Associative Interactions Within the Superficial Layers of the Entorhinal Cortex of the Guinea Pig

2002 ◽  
Vol 88 (3) ◽  
pp. 1159-1165 ◽  
Author(s):  
Gerardo Biella ◽  
Laura Uva ◽  
Ulrich G. Hofmann ◽  
Marco De Curtis
Keyword(s):  
Guinea Pig ◽  
Entorhinal Cortex ◽  
Current Source ◽  
Field Potential ◽  
Superficial Layer ◽  
Delayed Response ◽  
Lateral Olfactory Tract ◽  
Deep Layers ◽  
Stimulation Of

Associative fiber systems in the entorhinal cortex (EC) have been extensively studied in different mammals with tracing techniques. The largest contingent of intra-EC cortico-cortical fibers runs in the superficial layers and is distributed predominantly within longitudinal cortical bands. We studied the patterns of intrinsic EC connectivity in the in vitro isolated guinea pig brain preparation by performing current-source density analysis of field potential laminar profiles recorded with multi-channel silicon probes. The response pattern evoked by stimulation of the lateral olfactory tract was utilized to identify the lateral (l-EC) and medial (m-EC) entorhinal cortex. Stimulation of the deep layers did not evoke consistent responses. Local stimulation of the superficial layers in different portions of the EC induced an early, possibly direct response restricted to layer II–III in the close proximity to the stimulating electrode, followed by a late potential in the superficial layer I, that propagated at distance with a progressively increasing latency. The monosynaptic nature of the delayed response was verified by applying a pairing test. The results demonstrated that stimulation in the rostral-medial part of the EC generated activity restricted to the rostral pole of the l-EC, stimulation of the m-EC induced an associative activation that propagated rostrocaudally within the m-EC, stimulation of the caudal pole of the m-EC induced an additional response directed laterally, and stimulation of the lateral band of the EC determined a prominent longitudinal propagation of neuronal activity, but also induced associative potentials that propagated medially. The results are in partial agreement with the general picture derived from the anatomical studies performed in different species. Even though the largest associative interactions between superficial layers are restricted within either the m-EC or the l-EC, both rostral and caudal stimuli in the EC region close to the rhinal sulcus induced activity that propagated across the border between l- and m-EC.

Stimulation of the Parasubiculum Modulates Entorhinal Cortex Responses to Piriform Cortex Inputs In Vivo

2004 ◽  
Vol 92 (2) ◽  
pp. 1226-1235 ◽  
Author(s):  
Douglas A. Caruana ◽  
C. Andrew Chapman
Keyword(s):  
Entorhinal Cortex ◽  
Hippocampal Formation ◽  
Piriform Cortex ◽  
Current Source ◽  
Field Potential ◽  
Implanted Electrodes ◽  
Deep Layers ◽  
Negative Field ◽  
Stimulation Of

Although a major output of the hippocampal formation is from the subiculum to the deep layers of the entorhinal cortex, the parasubiculum projects to the superficial layers of the entorhinal cortex and may therefore modulate how the entorhinal cortex responds to sensory inputs from other cortical regions. Recordings at multiple depths in the entorhinal cortex were first used to characterize field potentials evoked by stimulation of the parasubiculum in urethan-anesthetized rats. Current source density analysis showed that a prominent surface-negative field potential component is generated by synaptic activation in layer II. The surface-negative field potential was also observed in rats with chronically implanted electrodes. The response was maintained during short stimulation trains of ≤125 Hz, suggesting that it is generated by activation of monosynaptic inputs to the entorhinal cortex. The piriform cortex also projects to layer II of the entorhinal cortex, and interactions between parasubicular and piriform cortex inputs were investigated using double-site stimulation tests. Simultaneous activation of parasubicular and piriform cortex inputs with high-intensity pulses resulted in smaller synaptic potentials than were expected on the basis of summing the individual responses, consistent with the termination of both pathways onto a common population of neurons. Paired-pulse tests were then used to assess the effect of parasubicular stimulation on responses to piriform cortex stimulation. Responses of the entorhinal cortex to piriform cortex inputs were inhibited when the parasubiculum was stimulated 5 ms earlier and were enhanced when the parasubiculum was stimulated 20–150 ms earlier. These results indicate that excitatory inputs to the entorhinal cortex from the parasubiculum may enhance the propagation of neuronal activation patterns into the hippocampal circuit by increasing the responsiveness of the entorhinal cortex to appropriately timed inputs.

Converging Inputs to the Entorhinal Cortex From the Piriform Cortex and Medial Septum: Facilitation and Current Source Density Analysis

1997 ◽  
Vol 78 (5) ◽  
pp. 2602-2615 ◽  
Author(s):  
C. Andrew Chapman ◽  
Ronald J. Racine
Keyword(s):  
Entorhinal Cortex ◽  
Piriform Cortex ◽  
Current Source ◽  
Field Potential ◽  
Medial Septum ◽  
Current Source Density ◽  
Short Term ◽  
Source Density ◽  
Potential Component ◽  
Stimulation Of

Chapman, C. Andrew and Ronald J. Racine. Converging inputs to the entorhinal cortex from the piriform cortex and medial septum: facilitation and current source density analysis. J. Neurophysiol. 78: 2602–2615, 1997. The entorhinal cortex receives sensory inputs from the piriform cortex and modulatory inputs from the medial septum. To examine short-term synaptic facilitation effects in these pathways, current source density (CSD) analysis was used first to localize the entorhinal cortex membrane currents, which generate field potentials evoked by stimulation of these afferents. Field potentials were recorded at 50-μm intervals through the medial entorhinal cortex in urethan-anesthetized rats and the one-dimensional CSD was calculated. Piriform cortex stimulation evoked a surface-negative, deep-positive field potential component in the entorhinal cortex with mean onset and peak latencies of 10.4 and 18.4 ms. The component followed brief 100-Hz stimulation, consistent with a monosynaptic response. CSD analysis linked the component to a current sink, which often began in layer I before peaking in layer II. A later, surface-positive field potential component peaked at latencies near 45 ms and was associated with a current source in layer II. Medial septal stimulation evoked positive and negative field potential components which peaked at latencies near 7 and 16 ms, respectively. A weaker and more prolonged surface-negative, deep-positive component peaked at latencies near 25 ms. The early components were generated by currents in the hippocampal formation, and the late surface-negative component was generated by currents in layers II to IV of the entorhinal cortex. Short-term facilitation effects in conscious animals were examined using electrodes chronically implanted near layer II of the entorhinal cortex. Paired-pulse stimulation of the piriform cortex at interpulse intervals of 30 and 40 ms caused the largest facilitation (248%) of responses evoked by the second pulse. Responses evoked by medial septal stimulation also were facilitated maximally (59%) by a piriform cortex conditioning pulse delivered 30–40 ms earlier. Paired pulse stimulation of the medial septum caused the largest facilitation (149%) at intervals of 70 ms, but piriform cortex evoked responses were facilitated maximally (46%) by a septal conditioning pulse 100–200 ms earlier. Frequency potentiation effects were maximal during 12- to 18-Hz stimulation of either the piriform cortex or medial septum. Occlusion tests suggested that piriform cortex and medial septal efferents activate the same neurons. The CSD analysis results show that evoked field potential methods can be used effectively in chronically prepared animals to examine synaptic responses in the converging inputs from the piriform cortex and medial septum to the entorhinal cortex. The short-term potentiation phenomena observed here suggest that low-frequency activity in these pathways during endogenous oscillatory states may enhance entorhinal cortex responsivity to olfactory inputs.

scholarly journals Distribution of the Olfactory Fiber Input Into the Olfactory Tubercle of the In Vitro Isolated Guinea Pig Brain

2009 ◽  
Vol 101 (3) ◽  
pp. 1613-1619 ◽  
Author(s):  
Giovanni Carriero ◽  
Laura Uva ◽  
Vadym Gnatkovsky ◽  
Marco de Curtis
Keyword(s):  
Guinea Pig ◽  
Piriform Cortex ◽  
Field Potential ◽  
Lateral Part ◽  
Olfactory Tubercle ◽  
Olfactory Tract ◽  
Pig Brain ◽  
Guinea Pig Brain ◽  
Stimulation Of

The olfactory tubercle (OT) is a cortical component of the olfactory system involved in reward mechanisms of drug abuse. This region covers an extensive part of the rostral ventral cerebrum and is relatively poorly studied. The intrinsic network interactions evoked by olfactory input are analyzed in the OT of the in vitro isolated guinea pig brain by means of field potential analysis and optical imaging of voltage-sensitive signals. Stimulation of the lateral olfactory tract induces a monosynaptic response that progressively decreases in amplitude from lateral to medial. The monosynaptic input induces a disynaptic response that is proportionally larger in the medial portion of the OT. Direct stimulation of the piriform cortex and subsequent lesion of this pathway showed the existence of an associative disynaptic projection from the anterior part of the piriform cortex to the lateral part of the OT that integrates with the component mediated by the local intra-OT collaterals. Optical and electrophysiological recordings of the signals evoked by stimulation of the olfactory tract during arterial perfusion with the voltage-sensitive dye di-2-ANEPEQ confirmed the pattern of distribution of the mono and disynaptic responses in the OT. Finally, current source density analysis of laminar profiles recorded with 16-channel silicon probes confirmed that the monosynaptic and disynaptic potentials localize in the most superficial and the deep portions of the plexiform layer I, as suggested by previous reports. This study sets the standard for further analysis of the modulation of network properties in this largely unexplored brain region.

Pharmacologic sensitivity of amino acid responses and synaptic activation of in vitro prepyriform neurons

1982 ◽  
Vol 48 (6) ◽  
pp. 1289-1301 ◽  
Author(s):  
N. Hori ◽  
C. R. Auker ◽  
D. J. Braitman ◽  
D. O. Carpenter
Keyword(s):  
Amino Acid ◽  
Pyramidal Neurons ◽  
Excitatory Amino Acid ◽  
Field Potential ◽  
Diaminopimelic Acid ◽  
Diethyl Ester ◽  
Lateral Olfactory Tract ◽  
Homocysteic Acid ◽  
Stimulation Of

1. In an effort to identify the neurotransmitter released from terminals of the lateral olfactory tract (LOT) we have studied excitatory amino acid agonist and antagonist actions on population and single-unit responses in submerged and perfused slices of rat prepyriform cortex. Previous studies suggest that the transmitter at this synapse is either aspartate (Asp) or glutamate (Glu). 2. The field potential reflecting the monosynaptic activation of pyramidal neurons after stimulation of the LOT was reversibly depressed by bath perfusion of agonists, with an order of potency being kainic acid (KA) greater than N-methyl-DL-aspartate (NMDA) greater than homocysteic acid (HC) greater than Asp = Glu. 3. The synaptic field potential was essentially unaffected by DL-alpha-aminoadipic acid (AA), 2-amino-3-phosphonopropionic acid (APP), and DL-alpha-diaminopimelic acid (DAPA), all presumed to be selective for Asp receptors, and by L-glutamic acid diethyl ester (GDEE), presumed to be specific for Glu receptors. The field potential was depressed or abolished by 2-amino-4-phosphonobutyric acid (APB), an agent known to block Glu responses in insect muscle. 4. The effects of ionophoretic application of agonists were studied on single neurons recorded extracellularly. While there was some variability among neurons in relative agonist potency, all neurons were excited by the five agonists with relative potencies in general similar to those observed for the field potentials. 5. Responses to Glu and Asp were unaffected by AA, GDEE, and APB at concentrations up to 5 X 10(-3) M. Responses to KA, NMDA, and HC were often depressed by APB but were unaffected by the other antagonists. The excitation on stimulation of the LOT was consistently, rapidly, and reversibly blocked by APB. 6. These observations are not consistent with either Glu or Asp being the neurotransmitter of the LOT.

High-frequency oscillations and seizure-like discharges in the entorhinal cortex of the in vitro isolated guinea pig brain

2017 ◽  
Vol 130 ◽  
pp. 21-26 ◽  
Author(s):  
Laura Uva ◽  
Davide Boido ◽  
Massimo Avoli ◽  
Marco de Curtis ◽  
Maxime Lévesque
Keyword(s):  
Guinea Pig ◽  
Entorhinal Cortex ◽  
High Frequency ◽  
High Frequency Oscillations ◽  
Pig Brain ◽  
Guinea Pig Brain

Protective role of epithelium in the guinea pig airway

1989 ◽  
Vol 66 (4) ◽  
pp. 1547-1552 ◽  
Author(s):  
M. Munakata ◽  
I. Huang ◽  
W. Mitzner ◽  
H. Menkes
Keyword(s):  
Guinea Pig ◽  
Protective Role ◽  
Airway Epithelial ◽  
Serosal Side ◽  
Epithelial Surface ◽  
Airway Responses ◽  
Airway Tone ◽  
Stimulation Of

We developed an in vitro system to assess the role of the epithelium in regulating airway tone using the intact guinea pig trachea (J. Appl. Physiol. 64: 466–471, 1988). This method allows us to study the response of the airway when its inner epithelial surface or its outer serosal surface is stimulated independently. Using this system we evaluated how the presence of intact epithelium can affect pharmacological responsiveness. We first examined responses of tracheae with intact epithelium to histamine, acetylcholine, and hypertonic KCl when stimulated from the epithelial or serosal side. We then examined the effect of epithelial denudation on the responses to these agonists. With an intact epithelium, stimulation of the inner epithelial side always caused significantly smaller changes in diameter than stimulation of the outer serosal side. After mechanical denudation of the epithelium, these differences were almost completely abolished. In the absence of intact epithelium, the trachea was 35-fold more sensitive to histamine and 115-fold more sensitive to acetylcholine when these agents were applied to the inner epithelial side. In addition, the presence of an intact epithelium almost completely inhibited any response to epithelial side challenge with hypertonic KCl. These results indicate that the airway epithelial layer has a potent protective role in airway responses to luminal side stimuli, leading us to speculate that changes in airway reactivity measured in various conditions including asthma may result in part from changes in epithelial function.

Some species differences in the intrinsic factor stimulation of B12 uptake by small intestine in vitro

1959 ◽  
Vol 197 (4) ◽  
pp. 926-928 ◽  
Author(s):  
T. Hastings Wilson ◽  
Elliott W. Strauss
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Species Differences ◽  
Intrinsic Factor ◽  
Vitamin B ◽  
Guinea Pig Ileum ◽  
Rat Intestine ◽  
Intrinsic Factors ◽  
Stimulation Of

Sacs of everted small intestine from a variety of animals were incubated in bicarbonate-saline containing vitamin B12 with and without intrinsic factor (IF). B12 uptake by rat intestine was stimulated only by its own intrinsic factor. Guinea pig ileum responded to all intrinsic factors tested (guinea pig, rat, hog, hamster, human being and rabbit). The intestines of hamster and rabbit were intermediate in specificity, responding to some, but not all, of the IF preparations. Species differences occur in both the intestine and intrinsic factor preparations. The guinea pig ileum was suggested as a possible assay for both hog and human IF.

Electrophysiological properties of neurons in guinea pig bronchial parasympathetic ganglia

1990 ◽  
Vol 259 (6) ◽  
pp. L403-L409 ◽  
Author(s):  
A. C. Myers ◽  
B. J. Undem ◽  
D. Weinreich
Keyword(s):  
Guinea Pig ◽  
Vagus Nerve ◽  
Action Potentials ◽  
Receptor Activation ◽  
Membrane Properties ◽  
Constant Current ◽  
Parasympathetic Ganglia ◽  
Stimulation Of ◽  
Passive Membrane

Active and passive membrane membrane properties of parasympathetic neurons were examined in vitro in a newly localized ganglion on the right bronchus of the guinea pig. Neurons could be classified as “tonic” or “phasic” based on their action potential discharge response to suprathreshold depolarizing constant current steps. Tonic neurons (39%) responded with repetitive action potentials sustained throughout the current step, whereas phasic neurons (61%) responded with an initial burst of action potentials at the onset of the step but then accommodated. Tonic and phasic neurons could not be differentiated by other active or passive membrane properties. Electrical stimulation of the vagus nerve elicited one to three temporally distinct fast nicotinic excitatory potentials, and tetanic stimulation of the vagus nerve evoked slow depolarizing (10% of neurons) and hyperpolarizing (25% of neurons) potentials; the latter was mimicked by muscarinic receptor activation. Similar slow and fast postsynaptic potentials were observed in both tonic and phasic neurons. We suggest neurons within the bronchial ganglion possess membrane and synaptic properties capable of integrating presynaptic stimuli.

Carbachol Induces Fast Oscillations in the Medial but not in the Lateral Entorhinal Cortex of the Isolated Guinea Pig Brain

1999 ◽  
Vol 82 (5) ◽  
pp. 2441-2450 ◽  
Author(s):  
Solange van der Linden ◽  
Ferruccio Panzica ◽  
Marco de Curtis
Keyword(s):  
Guinea Pig ◽  
Entorhinal Cortex ◽  
Gamma Oscillations ◽  
Gamma Activity ◽  
Oscillatory Activity ◽  
Medial Entorhinal Cortex ◽  
Arterial Perfusion ◽  
Fast Oscillations ◽  
Guinea Pig Brain

Fast oscillations at 25–80 Hz (gamma activity) have been proposed to play a role in attention-related mechanisms and synaptic plasticity in cortical structures. Recently, it has been demonstrated that the preservation of the entorhinal cortex is necessary to maintain gamma oscillations in the hippocampus. Because gamma activity can be reproduced in vitro by cholinergic activation, this study examined the characteristics of gamma oscillations induced by arterial perfusion or local intracortical injections of carbachol in the entorhinal cortex of the in vitro isolated guinea pig brain preparation. Shortly after carbachol administration, fast oscillatory activity at 25.2–28.2 Hz was observed in the medial but not in the lateral entorhinal cortex. Such activity was transiently associated with oscillations in the theta range that showed a variable pattern of distribution in the entorhinal cortex. No oscillatory activity was observed when carbachol was injected in the lateral entorhinal cortex. Gamma activity in the medial entorhinal cortex showed a phase reversal at 200–400 μm, had maximal amplitude at 400–500 μm depth, and was abolished by arterial perfusion of atropine (5 μM). Local carbachol application in the medial entorhinal cortex induced gamma oscillations in the hippocampus, whereas no oscillations were observed in the amygdala and in the piriform, periamygdaloid, and perirhinal cortices ipsilateral and contralateral to the carbachol injection. Hippocampal oscillations had higher frequency than the gamma activity recorded in the entorhinal cortex, suggesting the presence of independent generators in the two structures. The selective ability of the medial but not the lateral entorhinal cortex to generate gamma activity in response to cholinergic activation suggests a differential mode of signal processing in entorhinal cortex subregions.

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