Our behavior is made thanks to our life’s experiences, which gives us information to create reflection on the past, generate new ideas and acquire languages as a way to communicate each other and express our self.
Types of memories
- Short memory: we can know it also as “work memory”. It allow us comprehend what we are listening, reading or seeing. It is a very important element, because it lets us make a difference between the present and the past. Thanks it, we can renew the information of the past.
-Flash bulb memory: when we remember some important situation, these kinds of memories relate the situations with our feelings that we felt in that moment.
- Long memory: These are some of the moments that we have so long time ago.
If we don’t have memories, it is impossible do all our daily routine. The memory, all together, constitutes our knowledge. This knowledge is essential to understand how the world is. Our behavior is according to and depends of the memories. Even the brain can do some categories and save the memories there. But there are some other things that brain can help us with; “Motor skills” referees to the ability that we have to remember how do something, but we can’t explain. For example, how ride a bicycle.
Episodic memory is the one that reefers to events that happened just once, in the past. For that reason, this kind of memory is impossible to improve or to verify his truthfulness . It is also very selective and personal, however, episodic memory is very important for create a self- view about the world. Due to his “personal” character, the episodic memory can be triggered by evocative sensory stimuli, as the sense of smell.
Referring tho the memory, the evocation of vivid recollections that you were unaware had been memorized, suggests that not everything is accessible by deliberate attempts at recall. In fact, there was a lot of experimentation in the 40’s using electric stimulation in specific areas of the brain which proved that episodic memories may not be readily recallable. After this experiments, it was concluded that specific memories not only have a physical basis but that each also has a particular physical location in the brain.
Various labels are used to describe different types or categories of memories. The hippocampus, for example, is the part of the brain that working memories are transferred into long-term explicit memories. It is implicated in stores of spatial memories required for navigation; structural brain scanning in humans indicates that the hippocampus stores detailed mental maps that help us to navigate. However, for procedural or motor memory it seems that the hippocampus is not required, so different types of memories are acquired and stored by different brain regions.
It is difficult if not impossible to directly study the physical mechanisms of memory formation and storage in the human brain. In the field of learning and memory, the experiments on sea slug, has provided an almost ideal model system to study the mechanisms of memory formation in the brain. Even, there are another examples of mollusks and a few types of virus and bacteria, that acts as a biological systems to research about the genes.
In fact, Eric R. Kandel, a Nobel-winner psychiatrist, discovered how memories are formed in an animal incalculably simpler than man. Using the reductionist strategy in small life-forms, we can approach to the human brain. An example of this humble life forms that are used on researching is the Alpysia; his brain has about 20.000 neurons some of which are large enough to the naked eye.
Well, another type of learning, is the sensitization, this means that when we get unexpected or strongly unpleasant stimulus our attention is more alerted
Think in the ticking of the grandfather clock, we heard it every time, but if this clock suddenly sounds loudly, we become aware of it.
This feeling last just a few minutes, and after that time, we started to ignore the stimuli again.
With the knowledge of the concepts like habituation and sensitization, Kandel has studied the memory in the short-term and long-term. In this investigation he observed what was going on in individual neurons and at individual synapses while the memory was being formed.
The mammals requires for short term memory and long term memory, are very different. just like in the Aplysia, the long term sensitization required new protein synthesis, but short term memory, did not. Because of these, there was a chance that Aplysia and and mammals’ memory formation was the same.
The Aplysia brain has about 20,000 neurons
The sensory neurons that innervate the siphon, and which respond to touch, excite the motor of the neurons, causing the gill to be withdrawn. The sensitizing stimulus to the tail excites these neurons and hen they are inhibited the sensitizing effects of stimulating the tail are blocked. The activation of these neurons is necessary for the sensitization memory to be formed.
The modulatory neurons are called like that because they alter the size and the duration of the response. Kandel's experiments showed that activation of modulatory neurons could strengthen the synapses those which already existed between sensory neurons and motor neurons. The research showed that the neurotransmitter of modulating neuron is serotonin and that when a single puff of serotonin leads to sensory motor neuron synapse, the synapse is strengthened by a few minutes. And could generate a long-term change. The eyelic- AMP activates an important type of enzyme called kinease, which modifies the properties of particular target proteins by adding a phosphate molecule to them. This protein is called phosphorylation.
Finally, they have strengthened a synapse and modified the animal´s behavior in the short term. This I only a short-term memory because special enzymes quickly remove phosphates from proteins and return them to their original state, restoring the synaptic strength to its lower pre-sensitized level.
This was expected because it had been know for some time that short-term memories are formed even when all protein synthesis is prevented. Blocking the synthesis of new proteins, however, prevents long-term memory formation and this is as true in Aplysia as it is in us.
Involvement of the nucleus, could be achieved by the repetitive application of serotonin to the synapse and not to the cell body.
The synapse must initiate a dialogue between cell body and its nucleus. This dialogue activates the genetic information needed for the synthesis of a new protein required by the synapse for strengthening it in the long term. The short-term memory process is repeated in the initial step to long term. It produces cyclic- AMP synthesis and when it repeated serotonin delivery, levels of cAMP-activated kinease are higher, formation of log-term memory occur. This step actives the cyclic-AMP to get the synapse.
When Activated kineases enter the nucleus, they modify special proteins that interact directly with DNA. This mechanism produce that some genes are turned on immediately and other turned on later.
After this process the new proteins born from Aplysia are transported back to synapse. There they will maintain the strength of synapses. The conversion from short-term to long-term involve the growth of stronger new synapses. It needs the synthesis of new proteins.
Memory mechanisms are universal.
Two conclusions stand out after the experiments with sea slugs: There is a crucial target of adaptive change in the brain of any animal is the synapse. The molecular machinery have the function of alter the strength of synapse and the ability to communicate with cell´s genome, to consolidate short-term changes made locally at the synapse. It is a highly responsive, dynamic and active participant in the process of responding to the changing environment. Also Neurons´ joints fluctuate in strength in accordance with experience. Behaviour is adapted continuously according the latest experiences in our ever-changing surroundings.
Secondly, Genome´s structure are molecular mechanisms that allow experiences to change the pattern of gene expression in the brain. If we think where is from our mental abilities we needs to know that: Our ability to learn from experience, to benefit from nurture, is allowed by the way our genes are designers to respond to experience.
There are differences between human beings (mammals) and slugs, but at the level of cells, molecules and genes, mechanisms of memory are similar. Both have protein synthesis independent and dependent phases of short- and long-term effects on synaptic strength.
We expect that the development of “smart” drugs to improve our ability to learn and probably it recall to established memories. Drugs probably enhance the effectiveness of neurotransmitters involved in activation of genes required for long-term memory formation. Some drugs contribute with the lost of memory.
The best advice is Continue to learn, because the brain is a extraordinary plastic and responsive machine. It had a lot of information, synapses and when we grow older we lost brain power. As we train our bodies, we need to work the brain, the mental exercises is useful. The take.home message would seem to be “use it or lose it”
