AIMTo explore the cerebral cortex mechanism of visceral nociceptive sensation and its characteristics on the cell level, we investigated the membrane electrical properties of 176 stimulus-relative neurons of greater splanchnic nerve (GSN) in anterior cingulate gyrus (ACG) of 20 adult healthy cats.

METHODSWe used intracellular recording techniques of glass microelectrode and injected polarizing current into the neurons in ACG.

RESULTSAmong 176 neurons, 148 were visceral nociceptive neurons (VNNs) and 28 non-visceral nociceptive neurons (NVNNs). The membrane resistance (Rm), time constant (tau), membrane capacity (Cm), and the I-V curve of both VNNs and NVNNs in ACG were significantly different. The discharge frequency and amplitude of both VNNs and NVNNs produced by injecting depolarized current were different, too.

CONCLUSIONThe results suggest that structure of cell membrane, volume of the soma, and other aspects of morphology between VNNs and NVNNs in ACG may have significant differences. The results also might provide progressively experimental evidence for specific theory of pain sensation.

Animals ; Cats ; Gyrus Cinguli ; cytology ; physiology ; Membrane Potentials ; Nociceptors ; physiology ; Splanchnic Nerves ; physiology ; Visceral Afferents ; physiology

In this research, we compared the visual neuron responses for LGN, A18 and PMLS of old and young cats with extracellular single-neuron recording techniques. We used firing rate vector to characterize information, and response irregularity of cells to evaluate the degeneration of visual characters. Response irregularity is characterized by means of the two coefficients of variation of firing rate vectors: Cv and Cv2. We found that there was no significant change of the response irregularity in LGN areas during the aging process from young to old cats. But in the other two areas, neurons of old cats exhibited significantly larger response irregularity than those of young cats. The result indicated that the information processing function of advanced visual cortex was impaired by aging. This result also provids a reference for the research of the other neuronal system changes during aging process.
Action Potentials ; physiology ; Aging ; physiology ; Animals ; Cats ; Neural Conduction ; Neurons ; physiology ; Visual Cortex ; physiology

Urodynamic evaluation is an invasive and uncomfortable procedure that can cause physical distress and is difficult to perform in uncooperative patients. The aim of this study was to evaluate the effects of consciousness on urodynamic evaluation in an animal model. Repeated cystometry, electromyogram, and measurement of serum cortisol concentrations were performed in female cats under conscious (CON), conscious sedation (CS) and deep anesthesia (DA) conditions. Urodynamic evaluation showed that there were no statistical differences in maximum detrusor pressure or bladder capacity observed among the three conditions. Under the DA condition, but not the CON and CS conditions, bladder contraction was accompanied by an un-relaxed anal sphincter. Residue urine volume significantly increased in the DA condition compared to the CON and CS conditions. The levels of serum cortisol significantly increased after performing urodynamic evaluation under the CON condition, whereas these levels were not significantly increased under the CS and DA conditions. This study showed that conscious sedation has no adverse effects on the urodynamic variables, and that it significantly reduces distress in cats undergoing the examination. These results may provide novel insights for performing urodynamic studies in uncooperative patients.
Animals ; Cats ; *Consciousness ; Female ; Hydrocortisone/blood ; Models, Animal ; Urinary Bladder/physiology ; Urination/physiology ; Urodynamics/*physiology

PURPOSE: The purpose of this study was to investigate the effects of contrast display exposure on neuronal directional and spatial frequency tuning. Neuronal responses were recorded from ninety-four neurons in cortical areas 17 and 18 in two adult cats. METHODS: A multi-channel microelectrode was implanted in cortical areas 17 and 18 of two paralyzed and anaesthetized cats. Various drifting sinusoidal grating contrast displays were presented to one of the cats' eyes in the visual field. Contour plots based on the neuronal responses to the drifting sinusoidal grating displays using various contrasts (i.e., 0.4, 0.7, and 1.0) and velocities (i.e., 4.6, 13.9, 23.1, 32.3, 41.5, 50.8, and 60.0 deg/sec) were plotted as a function of the spatial frequency and the direction associated with each velocity and contrast used. RESULTS: Five parameters were extracted from these contour plots: 1) optimum response, 2) preferred direction, 3) optimum spatial frequency, 4) directional tuning width, and 5) spatial frequency bandwidth. To determine the optimal velocity, each parameter was plotted against each of the specific display contrasts used, and a 'best fit' line was established. Response amplitudes were dependent on the type of contrast utilized; however, the spatial frequency and directional tuning properties were stable for the cortical neurons assessed. CONCLUSIONS: The results of the presentation of different contrasts on neuronal directional and spatial frequency tuning are consistent with behavioral results when medium and high contrast displays are used.
Animals ; Cats ; Contrast Sensitivity/*physiology ; Electrophysiological Phenomena ; Orientation/physiology ; Photic Stimulation/methods ; Sen ; Space Perception/physiology ; Visual Cortex/cytology/*physiology

OBJECTIVETo investigate the efferent pathway from the dorsal raphe nucleus to the inner ear.

METHODSEleven adult cats weighing 2.0 - 3.0 kg were used. The animals had no middle-ear disease and their auricle reflex was sensitive to sound. They were divided into experimental group (8 cats) and control group (3 cases). The fluorescent tracer cholera toxin subunit-B (CTB) was injected into cat cochlea and the CTB-labelled neurons of dorsal raphe nucleus (DRN) were identified using an immunofluorescence technique after a survival period of 7 days. For studying other fluorescence labelling, the sections containing CTB-labelled neurons were divided into four groups and incubated in antisera directed against tyrosine hydroxylase (TH), serotonin (5-HT), gamma-aminobutyric acid (GABA) and dopamine B-hydroxylase (DBH), respectively. Single-and double-labelled neurons were identified from the DRN.

RESULTS(1) A subpopulation of dorsal raphe nucleus (DRN) neurons were intensely labelled with CTB and these CTB-labelled neurons were densely distributed in a dorsomedial part of the DRN; (2) Four immunolabelling, TH, 5-HT, GABA and DBH were presented throughout the DRN. Of the total population of CTB-labelled neurons, 100% were TH-labelled neurons (double labelling) and no double-stained neuron with 5-HT, GABA and DBH was observed in the DRN.

CONCLUSIONSThere was a projection from DRN to the inner ear and this pathway might be a dopaminergic projection.

Animals ; Cats ; Ear, Inner ; innervation ; metabolism ; Efferent Pathways ; Neurons ; metabolism ; physiology ; Raphe Nuclei ; metabolism ; physiology

Using intracellular potential recording technique in vivo, a series of hyperpolarizing and depolarizing currents at different intensities with a 50-ms duration were injected to somatic nociceptive neurons (SNNs) and somatic non-nociceptive neurons (SNNNs) in the anterior cingulate gyrus (ACG) of cats. The membrane electrical responses of the neurons were recorded, and the membrane electrical parameters of the neurons were calculated for comparative study on membrane electrical properties of SNNs and SNNNs of the ACG. A total of 188 ACG neurons from 57 cats were recorded. Among the 188 neurons, 172 (91.5%) and 16 (8.5%) were SNNs and SNNNs, respectively. The I-V curves of SNNs and SNNNs in the ACG were "S" shapes. When the absolute value of injected current intensity was less than or equal to 1 nA (≤ 1 nA), the I and V of I-V curves of both SNNs and SNNNs were linearly correlated (rSNNs = 0.99, rSNNNs = 0.99). When the absolute value of injected current intensity was more than 1 nA, both SNNs and SNNNs showed a certain inward or outward rectification behavior. Compared with SNNNs, SNNs had stronger rectification and lower adaptability (P < 0.01). With the increase of injected current intensity, the changes of frequency of discharges of SNNs were higher than those of SNNNs. In addition, the membrane resistance (Rm), the membrane capacity (Cm) and the time constant (τ) of SNNs were larger than those of SNNNs (P < 0.05 or P < 0.01). The differences in the membrane electrical properties between SNNs and SNNNs in the ACG suggested the disparity in neuronal cell size and cell membrane structure between them. The results of this study provided the experimental basis for deeply elucidating the mechanisms of somatic nociceptive sensation and characteristics on the membrane electrical aspects of ACG neurons.
Animals ; Cats ; Gyrus Cinguli ; cytology ; Membrane Potentials ; Neurons ; physiology ; Nociceptors ; physiology

The aim of the present study is to explore the role of anterior cingulate gyrus (ACG) in bilateral cerebral cortex in visceral nociceptive sensation. Electrical stimulation of greater splanchnic nerve (GSN) was used as visceral nociceptive stimulus, and intracellular recording techniques in vivo was used to record and analyze the responses to stimuli and spontaneous electric activities of the neurons in the bilateral ACG. According to the responses to electrical stimulation of GSN, the neurons in the bilateral ACG were divided into GSN-stimulus-relative neurons (GSRNs) and GSN-stimulus-irrelative ones. According to the characteristics of the evoked responses to electrical stimulation of the GSN, GSRNs could be further classified into visceral nociceptive neurons (VNNs) and non-visceral nociceptive neurons (NVNNs). VNNs included specific visceral nociceptive neurons (SVNNs) and non-specific visceral nociceptive neurons (NSVNNs). The results showed that the percentage of GSRNs in the contralateral ACG (38.18%) was significantly higher than that in the ipsilateral ACG (29.49%, P<0.01), suggesting although GSN afferent fibers project to bilateral ACG, they mainly project to the contralateral ACG. Compared with ipsilateral ACG, contralateral ACG possessed lower proportion of SVNNs and higher proportion of NSVNNs (P<0.01). The absolute values of resting potentials (RP) of GSRNs, VNNs, NVNNs and SVNNs in ipsilateral ACG were less than those of corresponding neurons in contralateral ACG. However, there were no significant differences in the absolute values of RP of NSVNNs between ipsilateral and contralateral ACG. There were no significant differences in modes, frequencies and amplitudes of spontaneous electric activities of VNNs and NVNNs between ipsilateral and contralateral ACG. Additionally, the percentage of neurons having spontaneous electric activities from VNNs was significantly higher than that from NVNNs, which indicated that the excitability of VNNs was higher than that of the NVNNs in bilateral ACG. These results suggest that the patterns and degrees of the responses to nociceptive GSN-stimulation of the ipsilateral and contralateral ACG are different, thus providing new experimental data for the asymmetry of functions of the bilateral brain.
Animals ; Cats ; Electric Stimulation ; Evoked Potentials ; physiology ; Female ; Gyrus Cinguli ; physiology ; Male ; Nociceptors ; physiology ; Viscera ; innervation ; Visceral Pain ; physiopathology

The retinotopic topography of area 17 in cats was measured by optical imaging based on intrinsic signals. When stimulated with two neighboring gratings oriented orthogonally each other, which were positioned respectively in the upper and lower visual fields, one piece of cortex that had the retinal projection corresponding to the area around the border of the two stimulus gratings became blurred in the resultant function orientation map, because the neurons in this site received excitatory signals from both the horizontal and the vertical gratings via indirect ways. This functional map of the same cortex was compared with that elicited only by a horizontal or vertical grating stimulation in the whole visual field. Accordingly, the accurate position of the retinotopic eccentricity of the cortex in visual field can be demarcated by calculating the cross correlation coefficient of the two functional maps. Furthermore, compared with the electrophysiological measure of receptive fields of single cortical neurons, the retinotopic eccentricities revealed by optical imaging were identical. This experiment provides a fast and relatively accurate method to calculate the retinotopic eccentricities in a large cortical area of the visual cortex.
Animals ; Brain Mapping ; methods ; Cats ; Evoked Potentials ; Retina ; physiology ; Tomography, Optical ; Vision, Ocular ; physiology ; Visual Cortex ; physiology ; Visual Pathways ; physiology ; Visual Perception ; physiology

In three isolated organs, spleen, cardiac and skeletal muscles, kinetic studies of red cell washout were carried out by using perfusion of the cell-free, oxygenated Ringer's solution. It is found that in each organ there are slow components for red cells to be emptied out from the vascular lumens ranging 30 to 50 minutes as the desaturation half-time. The slowest decay constants (K) are -1.48 X 10(-3) for spleen, -2.33 X 10(-3) for gastrocnemius muscle, and -4.0 X 10(-3) for cardiac muscle.
Animal ; Cats ; Coronary Vessels* ; Erythrocytes/physiology* ; Microcirculation ; Muscles/blood supply* ; Spleen/blood supply*

OBJECTIVETo use infrared thermography to take cat cerebral cortical temperature in order to visualize the temperature of its entire cerebral cortex as an image.

METHODSAfter performing craniotomy for exposure of cerebral hemispheres in 52 cats, their cortical temperatures were displayed and analyzed by computerized infrared thermovision.

RESULTSThe temperature distribution of the cerebral cortex was uneven, with a maximum difference of 2.3 degrees C among different cortical areas. The temperature in the cortical anterior-inferior area (including the Ant. Ectosylvian, the lower section of Mid. Ectosylvian and the Ant. Sylvian) was higher compared to the temperature in the posterior-super-parts (Post. Suprasylvian, Mid. Suprasylvian, Post. Lateral and Ant. Lateral). Locations with higher or lower temperatures showed little change within three days after craniotomy, and the cortical temperature held steady.

CONCLUSIONThe use of cortical infrared thermo-images for display of cat cortical temperature is possible and has many advantages over traditional methods. This new neuroimaging method has a practical value in neurological research.

Animals ; Body Temperature ; Cats ; Cerebral Cortex ; physiology ; Electroacupuncture ; Female ; Infrared Rays ; Male ; Thermography