Correlation of unit activity of the right and left amygdala in food motivation and emotional stress

Correlation between activities of neurons in the right and left central nuclei of amygdala of rabbits recorded during quiet wakefulness, after 24-h food deprivation, after satiation and during emotional stress (demonstration of a dog) was studied by plotting crosscorrelation histograms. The histogram peaks shifted from zero were observed in 50-67% cases. In hungry animals, in a greater number of cases (52%), the discharge of a neuron in the left amygdala was the first in a pair, and the discharge of the right neuron was delayed (peaks from 10 to 50 and from 130 to 150 ms). The opposite order of discharges was less frequent (36%). When a rabbit saw a dog, the number of common inputs to neurons increased and the leading role of the right amygdalar neurons grew (57%) due to an increase in inhibitory influences from the right to the left amygdala. In most cases, the interaction between amygdalar neurons occurred at the frequencies of the delta range, predominantly, from 2 to 4 Hz.     

电刺激蝙蝠中脑上丘对下丘听神经元电活动的影响

实验在24只鲁氏菊头蝠(Rhinolophus rouxi)上进行.使用玻璃微电极在中脑下丘中央核记录听神经元电反应.刺激点位于上丘核.共观察了294个对超声刺激产生反应的下丘听单位.当电刺激上丘时,有122个听单位的反应受到影响,占所观察总数的41.5%.其中96个单位表现为抑制性影响(占32.65%),26个单位表现为易代性效应(占8.84%).其余172个单位不受上丘刺激的影响(58.50%).实验中发现,上述抑制潜伏期一般在5毫秒以上,抑制时程较长.抑制程度与上丘刺激电流强度呈相关关系(r=0.99).实验中还发现,刺激上丘同样可抑制部分下丘神经元的自发放电活动,其抑制后效应相当长,有的可达120毫秒以上.     

The effect of high-frequency stimulation of the midbrain reticular formation on the interaction of neocortical neurons]

The influence was studied of midbrain reticular formation (NRT) stimulation at the rate of 75-100 Hz by the current of 33-400 mkA upon the neuronal interaction in the visual and somatosensory regions of rabbits neocortex. Histograms of cross- and autocorrelation of impulse trains were plotted. NRT stimulation resulted (as compared with calm wakefulness) in an increase of the number of pairs of neurons with correlated activity and in an increase of the probability of neurons discharges 100-400 ms one after another. Mechanisms of cellular interaction did not change. Comparison with the previously obtained data allowed to conclude that NRT activation can induce certain changes in neuronal interaction observed during pseudoconditioning and early phases of conditioning.     

Neuronal impulse trains of the visual and sensorimotor areas of the rabbit neocortex in calm wakefulness and pseudoconditioning

The conjugation of unit activity in the neocortical visual and sensorimotor areas during calm wakefulness and in intersignal intervals, in two groups of rabbits at pseudoconditioning was studied. The first group was presented in a random order with flashes and electrocutaneous stimuli, the second one--with sounds and electrocutaneous stimuli. The number of neurones pairs working in correlation during calm wakefulness is significantly less (35%) than during pseudoconditioning (49 and 50% in the first and second rabbits groups, respectively). During calm wakefulness and in both groups during pseudoconditioning, the number of pairs with delays of discharges of the visual area neurones after the sensorimotor one, and of the sensorimotor after visual up to 120 ms was equal. Comparison of the data on delayed neuronal discharges during calm wakefulness and pseudoconditioning with those obtained earlier with conditioned reflexes testifies that forestalling of visual area neuronal discharges by sensorimotor discharges is characteristic only for the activity of cortical projections of conditioned and unconditioned stimuli.     

Action of calcitonin gene-related peptide (CGRP) and substance P on neurons in the insular cortex and the modulation of taste responses in the rat

Using multibarrel electrodes, recordings were made from single neurons in the insular cortex including the cortical taste area (CTA) of urethane-anesthetized rats. The effects of an iontophoretic application of calcitonin gene-related peptide (CGRP) and substance P (SP) on the spontaneous discharges and taste responses were tested. In a total sample of neurons (mostly non-taste), CGRP affected the spontaneous discharges in 35.6% of the 571 neurons studied and SP in 38.3% of the 775 neurons studied. The effects were mostly (approximately 85-87%) facilitatory. Peptide-sensitive neurons were found at a similar frequency in all three insular areas-granular, dysgranular and agranular (areas GI, DI and AI). This is in contrast to previous reports that CGRP receptors were rich in area DI and CGRP-immunoreactive afferents numerous in area AI, but consistent with previous reports that the distribution of SP receptors and SP fibers was dense in the insular cortex. In approximately 40% of the 76 taste neurons recorded from areas GI and DI, the peptides affected the spontaneous discharges (mostly facilitated). When the taste responses were examined during application of the peptides, significant (mainly depressant) effects were seen in 61% of 18 neurons for CGRP and in 70.5% of 17 for SP. Such effects were not recognized on responses to specific taste stimuli and were not correlated with the effects on the spontaneous discharges. The findings indicate that both peptides modify taste coding in CTA neurons presynaptically and/or postsynaptically, independently of the existence of receptors on the neurons.     

Patterns of early and late discharges in somatotopically identified precentral neurons in awake monkeys in response to somatic inputs.

Extracellular recordings were made of single neurons in precentral cortex of awake monkeys. These neurons were somatotopically identified with respect to their responses to inputs from single joints or their somatic surround. Many of these neurons exhibited early (less than 50 ms) and late (greater than 50 ms) discharges in response to flexion or extension torques delivered about the wrist. With the monkey in a mode requiring opposition to the injected torque, all responsive neurons showed a parallel excitatory or inhibitory modification in the early and late discharges. This was true both for cells identified as wrist (flexion-extension) neurons and those identified as nonwrist (flexion-extension) neurons. These findings indicate that the reflex and voluntary components of percentral discharge invariably show a congruent functional response to a torque disturbance, for this particular instruction set.     

Activity of lumbar interneurons during late long-lasting discharges in motor nerves of immobilized thalamic cats

Activity of lumbar spinal neurons was recorded extracellularly during late long-lasting discharges in efferent nerves in immobilized thalamic cats. Of the total number of cells tested, 70% changed their activity during late discharges. The activity of 35% of neurons was increased during late discharges in nerves to flexors, but inhibited during discharges in nerves to extensors. Responses of 27% of neurons were of the opposite character. Other neurons were found whose activity was increased (5%) and reduced (3%), respectively, during later discharges in both flexor and extensor nerves. Most interneurons which changed their activity during late discharges were located in lateral parts of the intermediate zone of gray matter and the ventral horn at a depth of 2.8 mm. The character of the afferent input to a neuron was found to depend on the late efferent discharges and activity of the neurons correlated with them. Neurons whose activity was unchanged during late discharges (30%) were mainly located rather more dorsally, at a depth of about 2.0 mm. The possible mechanisms of the participation of these groups of interneurons in the generation of late discharges are discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 11, No. 3, pp. 236–244, May–June, 1979.     

Interhemispheric asymmetry of neocortex and hippocampus in orienting exploratory behavior of rabbits

Correlation of discharges of cortical neurons in symmetrical points of the visual and parietal cortices and left and right hippocampal CA1 neurons was studied in freely moving rabbits during exposure to emotional stimuli. Crosscorrelation histograms were plotted. As compared to the initial state, during an active orienting exploratory reaction to stimuli, the left-side influence on right-hemispheric cortical neurons with a delay about 100 ms increased, which led to asymmetry in interhemispheric interaction with the left-side dominance. During freezing, the left-side influence became weaker, and the effects of the right hemisphere prevailed. Hippocampal asymmetry in neuronal activity was in reciprocal relationship with neocortical asymmetry. In the hippocampus, the right-side influence with a delay about 200 ms increased during the active exploratory reactions resulting in the right-side dominance. Freezing was accompanied by strengthening of the left-side influence (the left-side dominance). During the active locomotion, neuronal interaction in the hippocampus was predominantly realized in the theta-range frequency, whereas freezing was characterized by the delta-range correlation. It was concluded that the active or passive nature of a behavioral reaction to emotional stimuli was correlated with changes in asymmetry in the interhemispheric neuronal interactions at the cortical and hippocampal levels.     

Correlated activity of neurons in the sensorimotor cortex of rabbits in the state of defensive dominanta and "animal hypnosis"

A hidden excitation focus (dominanta focus) was produced in the rabbit's CNS by threshold electrical stimulation of the left forelimb with the frequency of 0.5 Hz. As a rule, after the formation of the focus, pairs of neurons with prevailing two-second rhythm in their correlated activity were revealed both in the left and right sensorimotor cortices (with equal probabilities 29.3 and 32.4%, respectively). After "animal hypnosis" induction, the total percent of neuronal pairs with the prevalent dominanta-induced rhythm decreased significantly only in the right hemisphere (21%). After the termination of the "animal hypnosis" state, percent of neuronal pairs in the right cortex with prevailing two-second rhythm significantly increasead if the neurons in a pair were neighboring and decreased if they were remote from each other. Similar changes after the hypnotization were not found in the left cortex. Analysis of correlated activity of neuronal pairs with regard to amplitude characteristics showed that for both the right and left hemispheres, the prevalence of the two-second rhythm was more frequently observed in crosscorrelation histograms constructed regarding discharges of neurons with the lowest spike amplitude (in the right hemisphere) or the lowest and mean amplitudes (in the left hemisphere) selected from multiunit records.     

猫体感皮层神经元对同时刺激隐神经的A类和C类纤维的反应型式

记录了麻痹猫的体感皮层(SI)神经元的自发和隐神经的A类和C类纤维传入诱发放电(A-ED和C-ED)。用NCCVF分析神经元放电。结果表明,SI区神经元对同时刺激隐神经的A类和C类纤维的反应呈多种型式:(1)A-ED和C-ED共存,包括Ⅰ.A-ED和C-ED始终相互伴随出现;Ⅱ.在刺激之初,只出现A-ED,但是,当阻断A类纤维传入并由C类纤维传入诱发神经元放电后,再同时刺激A类和C类纤维时,A-ED和C-ED便同时出现。(2)A-ED制约C-ED,特点是,只要A-ED存在,C/ED就不出现。只有阻断A类纤维传入后,C-ED才产生。(3)单一A-ED,不管在什么刺激条件下,这类神经元都只有A-ED,而不产生C-ED 结论:根据反应型式的不同,可将SI区的神经元分为Ⅰ.A类和C类纤维传入同时驱动的神经元;Ⅱ.A-ED制约C-ED的神经元;Ⅲ.只由A类纤维传入驱动的神经元。     

Mauration of unitary responses to tonal stimulation in the cochlear nerve of the kitten]

The maturation of single auditory nerve fiber responses to long-duration (500 ms) tone-bursts was studied in kittens at various stages after birth. Spike discharges were examined as a function of three criteria. 10 Latency. Mean value of the "on" peak latency was about 25 ms at 1 to 3 days after birth. It then regressed, reaching 8 to 12 ms at the end of the first week, and 2 to 4 ms at 20 days. 20 Peristimulus histograms (PSTH). Evolution of PSTH revealed the characteristic sequence of unit reactivity to long duration stimuli (i.e. on, rhythmic, and continuous responses). Rhythmic responses is assumed up to now to be related to the immaturity of synaptic junctions below the hair cells. 30 interval histograms. The interspike interval histograms of the discharges showed a similar evolution. A bimodal distribution corresponding to the rhythmic mode of reactivity, appeared at the end of the first week.     

Effect of pentobarbital on unit activity of reticular and ventrolateral thalamic nuclei in cats

Responses of single units in the reticular and ventrolateral thalamic nuclei were studied in acute experiments on curarized cats before and after intravenous injection of small doses (0.5–15 mg/kg) of pentobarbital, with simultaneous derivation of activity by two electrodes. After injection of pentobarbital, unit activity in the reticular nucleus consisted of high-frequency grouped (52.5% of 40 neurons) or continuous (30%) discharges as long as barbiturate spindles were present in the electrocorticogram. Activity of only four neurons (10%) of this nucleus was inhibited during the presence of spindles. In all other neurons of the reticular nucleus (7.5%) the character of discharges was unchanged after injection of pentobarbital. The appearance of grouped discharges, repeated several times (66.5% of 40 neurons), or blocking of activity (30%) throughout the period of spindle recording was observed in neurons of the ventrolateral nucleus. The remaining neurons of that nucleus (3.5%) did not respond to intravenous pentobarbital. The appearance of high-frequency discharges in neurons of the reticular nucleus while spindles were recorded coincided with a period of silence in neurons of the ventrolateral nucleus (58.5% of 34 pairs of neurons). High-frequency electrical stimulation of the mesencephalic reticular formation led to asynchronous activation of neurons of the ventrolateral nucleus (82%) and inhibition of unit activity in the reticular nucleus (88%).I. S. Beritashvili Institute of Physiology, Academy of Sciences of the Georgian SSR, Tbilisi. Translated from Neirofiziologiya, Vol. 14, No. 5, pp. 517–524, September–October, 1982.     

Dependence of behavioral responses form during shake-off conditional reflex on laterality of the neocortex

Pattern of discharges and interhemispheric interaction of parietal neurons (somatosensory presentation of the ear) were compared in interstimulus intervals before active shake-off and passive freezing reactions at stimuli after elaboration defensive avoid reflex. Before passive reactions in contrast to active right-side influences on left-side neurons were reinforced with delay to 100 ms, it result in appearence of asymmetry in interhemispheric interaction with right-side dominance. Before passive reactions intensity of delta-frequencies was increased in impulsation of single neurons and in interaction of cells pair. On this evidence the pattern of interhemispheric asymmetry before stimuli can be one of a number of factors, determinant active or passive form of behavioral reactions and also reflective of activation level of neocortex.     

Sound duration and sound pattern affect the recovery cycles of inferior collicular neurons in leaf-nosed bat, Hipposideros armiger

The effects of sound duration and sound pattern on the recovery cycles of inferior collicular (IC) neurons in constant frequency-frequency modulation (CF-FM) bats were explored in this study. Five leaf-nosed bats, Hipposideros armiger (4 males, 1 female, 43-50 g body weight), were used as subjects. The extracellular responses of IC neurons to paired sound stimuli with different duration and patterns were recorded, and the recovery was counted as the ratio of the second response to the first response. Totally, 169 sound-sensitive IC neurons were recorded in the experiment. According to the interpulse interval (IPI) of paired sounds when neurons reached 50% recovery (50% IPI), the recovery cycles of these IC neurons were classified into 3 types: fast recovery (F, the 50% IPI was less than 15 ms), short recovery (S, the 50% IPI was between 15.1 and 30 ms) and long recovery (L, the 50% IPI was more than 30 ms). When paired CF stimuli with 2 ms duration was used, the ratio of F neurons was 32.3%, and it decreased to 18.1% and 18.2% respectively when 5 and 7 ms CF stimuli were used. The ratios of S and L neurons were 41.5%, 33.7%, 29.1% and 26.2%, 48.2%, 52.7% respectively when 2, 5 and 7 ms CF stimuli were used. The average 50% IPI determined after stimulation with paired 2 ms, 5 ms and 7 ms CF sounds were (30.2 ± 27.6), (39.9 ± 29.1) and (49.4 ± 34.7) ms, respectively, and the difference among them was significant (P< 0.01). When the stimuli of paired 2 ms CF sounds were shifted to paired 2 ms FM sounds, the proportion of F, S and L neurons changed from 32.3%, 41.5%, 26.2% to 47.7%, 24.6%, 27.7%, respectively, and the average 50% IPI decreased from (30.2 ± 27.6) to (23.9 ± 19.0) ms (P< 0.05, n = 65). When paired 5+2 ms CF-FM pulses were used instead of 7 ms CF sounds, the proportion of F, S and L neurons changed from 18.2%, 29.1%, 52.7% to 29.1%, 27.3%, 43.6%, respectively, and the average 50% IPI decreased from (49.4 ± 34.7) to (36.3 ± 29.4) ms (P< 0.05, n = 55). All these results suggest that the CF and FM components in echolocation signal of CF-FM bats play different roles during bats' hunting and preying on. The FM component of CF-FM signal presenting in the terminal phase can increase the number of F type neurons and decrease the recovery cycles of IC neurons for processing high repetition echo information, which ensures the bat to analyze the target range and surface texture more accurately.     

Comparative characteristics of the neuronal activity of the anterodorsal and anteroventral nuclei in thalamus slices from guinea pigs

Extracellular investigation of neurons of the anterodorsal (AD) and anteroventral (AV) nuclei in the incubated slices of the thalamus of guinea pigs and rabbits revealed unusual properties of the AD units. They responded only to electrical stimuli of considerable duration (1-5 ms) by multispike initial bursts or by prolonged (1-15 s) high frequency phasic discharges. Summation of effects of successive stimuli following with intervals of 2-30 s was necessary for development of phasic discharges. Prolonged refractory state (up to 2-15 s) followed the discharges. They were blocked in low Ca2+, high Mg2+ medium and facilitated in a medium with high concentration of K+. The nature of unusual properties of AD neurons, not present in the neighbouring AV nucleus, are discussed.     

Impulsation of hypothalamic and amygdalar neurons in bilateral derivations in the state of food motivation

The character of impulsation of single neurons in the lateral hypothalamic and amygdalar central nucleus of rabbits recorded in bilateral derivations during quiet wakefulness, after 24-h food deprivation, and after satiation was studied by plotting autocorrelation histograms and by counting the mean frequency of discharges. During the transition from hunger to satiation, the character of impulsation of neurons in hypothalamus and amygdala changed in different ways: (1) a greater number of hypothalamic than amygdalar neurons changed their mean discharge frequency (85 versus 56%, respectively); (2) in hunger, the number of hypothalamic neurons with delta-frequency oscillations decreased as compared to quiet wakefulness and satiation, and in the amyglala the number of neurons with beta2-frequency oscillations increased; (3) in hunger, the number of hypothalamic neurons with bursting and periodic discharges decreased and the number of amygdalar neurons with equiprobabilistic discharges increased. During state alternation (according to the autocorrelation histograms) the strongest changes in the character of neuronal discharges took place in the left hypothalamus and left amygdala. The maximum differences in neuronal impulsation between the left and right hypothalamus were observed in the state of hunger and between the left and right amygdala, after satiation.     

GABA能抑制调制大棕蝠下丘听神经元时间编码模式

大棕幅（Eptesicus fuscus）下丘神经元对重复率为10pps(pulse per second）、30pps的串声刺激均产生跟随反应,但对90pps串声刺激的跟随反应则不尽相同,微电泳bicuculline阻断GABA能抑制作用后,所记录的58个神经元中,有13个（22％）放电率及串声刺激反应模式无;45个（78％）神经元放电率有不同程度的增加。对10pps、30pps串声刺激仍能产生跟随反应,但对90pps串声刺激的跟随反应模式有多种变化。其中：17个（29％）神经元为放电率增加的跟随反应;9个（15％）神经元放电率增加,对前100ms的串刺激产生反应且放电密集,而对随后200ms的串刺激只产生少量的放电;15个（26％）神经元放电率增加,在前几十毫秒范围内有较多的放电反应,后续的反应很弱;4个（7％）神经元只对第一个声刺激产生反应,且放电率增加,随后放电急剧减少。结果提示中脑下丘神经元对听觉信息的时间编码可能具有更复杂的机理。     

Limited plasticity of the rabbit visual cortex and hippocampal neurons in the oddball test

The activity of 41 visual cortex and 20 hippocampal neurons from field CA1 was registered in experiments using oddball-stimulation with different color stimuli varied in intensity. 34% cortical and 37% hippocampal neurons demonstrated plasticity reactions. The significant increase of latest phases of neuronal activity (200-500 and 200-1000 ms after stimulation for cortical neurons and 300-550 ms for hippocampal neurons) was shown in responses to rare deviant stimuli, which had a less intensity than frequently standards. The quantity of the earliest neuronal phase of activity (40-120 ms after stimulation) was stabilized in responses to deviants and standards during the experiment. We propose that such increase of the latest phases of neuronal activity (the limited plasticity) may reflect the mechanisms of orienting reaction.     

Features of the spontaneous unit activity in the human thalamic parafascicular (CM-Pf) complex and its modification in functional cerebral changes

New data on neural organization of the human thalamic parafascicular (CM-Pf) complex were revealed with microelectrode technique during 11 stereotaxic operations in alert diskinetic patients suffering from the tonic forms of spasmodic torticollis. The data were obtained as follows: the functional heterogeneity in cellular organization of the human CM-Pf thalamic nuclei and the existence of three (A, B and C) different types of neurons in these thalamic nuclei: with the irregular discharges (A-type, 18%); with short (10-20 ms) bursts characterised by unstable rhythmic 2-5 Hz pattern and by the low threshold Ca2+ dependent K+ conductance (B-type, 77%); with long-lasting (0.1-2.0 s) bursts of high-frequency trains and constant interburst intervals (C-type, 5%). The functional cerebral changes after motor test performances were shown to be accompanied by appearance of transient modifications of the background unit activity pattern and by tendency towards an increase of neural activity local synchronisation with some stabilising of oscillatory rhythm of discharging B-type neurons. For the first time, a direct relationship between functional characteristics of the human thalamic CM-Pf units and the motor deviations was found in spasmodic torticollis patients.     

The influence of the auditory cortex on acoustically evoked cerebellar responses in the CF-FM bat,Rhinolophus pearsonic chinesis

1. Acoustically evoked responses of 284 neurons isolated from the cerebellar vermis, hemispheres and paraflocculus of Rhinolophus pearsonic chinesis were studied under free field acoustic stimulation conditions. 2. The BFs of these cerebellar auditory neurons ranged from 24 to 76 kHz but they mostly fall either between 48 and 64 kHz or between 65 and 76 kHz. However, the BF distribution varies among vermal, hemispheric and parafloccular neurons. 3. Threshold curves of cerebellar neurons are generally broad but those tuned to the frequency of the predominant CF component are extremely narrow. 4. Response latencies of cerebellar neurons ranged from 2 to 48 ms suggesting multiple auditory cerebellar pathways. The latency distribution also varies among vermal, hemispheric and parafloccular neurons. 5. Although both the vermis and hemispheres contain a disproportionate number of 65-74 kHz neurons, the response latencies of those neurons isolated from the vermis are scattered over a wide range of 2.2-28 ms while those neurons isolated from the hemispheres are generally stabilized between 5 and 12 ms. 6. Electrical stimulation of the auditory cortex evokes discharges from a recorded cerebellar auditory neuron. Cortical stimulation also facilitates the response of an acoustically evoked cerebellar neuron by increasing its number of impulses. The degree of facilitation is dependent upon the amplitude of the acoustic stimulus. 7. For a given electrical and acoustic stimulation condition, the facilitative latency and the degree of facilitation varied with the interstimulus interval. Among 23 neurons studied, most of them (19 neurons, 82.6%) had a maximal facilitative latency between 2 and 10 ms. 8. By examining the difference in the facilitative effect in each isolated cerebellar auditory neuron before and after a topical application of local anesthetic, procaine, onto the point of electrical stimulation in the auditory cortex, we found that the facilitative pathways to vermal and hemispheric neurons may be different from the pathway to parafloccular neurons. 9. Possible auditory pathways to different parts of the cerebellum are discussed in relation to the wide range of recorded response latencies. 10. The facilitative influence of the auditory cortex on the cerebellar auditory neurons is assumed to enhance the cerebellar role in acoustic motor orientation.