Modeling the Piriform Cortex

Hasselmo, Michael E.; Linster, Christiane

doi:10.1007/978-1-4615-4903-1_11

Cited by 5 publications

(7 citation statements)

References 99 publications

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“…This work continues previous work exploring the storage of patterns of activity in a network with separate populations of excitatory and inhibitory neurons (Hasselmo and Linster 1998b; Hasselmo et al , 1997. This model draws on the assumption that the excitatory recurrent connections of the piriform cortex mediate associative memory function, allowing storage of patterns of activity representing odors, and retrieval of these patterns given incomplete pattern cues (Bower 1995;Haberly 1985;Haberly and Bower 1989;Hasselmo and Linster 1998a;Wilson and Bower 1988). The distinct modeling of separate populations of excitatory and inhibitory neurons used in the model presented here allows detailed analysis of how modulation of inhibition could play a role in setting appropriate functional dynamics in associative memory networks.…”

Section: Implications Of the Modelsupporting

confidence: 56%

“…In this computational model of cortical memory function, individual odors are represented as different patterns of afferent input activating specific subpopulations of excitatory neurons (Hasselmo 1995;Hasselmo and Linster 1998a;. The afferent patterns representing individual odors are stored as self-sustained equilibrium states (attractor states) in the network, with a particular pattern of active neurons within the network.…”

Section: Computational Modelingmentioning

confidence: 99%

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Modulation of Inhibitory Synaptic Potentials in the Piriform Cortex

Patil

Hasselmo

1999

Journal of Neurophysiology

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Modulation of inhibitory synaptic potentials in the piriform cortex. Intracellular recordings from pyramidal neurons in brain slice preparations of the piriform cortex were used to test results from a computational model about the effects of cholinergic agonists on inhibitory synaptic potentials induced by stimulation of afferent fibers in layer Ia and association/intrinsic fibers in layer Ib. A simple model of piriform cortex as an associative memory was used to analyze how suppression of inhibitory synaptic transmission influenced performance of the network. Levels of suppression of excitatory synaptic transmission were set at levels determined in previous experimental work. Levels of suppression of inhibitory synaptic transmission were then systematically varied within the model. This modeling work demonstrated that suppression of inhibitory synaptic transmission in layer Ib should be stronger than suppression of inhibitory synaptic transmission in layer Ia to keep activity levels high enough for effective storage. Experimental data showed that perfusion of the cholinergic agonist carbachol caused a significant suppression of inhibitory postsynaptic potentials (IPSPs) in the pyramidal neurons that were induced by stimulation of layer Ib, with a weaker effect on IPSPs induced by stimulation of layer Ia. As previously described, carbachol also selectively suppressed excitatory postsynaptic potentials (EPSPs) elicited by intrinsic but not afferent fiber stimulation. The decrease in amplitude of IPSPs induced by layer Ib stimulation did not appear to be directly related to the decrease in EPSP amplitude induced by layer Ib stimulation. The stimulation necessary to induce neuronal firing with layer Ia stimulation was reduced in the presence of carbachol, whereas that necessary to induce neuronal firing with layer Ib stimulation was increased, despite the depolarization of resting membrane potential. Thus physiological data on cholinergic modulation of inhibitory synaptic potentials in the piriform cortex is compatible with the functional requirements determined from computational models of piriform cortex associative memory function.

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Section: Implications Of the Modelsupporting

confidence: 56%

Section: Computational Modelingmentioning

confidence: 99%

Modulation of Inhibitory Synaptic Potentials in the Piriform Cortex

Patil

Hasselmo

1999

Journal of Neurophysiology

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“…Awakenings from NREM sleep are more likely to be concerned with current issues. The lack of episodic memories in REM dreams goes along with experimental findings in the rat to be described shortly, which demonstrate that information does not flow from the hippocampus to the neocortex during REM sleep as it does during NREM sleep [ 24 , 28 , 30 , 31 ]. Suppression of REM sleep with antidepressant drugs and even its complete elimination with monoamine oxidase inhibitors does not reliably alleviate post-traumatic nightmares [ 1 ].…”

Section: Rem Vs Nremmentioning

confidence: 86%

“…The initial encoding of new memories during the waking exploratory state and their subsequent consolidation during sleep are modulated by acetylcholine [ 30 , 72 ]. A primary function of acetylcholine in the hippocampus is to reduce interference in the learning process by adaptively timing and separating memory encoding and retrieval.…”

Section: Acetylcholine: Encoding and Retrievalmentioning

confidence: 99%

“…The amount released reflects the novelty detected in the environment. During active wakefulness, high levels of acetylcholine in the hippocampus favor sensory processing and the predominant flow of information from the entorhinal cortex to the hippocampal CA3 region where the episodic representations of events are registered [ 30 ]. During active wakefulness, neurons in layers II and III of the entorhinal cortex convey multimodal information into the hippocampus but neuronal activity in the output layers V and VI of the entorhinal cortex is reduced [ 24 ].…”

Section: Acetylcholine: Encoding and Retrievalmentioning

confidence: 99%

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Nightmares and the Cannabinoids

Mamelak

2020

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: The cannabinoids, Δ9 tetrahydrocannabinol and its analogue, nabilone, have been found to reliably attenuate the intensity and frequency of post-traumatic nightmares. This essay examines how a traumatic event is captured in the mind after just a single exposure and repeatedly replicated during the nights that follow. The adaptive neurophysiological, endocrine and inflammatory changes that are triggered by the trauma and that alter personality and behavior are surveyed. These adaptive changes, once established, can be difficult to reverse. But cannabinoids, uniquely, have been shown to interfere with all of these post-traumatic somatic adaptations. While cannabinoids can suppress nightmares and other symptoms of the post-traumatic stress disorder, they are not a cure. There may be no cure. The cannabinoids may best be employed, alone, but more likely in conjunction with other agents, in the immediate aftermath of a trauma to mitigate or even abort the metabolic changes which are set in motion by the trauma and which may permanently alter the reactivity of the nervous system. Steps in this direction have already been taken.

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Selective loss of cholinergic neurons projecting to the olfactory system increases perceptual generalization between similar, but not dissimilar, odorants.

Linster¹,

Garcia²,

Hasselmo³

et al. 2001

Behavioral Neuroscience

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The neuromodulator acetylcholine is thought to modulate information processing in the olfactory system. The authors used 192 IgG-saporin, a lesioning agent selective for basal forebrain cholinergic neurons, to determine whether selective lesions of cholinergic neurons projecting to the olfactory bulb and cortex affect odor perception in rats. Lesioned and sham-operated rats were tested in an olfactory generalization paradigm with sets of chemically related odorants (n-aliphatic aldehydes, acids, and alcohols). Lesioned rats generalized more between chemically similar odorants but did not differ from controls in their response to chemically unrelated odorants or in acquisition of the conditioned odor. Results show that cholinergic inputs to the olfactory system influence perceptual qualities of odorants and confirm predictions made by computational models of this system.

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Modeling the Piriform Cortex

Cited by 5 publications

References 99 publications

Modulation of Inhibitory Synaptic Potentials in the Piriform Cortex

Modulation of Inhibitory Synaptic Potentials in the Piriform Cortex

Nightmares and the Cannabinoids

Selective loss of cholinergic neurons projecting to the olfactory system increases perceptual generalization between similar, but not dissimilar, odorants.

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