bluuebunny/crossref_metadata_2025 huggingface dataset:
Object and Place Memory in the Macaque Entorhinal Cortex
Authors: Suzuki Wendy A. , Miller Earl K. , Desimone Robert
Published: December 2017

Suzuki, Wendy A., Earl K. Miller, and Robert Desimone. Object and place memory in the macaque entorhinal cortex. J. Neurophysiol. 78: 1062–1081, 1997. Lesions of the entorhinal cortex in humans, monkeys, and rats impair memory for a variety of kinds of information, including memory for objects and places. To begin to understand the contribution of entorhinal cells to different forms of memory, responses of entorhinal cells were recorded as monkeys performed either an object or place memory task. The object memory task was a variation of delayed matching to sample. A sample picture was presented at the start of the trial, followed by a variable sequence of zero to four test pictures, ending with a repetition of the sample (i.e., a match). The place memory task was a variation of delayed matching to place. In this task, a cue stimulus was presented at a variable sequence of one to four “places” on a computer screen, ending with a repetition of one of the previously shown places (i.e., a match). For both tasks, the animals were rewarded for releasing a bar to the match. To solve these tasks, the monkey must 1) discriminate the stimuli, 2) maintain a memory of the appropriate stimuli during the course of the trial, and 3) evaluate whether a test stimulus matches previously presented stimuli. The responses of entorhinal cortex neurons were consistent with a role in all three of these processes in both tasks. We found that 47% and 55% of the visually responsive entorhinal cells responded selectively to the different objects or places presented during the object or place task, respectively. Similar to previous findings in prefrontal but not perirhinal cortex on the object task, some entorhinal cells had sample-specific delay activity that was maintained throughout all of the delay intervals in the sequence. For the place task, some cells had location-specific maintained activity in the delay immediately following a specific cue location. In addition, 59% and 22% of the visually responsive cells recorded during the object and place task, respectively, responded differently to the test stimuli according to whether they were matching or nonmatching to the stimuli held in memory. Responses of some cells were enhanced to matching stimuli, whereas others were suppressed. This suppression or enhancement typically occurred well before the animals' behavioral response, suggesting that this information could be used to perform the task. These results indicate that entorhinal cells receive sensory information about both objects and spatial locations and that their activity carries information about objects and locations held in short-term memory.
Experimental Down-Regulation of the NMDA Channel Associated With Synapse Pruning
Authors: Hickmott Peter W. , Constantine-Paton Martha
Published: December 2017

Hickmott, Peter W. and Martha Constantine-Paton. Experimental down-regulation of the NMDA channel associated with synapse pruning. J. Neurophysiol. 78: 1096–1107, 1997. The N-methyl-d-aspartate (NMDA) receptor has been implicated in activity-dependent synapse stabilization, but its role as a detector of correlated activity during development is debated. In the amphibian retinotectal system, synaptic sorting and stabilization occur throughout larval life, and map refinement is dependent on continuous NMDA receptor function. Moreover, tadpole tecta chronically treated with NMDA selectively fail to maintain retinal synapses wherever their activity correlations are lowest. To determine whether this synapse elimination is associated with a specific down-regulation of NMDA receptor function, whole cell voltage-clamp recordings were made from single neurons in tectal slices. After chronic NMDA treatment, decreases in the magnitude of NMDA currents were detected in glutamatergic synaptic currents, in agonist-evoked currents, and in single-channel currents activated by NMDA. The results suggest that the efficacy of NMDA receptors on tectal neurons determines the amount of correlation required to stabilize sets of tectal inputs during formation of the retinotectal projection.
Model With Distributed Vectorial Premotor Bursters Accounts for the Component Stretching of Oblique Saccades
Authors: Quaia Christian , Optican Lance M.
Published: December 2017

Quaia, Christian and Lance M. Optican. Model with distributed vectorial premotor bursters accounts for the component stretching of oblique saccades. J. Neurophysiol. 78: 1120–1134, 1997. During oblique saccades, the durations of the horizontal and vertical components are stretched until they are approximately equal. Models of the saccadic system have been proposed that provide a mechanism for that stretching. However, they fail to simulate the pattern of activity recorded from premotor medium lead burst neurons (MLBNs) in the brain stem. A new model of the saccadic system is proposed that accounts for both the component stretching of oblique movements and the pattern of activity recorded in MLBNs. MLBNs that project to horizontal (or vertical) motoneurons actually have a wide span of on-directions (the direction associated with the largest discharge) around the cardinal direction. We infer from the wide span of their on-directions that, at the level of individual MLBNs, the vectorial signal present in spatially organized structures (e.g., the superior colliculus) is not decomposed into the separate horizontal and vertical components represented by the motoneurons. Nonetheless, all prior models of the saccadic system have decomposed the vectorial premotor command into horizontal and vertical commands at the level of the MLBNs. That decomposition was explicit, because individual MLBNs, with a sine- or cosine-shaped directional tuning curve, were used. We propose here that the decomposition into horizontal and vertical commands is carried out only at the level of the motoneurons. This decomposition is implicit, because no single MLBN encodes the horizontal or vertical command; the command only exists implicitly in the activity of the population of MLBNs. The new vectorial burster model correctly simulates the pattern of activity recorded in primate MLBNs, and the components of its oblique saccades are stretched. Two mechanisms contribute to this stretching: the distribution of MLBN tuning curves and the inhibition exerted by the contralateral population of MLBNs. In contrast, feedback control of the saccade contributes negligibly to the stretching. Even though the vectorial burster model predicts a component stretching, it is not constrained to produce perfectly straight oblique saccades because no trajectory control is implemented. The amount of curvature depends on the similarity of the horizontal and vertical systems (both neural and mechanical). In this model, stretching is interpreted simply as a side effect of the properties of the MLBNs' tuning curves. The distributed MLBNs of the vectorial burster model forces the general organization of the saccadic system to be reconsidered. We propose that a distributed architecture in which several different neural systems cooperate is needed.
Central Versus Peripheral Determinants of Patterned Spike Activity in Rat Vibrissa Cortex During Whisking
Authors: Fee Michale S. , Mitra Partha P. , Kleinfeld David
Published: December 2017

Fee, Michale S., Partha P. Mitra, and David Kleinfeld. Central versus peripheral determinants of patterned spike activity in rat vibrissa cortex during whisking. J. Neurophysiol. 78: 1144–1149, 1997. We report on the relationship between single-unit activity in primary somatosensory vibrissa cortex of rat and the rhythmic movement of vibrissae. Animals were trained to whisk freely in air in search of food. Electromyographic (EMG) recordings from the mystatial pads served as a reference for the position of the vibrissae. A fast, oscillatory component in single-unit spike trains is correlated with vibrissa position within the whisk cycle. The phase of the correlation for different units is broadly distributed. A second, slowly varying component of spike activity correlates with the amplitude of the whisk cycle. For some units, the phase and amplitude correlations were of sufficient strength to allow the position of the whiskers to be accurately predicted from a single spike train. To determine whether the observed patterned spike activity was driven by motion of the vibrissae, as opposed to central pathways, we reversibly blocked the contralateral facial motor nerve during the behavioral task so that the rat whisked only on the ipsilateral side. The ipsilateral EMG served as a reliable reference signal. The fast, oscillatory component of the spike-EMG correlation disappears when the facial motor nerve is blocked. This implies that the position of vibrissae within a cycle is encoded through direct sensory activation. The slowly varying component of the spike-EMG correlation is unaffected by the block. This implies that the amplitude of whisking is likely to be mediated by corollary discharge. Our results suggest that motor cortex does not relay a reference signal to sensory cortex for positional information of the vibrissae during whisking.
Calcineurin Modulates G Protein-Mediated Inhibition of N-Type Calcium Channels in Rat Sympathetic Neurons
Authors: Zhu Yu , Yakel Jerrel L.
Published: December 2017

Zhu, Yu and Jerrel L. Yakel. Calcineurin modulates G protein-mediated inhibition of N-type calcium channels in rat sympathetic neurons. J. Neurophysiol. 78: 1161–1169, 1997. The modulation of N-type voltage-gated calcium (Ca2+) channels by G protein-coupled receptors was investigated in sympathetic neurons of the male rat major pelvic ganglion (MPG) with the use of whole cell patch-clamp recording techniques from acutely dissociated neurons. By inhibiting calcineurin, a Ca2+/calmodulin-regulatedprotein phosphatase, the α2noradrenergic and somatostatin receptor-induced inhibition of these N-type Ca2+channels was greatly reduced. Both of these receptor pathways utilize a pertussis toxin-sensitive G protein (GPTX). The guanosine 5′-o-(3-thiotriphosphate) (GTPγS)-induced decrease in the amplitude and activation kinetics of Ca2+currents, an effect that was similar to the activation of GPTX-coupled receptors, also was reduced by the inhibition of calcineurin. Calcineurin does not regulate the muscarinic receptor-induced inhibition of the N-type Ca2+channels, a pathway that utilizes a different G protein in the MPG neurons. Thus calcineurin appears to selectively regulate the coupling between the GPTXand the Ca2+channel.
Potentiation of NMDA Currents by Pituitary Adenylate Cyclase Activating Polypeptide in Neonatal Rat Sympathetic Preganglionic Neurons
Authors: Wu S. Y. , Dun N. J.
Published: December 2017

Wu, S. Y. and N. J. Dun. Potentiation of NMDA currents by pituitary adenylate cyclase activating polypeptide in neonatal rat sympathetic preganglionic neurons. J. Neurophysiol. 78: 1175–1179, 1997. Whole cell patch-clamp recordings were made from sympathetic preganglionic neurons (SPNs) in the intermediolateral cell column of thoracolumbar spinal cord slices of 12- to 16-day-old rats, and the effects of pituitary adenylate cyclase activating polypeptide (PACAP)-38 on N-methyl-d-aspartate (NMDA)- and kainate (KA)-induced inward currents were examined. PACAP, in concentrations (10–30 nM) that caused no significant change of holding currents, reversibly increased NMDA-induced currents but not KA-induced currents. At higher concentrations (>30 nM), the peptide produced a sustained inward current. The potentiating effect of PACAP was nullified by prior incubation of the slices with the adenylate cyclase inhibitor MDL-12,330A (25 μM). Further, superfusing the slices with the membrane-permeable cyclic AMP analogue N6,2′-0-dibutyryladenosine 3′:5′-cyclic monophosphate (100–300 μM) in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (700 μM) increased the NMDA currents. This result suggests that PACAP selectively increases NMDA-receptor-mediated responses in the rat SPNs, probably via a cyclic-AMP-dependent mechanism, providing evidence that the peptide may be involved in synaptic plasticity.
Antidromic Modulation of a Proprioceptor Sensory Discharge in Crayfish
Authors: Bévengut Michelle , Clarac François , Cattaert Daniel
Published: December 2017

Bévengut, Michelle, François Clarac, and Daniel Cattaert. Antidromic modulation of a proprioceptor sensory discharge in crayfish. J. Neurophysiol. 78: 1180–1183, 1997. In the proprioceptive neurons of the coxo-basal chortotonal organ, orthodromic spikes convey the sensory information from the cell somata (located peripherally) to the central output terminals. During fictive locomotion, presynaptic depolarizations of these central terminals elicit bursts of antidromic spikes that travel back to the periphery. To determine whether the antidromic spikes modified the orthodromic activity of the sensory neurons, single identified primary afferents of the proprioceptor were recorded intracellularly and stimulated in in vitro preparations of crayfish nervous system. Depolarizing current pulses were delivered in trains whose frequency and duration were controlled to reproduce bursts of antidromic spikes similar to those elicited during fictive locomotion. According to their frequencies, these antidromic bursts reduce or suppress the orthodromic discharges in both position- and movement-sensitive neurons. They induce both a long-lasting silence and a gradual recovery after their occurrences. Neither the collision between the afferent and the efferent messages nor the release of serotonin by the sensory neurons can explain these results. We therefore conclude that antidromic bursts produce a peripheral modulation of the orthodromic activity of the sensory neurons, modifying their sensitivity by mechanisms yet unknown.
Enhanced Synaptic Transmission in CA1 Hippocampus After Eyeblink Conditioning
Authors: Power John M. , Thompson Lucien T. , Moyer James R. , Disterhoft John F.
Published: December 2017

Power, John M., Lucien T. Thompson, James R. Moyer, Jr., and John F. Disterhoft. Enhanced synaptic transmission in CA1 hippocampus after eyeblink conditioning. J. Neurophysiol. 78: 1184–1187, 1997. CA1 field potentials evoked by Schaffer collateral stimulation of hippocampal slices from trace-conditioned rabbits were compared with those from naive and pseudoconditioned controls. Conditioned rabbits received 80 trace conditioning trials daily until reaching a criterion of 80% conditioned responses in a session. Hippocampal slices were prepared 1 or 24 h after reaching criterion (for trace-conditioned animals) or after a final unpaired stimulus session (for pseudoconditioned animals); naive animals were untrained. Both somatic and dendritic field potentials were recorded in response to various stimulus durations. Recording and data reduction were performed blind to the conditioning state of the rabbit. The excitatory postsynaptic potential slope was greater in slices prepared from trace-conditioned animals killed 1 h after conditioning than in naive and pseudoconditioned controls (repeated-measures analysis of variance, F = 4.250, P < 0.05). Associative learning specifically enhanced synaptic transmission between CA3 and CA1 immediately after training. This effect was not evident in the population field potential measured 24 h later.
Isoflurane Attenuates Resonant Responses of Auditory Thalamic Neurons
Authors: Tennigkeit Frank , Ries Craig R. , Schwarz Dietrich W. F. , Puil Ernest
Published: December 2017

Tennigkeit, Frank, Craig R. Ries, Dietrich W. F. Schwarz, and Ernest Puil. Isoflurane attenuates resonant responses of auditory thalamic neurons. J. Neurophysiol. 78: 591–596, 1997. In thalamocortical neurons, sensory signals are transformed differently during various states of consciousness. We investigated the effects of a general anesthetic, isoflurane, on the frequency responses of neurons in the ventral medial geniculate body, the primary nucleus of the auditory thalamus. Using slice preparations, whole cell current-clamp recording techniques, and frequency-domain analyses with oscillatory inputs, we observed a resonance in the hyperpolarized voltage range, implying a frequency preference near 1 Hz in the subthreshold frequency responses of medial geniculate neurons. As in other thalamocortical neurons, an interaction of a T-type Ca2+ current with passive membrane properties generates the resonant responses. The frequency preference shapes the input-output signal transformation, coupling oscillatory inputs at preferred frequencies to firing. Thus resonance may contribute to the rhythmic synchronization of the output to the cortex. In a concentration range of 0.5–3%, isoflurane application reversibly decreased the resonant responses of medial geniculate neurons. Throughout the subthreshold voltage range, it reduced impedance at frequencies <10 Hz. At depolarized potentials near −60 mV, isoflurane reduced the low-pass filter selectivity of the neuron membrane. At rest near −70 mV or at hyperpolarized potentials, isoflurane had a greater effect on resonance (centered at ∼1 Hz), reducing the peak impedance more than the magnitudes at other frequencies. At concentrations of ≥2%, isoflurane completely blocked the resonance peak, thereby imposing low-pass characteristics of poor quality throughout the subthreshold voltage range. Application of isoflurane reversibly increased membrane conductance and the current threshold for firing evoked by depolarizing pulses from potentials between −60 and −90 mV. The neurons discharged in a tonic pattern on depolarization from about −60 mV and in a phasic (burst) mode from potentials negative to about −70 mV. An increase in current amplitude compensated the suppression of tonic firing much more readily than that of the burst firing on a low-threshold Ca2+ spike. Although a reduction in T-type Ca2+ channel activationmay occur during isoflurane application, the depression of resonance is consistent with an interaction of a greatly increased leak conductance with the low-threshold Ca2+ current and the membrane capacitance. In the intact animal, this would tend to disrupt synchronized neural oscillations and the transfer of auditory information.
Task-Dependent Representations in Rat Hippocampal Place Neurons
Authors: Kobayashi Tsuneyuki , Nishijo Hisao , Fukuda Masaji , Bures Jan , Ono Taketoshi
Published: December 2017

Kobayashi, Tsuneyuki, Hisao Nishijo, Masaji Fukuda, Jan Bures, and Taketoshi Ono. Task-dependent representations in rat hippocampal place neurons. J. Neurophysiol. 78: 597–613, 1997. It is suggested that the hippocampal formation is essential to spatial representations by flexible encoding of diverse information during navigation, which includes not only externally generated sensory information such as visual and auditory sensation but also ideothetic information concerning locomotion (i.e., internally generated information such as proprioceptive and vestibular sensation) as well as information concerning reward. In the present study, we investigated how various types of information are represented in the hippocampal formation, by recording hippocampal complex-spike cells from rats that performed three types of place learning tasks in a circular open field with the use of intracranial self-stimulation as reward. The intracranial self-stimulation reward was delivered in the following three contexts: if the rat 1) entered an experimenter-determined reward place within the open field, and this place was randomly varied in sequential trials; 2) entered two specific places, one within and one outside the place field (an area identified by change in activity of a place neuron); or 3) entered an experimenter-specified place outside the place field. Because the behavioral trails during navigation were more constant in the second task than in the first task, ideothetic information concerning locomotion was more relevant to acquiring reward in the second task than in the first task. Of 43 complex-spike cells recorded, 37 displayed place fields under the first task. Of these 37 place neurons, 34 also had significant reward correlates only inside the place field. Although reward and place correlates of the place neuron activity did not change between the first and second tasks, neuronal correlates to behavioral variables for locomotion such as movement speed, direction, and turning angle significantly increased in the second task. Furthermore, 6 of 31 place neurons tested with the third task, in which the reward place was located outside the original place field, shifted place fields. The results indicated that neuronal correlates of most place neurons flexibly increased their sensitivity to relevant information in a given context and environment, and some place neurons changed the place field per se with place reward association. These results suggest two strategies for how hippocampal neurons incorporate an incredible variety of perceptions into a unified representation of the environment: through flexible use of information and the creation of new representations.
Spinal Strychnine Alters Response Properties of Nociceptive-Specific Neurons in Rat Medial Thalamus
Authors: Sherman Stephen E. , Luo Lei , Dostrovsky Jonathan O.
Published: December 2017

Sherman, Stephen E., Lei Luo, and Jonathan O. Dostrovsky. Spinal strychnine alters response properties of nociceptive-specific neurons in rat medial thalamus. J. Neurophysiol. 78: 628–637, 1997. Experiments in both conscious and anesthetized animals indicate that intrathecal (i.t.) strychnine (STR; glycine receptor antagonist) produces acute, reversible allodynia, as evidenced by inappropriate behavioral and autonomic responses to cutaneous tactile stimuli. Although STR is known to produce disinhibition of afferent input to the spinal cord, changes in spinal reflexes cannot fully explain the complex behaviors observed following i.t. STR. Which supraspinal sites are involved in STR-dependent allodynia and how this abnormal somatosensory message is relayed to these sites remain to be determined. The medial thalamus contains many nociceptive-specific (NS) neurons and is believed to be involved in mediating the affective-motivational aspects of pain. It is thus important to determine whether spinally administered STR elicits changes in the responses of medial thalamic NS neurons. Extracellular single-unit recordings were conducted in urethan-anesthetized rats (290–490 g). A detailed characterization of 20 thalamic NS units (1 per rat; 2 in 1 case) was conducted before and immediately after i.t. STR (40 μg). Initially, all of the units in this study were classified as NS, because they were excited by noxious pinch but not by innocuous tactile stimuli. After i.t. STR, all (formerly NS) units exhibited significant responses to innocuous tactile stimuli (brush and/or air jet) applied to lumbar or sacral dermatomes. This effect of STR on thalamic NS neurons was acute and reversible. The majority of units (11 of 20) also exhibited an increase in spontaneous firing rate. Although the complete pinch receptive field (RF) could not be determined for all units, the available data indicate that the RFs for brush stimulation after i.t. STR were substantially different from the pre-STR pinch RFs for all but three units. The same i.t. STR injection that caused the observed changes in medial thalamus also produced allodynia, in the form of brush-evoked cardiovascular or motor responses, in 18 of the 19 rats. The ability of NS cells in medial thalamus to respond to tactile input after i.t. STR suggests that the STR lowers the threshold of nociceptive neurons that project directly and/or indirectly to medial thalamus. These observations suggest that ascending nociceptive pathways and medial thalamic structures contribute to the expression of STR-dependent allodynia.
Epaxial and Limb Muscle Activity During Swimming and Terrestrial Stepping in the Adult Newt,Pleurodeles waltl
Authors: Delvolvé Isabelle , Bem Tiaza , Cabelguen Jean-Marie
Published: December 2017

Delvolvé, Isabelle, Tiaza Bem, and Jean-Marie Cabelguen. Epaxial and limb muscle activity during swimming and terrestrial stepping in the adult newt, Pleurodeles waltl. J. Neurophysiol. 78: 638–650, 1997. We have investigated the patterns of activation of epaxial musculature during both swimming and overground stepping in an adult newt ( Pleurodeles waltl) with the use of electromyographic (EMG) recordings from different sites of the myomeric muscle dorsalis trunci along the body axis. The locomotor patterns of some limb muscles have also been investigated. During swimming, the epaxial myomeres are rhythmically active, with a strict alternation between opposite myomeres located at the same longitudinal site. The pattern of intersegmental coordination consists of three successively initiated waves of EMG activity passing posteriorly along the anterior trunk, the midtrunk, and the posterior trunk, respectively. Swimming is also characterized by a tonic activation of forelimb (dorsalis scapulae and extensor ulnae) and hindlimb (puboischiotibialis and puboischiofemoralis internus) muscles and a rhythmic activation of muscles (latissimus dorsi and caudofemoralis) acting both on limb and body axis. The latter matched the activation pattern of epaxial myomeres at the similar vertebral level. During overground stepping, the midtrunk myomeres express single synchronous bursts whereas the myomeres of the anterior trunk and those of the posterior trunk display a double bursting pattern in the form of two waves of EMG activity propagating in opposite directions. During overground stepping, the limb muscles and muscles acting on both limb and body axis were found to be rhythmically active and usually displayed a double bursting pattern. The main conclusion of this investigation is that the patterns of intersegmental coordination during both swimming and overground stepping in the adult newt are related to the presence of limbs and that they can be considered as hybrid lampreylike patterns. Thus it is hypothesized that, in newt, a chain of coupled segmental oscillatory networks, similar to that which constitutes the central pattern generator (CPG) for swimming in the lamprey, can account for both trunk motor patterns if it is influenced by limb CPGs in a way depending on the locomotor mode. During swimming, the segmental networks located close to the girdles receive extra tonic excitation coming from the limb CPGs, whereas during stepping, the axial CPGs are entrained to some extent by the limb oscillators.
Biphasic Modulation of Spinal Nociceptive Transmission From the Medullary Raphe Nuclei in the Rat
Authors: Zhuo M. , Gebhart G. F.
Published: December 2017

Zhuo, M. and G. F. Gebhart. Biphasic modulation of spinal nociceptive transmission from the medullary raphe nuclei in the rat. J. Neurophysiol. 78: 746–758, 1997. The modulatory effects of electrical and chemical (glutamate) stimulation in the rostral ventromedial medulla (RVM) on spinal nociceptive transmission and a spinal nociceptive reflex were studied in rats. Electrical stimulation at a total 86 sites in the RVM in the medial raphe nuclei ( n = 54) and adjacent gigantocellular areas ( n = 32) produced biphasic (facilitatory and inhibitory, n = 43) or only inhibitory ( n = 43) modulation of the tail-flick (TF) reflex. At these 43 biphasic sites in the RVM, facilitation of the TF reflex was produced at low intensities of stimulation (5–25 μA) and inhibition was produced at greater intensities of stimulation (50–200 μA). At 43 sites in the RVM, electrical stimulation only produced intensity-dependent inhibition of the TF reflex. Activation of cell bodies in the RVM by glutamate microinjection reproduced the biphasic modulatory effects of electrical stimulation. At biphasic sites previously characterized by electrical stimulation, glutamate at a low concentration (5 nmol) produced facilitation of the TF reflex; a greater concentration (50 nmol) only inhibited the TF reflex. In electrophysiological experiments, electrical stimulation at 62 sites in the RVM produced biphasic ( n = 26), only inhibitory ( n = 26), or only facilitatory ( n = 10) modulation of responses of lumbar spinal dorsal horn neurons to noxious cutaneous thermal (50°C) or mechanical (75.9 g) stimulation. Facilitatory effects were produced at lesser intensities of stimulation and inhibitory effects were produced at greater intensities of stimulation. The apparent latencies to stimulation-produced facilitation and inhibition, determined with the use of a cumulative sum method and bin-by-bin analysis of spinal neuron responses to noxious thermal stimulation of the skin, were 231 and 90 ms, respectively. The spinal pathways conveying descending facilitatory and inhibitory influences were found to be different. Descending facilitatory influences on the TF reflex were conveyed in ventral/ventrolateral funiculi, whereas inhibitory influences were conveyed in dorsolateral funiculi. The results indicate that descending inhibitory and facilitatory influences can be simultaneously engaged throughout the RVM, including nucleus raphe magnus, and that such influences are conveyed in different spinalfuniculi.
Modulation of Ca2+Currents by Various G Protein-Coupled Receptors in Sympathetic Neurons of Male Rat Pelvic Ganglia
Authors: Zhu Yu , Yakel Jerrel L.
Published: December 2017

Zhu, Yu and Jerrel L. Yakel. Modulation of Ca2+currents by various G protein-coupled receptors in sympathetic neurons of male rat pelvic ganglia. J. Neurophysiol. 78: 780–789, 1997. The modulation of voltage-gated calcium (Ca2+) channels by various G protein-coupled receptor pathways was investigated in sympathetic neurons of the male rat major pelvic ganglion (MPG). Standard whole cell patch-clamp recording techniques were used to record Ca2+currents from acutely dissociated neurons. The activation of muscarinic receptors, which uses a G protein pathway that was not blocked by either pertussis toxin (PTX) or cholera toxin (CTX), inhibited both N-type and L-type Ca2+channels. The activation of α2noradrenergic receptors with the selective agonist UK14304, which used primarily a PTX-sensitive G protein pathway, inhibited only N-type Ca2+channels. The activation ofvasoactive intestinal polypeptide (VIP) receptors, which used a CTX-sensitive G protein pathway, also inhibited only N-type Ca2+channels. UK14304 and VIP induced a bell-shaped inhibition of the Ca2+current with a peak inhibition at around +10 mV and decreasing inhibition at more positive potentials. In contrast, the muscarine-induced Ca2+current inhibition was not bell shaped and was more prominent at more positive potentials. Furthermore, a large depolarization, which relieved the current inhibition by UK14304 and VIP, did not relieve the inhibition by muscarine. Besides inhibiting the Ca2+current, UK14304 and VIP also slowed the activation kinetics, an effect not seen with muscarine. Replacing external Ca2+with Ba2+and replacing internal ethylene glycol-bis(β-aminoethyl ether)- N,N,N′,N′-tetraacetic acid (EGTA) with high bis-( o-aminophenoxy)- N,N,N′,N′-tetraacetic acid (BAPTA) completely blocked the inhibitory effect of muscarine. However, the inhibitory effects of both UK14304 and VIP were unaffected under these conditions. Surprisingly, the facilitation of the Ca2+current was eliminated under these strong calcium-buffering conditions. The activation of protein kinase C (PKC) with phorbol 12-myristate 13-acetate (PMA) increases the amplitude of the Ca2+current, diminishes facilitation, and reduces the inhibition of this current by UK14304 and VIP. However, PKC activation did not reduce the muscarine-induced Ca2+current inhibition. In summary, our data suggest that muscarine uses a mechanism different from UK14304 and VIP to modulate the N-type Ca2+channels in sympathetic neurons of the MPG. Although VIP and UK14304 use different G protein pathways, these two different pathways most likely converge downstream to compete for the same target site on the N-type Ca2+channels.
Feeding Stimulants Activate an Identified Dopaminergic Interneuron That Induces the Feeding Motor Program inHelisoma
Authors: Quinlan E. M. , Arnett B. C. , Murphy A. D.
Published: December 2017

Quinlan, E. M., B. C. Arnett, and A. D. Murphy. Feeding stimulants activate an identified dopaminergic interneuron that induces the feeding motor program in Helisoma. J. Neurophysiol. 78: 812–824, 1997. The neurotransmitter dopamine is shown to play a fundamental role in the generation of the feeding motor pattern and resultant feeding behavior in Helisoma. Application of exogenous dopamine triggered the fictive feeding motor pattern in the isolated CNS and triggered feeding movements in semi-intact preparations. Application of feeding stimulants to the oral cavity excited the putatively dopaminergic buccal interneuron N1a, and depolarization of interneuron N1a triggered the production of the fictive feeding motor pattern. The ability of dopamine superfusion and of interneuron N1a stimulation to activate the fictive feeding motor pattern was blocked by the dopamine antagonist sulpiride. The phase of the fictive feeding motor pattern was reset by brief hyperpolarization of interneuron N1a, demonstrating that interneuron N1a is an integral component of the buccal central pattern generator (CPG). During spontaneous fictive feeding patterns, prolonged hyperpolarizations of interneuron N1a inhibited the production of patterned activity. Exogenous dopamine maintained the fictive feeding motor pattern in the absence of interneuron N1a activity. Interneuron N1a was labeled by the formaldehyde-glutaraldehyde histochemical technique, which is indicative of the presence of dopamine in mollusks. These data suggest that interneuron N1a is an endogenous source of the neuromodulator dopamine, intrinsic to the buccal CPG, and that interneuron N1a has a prominent role in the sensory-motor integration triggering the consummatory response.
Five Sources of a Dorsal Root Potential: Their Interactions and Origins in the Superficial Dorsal Horn
Authors: Wall Patrick D. , Lidierth Malcolm
Published: December 2017

Wall, Patrick D. and Malcolm Lidierth. Five sources of a dorsal root potential: their interactions and origins in the superficial dorsal horn. J. Neurophysiol. 78: 860–871, 1997. The dorsal root potential (DRP) was measured on the lumbar dorsal roots of urethan anesthetized rats and evoked by stimulation of five separate inputs. In some experiments, the dorsal cord potential was recorded simultaneously. Stimulation of the L3 dorsal root produced a DRP on the L2 dorsal root containing the six components observed in the cat including the prolonged negative wave (DRP V of Lloyd 1952 ). A single shock to the myelinated fibers in the sural nerve produced a DRP on the L6 dorsal root after the arrival in the cord of the afferent volley. The shape of this DRP was similar to that produced by dorsal root stimulation. Repetitive stimulation of the myelinated fibers in the gastrocnemius nerve also produced a prolonged negative DRP on the L6 dorsal root. When a single stimulus (<5 μA; 200 μs) was applied through a microelectrode to the superficial Lissauer Tract (LT) at the border of the L2 and L3 spinal segments, a characteristic prolonged negative DRP (LT-DRP) began on the L2 dorsal root after some 15 ms. Stimulation of the LT evoked DRPs bilaterally. Recordings on nearby dorsal roots showed this DRP to be unaccompanied by stimulation of afferent fibers in those roots. The LT-DRP was unaffected by neonatal capsaicin treatment that destroyed most unmyelinated fibers. Measurements of myelinated fiber terminal excitability to microstimulation showed that the LT-DRP was accompanied by primary afferent depolarization. Repetitive stimulation through a microelectrode in sensorimotor cortex provoked a prolonged and delayed negative DRP (recorded L2–L4). Stimulation in the cortical arm area and recording on cervical dorsal roots showed that the DRP was evoked more from motor areas than sensory areas of cortex. Interactions were observed between the LT-DRP and that evoked from the sural or gastrocnemius nerves or motor cortex. The LT-DRP was inhibited by preceding stimulation of the other three sources but LT stimulation did not inhibit DRPs evoked from sural or gastrocnemius nerves on the L6 dorsal root or from motor cortex on the L3 root. However, LT stimulation did inhibit the DRP evoked by a subsequent Lissaeur tract stimulus. Recordings were made from superficial dorsal horn neurons. Covergence of input from LT sural, and gastrocnemius nerves and cortex was observed. Spike-triggered averaging was used to examine the relationship between the ongoing discharge of superficial dorsal horn neurons and the spontaneous DRP. The discharge of 81% of LT responsive cells was correlated with the DRP.
Mechanisms of Onset Responses in Octopus Cells of the Cochlear Nucleus: Implications of a Model
Authors: Cai Yidao , Walsh Edward J. , McGee JoAnn
Published: December 2017

Cai, Yidao, Edward J. Walsh, and JoAnn McGee. Mechanisms of onset responses in octopus cells of the cochlear nucleus: implications of a model. J. Neurophysiol. 78: 872–883, 1997. The octopus cells of the posteroventral cochlear nucleus receive inputs from auditory-nerve fibers and form one of the major ascending auditory pathways. They respond to acoustic and electrical stimulation transiently and are believed to carry temporal information in the precise timing of their action potentials. The mechanism whereby onset responses are generated is not clear. Proposals aimed at elucidating the mechanism range from neural circuitry and/or inhibition, “depolarization block” (or inactivation of Na+ channels), and the involvement of a 4-aminopyridine (4-AP)–sensitive, low-threshold channel (KLT). In the present study, we used a compartment model to investigate possible mechanisms. The model cell contains a soma, an axon, and four passive dendrites. Four kinds of ionic channels were included in the soma compartment: the Hodgkin-Huxley–like Na+ and K+ channels, a 4-AP–sensitive, low-threshold channel, KLT, and a Cs+-sensitive, hyperpolarization-activated inward rectifier, I h . DC currents and half-wave–rectified sinewaves were used as stimuli. Our results showed that an onset response can be generated in the absence of neuronal circuitry of any form, thus suggesting that the onset response in octopus cells is regulated intrinsically. Among the many factors involved, low-input impedance, partly contributed by I h , appears to be essential to the basic onset response pattern; also, the KLT conductance plays a major role, whereas the inactivation of Na+ channels probably plays only a secondary role. The dynamics of I h also can modify the response pattern, but due to its slow kinetics, its role is probably limited to longer-term regulation under the conditions simulated in this study.
Voltage-Dependent Gating of ATP-Activated Channels in PC12 Cells
Authors: Nakazawa Ken , Liu Min , Inoue Kazuhide , Ohno Yasuo
Published: December 2017

Nakazawa, Ken, Min Liu, Kazuhide Inoue, and Yasuo Ohno. Voltage-dependent gating of ATP-activated channels in PC12 cells. J. Neurophysiol. 78: 884–890, 1997. The possibility that P2X receptors exhibit voltage-dependent gating in a similar manner to nicotinic receptors was investigated in rat pheochromocytoma cells with the use of whole cell voltage-clamp techniques. In the presence of extracellular ATP, slowly activating inward currents were elicited by stepping from −50 mV to potentials more negative than −80 mV; these currents had a time constant of ∼60 ms at −120 mV. This slowly activating component (as a fraction of the total ATP-induced current) increased with membrane hyperpolarization from −80 to −100 mV and was much increased when depolarizing prepulses were applied, although the time constant of activation was not altered by depolarizations. The fraction of the slowly activating current and its time constant were decreased as the ATP concentration was increased from 10 to 300 μM. Thus it has been demonstrated that voltage-dependent gating of ATP-activated channels does occur in PC12 cells, and that this gating is modified by agonist concentration. It is possible that such gating may serve as a postsynaptic mechanism to facilitate excitatory neurotransmission by contributing to the inward rectification of the ATP-activated currents.
Dopaminergic Modulation of Excitatory Postsynaptic Currents in Rat Neostriatal Neurons
Authors: Umemiya Masashi , Raymond Lynn A.
Published: December 2017

Umemiya, Masashi and Lynn A. Raymond. Dopaminergic modulation of excitatory postsynaptic currents in rat neostriatal neurons. J. Neurophysiol. 78: 1248–1255, 1997. γ-aminobutyric acid (GABA)-containing medium spiny neurons constitute ∼90% of the neuronal population in the neostriatum (caudate and putamen) and play an important role in motor programming. Cortical glutamatergic afferents provide the main excitatory drive for these neurons, whereas nigral dopaminergic neurons play a crucial role in regulating their activity. To further investigate the mechanisms underlying the dopaminergic modulation of medium spiny neuronal activity, we tested the effect of dopamine receptor agonists on excitatory synaptic transmission recorded from these neurons. Excitatory postsynaptic currents (EPSCs) were evoked by local stimulation and recorded from medium spiny neurons in postnatal rat striatal thin brain slices. Recordings were made using the whole cell patch-clamp technique under voltage clamp and conditions that selected for the α-amino-3-hydroxy-5-methyl-4-isoxazole propionate- and kainate-type glutamate receptor-mediated components of the EPSC. Incubation of slices in 10 μM dopamine resulted in a 33 ± 11% (mean ± SE) decrease in the amplitude of evoked EPSCs, an effect that developed during seconds. The relative variability in amplitude of dopamine's effects on medium spiny neuron EPSCs may reflect activation of different receptor subtypes with opposing effects. In contrast to the results with dopamine, incubation of slices in SKF 38393, a D1-type dopamine receptor selective agonist, resulted in dose-dependent potentiation of the medium spiny neuron EPSC that developed during several minutes. At a concentration of 5 μM, SKF 38393 resulted in a 29 ± 4.5% increase in EPSC amplitude, an effect that was blocked by preincubation with the D1-selective antagonist, SCH 23390 (10 μM). On the other hand, 5 μM SKF 38393 had no apparent effect on medium spiny neuron currents activated by exogenous application of glutamate or kainate. However, because of the inherent limitations of rapid agonist perfusion in the brain slice preparation (caused by slow agonist diffusion and rapid glutamate receptor desensitization) and because of anatomic evidence that colocalizes D1 and glutamate receptors to medium spiny neuron dendrites, our results leave open the possibility that the effect of D1 receptor activation on the EPSC is mediated via modulation of postsynaptic glutamate receptor responsiveness. The significant potentiation by D1 receptor agonists of EPSC amplitude at the cortico-striatal medium spiny synapse that we observed, in part, may underlie the role of D1 receptors in facilitating medium spiny neuronal firing, with implications for understanding regulation of movement.
Properties of a Ca2+-Activated K+Conductance in Acutely Isolated Pyramidal-Like Neurons From the Rat Basolateral Amygdaloid Complex
Authors: Meis S. , Pape H.-C.
Published: December 2017

Meis, S. and H.-C. Pape. Properties of a Ca2+-activated K+conductance in acutely isolated pyramidal-like neurons from the rat basolateral amygdaloid complex. J. Neurophysiol. 78: 1256–1262, 1997. A calcium (Ca2+)-activated potassium (K+) conductance was studied in large pyramidal-like neurons acutely dissociated from the rat basolateral amygdaloid complex. Neurons were immunoreactive to anti-α(913–926), a sequence-directed antibody directed against the pore-forming α-subunit of the BKCachannel, also termed slo. Whole cell current-voltage ( I-V) relationships obtained on application of slow (46.7 mV/s) voltage ramps from −110 to +100 mV were N shaped positive to −30 mV. Maximal current activation occurred at +9.8 ± 2.7 (SE) mV, with a mean current density of 404.8 ± 25.0 pA/pF. Substitution of extracellular Ca2+with manganese (Mn2+), or with magnesium (Mg2+) and addition of 5 mM ethyleneglycol-bis(β-aminoethylether)- N,N,N′,N′-tetraacetic acid, abolished the N-shaped I-V relationship with a reduction in maximal outward current to 15.3 ± 2.3% of the control value. The Ca2+-sensitive K+current component, as revealed by voltage step protocols, activated at depolarizations positive to −30 mV with a slow time course (time constant 430.7 ± 78.6 ms). The current was reduced by 80.4 ± 4.6% through 1 mM tetraethyammonium chloride and by 66.8 ± 3.4% through 100 nM iberiotoxin, whereas apamin up to 1 μM had no effect. It is concluded that pyramidal-like neurons of the basolateral amygdaloid complex possess BKCachannels and the corresponding macroscopic Ca2+-sensitive K+conductance, activation of which will substantially contribute to the Ca2+-dependent regulation of electrogenic behavior in these neurons.
Spinal Cord Coordination of Hindlimb Movements in the Turtle: Intralimb Temporal Relationships During Scratching and Swimming
Authors: Field Edelle C. , Stein Paul S. G.
Published: December 2017

Field, Edelle C. and Paul S. G. Stein. Spinal cord coordination of hindlimb movements in the turtle: intralimb temporal relationships during scratching and swimming. J. Neurophysiol. 78: 1394–1403, 1997. Spinal cord neuronal circuits generate motor neuron activity patterns responsible for rhythmic hindlimb behaviors such as scratching and swimming. Kinematic analyses of limb movements generated by this motor neuron output reveal important characteristics of these behaviors. Intralimb kinematics of the turtle hindlimb were characterized during five distinct rhythmic forms of behavior: three forms of scratching and two forms of swimming. In each movement cycle for each form, the angles of the hip and knee joints were measured as well as the timing of a behavioral event, e.g., rub onset in scratching or powerstroke onset in swimming. There were distinct differences between the kinematics of different forms of the same behavior, e.g., rostral scratch versus pocket scratch. In contrast, there were striking similarities between forms of different behaviors, e.g., rostral scratch versus forward swimming. For each form of behavior there was a characteristic angular position of the hip at the onset of each behavioral event (rub or powerstroke). The phase of the onset of knee extension within the hip position cycle occurred while the hip was flexing in the rostral scratch and forward swim and while the hip was extending in the pocket scratch, caudal scratch, and back-paddling form of swimming. The phase of the onset of the behavioral event was not statistically different between rostral scratch and forward swim; nor was it different between pocket scratch and caudal scratch. These observations of similarities at the movement level support the suggestion that further similarities, such as shared spinal circuitry, may be present at the neural circuitry level as well.