scholarly journals Neurotransmission and neuromodulation systems in the learning and memory network of Octopus vulgaris

2021 ◽  
Author(s):  
Naama Stern-mentch ◽  
Gabrielle Winters Carrington ◽  
Michael Belenky ◽  
Leonid L. Moroz ◽  
Binyamin Hochner
Keyword(s):  
Learning And Memory ◽  
Long Term Potentiation ◽  
Octopus Vulgaris ◽  
Connectivity Matrix ◽  
Term Potentiation ◽  
Memory Network ◽  
Short And Long Term ◽  
Deep Nucleus ◽  
Efficient Learning

The vertical lobe (VL) in the octopus brain plays an essential role in its sophisticated learning and memory. Early anatomical studies suggested that the VL is organized in a fan-out fan-in connectivity matrix comprising only three morphologically identified neuron types; input axons from the superior frontal lobe (SFL) innervating en passant millions of small amacrine interneurons (AMs) which converge sharply onto large VL output neurons (LNs). Recent physiological studies confirmed the feedforward excitatory connectivity: a glutamatergic synapse at the first SFL-to-AM synaptic layer and a cholinergic AM-to-LNs synapse. SFL-to-AMs synapses show a robust hippocampal-like activity-dependent long-term potentiation (LTP) of transmitter release. 5-HT, octopamine, dopamine and nitric oxide modulate short- and long-term VL synaptic plasticity. Here we present a comprehensive histolabeling study to better characterize the neural elements in the VL. We generally confirmed glutamatergic SFLs and cholinergic AMs. Intense labeling for NOS activity in the AMs neurites fitted with the NO-dependent presynaptic LTP mechanism at the SFL-to-AM synapse. New discoveries here reveal more heterogeneity of the VL neurons than previously thought. GABAergic AMs suggest a subpopulation of inhibitory interneurons in the first input layer. Clear GABA labeling in the cell bodies of LNs supported an inhibitory VL output yet the LNs co-expressed FMRFamide-like neuropeptides suggesting an additional neuromodulatory role of the VL output. Furthermore, a group of LNs was glutamatergic. A new cluster of cells organized in a deep nucleus showed rich catecholaminergic labeling and may play a role in intrinsic neuromodulation. In situ hybridization and immunolabeling allowed characterization and localization of a rich array of neuropeptides and neuromodulatores, likely involved in reward/punishment signals. This analysis of the fast transmission system, together with the newly found cellular elements helps integrate behavioral, physiological, pharmacological and connectome findings into a more comprehensive understanding of an efficient learning and memory network

scholarly journals Endocannabinoid dynamics gate spike-timing dependent depression and potentiation

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Yihui Cui ◽  
Ilya Prokin ◽  
Hao Xu ◽  
Bruno Delord ◽  
Stephane Genet ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Long Term Potentiation ◽  
Cellular Mechanism ◽  
Spike Timing ◽  
Long Term Depression ◽  
Term Potentiation ◽  
Short And Long Term

Synaptic plasticity is a cardinal cellular mechanism for learning and memory. The endocannabinoid (eCB) system has emerged as a pivotal pathway for synaptic plasticity because of its widely characterized ability to depress synaptic transmission on short- and long-term scales. Recent reports indicate that eCBs also mediate potentiation of the synapse. However, it is not known how eCB signaling may support bidirectionality. Here, we combined electrophysiology experiments with mathematical modeling to question the mechanisms of eCB bidirectionality in spike-timing dependent plasticity (STDP) at corticostriatal synapses. We demonstrate that STDP outcome is controlled by eCB levels and dynamics: prolonged and moderate levels of eCB lead to eCB-mediated long-term depression (eCB-tLTD) while short and large eCB transients produce eCB-mediated long-term potentiation (eCB-tLTP). Moreover, we show that eCB-tLTD requires active calcineurin whereas eCB-tLTP necessitates the activity of presynaptic PKA. Therefore, just like glutamate or GABA, eCB form a bidirectional system to encode learning and memory.

Arousing the LTP and learning debate

1997 ◽  
Vol 20 (4) ◽  
pp. 622-623 ◽  
Author(s):  
Stephen Maren
Keyword(s):  
Learning And Memory ◽  
Long Term Potentiation ◽  
Term Potentiation ◽  
Arousal Mechanism

Shors & Matzel provide compelling arguments against a role for hippocampal long-term potentiation (LTP) in mammalian learning and memory. As an alternative, they suggest that LTP is an arousal mechanism. I will argue that this view is not a satisfactory alternative to current conceptions of LTP function.

Dopamine D-1/D-5 Receptor Activation Is Required for Long-Term Potentiation in the Rat Neostriatum In Vitro

2001 ◽  
Vol 85 (1) ◽  
pp. 117-124 ◽  
Author(s):  
J.N.D. Kerr ◽  
J. R. Wickens
Keyword(s):  
Receptor Antagonist ◽  
Learning And Memory ◽  
Sch 23390 ◽  
Long Term Potentiation ◽  
Receptor Activation ◽  
Striatal Neurons ◽  
Theoretical Understanding ◽  
Endogenous Dopamine ◽  
Term Potentiation

Dopamine and glutamate are key neurotransmitters involved in learning and memory mechanisms of the brain. These two neurotransmitter systems converge on nerve cells in the neostriatum. Dopamine modulation of activity-dependent plasticity at glutamatergic corticostriatal synapses has been proposed as a cellular mechanism for learning in the neostriatum. The present research investigated the role of specific subtypes of dopamine receptors in long-term potentiation (LTP) in the corticostriatal pathway, using intracellular recording from striatal neurons in a corticostriatal slice preparation. In agreement with previous reports, LTP could be induced reliably under Mg2+-free conditions. This Mg2+-free LTP was blocked by dopamine depletion and by the dopamine D-1/D-5 receptor antagonist SCH 23390 but was not blocked by the dopamine D-2 receptor antagonist remoxipride or the GABAA antagonist picrotoxin. In dopamine-depleted slices, the ability to induce LTP could be restored by bath application of the dopamine D-1/D-5 receptor agonist, SKF 38393. These results show that activation of dopamine D-1/D-5 receptors by either endogenous dopamine or exogenous dopamine agonists is a requirement for the induction of LTP in the corticostriatal pathway. These findings have significance for current understanding of learning and memory mechanisms of the neostriatum and for theoretical understanding of the mechanism of action of drugs used in the treatment of psychotic illnesses and Parkinson's disease.

Nicotine-induced impairments of spatial cognition and long-term potentiation in adolescent male rats

2013 ◽  
Vol 33 (2) ◽  
pp. 203-213 ◽  
Author(s):  
G Han ◽  
L An ◽  
B Yang ◽  
L Si ◽  
T Zhang
Keyword(s):  
Young Adult ◽  
Learning And Memory ◽  
Long Term Potentiation ◽  
Male Rats ◽  
Adolescent Male ◽  
Control Group ◽  
Adult Offspring ◽  
Behavioral Impairment ◽  
Term Potentiation

The aim of the present study was to investigate whether cognitive behavioral impairment, induced by nicotine in offspring rats, was associated with the alteration of hippocampal short-term potentiation (STP) and long-term potentiation (LTP) and to discuss the potential underlying mechanism. Young adult offspring rats were randomly divided into three groups. The groups include: control group (CC), nicotine group 1 (NC), in which their mothers received nicotine from gestational day 3 (GD3) to GD18, and nicotine group 2 (CN), in which young adult offspring rats received nicotine from postnatal day 42 (PD42) to PD56. Morris water maze (MWM) test was performed and then field excitatory postsynaptic potentials elicited by the stimulation of perforant pathway were recorded in the hippocampal dentate gyrus region. The results of the MWM test showed that learning and memory were impaired by either prenatal or postnatal nicotine exposure. In addition, it was found that there was no statistical difference of the MWM data between both nicotine treatments. In the electrophysiological test, LTP and STP were significantly inhibited in both NC and CN groups in comparison with the CC group. Notably, STP in CN group was also lower than that in the NC group. These findings suggested that both prenatal and postnatal exposure to nicotine induced learning and memory deficits, while the potential mechanism might be different from each other due to their dissimilar impairments of synaptic plasticity.

Hippocampal Synaptic Stability and Plasticity

2020 ◽  
pp. 83-95
Author(s):  
Gabriele M. Rune
Keyword(s):  
Embryonic Development ◽  
Learning And Memory ◽  
Brain Region ◽  
Long Term Potentiation ◽  
Synaptic Potentiation ◽  
Term Potentiation ◽  
Synapse Density ◽  
Hippocampal Cultures ◽  
Estradiol Synthesis

Estradiol synthesis depends on the activity of aromatase, the enzyme that specifically and irreversibly converts testosterone to estradiol in steroidogenesis. Aromatase is expressed and is active in the hippocampus, a brain region related to learning and memory. Dynamics of spines and spine synapses, including expression of presynaptic and postsynaptic proteins, are controlled by hippocampus-derived estradiol in female rodents, but not in male rodents. This also holds true for long-term potentiation. Inhibition of aromatase, either pharmacologically or by genetic approaches, results in a decrease in synapse density and synaptic potentiation in female animals and in neonatal hippocampal cultures that originate from females. The consistency of the findings in rodents and in perinatal primary hippocampal cultures points to sex-specific differentiation processes during embryonic development, which underlie sex-dependent differences in neurosteroid action in the hippocampus.

Sign in / Sign up

Export Citation Format

Share Document