Related Experiment Video
Updated: Jul 20, 2026
12:06
Transmission Electron Microscopy as the Visualization Technique for Analysis of Circadian Synaptic Plasticity in the Mouse Barrel Cortex
Published on: August 19, 2025
The circadian clock modulates core steps in long-term memory formation in Aplysia
Lisa C Lyons1, Maria Sol Collado, Omar Khabour
1Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204-5001, USA.
Summary
The circadian clock suppresses long-term memory formation in Aplysia at night by inhibiting molecular changes. This involves regulating key proteins like ApC/EBP and MAPK activation, impacting memory processes.
Area of Science:
- Neuroscience
- Chronobiology
- Molecular Biology
Background:
- The circadian clock influences learning and memory, but its molecular mechanisms are not fully understood.
- Long-term sensitization (LTS) in Aplysia is a model for long-term memory formation.
- Previous studies show memory formation is suppressed when Aplysia are trained at night.
Purpose of the Study:
- To investigate how the circadian clock modulates molecular processes underlying long-term memory formation in Aplysia.
- To analyze the circadian regulation of phosphorylated mitogen-activated protein kinase (P-MAPK) and Aplysia CCAAT/enhancer binding protein (ApC/EBP) during LTS.
Main Methods:
- Analysis of basal and LTS-induced P-MAPK and ApC/EBP levels in Aplysia pleural ganglia.
- Investigating the effects of training during subjective day versus night on molecular changes.
- Assessing the impact of 5-HT (serotonin) levels and treatment on LTS.
Main Results:
- No basal circadian regulation of P-MAPK or total MAPK was observed.
- Basal ApC/EBP protein levels peaked at night, inversely correlating with LTS.
- LTS training during the subjective day induced greater increases in P-MAPK and ApC/EBP compared to night training.
- Circadian clock actively suppresses MAPK activation and transcription at night.
- 5-HT release and downstream effects on LTS are also modulated by the circadian clock.
Conclusions:
- The circadian clock modulates long-term memory formation in Aplysia at multiple molecular levels.
- Circadian regulation occurs through suppression of key protein changes (P-MAPK, ApC/EBP) and MAPK activation at night.
- Both 5-HT release and the response to 5-HT are under circadian control, affecting memory consolidation.
Related Concept Videos
02:19Circadian Rhythms and Gene Regulation
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
02:19Circadian Rhythms and Gene Regulation
The biological clock is involved in many aspects of regulating complex physiology in all animals. It was in 1935 when German zoologists, Hans Kalmus and Erwin Bünning, discovered the existence of circadian rhythm in Drosophila melanogaster. However, the internal molecular mechanisms behind the circadian clock remained a mystery until 1984, when Jeffrey C. Hall, Michael Rosbash, and Michael W. Young discovered the expression of the Per gene oscillating over a 24-hour cycle. In subsequent years,...
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
01:18Long-Term Memory
Long-term memory is a relatively permanent type of memory, capable of storing vast amounts of information over extended periods. Its storage capacity is generally considered unlimited.
Long-term memory can be categorized into two primary types: explicit and implicit memory. Explicit memory, also known as declarative memory, involves the conscious recollection of information that we deliberately try to remember, recall, and articulate. This type of memory encompasses specific facts, events, and...
Long-term memory can be categorized into two primary types: explicit and implicit memory. Explicit memory, also known as declarative memory, involves the conscious recollection of information that we deliberately try to remember, recall, and articulate. This type of memory encompasses specific facts, events, and...
01:35Long-term Potentiation
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre- and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
01:25Long-term Potentiation
Long-term potentiation, or LTP, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTP is the process of synaptic strengthening that occurs over time between pre and postsynaptic neuronal connections. The synaptic strengthening of LTP works in opposition to the synaptic weakening of long-term depression (LTD) and together are the main mechanisms that underlie learning and memory.
Hebbian LTP
LTP can occur when presynaptic neurons...
Hebbian LTP
LTP can occur when presynaptic neurons...