scholarly journals THE REACTION OF SOMATOSENSORY CORTICAL NEURONS TO STIMULATION OF THE POSTERIOR THALAMUS IN WAG/RIJ RATS

2019 ◽  
Author(s):  
V.V. Raevsky ◽  
◽  
E.Yu. Sitnikova ◽  
D.A. Tsvetaeva ◽  
◽  
...  
Keyword(s):  
Cortical Neurons ◽  
Posterior Thalamus ◽  
Stimulation Of

Gustatory neural coding in the monkey cortex: stimulus quality

1991 ◽  
Vol 66 (4) ◽  
pp. 1156-1165 ◽  
Author(s):  
V. L. Smith-Swintosky ◽  
C. R. Plata-Salaman ◽  
T. R. Scott
Keyword(s):  
Cortical Neurons ◽  
Neural Coding ◽  
Monosodium Glutamate ◽  
Stimulus Array ◽  
Cortical Region ◽  
Stimulus Similarity ◽  
Somatosensory Stimulation ◽  
Wide Range ◽  
Response Profiles ◽  
Stimulation Of

1. Extracellular action potentials were recorded from 50 single neurons in the insular-opercular cortex of two alert cynomolgus monkeys during gustatory stimulation of the tongue and palate. 2. Sixteen stimuli, including salts, sugars, acids, alkaloids, monosodium glutamate, and aspartame, were chosen to represent a wide range of taste qualities. Concentrations were selected to elicit a moderate gustatory response, as determined by reference to previous electrophysiological data or to the human psychophysical literature. 3. The cortical region over which taste-evoked activity could be recorded included the frontal operculum and anterior insula, an area of approximately 75 mm3. Taste-responsive cells constituted 50 (2.7%) of the 1,863 neurons tested. Nongustatory cells responded to mouth movement (20.7%), somatosensory stimulation of the tongue (9.6%), stimulus approach or anticipation (1.7%), and tongue extension (0.6%). The sensitivities of 64.6% of these cortical neurons could not be identified by our stimulation techniques. 4. Taste cells had low spontaneous activity levels (3.7 +/- 3.0 spikes/s, mean +/- SD) and showed little inhibition. They were moderately broadly tuned, with a mean entropy coefficient of 0.76 +/- 0.17. Excitatory responses were typically not robust. 5. Hierarchical cluster analysis was used to determine whether neurons could be divided into discrete types, as defined by their response profiles to the entire stimulus array. There was an apparent division of response profiles into four general categories, with primary sensitivities to sodium (n = 18), glucose (n = 15), quinine (n = 12), and acid (n = 5). However, these categories were not statistically independent. Therefore the notion of functionally distinct neuron types was not supported by an analysis of the distribution of response profiles. It was the case, however, that neurons in the sodium category could be distinguished from other neurons by their relative specificity. 6. The similarity among the taste qualities represented by this stimulus array was assessed by calculating correlations between the activity profiles they elicited from these 50 neurons. The results generally confirmed expectations derived from human psychophysical studies. In a multidimensional representation of stimulus similarity, there were groups that contained acids, sodium salts, and chemicals that humans label bitter and sweet. 7. The small proportion of insular-opercular neurons that are taste sensitive and the low discharge rates that taste stimuli are able to evoke from them suggest a wider role for this cortical area than just gustatory coding.(ABSTRACT TRUNCATED AT 400 WORDS)

Excitatory amino acid receptor-mediated transmission in geniculocortical and intracortical pathways within visual cortex

1991 ◽  
Vol 66 (1) ◽  
pp. 293-306 ◽  
Author(s):  
L. J. Larson-Prior ◽  
P. S. Ulinski ◽  
N. T. Slater
Keyword(s):  
Visual Cortex ◽  
Amino Acid ◽  
Cortical Neurons ◽  
Excitatory Amino Acid ◽  
Nmda Antagonist ◽  
Receptor Subtypes ◽  
Excitatory Amino Acid Receptor ◽  
Visual Cortical ◽  
Stimulation Of

1. A preparation of turtle (Chrysemys picta and Pseudemys scripta) brain in which the integrity of the intracortical and geniculocortical pathways in visual cortex are maintained in vitro has been used to differentiate the excitatory amino acid (EAA) receptor subtypes involved in geniculocortical and intracortical synapses. 2. Stimulation of the geniculocortical fibers at subcortical loci produces monosynaptic excitatory postsynaptic potentials (EPSPs) in visual cortical neurons. These EPSPs are blocked by the broad-spectrum EAA receptor antagonist kynurenate (1-2 mM) and the non-N-methyl-D-aspartate (NMDA) antagonist 6, 7-dinitroquinoxaline-2,3-dione (DNQX, 10 microM), but not by the NMDA antagonist D,L-2-amino-5-phosphonovalerate (D,L-AP-5, 100 microM). These results indicate that the geniculocortical EPSP is mediated by EAAs that access principally, if not exclusively, EAA receptors of the non-NMDA subtypes. 3. Stimulation of intracortical fibers evokes compound EPSPs that could be resolved into three components differing in latency to peak. The component with the shortest latency was not affected by any of the EAA-receptor antagonists tested. The second component, of intermediate latency, was blocked by kyurenate and DNQX but not by D,L-AP-5. The component of longest latency was blocked by kynurenate and D,L-AP-5, but not by DNQX. These results indicate that the compound intracortical EPSP is comprised of three pharmacologically distinct components that are mediated by an unknown receptor, by quisqualate/kainate, and by NMDA receptors, respectively. 4. Repetitive stimulation of intracortical pathways at 0.33 Hz produces a dramatic potentiation of the late, D,L-AP-5-sensitive component of the intracortical EPSP. 5. These experiments lead to a hypothesis about the subtypes of EAA receptors that are accessed by the geniculocortical and intracortical pathways within visual cortex.

The nitric oxide synthase inhibitor, N-monomethyl-L-arginine blocks induction of a long-term potentiation-like phenomenon in rat medial frontal cortical neurons in vitro

1993 ◽  
Vol 70 (3) ◽  
pp. 1255-1259 ◽  
Author(s):  
A. V. Nowicky ◽  
L. J. Bindman
Keyword(s):  
Nitric Oxide ◽  
Cortical Neurons ◽  
Long Term Potentiation ◽  
Control Group ◽  
Term Potentiation ◽  
The Mean ◽  
Synthase Inhibitor ◽  
Stimulation Of

1. Nitric oxide has been implicated in the production of long-term depression (LTD) in the cerebellum and in the production of long-term potentiation (LTP) and LTD in the hippocampus. We now provide evidence of its involvement in the induction of long-term synaptic potentiation in in vitro slices in the cerebral cortex of the rat. 2. Intracellular recordings were made from layer V neurons in the medial frontal cortex, and excitatory synaptic potentials (EPSPs) were evoked by electrical stimulation of layers II/III. Tetanic stimulation of this pathway may induce LTD or LTP or no change at these synapses. First we established experimental conditions under which a long lasting potentiation could be induced with a high incidence (> 60%), namely perfusion of slices with 1 microM bicuculline methiodide, second the use of increased shock duration in the tetanic conditioning stimuli, third and most important the addition of QX-314 to the microelectrode to reduce potassium conductances. Because the potentiation of the mean EPSP slope was significantly greater than the control at 40-min postconditioning, but was declining throughout this period, we refer to it for brevity as LTP, but strictly class it as an LTP-like phenomenon. 3. The nitric oxide (NO) synthase inhibitor interfered with the production of LTP. In the control group of neurons (n = 13) the mean depolarizing slope of the EPSP at 30-min post-conditioning was 142.7 +/- 2% (mean +/- SE) of the prestimulation control.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Synaptic Conductances and Integrative Properties During Electrically Induced EEG-Activated States in Neocortical Neurons In Vivo

2005 ◽  
Vol 94 (4) ◽  
pp. 2805-2821 ◽  
Author(s):  
Michael Rudolph ◽  
Joe Guillaume Pelletier ◽  
Denis Paré ◽  
Alain Destexhe
Keyword(s):  
Cortical Neurons ◽  
Computational Models ◽  
Input Resistance ◽  
Synaptic Activity ◽  
Intracellular Recordings ◽  
Neocortical Neurons ◽  
Up States ◽  
Conductance State ◽  
Stimulation Of

The activation of the electroencephalogram (EEG) is paralleled with an increase in the firing rate of cortical neurons, but little is known concerning the conductance state of their membrane and its impact on their integrative properties. Here, we combined in vivo intracellular recordings with computational models to investigate EEG-activated states induced by stimulation of the brain stem ascending arousal system. Electrical stimulation of the pedonculopontine tegmental (PPT) nucleus produced long-lasting (≈20 s) periods of desynchronized EEG activity similar to the EEG of awake animals. Intracellularly, PPT stimulation locked the membrane into a depolarized state, similar to the up-states seen during deep anesthesia. During these EEG-activated states, however, the input resistance was higher than that during up-states. Conductance measurements were performed using different methods, which all indicate that EEG-activated states were associated with a synaptic activity dominated by inhibitory conductances. These results were confirmed by computational models of reconstructed pyramidal neurons constrained by the corresponding intracellular recordings. These models indicate that, during EEG-activated states, neocortical neurons are in a high-conductance state consistent with a stochastic integrative mode. The amplitude and timing of somatic excitatory postsynaptic potentials were nearly independent of the position of the synapses in dendrites, suggesting that EEG-activated states are compatible with coding paradigms involving the precise timing of synaptic events.

Intrinsic discharge patterns and somatosensory inputs for neurons in raccoon primary somatosensory cortex

1994 ◽  
Vol 72 (6) ◽  
pp. 2827-2839 ◽  
Author(s):  
P. J. Istvan ◽  
P. Zarzecki
Keyword(s):  
Somatosensory Cortex ◽  
Cortical Neurons ◽  
Primary Somatosensory Cortex ◽  
Membrane Properties ◽  
Postsynaptic Potentials ◽  
Synaptic Inputs ◽  
Ionic Conductances ◽  
Discharge Patterns ◽  
Intrinsic Membrane Properties ◽  
Stimulation Of

1. Discharge patterns of neurons are regulated by synaptic inputs and by intrinsic membrane properties such as their complement of ionic conductances. Discharge patterns evoked by synaptic inputs are often used to identify the source and modality of sensory input. However, the interpretation of these discharge patterns may be complicated if different neurons respond to the same synaptic input with a variety of discharge patterns due to differences in intrinsic membrane properties. The purposes of this study were 1) to investigate intrinsic discharge patterns of neurons in primary somatosensory cortex of raccoon in vivo and 2) to use somatosensory postsynaptic potentials evoked by stimulation of forepaw digits to determine thalamocortical connectivity for the same neurons. 2. Conventional intracellular recordings with sharp electrodes were made from 121 neurons in the cortical representation of glabrous skin of digit four (d4). Intracellular injection of identical current pulses (100-120 ms in duration) elicited various patterns of discharge in different neurons. Neurons were classified on the basis of these intrinsic patterns of discharge, rates of spike adaptation, and characteristics of spike waveforms. Three main groups were identified: regular spiking (RS) neurons, intrinsic bursting (IB) neurons, and fast spiking (FS) neurons. Subclasses were identified for the RS and IB groups. 3. Neurons were tested for somatosensory inputs by stimulating electrically d3, d4, and d5. Excitatory postsynaptic potentials (EPSPs) were elicited in 100% of the neurons by electrical stimulation of d4, the "on-focus" digit. EPSPs were usually followed by inhibitory postsynaptic potentials (IPSPs). Many neurons (41%) responded with EPSP-IPSP sequences after stimulation of d3 or d5, the "off-focus" digits. 4. Latencies of somatosensory EPSPs and IPSPs were used to determine the synaptic order in the cortical circuitry of RS, IB, and FS neurons. EPSPs with monosynaptic thalamocortical latencies were recorded in RS, IB, and FS neurons. 5. We conclude that precise patterns of neural discharge in primary somatosensory cortex cannot be reliable estimates of sensory inputs reaching these neurons because patterns of discharge are so strongly influenced by intrinsic membrane properties. Ionic conductances governing patterns of neuronal discharge seem almost identical in intact cortex of raccoon, rat, and cat, and in slices of rodent cortex, because similar patterns of discharge are found. The consistency of patterns of discharge across species and types of preparation suggests that these intrinsic membrane properties are a general property of cerebral cortical neurons and should be considered when evaluation sensory coding by these neurons.

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