The Role of the Septohippocampal Pathway in the Regulation of Hippocampal Field Activity and Behavior: Analysis by the Intraseptal Microinfusion of Carbachol, Atropine, and Procaine

Lawson, Victoria H.; Bland, Brian H.

doi:10.1006/exnr.1993.1047

Cited by 130 publications

(97 citation statements)

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“…In contrast to higher frequencies of stimulation-elicited (Ͼ6 Hz) (Bland and Vanderwolf, 1972), intensities of RPO stimulation resulting in 4 -5 Hz resulted in a relatively stationary waveform over the 20 sec sample. Samples (20 sec from stimulation onset) of field and cell activity were subsequently taken during the same level of RPO stimulation after hippocampal was abolished by infusing procaine (2.0 l) into the MS/vDBB region (Brücke et al, 1959;Mizumori et al, 1989;Kirk and McNaughton, 1993;Lawson and Bland, 1993). Cell discharge (spontaneous and stimulated every 2 min) was sampled until hippocampal recovered.…”

Section: Methodsmentioning

confidence: 99%

Evidence for Differential Control of Posterior Hypothalamic, Supramammillary, and Medial Mammillary Theta-Related Cellular Discharge by Ascending and Descending Pathways

et al. 1996

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Single-unit discharge was recorded from cells in the posterior hypothalamic nucleus (PH), supramammillary nucleus (SuM), and medial mammillary nucleus (MM) during hippocampal theta () elicited by stimulation of the reticular nucleus pontis oralis (RPO). In agreement with previously published work, -related cells in the PH (12 cells) were all classified as tonic -ON (increased tonic discharge rate during hippocampal ), whereas those in the SuM (9 cells) and MM (15 cells) were all classified as phasic -ON (rhythmic discharge, in phase with ongoing ). The effect of RPO stimulation on cell discharge was tested after hippocampal was abolished by infusion of procaine into the medial septum/vertical limb of the diagonal band. The RPOelicited discharge patterns of all PH tonic -ON cells and all SuM phasic -ON cells survived septal procaine infusion. Further, the discharge rate of PH cells and the frequency of burst discharge of SuM cells during RPO stimulation both increased after the infusion. In contrast, septal procaine infusion abolished the RPO-elicited rhythmic discharge pattern in MM phasic -ON cells and attenuated their discharge rates. These results indicate that the PH and SuM form parts of an ascending system mediating hippocampal , whereas the MM receives (and perhaps relays to other parts of the limbic system) rhythmic input descending from the septo-hippocampal system. In addition, PH and SuM receive descending inputs that limit the discharge rates of their -related cells during hippocampal .

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Section: Methodsmentioning

confidence: 99%

Evidence for Differential Control of Posterior Hypothalamic, Supramammillary, and Medial Mammillary Theta-Related Cellular Discharge by Ascending and Descending Pathways

et al. 1996

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“…Because of the large cholinergic projection to the hippocampus from the medial septal nucleus, it was suspected that theta generation in the hippocampus depends critically on cholinergic input. However, cholinergic (muscarinic) antagonists do not block the theta activity that occurs during running (Lawson and Bland, 1993). In contrast, the theta that occurs during alert immobility, a condition where the animal may be responding to novel stimuli, is blocked by cholinergic antagonists.…”

Section: The Argument For Two Theta States: One For Learning and One mentioning

confidence: 99%

Storage, recall, and novelty detection of sequences by the hippocampus: Elaborating on the SOCRATIC model to account for normal and aberrant effects of dopamine

Lisman¹,

Otmakhova²

2001

Hippocampus

131

167

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ABSTRACT:In order to understand how the molecular or cellular defects that underlie a disease of the nervous system lead to the observable symptoms, it is necessary to develop a large-scale neural model. Such a model must specify how specific molecular processes contribute to neuronal function, how neurons contribute to network function, and how networks interact to produce behavior. This is a challenging undertaking, but some limited progress has been made in understanding the memory functions of the hippocampus with this degree of detail. There is increasing evidence that the hippocampus has a special role in the learning of sequences and the linkage of specific memories to context. In the first part of this paper, we review a model (the SOCRATIC model) that describes how the dentate and CA3 hippocampal regions could store and recall memory sequences in context. A major line of evidence for sequence recall is the "phase precession" of hippocampal place cells. In the second part of the paper, we review the evidence for theta-gamma phase coding. According to a framework that incorporates this form of coding, the phase precession is interpreted as cued recall of a discrete sequence of items from long-term memory. The third part of the paper deals with the issue of how the hippocampus could learn memory sequences. We show that if multiple items can be active within a theta cycle through the action of a short-term "buffer," NMDA-dependent plasticity can lead to the learning of sequences presented at realistic item separation intervals. The evidence for such a buffer function is reviewed. An important underlying issue is whether the hippocampal circuitry is configured differently for learning and recall. We argue that there are indeed separate states for learning and recall, but that both involve theta oscillations, albeit in possibly different forms. This raises the question of how neuromodulatory input might switch the hippocampus between learning and recall states and more generally how different neuromodulatory inputs reconfigure the hippocampus for different functions. In the fifth part of this paper we review our studies of dopamine and dopamine/NMDA interactions in the control of synaptic function. Our results show that dopamine dramatically reduces the direct cortical input to CA1 (the perforant path input), while having little effect on the input from CA3. In order to interpret the functional consequences of this pathway-specific modulation, it is necessary to understand the function of CA1 and the role of dopaminergic input from the ventral tegmental area (VTA). In the sixth part of this paper we consider several possibilities and address the issue of how dopamine hyperfunction or NMDA hypofunction, abnormalities that may underlie schizophrenia, might lead to the symptoms of the disease. Relevant to this issue is the demonstrated role of the hippocampus in novelty detection, a function that is likely to depend on sequence recall by the hippocampus. Novelty signals are generated when reality does not match ...

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“…The medial septum (MS) is an indispensable component of the theta-generating subcortical network (Lawson and Bland, 1993;Vertes and Kocsis, 1997). However, the hippocampo-septal backprojection has recently been proved to be crucial for synchronizing the medial septal and hippocampal circuits (Tó th et al, 1993;Wang, 2002).…”

Section: Introductionmentioning

confidence: 99%

GABAergic Neurons of the Medial Septum Lead the Hippocampal Network during Theta Activity

Hangya¹,

Borhegyi²,

Szilágyi³

et al. 2009

Journal of Neuroscience

275

265

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Information processing in the hippocampus critically relies on its reciprocal interaction with the medial septum (MS). Synchronization of the septo-hippocampal system was demonstrated during both major hippocampal activity states, the regular theta rhythm and the large amplitude irregular activity. Previous experimental and modeling data suggest that the MS provides rhythmic drive to the hippocampus, and hippocampo-septal feedback synchronizes septal pacemaker units. However, this view has recently been questioned based on the possibility of intrahippocampal theta genesis. Previously, we identified putative pacemaker neurons expressing parvalbumin (PV) and/or the pacemaker hyperpolarization-activated and cyclic nucleotide-gated nonselective cation channel (HCN) in the MS. In this study, by analyzing the temporal relationship of activity between the PV/HCN-containing medial septal neurons and hippocampal local field potential, we aimed to uncover whether the sequence of events during theta formation supports the classic view of septal drive or the challenging theory of hippocampal pacing of theta. Importantly, by implementing a circular statistical method, a temporal lead of these septal neurons over the hippocampus was observed on the course of theta synchronization. Moreover, the activity of putative hippocampal interneurons also preceded hippocampal local field theta, but by a shorter time period compared with PV/HCN-containing septal neurons. Using the concept of mutual information, the action potential series of PV/HCN-containing neurons shared higher amount of information with hippocampal field oscillation than PV/HCN-immunonegative cells. Thus, a pacemaker neuron population of the MS leads hippocampal activity, presumably via the synchronization of hippocampal interneurons.

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The Role of the Septohippocampal Pathway in the Regulation of Hippocampal Field Activity and Behavior: Analysis by the Intraseptal Microinfusion of Carbachol, Atropine, and Procaine

Cited by 130 publications

References 0 publications

Evidence for Differential Control of Posterior Hypothalamic, Supramammillary, and Medial Mammillary Theta-Related Cellular Discharge by Ascending and Descending Pathways

Evidence for Differential Control of Posterior Hypothalamic, Supramammillary, and Medial Mammillary Theta-Related Cellular Discharge by Ascending and Descending Pathways

Storage, recall, and novelty detection of sequences by the hippocampus: Elaborating on the SOCRATIC model to account for normal and aberrant effects of dopamine

GABAergic Neurons of the Medial Septum Lead the Hippocampal Network during Theta Activity

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