New research on octopuses sheds light on memory

Jun 17, 2008
Octopus Memory Training
The octopus learns to avoid attacking a red ball because he gets a mild electric shock. Credit: Hebrew University photo

Research on octopuses has shed new light on how our brains store and recall memory, says Dr. Benny Hochner of the Department of Neurobiology at the Alexander Silberman Institute of Life Sciences at the Hebrew University of Jerusalem. Why octopuses?

Octopuses and other related creatures, known as cephalopods, are considered to be the most intelligent invertebrates because they have relatively large brains and they can be trained for various learning and memory tasks, says Dr. Hochner.

Their behavior repertoire and learning and memory abilities are even comparable in their complexity to those of advanced vertebrates. However, they are still invertebrate mollusks with brains that contain a much fewer number of nerve cells and much simpler anatomical organization than that of vertebrate brains. This unique constellation was utilized to tackle one of the most interesting questions in modern neuroscience, which is how the brain stores and recalls memories

In a previous study, Hochner discovered that an area in the octopus brain that was known to be important for learning and memory showed a robust, activity-dependent, long-term synaptic potentiation (LTP) – a process which is strikingly similar to that discovered in vertebrate brains.

This LTP process accelerates the transformation of information between nerve cells by enhancing the transmission of electrical signals through a special structure called the synapse for days and even a lifetime. It is believed that in the area in the brain that stores memories, the synaptic connections between nerve cells that are more active during a specific learning function are strengthened by this activity-induced LTP. One can describe this process as an "engraving of memory traces" in the neuronal networks that store information for a long time, says Hochner.

In a recent article in the journal, Current Biology, Hochner described how he tested these hypotheses and ideas in the brain of the octopus. He blocked the ability of the brain to use LTP during learning by utilizing artificial LTP and though electrical stimulation.

When LTP was blocked with this technique shortly before training for a specific task, the experimental group of octopuses did not remember well the task when tested for long-term memory the day after training. Similar results were obtained when sensory information was prevented from getting into the learning and memory area by lesioning a specific connection in the brain. These findings therefore support the finding that LTP is indeed important for creating memories.

The fact that this was revealed in an invertebrate suggests that this process (LTP) is an efficient mechanism for mediation of learning and memory. The research results in the octopuses also shed new light on how memory systems are organized. Even if one accepts that LTP is important for learning and memory, however, Hochner stresses that further research will be required to understand how this cellular process is utilized in other animal or human brains for storing memories and how these memories are recollected.

The results can also have implications with respect to the organization of learning and memory systems, says Hochner. It is documented that memory processes can be divided into a short-term memory of minutes or a few hours and long-term memory that can store important events and facts for days or even our entire lifetime. Interestingly, notes Hochner, his results show that as in mammals, including humans, the short and long-term memory in the octopus are segregated into two separate systems, each in different locations in the brain.

It is not completely understood how these two systems are interconnected, if at all. However, the organization in the octopus demonstrates a sophistication that was not described yet in other animals. In the octopus, the short-term and long-term systems are working in parallel, but not independently. This is so because the long-term memory area -- in addition to its capacity to store long-term memories -- also regulates the rate at which the short-term memory system acquires short-term memories. This regulatory mechanism is probably useful in cases where faster learning is significant for the octopus' survival in emergency or risky situations.

Source: The Hebrew University of Jerusalem

Explore further: Fungus deadly to AIDS patients found to grow on trees

add to favorites email to friend print save as pdf

Related Stories

The Mechanisms of Memory

Mar 09, 2010

(PhysOrg.com) -- USC College's Michel Baudry and graduate student Sohila Zadran brought forty years of research to a pinnacle with their breakthroughs in the science of learning and memory.

To make memories, new neurons must erase older ones

Nov 12, 2009

Short-term memory may depend in a surprising way on the ability of newly formed neurons to erase older connections. That's the conclusion of a report in the November 13th issue of the journal Cell that provid ...

Recommended for you

Researchers look at small RNA pathways in maize tassels

1 hour ago

Researchers at the University of Delaware and other institutions across the country have been awarded a four-year, $6.5 million National Science Foundation grant to analyze developmental events in maize anthers ...

How plant cell compartments change with cell growth

2 hours ago

A research team led by Kiminori Toyooka from the RIKEN Center for Sustainable Resource Science has developed a sophisticated microscopy technique that for the first time captures the detailed movement of ...

Plants can 'switch off' virus DNA

2 hours ago

A team of virologists and plant geneticists at Wageningen UR has demonstrated that when tomato plants contain Ty-1 resistance to the important Tomato yellow leaf curl virus (TYLCV), parts of the virus DNA ...

A better understanding of cell to cell communication

3 hours ago

Researchers of the ISREC Institute at the School of Life Sciences, EPFL, have deciphered the mechanism whereby some microRNAs are retained in the cell while others are secreted and delivered to neighboring ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Mercury_01
4 / 5 (2) Jun 17, 2008
The article Doesnt go very far to expand our knowlege of memory. I think we should find a way to test the "holographic memory" hypothesis. It seems like the best way to explain our memory. In this view, sensory signals are printed on certain areas of the brain, though not confined to any specific area. The input is first run through a sort of natural algorithm,as in a fourier transform, and can only be retrieved when the proper decoding algorithm is used. this axiom goes a long way to explain how so much information is mixed together in the brain, and why people can still have memory even after a full lobotomy. As in a hologram, every piece of the media contains all the information to recreate the whole picture. Thats why we cant pinpoint areas where memories are held.
HenisDov
not rated yet Jun 18, 2008
Shedding Light On Memory Mechanism

Two additional, recent works, locate again the sites in multicell organisms where memories are impressed:

http://www.bristo...279.html

http://www.physor...831.html

But the mechanism of memory impression and recall has not yet been brought to light.

Several years ago I suggested in "Memory, Sentience and Consciousness", at

[url]http://blog.360.y...Q--?cq=1[/url]][url]http://blog.360.y...Q--?cq=1[/url][/url]&p=174

"Some of the challenging interesting things to learn and search about memory via and by neurons are if, like its parent immunity, it is founded only on structural tags or on/also the location of the tags in the brain, and or/also on intimate linkage between the tag and a neuron's dendron, which is a physical modification/adaptation of the OCM, the oldest and most evolved organ of Earth's prime-stratum organism, the genome."

The "memory tag" possibility is discussed at
http://topics.sci...INS.html


The evolotionary tie between the immune and memory systems is so obviously a plain common-sense possibility that it must be scientifically probable...again, as common-sense is the best scientific approach...


Dov Henis

[url]http://blog.360.y...Q--?cq=1[/url]]