bluuebunny/crossref_metadata_2025 huggingface dataset:
Paraventricular neuron chemosensitivity and activity related to blood pressure control in emotional behavior
Authors: Nakamura K. , Ono T. , Fukuda M. , Uwano T.
Published: December 2017

1. Unit activity in the paraventricular nucleus (PVN) and blood pressure (BP) of the rat were recorded during discrimination learning of cue tone (CTS+) predicting reward [glucose and intracranial self stimulation (ICSS)], and cue tone (CTS-) predicting aversion (electric shock or tail pinch). Adrenergic systems in the PVN were investigated by electrophoretic application of norepinephrine (NE), and by electrophoretic application or direct microinjection of its antagonists (prazosin, yohimbine, and propranolol). 2. Of 65 PVN neurons analyzed, 35 responded during CTS learning in one or more phases of an operant task. Of these, activity of 20 neurons was increased nondiscriminatively by CTS+ and CTS-, and reward and aversion. In parallel with these neuronal activity increases, BP (systolic, diastolic, and mean) was also increased by both CTS+ and CTS- (10-35 mmHg), and reward and aversion (20-47 mmHg). Both neuronal activity and BP increases during CTS learning were suppressed during extinction. 3. Paraventricular neurons, the activity of which correlated with BP increase during CTS learning, were excited by electrophoretic application of NE and Na+ and fired phasically during inter-trial intervals. Activity increases of these neurons during CTS learning, which was related to BP increase, were blocked by electrophoretically applied prazosin (alpha 1-antagonist), but not by yohimbine (alpha 2-antagonist) or propranolol (beta-antagonist). 4. Direct microinjection of prazosin into the PVN suppressed BP increase during CTS learning. Operant licking for reward was not suppressed by prazosin injection. Microinjection of yohimbine or propranolol into the PVN did not suppress either BP increase during CTS learning or operant licking to obtain reward. 5. These results suggest that afferent alpha 1-adrenergic input to the PVN is important to the central BP control during CTS learning in emotional behavior.
Presynaptic modulation by GABAB receptors of glutamatergic excitation and GABAergic inhibition of neostriatal neurons
Authors: Nisenbaum E. S. , Berger T. W. , Grace A. A.
Published: December 2017

1. The present experiments investigated the effects of gamma-amino-butyric acidB (GABAB) receptor stimulation on the excitatory and inhibitory responses of neostriatal neurons evoked by stimulation of the subcortical white matter in a rat neostriatal slice preparation. 2. Intracellular recordings showed that single-impulse stimulation of the corpus callosum evoked monosynaptic, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-sensitive excitatory postsynaptic potentials (EPSPs) that were attenuated by the GABAB receptor agonist, p-chlorophenyl-GABA (baclofen, 0.5-10 microM) in a concentration-dependent manner. Baclofen also blocked the GABAA-mediated inhibition of neostriatal cell responses, which were revealed by paired-impulse stimulation of the subcortical white matter. Both of these effects persisted in slices in which the anterior cortex was removed, indicating that the site of action for baclofen was intrinsic to the neostriatum. The GABAB antagonist 3-amino-2-hydroxy-2-(4-chlorophenyl)-propanesulfonic acid (saclofen, 250-500 microM) reversed the depressant actions of baclofen on both the excitatory and inhibitory responses of neostriatal cells. 3. Concentrations of baclofen as high as 100 microM, which markedly attenuated EPSP amplitude, did not exert direct effects on resting membrane potential, current-voltage relationship, input resistance, or spike threshold and thus appeared to have no postsynaptic effect on the population of neurons recorded. 4. These results indicate that, in contrast to other regions of the CNS, the depressant effects of baclofen on glutamate-dependent EPSPs are mediated exclusively through GABAB receptors located presynaptically on the terminals of glutamatergic afferents.(ABSTRACT TRUNCATED AT 250 WORDS)
Organization of sequential typing movements
Authors: Soechting J. F. , Flanders M.
Published: December 2017

1. Experienced touch typists were asked to type words that contained only one or two letters typed by one of the two hands. When a word contained a pair of letters typed by one hand, the letters could be consecutive, or there could be one, two, or three intervening letters typed with the other hand. 2. We studied cases in which pairs of letters were either identical, different but typed with the same finger, or typed with two different fingers on the same hand. 3. Translational and rotational motion of the fingers and wrist was computed optoelectronically from the location of reflective markers on the hands. Finger and wrist motion recorded when subjects typed pairs of letters was compared with the motion recorded when the subject typed either letter in isolation. 4. When the subject typed the same letter consecutively, or separated by intervening letters, the second keystroke began only after the first key had been pressed. The same result was obtained when the second letter was not identical but was typed with the same finger. Up to the time of the first keypress, the initial keystroke kinematics were identical to those for that letter typed in isolation. 5. When the second letter in a pair was typed with the use of a different finger, the initial focal movement (wrist and finger striking the key) was unaffected up to the time of initial keypress. However, the second finger could begin to move toward the second key shortly before the initial keypress, and therefore the corollary movements normally involved in the initial keystroke were affected. 6. These results indicate that typing movements are executed primarily in a serial fashion, letter by letter. There can be some overlap between consecutive keystrokes only if they are executed with different fingers. 7. Words in which two letters typed with one hand were separated by three letters typed with the other hand provided subjects the opportunity to initiate the second keystroke at a range of times after the first keypress. 8. When the second letter differed from the first, subjects always returned to the home position after the first keypress and initiated the second keystroke with a normal latency. However, when the second letter was the same as the first letter, subjects sometimes suppressed the return to the home position after the first keystroke and maintained their finger poised over the key. 9. Thus keystrokes of one hand are best described as being executed sequentially. However, the findings presented here also indicate that movement planning encompasses strings of letters.
gamma-Aminobutyric acid-induced response in rat dissociated paratracheal ganglion cells
Authors: Itabashi S. , Aibara K. , Sasaki H. , Akaike N.
Published: December 2017

1. The pharmacologic properties of gamma-aminobutyric acid (GABA)-induced Cl- current (ICl) were studied in the paratracheal ganglion cells freshly dissociated from 7- to 10-day-old rat trachea in a whole-cell recording mode by the use of a conventional patch-clamp technique. 2. GABA- and muscimol-induced currents increased sigmoidally in a concentration-dependent manner, and both currents reversed at approximately -3 mV, which was close to the Cl- equilibrium potential (ECl). 3. Strychnine (STR) at low concentration and bicuculline (BIC) inhibited GABA response competitively, whereas STR at the higher concentrations, benzylpenicillin (PCG), or picrotoxin (PTX) inhibited noncompetitively. Inhibition of GABA response by PCG but not other antagonists was voltage dependent, indicating that PCG acts as a Cl- channel blocker. 4. The concentration-response curve of pentobarbital sodium (PB)-induced ICl was bell shaped. At concentrations higher than 10(-3) M, both the peak and plateau currents decreased, and a transient "hump" current appeared immediately after washing out PB. In the presence of PB, the concentration-response curve of GABA shifted toward left without changing the maximum response. 5. Although diazepam (DZP) at concentration used did not induce a response, it potentiated the GABA response in a concentration-dependent manner between 10(-8) and 10(-6) M. DZP also caused a parallel shift toward left in the concentration-response curve of GABA. 6. PB or DZP further enhanced the GABA response in the presence of the other agent. 7. It is concluded that the properties of GABAA receptors in the paratracheal ganglion cells are essentially similar to those reported in other preparations.
Neural interaction in cat primary auditory cortex. Dependence on recording depth, electrode separation, and age
Authors: Eggermont J. J.
Published: December 2017

1. Neural activity was recorded with two independent electrodes separated by 0.5-2 mm, aligned in parallel, and advanced perpendicular to the surface of the cat auditory cortex. For smaller separations a solid-state multielectrode array with interelectrode distances of 125 microns was used. The difference in recording depths for the two independently movable electrodes was never more than 100 microns; the electrode contacts of the multielectrode array were at the same depth. Thus the correlation studies dominantly explored horizontal interactions. 2. Out of 995 neuron pairs recorded, 478 represented pairs of single units, whereas the other pairs were contaminated with 5-10% misclassified spikes. Only the single-unit pairs were further analyzed. Of those pairs, 338 showed a clear correlation peak, and in 329 of these the peak heights were exceeding the Z > 4 significance level (P < 0.0001). Two hundred fifty-two of the significant correlograms (53% of total) could be attributed to common input; the remaining (16% of total) were indicative of unilateral excitation. For the 181 single-electrode pairs the percentage of unilateral excitation pairs (42%) was about the same as the percentage of common input pairs (38%). For the 297 dual-electrode pairs all but one of the 184 significant correlations were indicative of common input. No correlograms indicative of inhibition were found. 3. The correlograms with clear peaks were classified into three types: narrow (n = 40), mixed (n = 77), and broad (n = 221). Narrow and mixed types were with two exceptions found only for single-electrode pairs; broad types were found for single- and dual-electrode pairs. Narrow-type correlograms were in majority of the unilateral excitation type. Correlograms were calculated both for 1-ms binwidths (50-ms lead/lag time) and for 10-ms binwidth (500-ms lead/lag time). The correlograms were characterized by four parameters; the half width of the central peak, the peak correlation coefficient, the association index, and for unilateral excitation cases also by the effectiveness. 4. Across all three correlogram types the half width of the correlation peaks was significantly smaller for single-electrode pairs (mean, 27 ms) than for dual-electrode pairs (mean, 42 ms). For broad-type correlograms only, the mean half widths were not significantly different between single- and dual-electrode pairs. 5. The correlation coefficients (1-ms bin correlograms) were significantly larger for single-electrode pairs (mean, 0.038) than for dual-electrode pairs (mean, 0.011). The same was found for the 10-ms binwidth correlograms.(ABSTRACT TRUNCATED AT 400 WORDS)
Inactivation of the DSCF area of the auditory cortex with muscimol disrupts frequency discrimination in the mustached bat
Authors: Riquimaroux H. , Gaioni S. J. , Suga N.
Published: December 2017

1. The Jamaican mustached bat uses a biosonar signal (pulse) with eight major components: four harmonics each consisting of a long constant frequency (CF1-4) component followed by a short frequency-modulated (FM1-4) component. While flying, the bat adjusts the frequency of its pulse so as to maintain the CF2 of the Doppler-shifted echo at a frequency to which its cochlea is very sharply tuned. This Doppler shift (DS) compensation likely is mediated or influenced by the Doppler-shifted CF (DSCF) processing area of the primary auditory cortex, which only represents frequencies in the range of echo CF2s (60.6 to 62.3 kHz when the "resting" frequency of the CF2 is 61.0 kHz). 2. We trained four bats to discriminate between different trains of paired tone bursts that mimicked a bat's pulse CF2 and the accompanying echo CF2. The frequency of these CF2s ranged between 61.0 and 64.0 kHz. A discriminated shock avoidance procedure response was employed using a leg flexion. For one stimulus, the S+, the pulse and echo CF2s were the same frequency (delta f = 0, i.e., no Doppler shift). A leg flexion during the S+ turned off both the S+ and the scheduled shock. For a second stimulus, the S-, the echo CF2 was 0.05, 0.1, 0.3, 0.5, or 2.0 kHz higher than the pulse CF2. A delta f of 0.05 kHz was a frequency difference of 0.08%. No shock followed the S-, and leg flexions had no consequences. Correct responses consisted of a leg flexion during the S+ and no flexion during the S-; these responses were added together to compute the percentage of correct responses. When a bat correctly responded at better than 75% for all the delta f s, muscimol, a potent agonist of gamma-aminobutyric acid, was bilaterally applied to inactivate the DSCF area. Performance on each delta f discrimination was then measured. 3. Initial attempts to condition the bats to flex their legs to the CF tones mimicking part of the natural pulses and echoes failed. When broad-band noise bursts were substituted, however, the conditioned response was rapidly established. The noise band-width was gradually reduced and then replaced with the CF tones. Discrimination training with the tone burst trains then commenced. Throughout this procedure, the bats maintained their responding to the stimuli. The bats typically required approximately 20-30 sessions to perform consistently (> or = 75% correct responses) a discrimination involving a 2 kHz delta f.(ABSTRACT TRUNCATED AT 400 WORDS)
Role of sympathetic innervation in the feline continence process under natural filling conditions
Authors: Vaughan C. W. , Satchell P. M.
Published: December 2017

1. The effect of the sympathetic innervation on the bladder detrusor muscle was assessed in pentobarbitone-anesthetized cats by measuring the changes in bladder wall tension that occurred during sympathetic ganglion blockade after filling the bladder at a natural rate. 2. At a point 60% of the way through the continence process, systemic sympathetic blockade was produced by intravenous trimethaphan, and selective blockade of postganglionic hypogastric nerve activity was produced by application of trimethaphan to the exposed inferior mesenteric ganglia. The level of blockade was monitored with an in-continuity hypogastric nerve recording. 3. During both systemic and selective ganglion blockade, there was an increase in baseline transmural bladder pressure and a decrease in the amplitude of nonmicturating contractions. 4. Although there was no change in the mean level of transmural bladder pressure during either systemic or selective blockade, there was a significant increase in the mean level of bladder wall mechanoreceptor discharge, suggesting that before the blockade sympathoinhibitory effects were greater than sympathoexcitatory effects. 5. Measurement of bladder wall mechanoreceptor discharge before and during ganglion blockade revealed a net sympathoinhibitory influence on the level of bladder wall tension under natural filling conditions. These results confirm that the detrusor muscle of the feline bladder is under both sympathoinhibitory and sympathoexcitatory influences for a significant portion of the continence process.
Responses of trigeminal brain stem neurons and the digastric muscle to tooth-pulp stimulation in awake cats
Authors: Boissonade F. M. , Matthews B.
Published: December 2017

1. Cats were prepared for chronic recording from neurons in pars oralis and pars interpolaris of the trigeminal spinal nucleus. Electrodes were implanted into canine teeth for electrical stimulation and the digastric muscle for recording electromyograms. 2. Recordings were made from the animals when they were awake and unrestrained as well as when they were lightly anesthetized. Some neurons were studied under both conditions. 3. In an awake animal, single tooth-pulp stimuli of 0.1 ms duration and < or = 1 mA intensity produced no aversive behavior. 4. The response of trigeminal brain stem neurons in the awake animal to such stimuli consisted of short (approximately 3 ms)- and long (approximately 25 ms)-latency discharges whose thresholds suggested that they were both due to inputs from fast conducting primary afferent fibers. 5. Light anesthesia reduced the number of impulses in both components and in most cases completely abolished the long-latency component evoked by low-intensity stimuli. The threshold of the short-latency component was little affected by light anesthesia. It is postulated that the short-latency component is mediated by a monosynaptic input from primary afferent fibers and the long-latency component by a polysynaptic input from these same fibers. 6. All neurons that responded to tooth-pulp stimulation had inputs from other orofacial sites both in the awake and lightly anesthetized states. After light anesthesia, these receptive fields were altered in only 3 out of 15 neurons. 7. The majority of neurons (18 out of 20) were not spontaneously active in the awake animal. Spontaneous activity in the other two was reduced by light anesthesia. 8. The threshold of the digastric reflex evoked by tooth-pulp stimulation was not altered by light anesthesia, but the size of the response was reduced. 9. The effects of changing the level of anesthesia from deep to light (i.e., without and with reflex withdrawal to squeezing a paw) on the responses to tooth-pulp stimulation were also studied. Decreasing the anesthetic depth tended to decrease the thresholds and increase the magnitude of both the short- and long-latency neuronal responses and the short-latency digastric response.
Organization of response areas in ferret primary auditory cortex
Authors: Shamma S. A. , Fleshman J. W. , Wiser P. R. , Versnel H.
Published: December 2017

1. We studied the topographic organization of the response areas obtained from single- and multiunit recordings along the isofrequency planes of the primary auditory cortex in the barbiturate-anesthetized ferret. 2. Using a two-tone stimulus, we determined the excitatory and inhibitory portions of the response areas and then parameterized them in terms of an asymmetry index. The index measures the balance of excitatory and inhibitory influences around the best frequency (BF). 3. The sensitivity of responses to the direction of a frequency-modulated (FM) tone was tested and found to correlate strongly with the asymmetry index of the response areas. Specifically, cells with strong inhibition from frequencies above the BF preferred upward sweeps, and those from frequencies below the BF preferred downward sweeps. 4. Responses to spectrally shaped noise were also consistent with the asymmetry of the response areas. For instance, cells that were strongly inhibited by frequencies higher than the BF responded best to stimuli that contained least spectral energy above the BF, i.e., stimuli with the opposite asymmetry. 5. Columnar organization of the response area types was demonstrated in 66 single units from 16 penetrations. Consistent with this finding, it was also shown that response area asymmetry measured from recordings of a cluster of cells corresponded closely with those measured from its single-unit constituents. Thus, in a local region, most cells exhibited similar response area types and other response features, e.g., FM directional sensitivity. 6. The distribution of the asymmetry index values along the isofrequency planes revealed systematic changes in the symmetry of the response areas. At the center, response areas with narrow and symmetric inhibitory sidebands predominated. These gave way to asymmetric inhibition, with high-frequency inhibition (relative to the BF) becoming more effective caudally and low-frequency inhibition more effective rostrally. These response types tended to cluster along repeated bands that paralleled the tonotopic axis. 7. Response features that correlated with the response area types were also mapped along the isofrequency planes. Thus, in four animals, a map of FM directional sensitivity was shown to be superimposed on the response area map. Similarly, it was demonstrated in six animals that the spectral gradient of the most effective noise stimulus varied systematically along the isofrequency planes. 8. One functional implication of the response area organization is that cortical responses encode the locally averaged gradient of the acoustic spectrum by their differential distribution along the isofrequency planes. This enhances the representation of such features as the symmetry of spectral peaks and edges and the spectral envelope.(ABSTRACT TRUNCATED AT 400 WORDS)
Distribution of ionic currents in the soma and growing region of an identified peptidergic neuron in defined culture
Authors: Meyers D. E.
Published: December 2017

1. Somata and lamellipodia of a distinct type of crustacean peptidergic neuron were isolated by severing the connecting neurite. The whole-cell variation of the patch-clamp technique was then used to study the electrical activity and ionic currents of each part. Neurons were enzymatically isolated from the X-organ of Cardisoma carnifex and cultured in defined medium. The neurons studied were recognizable by their large ovoid somata (approximately 35 microns minor diam) and broad, flat lamellipodium regrown from the remaining neurite. These cells are immunopositive against crustacean hyperglycemic hormone (CHH) antisera. Recordings were made 18-30 h after plating. 2. In current-clamp recordings, 10 of 12 lamellipodia fired overshooting action potentials (mean half width = 8.2 +/- 2.9 ms, mean +/- SD), whereas only two of seven somata did so. Spontaneous activity in isolated somata and lamellipodia was rarely encountered. The action potential in isolated lamellipodia has both Na+ and Ca2+ components, whereas the regenerative activity recorded in isolated somata was predominantly Ca(2+)-based. 3. The inward currents examined under voltage clamp consisted of Na current (INa) and Ca current (ICa). Both currents could be resolved in isolated somata and lamellipodia. INa was completely blocked by tetrodotoxin [TTX (1 microM)]. The INa density in lamellipodia was approximately 4-19 times greater than that of the somata from which they had been separated. In contrast, ICa density in lamellipodia was two to five times smaller than that of somata. The properties of ICa were similar in both somata and lamellipodia, with the exception that ICa in lamellipodia did not recover after large depolarizing prepulses. 4. Two types of outward current were readily identified under voltage clamp. These were the transient 4-aminopyridine-sensitive current and the delayed outward current that was partially sensitive to tetraethylammonium ions. The peak potassium current-density ratio for lamellipodia-somata pairs ranged from 0.5 to 1.7 (mean = 1.2, SD +/- 0.6), suggesting that both channel types are distributed relatively evenly over the cell surface. 5. The differences in current density in the different regions did not correlate with the length of the neurite remaining after separation of the soma and lamellipodium. 6. It is concluded that CHH neurons in the early phase of regeneration in primary culture show a distinct pattern of ion channel distribution. These ion channels are present in new membrane < 18 h after formation.(ABSTRACT TRUNCATED AT 400 WORDS)
Discrimination of post- and presynaptic GABAB receptor-mediated responses by tetrahydroaminoacridine in area CA3 of the rat hippocampus
Authors: Lambert N. A. , Wilson W. A.
Published: December 2017

1. The effects of the K+ channel blocker 9-amino-1,2,3,4-tetrahydroacridine (THA) on the actions of baclofen and gamma-aminobutyric acid (GABA) at post- and presynaptic GABAB receptors were studied with whole-cell voltage-clamp recording in area CA3 of rat hippocampal slices. 2. The effect of THA on postsynaptic GABAB receptor-mediated responses was studied in neurons perfused internally with potassium gluconate and guanosine triphosphate (GTP). At a holding potential of -70 mV, the GABAB receptor agonist (+/-)-baclofen (30 microM) induced an outward current and increased membrane conductance. In the presence of the excitatory amino acid receptor antagonists 6,7-dinitroquinoxaline-2,3-dione (DNQX) and (+/-)-2-amino-5-phosphonovalerate (APV), stimulation in stratum pyramidale or proximal stratum radiatum evoked GABAA receptor-mediated, fast monosynaptic inhibitory postsynaptic currents (IPSCs) and GABAB receptor-mediated, late monosynaptic IPSCs. THA (0.3 mM) blocked the baclofen-induced current and conductance increase and GABAB receptor-mediated IPSCs. 3. The effect of THA on presynaptic GABAB receptor-mediated responses was studied in neurons perfused internally with Cs+ and lidocaine N-ethyl bromide (QX-314), which blocked post-synaptic GABAB receptor-mediated responses. Stimulation in the presence of DNQX and APV evoked GABAA receptor-mediated IPSCs; when pairs of stimuli were delivered 200 ms apart the second IPSC was depressed. Baclofen reversibly depressed IPSCs, and partially occluded paired-pulse depression of IPSCs. The GABAB receptor antagonist CGP 35348 (0.5-1.0 mM) reversed baclofen-induced depression of IPSCs and partially blocked paired-pulse depression. Baclofen-induced and paired-pulse depression of IPSCs were not by affected by THA (0.3 mM). 4. Baclofen reversibly decreased the amplitude and frequency of spontaneous monosynaptic IPSCs (sIPSCs). Depression of sIPSCs by baclofen was unchanged by THA. 5. These results indicate that THA blocks the actions of baclofen and GABA at post- but not presynaptic GABAB receptors. We conclude that post- and presynaptic GABAB receptors in area CA3 of the rat hippocampus couple to different effector mechanisms; postsynaptic GABAB receptors activate THA-sensitive K+ channels, and presynaptic GABAB receptors decrease neurotransmitter release through a THA-insensitive mechanism.
Nonlinear stretch reflex interaction during cocontraction
Authors: Carter R. R. , Crago P. E. , Gorman P. H.
Published: December 2017

1. We investigated the role of stretch reflexes in controlling two antagonist muscles acting at the interphalangeal joint in the normal human thumb. Reflex action was compared when either muscle contracted alone and during cocontraction. 2. The total torque of the flexor pollicis longus (FPL) and extensor pollicis longus (EPL) muscles was measured in response to an externally imposed extension of the interphalangeal joint. The initial joint angle and the amplitude of the extension were constant in all experiments, and the preload of the active muscle(s) was varied. Joint torque was measured at the peak of short-latency stretch reflex action during contraction of the FPL alone, contraction of the EPL alone, and during cocontraction. Incremental joint stiffness was calculated as the change in torque divided by the change in angle. 3. Incremental stiffness increased in proportion to the preload torque during single muscle contractions of either the FPL (lengthening disturbances) or the EPL (shortening disturbances). Thus stiffness was not regulated to a constant value in the face of varying loads for either single muscle stretch or release. 4. Incremental stiffness varied across the range of cocontraction levels while the net torque was maintained at approximately 0. Thus net torque alone did not determine the stiffness during cocontraction. 5. The contributions of each muscle to the net intrinsic torque during cocontraction were estimated by scaling the individual muscles' responses so that their sum gave the best fit (in a least-squares sense) to the cocontraction torque before reflex action. The solution is unique because the individual torques have opposite signs, but the stiffnesses add. This gave estimates of the initial torques of both muscles during cocontraction. 6. The contributions of the two muscles during cocontraction were used to estimate the active joint stiffness that would be expected if the two muscles were activated independently to the same levels as in the cocontraction trials. The stiffness measured at the peak of stretch reflex action during cocontraction trials differed from the sum of the stiffnesses of the two muscles when they were contracting alone. At low cocontraction levels, the measured stiffness was less than expected on the basis of summation of the action of the two muscles, whereas at high cocontraction levels, the measured stiffness was greater than expected. This demonstrates that there is nonlinear stretch reflex interaction. That is, reflex action for a pair of antagonists is not simply the linear sum of the reflex actions of the two muscles acting independently.(ABSTRACT TRUNCATED AT 400 WORDS)
Effects of selective attention on spatial form processing in monkey primary and secondary somatosensory cortex
Authors: Hsiao S. S. , O'Shaughnessy D. M. , Johnson K. O.
Published: December 2017

1. The effects of selective attention were studied in SI and SII cortex of a rhesus monkey trained to perform two tasks, a tactile discrimination task and a visual detection task. In the tactile task, a letter was displayed on a video screen in front of the monkey and the animal was rewarded for responding when the raised letter (6.0 mm letter height) scanning across its finger (15 mm/s) matched the letter on the screen. In the visual task, three illuminated squares were displayed on the screen, and the animal was rewarded for detecting when one of the squares dimmed. The neural responses evoked by the raised letters were recorded continuously while the animal's focus of attention was switched back and forth between the two tasks. 2. Significant differences between the discharge rates evoked by raised letters in the two tasks were observed in approximately 50% of neurons in SI cortex and 80% of neurons in SII cortex. The effects in SII cortex were divided between increased (58%) and decreased (22%) rates. In SI cortex only increased rates were observed. 3. The attentional effects were expressed not only as changes in overall neuronal activity but also as modifications of the form of the responses evoked by the letters. 4. Whether attentional effects were observed depended upon the behavioral relevance of individual letters. During brief periods in the tactile task when a behavioral response could not yield a reward (time-out and reward periods) the neuronal responses were not significantly different from the responses evoked by the same letters during the visual task.(ABSTRACT TRUNCATED AT 250 WORDS)
Zinc enhances GABAergic transmission in rat neocortical neurons
Authors: Zhou F. M. , Hablitz J. J.
Published: December 2017

1. Intracellular recordings were made in layer II-III neurons of rat neocortical slices maintained in vitro. The effect of bath application of zinc (50-300 microM) on evoked synaptic activity and passive membrane properties was examined. 2. Excitatory postsynaptic potentials (EPSPs) mediated by N-methyl-D-aspartate (NMDA) and non-NMDA receptors were recorded in response to electrical stimulation. Zinc did not affect either type of EPSP. Resting membrane potential, repetitive firing properties, and input resistance were not altered by zinc. 3. Inhibitory postsynaptic potentials (IPSPs) were enhanced after zinc application. Zinc also induced generation of large amplitude spontaneous gamma-aminobutyric acid-A (GABAA)- and GABAB-mediated IPSPs. Postsynaptic responses to iontophoretically applied GABA were unaffected. In the presence of zinc, GABAergic synaptic potentials could result in generation of action potentials. 4. Directly evoked IPSPs recorded in the presence of the excitatory amino acid receptor blockers 6-cyano-7-nitroquinoxaline-2,3-dione and 2-amino-5-phosphonovaleric acid were enhanced by zinc. Under these conditions spontaneous IPSPs with superimposed action potentials were present. Baclofen, in the presence of zinc, reduced the amplitude of evoked IPSPs. 5. These results indicate that zinc may be an endogenously occurring neuromodulator. Zinc appears to enhance GABAergic IPSPs by increasing the excitability of inhibitory interneurons, thus resulting in increased GABA release.
Stereotypical changes in the pattern and duration of long-term potentiation expressed at postnatal days 11 and 15 in the rat hippocampus
Authors: Jackson P. S. , Suppes T. , Harris K. M.
Published: December 2017

1. Extracellular recordings from hippocampal area CA1 lasting 2-8 h posttetanus were used to evaluate the duration of long-term potentiation (LTP) at two key developmental ages. 2. At day 11 LTP consistently endured for approximately 1 h before declining to baseline by 2.5 h posttetanus. The response could then be repotentiated, and in some cases, the repotentiation lasted longer than the original potentiation. 3. At day 15 two patterns of potentiation were observed. The first pattern was similar to that observed at day 11 in that the potentiation did not persist; however, it did endure for approximately 2-2.5 h before declining to baseline by 4 h posttetanus. In the second pattern the potentiation persisted indefinitely; these responses were monitored for 6-8 h posttetanus. 4. These patterns are similar to the temporal phases of LTP that have been revealed in adult rat hippocampus through pharmacological manipulations. They may reflect developmental changes during which the different cellular mechanisms underlying LTP become sequentially activated. 5. These findings are important for several reasons. First, because the different temporal phases of LTP seem to be added stepwise during development, animals of different ages could be used explicitly to elucidate the underlying cellular mechanisms of these phases in LTP. Second, because LTP is a candidate mechanism for some forms of learning and memory, these results have implications for sequential steps in the ontogeny of learning and memory. Finally, because studies of LTP have used animals of widely varying ages, including these two ages, it is important to consider whether differences in the developmental properties of LTP could influence experimental observations.
The role of brachial muscle spindle signals in assignment of visual direction
Authors: DiZio P. , Lathan C. E. , Lackner J. R.
Published: December 2017

1. In the oculobrachial illusion, a target light attached to the unseen stationary hand is perceived as moving and changing spatial position when illusory motion of the forearm is elicited by brachial muscle vibration. Our goal was to see whether we could induce apparent motion and displacement of two retinally fixed targets in opposite directions by the use of oculobrachial illusions. 2. We vibrated both biceps brachii, generating illusory movements of the two forearms in opposite directions, and measured any associated changes in perceived distance between target lights on the unseen stationary hands. The stability of visual fixation of one of the targets was also measured. 3. The seen distance between the stationary targets increased significantly when vibration induced an illusory increase in felt distance between the hands, both with binocular and monocular viewing. 4. Subjects maintained fixation accuracy equally well during vibration-induced illusory increases in visual target separation and in a no-vibration control condition. Fixation errors were not correlated with the extent or direction of illusory visual separation. 5. These findings indicate that brachial muscle spindle signals can contribute to an independent representation of felt target location in head-centric coordinates that can be interrelated with a visual representation of target location generated by retinal and oculomotor signals. 6. A model of how these representations are interrelated is proposed, and its relation to other intersensory interactions is discussed.
Monosynaptic EPSPs in primate lumbar motoneurons
Authors: Carp J. S.
Published: December 2017

1. Homonymous and heteronymous monosynaptic composite excitatory postsynaptic potentials (EPSPs) were evaluated by intracellular recordings from 89 motoneurons innervating triceps surae (n = 59) and more distal (n = 30) muscles in 14 pentobarbital-anesthetized monkeys (Macaca nemestrina). 2. Homonymous EPSPs were found in all motoneurons tested. The mean values +/- SD for maximum EPSP amplitude of triceps surae motoneurons were 2.5 +/- 1.3, 1.8 +/- 1.3 and 4.5 +/- 2.0 mV for medial gastrocnemius, lateral gastrocnemius, and soleus motoneurons, respectively. Heteronymous EPSPs were almost always smaller than their corresponding homonymous EPSPs. 3. Triceps surae EPSP amplitude was larger in motoneurons with higher input resistance. However, this relationship was weak, suggesting that factors related to input resistance play a limited role in determining the magnitude of the EPSP. 4. The mean ratio +/- SD of the amplitude of the EPSP elicited by combined stimulation of all triceps surae nerves to the amplitude of the algebraic sum of the three individual EPSPs was 0.95 +/- 0.05. This ratio was greater in motoneurons with lower rheobase. 5. Some patterns of synaptic connectivity in the macaque are consistent with previously reported differences between primates and cat (e.g., heteronymous EPSPs elicited by medial gastrocnemius nerve stimulation in soleus motoneurons are small in macaque and other primates but large in cat). However, no overall pattern emerges from a comparison of the similarities and differences in EPSPs among species in which they have been studied (i.e., macaque, baboon, and cat). That is, there are no two species in which EPSP properties are consistently similar to each other, but different from those of the third species.(ABSTRACT TRUNCATED AT 250 WORDS)
Synchronization of motor-unit firings in several human muscles
Authors: De Luca C. J. , Roy A. M. , Erim Z.
Published: December 2017

1. Synchronization of concurrently active motor-unit firings was studied in six human muscles performing isometric constant-force contractions at 30% of the maximal level. The myoelectric signal was detected with a quadrifilar needle electrode and was decomposed into its constituent motor-unit action-potential trains with the Precision Decomposition technique, whose accuracy has been proven previously. 2. Synchronization was considered as the tendency of two motor units to fire at fixed time intervals with respect to each other more often than would be expected if the motor units fired independently. A rigorous statistical technique was used to measure the presence of peaks in the cross-interval histogram of pairs of motor-unit action-potential trains. The location of the center of peak as well as their width and amplitude were measured. A synch index was developed to measure the percentage of firings that were synchronized. The percentage of concurrently active motor-unit pairs that contained synchronized firings was measured. 3. Synchronization of motor-unit firings was observed to occur in two modalities. The short-term modality was seen as a peak in the cross-interval histogram centered about zero-time delay (0.5 +/- 2.9 ms, mean +/- SD) and with an average width of 4.5 +/- 2.5 ms. The long-term modality was seen as a peak centered at latencies ranging from 8 to 76 ms. On the average, the peaks of the long-term synchronization were 36% lower but had approximately the same width as the peaks for the short-term synchronization. Short-term synchronization was seen in 60% of the motor-unit paris, whereas long-term synchronization was seen in 10% of the pairs. 4. Short-term synchronization occurred in bursts of consecutive firings, ranging in number from 1 to 10, with 91% of all synchronized firing occurring in groups of 1 or 2; and the bursts of discharges appeared at sporadic times during the contraction. 5. The amount of synchronization in motor-unit pairs was found to be low. In the six muscles that were tested, an average of 8.0% of all the firings were short-term synchronized, and an average of 1.0% were long-term synchronized. The synch index was statistically indistinguishable (P = 0.07-0.89) among the different muscles and among 9 of the 11 subjects tested. 6. Sixty percent of concurrently active motor-unit pairs displayed short-term synchronization, 10% of the pairs displayed long-term synchronization, and 8% displayed both modalities.(ABSTRACT TRUNCATED AT 400 WORDS)
Total sleep deprivation in the rat transiently abolishes the delta amplitude response to darkness: implications for the mechanism of the “negative delta rebound”
Authors: Feinberg I. , Campbell I. G.
Published: December 2017

1. The homeostatic model of delta sleep has provided a useful framework for basic sleep research. This model is based on the relation of delta EEG to the duration of prior waking in man, a relation highlighted by the marked increase (rebound) in the delta EEG of nonrapid eye movement (NREM) sleep that follows total sleep deprivation (TSD). The generality of this model is severely challenged by the response to TSD in the rat. In the 12-h light period (LP) that immediately follows TSD, the rat shows a massive increase in REM sleep but only a modest increase in NREM delta EEG. Although this initial delta increase does not nearly compensate for the delta lost during deprivation, the rat then exhibits a depressed rate of delta production (the “negative delta rebound”). This robust and reproducible reaction worsens the delta deficit. 2. Using rats with chronic electrode implantations, we deprived them of all sleep for 24 h by handling them gently when they became inactive. We found that the negative delta rebound entails a transient, near-total failure of delta amplitude to increase normally in response to the onset of darkness. This loss of the rat's EEG response to darkness suggests a disruption of basic sleep physiology and raises the possibility that the negative rebound is also a pathological response. 3. We hypothesize that the negative rebound is maladaptive, and is caused by the massive increase in REM sleep that precedes it; this hypothesis can be tested experimentally.(ABSTRACT TRUNCATED AT 250 WORDS)
An active membrane model of the cerebellar Purkinje cell. I. Simulation of current clamps in slice
Authors: De Schutter E. , Bower J. M.
Published: December 2017

1. A detailed compartmental model of a cerebellar Purkinje cell with active dendritic membrane was constructed. The model was based on anatomic reconstructions of single Purkinje cells and included 10 different types of voltage-dependent channels described by Hodgkin-Huxley equations, derived from Purkinje cell-specific voltage-clamp data where available. These channels included a fast and persistent Na+ channel, three voltage-dependent K+ channels, T-type and P-type Ca2+ channels, and two types of Ca(2+)-activated K+ channels. 2. The ionic channels were distributed differentially over three zones of the model, with Na+ channels in the soma, fast K+ channels in the soma and main dendrite, and Ca2+ channels and Ca(2+)-activated K+ channels in the entire dendrite. Channel densities in the model were varied until it could reproduce Purkinje cell responses to current injections in the soma or dendrite, as observed in slice recordings. 3. As in real Purkinje cells, the model generated two types of spiking behavior. In response to small current injections the model fired exclusively fast somatic spikes. These somatic spikes were caused by Na+ channels and repolarized by the delayed rectifier. When higher-amplitude current injections were given, sodium spiking increased in frequency until the model generated large dendritic Ca2+ spikes. Analysis of membrane currents underlying this behavior showed that these Ca2+ spikes were caused by the P-type Ca2+ channel and repolarized by the BK-type Ca(2+)-activated K+ channel. As in pharmacological blocking experiments, removal of Na+ channels abolished the fast spikes and removal of Ca2+ channels removed Ca2+ spiking. 4. In addition to spiking behavior, the model also produced slow plateau potentials in both the dendrite and soma. These longer-duration potentials occurred in response to both short and prolonged current steps. Analysis of the model demonstrated that the plateau potentials in the soma were caused by the window current component of the fast Na+ current, which was much larger than the current through the persistent Na+ channels. Plateau potentials in the dendrite were carried by the same P-type Ca2+ channel that was also responsible for Ca2+ spike generation. The P channel could participate in both model functions because of the low-threshold K2-type Ca(2+)-activated K+ channel, which dynamically changed the threshold for dendritic spike generation through a negative feedback loop with the activation kinetics of the P-type Ca2+ channel. 5. These model responses were robust to changes in the densities of all of the ionic channels.(ABSTRACT TRUNCATED AT 400 WORDS)
Inositol 1,4,5-trisphosphate-gated conductance in isolated rat olfactory neurons
Authors: Okada Y. , Teeter J. H. , Restrepo D.
Published: December 2017

1. The effect of intracellular application of inositol 1,4,5-trisphosphate (IP3) from the patch pipette was analyzed in isolated rat olfactory neurons under whole-cell patch clamp. 2. Intracellular dialysis of 10 microM 1,4,5-IP3 in K(+)-internal solution induced a sustained depolarization of 35.8 +/- 10.5 (SD) mV (n = 16). The IP3-induced response was observed in 75% of the cells dialyzed with IP3 but not when 10 microM ruthenium red was also included in the pipette solution (4 cells). Lower concentrations (50-100 nM) of 2,4,5-IP3 induced similar responses to those produced by 1,4,5-IP3 in five of eight olfactory neurons. 3. Steady-state I-V relationships of IP3-gated currents with K(+)-internal solution were classified into two types: outwardly rectifying and N-shaped. In Cs(+)-internal solution outwardly rectifying and linear patterns were observed. 4. The IP3-induced currents were inhibited by external Cd2+ (1 mM). The reversal potentials of the Cd(2+)-inhibitable currents were -16.1 mV (n = 2) and -29.0 +/- 7.1 mV (n = 3) for the outwardly rectifying and N-shaped types, respectively, in K(+)-internal solution. The reversal potential was -5.9 +/- 6.8 mV (n = 5) in the Cs(+)-internal solution. 6. In contrast, the Ca(2+)-ionophore, ionomycin (5 microM) hyperpolarized the olfactory neurons and greatly potentiated the outward currents at positive holding membrane potential. 7. The data suggest that IP3 can depolarize rat olfactory neurons without mediation by intracellular Ca2+.