Unrestrained Cats Research Articles

Somatomotor and cardiorespiratory responses to basal ganglia stimulation in cats

The electrical stimulation of the neural elements within the basal ganglia circuitry caused characteristic somatomotor activities and changes in arterial blood pressure (BP), heart rate (HR), and respiratory rate (RR) in conscious, unrestrained cats. A highly constant pattern of responses was elicited by stimulating repeatedly at the same locus, but significant differences occurred among responses obtained from identified parts of the basal ganglia. Stimulation in the putamen evoked tachypnoe, but no remarkable change in BP and HR. Stimulation in the caudate nucleus produced either tachypnoe or respiratory arrest accompanied by a slight change in BP and HR. Stimulation within the medial dorsal nucleus of the thalamus and the substantia nigra caused increase in BP, HR, and RR of different magnitude. The increase in BP failed to appear under the effect of α-adrenergic blockade. The effects of procaine, injected through the arterial cannula, did not interfere with the electrically elicited responses. All the cardiorespiratory responses to basal ganglia stimulation diminished or did not appear in deeply anaesthetised animals. We conclude that besides its involvement in motor processing, the basal ganglia circuitry exerts an influence on the central cardiorespiratory mechanisms.

自然環境下における無拘束ネコの脳単一ニューロン活動の計測と解析

自然環境下における無拘束ネコの脳単一ニューロン活動の計測と解析

Facial input to neck motoneurons: trigemino-cervical reflexes in the conscious and anaesthetised cat.

Cutaneous facial inputs influencing head movement were examined in the conscious and anaesthetised cat. EMG recordings were made in neck muscles of conscious, unrestrained cats in which an unexpected light cutaneous stimulus was applied to the glabrous skin of the planum nasale (PN). These observations established that head aversion movements were associated with synchronised activation of both deep and superficial dorsal neck muscles. In anaesthetised cats in which activity in the motoneurons of the large dorsal neck muscles was examined, mechanical stimulation of the PN or electrical stimulation of the infraorbital nerve (ION) produced a short latency, reflex activation. The reflex could be elicited by excitation of low threshold, rapidly conducting fibres in the ION. Intracellular recording from neck motoneurons showed that there is a short latency, probably disynaptic, excitatory pathway from low threshold nerves in the ION to neck motoneurons, but discharge of neck motoneurons occurred several milliseconds later, presumably as a result of activity in a longer multisynaptic pathway.

Effects of acute sleep deprivation on control of the diaphragm during REM sleep in cats.

Recently, investigators demonstrated that acute sleep deprivation in healthy subjects results in significant periodic decrements in ventilation during recovery rapid-eye-movement (REM) sleep. The neural bases of such phenomena are unknown. The decrements in ventilation coincide with REM sleep-associated phasic activities, such as bursts of eye movements. The purpose of this study was to determine the effects of acute sleep deprivation on control of diaphragm activity during recovery REM sleep. In chronically implanted, naturally sleeping, unrestrained cats, we recorded the electroencephalogram, electrooculogram, pontogeniculooccipital waves, neck and diaphragmatic electromyograms, and the computed moving average of the diaphragm. Acute sleep deprivation resulted in an increase in REM sleep-associated phasic alterations in diaphragmatic control during recovery REM sleep. There was an increase in the percentage of bursts during recovery REM sleep with reduced inspiratory drive. Acute sleep deprivation resulted in a substantial increase in the number of brief pauses (fractionations) in diaphragmatic activity during recovery REM sleep. Respiratory timing was also affected by sleep deprivation, with a reduced expiratory time resulting in an increased duty cycle ratio. There was a significant increase in the percentage of bursts with decremented peak amplitude of the moving average of the diaphragm, a measure that correlates with tidal volume. Despite significant increases in respiratory-related phasic alterations, there were no parallel increases in excitatory phenomena, i.e., eye movements or pontogeniculooccipital waves. These results imply that respiratory control mechanisms in REM sleep are sensitive to the effects of prior sleep deprivation.

Changes in the discharge patterns of cat motor cortex neurones during unexpected perturbations of on‐going locomotion.

1. The impulse activity of single neurones in the forelimb part of the motor cortex was recorded extracellularly in unrestrained cats during self-paced locomotion on a horizontal circular ladder. 2. Fifty-one cells (forty-nine of which discharged rhythmically in time with the step cycle) were recorded during encounters with a number of rungs that could be locked firmly in position or, alternatively, held in position by weak springs so that when stepped on they unexpectedly descended (under the weight of the animal) from 1 to 5 cm before contacting a mechanical stop. 3. In eleven cells (22%) including four fast-axon pyramidal tract neurones (PTNs), an increase in discharge occurred when the contralateral forelimb descended unexpectedly. Onset latency relative to the start of rung movement ranged from ca 20 to ca 100 ms. In eight cells latency was such that most of the response preceded contact of the rung with the stop; averaged over a number of trials the altered discharge in five of these cells (including two PTNs) represented an accurate profile of the averaged velocity of rung (and foot) descent. The three remaining cells appeared to be responding largely to the cessation of rung movement. 4. Thirty-six of the cells were also studied during unexpected descent of the ipsilateral forelimb and six (17%) displayed an increase in discharge (onset latency ca 35 to ca 80 ms); three of these were among those that also responded to contralateral descents. 5. These findings for skilled locomotion requiring a high degree of visuomotor coordination are discussed and it is concluded that the motor cortex is rapidly informed regarding unexpected perturbations delivered to the contralateral forelimb at the onset of stance and that changes are evoked in the pattern of impulse traffic descending via the pyramidal tract.

A technique for recording the activity of brain-stem neurones in awake, unrestrained cats using microwires and an implantable micromanipulator

A new technique is described which is suitable for long-term recording of the activity of neurones in the brain of an awake, unrestrained cat. By using telescopic electrodes, neurones up to 39 mm from the cranial surface can be reached with a miniature micromanipulator which is small enough to be left in place between recording sessions. The most stable recordings have been obtained with electrodes made from microwire, with which units have been held for up to 8 h.

Multiple observations on a single unrestrained cat of long-lasting facilitation of transmission through the lateral geniculate nucleus

The field potential responses of the lateral geniculate nucleus (LGN) to test electrical stimuli delivered to the optic tract (OT) were recorded in an unanaesthetised, freely moving cat. The response consisted of two waves, one attributable to depolarisation of the OT terminals (t), and one attributable to the postsynaptic response (r) of LGN neurones. A train of 300 electrical stimuli at 0.2 Hz to the OT alone did not influence the amplitude of these waveforms. In contrast after a train of 150 pulses had been delivered to both the OT (at 0.2 Hz) and LGN (pseudo-random with mean intervals of 0.2 Hz), the amplitude of both the t and r waves to test OT electrical stimuli was markedly enhanced for the following 6 days. Enhancement of the t wave followed that of the r wave.

Heart rate dynamics after acute cocaine administration.

We examined heart rate (HR) patterns after a bolus intravenous (i.v.) administration of a high (10 mg/kg) dose of cocaine in unrestrained cats. Mean R-R intervals, SD, and other measures of variability were assessed in three periods: waking baseline, early postcocaine administration, and later recovery periods. Cocaine resulted in initial tachycardia and reduced HR variability. This reduction in variability was independent of changes in the average rate: during the recovery period, HR returned to baseline values, but the reduced variability persisted. Nonlinear methods of assessment yielded additional results: Cocaine introduces a high correlation between one beat and the next and a tendency for cardiac accelerations to be followed immediately by decelerations and vice versa. The overall effect of the drug is to restrict deviation from a fixed rate.

Electromyographic studies of neck muscles in the intact cat. I. Patterns of recruitment underlying posture and movement during natural behaviors.

Natural head movements in alert, unrestrained cats were studied using video-filming, videofluoroscopy and electromyographic (EMG) recording methods. In each cat, up to sixteen neck muscles or neck-muscle compartments were implanted with recording electrodes. Patterns of muscle recruitment were examined during systematically-selected behavioral epochs in which the cat held a range of stationary postures, and when it performed volitional and exploratory behaviors such as flexion-extension or turning, grooming, eating, or headshaking. Patterns of muscular activity were interpreted with reference to simultaneous video images of head and neck movements. In separate, videofluoroscopic analysis, flexion-extension movements were examined to gain insight into the underlying movements of the skull and cervical vertebrae. These and other movements were found commonly to depend upon changes in joint angles between lower as well as upper cervical joints. Stationary postures in which the neck was held vertically were consistently associated with tonic EMG activity in only two long dorsal muscles, biventer cervicis and occipitoscapularis. Less consistent activity was also present in dorsal intervertebral muscles crossing lower cervical joints. When the neck was held horizontally, the long dorsal muscles increased their EMG activity and moderate activity was also recorded in deeper intervertebral and suboccipital muscles. When flexion-extension occurred around upper cervical joints, greatest activity was recorded in rectus capitis posterior and complexus, but when it involved the lower cervical joints, large changes in EMG activity could also be detected in biventer cervicis, occipitoscapularis, and the intervertebral muscles crossing lower cervical joints. During specialized, sagittal-plane movements such as grooming, well-defined patterns of synergy could be recognized that varied according to the degree of involvement of upper and lower cervical joint-sets. Movements in the horizontal plane were associated with EMG activity in a largely different subset of neck muscles including splenius, longissimus capitis and obliquus capitis inferior. The levels of EMG activity during flexion-extension or turning movements were much lower than those observed during other more vigorous behaviors, such as head shaking. Some neck muscles, such as clavotrapezius and sternomastoideus, could only be recruited during forceful or ballistic head movements. Results showed that the patterns of muscular activation were linked not only to the speed and trajectory of the movements of the skull, but also to the kinematics of the motion occurring across different parts of the cervical column.

Substantia nigra stimulation and blood pressure effects of locally applied kainic acid

Cardiovascular response to electrical stimulation of the substantia nigra were studied in awake, unrestrained cats. Significant increases in the arterial blood pressure, heart rate and respiratory rate appeared simultaneously with the somatomotor effects of stimulation. Twenty-four hours after local microinjection of kainic acid into the site of stimulation the blood pressure responses to stimulation were reduced by 70%, while the changes in heart rate and respiratory rate effects were not statistically significant. Intense somatomotor effects appeared about 30 min after the injection. However, the animal recovered much of its behavioural functions within five hours. It is concluded that the substantia nigra, besides its somatomotor functions, has a role in regulation of blood pressure.

Changes in motor performance and rubral single unit activity in cats after microinjections of serotonin into the red nucleus area

The serotonergic control exerted on the red nucleus (RN) was studied in unrestrained cats during the performance of a simple reaction time task which consisted of releasing a lever in response to an auditory go-signal. The effects of microinjections of serotonin-oxalate salt into the rubral area on the motor activity and on the firing of neurons recorded concomitantly in the red nucleus were investigated. Injections of serotonin (5-HT) (200–400 ng) into the red nucleus or its dorsal border induced subtle alterations in the conditioned motor performances but had no major effects on the spontaneous motor behavior. The changes in the conditioned motor output (an increase in the static force exerted on the lever and a speeding up of the lever release) are reminiscent of the facilitatory influence of serotonin on various motor reflexes previously reported. Changes in the neuronal activity were observed concomitantly with the effects on the motor output: 5-HT either enhanced or reduced the firing rate of the rubral neurons. These effects were apparently dependent on the discharge pattern of the neurons during the static motor activity. The results suggest that the serotonergic input to the red nucleus may participate in motor control by exerting a dual modulatory action on the activity of rubral neurons.

Dynamic properties of respiratory timing following cocaine administration

We assessed the timing and amplitude characteristics of diaphragmatic muscle activity following administration of intravenous cocaine HCl (10 mg/kg) to awake, unrestrained cats. Cocaine produced a pronounced tachypnea which was interrupted by deep inspiratory efforts coincident with tonic-clonic movements over the first 10 min following cocaine administration. Following that period, diaphragmatic cycle rates slowly increased for up to 1 h and were interrupted occasionally by longer inspiratory efforts which were not associated with other overt motor activities. As respiratory rate increased, breath-to-breath variability decreased, and the incidence of deep inspiratory efforts decreased. As total cycle time decreased, the ratio of inspiratory time to expiratory time remained the same between precocaine and early, intermediate and late intoxication periods. The amplitude of diaphragmatic EMG activity increased with the extreme tachypnea. A number of neural mechanisms may mediate the changes in diaphragmatic muscle activity, including hyperthermia and alteration of rostral brain influences on brainstem timing mechanisms.

A technique for recording from brain-stem neurones in awake, unrestrained cats

A method is described which enables single unit recordings to be made from neurones over a wide area of the brain-stem of awake, unrestrained cats. A small headpiece, made from titanium and acrylic, was fixed to the skull over a craniotomy at pre-set stereotaxic co-ordinates. Between recording sessions the craniotomy was sealed. During recording, a miniature micro-manipulator and adjustable titanium support was screwed into the headpiece and recordings were made with tungsten electrodes.

Functionally complex muscles of the cat hindlimb

The cat sartorius (SA) can be divided functionally into an anterior (SAa), knee extensor portion and a medial (SAm), knee flexor portion; it can be further subdivided anatomically by multiple nerve branches into parallel longitudinal columns that terminate in a distributed insertion at the knee with a continuous range of moment arms. Thus, SA may be controlled by a discrete number of motoneuron task groups reflecting a small number of central command signals or by a continuum of activation patterns associated with a continuum of moment arms. To resolve this question, the activation patterns across the width of the SA were recorded with an electrode array during three kinematically different movements--treadmill locomotion, scratching and paw shaking, in awake, unrestrained cats. Uniformity of activation along the longitudinal axis was also examined because individual muscle fibers do not extend the length of the SA. In addition, the cutaneous reflex responses were recorded throughout all regions of the SA during locomotion. Two fascial surface-patch arrays, each carrying 4-8 pairs of bipolar EMG electrodes, were sutured to the inner surface of the SA, one placed proximally and the other more distally. Each array sampled separate sites across the anterior to medial axis of SA. During locomotion, two basic EMG patterns were observed: the two burst-per-step-cycle pattern typical of SAa and the single burst pattern typical of SAm. There was an abrupt transition in the pattern of activation recorded in the two parts of SA during locomotion, and no continuum in the activation pattern was observed. Stimulation of both sural and saphenous cutaneous nerves during locomotion produced reflex responses that were uniformly distributed throughout SA, in contrast to the regional differences noted during unperturbed walking. Similarly, during scratching and paw shaking all parts of the SA were active simultaneously but with regional differences in EMG amplitude. The abrupt functional border between SAa and SAm coincided with the division of the SA into a knee flexor vs. a knee extensor. In all cases, the quantitative and qualitative differences in SAa and SAm EMGs were uniformly recorded throughout the entire extent of SAa or SAm; i.e., there was no segregation of activity within either SAa or SAm. Furthermore, the time course of EMG from each proximal recording site was nearly identical to the corresponding distal site, indicating no segregation of function along the longitudinal axis of SA. These results indicate that SAa and SAm constitute the smallest functional modules that can be recruited in SA.(ABSTRACT TRUNCATED AT 400 WORDS)

Methods for recording the jaw-opening reflex to tooth-pulp stimulation in awake cats

Techniques are described for use in awake, unrestrained cats which enable recordings to be made from the digastric muscle, electrical stimuli to be applied to the teeth, and intravenous injections to be made via an indwelling cannula. A headpiece was fixed to the skull of the animal and leads were passed subcutaneously from it to electrodes in the muscle and the teeth. A silicone rubber cannula was inserted into the external jugular vein and connected to an injection port in the headpiece. The headpiece incorporated a miniature 9-way connector which was connected to the electrode leads.

Segmental reflex action in normal and decerebrate cats

1. The objective of this study was to evaluate the action of the stretch reflex on the ankle extensor muscles of normal and decerebrate cats. 2. Experiments were performed on nine freely standing, unrestrained cats and repeated after decerebration at the premammillary level. The length, force, and electromyograph (EMG) of the soleus (SOL) and lateral gastrocnemius (LG) muscles were recorded with the use of implanted transducers and electrodes. 3. The left ankle joint was unexpectedly and reproducibly dorsiflexed by briefly stimulating the common peroneal (CP) nerve with electrodes within an implanted nerve cuff. The ensuing twitch contractions of the ankle dorsiflexor muscles stretched the ankle extensor muscles by 0.3-2.0 mm. Lidocaine was infused into another nerve cuff proximal to the stimulation site, to reversibly block the central propagation of evoked volleys in the CP nerve. 4. Reflex action before and after decerebration was measured from the responses to perturbations of similar amplitude and duration delivered at approximately matched background values of muscle length and force. In most cats the temperature of the hindlimb was monitored with an implanted thermistor and was restored to normal values with radiant heat after decerebration. 5. A stretch imposed on the tonically active ankle extensor muscles immediately caused a considerable rise in the force recorded from the triceps tendon. Within 30-40 ms the triceps force peaked, reaching a value 10-20 N greater than background, and then rapidly declined while the extensor muscles were still lengthening. The initial rise in force preceded any change in triceps EMG. It was attributed to the intrinsic viscoelasticity of the stretched muscles and tendons. After decerebration the magnitude and timing of the initial force peak did not change. 6. A short-latency reflex EMG burst was typically recorded from both the SOL and LG muscles, starting 11-17 ms after stimulus onset. After decerebration the area of the reflex EMG burst increased in all nine cats, typically by a factor of 2 or 3. 7. After decerebration a second, smaller increase in force was typically observed starting 60-80 ms after onset of stretch. This later force rise, interpreted to be of reflex origin, was rarely apparent in normal cats. 8. Decerebration introduced consistent modifications in postural behavior that were revealed by pushing down on the back of quietly standing cats. In normal cats, after brief pushes that stretched the ankle extensor muscles by 1-2 mm, the EMG, force, and length quickly stabilized near their initial values.(ABSTRACT TRUNCATED AT 400 WORDS)

Perception of complex signals by unrestrained cats

The ability of cats to discriminate modulation parameters of linearly amplitude- and frequency-modulated signals was investigated under conditions of free behavior of the animals. The maximum variations of the amplitude and frequency of the modulated signals for which the probability of discrimination is equal to the threshold (0.75) are 1.6 dB and 150 Hz for a carrier frequency of 2.5 kHz. Replacement of one type of modulation by the other in those cases when stimuli with supraliminal values of the modulation parameters (15 dB and 1 kHz) leads to random selection during discrimination of these signals by the animals. In the case of an analogous replacement of the type of modulation for signals with threshold values of the modulation parameters, the probability of discrimination becomes significant (p greater than 0.05).

Long term recordings in the cat motor cortex: unit activity and field potentials from sensory and brain stem stimulation as a means of identifying electrode position

A method of chronically implanting microwires (25 μm diameter, 90% Pt/10% Ir wire) in the cat pericruciate cortex is described. These wires can obtain simultaneous recordings of single and multiunit activity from different sites and multiple recordings from the same site on different postoperative days. The electrodes were permanently implanted in the anaesthetized animal and left in place. Recordings were carried out in the awake, unrestrained cat. Different units were recorded as a result of spontaneous electrode movement in the cortex. Movement was documented with field potential recording from the implanted electrodes and resulted in changes in the latency and polarity of the initial components of the cutaneous field potential and changes in the number of components of the field potential elicited from brain stem stimulation. Changes in the receptive fields of the units, changes in the number of units antidromically invaded from brain stem stimulation, and in the threshold and occurrence of muscle activity elicited from intracortical microstimulation supported the evidence of electrode movement obtained from field potential recordings and could be used to document electrode movements tangential to the plane of the cortical laminae. Movement was a slow gradual process throughout the period of implantation. The longest period from which a single unit could be recorded was 2 days. The need for this neurophysiological analysis is supported by evidence for irregular electrode movement which could not have been reconstructed from histological examination of the cortex.

EMG activities of neck muscles underlying lateral flexion of the neck during head-turning induced by electrical stimulation of the caudate nucleus in cats.

Patterns of EMG activities of neck muscles underlying the initiation of head-turning, induced by stimulation of the caudate nucleus, were analyzed with special reference to temporal relations between the onset of head-turning and that of changes in EMG activities. These patterns were compared with those associated with the initiation of lateral flexion of the neck which occurred without electrical stimulation of the caudate nucleus in order to examine whether the caudate-induced head-turning was initiated via the same muscular system as that used in non-caudate-induced head movements. Experiments were carried out using 5 awake, unrestrained cats which were trained to stand still with one limb on each of 4 footplates. Trains of stimulating current pulses were applied to several stimulation points in the caudate nucleus while the animal maintained a stable standing posture with its neck extended. Head movements in the horizontal plane and EMGs of 6 neck muscles (splenius, longissimus cervicis, obliquus capitis caudalis, biventer cervicis, complexus and cervical multifidus) were recorded. Patterns of EMG activities of neck muscles around the onset of the caudate-induced head-turning were characterized by an increase in activity of the splenius, the longissimus cervicis and the obliquus capitis caudalis muscles, and by a decrease in activity of the complexus, the biventer cervicis and the cervical multifidus on the side of flexion. It is suggested that an increase in activity of the splenius, the longissimus cervicis and the obliques capitis caudalis muscles was responsible for the initiation of this evoked response. In non-caudate-induced lateral flexion of the neck, patterns of activities of neck muscles were similar to those in caudate-induced head-turning. It is therefore concluded that the caudate-induced head-turning as an evoked behavioral response was initiated through a muscular system similar to that utilized for similar head movements occurring without electrical stimulation of the caudate nucleus, although the pathways involved are thought to be different.

Pikamilon-a new vasoactive and nootropic preparation

It has therefore been suggested that a combination of nicotinic acid and GABA in the same molecule would potentiate the action of each component. Compound nicotinoyl-~-aminobutyric acid was first synthesized at the All-Union Vitamin Research Institute in 1970 [ii], and in the subsequent years the product pikamilon, created on its basis, has been widely studied both experimentally and clinically. Pikamilon, a sodium salt of N-nicotinoyl-~-a minobutyric acid, is a white crystalline odorless and hygroscopic powder, readily soluble in water. It was shown when the research had only begun that the compound passes rapidly through the BBB. The essential role of GABA in the central and peripheral regulation of the cerebral circulation [4, 14, 15, 17] and also the presence of a nicotinic acid residue possessing vasoactive properties, determined the priority given to the study of the cerebrovascular properties of pikamilon. In experiments on animals pikamilon had a positive action on the cerebral circulation and also exhibited the properties of a tranquilizer with stimulating component [7]. The action of the compound on the cerebral circulation and on its nervous regulation was studied in experiments on anesthetized cats, on conscious, unrestrained cats, and on unanesthetized rabbits. Pikamilon was shown to stimulate the cerebral circulation and to lower vascular tone in both arterial systems of the brain. The increase in the blood supply to the brain in conscious animals took place to a more marked degree than in cats under general anesthesia. The drug also lowered the blood pressure. It must be emphasized that these effects were manifested after both intravenous and peroral administration of the compound. In anesthetized cats, pikamilon in a dose of i0 mg/kg, given by intravenous injection, increased the blood flow by 28  3%, but when given internally -- by 18  1.7%; in conscious animals it was increased by 63  10% and the effect lasted 120-150 min. The increase in the blood flow in unanesthetized rabbits was 42  7.3% by Intravenous injection and 24  8% by the peroral route. In the strength and duration of its cerebrovascular effect, pikamilon is much superior both to GABA and to nicotinic acid. Under the same experimental conditions GABA in a dose of i0 mg/kg (intravenously) caused no change in the cerebral bloodflow, and only when given in a dose of 300 mg/kg did it increase the blood flow into the brain by 20  2.9%, the effect lasting 3-5 min. Nicotinic acid, also in large doses (50-100 mg/kg) increased the cerebral blood flow temporally on average by 5-10%. In its effect on the cerebral circulation, in comparative experiments pikamilon was more effective than papaverine, nialamide, complamin (xantinol nicotinate), and dihydroergotoxin (redergin). An essential role in the mechanism of action Of pikamilon is played by its effect on nervous control of the cerebral circulation. It weakens changes in the cerebral blood flow during the vasomotor reflex, considerably inhibits constrictor responses of vessels of the