The Septal Complex as Seen Through the Context of Fear

Sparks, Peter D.; LeDoux, Joseph E.

doi:10.1007/978-1-4612-1302-4_10

Cited by 8 publications

(7 citation statements)

References 140 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…from subiculum). Taken together with ¢ndings that the lateral septal nuclei contribute to working and reference memory (M'Harzi and Jarrard, 1992;Leutgeb and Mizumori, 1999) and contextual fear conditioning (Garcia et al, 1997;Vouimba et al, 1998Vouimba et al, , 1999Sparks and LeDoux, 2000), these coding properties suggest that the lateral septum could be an e¡ective output pathway from hippocampus, in particular for providing information about the current context.…”

Section: Discussionmentioning

confidence: 78%

Context-specific spatial representations by lateral septal cells

Leutgeb

Mizumori

2002

Neuroscience

View full text Add to dashboard Cite

AbstractöTo test whether the location coding of lateral septal cells is dependent on cue constellations, we examined single units in two di¡erent recording arenas on alternating days. Repeated recordings of lateral septal neurons in the same arena revealed that matching locations are encoded on separate days by about one third of the cells. The cells typically showed location-selective ¢ring in only one of the two recording arenas and initially showed unrelated patterns when tested in a di¡erent recording arena. When tested for a second time in each recording arena, the initially dissimilar patterns were modi¢ed towards increased similarity between arenas. Simultaneously recorded hippocampal principal cells showed distinct place ¢elds for each recording arena throughout the recording sequence. These results indicate that the initial reorganization of the lateral septal location coding may occur as a direct consequence of the hippocampal reorganization. Further septal reorganization is then partially independent of established place ¢elds in the CA1 and CA3 area.Location-selective cells in cortical areas that receive projections from hippocampus proper (i.e. the subiculum and the entorhinal cortex) have not been shown to encode di¡erences between recording arenas. Although some characteristics of this generalized coding scheme have also been found for location-selective lateral septal cells, the encoding of context information was generally preserved in the subcortical target cells of projections from the CA1 and CA3 area. ß 2002 IBRO. Published by Elsevier Science Ltd. All rights reserved.Key words: septum, hippocampus, place ¢elds, remapping.Allocentric space is encoded by the ¢ring rate of neurons in multiple subregions of the hippocampal formation including the CA1 area, the CA3 area, the dentate gyrus, the subiculum, and the entorhinal cortex (O'Keefe, 1976;Barnes et al., 1990;Mizumori et al., 1992;Quirk et al., 1992;Sharp and Green, 1994). Neurons in these subregions show localized increases in ¢ring rates when a rodent occupies the section of the arena £oor that is referred to as the place ¢eld. The size of the ¢elds and their peak ¢ring rates above baseline levels show pronounced variability for di¡erent cells within and, in particular, between di¡erent hippocampal subregions. In addition to variability for the same recording arena, cells in the hippocampal formation also show a spectrum of responses when tested in a second recording arena.The most common changes that are seen for cells in the CA1 and CA3 area in a modi¢ed arena are increased or decreased background ¢ring rates in addition to altered spatial ¢ring patterns such as the onset, o¡set, and shift of location-speci¢c neuronal activity (Hill, 1978;Kubie and Ranck, 1983;Muller and Kubie, 1987;Thompson and Best, 1989;Wilson and McNaughton, 1993). If shifted, the altered ¢ring patterns are typically not related to each other by a rotation or translation (Kubie and Ranck, 1983;Muller and Kubie, 1987;Bostock et al., 1991;Quirk et al., 1992;Tanila et ...

show abstract

Section: Discussionmentioning

confidence: 78%

Context-specific spatial representations by lateral septal cells

Leutgeb

Mizumori

2002

Neuroscience

View full text Add to dashboard Cite

show abstract

“…So far, the septum had been shown to be involved in fear conditioning (Gray and McNaughton 1983;Sparks and LeDoux 2000), yet previous studies had not provided direct evidence for distinct roles of the LS and MS in elemental and contextual fear conditioning. This is probably because most of the septal damage or inactivation extended to the whole septum and also because analysis was restricted to either cue or contextual conditioning.…”

Section: Discussionmentioning

confidence: 99%

Dissociated roles for the lateral and medial septum in elemental and contextual fear conditioning

Calandreau¹,

Jaffard²,

Desmedt³

2007

Learn. Mem.

View full text Add to dashboard Cite

Extensive evidence indicates that the septum plays a predominant role in fear learning, yet the direction of this control is still a matter of debate. Increasing data suggest that the medial (MS) and lateral septum (LS) would be differentially required in fear conditioning depending on whether a discrete conditional stimulus (CS) predicts, or not, the occurrence of an aversive unconditional stimulus (US). Here, using a tone CS-US pairing (predictive discrete CS, context in background) or unpairing (context in foreground) conditioning procedure, we show, in mice, that pretraining inactivation of the LS totally disrupted tone fear conditioning, which, otherwise, was spared by inactivation of the MS. Inactivating the LS also reduced foreground contextual fear conditioning, while sparing the higher level of conditioned freezing to the foreground (CS-US unpairing) than to the background context (CS-US pairing). In contrast, inactivation of the MS totally abolished this training-dependent level of contextual freezing. Interestingly, inactivation of the MS enhanced background contextual conditioning under the pairing condition, whereas it reduced foreground contextual conditioning under the unpairing condition. Hence, the present findings reveal a functional dissociation between the LS and the MS in Pavlovian fear conditioning depending on the predictive value of the discrete CS. While the requirement of the LS is crucial for the appropriate processing of the tone CS-US association, the MS is crucial for an appropriate processing of contextual cues as foreground or background information.Extensive evidence has implicated the septum in fear and anxiety. On the one hand, previous studies have shown that damage to the septum could result in anxiolytic-like behavioral effects McNaughton 1983, 2000). In this context, Gray (1982) proposed a model according to which activity of the septalhippocampal complex reflects a state of "anxiety" produced when there is a mismatch between predicted and actual sensory events. By preventing animals from detecting such a change, lesions or inactivation of the septum would then cause a decrease in fear or anxiety. On the other hand, septal lesions were also found to profoundly increase fear and anxiety-related behaviors (Thomas 1988), producing the "septal rage syndrome" in many species (Brady and Nauta 1953). This syndrome would result from a generalized disinhibition of fear leading to exacerbated defensive reactions. Hence, a long history of lesion studies indicates that the septum plays a predominant role in fear learning, yet the direction of this control is still a matter of debate.The septal complex is anatomically heterogeneous. While the lateral septum (LS) receives a massive glutamatergic fiber input from the hippocampus by the fornix pathway, the medial septum (MS) sends impressive cholinergic and GABAergic projections to the hippocampus (Jakab and Leranth 1995; Swanson and Risold 2000).Functionally, the MS has been shown to be critically involved in regulating some physiologica...

show abstract

“…Reversible inactivation of the LS yielded similar phenotypes (Albert and Richmond, 1976; Albert and Wong, 1978). These and other data have led to a prevailing view that LS output is anxiolytic, i.e., dampens fear or anxiety (reviewed in (Sparks and LeDoux, 2000; Sheehan et al, 2004)).…”

Section: Introductionmentioning

confidence: 99%

Control of Stress-Induced Persistent Anxiety by an Extra-Amygdala Septohypothalamic Circuit

Anthony

Dee

Bernard

et al. 2014

Cell

228

255

View full text Add to dashboard Cite

The extended amygdala has dominated research on the neural circuitry of fear and anxiety, but the septo-hippocampal axis plays an important role as well. The lateral septum (LS) is thought to suppress fear and anxiety, through its outputs to the hypothalamus. However, this structure has not yet been dissected using modern tools. The type 2 CRF receptor (Crfr2) marks a subset of LS neurons, whose functional connectivity we have investigated using optogenetics. Crfr2+ cells include GABAergic projection neurons that connect with the anterior hypothalamus. Surprisingly, we find that these LS outputs enhance stress-induced behavioral measures of anxiety. Furthermore, transient activation of Crfr2+ neurons promotes, while inhibition suppresses, persistent anxious behaviors. LS Crfr2+ outputs also positively regulate circulating corticosteroid levels. These data identify a subset of LS projection neurons that promote, rather than suppress, stress-induced behavioral and endocrinological dimensions of persistent anxiety states, and provide a cellular point-of-entry to LS circuitry.

show abstract

The Septal Complex as Seen Through the Context of Fear

Cited by 8 publications

References 140 publications

Context-specific spatial representations by lateral septal cells

Context-specific spatial representations by lateral septal cells

Dissociated roles for the lateral and medial septum in elemental and contextual fear conditioning

Control of Stress-Induced Persistent Anxiety by an Extra-Amygdala Septohypothalamic Circuit

Contact Info

Product

Resources

About