Lateralization of opioid receptors and their putative ligands in the visual cortex of the turtle

Opioid mu-agonist morphine, delta-agonist D-Ala2,D-Leu5-enkephalin (DADL) and kappa-agonist bremazocine locally applied to the surface of turtle visual cortex inhibited the orthodromic evoked potential (EP; fast negative component N1). The lack of cross-desensitization to the inhibitory action of opioids upon EP indicates that the drugs exert their effects via different opioid receptors. Morphine and bremazocine predominantly inhibited the left cortex EP, whereas DADL was a potent inhibitor of the right cortex EP. Thus opioid receptors which modulate evoked electrical activity of the left visual cortex (LVC) apparently belong mostly to mu- and kappa-type while delta-receptors were predominantly responsible for the modulation of electrical activity in the right visual cortex (RVC). Application of LVC- and RVC-extracts to the cortex surface led to EP inhibition, which was partially (60-80%) prevented by antagonist naloxone. LVC-extract proved to be a more potent inhibitor of the left cortex EP, whereas RVC-extract was found to be more effective when applied to the right cortex. It is suggested that not only opioid receptors, but also their endogenous ligands are lateralized in turtle visual cortex.     

Evoked potentials in the rat neostriatum during local cooling of the cortex in the zone of primary response to the applied stimulus

The effect of local cooling of the surface of the somatosensory cortex was studied while recording primary response (PR) in the center of a cooled area and evoked potentials (EP) in the striatum to the forepaw stimulation. The cooling which served to arise the amplitude of the PR, served also to arise the amplitude of the EP in the striatum. EP to the stimulus, the sensory representation of which in the cortex was cooled, were facilitated only. Facilitation of the striatal EP was more intense than facilitation of the cortical PR in the cooled area. The level of facilitation of the EP was the same in the region of the striatum which receives corticofugal fibers from the cooled area of the cortex and in other regions of the striatum, receiving the corticofugal fibers from other parts of the cortex. The data show a possibility for the interactions in the striatum of the corticofugal signals from different cortical areas with each other and with the ascending afferent signals.     

Effect of beta-phenylethylamine on evoked potentials of the neostriatum of rats]

The effect of intraperitoneal (70 mg/kg) and local (39 ug) administration of beta-phenylethylamine (beta-PEA) on evoked potentials (EP) in the caudate nucleus upon stimulation of substantia nigra zona compacta (SNC) and frontal cortex in rats has been studied. beta-PEA, glutamate and haloperidol were injected into the caudate nucleus by means of a system consisting of a pushpull cannule and an electrode for simultaneous registration of EP. Specificity in the effect of the drugs on EP in response to stimulation of the cortex and substantia nigra was revealed. The intraperitoneal injection of beta-PEA induced, comparatively to the application, more rapid and potent decrease in the amplitude of the component (N2-P2) as a result of the substantia nigra stimulation and slightly influenced the EP amplitude in stimulation of the frontal cortex. It was established using haloperidol that the component (N2-P2) of EP in response to the substantia nigra stimulation is of dopaminergic neuron function in the nigro-neostrital system of the rat brain.     

Analysis of evoked potentials of the cerebellar cortex

Evoked potentials (EP) of the cerebellar cortex in response to stimulation of peripheral nerves are characterized by a two-phase positive-negative oscillation of the potential having a latent period of 10–25 msec. The electropositive phase can contain up to three components. The latent period of component I comprises 3–9 msec. The latent period and amplitude of this component are distinguished by considerable stability, which indicates the predominant significance of presynaptic processes in its formation. The sign of component II changes at a depth of 500 µ (and more), which corresponds to the position of the granular cell layer. At this level there arises in the neurons a response with a latent period of 4–10 msec in the form of a group (3–10) of impulses with a frequency of up to 200 per sec. It is concluded that the granular cells participate in the formation of component II and partially participate in the formation of components I and III of the EP. Responses to stimulation of the nerves appear synchronously with the EP in 24% of responding Purkinje cells; they fall on the maximum electropositive deviation or component III of the EP. Microinjections of 1% strychnine into the cerebellar cortex cause an increase of EP amplitude; impulse activity of the neurons is intensified. This indicates participation of postsynaptic processes in the formation of EP. No shifts in the EP of the cerebellar cortex were observed after intracortical injection of 0.1% atropine.N. I. Pirogov Vinnitsa Medical Institute. Translated from Neirofiziologiya, Vol. 2, No. 4, pp. 429–433, July–August, 1970.     

Dynamics of changes in somatosensory input to the motor cortex following lesion of somatosensory cortical areas in dogs

The pattern of change produced in somatosensory evoked potential (EP) in the forelimb projection area within the motor cortex (MI) following lesion of the projection area of the same limb in the somatosensory cortex (SI) or in parietal cortex area 5 was investigated during chronic experiments on waking dogs. Amplitude of the initial positive — negative wave of EP declined to 28–63% of preoperational level in all cases. No significant recovery of EP was noted for three weeks. Thus, a correlation between change in EP and spontaneous recuperation of the precision motor response occurring within two weeks after lesion of the SI did not exist. Nor was EP reinstated in the MI after ablation of area 5, despite complete but gradual reinstatement of EP (after an initial decline to 53%) in the nearby SI region. This protracted depression of EP seems to have been associated with breakdown of somatotopic sensory input from the SI or from area 5 to the MI, since EP in the motor cortex of the intact hemisphere and the hindlimb projection area within the MI on the lesioned side either remained unchanged or recovered within a week or two.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 1, pp. 61–68, January–February, 1990.     

Modulation of the neuronal activity and evoked potentials of the cerebral cortex by stimulation of the dorsal hippocampus]

In experiments on alert rabbits high frequency stimulation of the CA1 field of the dorsal hippocampus reduced the peak latency of the main negative component of the evoked potential (EP) to a light flash in the sensorimotor and occipital tests areas of the cerebral cortex. A single stimulation of the same part of the hippocampus resulted in a gradually developing facilitation of secondary negativity of the EP 5th component, predominantly in the sensorimotor cortex. Investigation of neuronal responses in the same cortical areas to a stimulation of the CA1 field with different parameters has shown that the effects of EP modulation are due to dynamic reorganizations of cortical neuronal activity.     

Studies on projections of somatic afferentation in the neocortex of the hedgehog Erinaceus europaeus]

Cortical projections of the somatic system in the hedgehog cortex were studied by means of the evoked potential (EP) technique. The EPs were shown to arise at a large area of the lateral cortex, the area in question being enlarged under chloralose anaesthesia. In the focus of projection of corresponding modalities the EPs posessed the least latency. Functional differences in the EP generation system both in the focus of projection and outside it are discussed. The wide EPs spreading in the lateral cortex as well as the presence of relatively differentiated projections is supposed to depend on the afferent volley dispersion to the polysynaptic pathways at the thalamic level. Considerable overlapping of sensory projection zones in the cortex is conditioned by the latter and indicates low degree of the somatic analyser organization.     

Evoked potentials of the auditory cortex of the porpoise,Phocoena phocoena

Summary Evoked potential (EP) recordings in the auditory cortex of the porpoise,Phocoena phocoena, were used to obtain data characterizing the auditory perception of this dolphin. The frequency threshold curves showed that the lowest EP thresholds were within 120–130 kHz. An additional sensitivity peak was observed between 20 and 30 kHz. The minimal EP threshold to noise burst was 3·10^–4–10^/s-3 Pa. The threshold for response to modulations in sound intensity was below 0.5 dB and about 0.1% for frequency modulations. Special attention was paid to the dependence of the auditory cortex EP on the temporal parameters of the acoustic stimuli: sound burst duration, rise time, and repetition rate. The data indicate that the porpoise auditory cortex is adapted to detect ultrasonic, brief, fast rising, and closely spaced sounds like echolocating clicks.Abbreviation EP evoked potential     

Analysis of auditory information in the brain of the cetacean

The cetacean brain specifics involve an exceptional development of the auditory neural centres. The place of projection sensory areas including the auditory that in the cetacean brain cortex is essentially different from that in other mammals. The EP characteristics indicated presence of several functional divisions in the auditory cortex. Physiological studies of the cetacean auditory centres were mainly performed using the EP technique. Of several types of the EPs, the short-latency auditory EP was most thoroughly studied. In cetacean, it is characterised by exceptionally high temporal resolution with the integration time about 0.3 ms which corresponds to the cut-off frequency 1700 Hz. This much exceeds the temporal resolution of the hearing in terranstrial mammals. The frequency selectivity of hearing in cetacean was measured using a number of variants of the masking technique. The hearing frequency selectivity acuity in cetacean exceeds that of most terraneous mammals (excepting the bats). This acute frequency selectivity provides the differentiation among the finest spectral patterns of auditory signals.     

Evoked potential correlates of early conditioning in the rat ontogeny.

In rats aged 2-8 weeks cortical EP to CS (20 flash - tone combinations, 0,9/sec, reinforced since the 10th application by electric shocks to the hind leg) were studied within different kinds of behavioral responses during avoidance learning and extinguishing. In contrast to our results in freely moving rats no developmental trend was found in this kind of avoidance (lifting of the hind leg). Average EP within reinforced trials (with escape or no reactions) differed in isolated application of CS from those when both CS and US were acting together. In younger animals the EP to CS combined with US were characterized by an evident late negative wave which shifted later (5-6 weeks toward the early negative complex. The EP changes in the auditory cortex were more pronounced, whereas visual EP with CS-US combination were rather decreased. In the youngest animals (2 weeks) the auditory EP within trials with avoidance were characterized by a distinct short latency deflection of the first positive wave, whereas in EP to extinguished CS the second deflection of the first positive wave prevailed. Also in these phenomena, the typical changes were clearly revealed in the auditory cortex. At later developmental stages (starting the 3rd, more prominently the 4th and 5th week) the wave following primary positive - negative complex was shifted toward the negativity if the animal responded by an avoidance; on the contrary an ample positive, often a double-peak wave arose if the response was extinguished. The stimulus and reaction dependence in the cortical EP showed the role of not yet fully mature cerebral cortex in avoidance learning. Both, fast as well as with some delay running processes participated in the observed phenomena during the ontogenetical development.     

Cortical representation of the heart sinus node zone

Evoked potentials (EP) arising in response to electrical stimulation of the heart sinus node zone (SNZ) were registered in the cortex of the large hemispheres (LHS) of cats. EP with the shortest latent period (LP) of 18-19 months were recorded both in the left and right hemispheres in the area of a cross-shaped cleft (associative field PCA, partially the I motorsensor zone and the I sensorimotor zone). Besides, EP with a more durable LP (20-21 months) were registered in the 2nd sensorimotor zone. EP remained unchanged after bilateral vagotomy and disappeared after spinal cord cutting at C-2 level. The presence of the functional centre regulating cardiac activity in the branch sections of LHS is suggested.     

Evoked potentials and electric resistance of the cerebral cortex under the effects of strychnine and atropine]

The effect of strychnine and atropine on the amplitude of the evoked potentials (EP) of the cerebral cortex was studied. It was shown, that both drugs increased amplitude of the EP. When we used strychnine, increased amplitude of the EP determined modification of the electrical resistance and current sources of the electrical field of the EP. Atropine did not change electrical resistance and in this case only electrical current sources determined modification of the EP.     

Dynamics of habituation in different cortical regions of the cat brain

The dynamics of habituation in the rostral part of the parietal association region and also in the first and second somatosensory areas was studied by the evoked potentials (EP) method in cats anesthetized with chloralose (80-90 mg/kg) and immobilized with flaxedil. During repeated stimulation of the splanchnic nerve brief habituation of EP developed in the cortex. It corresponded in its basic features to habituation observed in other sensory systems. On comparison of the rates of development of habituation in the primary and secondary projection zones of the splanchnic nerve in the cortex differences were found: habituation developed more rapidly in the secondary projection zones. The functional importance of this phenomenon is discussed.     

Functional maturation of the cat visual cortex during prenatal ontogenesis]

Development of the perceiving function of the visual cortex was studied on the foeti of cats in the second stage of antenatal development with intact placental blood circulation. It has been found that functional maturing of the cortical end of the visual analyser starts at the beginning of the second half of antenatal life. At this period EPs to stimulation of the optic nerve are recorded throughout the dorsal cortex of the contralateral hemisphere. At first they appear as slow three-phase (positive-negative-positive) oscillations of a small amplitude. As the foetus develops, the EP amplitude increases, and the EP configuration in the striate zone of the cortex becomes complex. Two weaks before birth, a short-latency negative wave appears against the background of the primary positive oscillation. In the last week of antenatal development of the foeti and in the first few days of the kittens life, EPs are represented in the specific zone of the visual cortex (g. lateralis) as two negative oscillations, and in the so-called associative zone (the middle part of the suprasylvian gyrus) by one long-latency high-amplitude negative oscillation which corresponds by latency to the second negative EP component in the striate cortex.     

Effect of positive and negative emotional states on the electrical activity of the auditory cortex in rabbit ontogeny

It has been shown that in all age groups of animals, self-stimulation of the hypothalamus is accompanied with the decrease in the latent period and the increase in the amplitude of the evoked potential (EP) in the auditory cortex. During negative stimulation, the increase in temporal parameters of the response takes place together with the decrease in the amplitude of the EP and the onset of secondary waves. Significant age changes were revealed in the recovery of the initial pattern of the EP after cessation of stimulation of emotiogenic zones. The recovery of the EP after stimulation of the "reward" zone in younger rabbits occurs 4 times faster than in adult animals, whereas in the former the recovery period of the EP after stimulation of the "punishment" zone is significantly longer.     

Evoked cortical potentials to simple and complex visual signals in children

The analysis of steadily recorded components of evoked potentials (EP) in different areas of cerebral cortex during tachistoscopic presentation of a homogeneous square, checker-board pattern and schematic drawings of human faces (face-pattern) of 6 degrees size was performed in children aged from 6,5 to 7 years. During contour detection, characterized by significant EP differences between responses to a checker-board pattern and a homogeneous square, the most pronounced changes were observed in the visual projection area of the cortex. Reaction to a complex visual stimulus, characterized by differences of EP to fase and checker-board patterns, had maximal manifestation in the temporo-parieto-occipital area. The changes observed during both operations were noted for EP components appearing up to 250 msec following stimulation. It is suggested that they are connected with the activity of cortical receptive fields. The data obtained are discussed on the basis of hypothesis of a difference between cortical mechanisms of single operations involved in visual perception.     

Berberine regulates the expression of E-prostanoid receptors in diabetic rats with nephropathy

Diabetic nephropathy (DN) is a major cause of morbidity and mortality in diabetic patients. Effective therapies to prevent the development of this disease and to improve advanced kidney injury are required. Berberine (BBR) has preventive effects on diabetes and its complications. This study is to investigate the effects of BBR on the expression of E-prostanoid receptors (EPs) in rats with high-fat diet and streptozotocin (STZ)-induced DN and underlying molecular mechanisms of BBR on DN rats. DN model was induced in male Sprague–Dawley rats with high-fat diet and low dose of STZ injection. BBR (50, 100, 200 mg/kg/d) were orally administered to rats after STZ injection and conducted for 8 weeks. The levels of interleukin-6 (IL-6) and prostaglandin E₂ (PGE₂) in renal cortex were measured by enzyme-linked immunosorbent assay. Expression of EPs receptors (EP1–EP4) were determined by western blotting. Remarkable renal damage, hyperglycemia and hyperlipidemia were observed in DN rats. BBR could restore renal functional parameters, suppress alterations in histological and ultrastructural changes in the kidney tissues, improve glucose and lipid metabolism disorders, and increase cAMP levels compared with those of DN model group (Wang et al. in Mol Biol Rep 40:2405–2418, 2013). The level of IL-6 and PGE₂ were significantly increased in DN model group compared with normal group, BBR could apparently reduced the level of IL-6 and PGE₂. Furthermore, the expression of EP1 and EP3 were both increased and EP4 was lessened in the DN model group compared with normal group, BBR could down-regulate total protein expression of EP1 and EP3 of renal cortex in DN rats and up-regulate the expression of EP4, and there is no significant difference on the expression of EP2 among all groups. These studies demonstrate, for the first time, that BBR exerts renoprotection in high-fat diet and STZ-induced DN rats by modulating the proteins expression of EPs in EP–G protein–cAMP signaling pathway.     

Evoked potentials of the auditory cortex on paired stimuli

Changes in the responsiveness of the auditory cortex to an acoustic click and to direct stimulation of the medial geniculate body were studied by the method of evoked potentials in an extended experiment on cats with implanted electrodes. It is shown that the minimum interval between two stimuli for which a second click produces an EP in the auditory cortex is from 30 to 50 msec. The relative refractory period consists of two parts. The first (50–100 msec) is characterized by a rapid recovery, and the second (about 500 msec) by a slow recovery. In contrast with a click, direct stimulation of the geniculate body does not produce a refractory condition but one of facilitation. The effects of Nembutal and chloralose anesthesia and the state of alertness on the recovery of auditory cortex responsiveness were investigated. The reason for the absence and the reduction of an EP from the auditory cortex to a testing click during absolute and relative refractory periods is not a passive decrease of excitability of the usual refractory kind, but an active interplay of excitatory and inhibitory processes in the cerebral cortex, geniculate bodies, and reticular formation of the brain stem.A. A. Bogomolets' Institute of Physiology, Academy of Sciences, Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 1, No. 1, pp. 54–64, July–August, 1969.     

Dynamics of evoked potentials in the auditory zone of the dog cerebral cortex following extirpation of the medial geniculate bodies during formation of goal-directed behavior]

Integrative processes in the auditory cortical zone were studied in three dogs by EEG and EP parameters during the formation of a defensive reaction to clicks (four clicks, two per second) after the extirpation of the medial geniculate bodies. In the operated animals information is transmitted to the cortical end of the auditory analyser by compensatory paths with a larger number of relays. In the auditory cortex EPs are recorded with a longer latency (12 to 16 msec), and the duration of the negative EP component is increased (up to 40 msec). It is split mainly on the ascending front. The cortical end of the analyser participates in the formation of processes of afferent synthesis. In the active period of reflex elaboration the inflow of information increases: the EP amplitude and the duration of its main negative component become greater (up to 45-55 msec), as well as the splits on its fronts. In the course of preparing for a decision, before the achievement of the conditioned reaction, a "double EP" appears, which is due to enhanced reverberation of excitations in the compensatory paths.     

Polysensory properties of the horizontal region of the diagonal bundle from the cat forebrain

Sharply different wave forms and parameters of averaged evoked potentials (EP) in response to single visual and somatic stimuli were observed in the same points of the horizontal limb nucleus of the diagonal band (NDB) in cats under nembutal anesthesia. The existence of heterogenic EPs in NDB makes it possible to consider this part of the nucleus as a polysensory structure. Decreased EP latency, as compared to that in the neocortex, indicates that heterogenic impulses reach NDB by higher speed Ways than the cortex. The comparison of NDB EP refractory periods during paired stimulation of one or different sensory systems shows that polyvalent impulses affect independently functioning neuronal populations. It is suggested that a common principle of specific heterogenic signals arrival to distinct neuronal complexes exists for polysensory structures at different levels of the central nervous system.