bluuebunny/crossref_metadata_2025 huggingface dataset:
Properties of concentrically organized X and Y ganglion cells of macaque retina
Authors: de Monasterio F. M.
Published: December 2017

1. Macaque retinal ganglion cells having concentrically organized receptive fields were classified as X- or Y-cells on the basis of the linearity or nonlinearity of their spatial summation to a "null" test of alternating contrast and drifting gratings. 2. When an alternating-phase, bipartite field positioned at the middle of the receptive field was used as a stimulus, X-cells had a null position, whereas Y-cells showed a doubling of the response frequency. When drifting sine-wave gratings of low contrast were used as a stimulus, X-cells showed a periodic modulation of their discharge having the same mean value for different spatial frequencies, whereas Y-cells showed a large increase in the mean value of their discharges. 3. X-cells had opponent-color responses that received cone-specific signals, i.e., center and surround responses were mediated by input from spectrally different types of cone, whereas Y-cells had broad-band spectral responses receiving mixed-cone signals, i.e., center and surround responses were totally or partly mediated by input from the same type(s) of cone. In most Y-cells, the spatially opponent responses from the center and the surround were mediated by the same types of cone and were thus spectrally nonopponent; other Y-cells showed spectral opponency, since one of the types of cone mediating responses of one region of the receptive field (e.g., center) was absent in the responses of the other region (e.g., surround). 4. X- and Y-cells projected to the lateral geniculate body. Opponent-color X- and Y-cells did not project to the superior colliculus, whereas a fraction of spectrally non-opponent Y-cells projected to this structure. 5. X-cells tended to have longer conduction latencies, less transient responses to small stimuli, and a more central retinal distribution than Y-cells; these differences, however, represented tendencies and not invariant properties. 6. The results show that the X/Y dichotomy of ganglion cells is present in the retina of macaques and indicate that the degree of the linearity of spatial summation of incoming cone signals to the cells is related to the degree of cone specificity of spectral inputs to the receptive-field mechanisms.
Acoustic input to single neurons in pulvinar-posterior complex of cat thalamus
Authors: Phillips D. P. , Irvine D. R.
Published: December 2017

1. Extracellular microelectrode recordings have been made of 429 single neurons in the pulvinar-posterior (Pul-PO) complex and adjacent regions of the thalamus of cats anesthetized with either sodium pentobarbital or alpha-chloralose. Controlled acoustic stimuli were presented by sealed systems incorporating probe microphone assemblies. 2. Neurons in pulvinar, lateralis posterior, and nucleus posterior were unresponsive to acoustic stimulation. Few cells in medial PO were observed to receive acoustic input, while sensitivity to tonal stimuli was a general feature of driven cells in other PO divisions. 3. Cells in lateral PO were generally sharply tuned to stimulus frequency, while the majority of cells in magnocellular medial geniculate and intermediate division of PO were broadly tuned. 4. Neurons in lateral PO and magnocellular medial geniculate had short response latencies to acoustic stimulation. Cells in intermediate division of PO were more often long latency. 5. Divisions of PO could not be differentiated on the basis of their binaural properties. Cells receiving excitatory input from solely the contralateral ear (E/O) or fros with onset discharge patterns showed occlusive binaural interaction properties. For cells with multiple-component discharge patterns, individual response components frequently had different patterns of binaural input and/or interaction. 6. On the basis of their discharge patterns, short latency, and frequency-tuning properties, it is suggested that lateral PO and magnocellular medial geniculate might derive their acoustic input from different divisions of the inferior colliculus. In contrast, the long latencies of units in PO intermediate division suggests a corticofugal input. 7. These data support anatomical parcelations of the Pul-PO complex, and the suggestion that this complex might provide acoustic input to the association cortices is evaluated.
Importance of corpus callosum for visual receptive fields of single neurons in cat superior colliculus
Authors: Antonini A. , Berlucchi G. , Marzi C. A. , Sprague J. M.
Published: December 2017

1. Section of the posterior two-thirds of the corpus callosum eliminates almost completely the response of superior colliculus (SC) neurons to stimulation of the contralateral eye in split-chiasm cats. On the contrary, the responsiveness of SC neurons to stimulation of the contralateral eye is not abolished by a transection of the posterior and tectal commissures leaving the corpus callosum intact. The callosal section also reduces the number of SC receptive fields abutting the vertical meridian in the ipsilateral eye of split-chiasm cats. 2. In cats with intact optic pathways, a similar callosal section abolishes the SC representation of the ipsilateral visual field in the ipsilateral eye and also reduces the number of receptive fields adjoining the vertical meridian in the same eye. In the contralateral eye, the SC representation of the ipsilateral visual field is reduced in extension to about one-fifth of that seen in cats with intact commissures. 3. The results suggest that the corpus callosum is the main pathway for cross-midline communication of visual information at not only the cortical, but also the midbrain level. The corpus callosum may subserve this function because it contains uninterrupted crossed corticotectal projections or because it transmits visual information from one hemisphere to contralateral cortical areas projecting ipsilaterally to SC. The latter hypothesis is more likely but, in any case, the findings imply that the lack of interhemispheric transfer of visual learning in cats with a chiasmatic and callosal section may depend on a midline disconnection of both subcortical and cortical visual centers. 4. The corpus callosum is also responsible for the representation of the ipsilateral visual field of the ipsilateral eye in the cat SC. The SC representation of the ipsilateral visual field in the contralateral eye is due, in minimal part, to direct retinotectal connections from temporal retina and, for the largest part, to the corpus callosum. 5. Finally, the corpus callosum contributes to the representation of the contralateral visual field near the vertical meridian of the temporal retina in both split-chiasm and normal cats. This is probably due to the scarcity of direct retinotectal projections from this part of the retina and to their supplementation by corticotectal neurons influenced by the callosal afferents.
Responses of single units in sixth lumbar dorsal root ganglion of female rats to mechanostimulation relevant for lordosis reflex
Authors: Kow L. M. , Pfaff D. W.
Published: December 2017

1. The activity of single units (n = 312) was recorded from dorsal root ganglion L6 in female rats; 84% received input from cutaneous mechanoreceptors. 2. Among cutaneous mechanoreceptive units (n = 263), 22% responded to individual guard hair movement, 18% to down hair, 11% to clitoral hair, and 14% to stimulation of tylotrich hair-haarscheibe (type I) receptors, 5% responded to punctate skin deformation, but not hair movement of pressure, and 18% responded to pressure. 3. No significant differences between estrogen-treated and untreated ovariectomized rats were observed in receptive-field size, or von Frey hair, or pressure threshold of any given type of unit. 4. The lordosis reflex of female rats is triggered by pressure, but not hair deflection, on skin regions innervated by dorsal root L6 (10). Stimulation from the male rat mounting would cause a barrage of action potentials from most of the unit types identified here, but only pressure units and type I units gave sustained responses to a lordosis-triggering type of pressure stimulation.
Voltage-modulated membrane resistance in coupled leech neurons
Authors: Zipser B.
Published: December 2017

1. Resistive interactions have been studied between two pairs of large identifiable neurons in ganglion 6 of the leech CNS, called the lateral and rostral cells. Both are motor neurons causing penile eversion. 2. Lateral and rostral neurons have different membrane resistance properties. Input resistances of lateral neurons are virtually constant. By contrast, membrane resistances of rostral neurons are highly voltage dependent. When depolarized from resting potential to firing level, a rostral neuron's input resistance can increase 10-fold, from 30 to 300 Momega. 3. Voltage-dependent membrane characteristics of rostral neurons cause resistive interactions with lateral neurons to be nonlinear. DC potentials evoked in lateral cells are transmitted to rostral cells with an efficiency varying over a 10-fold range. Hyperpolarizing coupling is weak, with coupling factors of about 0.03. Depolarizing coupling factors increase progressively with increasing lateral neuron depolarization, reaching values of up to 0.3. 4. Membrane resistance changes in rostral neurons accompany lateral to rostral cell interactions. Input resistances increase during depolarizing and decrease during hyperpolarizing coupling potentials. The lateral to rostral cell junctional resistance is high and invariant, as evidenced by uniformly weak coupling in the reverse direction, from rostral to lateral neurons. 5. In conclusion, asymmetries in lateral to rostral cell interaction are based on postsynaptic rather than junctional resistance changes. The impact of the lateral onto the rostral cell's excitability contains a nonlinear component besides the usual linear additive one. As in conventional resistive coupling, depolarizing coupling potentials raise the rostral neuron closer to its voltage threshold. But more significantly, depolarizing coupling potentials lower the rostral neuron's current threshold because increases in resistance proportionately reduce the amount of excitatory current needed to reach firing level. Thus, the resistance change acts to amplify the input signal efficiency. In addition to the static changes in current threshold, the reostral neuron also changes dynamically. Membrane resistance increases lead to increases in space constant shrinking the neuron's electrical lenght. 6. Other properties of the network have been analyzed. The pair of lateral neurons is strongly coupled, whereas the pair of rostral neurons is weakly coupled, the coupling factors are 0.3 and 0.05, respectively. Hyperpolarizing membrane time constants for the lateral and rostral neurons are estimated to be between 100 and 200 ms. Time constants of depolarized rostral neurons are significantly larger.
Supplementary motor area in the monkey: activity of neurons during performance of a learned motor task
Authors: Brinkman C. , Porter R.
Published: December 2017

1. Recordings were made of the natural discharges of neurons in the supplementary motor area (SMA) of conscious monkeys trained to perform stereotyped motor task, pulling a horizontal lever, with either hand. 2. Of the total population of cells, 80% showed modulation of their activity during particular movements of either limb. Many cells had a similar pattern of modulation regardless of whether the contralateral or ipsilateral hand was used. Of the remaining 20%, some cells were related to leg or body movements or to visual experience. 3. Cells whose activity was related to movements of distal joints were found in approximately equal numbers to those whose discharges occurred with proximal movements. 4. Only 5% of cells tested sent their axons into the pyramidal tract, and only 14% of units investigated showed responses to passive manipulation of the limbs. The effective afferent input usually was of a rather complex kind. 5. The findings suggest that the discharges of a large number of neurons in SMA are changing during particular movements of either arm, and that only a small number of cells receive peripheral afferent sensory input. These results contrast with those obtained in the primary motor area and suggest a different role for SMA in the control of movement.
Concept of neuron types in gustation in the rat
Authors: Woolston D. C. , Erickson R. P.
Published: December 2017

1. In taste neurophysiology, from Pfaffmann's (49, 50) pioneering work until the present, the possibility of types of neurons corresponding in some sense with the "primary" taste qualities of Henning (33) has been entertained: recently types of gustatory neurons in peripheral nerves have been established according to which of the four classical stimuli is the "best stimulus." However, considerable variation occurs in the response profiles within neurons classified as belonging to the same type. The purpose of this research is to determine, using mathematical techniques where appropriate, if the within-type variation is spurious or, instead, indicates the absence of a typology of taste neurons. The data used were counts of the spike discharges of 50 individual taste neurons in the nucleus of the solitary tract of the rat, evoked by 32 diverse chemical stimuli. 2. Using as input the matrix of Pearson r correlation coefficients calculated for the responses of all pairings of neurons to all stimuli, multidimensional scaling analysis revealed a two-dimensional space in which no clear groupings of neurons occurred. 3. In a hierarchical cluster analysis of the neuron response profile similarities, no evidence of grouping was found, suggesting a more-or-less continuous variation among neurons. 4. When the organization of the 32 stimuli utilized was studied by the same techniques, no clear evidence for stimulus types was found, although the possibility of two stimulus types--"sweet" and "nonsweet"--was raised. 5. Construction of a joint neuron-stimulus space supported a spatial model of taste neuron-stimulus interaction, while analysis of the number and pattern of high correlations among neurons--even after allowance for attenuation due to measurement error--failed to support the notion of types of taste neurons with identical response profiles. 6. Aspects of the logical role of types of neurons in gustatory coding were discussed, and the results and methods of the present investigation were related to classification schemes for neurons in general. Suggestions for a formal taxonomy of neurons were given. 7. It should be emphasized that the present study and conclusions are of second-order, CNS neurons, whereas the studies advocating the presence of neurons types were of peripheral neurons. Taken together, the implication to be drawn from these studies is that if neural types do exist in peripheral taste nerves, the typology is lost at the first synapse and is thus unavailable to the CNS for coding purposes, at least in the rat.
Effects of microlesions of dorsal cap of inferior olive of rabbits on optokinetic and vestibuloocular reflexes
Authors: Barmack N. H. , Simpson J. I.
Published: December 2017

1. Discrete, unilateral, electrolytic lesions of the dorsal cap of the inferior olive were made in rabbits in an attempt to assess the effect on eye movements of removal of a visual climbing fiber input to the fluocculus. The position of the lesioning electrode within the dorsal cap was adjusted on the basis of the field potential evoked by flash stimulation of the contralateral eye. 2. Electrophysiological and anatomical evidence confirmed that the microlesions of the dorsal cap destroyed 10-80% of olivary cells, but cause only slight damage to the olivocerebellar pathway originating from the contralateral dorsal cap. 3. The immediate effect of the microlesions was a spontaneous, conjugate drift of the eyes to the side contralateral to the lesion. The effects of the microlesions on eye movements were further examined using reflexes evoked by vestibular and optokinetic stimulation. 4. Postoperatively, the vestibuloocular reflex (VOR) gain was not modified, but there was a marked VOR velocity bias to the contralateral side. This velocity bias was most pronounced at low stimulus frequencies (0.02-0.05 Hz, +/- 10 degrees) and was minimal at stimulus frequencies above 0.5 Hz. 5. Monocular, sinusoidal optokinetic stimulation with a large contrast-rich visual target evokes, in normal rabbits, a conjugate asymmetric following response with a higher eye velocity for target movement from posterior to anterior. Following damage to the dorsal cap, the asymmetry of this optokinetic reflex was reversed when the target was presented to the eye contralateral to the lesion. With monocular, constant-velocity optokinetic stimulation delivered to the contralateral eye, the optokinetic gain for movement in the posterior to anterior direction was decreased. 6. These data suggest that visual climbing fibers are part of a feedback loop that reduces retinal slip of low velocity. The relatively low discharge rate of climbing fibers would seem appropriate to ecode continuously retinal slip of low velocity and to influence low-velocity eye movements.
Corrigenda for Luxotonic responses of units in macaque striate cortex
Authors: Kayama Yukihiko , Riso Donald R. , Bartlett John R. , Doty Robert W.
Published: December 2017

Page 1504: Yukihiko Kayama, Donald R. Riso, John R. Bartlett, and Robert W. Doty, “Luxotonic responses of units in macaque striate cortex.” The sentences beginning on the second line, left-hand column should read: “In either case the usual response was a large change, either enhancement or suppression, which followed immediately on the change in illumination. Commonly, the rate of discharge then gradually…” Page 1509: the last sentence of the legend to Fig. 14 should read, “Unit encountered 2 mm beneath dura mater in right operculum about 15 mm from midline, i.e., in striate cortex receiving projection from about 3° from center of visual field.”
An intracellular study of chemosensory fibers and endings
Authors: Hayashida Y. , Koyano H. , Eyzaguirre C.
Published: December 2017

1. The carotid body and its nerve, removed from anesthetized cats, were placed in physiological saline flowing under paraffin oil. The nerve, lifted into the oil, was used for either electrical stimulation or recording of the total afferent discharge. Intracellular recordings were obtained from individual nerve fibers and endings within the carotid body. The recording sites were identified by injecting Procion yellow through the intracellular electrodes; the tissues were then prepared for histology and observed with episcopic fluorescence or Nomarski optics. 2. Intracellularly recorded chemosensory fibers conducted at 1.1-30 m/s and usually displayed action potentials of regular amplitude. At times, however, some spikes become partially blocked while others maintained their original amplitude. "Natural" (hypoxia) or chemical (ACh or NaCN) stimulation induced different patterns of frequency changes of the large and small action potentials. This indicated nerve fiber branching at some distance from the recording site. 3. Intra- and extracellularly recorded spikes were blocked in 0 [Na+]0 by tetrodotoxin (TTX) or procaine. 4. During chemical stimulation, a slowly occurring depolarization (receptor or generator potential) was recorded intracellularly from the afferent fibers. It developed concomitantly with the increase in discharge. 5. Impalement of single nerve terminals (histologically identified) showed numerous "spontaneous" depolarizing potentials (SDPs) that had a mean amplitude of 5.6 mV, a mean duration of 46.1 ms, and nearly random distribution. They increased in frequency and summated during chemical stimulation. SDPs originated from either the site of recording or from neighboring areas. When the SDPs attained a certain amplitude, they seemed to give rise to action potentials. Also, relatively well developed or partially blocked spikes (apparently originating elsewhere) were recorded from single nerve terminals. 6. The receptor (generator) potential of chemosensory receptors appears to be an integrated response formed by multiple activity originating in different nerve endings.
Corrigenda for Passive electrical constants in three classes of hippocampal neurons
Authors: Brown Thomas H. , Fricke Russell A. , Perkel Donald H.
Published: December 2017

Page 815: Thomas H. Brown, Russell A. Fricke, and Donald H. Perkel, “Passive electrical constants in three classes of hippocampal neurons.” The sentence beginning six lines below equation 8, right-hand column, should read: Although equation 8 was originally derived assuming an infinite electrotonic length, the resultant biases are small when rho is small (11, 32), as described below.
Behavior of cutaneous mechanoreceptors recorded in mandibular division of Gasserian ganglion of the rabbit during movements of lower jaw
Authors: Appenteng K. , Lund J. P. , Seguin J. J.
Published: December 2017

1. The activity of cutaneous mechanoreceptors was recorded extracellularly in the mandibular division of the Gasserian ganglion of hemidecerebrate anesthetized rabbits. Fifty-four hair follicle afferents and 80 skin mechanoreceptor afferents were functionally identified. Their receptive-field characteristics were described and their activity patterns were recorded while the jaw was displaced by hand in the vertical, horizontal, and anterior-posterior directions, and during masticatory movements. 2. All hair follicle afferents were classified as rapidly adapting, whereas skin afferents could be divided into two categories: rapidly adapting and slowly adapting. Rapidly and slowly adapting receptors were found in all regions of the mandibular skin. Only one hair follicle afferent and four skin afferents fired spontaneously with the jaw at rest. 3. Fifty-eight percent (29/50) of the hair follicle afferents were activated by imposed displacement of the jaw and all of these tested also discharged during chewing. They were sensitive to movement in all three axes and their firing frequency was linearly related to the velocity, regardless of direction. 4. Only 10% (8/80) of the skin afferents were activated by imposed displacement of the jaw if their receptive fields were not directly contacted. Firing frequency was not well related to either the amplitude or velocity of movement. During chewing, the discharge frequency was variable but, in general, firing was restricted to the jaw-closing phase. Most skin afferents that were active during jaw movement had receptive fields close to the corner of the mouth. 5. The results are discussed within the context of a possible involvement of cutaneous afferents in kinesthesia and in the control of jaw movements. Hair afferents could make specific contributions to the appreciation of movement because their discharge pattern was clearly related to one of its parameters. The lack of activity of most skin afferents, as well as the absence of a strong correlation between the firing frequency of those that were active and the movement parameters, suggest that they do not make specific contributions to the awareness of movement. 6. Hair and skin afferents may also make different contributions to the control of ongoing movements. It is suggested that skin afferent activity during jaw closure may elicit a reflex reduction in the velocity or duration of this phase. Some evidence from other studies suggests that hair afferent activity may indirectly influence movement via effects on elevator fusimotor neurons.
Spectral bandwidths of color-opponent cells of geniculocortical pathway of macaque monkeys
Authors: de Monasterio F. M. , Schein S. J.
Published: December 2017

1. The spectral-response bandwidth and peak sensitivity of the responses of color-opponent retinal ganglion cells of the macaque monkey were examined in conditions of neutral adaptation. Color-opponent cells showed specific "signatures" in plots of response bandwidth versus wavelength of the peak sensitivity that allow for an acceptable estimate of the cone types whose signals mediate cell responses. 2. Averaged spectral bandwidths of color-opponent ganglion cells were compared with published data from color-selective neurons of subsequent levels of the geniculocortical pathway, including the extrastriate area termed V4. No significant differences were found between color-selective cells of the retina, dorsal lateral geniculate body, striate cortex, and V4. 3. The spectral location of the peak sensitivity of responses of the various types of color-opponent ganglion cells showed a relatively broad distribution, loosely clustering at some spectral loci. Comparison of such distribution with that of recently reported V4 cells response indicates that a remarkable scarcity of "blue/yellow" opponent responses in such reports. 4. In association with more recent electrophysiological studies of V4 cells, the results do not support current claims of a color specialization of this extrastriate area, and suggest lack of significant spectral tuning of the retinal output in, so far known, higher visual centers having color-selective cells.
Linear and nonlinear W-cells in C-laminae of the cat's lateral geniculate nucleus
Authors: Sur M. , Sherman S. M.
Published: December 2017

1. We used standard, single-cell recording techniques to study the response properties of 34 W-cells in the C-laminae of the cat's lateral geniculate nucleus. By W-cell, we mean a poorly responsive geniculate neuron that receives slowly conducting retinal afferents; these are quite distinct from geniculate X- and Y-cells. Our measurements included response latency to optic chiasm stimulation, plots of the receptive-field center, time course of response, and responses to counterphased, sine-wave gratings. This last measurement also involved the determination of contrast sensitivity, which is defined as the inverse of the contrast needed to evoke a threshold response at a particular spatial and temporal frequency of the grating. Many of these responses were compared to those of geniculate X- and Y-cells recorded in the A-laminae. 2. Each of the W-cells responded with a latency of at least 2.0 ms to optic chiasm stimulation, and most (76%) exhibited a latency of at least 2.5 ms. However, only 26 of these W-cells responded to visual stimuli, and these responses were weak or "sluggish," as has been reported previously. Receptive fields of these W-cells tended to be large, compared to those of X- and Y-cells, and included 11 on-center, 13 off-center, and 2 on-off center fields. 3. W-cells exhibited either linear (12 cells) or nonlinear (14 cells) spatial and temporal summation, as determined from their responses to counterphased, sine-wave gratings. Linearity of spatial summation was determined by measuring contrast sensitivity as a function of the grating's spatial phase. The linear W-cells' responses were sinusoidally phase dependent, and the nonlinear W-cells' responses were independent of spatial phase. Linearity of temporal summation was determined by the presence or absence of harmonic distortion in the response relative to the grating's counterphase rate. Linear W-cells responded chiefly at the grating's fundamental temporal frequency, whereas much of the nonlinear W-cells' responses occurred at the second harmonic of the grating's temporal frequency. Thus, nonlinear W-cells exhibited many of the characteristics previously described for Y-cells. 4. Spatial and temporal contrast-sensitivity functions were determined for seven linear and eight nonlinear W-cells. Overall sensitivity values of the linear and nonlinear W-cells were comparable, but these groups differed in terms of the nature of the response component (linear or nonlinear) that was more sensitive. 5. The linear W-cells in our sample included both tonic (comparable to the "sluggish-transient" type of retinal ganglion cells) types, while all nonlinear W-cells were phasic. Otherwise, no difference between linear and nonlinear W-cells was seen for latency to optic chiasm stimulation, receptive-field size, overall contrast sensitivity, responsiveness to visual stimuli, overall spatial resolution, or temporal resolution. 6...
Recovery of binocular function in kitten visual cortex
Authors: Levitt F. B. , Van Sluyters R. C.
Published: December 2017

1. This paper describes the results of an experiment designed to examine the ability of cells in the kitten's visual cortex to regain functional binocular connections following exposure to a brief period of visual deprivation. 2. Normal 4-wk-old kittens were exposed to a total of 12 h of optically induced strabismus over a period of 2 days, and single-unit recordings made the following day indicated that the proportion of striate cortex cells with binocular receptive fields had decreased sharply as a result of this episode of strabismic vision. 3. When these kittens were revived and allowed to experience a recovery period of normal binocular vision lasting either 3 or 7 wk, cortical binocularity returned to a normal level. 4. Statistical analysis revealed that the difference in the level of binocularity observed before and after the period of binocular recovery was highly significant, and comparison of the results from kittens allowed only a 3-wk recovery period with those from kittens allowed a 7-wk period indicated that a similar level of recovery was obtained in each group. 5. Histological reconstruction of electrode penetrations indicated that the recovery of binocular receptive fields occurred uniformly across all cortical laminae. 6. These data are discussed in terms of the results from previous recovery experiments, the relationship between cortical binocularity and the ability to maintain binocular fixation, and the possibility that subliminal cortical input plays a role in the recovery of functional binocular cells.
Response properties of visual cortical neurons in cats reared in stroboscopic illumination
Authors: Kennedy H. , Orban G. A.
Published: December 2017

1. The response properties of 182 units were studied in the primary visual cortices (155 in area 18 and 27 in area 17) in eight cats reared from birth in a stroboscopically illuminated environment (frequency, 2/s; duration, 200 microseconds). Multihistogram quantitative testing was carried out in 82 units (64 in area 18 and 18 in area 17). Two hundred three neurons recorded and quantitatively tested in areas 17 and 18 of the normal adult cat were used for comparison. 2. Spatial characteristics of receptive fields investigated using hand-held stimuli were found to be abnormal. The correlation between receptive-field width and eccentricity was lost in area 18 and consequently, receptive fields were significantly wider in area 18 subserving central vision. Cells could be classified according to the spatial characteristics of their receptive fields. There was a much smaller proportion of end-stopped cells in strobe-reared animals. Orientation tuning in the deprived animals was normal except for a small number of cells that showed no selectivity for stimulus orientation. 3. Compilation of velocity-response curves made it possible to classify areas 17 and 18 neurons into four categories: velocity low-pass, velocity broad-band, velocity tuned, and velocity high-pass cells. The proportion of velocity high-pass cells was reduced in area 18 subserving peripheral vision, as was the proportion of velocity-tuned cells in area 18 subserving central vision. 4. In the strobe-reared animal velocity sensitivity was somewhat different from that of the normal animal. Neurons in area 18 subserving the peripheral visual field failed to respond to fast velocities. Neurons in area 17 subserving the central visual field in strobe-reared animals responded to slightly higher velocities than in the normal animal. 5. In the deprived animals the number of neurons that were selective to the direction of motion was strongly reduced. The majority of neurons failed to show a selectivity for direction at all velocities. A number of neurons could be directional at some velocities but were unreliable, since they inverted their preferred direction with velocity changes. 6. Binocular convergence onto visual cortical cells was perturbed. In area 18 the majority of neurons were driven by the contralateral eye. In area 17 most neurons could be driven only by either the ipsilateral or contralateral eye. 7. Quantitative testing (of direction selectivity, sensitivity to high velocities, response latency, and strength) and qualitative testing (receptive-field width, end stopping, and ocular dominance) showed that the normal influence of eccentricity on functional properties was strongly reduced by strobe rearing.
Congruence of spatial organization of tactile projections to granule cell and Purkinje cell layers of cerebellar hemispheres of the albino rat: vertical organization of cerebellar cortex
Authors: Bower J. M. , Woolston D. C.
Published: December 2017

1. We compared the spatial pattern of shortest latency somatosensory (tactile) projections to the Purkinje cell (PC) layer and to the underlying granule cell (GC) layer in tactile areas of rat cerebellar cortex. Micro-mapping methods were used to sample single units in the PC layer and multiple units in the GC layer of both anesthetized and unanesthetized rats. Mechanical and electrical stimulation of the body surface were employed. Responsiveness of PCs to cutaneous stimulation was assessed by constructing histograms of simple spike activity and statistically comparing poststimulus activity to nonstimulated base-line PC activity. 2. We found that PCs respond to tactile stimulation with increases (7-10 ms) followed by decreases (8-15 ms) in simple spike activity. Increases in simple spike activity followed activation of the underlying GC layer by 1-4 ms, while decreases in simple spike activity were found 2-5 ms after GC layer activation. 3. PCs were found to have both excitatory and inhibitory receptive fields (RFs). Excitatory RFs were restricted to small areas of a single body part and for each PC were very similar or identical to the RFs of neurons in the immediately subjacent GC layer. Inhibitory PC RFs were larger, often containing more than one body part and for each PC, were only partially similar to the RFs of subjacent GCs. PC inhibitory RFs also often included body surfaces projecting to the nearby but not to the underlying GC layer. 4. Stimulation of a single peripheral locus resulted in small, distinct regions of PC layer excitation and inhibition. Areas of PC excitation overlie activated regions of the GC layer, while inhibited PCs overlie both activated and nonactivated GC regions. 5. We found PCs to be organized in groups or patches with respect to the specific body region that was capable of activating them (upper lip, lower lip, etc.). Adjacent patches of PCs often represented widely separated body parts. This pattern of PC layer activating RF projections was congruent with the pattern of excitatory RF projections to the underlying GC layer. 6. These results indicate that there is a vertical organization in GC-PC excitatory relations, while GC-induced PC inhibition is slightly more widely distributed. 7. Our finding that the patchlike activation of PCs is congruent with that of the underlying GC layer contrasts with the classical concept that PCs are activated by parallel fibers in a "beamlike" fashion from a patch of GCs. Thus, a reevaluation of the role of parallel fibers seems to us to be in order. 8. In conclusion, our results support the view that short-latency afferent tactile projections to both the GC and PC layers of cerebellar cortex are highly organized spatially. This specificity of body surface projections must be incorporated into modern views of the functional organization of cerebellar cortex.
Lateral interactions in absence of feedback to cones
Authors: Skrzypek J. , Werblin F.
Published: December 2017

1. The reversal potential of the surround response in cones was measured by inactivating the outer segment, polarizing the cone to different potential levels with extrinsic current, and flashing a full-field stimulus. This elicited a 3- to 4-mV depolarizing response at the normal -40-mV dark level. Its reversal potential was typically near -60 mV. 2. Cones were also polarized by a steady center light while flashing an annulus. The annular response was suppressed when the cone was polarized to near -60 mV. No reversal was measured, presumably because the maximum center light response could not exceed -60 mV. 3. Items 1 and 2 provide a method for measuring surround responses in cells post-synaptic to the cones in the absence of the surround response in the cones themselves; cone surround responses are suppressed although some horizontal cell surround responses are enhanced (item 6) at high center intensities that polarize the cones to near -60 mV. 4. Bipolar cells of both types (depolarizing and hyperpolarizing) generate a surround response that opposes the center response. In both bipolar cell types, the surround response is completely suppressed near center intensities that suppress the surround response in the cones. 5. Narrow-field horizontal cells behave like cones and bipolar cells; the depolarizing surround response is suppressed at high center intensities bright enough to suppress the cone surround response. At higher center intensities the surround response becomes hyperpolarizing, presumably due to direct coupling to peripheral horizontal cells. 6. Broad-field horizontal cells always hyperpolarize in response to surround illumination. The hyperpolarizing surround response is augmented at high center intensities, presumably because the depolarizing component, initiated in the cones, is suppressed, while the direct coupling to peripheral horizontal cells remains intact.
Adaptive changes in firing rates in goldfish auditory fibers as related to changes in mean amplitude of excitatory postsynaptic potentials
Authors: Kuno M.
Published: December 2017

Relationship between the firing rate in the auditory fibers and the amplitude of the excitatory postsynaptic potentials (EPSPs) that trigger afferent impulses was investigated. The unitary EPSPs and spike potentials were extracellularly recorded from the goldfish large auditory fibers by means of a microelectrode placed close to the distal terminals. The relation between the firing rate and the amplitude of the EPSPs was studied using a variety of stimulus conditions. The firing probability of phase-locked impulses was linearly related to the mean amplitude of the EPSPs determined for the same time bins. The same linear relation was applicable for the firings elicited by different intensities of sound and observed at various times after onset and also for the firings produced by applying step increments in intensity. The threshold amplitude of the EPSPs required for initiation of afferent impulses was unchanged in these different situations. Random changes in the amplitude of successively evoked EPSPs were found to underlie the probabilistic nature of the sequence of afferent firings. The present results indicate that the per stimulus adaptation and incremental and decremental responses, as observed in the firing probability of afferent impulses, are largely attributable to adaptive changes in the mean amplitude of the evoked EPSPs and not to changes in excitability of the auditory fibers.
Nerve fibers sensitive to ionic taste stimuli in chorda tympani of the rat
Authors: Frank M. E. , Contreras R. J. , Hettinger T. P.
Published: December 2017

Hypotheses about the peripheral basis for the sense of taste in mammals have been based to a considerable degree on the determined sensibilities of the nerve fibers in the chorda tympani of the rat to chemical stimulation of the anterior tongue. Yet, whether neuron types exist in this nerve, the nature of the basic mechanisms of taste reception that are tapped by this nerve and the form in which information about stimulus quality and intensity is transmitted to the central nervous system by this nerve are, at present, unresolved issues. These issues are addressed in the present study, which is a detailed analysis of the responses of rat chorda tympani nerve fibers that are sensitive to ionic stimuli; solutions applied to the anterior tongue included a range of concentrations of four chemical compounds (sucrose, sodium chloride, hydrochloric acid, and quinine hydrochloride) that represent widely different taste qualities to man or rat. Of the 44 nerve fibers sampled, 40 were stimulated most by one of the two ionic stimuli at test concentrations reported to be equally effective: 21 fibers were most responsive to 0.1 M NaCl and named N units; 19 fibers were most responsive to 0.01 M HCl and named H units. Although many N and H units responded to both HCl and NaCl, the distribution of NaCl-HCl response ratios was bimodal, indicating there are two varieties of units sensitive to ionic taste stimuli in the rat chorda tympani. Sucrose (0.5 M) affected 4 of the nerve fibers and was the most effective stimulus for 3 of them; 0.02 M quinine affected 13 of the fibers but 10 of these were H units. H units were less "specifically tuned" than N units; they were more likely to respond to several of the chemicals. Although the absolute sensitivity to NaCl in N units or to HCl in H units varied more than 10-fold, the relative effects of the four stimuli (response profiles) were generally similar for units of a given type. Exceptions occurred when H unit responses to NaCl or quinine were suppressed by prolonged effects of preceding HCl stimulation. The similarity in response profiles is reflected in high and significant correlations between responses to each pair of effective stimuli across either H or N units.(ABSTRACT TRUNCATED AT 400 WORDS)
Nocifensive responses to cutaneous thermal stimuli in the cat: stimulus-response profiles, latencies, and afferent activity
Authors: Casey K. L. , Morrow T. J.
Published: December 2017

Rapid<onset thermal pulses (38 degrees C X s<1) ranging from 43 to 60 degrees C (adapting temperature, 38 degrees C) were applied by contact thermodes to the shaved outer thighs of 29 partially restrained cats while they were eating (coincident stimuli) or between eating periods (noncoincident stimuli). The stimulus<associated probability and latency of three putative nocifensor responses were determined: interruption of eating or of exploration for food, hindlimb movement, and vocalization. These behavioral responses terminated the stimulus. An analysis of response trends and latencies supports the interpretation that these are unlearned escape responses to noxious stimuli. Response threshold was defined as the lowest temperature at which the average response probabilities at the test temperature and at 38 degrees C were outside one another's 95% confidence limits. Average threshold varies with the type of response and the behavior at the time of stimulation. Noncoincident stimuli elicit both interrupt and movement responses at 47 degrees C and vocalization at 53 degrees C. Coincident stimuli also elicit interrupt responses at 47 degrees C but are associated with an increased hindlimb movement threshold (51 degrees C) and vocalization threshold (55 degrees C). The lowest threshold determined for an individual cat was 43 degrees C. Response probability increases as a nonmonotonic function of stimulus intensity. Maximum sensitivity to increases in temperature occurs at stimulus intensities between 50 and 55 degrees C. Above 55 degrees C, some cats show an attenuation of response sensitivity. Special tests failed to reveal any evidence that receptor sensitization or suppression affected the stimulus<response profiles. The average response latency for all behaviors of all cats is 2.3 +/- 0.12 (SE)s from the onset of the stimulus pulse plateau. Most responses occurred within 2.5 s. No significant relationship was found between response latency and type of response or stimulus intensity. The composition and time of onset of heat-evoked afferent activity in the lateral femoral cutaneous nerve was investigated in six cats by colliding antidromic A-delta- and C-fiber volleys with the orthodromic discharge evoked by the thermodes used in the behavioral studies. There was no evidence that noxious thermal pulses evoked activity in A-delta-afferents, but C-fibers could be shown to become active at approximately 46 degrees C, at or before the onset of the thermal pulse plateau.(ABSTRACT TRUNCATED AT 400 WORDS)
Topographic factors in distribution of homonymous group Ia-afferent input to cat medial gastrocnemius motoneurons
Authors: Lucas S. M. , Binder M. D.
Published: December 2017

Experiments were performed to determine whether the topographic relationships between muscle spindles and their surrounding extrafusal fibers are preserved in the pattern of homonymous, monosynaptic connections from Ia-afferents to motoneurons. The medial gastrocnemius (MG) muscle of adult cats was chosen as a model system because previous studies have shown that its muscle nerve divides into several branches, each of which innervates a distinct muscle compartment (20, 27, 28, 38), and that the Ia-afferent fibers innervating muscle spindles within a compartment are found in the same nerve branch (27, 28). Thus, we could make intracellular recordings from MG motoneurons, determine which intramuscular compartment they innervated, and then compare the synaptic input they received from Ia-afferents innervating the same compartment with that which they received from Ia-afferents innervating different compartments. Our results indicate that homonymous Ia-afferent input is "topographically weighted" within the MG motor nucleus such that afferents innervating a given intramuscular compartment exert relatively greater synaptic effects in motoneurons that project to the same compartment than in other homonymous motoneurons. The degree of topographic weighting was quite variable in the different experiments but appeared more prominently in experiments in which a high proportion of the motoneurons studied were characterized by high-rheobase values and low input resistances. This suggests that topographic factors may exert more influence on the distribution of Ia-afferent input to large motoneurons than to small motoneurons. In the DISCUSSION, the extent of topographic weighting within the homonymous motoneuron pool is compared with weighting across synergist motoneuron pools, and alternative models of topographic weighting are proposed and evaluated.