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Grossman SP. Neurophysiologic aspects: extrahypothalamic factors in the regulation of food intake. ADVANCES IN PSYCHOSOMATIC MEDICINE 2015; 7:49-72. [PMID: 4633835 DOI: 10.1159/000393294] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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2
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Fedotova IR, Frolov AA. [Septal Activation and Control of Limbic Structures]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2015; 65:139-155. [PMID: 26080595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Coherent activation of limbic system structures as the main function of theta-rhythm is widely discussed in the literature. However until now does not exist the common view on its generation in these brain structures. The model of septal theta-rhythmic activation and control of limbic structures is suggested basing on the literature and own experimental data.
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Brandon MP, Bogaard AR, Libby CP, Connerney MA, Gupta K, Hasselmo ME. Reduction of theta rhythm dissociates grid cell spatial periodicity from directional tuning. Science 2011; 332:595-9. [PMID: 21527714 PMCID: PMC3252766 DOI: 10.1126/science.1201652] [Citation(s) in RCA: 298] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Grid cells recorded in the medial entorhinal cortex of freely moving rats exhibit firing at regular spatial locations and temporal modulation with theta rhythm oscillations (4 to 11 hertz). We analyzed grid cell spatial coding during reduction of network theta rhythm oscillations caused by medial septum (MS) inactivation with muscimol. During MS inactivation, grid cells lost their spatial periodicity, whereas head-direction cells maintained their selectivity. Conjunctive grid-by-head-direction cells lost grid cell spatial periodicity but retained head-direction specificity. All cells showed reduced rhythmicity in autocorrelations and cross-correlations. This supports the hypothesis that spatial coding by grid cells requires theta oscillations, and dissociates the mechanisms underlying the generation of entorhinal grid cell periodicity and head-direction selectivity.
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Hydén H. The learning brain during a life-cycle - some biochemical and psychological aspects. ACTA NEUROLOGICA SCANDINAVICA. SUPPLEMENTUM 2009; 80:9-27. [PMID: 7008490 DOI: 10.1111/j.1600-0404.1980.tb02346.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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5
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Olton DS. The function of septo-hippocampal connections in spatially organized behaviour. CIBA FOUNDATION SYMPOSIUM 2008:327-49. [PMID: 252445 DOI: 10.1002/9780470720394.ch13] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The role of septo-hippocampal connections in spatial behaviour is examined in lesion and stimulation experiments in rats. Destruction of septo-hippocampal connections produces a severe and enduring deficit in the ability to perform a spatial memory task. Furthermore, crossed unilateral lesions of the entorhinal area and fimbria-fornix produce the same deficit as bilateral lesions in either the entorhinal area or the fimbria-fornix, as predicted from a disconnection analysis of hippocampal lesions. Evidence also suggests that septo-hippocampal damage produces a greater deficit in spatial behaviours when a flexible response is required than when a consistent response is required, although this difference is a relative one rather than an absolute one. Finally, disruptive stimulation of the hippocampus while rats are performing a spatial memory task produces retrograde amnesia but not proactive interference. Taken together, these data indicate an important role of the septo-hippocampal system in spatial behaviour, and in the maintenance of spatial memories.
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Gray JA, Feldon J, Rawlins JN, Owen S, McNaughton N. The role of the septo-hippocampal system and its noradrenergic afferents in behavioural responses to none-reward. CIBA FOUNDATION SYMPOSIUM 2008:275-307. [PMID: 32018 DOI: 10.1002/9780470720394.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Our experiments were designed with two purposes: (i) to examine the effects on one behaviour of differing interventions in the septo-hippocampal system; (ii) to compare these effects with those of minor tranquillizers. The behaviour studied (in rats) is extinction in the alley after continuous (CRF) or partial (PRF) reinforcement. Minor tranquillizers and large septal lesions produce three effects: (1) resistance to extinction is increased after CRF; (2) resistance to extinction is decreased after PRF; (3) the partial reinforcement extinction effect (PREE) is abolished. Small septal lesions fractionate this syndrome: either effect (1) or an actual increase in the size of the PREE is produced by medial septal lesions abolishing hippocampal theta; effects (2) and (3), but not (1), are produced by lateral septal lesions sparing theta. Dorso-medial fornix section, abolishing theta, reproduces the effects of medial septal lesions. Fimbrial section, sparing theta, reproduces some of the effects of lateral septal lesions. Minor tranquillizers produce a rise in the threshold for septal driving of hippocampal theta specifically at 7.7 Hz. This effect is reproduced by blockade of noradrenergic transmission or destruction of the dorsal noradrenergic bundle with 6-hydroxydopamine. This lesion reproduces all three behavioural changes listed above. These results suggest a model for the role of the septo-hippocampal system and its noradrenergic inputs in the PREE. This model is compared with other approaches to the septo-hippocampal system.
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Defrance JF, Stanley JC, Marchand JE, Chronister RB. Cholinergic mechanisms and short-term potentiation. CIBA FOUNDATION SYMPOSIUM 2008:109-26. [PMID: 215388 DOI: 10.1002/9780470720394.ch7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Acutely prepared rabbits were used to study, electrophysiologically, tetanic and post-tetanic potentiation of the pathway from the medial septal region to hippocampal field CA1. It was found that tetanic potentiation, evoked by short stimulus trains, was maximal at 6--8 Hz. Responses recovered from post-tetanic potentiation in 5--35 seconds. Acetylcholine, physostigmine, and cyclic GMP each had an excitatory effect on pyramidal cell responses when applied in stratum radiatum. The time course studies showed that these effects outlasted the duration of the injection current by many minutes. Phosphodiesterase inhibitors (e.g., isobutyl methyl xanthine) prolonged the time course of recovery with test responses which were post-tetanically potentiated. K+, on the other hand, selectively enhanced tetanic potentiation. It is suggested, with respect to the potentiation phenomena, that K+ acted primarily presynaptically to facilitate transmitter release, whereas cyclic GMP acted primarily postsynaptically for the enhancement of pyramidal cell excitability.
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Vinogradova OS, Brazhnik ES. Neuronal aspects of septo-hippocampal relations. CIBA FOUNDATION SYMPOSIUM 2008:145-77. [PMID: 215389 DOI: 10.1002/9780470720394.ch8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In unanaesthetized, conscious rabbits, in unstressful conditions, the neurons of the hippocampus and septum were investigated extracellularly during the presentation of a series of varied sensory stimuli. In the normal hippocampus these stimuli evoke habituating reactions of tonic (more usually, inhibitory) type in field CA3, with the addition of 'specific' patterned, and phasic reactions in field CA1. After complete septo-hippocampal disconnection the proportion of tonic (especially, of inhibitory) reactions in the hippocampus decreases. Theta bursts in the neuronal activity are absent; reactions to repeated sensory stimuli do not habituate. After lesion of the cortical perforant path to the hippocampus the majority of reactions in both fields are of tonic type. The proportion of neurons with regular theta bursts increases. Habituation is completely absent. A high correlation appears between the sensory reactions and the effects of midbrain reticular formation stimulation in the same neurons. The combination of both lesions does not significantly change the spontaneous activity of hippocampal neurons (except for the absence of the theta bursts). An increase in the level of activity of hippocampal neurons (by physostigmine), or rhythmic stimulation of the remaining synaptic systems, does not restore their rhythmic theta activity. In the septum deprived of hippocampal input the normal level of reactivity to sensory stimuli and the normal types of reaction are preserved. The proportion of neurons with theta bursts increases. The typical linear and rapid habituation of reactions disappears and is replaced by an unlimited increment in effects during repeated presentations of sensory stimuli. Discussion concerns the synchronizing and inhibitory influences of the septum on the hippocampus, and the role of the hippocampus in the organization of decremental processes (habituation) in the septum and brainstem structures.
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Lynch G, Rose G, Gall C. Anatomical and functional aspects of the septo-hippocampal projections. CIBA FOUNDATION SYMPOSIUM 2008:5-24. [PMID: 83225 DOI: 10.1002/9780470720394.ch3] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The origins, distribution, and cellular targets of the septo-hippocampal projections are reviewed. It appears that the distribution of acetylcholinesterase-positive neurons in the medial septum and diagonal bands and those cells labelled after injections of horseradish peroxidase into the hippocampus coincide; however, the possibility of a non-acetylcholinesterase septal projection remains. Good agreement is found between the distribution of hippocampal acetylcholinesterase and the patterning of silver grains after injection of [3H]leucine into the medial septum. A major target of septal efferents to the hippocampus is the interneuron population; the possibility of septal mediation of intrahippocampal circuitry via this anatomical arrangement is discussed.
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Vanderwolf CH, Kramis R, Robinson TE. Hippocampal electrical activity during waking behaviour and sleep: analyses using centrally acting drugs. CIBA FOUNDATION SYMPOSIUM 2008:199-226. [PMID: 252441 DOI: 10.1002/9780470720394.ch10] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Rhythmical slow activity (RSA) occurs in the hippocampus under many conditions including waking behaviour, active sleep and surgical anaesthesia. Under all these conditions RSA, apparently, is produced by the coupled operation of CA1 and dentate gyrus generators. Two ascending brainstem systems appear capable of initiating activity in these coupled generators. One system, ascending via the diagonal band and medial septal nucleus, may contain cholinergic synapses since it is blocked by atropine and stimulated by eserine. The RSA produced by this system usually has a frequency of 4--7 Hz and can occur during total immobility during the waking state, active sleep or anaesthesia. A second ascending system produces RSA of higher frequency (usually 7--12 Hz) and is active during waking if, and only if, movements such as walking occur. During active sleep this system is active only during phasic muscular twitches. Anaesthetics (ether, urethane) and morphine abolish activity in this second system but it is resistant to atropinic and nicotinic drugs. Amphetamine stimulates, and major tranquillizers depress the atropine-resistant system but these drugs do not abolish its normal relation to behaviour. Neocortical activity appears to be controlled by two ascending systems which parallel closely those ascending to the hippocampus.
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Abstract
After tetanization of several hippocampal pathways (10--50 Hz for 5--15 seconds) there is an increased synaptic transmission of long duration (long-lasting facilitation). The present investigation was undertaken on isolated hippocampal slices to study the mechanism of the effect. The transverse hippocampal slice preparation in vitro allows the simultaneous testing of several afferent fibre systems on the same cell or population of cells. Tetanization of one group of afferent fibres to CA1 pyramids was followed by a long-lasting increase of synaptic transmission along the same fibres, whereas a control input line gave unchanged responses. Using the presynaptic volley as an indicator of the number of afferent impulses, the increased synaptic transmission appeared as an increased excitatory postsynaptic potential (EPSP), increased amplitude and reduced latency of the population spike, and an increased probability of firing of single units. Intracellular recording showed increased EPSPs to afferents of the tetanized line, but no lasting change in membrane resistance or in the response to a depolarizing current pulse. Thus, the effect cannot be ascribed to a general postsynaptic excitability increase. The specific changes in the synaptic transmission may be due either to an increased amount of liberated transmitter or to a local postsynaptic change near the tetanized synapses.
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12
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Ursin H, Dalland T, Ellertsen B, Herrmann T, Johnsen TB, Livesey P, Zaidi Z, Wahl H. Multivariate analysis of the septal syndrome. CIBA FOUNDATION SYMPOSIUM 2008:351-72. [PMID: 252446 DOI: 10.1002/9780470720394.ch14] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Since recent reviews of the behavioural effects of septal lesions agree that more than one explanatory concept is required, a multivariate analysis of the septal syndrome has been made. A total of 127 rats have been tested 73 with septal lesions and 54 controls. The rats were tested in a standard test battery consisting of a residential maze, spontaneous alternation, spatial learning, approach/avoidance conflict and one-way active avoidance. Factor analyses reveal a complex change in the factor structure after septal lesions. None of the previous explanations of septal functions receives unequivocal support. The findings do not exclude the possibility that septal lesions interfere with a few general behaviour mechanisms or perhaps only one. However, if so, this factor does not explain as much of the variance as expected. Situational or test-dependent factors play a greater role in the variance. This is interpreted as an indication of insufficiency in the theoretical structure, or in conventional test designs.
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Okabe M. [Observation of sperm-egg interaction through gene-manipulated animals]. SEIKAGAKU. THE JOURNAL OF JAPANESE BIOCHEMICAL SOCIETY 2006; 78:1062-72. [PMID: 17176894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
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14
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Needelman H, Schroeder B, Sweney M, Schmidt J, Bodensteiner JB, Schaefer GB. Ontogeny and physiology of the cavum septum pellucidum in premature infants. J Child Neurol 2006; 21:298-300. [PMID: 16900925 DOI: 10.1177/08830738060210041501] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report the natural history of the closure of the cavum septum pellucidum in 47 premature infants. In this study, a cavum septum pellucidum was present in all patients at 25 to 26 weeks' postconceptual age, in keeping with previous reports. The data from this study suggest that premature delivery does not change the natural history of the normal closure of the cavum septum pellucidum in most infants by 36 to 40 weeks' postconceptual age. Although not statistically significant, there is a suggestion from these data that higher grades of intraventricular hemorrhage are more frequently associated with loss (early closure) of the cavum septum pellucidum. One particularly illustrative case with a grade 4 intraventricular hemorrhage and subsequent hydrocephalus suggests that increases in pressure and volume in the lateral ventricles can cause the laminae of the septum pellucidum to approximate and appear to fuse earlier than expected. However, the fact that the cavum septum pellucidum reappeared in this case after ventricular pressure was decreased (postventricular shunt) suggests that approximation is not the sole factor in definitive fusion of the laminae of the septum pellucidum.
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Jonasson Z, Cahill JFX, Tobey RE, Baxter MG. Sexually dimorphic effects of hippocampal cholinergic deafferentation in rats. Eur J Neurosci 2005; 20:3041-53. [PMID: 15579159 DOI: 10.1111/j.1460-9568.2004.03739.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
To determine whether the basal forebrain-hippocampal cholinergic system supports sexually dimorphic functionality, male and female Long-Evans rats were given either selective medial septum/vertical limb of the diagonal band (MS/VDB) cholinergic lesions using the neurotoxin 192 IgG-saporin or a control surgery and then postoperatively tested in a set of standard spatial learning tasks in the Morris water maze. Lesions were highly specific and effective as confirmed by both choline acetyltransferase/parvalbumin immunostaining and acetylcholinesterase histochemistry. Female controls performed worse than male controls in place learning and MS/VDB lesions failed to impair spatial learning in male rats, both consistent with previous findings. In female rats, MS/VDB cholinergic lesions facilitated spatial reference learning. A subsequent test of learning strategy in the water maze revealed a female bias for a response, relative to a spatial, strategy; MS/VDB cholinergic lesions enhanced the use of a spatial strategy in both sexes, but only significantly so in males. Together, these results indicate a sexually dimorphic function associated with MS/VDB-hippocampal cholinergic inputs. In female rats, these neurons appear to support sex-specific spatial learning processes.
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Ma J, Shen B, Rajakumar N, Leung LS. The medial septum mediates impairment of prepulse inhibition of acoustic startle induced by a hippocampal seizure or phencyclidine. Behav Brain Res 2004; 155:153-66. [PMID: 15325789 DOI: 10.1016/j.bbr.2004.04.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2003] [Revised: 04/13/2004] [Accepted: 04/13/2004] [Indexed: 02/05/2023]
Abstract
The involvement of the septohippocampal system on the impaired sensorimotor gating induced by phencyclidine (PCP) or by an electrically induced hippocampal seizure was examined in behaving rats. An impaired sensorimotor gating, measured by prepulse inhibition (PPI) of the acoustic startle response, was observed following a hippocampal afterdischarge (AD) or systemic injection of PCP and was accompanied with an increase in hippocampal gamma waves (30-70 Hz). The medial septum infusion with muscimol (0.25 microg), a GABA(A) receptor agonist, 15 min prior to PCP or a hippocampal AD, prevented the impairment of sensorimotor gating and the increase in gamma waves. By itself, muscimol (0.25 microg) injection into the medial septum did not affect PPI, although it significantly suppressed spontaneous gamma waves. In order to identify subpopulations of neurons mediating the sensorimotor gating deficit and the hippocampal gamma wave increase, 0.14-0.21 microg of p75 antibody conjugated to saporin (192 IgG-saporin) was injected into the medial septum to selectively lesion the septohippocampal cholinergic neurons. Neither the PPI deficit nor the gamma wave increase induced by PCP or a hippocampal AD was affected by 192 IgG-saporin lesion of the medial septum. It is concluded that increase in neural activity in the medial septum participates in the impairment of sensorimotor gating and the increase in hippocampal gamma waves induced by PCP or a hippocampal AD. It is suggested that the GABAergic but not the cholinergic septohippocampal neurons mediate the sensorimotor gating deficit.
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Winters BD, Dunnett SB. Selective lesioning of the cholinergic septo-hippocampal pathway does not disrupt spatial short-term memory: a comparison with the effects of fimbria-fornix lesions. Behav Neurosci 2004; 118:546-62. [PMID: 15174932 DOI: 10.1037/0735-7044.118.3.546] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rats receiving intrahippocampal injections of 192 IgG-saporin (SAP-HPC), fimbria-fornix lesions (FF), or sham control surgeries were tested in a series of delayed matching (DMTP)- and nonmatching (DNMTP)-to-position tasks. The FF group was significantly impaired on a pretrained DNMTP task relative to the control and SAP-HPC groups, which did not differ. All groups then acquired a matching-to- position rule at the same rate, and only the FF group showed a delay-dependent deficit when longer retention intervals were introduced for DMTP testing. Results demonstrate the importance of the fimbria-fornix fiber system in spatial short-term memory but suggest that the cholinergic septohippocampal component of this pathway is not required for successful delayed matching (or nonmatching)-to-position performance.
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Brazhnik ES. [Theta rhythmicity in the medial septum: entraining by the GABA-ergic neurons]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2004; 54:192-201. [PMID: 15174264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
The medial septal/diagonal band complex (MS/DB) is believed to play an important role in the generation and maintenance of the hippocampal theta rhythm, which has been implicated in the mnemonic and information-processing capacity of the brain. Although the physiological and morphological diversity of the septal neurons indicates their different functions, it is not known which cell type within the population contributes most critically to the theta rhythm. Here we review the chemical identity of different cell groups within the MS/DB complex, the anatomical connectivity between them, the electrophysiological properties of immunochemically-defined cell types, and their contribution to theta rhythmicity in the medial septum and the hippocampal theta rhythm. In order to better understand the mechanisms involved in rhythmic burst firing of the MS/DB neurons, a number of relevant theoretical models related to the generation/synchronization in neural networks are discussed.
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Popova II. [The role of medial septal area in the neural control over hibernation]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2004; 54:163-73. [PMID: 15174261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Hibernation (winter sleep) is a kind of unique adaptive behavior of small mammals subjected to fine and complex central control. One of the most promising approaches to this problem is a search for the mechanisms providing brain control under conditions of a sharp decrease in temperature, (virtually, to zero) and metabolic rate. Studies conducted at the Laboratory of System Organization of Neurons under the supervision of Professor O.S. Vinogradova confirmed the hypothesis of the special role of the septohippocampal system in the control of winter sleep. Together with a brief characterization of hibernation in general, the data obtained at the Laboratory are also summarized in the review. The experimental evidence for the role of the medial septal area as a "sentry post" in hibernation is presented.
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Borisiuk RM. [Simulation of the hippocampal theta rhythm]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2004; 54:85-100. [PMID: 15069818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Centre of Theoretical and Computational Neuroscience, University of Plymouth, UK Basing on the hypothesis about the mechanisms of the theta rhythm generation, the article presents mathematical and computational models of theta activity in the hippocampus. The problem of the theta rhythm modeling is nontrivial because the slow theta oscillations (about 5 Hz) should be generated by a neural system composed of frequently firing neural populations. We studied a model of neural pacemakers in the septum. In this model, the pacemaker follows the frequency of the external signal if this frequency does not deviate too far from the natural frequency of the pacemaker, otherwise the pacemaker returns to the frequency of its own oscillations. These results are in agreement with the experimental records of medial septum neurons. Our model of the septal pacemaker of the theta rhythm is based on the hypothesis that the hippocampal theta appears as a result of the influence of the assemblies of neurons in the medial septum which are under control of pacemaker neurons. Though the model of the pacemaker satisfies many experimental facts, the synchronization of activity in different neural assemblies of the model is not as strong as it should be. Another model of the theta generation is based on the anatomical data about the existence of the inhibitory GABAergic loop between the medial septum and the hippocampus. This model shows stable oscillations at the frequency of the theta rhythm in a broad range of parameter values. It also provides explanation to the experimental data about the variation of the frequency and the amplitude of the theta rhythm under different external stimulations of the system. The role of the theta rhythm for information processing in the hippocampus is discussed.
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Kriukov VI. [Attention and memory model based on the principle of dominant and comparative function of the hippocampus]. ZHURNAL VYSSHEI NERVNOI DEIATELNOSTI IMENI I P PAVLOVA 2004; 54:11-31. [PMID: 15069813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Six basic problems of attention are described in terms of the dominant focus by Ukhtomsky, which is simulated as a system of phase transitions in the brain. Theoretical and experimental arguments in favor of the existence of metastable states in the brain with the life time of about a second or more are deduced. This forms an approach to resolution of all the problems of interaction between attention and memory, binding, and central control. A neurobiological model of attention and memory is advanced, which integrates the system properties of dominanta by A.A. Ukhtomsky and comparator function of the hippocampus by O.S. Vinogradova. New literature evidence is given for the existence of the brain system of information processing with the hippocampus as a central executive.
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Bielarczyk H, Tomaszewicz M, Madziar B, Cwikowska J, Pawełczyk T, Szutowicz A. Relationships between cholinergic phenotype and acetyl-CoA level in hybrid murine neuroblastoma cells of septal origin. J Neurosci Res 2003; 73:717-21. [PMID: 12929139 DOI: 10.1002/jnr.10711] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
High susceptibility of cholinergic neurons to neurotoxic signals may result from their utilization of acetyl-CoA for both energy production and acetylcholine synthesis. SN56 cholinergic cells were transfected stably with cDNA for choline acetyltransferase. Transfected cells (SN56ChAT2) expressed choline acetyltransferase activity and acetylcholine content, 17 times and 2 times higher, respectively, than did nontransfected cells. Transfection did not change pyruvate dehydrogenase but decreased the acetyl-CoA level by 62%. Differentiation by cAMP and retinoic acid caused an increase of choline acetyltransferase activity and decrease of acetyl-CoA levels in both cell lines. Negative correlation was found between choline acetyltransferase activity and acetyl-CoA level in these cells. SN56ChAT2 cells were more susceptible to excess NO than were native SN56 cells, as evidenced by the thiazolyl blue reduction assay. Thus, the sensitivity of cholinergic neurons to pathologic conditions may depend on the cholinergic phenotype-dependent availability of acetyl-CoA.
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Lehmann O, Grottick AJ, Cassel JC, Higgins GA. A double dissociation between serial reaction time and radial maze performance in rats subjected to 192 IgG-saporin lesions of the nucleus basalis and/or the septal region. Eur J Neurosci 2003; 18:651-66. [PMID: 12911761 DOI: 10.1046/j.1460-9568.2003.02745.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cholinergic basal forebrain has been implicated in aspects of cognitive function including memory and attention, but the precise contribution of its major components, the basalocortical and the septohippocampal systems, remains unclear. Rats were subjected to lesions of either the nucleus basalis magnocellularis (Basalis), the medial septum/vertical limb of the diagonal band of Broca (Septum), or both nuclei (Basalis + Septum), using the selective cholinotoxin 192 IgG-saporin. Cognitive performance was evaluated in tasks taxing attention (the five-choice serial reaction time task, 5-CSRTT) and spatial working memory (radial arm maze, RAM). Nucleus basalis lesions disrupted performance of the 5-CSRTT, as demonstrated by decreased choice accuracy, increased incidence of missed trials, increased latencies to respond correctly, and a disrupted pattern of response control. Combined lesions of the Basalis and Septum resulted in qualitatively similar deficits to Basalis lesions alone, although interestingly, these rats were unimpaired on measures of response speed, and showed weaker deficits on accuracy and omissions. Decreasing the attentional load by lengthening stimulus duration reversed some of the deficits in Basalis and Basalis + Septum rats, suggesting an attentional deficit rather than motivation or motor perturbations. Performance in rats with septal lesions was only affected when task difficulty was increased. In the RAM an opposing pattern of effects was observed, with Septum and Basalis + Septum rats showing dramatic impairments, and Basalis rats performing normally. Taken together, these data provide clear evidence for a functional dissociation between septohippocampal and basalocortical cholinergic systems in aspects of cognitive function.
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Grivas I, Michaloudi H, Batzios C, Chiotelli M, Papatheodoropoulos C, Kostopoulos G, Papadopoulos GC. Vascular network of the rat hippocampus is not homogeneous along the septotemporal axis. Brain Res 2003; 971:245-9. [PMID: 12706241 DOI: 10.1016/s0006-8993(03)02475-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Qualitative and quantitative image analysis of hippocampal vascular bed, after transcardial perfusion of India ink, reveals significant differences among hippocampal subfields and along the septotemporal axis of the rat hippocampus. Ventral hippocampus exhibits significantly higher levels of vascularization compared to dorsal hippocampus, which, however, is characterized by significantly higher capillary density. These results may explain the selective ischemia vulnerability of hippocampus along its septotemporal axis.
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Pang KC, Nocera R, Secor AJ, Yoder RM. GABAergic septohippocampal neurons are not necessary for spatial memory. Hippocampus 2002; 11:814-27. [PMID: 11811676 DOI: 10.1002/hipo.1097] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The medial septum/vertical limb of the diagonal band of Broca (MSDB) provides a major input to the hippocampus and is important for spatial memory. Both cholinergic and GABAergic MSDB neurons project to the hippocampus, and nonselective lesions of the MSDB or transections of the septohippocampal pathway impair spatial memory. However, selective lesions of cholinergic MSDB neurons using 192-IgG saporin (SAP) do not impair or only mildly impair spatial memory. Previously, intraseptal kainic acid was found to reduce levels of glutamic acid decarboxylase, a marker of GABAergic neurons, but not to alter the levels of choline acetyltransferase, a marker of cholinergic neurons. The present study further characterized the effects of kainic acid on GABAergic MSDB neurons and examined the effects of intraseptal kainic acid on spatial memory. Saline, kainic acid, SAP, or the combination of kainic acid and SAP was administered into the MSDB of rats. Spatial memory was assessed in an eight-arm radial maze and a water maze. Kainic acid destroyed GABAergic septohippocampal neurons, but spared cholinergic neurons. SAP eliminated MSDB cholinergic neurons, sparing noncholinergic neurons. Coadministration of kainic acid and SAP destroyed GABAergic and cholinergic MSDB neurons. Acquisition of the radial maze task and performance on this task with 4-h delays were unimpaired by intraseptal kainic acid or SAP, but were impaired by coadministration of kainic acid and SAP. Acquisition of the water maze task was unaffected by intraseptal kainic acid, delayed slightly by SAP, and impaired severely by coadministration of kainic acid and SAP. These results provide evidence that kainic acid at appropriate concentrations effectively destroys GABAergic septohippocampal neurons, while sparing cholinergic MSDB neurons. Furthermore, lesions of the GABAergic septohippocampal neurons do not impair spatial memory. While lesions of cholinergic MSDB neurons may mildly impair spatial memory, the combined lesion of GABAergic and cholinergic septohippocampal neurons resulted in a memory impairment that was greater than that observed after a selective lesion to either population. Thus, damage of GABAergic or cholinergic MSDB neurons, which together comprise the majority of the septohippocampal pathway, cannot totally account for the spatial memory impairment that is observed after nonselective lesions of the MSDB.
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