Structural changes and the storage of long-term memory in Aplysia

1999 ◽  
Vol 77 (9) ◽  
pp. 738-747 ◽  
Author(s):  
Craig H Bailey
Keyword(s):  
Motor Neurons ◽  
Structural Changes ◽  
Long Term Memory ◽  
Synaptic Growth ◽  
Term Memory ◽  
Molecular Logic ◽  
Dissociated Cell Culture ◽  
Synaptic Circuitry ◽  
Activity Dependent

Long-term memory for sensitization of the gill-withdrawal reflex inAplysia is associated with the growth of new synaptic connections between sensory and motor neurons. The duration of this structural change parallels the behavioral retention of the memory. Such changes can be reconstituted in dissociated cell culture by repeated presentations of the modulatory neurotransmitter serotonin (5HT) and are associated with an activity-dependent downregulation of NCAM-related cell adhesion molecules thought to contribute to cell recognition and axonal outgrowth during development. Thus, aspects of the mechanisms utilized for learning-related synaptic growth initiated by experience in the adult may eventually be understood in the context of the molecular logic that shapes synaptic circuitry during the later stages of neuronal development.Key words: learning, synapse, invertebrate, habituation, sensitization.

scholarly journals Long-term sensitization training in Aplysia leads to an increase in the expression of BiP, the major protein chaperon of the ER.

1992 ◽  
Vol 119 (5) ◽  
pp. 1069-1076 ◽  
Author(s):  
D Kuhl ◽  
T E Kennedy ◽  
A Barzilai ◽  
E R Kandel
Keyword(s):  
Protein Synthesis ◽  
Motor Neurons ◽  
Structural Changes ◽  
State Level ◽  
Long Term Memory ◽  
Major Protein ◽  
Synaptic Connections ◽  
Term Memory ◽  
Long Term Facilitation

Long-term memory for sensitization of the gill- and siphon-withdrawal reflexes in Aplysia californica requires RNA and protein synthesis. These long-term behavioral changes are accompanied by long-term facilitation of the synaptic connections between the gill and siphon sensory and motor neurons, which are similarly dependent on transcription and translation. In addition to showing an increase in over-all protein synthesis, long-term facilitation is associated with changes in the expression of specific early, intermediate, and late proteins, and with the growth of new synaptic connections between the sensory and motor neurons of the reflex. We previously focused on early proteins and have identified four proteins as members of the immunoglobulin family of cell adhesion molecules related to NCAM and fasciclin II. We have now cloned the cDNA corresponding to one of the late proteins, and identified it as the Aplysia homolog of BiP, an ER resident protein involved in the folding and assembly of secretory and membrane proteins. Behavioral training increases the steady-state level of BiP mRNA in the sensory neurons. The increase in the synthesis of BiP protein is first detected 3 h after the onset of facilitation, when the increase in overall protein synthesis reaches its peak and the formation of new synaptic terminals becomes apparent. These findings suggest that the chaperon function of BiP might serve to fold proteins and assemble protein complexes necessary for the structural changes characteristic of long-term memory.

scholarly journals Reinstatement of long-term memory following erasure of its behavioral and synaptic expression in Aplysia

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Shanping Chen ◽  
Diancai Cai ◽  
Kaycey Pearce ◽  
Philip Y-W Sun ◽  
Adam C Roberts ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Long Term Memory ◽  
Synaptic Connections ◽  
Synaptic Growth ◽  
Term Memory ◽  
Synaptic Structure ◽  
Synaptic Change ◽  
Long Term Facilitation ◽  
The Brain

Long-term memory (LTM) is believed to be stored in the brain as changes in synaptic connections. Here, we show that LTM storage and synaptic change can be dissociated. Cocultures of Aplysia sensory and motor neurons were trained with spaced pulses of serotonin, which induces long-term facilitation. Serotonin (5HT) triggered growth of new presynaptic varicosities, a synaptic mechanism of long-term sensitization. Following 5HT training, two antimnemonic treatments—reconsolidation blockade and inhibition of PKM—caused the number of presynaptic varicosities to revert to the original, pretraining value. Surprisingly, the final synaptic structure was not achieved by targeted retraction of the 5HT-induced varicosities but, rather, by an apparently arbitrary retraction of both 5HT-induced and original synapses. In addition, we find evidence that the LTM for sensitization persists covertly after its apparent elimination by the same antimnemonic treatments that erase learning-related synaptic growth. These results challenge the idea that stable synapses store long-term memories.

scholarly journals An Important Role of Neural Activity-Dependent CaMKIV Signaling in the Consolidation of Long-Term Memory

Cell ◽  
2001 ◽  
Vol 106 (6) ◽  
pp. 771-783 ◽  
Author(s):  
Hyejin Kang ◽  
Linus D. Sun ◽  
Coleen M. Atkins ◽  
Thomas R. Soderling ◽  
Matthew A. Wilson ◽  
...  
Keyword(s):  
Neural Activity ◽  
Long Term Memory ◽  
Term Memory ◽  
Activity Dependent
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