The Fimbria-Fornix/Cingular Bundle Pathways: A Review of Neurochemical and Behavioural Approaches Using Lesions and Transplantation Techniques

Cassel, Jean‐Christophe; Duconseille, Elee; Jeltsch, Hélène; Will, Bruno

doi:10.1016/s0301-0082(97)00009-9

Cited by 104 publications

(82 citation statements)

References 428 publications

(443 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, implants of AChsecreting fibroblasts into the hippocampus attenuate cognitive deficits produced by unilateral fimbria-fornix lesions; implants into the frontal or parietal cortex are ineffective (DickinsonAnson et al 1998). Similarly, hippocampal grafts of fetal neuronal tissue rich in cholinergic neurons reverse memory deficits produced by a variety of manipulations, including septal lesions, hippocampal lesions, bilateral fimbria-fornix lesions, or selective 192 IgG-saporin-induced lesions of the septohippocampal ACh projection (Tarricone et al 1996;Cassel et al 1997Cassel et al , 2002. Behavioral improvement is correlated with recovery of cholinergic markers Daniloff et al 1985;Tarricone et al 1991Tarricone et al , 1993 and prevented by systemic administration of cholinergic antagonists (Nilsson et al 1987;Li et al 1992).…”

Section: Upregulation Of Hippocampal Ach Reverses Septal Memory Deficitsmentioning

confidence: 96%

Septohippocampal Acetylcholine: Involved in but not Necessary for Learning and Memory?

Parent¹,

Baxter²

2004

Learn. Mem.

175

132

View full text Add to dashboard Cite

The neurotransmitter acetylcholine (ACh) has been accorded an important role in supporting learning and memory processes in the hippocampus. Cholinergic activity in the hippocampus is correlated with memory, and restoration of ACh in the hippocampus after disruption of the septohippocampal pathway is sufficient to rescue memory. However, selective ablation of cholinergic septohippocampal projections is largely without effect on hippocampal-dependent learning and memory processes. We consider the evidence underlying each of these statements, and the contradictions they pose for understanding the functional role of hippocampal ACh in memory. We suggest that although hippocampal ACh is involved in memory in the intact brain, it is not necessary for many aspects of hippocampal memory function.The goal of this review is to consider the role of septohippocampal acetylcholine (ACh) in learning and memory processes. The evidence in this regard falls broadly into two different classes. On the one hand, considerable data implicate septohippocampal ACh in memory function. This system is engaged during memory processing, indexed by ACh release or by modification of cholinergic markers, and manipulations that affect memory produce parallel changes in hippocampal cholinergic activity. Furthermore, agents that increase hippocampal cholinergic function are sufficient to reverse memory impairments caused by disruption of the septohippocampal system. However, data from studies of selective lesions of septohippocampal cholinergic neurons with the immunotoxin 192 IgG-saporin call into question the essential role of this system in learning and memory, because these studies generally failed to find severe impairments in memory function. Our goal in this article is to review the data underlying each of these lines of evidence, and to attempt to reconcile these apparently disparate observations.The discrepancy between these lines of evidence might imply that septohippocampal ACh is involved in memory processing, but is not necessary for it to occur. This viewpoint would allow for correlated changes in ACh release and memory, and for the ability of cholinergic agents to reverse memory impairments caused by disruption of septohippocampal function. However, it also would permit memory to proceed relatively normally in the absence of septohippocampal cholinergic input. By describing this viewpoint and its implications for the functional role of hippocampal ACh in memory, we seek to promote the idea that data from lesions are compatible with data from other experimental approaches. Furthermore, we suggest that a convergent approach that incorporates observations from different experimental methods will reveal functional characteristics of hippocampal ACh that would not be apparent from studies using a single strategy.Before discussing the role of this system in cognition, a brief review of its anatomical and neurochemical organization is warranted. The septum is connected to the hippocampus via the fimbria-fornix, which carries projections ...

show abstract

Section: Upregulation Of Hippocampal Ach Reverses Septal Memory Deficitsmentioning

confidence: 96%

Septohippocampal Acetylcholine: Involved in but not Necessary for Learning and Memory?

Parent¹,

Baxter²

2004

Learn. Mem.

175

132

View full text Add to dashboard Cite

show abstract

“…The fornix provides bidirectional connectivity between the hippocampus and subcortical structures (Swanson and Cowan, 1977;Cassel et al, 1997). Fornix lesions reduce long-term potentiation (LTP) persistence in the dentate gyrus (Buzsaki and Gage, 1989;Nakao et al, 2001), impair hippocampus-dependent spatial learning, but spare hippocampus-independent cue-approach learning (Nilsson et al, 1987;Packard et al, 1989;Sutherland and Rodriguez, 1989;Sziklas and Petrides, 2002;Gaffan et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Fornix Lesions Decouple the Induction of Hippocampal Arc Transcription from Behavior But Not Plasticity

et al. 2006

View full text Add to dashboard Cite

The immediate-early gene (IEG) Arc is transcribed after behavioral and physiological treatments that induce synaptic plasticity and is implicated in memory consolidation. The relative contributions of neuronal activity and learning-related plasticity to the behavioral induction of Arc remain to be defined. To differentiate the contributions of each, we assessed the induction of Arc transcription in rats with fornix lesions that impair hippocampal learning yet leave cortical connectivity and neuronal firing essentially intact. Arc expression was assessed after exploration of novel environments and performance of a novel water maze task during which normal rats learned the spatial location of an escape platform. During the same task, rats with fornix lesions learned to approach a visible platform but did not learn its spatial location. Rats with fornix lesions had normal baseline levels of hippocampal Arc mRNA, but unlike normal rats, expression was not increased in response to water maze training. The integrity of signaling pathways controlling Arc expression was demonstrated by stimulation of the medial perforant path, which induced normal synaptic potentiation and Arc in rats with fornix lesions. Together, the results demonstrate that Arc induction can be decoupled from behavior and is more likely to indicate the engagement of synaptic plasticity mechanisms than synaptic or neuronal activity per se. The results further imply that fornix lesions may impair memory in part by decoupling neuronal activity from signaling pathways required for long-lasting hippocampal synaptic plasticity.

show abstract

“…Cognitive deficits following FF lesions are believed to result from a lack of cholinergic innervation from the medial septum (Cassel et al, 1997). Thus, another possibility is that the LTP impairment after FF lesions is due to a decrease in cholinergic terminals at MPP-DG synapses.…”

Section: Discussionmentioning

confidence: 99%

“…The fimbria-fornix (FF), one of the principal fiber tracts in the central nervous system, reciprocally connects the hippocampus with the subcortical and cortical areas (Cassel et al, 1997). Lesions of the bilateral FF are known to produce profound impairments of spatial performance in a variety of maze tasks (Cassel et al, 1998;Hannesson and Skelton, 1998).…”

Section: Introductionmentioning

confidence: 99%

Fimbrial control of bidirectional synaptic plasticity of medial perforant path‐dentate transmission

Nakao

Ikegaya

Yamada

et al. 2002

Synapse

View full text Add to dashboard Cite

Lesions of the fimbria-fornix (FF) tract cause profound impairments of cognitive ability in animals. Our previous study showed that spatial performance correlates with long-term potentiation (LTP) of the dentate gyrus (DG), but not of the CA1 region, in rats with bilateral FF lesions, suggesting that FF lesions selectively inhibited LTP in the DG. The cortical input to the DG is anatomically and physiologically divided into two types of afferents, i.e., the medial perforant path (MPP) and the lateral perforant path (LPP), which show distinct synaptic properties. To elucidate the difference in the FF modulation of these two inputs, field responses were recorded from MPPor LPP-DG synapses in anesthetized rats. MPP-DG synapses of rats with FF lesions displayed neither LTP in response to theta-burst stimulation nor long-term depression (LTD) in response to low-frequency burst stimulation. In contrast to the MPP, LPP-DG synapses showed normal LTP in rats with FF lesions. The low-frequency burst stimulation could not induce LTD at LPP-DG synapses in either intact or FF-lesioned rats. These results suggest that the FF pathway selectively supports the mechanisms of bidirectional synaptic plasticity at MPP-DG synapses. This study provides new insights into external control of information processing in the hippocampus.

show abstract

The Fimbria-Fornix/Cingular Bundle Pathways: A Review of Neurochemical and Behavioural Approaches Using Lesions and Transplantation Techniques

Cited by 104 publications

References 428 publications

Septohippocampal Acetylcholine: Involved in but not Necessary for Learning and Memory?

Septohippocampal Acetylcholine: Involved in but not Necessary for Learning and Memory?

Fornix Lesions Decouple the Induction of Hippocampal Arc Transcription from Behavior But Not Plasticity

Fimbrial control of bidirectional synaptic plasticity of medial perforant path‐dentate transmission

Contact Info

Product

Resources

About