit mechanism. We conclude that secondary thalamus can enhance L2/3 responsiveness over long periods. Such timescales could provide a potential modality-specific substrate for attention, working memory, and plasticity.

Active tactile exploration influences the functional maturation of the somatosensory system

1996 ◽  
Vol 75 (5) ◽  
pp. 2192-2196 ◽  
Author(s):  
M. A. Nicolelis ◽  
L. M. De Oliveira ◽  
R. C. Lin ◽  
J. K. Chapin
Keyword(s):  
Facial Nerve ◽  
Somatosensory System ◽  
Tactile Perception ◽  
Sensory Innervation ◽  
Medial Nucleus ◽  
Functional Maturation ◽  
Body Regions ◽  
The Face ◽  
Posterior Medial Nucleus ◽  
Active Exploration

1. The hypothesis that active exploration of objects is required for the functional maturation of neuronal circuits subserving tactile perception was tested by subjecting 8- to 11-day old rats to a complete unilateral section of the facial nerve. This procedure selectively abolished whisker protraction movements without affecting the sensory innervation of the facial vibrissae, the tactile organs used by rats to discriminate object texture and shape. 2. Six to 14 mo after the facial nerve section, simultaneous recordings of neuronal ensembles located in the ventral posterior medial nucleus (VPM) of the thalamus revealed a marked reduction in receptive field (RF) size (in terms of number of whiskers), and the formation of abnormal RF surrounds, spanning the face and contiguous body regions. In addition, the directional organization of VPM RFs, represented by caudal to rostral shifts in RF centers over 30 ms following whisker stimulation, was greatly reduced in these animals. 3. These results suggest that neonatal active tactile exploration is required to establish normal spatiotemporal patterning of neuronal RFs within the somatosensory system, and consequently, to develop normal tactile perception.

scholarly journals Stimulus Parameters Influence Characteristics of Optical Intrinsic Signal Responses in Somatosensory Cortex

1995 ◽  
Vol 15 (6) ◽  
pp. 1109-1120 ◽  
Author(s):  
Anne J. Blood ◽  
Sanjiv M. Narayan ◽  
Arthur W. Toga
Keyword(s):  
Barrel Cortex ◽  
Stimulus Frequency ◽  
Onset Time ◽  
Absolute Number ◽  
Regions Of Interest ◽  
Response Magnitude ◽  
Intrinsic Signal ◽  
Time To Peak ◽  
Optical Intrinsic Signal ◽  
Signal Response

Optical imaging of intrinsic signals was performed in the barrel cortex of the rat during whisker deflections of varying frequencies (1 to 20 Hz) and durations (0.1 to 5 s). A dose–response relationship was shown between these stimuli and the characteristics of the optically recorded intrinsic signal response. At constant frequencies, longer stimulus durations increased response magnitude, as defined by mean pixel value in statistically determined regions of interest. At constant durations, higher stimulus frequencies increased response magnitude. Response magnitude was also increased by greater numbers of deflections. When stimulus number was constant, there were no differences in response magnitude, regardless of stimulus frequency and duration. Spatial extent of responses, as defined by number of pixels in regions of interest, did not differ between stimulus frequencies, durations, or numbers. Comparison of the time to reach peak intrinsic signal response after stimulus onset (“time-to-peak”) suggested that higher frequencies were associated with faster time-to-peak. Registration of intrinsic signal responses with cytochrome oxidase-stained whisker barrels demonstrated that responses were located over the barrel corresponding to the stimulated whisker. In summary, we have shown that the absolute number of stimuli delivered to the system is, at least for short stimulus periods (≤5 s), a determining factor for the magnitude of these responses, whereas stimulus frequency appears to influence time-to-peak response.

scholarly journals Decreased Heterogeneity of Capillary Plasma Flow in the Rat Whisker-Barrel Cortex during Functional Hyperemia

1996 ◽  
Vol 16 (6) ◽  
pp. 1300-1306 ◽  
Author(s):  
Johannes Vogel ◽  
Wolfgang Kuschinsky
Keyword(s):  
Evans Blue ◽  
Barrel Cortex ◽  
Stimulation Frequency ◽  
Blue Dye ◽  
Functional Hyperemia ◽  
Transit Times ◽  
Mystacial Vibrissae ◽  
The Right ◽  
The Brain ◽  
Experimental Group

The pattern of capillary plasma perfusion was investigated in the rat brain during functional activation. Functional hyperemia was induced in the left whisker-barrel cortex by deflection of the right mystacial vibrissae for 2 min at frequencies of 1–7 Hz. Rats were decapitated under anesthesia 3 s after i.v. bolus injection of Evans blue dye. The steep increase of the arterial dye concentration ensures that divergent capillary plasma transit times result in unequal intracapillary dye concentrations. Plasma perfusion heterogeneity was determined from the coefficient of variation (CV) of Evans blue concentrations measured in numerous single capillaries of the whisker-barrel cortex. Functional hyperemia was quantified from measurements of CBF using the [14C]-iodoantipyrine technique in a second experimental group. CBF in the left whisker-barrel cortex increased with the stimulation frequency and was maximal at 5 Hz compared to the right side. Conversely, plasma perfusion heterogeneity decreased with stimulation frequency in a reciprocal way, being minimal at 5 Hz. Results indicate a decrease in the microcirculatory flow heterogeneity during functional hyperemia in the brain.

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