bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of primate joint afferent neurons to mechanical stimulation of knee joint
Authors: Grigg P. , Greenspan B. J.
Published: December 2017

1. One hundred thirty-eight knee joint afferents from posterior articular nerve (PAN), in primates, were recorded in dorsal root filaments. Responses of afferents were studied in relation to both passive manipulations of the knee and active contractions of quadriceps, semimembranosus, and gastrocnemius muscles. 2. When the knee was passively rotated, most neurons discharged only when extreme angular displacements were achieved. Response of neurons responding to passive extensions was linearly related to the torque applied to the knee. With maintained extensions, discharge in extension neurons adapted slowly. Some of the time constants of adaptation were similar to those for simultaneously recorded torque relaxation. 3. Contractions of quadriceps, semimembranosus, or gastrocnemius muscles could activate many neurons in the absence of changes in joint angle. For quadriceps-activated neurons, rather high torques (mean = 2,450 g with cm) were required. 4. The results support the hypothesis that joint afferents function as capsullar stretch receptors, responding to those mechanical events which result in loading of the capsule.
Simple striate neurons in the cat. II. Mechanisms underlying directional asymmetry and directional selectivity
Authors: Emerson R. C. , Gerstein G. L.
Published: December 2017

1. Directionally asymmetric (DA) units respond preferentially to one direction of image movement. If that preferred direction is independent of stimulus contrast then the DA unit is considered directionally selective (DS). We have analyzed receptive-field (RF) properties of striate units with these properties by presenting bar-shaped stimuli that are moved in a stepwise sequence. Short interstimulus durations for certain ranges of step size elicit DA responses similar to those from smooth movement, while still allowing identification of on- and off-components of the response. 2. We have been able to isolate three mechanisms underlying DA and DS. The simplest, superposition, explains the dependence of preferred direction on stimulus contrast found in some DA units. It relies completely on asymmetries in static RF regions to provide an advantage for one direction of image motion by means of the simultaneity of image elements leaving an apparently inhibitory region and entering an excitatory one. 3. For all DA and DS units we have encountered forward inhibition of otherwise excitatory influences that reduces the responsiveness in the antipreferred direction. The spatial specificity of inhibitory target RF regions and the nonlinearity of the effect suggest that lateral inhibition may be transmitted via sequence-detecting subunits. 4. Units that do not show superposition in the preferred direction exhibit forward facilitation of responses in a nonlinear and target-specific way which suggests that facilitation may also be transmitted via sequence-detecting subunits. 5. Each of these mechanisms depends on short-lived influences that are laterally transmitted between 0.125 and 0.5 degrees in visual space. These spatial and temporal values are appropriate for the analysis of smooth movement by the visual system. 6. Stepwise movement sequences using dark bars on a bright background demonstrate for some DA units exactly the same mechanisms as demonstrated using bright-bar sequences in other units or, in the case of DS units, in the same units. In such DS units, which do not normally exhibit strong stationary RF asymmetries, differential sensitivity of the nonlinear DS mechanisms to stimulus elements of either contrast will yield an effective preferred movement direction for complex stimuli.
Response characteristics of cutaneous cold receptors in the monkey
Authors: Kenshalo D. R. , Duclaux R.
Published: December 2017

1. The receptive fields of 48 specific cold units, located in the hairy and glaborous skin of fore- and hindlimbs of rhesus monkeys, were mapped and scale drawings made. Forty-five percent had single spotlike receptive fields of 1-2 mm diameter or were up to 2 mm wide and 3-5 mm long, and formed straight, crescent, or right-angle shapes. The remaining 55% had two to five discrete spots or small areas innervated by a single fiber. Area or number of receptive fields per unit did not vary significantly along the limb axis. 2. Of the 48 specific cold units, 15 were held sufficiently long to record their dynamic responses to intensity-rate series of temperature changes from several adapting temperatures (ATs) between 20 and 45 degrees C. Six cold units showed a paradoxical increase in the steady-state response at the 45 degrees C compared to that at the 40 degrees C AT. Of the 15 cold units, 7 discharged in bursts at the 35 degrees C or lower ATs. The proportion of short intervals (intraburst intervals) increased as the adapting temperature decreased. 3. Both the latency and the temperature change at the onset of the dynamic response to cooling remained relatively constant for ATs up to and including 35 degrees C. The response latencies were approximately 200-400 ms, while the temperature changes at response onset were -0.02 to -0.06 degrees C. Both increased sharply at the 40 degrees C and still more at the 45 degrees C ATs. 4. The rate of increase in the frequency of the dynamic response to cooling by the fast rate increased to maximum at the 30 degrees C AT and then decreased at the higher ATs. For the slow rate the highest rate of increase in frequency occurred at the 20 degrees C AT. The fast rate of cooling always induced a faster rate of increase in frequency than slow rate of cooling. 5. Four indices of response magnitude were used in the analysis of the dynamic responses. These were peak frequency, cumulative impulses in the first 4 s following stimulus onset, average frequency during stimulations plus 3 s, and the total impulses during stimulation. The first three indices gave similar representations of the dynamic responses to the rate and intensity of cooling and the effect of the AT. The slow rate of cooling invariably yielded a smaller index of response magnitude than the fast rate. The difference became more pronounced as the intensity of cooling increased. The stimulus intensity-response magnitude functions were nonlinear. This nonlinearity was more pronounced at the low than at the high ATs. As the AT was increased, the response indices approached linearity at the 35 and 40 degrees C ATs. The greatest sensitivity of cold units to cooling was from the 35 degrees C AT. The fourth index, total impulses during stimulation minus steady state, gave a different picture. This index of response magnitude was linearly related to stimulus intensity for both rates of cooling from all adapting temperatures except for the slow rate of cooling from the 45 degrees C AT...
Reflex control of locomotion as revealed by stimulation of cutaneous afferents in spontaneously walking premammillary cats
Authors: Duysens J.
Published: December 2017

1. Stimulation of different hindlimb nerves in spontaneously walking premammillary cats was used in order to examine the effects of sensory input on the rhythmic motor output. 2. Stimulation of the tibial or sural nerve at low intensities caused the burst of activity in the triceps surae or semimembranosus to be prolonged if stimuli were given during the extension phase. When applied during the flexion phase, the same stimuli shortened the burst of activity in the pretibial flexors and induced an early onset of the extensor activity, except if stimuli were given at the very beginning of the flexion phase, when flexor burst prolongations or rebounds were observed instead. 3. These effects were related to activation of large cutaneous afferents in these nerves since the results could be duplicated by low-intensity stimulation of the tibial nerve at the ankle or by direct stimulation of the pad. 4. In contrast, activation of smaller afferents by high-intensity stimulation resulted prolongations of the flexor burst and/or shortenings of the extensor burst for stimuli applied before or during these bursts, respectively. 5. It was concluded that the large and small cutaneous afferents make, respectively, inhibitory and excitatory connections with the central structure involved in the generation of flexion during walking.
Responses of single cells in cat visual cortex to prolonged stimulus movement: neural correlates of visual aftereffects
Authors: Vautin R. G. , Berkley M. A.
Published: December 2017

1. The activity of single cortical cells in area 17 of anesthetized and unanesthetized cats was recorded in response to prolonged stimulation with moving stimuli. 2. Under the appropriate conditions, all cells observed showed a progressive response decrement during the stimulation period, regardless of cell classification, i.e., simple, complex, or hypercomplex. 3. The observed response decrement was shown to be largely cortical in origin and could be adequately described with an exponential function of the form R = Rf +(R1-Rf)e-t/T. Time constants derived from such calculations yielded values ranging from 1.92 to 12.45 s under conditions of optimal-stimulation. 4. Most cells showed poststimulation effects, usually a brief period of reduced responsiveness that recovered exponentially. Recovery was essentially complete in about 5-35 s. 5. The degree to which stimuli were effective at inducing response was shown to have significant effects on the magnitude of the response decrement. 6. Several cells showed neural patterns of response and recovery that suggested the operation of intracortical inhibitory mechanisms. 7. A simple two-process model that adequately describes the behavior of all the studied cells is presented. 8. Because the properties of the cells studied correlate well with human psychophysical measures of contour and movement adaptation and recovery, a causal relationship to similar neural mechanisms in humans is suggested.
Mouse spinal cord in cell culture. I. Morphology and intrinsic neuronal electrophysiologic properties
Authors: Ransom B. R. , Neale E. , Henkart M. , Bullock P. N. , Nelson P. G.
Published: December 2017

1. Reliable methods for establishing fetal mouse spinal cord (SC) and dorsal root ganglion (DRG) cells in long term (greater than 1 mo) dissociated cell cultures are described. These cells have been studied by morphologic and intracellular electrophysiologic techniques. 2. Cells studied electrophysiologically can be relocated after preparation for electron microscopy and examined in thin sections. The electron microscope shows that the surface membranes of these cells were directly accessible to the culture medium. The surfaces of SC cells were studded with synaptic boutons, whereas the DRG cell surfaces generally had none. 3. Current-voltage relationships and linear electrotonic properties of the neurons are described. Delayed and anomalous rectification were seen in both cell types. The length of SC cell dendrites was about one characteristic electrotonic length, while little or no contribution of the relatively sparse DRG cell processes was seen in the transient responses of the DRG cells. 4. Postspike and posttetanic hyperpolarizations in DRG cells were due to a surface membrane conductance increase; this was probably primarily an increase in K+ conductance. Post-activation hyperpolarization in SC cells was primarily due to activation of an electrogenic Na+ pump.
Optical recording of neuronal activity in an invertebrate central nervous system: simultaneous monitoring of several neurons
Authors: Salzberg B. M. , Grinvald A. , Cohen L. B. , Davila H. V. , Ross W. N.
Published: December 2017

1. Using an optical method for measuring membrane potential, we have been able to monitor action-potential activity simultaneously in 14 neurons of the supraesophageal ganglion of the barnacle. 2. Under favorable conditions, 4-mV synaptic potentials could also be detected optically.
Discrimination of orientation and position disparities by binocularly activated neurons in cat striate cortex
Authors: Nelson J. I. , Kato H. , Bishop P. O.
Published: December 2017

Page 275: J. I. Nelson, H. Kato, and P. O. Bishop, “Discrimination of orientation and position disparities by binocularly activated neurons in cat striate cortex.” The legend to the figure at the bottom of page 325 should read: fig 9. Matrix stimulation experiment for a complex cell. The 17 position disparity tuning curves, separated from each other by orientation disparity increments of 7°, span an orientation range of 112°. Each position disparity tuning curve has six increments of 24' arc disparity spanning 2.4°. The stimulus orientation disparities were obtained by keeping the stimulus orientation for the left eye fixed at 112° and varying the orientation for the right eye. Monocular controls (open circles, filled triangles, and short continuous lines) same as for Fig. 8.
Properties of auditory nerve responses in absence of outer hair cells
Authors: Dallos P. , Harris D.
Published: December 2017

1. Recordings were made from chinchilla auditory nerve fibers after portions of the cochlear outer hair cell (OHC) population were destroyed with the antibiotic kanamycin. In most cases the inner hair cell (IHC) population was completely preserved as determined by phase-contrast microscopy. We presume that the remaining IHCs are functionally normal, and thus that recordings obtained from fibers originating from the lesioned cochlear segment reflect IHC behavior. 2. Behavioral thresholds were measured for all animals both before and after the production of the cochlear lesion. The audiograms and the histological evaluation of the ears were the basis for assessing whether a particular fiber originated in a normal, pathological (shifted threshold; IHC only), or border region. These criteria also identified the animals that sustained IHC damage together with the destruction of part of the OHC population. Only the data obtained from those fibers which probably originated from the OHC-free segment of the cochlea are considered in detail. 3. Fibers whose characteristic frequency (CF) identified them as belonging to the normal (audiometrically and histologically) region, were found to be normal in all respects. 4. Fibers from the border region (where the audiogram has a steep slope between normal and hearing-loss regions probably corresponding to the segment where OHC loss progresses from less than 10% to more than 90%) had very complex response patterns. Their frequency threshold curves (FTC) showed great variability. In general, the closer the fiber was to the fully developed lesion, the more abnormal its FTC became. 5. Those units that were concluded to have originated from the OHC-free part of the cochlea could be divided into three categories on the basis of the shape of their FTCs. A small fraction had very broad tuning (9%). The majority (53%) had approximately normal tail segment, normal bandwidth of the tip segment, and highly elevated threshold at CF. A group of fibers (38%) could not be assigned a CF. Probably the FTC of most of these latter fibers are similar to those of the previous group, but the sharply tuned short tip segment was either missed or was not reachable on account of its extremely high threshold level. 6. Such indexes of fiber response as latency, spontaneous rate, and time pattern (PST histograms) were not affected by the loss of OHCs. 7. On the basis of the data and of the assumptions made it was suggested that outer hair cells provide a frequency-dependent sensitizing influence to the inner hair cells. The frequency dependence could best be expressed as a flat-topped band pass characteristic.
Intracellular staining reveals different levels of stratification for on- and off-center ganglion cells in cat retina
Authors: Nelson R. , Famiglietti E. V. , Kolb H.
Published: December 2017

1. Ganglion cells in the retina of the cat were stained by intracellular dye injection after recording their responses to photic stimulation. 2. All cells encountered were divided into those giving on-responses and those producing off-responses, and the level of dendritic branching of these two groups was compared. Cells giving off-responses were found to branch high in the inner plexiform layer (IPL), near the amacrine cell bodies (sublamina a); those giving on-responses were found to branch lower in the inner plexiform layer (sublamina b). 3. Dye-injected cells varied widely in morphology and size, having cell bodies ranging in diameter from 8 to 32 micrometer and dendritic fields ranging from 25 to 490 micrometer in diameter; yet the sign of the response of each unit correlated only with the level of dendritic branching. Thus, no other morphological feature except stratification appears to be important in determining the sign of the response of these cells. 4. The stratification of ganglion cells into on- and off-layers parallels the distribution of the axon terminals of the flat and invaginating cone bipolars. Flat cone bipolars are in a position to contact off-center ganglion cells (in sublamina a) and invaginating cone bipolars are in a position to contact on-center ganglion cells (in sublamina b). 5. The rod and cone inputs to some cells were characterized by comparing their responses to deep red and blue rod-matched stimuli over a 2-log unit range starting at dark-adapted threshold. About half the cells appeared to be rod dominated under these conditions, whereas the others appeared to have mixed rod and cone signals. 6. The nature of the rod and cone pathways to ganglion cells is discussed.
Electrotonic properties of neurons: steady-state compartmental model
Authors: Perkel D. H. , Mulloney B.
Published: December 2017

1. If a neuron is represented by a network of resistively coupled isopotential regions, the passive flow of current in its dendritic structure and soma is described by a matrix differential equation. The matrix elements are defined in terms of membrane resistances and capacitances and of coupling resistances between adjoining regions. 2. A uniform cylidrical dendrite can be represented by a chain of identical regions. In this case, a closed-form mathematical expression is derived for the voltage attenuation factor of the dendrite at steady state in terms of the ratio of membrane resistance to coupling resistance. A numerical method is given to determine the coupling resistances, which in turn yield a specified attenuation factor. Related expressions are given for a dendrite coupled to a soma. Formulas are also derived for the input resistance in these configurations. 3. For more complicated neuronal structures, matrix manipulations are described which yield values for input resistances in all regions, attenuation factors between all pairs of regions, and values of applied voltages necessary to attain specified steady-state potentials. 4. Dynamic solutions to the differential equation provide voltage transients (PSPs). Comparison of the shape paramenters of these transients with those of experimental or cable-theoretical PSPs establishes the number of regions necessary to achieve a given degree of approximation to the transients predicted by cable theory.
Neuronal transmission through hippocampal pathways dependent on behavior
Authors: Winson J. , Abzug C.
Published: December 2017

1. In chronically prepared, freely moving rats, electrical stimulation was applied to the angular bundle, and responses were recorded extracellularly at a variety of sites in the ipsilateral hippocampal formation. At each recording site the stimulus-response relationship was tested during four different behavioral states. These were slow-wave sleep (SWS), REM sleep ( REM), and also two waking behaviors consisting of the still, alert condition (labeled SAL), and voluntary movement (AW theta). 2. Two varieties of evoked responses were recorded: those due to the synchronous firing of neuronal action potentials (EAPs) and those produced by excitatory synaptic activity (ESPs). The overall pattern of monosynaptic, di-, and trisynaptic responses found was similar in the rat to that found by Andersen et al. (3-5) in cat and rabbit. 3. When the trisynaptic EAP was recorded in CA1, the threshold was similar during all four behavioral states. However, suprathreshold stimuli evoked a greater response during SWS than during the other three states. The trisynaptic ESP was also greater during SWS. 4. Disynaptically, EAPs were recorded in CA3. These were greater in magnitude during SWS than during SAL, but were intermediate in mean amplitude during AWtheta and REM. Response variability was much greater during AWtheta and REM. 5. The monosynaptic EAP recorded in the upper blade of the dentate gyrus (DG) exhibited the same behaviorally correlated properties found disynaptically in CA3. 6. The monosynaptic ESP recorded in the DG, in contrast to the EAP, was greater in magnitude during SAL than during SWS. 7. The primary afferent volley was also recorded at high gain in the DG. The amplitude of this was found to be dependent solely on stimulus intensity and not on behavioral state. 8. The results are interpreted as suggesting that the granule cell membranes in the DG are relatively hyperpolarized during SAL compared with SWS as the result of either tonic excitatory bombardment occurring during SWS or tonic inhibitory bombardment during SAL.
Functional specificity of lateral geniculate nucleus laminae of the rhesus monkey
Authors: Schiller P. H. , Malpeli J. G.
Published: December 2017

1. This study investigated the functional specificity of the lateral geniculate mucleus (LGN) of the rhesus monkey using microelectrode-recording techniques. 2. The parvocellular laminae of the LGN receive input predominantly from medium-conduction-velocity optic tract fibers, while the magnocellular laminae receive fast-conducting axons from the retina. 3. Cells projecting from the parvocellular layers to area 17 have medium-conduction velocities, while those from the magnocellular layers are fast conducting. 4. The majority of cells in the parvocellular layers have a concentric color-opponent receptive-field organization. The receptive fields of magnocellular layers cells are also concentrically organized, but their center-surround organization is independent of wavelength. 5. Responses in the parvocellular layers are more sustained than in the magnocellular layers. 6. Cells in the dorsal pair of parvocellular layers are predominantly on-center. In the ventral pair of parvocellular layers, most cells are off-center. 7. Blue-selective cells are found predominantly in the ventral pair of parvocellular layers. All of these found gave on-responses to blue stimuli.
Receptive-field properties of neurons in different laminae of visual cortex of the cat
Authors: Leventhal A. G. , Hirsch H. V.
Published: December 2017

1. Receptive-field properties of neurons in the different layers of the visual cortex of normal adult cats were analyzed quantitatively. Neurons were classified into one of two groups: 1) S-cells, which have discrete on- and/or off-regions in their receptive fields and possess inhibitory side bands; 2) C-cells, which do not have discrete on- and off-regions in their receptive fields but display an on-off response to flashing stimuli. Neurons of this type rarely display side-band inhibition. 2. As a group, S-cells display lower relative degrees of binocularity and are more selective for stimulus orientation than C-cells. In addition, within a given lamina the S-cells have smaller receptive fields, lower cutoff velocities, lower peak responses to visual stimulation, and lower spontaneous activity than do the C-cells. 3. S-cells in all layers of the cortex display similar orientation sensitivities, mean spontaneous discharge rates, peak response to visual stimulation, and degrees of binocularity. 4. Many of the receptive-field properties of cortical cells vary with laminar location. Receptive-field sizes and cutoff velocities of S-cells and of C-cells are greater in layers V and VI than in layers II-IV. For S-cells, preferred velocities are also greater in layers V and VI than in layers II-IV. Furthermore, C-cells in layers V and VI display high mean spontaneous discharge rates, weak orientation preferences, high relative degrees of binocularity, and higher peak responses to visual stimulation when compared to C-cells in layers II and III. 5. The receptive-field properties of cells in layers V-VI of the striate cortex suggest that most neurons that have their somata in these laminae receive afferents from LGNd Y-cells. Hence, our results suggest that afferents from LGNd Y-cells may play a major part in the cortical control of subcortical visual functions.
Center and surround mechanisms of opponent-color X and Y ganglion cells of retina of macaques
Authors: de Monasterio F. M.
Published: December 2017

1. Opponent-color ganglion cells of macaques can be classed as X or Y. Cells with a cone-specific receptive-field organization (center and surround receiving input from spectrally different cone types) have a linear summation, whereas cells with a cone-mixed organization (center and surround partly mediated by input from the same cone type) have a nonlinear summation. 2. Pure center and pure surround responses of Y-cells have a fast decay and show conspicuous transients at stimulus offset and onset; pure responses of X-cells have a slow decay and show fewer transients, especially at stimulus offset. 3. Sensitivity profiles based on pure responses elicited in conditions of chromatic adaptation of the opponent responses show that Y-cells have unimodal center and unimodal surround profiles, whereas X-cells have unimodal center and bimodal surround profiles. 4. Responses receiving contribution from both opponent mechanisms (mixed) have different time course and pattern in X- and Y-cells. Mixed response of Y-cells show a discontinuity in cell firing during the transient (on) component of cell activity, which has a higher sensitivity than other waveform changes produced by concurrent stimulation of the opponent mechanism. This discontinuity occurs with stimulus conditions that also elicit proximal negative responses in the local electroretinogram and appears to be due to a centrally located process having some degree of rectification.
Signs of functional maturation of peripheral auditory system in discharge patterns of neurons in anteroventral cochlear nucleus of kitten
Authors: Brugge J. F. , Javel E. , Kitzes L. M.
Published: December 2017

1. Responses to pure tones were recorded from single neurons in the anteroventral cochlear nucleus (AVCN) in kittens ranging in age from 4 to 45 days. Different response properties mature at different times after birth. 2. The shapes of response areas of AVCN neurons after the 1st postnatal week resemble those recorded in the AVCN and auditory nerve of the adult. During the 1st wk after birth the high-frequency portion of the response area is extended. Phase-locked responses to stimulus frequencies below about 600 Hz occur at this time. Phase vs. frequency measurements and shapes of response areas indicate that by the end of the 1st postnatal week the cochlear partition may be capable of supporting a traveling wave along most of its length. 3. Functional development proceeds through a second phase which lasts until the end of the 2nd or the beginning of the 3rd wk of life. During that time threshold, maximal discharge rate, and average first-spike latency achieve adult values. 4. Phase-locking to low-frequency tones, to the extent displayed by phase-sensitive neurons in the adult AVCN or auditory nerve, is achieved last, after the 3rd or 4th wk postpartum.
Nociceptive responses of neurons in medial thalamus and their relationship to spinothalamic pathways
Authors: Dong W. K. , Ryu H. , Wagman I. H.
Published: December 2017

1. An extracellular study of the cat medial thalamus has revealed four types of somatosensory neurons. These were located primarily in the n. parafascicularis, n. subparafascicularis, and n. centralis lateralis; none were found in the n. centrum medianum. There was no functional segregation of neurons within each nucleus or between nuclei. Each type of neuron had large and often bilateral receptive areas. No somatotopic organization of neurons was found within the medial thalamus. 2. Noxious (N) and noxious-tap (NT) neurons comprising 72% of the sample (78 of 109 total) were considered to be nociceptive. N cells responded exclusively to noxious mechanical stimulation of skin, muscle fascia, tendons, and joints, and to direct stimulation of A-delta- and C-fiber groups in cutaneous, articular, and muscle nerves. NT cells responded to noxious and tap stimulation in a differential manner and to stimulation of the entire spectrum of A- and C-fibers. N and NT cells accurately signaled the duration of noxious mechanical stimulation. Their nociceptive responses were also graded as a function of both noxious stimulus intensity and the number of activated A-delta- and C-fibers. Stimulation of A- and C-fibers evoked, respectively, an inital burst and a late burst of discharges. A brief period of inhibition intervened between the initial and late bursts of NT cells. Prolonged afterdischarge was often observed following noxious natural stimulation or stimulation of A-delta- and C-fibers. The phenomenon of discharge "windup" was observed during iterative stimulation of C-fibers. 3. Tap (T) neurons (10%) responded only to brisk but innocuous taps applied to skin or underlying tissue. These cells were driven only by activation of A-alpha- and A-beta-fibers. The response to such stimulation was seen as an initial burst of discharges followed by an inhibitory period. 4. Inhibited (I) neurons (18%) had resting discharges that were inhibited by noxious stimuli and stimulation of A-beta- and C-fiber groups. 5. The results obtained from monitoring the peripherally evoked responses of nociceptive N and NT neurons before and after selective lesions of the spinal cord strongly suggested that the spinothalamic tracts were the only spinal projections mediating A- and C-fiber input to these cells. Each spinothalamic tract apparently carried information originating from both sides of the body.
Interlimb coordination during stepping in the cat: an electromyographic analysis
Authors: English A. W.
Published: December 2017

1. Simultaneous electromyographic (EMG) records were obtained from a single-joint extensor muscle of each of the four limbs of intact cats during repeated overground stepping trials. 2. In each limb, the temporal spacing of step cycles was determined by measurements of the intervals between consecutive terminations of EMG activity, since this occurs in a consistent relationship to the removal of the limb from the ground. By measuring the latencies between step cycles so determined, the temporal spacing of step cycles between limbs was determined. Each latency was expressed as a function of step duration or as a phase interval. 3. Analysis of the cooordination of step cycles of both homologous limb pairs (the forelimbs and hindlimbs), both homolateral limb pairs (the fore- and hindlimb on the right and left sides), and both sets of diagonal limbs suggest that the step cycles of the four limbs are coordinated according to a few frequently occurring patterns. However, the representation of a large number of phase intervals between these preferred patterns indicates a substantial amount of variability in interlimb coupling. 4. Analysis of the interaction of different interlimb-coupling patterns indicates that during alternate coordination of hindlimbs, coupling of the other limbs is fairly predictable. The step cycles of the forelimbs and hindlimbs are spaced according to a trotting form of coupling. During in-phase coordination of hindlimbs, the patterns of coordination of the other limbs are more diffuse. Forelimbs step cycles are coupled via a number of different modes, as are those of the forelimbs and hindlimbs. 5. It is concluded that the step cycles of different limbs are coordinated, but the association of observed patterns of coordination with any known neural pathways or the interaction of neural pathways should be approached with caution. The variability about the frequently occurring patterns is interpreted as an expression of the faculatative capabilities of the neural mechanisms controlling locomotion. Thus, these data favor a model of interlimb control during stepping, which recognizes preferred patterns of coordination and the variability about these patterns.
Physiological properties of muscle spindles in dorsal neck muscles of the cat
Authors: Richmond F. J. , Abrahams V. C.
Published: December 2017

1. Single-fiber recording was used to examine the properties of 107 spindle endings in cat biventer cervicis (BC) and complexus (CM) muscles. Responses of receptors were examined following muscle contraction and ramp and hold stretch. Twenty-two endings in splenius (SP) were also examined, but their responses could not be quantitated because the anatomy of SP prevented the application of appropriate stretches. 2. Conduction velocitites of spindle afferents ranged from 13 to 90 m/s. Endings with primary response patterns usually had faster conduction velocities than secondary endings, but there was overlap in the conduction velocity ranges of the two subgroups. 3. Most neck spindle afferents could be classified as either primary or secondary by a constellation of physiological criteria including dynamic response pattern, dynamic index, and variability of resting discharge frequency. However, 22 of 107 endings from BC and CM had responses with characteristics intermediate between primary and secondary responses. The possible sources of these characteristics are discussed. 4. Despite the similarity in properties between spindles of different neck muscles, the length sensitivities of CM spindles were high compared to those of BC spindles. CM spindles showed length-related modulation of firing frequency over a more restricted range of initial muscle lengths than did BC spindles. 5. Eight Golgi tendon organs (GTO) were identified by their characteristics responses. Conduction velocities obtained for five GTO afferent nerves ranged from 50 to 67 m/s. Recordings were also made from receptros in deep muscles surrounding the vertebrae. These receptors had properties characteristic of muscle spindles.
Slowly adapting receptors in cat hip joint
Authors: Carli G. , Farabollini F. , Fontani G. , Meucci M.
Published: December 2017

1. The activity of slowly adapting joint receptors was recorded from fibers of the posterior articular nerve of the hip in deeply anesthetized cats. The static stimulus was any position of the femur maintained at least 2 min after passive displacement. Most of the fibers are active in all the positions where the femur may be placed. Modulation in the discharge frequency occurs in any axis of displacement, and higher activity is recorded at extreme positions. The maximal discharge may be reached in several positions of the femur far away from one another. 2. Adaptation to static stimuli occurs in all the receptors. Joint receptors fire at very regular, steady rates; the mean coefficient of variation was 0.079. 3. In most of the receptors, when the femur is displaced along a single axis, the frequency of discharge varies as a monotonic function of joint position. This relationship could be described either by linear and logarithmic or by linear and power functions, according to the criteria adopted to indicate the intensity of the stimulus. 4. Repetition of identical static stimuli results in different responses. 5. The static properties of the receptors are not modified by the section of periarticular muscles. 6. Hip joint receptors are able to code hip joint position.
Composition of geniculostriate input ot superior colliculus of the rhesus monkey
Authors: Schiller P. H. , Malpeli J. G. , Schein S. J.
Published: December 2017

1. In order to examine the composition of the geniculostriate input to the superior colliculus, microelectrode recordings were undertaken in this structure of the rhesus monkey while parvocellular or magnocellular laminae of the LGN were reversibly inactivated by injecting minute quantities of lidocaine or MgCl2. 2. The inactivation of magnocellular laminae disrupted the visually driven activity of most cells in the topographically corresponding areas of the colliculus, but not in the superficial retinotectal recipient zone. The inactivation of parvocellular lamina had no effect on the visually driven activity of collicular cells. 3. Several controls were carried out to rule out the possibility of intervention with fibers of passage. We ascertained that the LGN injections did not affect the direct retinotectal pathway by comparing the effect of such inactivation with the effect produced by reversibly cooling visual cortex. These two manipulations yielded similar results: cells in the most superficial regions of the superior colliculus were unaffected by both cortical cooling and by magnocellular injections, while below this region the response of collicular cells was reduced or eliminated in both cases. 4. These results suggest that the indirect visual pathway to the superior colliculus via cortex is activated selectively by the broad-band system, which is relayed through magnocellular LGN. The color-opponent system does not appear to have a corticotectal input sufficient to drive collicular cells independently.
Spontaneous electrical activity and interaction of large and small cells in cardiac ganglion of the crab, Portunus sanguinolentus
Authors: Tazaki K. , Cooke I. M.
Published: December 2017

1. Semi-isolated preparations of the nine-celled cardiac ganglion of the crab, Portunus sanguinolentus, were studied electrophysiologically, using simultaneous recording from extracellular and two or three intracellular electrodes. Nine penetrations of small cells were achieved. 2. Three large (80 x 120 micron) cells lie near the anterior end of the 5-mm main trunk; two large and four small (less than 50 micron) cells at the posterior end. Large-cell axons pass along the main trunk and then exit to innervate cardiac muscle; small-cell axons do not leave the ganglion. 3. The semi-isolated ganglion produces spontaneous electrical activity organized into regularly patterned, rhythmic bursts of large- and small-cell impulses recurring at rates of 0.3-0.6/s and lasting 500-800 ms. Small impulse activity commences and ends each burst. Small cells fire trains during the burst, but impulses are not synchronized among them. Large-cell trains are synchronous, are at about one-half the frequency, and have fewer impulses than small-cell trains. 4. Intracellular recordings from small cells show a slow, pacemaker depolarization from a maximum membrane potential of -54 mV leading with only a slight inflection at ca. -50 mV to a depolarized plateau at ca. -40 mV; nonovershooting impulses are superimposed on this but cease before it repolarizes. Impulses, therefore, arise at a site distant from the soma and do not invade it. Deflections suggesting synaptic potentials are not seen. 5. Intracellular recordings from large cells show complex depolarizations corresponding to extracellularly recorded bursts. These represent excitatory postsynaptic potentials (EPSPs) corresponding with individual small-cell impulses, attenuated, non-overshooting spikes, and an underlying slow depolarization; usually no pacemaker depolarization is apparent between bursts. Chemically mediated transmission is probable for the EPSPs because they show delay, increase in amplitude with hyperpolarization, sometimes show facilitation, and are reduced in saline having one-third Ca, 3 x Mg. 6. EPSPs, impulses, and the slow depolarization occur synchronously among the large cells. Potentials recorded from posterior cells are attenuated and slower than those of the anterior cells. This is interpreted to reflect sites of occurrence more distant from the soma in the posterior than in the anterior cells. Impulses do not invade the somata. 7. Intracellular recordings from large-cell axons 4 mm from the soma show overshooting action potentials arising sharply from a base line. EPSPs are absent or highly attenuated and there is little underlying depolarization (less than 2 mV). 8. Current passing with electrodes intracellular to two cells has established directly that all large cells are electrotonically coupled and that an anterior cell and a small cell are coupled. Changes of burst rate during current passing into any large cell indicate that all large cells and small cells are electrotonically coupled. 9...
Warm fibers innervating palmar and digital skin of the monkey: responses to thermal stimuli
Authors: Darian-Smith I. , Johnson K. O. , LaMotte C. , Shigenaga Y. , Kenins P. , Champness P.
Published: December 2017

1. Three hundred fourteen warm fibers innervating the glabrous skin of the monkey's hand were isolated by dissection in the median and ulnar nerves in two species, Macaca mulatta and M. nemestrina. Fiber samples in the two species were functionally similar and uniform in their properties. Their mean conduction velocity of 1.2 m/s (SD 0.5; n = 50) implies that these warm fibers were all unmyelinated. 2. A parametric study of the responses of warm fibers to near-rectangular warming and cooling pulses applied to glabrous skin was completed using 104 fibers. At a steady base-line skin temperature (T-base) of 34 degrees C all these warm fibers responded to warming pulses in the intensity range 0--8 degrees C with a simple, uniform discharge, which reached a peak rate of 1.5--4.0 s after the onset of stimulation; subsequent decay in this discharge rate had a time constant of 5--12 s and was virtually independent of the intensity of the warm pulse. The intensity function was linear for most fibers when the interstimulus interval was 60 s or longer. At a T-base of 29 degrees C, warm fibers were less responsive, but the temporal profile of the response was similar to that at a T-base of 34 degrees C in the intensity range 4--8 degrees C, and the intensity function was again linear. 3. At a T-base of 39 degrees C the intensity function of each warm fiber was complex. Most fibers responded briskly to warming pulses of 2--4 degrees C: the response to more intense warming pulses, particularly when the skin temperature rose above 45 degrees C, was structured and reproducible, but varied greatly among different fibers. With some the discharge evoked was of very high frequency for a few seconds, and then ceased. More than 80% of the sample of warm fibers did not discharge at all in response to warming pulses, which raised the skin temperature to 50 degrees C or above. 4. The responsiveness of warm fibers to warming pulses was dependent on previous stimulation when the interstimulus interval was less than 60 s. This temporal suppression was precisely structured and was examined quantitatively for trains of warming pulses, each lasting 4.0 s and presented every 10 s. The pattern of suppressive interaction was similar in form to that previously reported for cold fibers innervating palmar skin. 5. A quantitative study of the receptive fields of individual warm fibers demonstrated a spatiotemporal response pattern, which is best described in terms of a focal receptor zone less than 1 mm in diameter surrounded by thermally conducting skin. The skin's thermal conductivity is paramount in determining the warm-fiber's receptive-field characteristics. 6. The responses of warm fibers to cooling pulses and to warming ramps are described.
Reinnervation of glabrous skin in baboons: properties of cutaneous mechanoreceptors subsequent to nerve crush
Authors: Dykes R. W. , Terzis J. K.
Published: December 2017

1. A total of 791 fibers were isolated from the ulnar nerves of five baboons. Over half of these were obtained from the right ulnar nerves subsequent to reinnervation following a nerve crush; the other fibers were obtained from the undamaged left ulnar nerves. 2. The conduction velocities in the proximal portion of the injured axons dropped below normal, and this reduction persisted until reinnervation appeared nearly complete. 3. The response properties of 65 cutaneous afferent fibers serving reinnervated glabrous skin were compared to 80 fibers from normal skin. 4. Of the afferent fibers reinnervating skin, the proportion judged to have abnormal response properties was not significantly greater than the proportion in normal skin. 5. After reinnervation, cutaneous rapidly adpating fibers displayed tuning curves characteristic of their submodality, while some cutaneous slowly adapting fibers could still be differentiated into type I and type II fibers. However, both types of slowly adapting fibers displayed an increased rate of adaptation and a lowered sensitivity to sustained displacements even at 5 mo following reinnervation. 6. In conclusion, the cutaneous mechanoreceptors in reinnervated glabrous skin regained response properties that allowed them to be assigned to the same submodalities found in normal skin. Submodality was recognizable at an early stage when the receptive field was still immature and when the threshold was elevated. With time, the receptive-field sizes and shapes returned to normal, the thresholds approached normal, and the remaining differences from normal cutaneous afferent fibers became minor.
Different cortical areas in man in organization of voluntary movements in extrapersonal space
Authors: Roland P. E. , Skinhoj E. , Lassen N. A. , Larsen B.
Published: December 2017

1. This paper reports regional cerebral blood flow (rCBF) measurements in 254 cortical regions with 133Xe injected into the internal carotid artery in 19 patients, none of whom had any major neurological defect. The purpose was to demonstrate the pattern of cortical activity, as revealed by rCBF increases, during two types of unilateral voluntary movement in extrapersonal space: a) the maze test, series of fast isolated movements in various directions in a frame, executed under verbal command; and b) the drawing of a spiral in the air. 2. Both types of movements were associated with increases of rCBF in the supplementary motor area (bilaterally), the convexity part of the premotor area (bilaterally), the primary sensorimotor hand and arm area (contralaterally), and in the superior and inferior parietal region (bilaterally). 3. During the maze test there were, in addition, bilateral focal increases of the blood flow in the auditory areas, the inferior frontal regions, and the frontal eye fields. 4. It is concluded that the supplementary motor areas, which are also active during programming and execution of movement sequences in intrapersonal space (33), elaborate programs for motor subroutines necessary in skilled voluntary motion. The convexity parts of the premotor areas are activated when a new motor program is established or a previously learned motor program is modulated. The primary motor area is the exclusive executive locus for voluntary movements of the hand and arm. 5. Voluntary movements in extrapersonal space only are associated with activation of the parietal regions. These areas are assumed to provide information to the motor programming neurons about the demanded direction of motion in extrapersonal space in relation to proprioceptive reference systems. 6. The increase of rCBF in the auditory areas, the inferior frontal regions, and the frontal eye fields during the maze test were ascribed to the processing of auditory information. 7. Both tests are accompanied by a diffuse increase of the hemispheric blood flow (approximately 10%), which is assumed to be a parallel to the commonly known desynchronization of the EEG during mental work.