What are memories?|How memories are formed?

What are memories?

Memories are a collection of data Such as the taste of ice-cream, the best moment with a friend, our first kiss, the punishment given by a teacher, and many more. In our daily routine whatever we can see, touch, smell, feel, hear and taste will become a part of memory. Memory is not a physical substance that we can insert in our brain like hard-disk inserted in CPU. Every second several memories are forming and destroyed, memory can last up to a minute or for a lifetime.
In short, memories are the collective data of our past in order to or influence our current behavior.

History of memory

Before we go deeper, we have to look at our past, how memory comes into the picture of neuroscience. In 1953, there was a person whose name was Henry Molasium who met an accident while riding a bicycle. In this accident, he got damage to his skull and spending a few days in hospital he came back home.
Due to his damaged skull which couldn't be repair by doctors, he began to experience severe seizures. Then doctors decided to remove the part of the brain which was responsible for seizures.
Parts that should be removed from the left and right temporal lobes are mainly the Hippocampus, Amygdala, and part of the entorhinal cortex.
Seizures were completely stop, but he began to suffer from anterograde amnesia. It means he will lose his ability to form new memories.
Doctors were trying to figure this out but until 1950 there was no idea about memories and thus research started on memories.
Henry Molasium (H.M) starts forgetting things which include facts and ideas but he can learn habits like riding a bicycle or learning new dance steps.
Memories are of different types because H.M can able to remember certain memories. So memories are classified into different groups and they are:-

H.M can able to retain his Non-Declarative memory/Procedural memory and was not able to remember his declarative memory. In 2008, H.M died and due to research purposes, and his brain was divided into thousands of parts. Thanks to H.M for his contribution to the research. So different parts of the brain are responsible to retain different types of memories such as.

• The Amygdala used to store the emotional responses.
• Motor memory is store in Cerebellum
• Memories of facts and events are store in Thalamus and Hypothalamus which is located in the medial temporal lobe.

  How does memory is form?

  Memory is nothing but firing of neurons when we experience something. our brain talks with the help of neurons and neurons communicate with the help of synaptic connections.
After doing something repeatedly, neurons connected to that task will get stronger and eventually make a neural circuitry.
Neural circuitry will become more efficient in communicating the message and this will make a shift to Long Term Memory.
while neurons that do not get involve much, will get weaker and serve no purpose to be alive. Neurons that fire together, wire together.

Sensory memory is the shortest of all memory as it lasts only for 1/2 - 1/4 of a second. The stimuli detected by our senses can be either deliberately ignore, in which case they disappear almost instantaneously, or perceived, in which case they enter our sensory memory. This memory doesn't require conscious attention.
After sensory memory it will store in the gray matter i.e. in cortex in the form of short term memory. This memory will last up to 60 sec, short term memory is also known as working memory for e.g short-term memory can be used to remember a phone number. After experiencing STM for a long time it will go through the hippocampus where a group of proteins will work together and will make that memory to long term memory in the cortex. Where it will be store as a permanently for a lifetime.

Why do we lose memories?

       When we experience something like riding a bicycle, that experience is converted into electrical energy that zips along with network of neurons. First information is available in short term memory and then will reside in the hippocampus after than will eventually become long term memory. Neurons in all our brains communicate with each other with the help of synapse using neurotransmitters.
If two neurons continue to process information for a long time, they will become more efficient and this process is called Long Term Potentiation and will be there for the long term.

     We may lose memory due to age one research has shown that we lose 5% neurons every 10 years,by the time when we are 80 year old there will be a total loss of 20% of neurons. And thus we will lose neurotransmitters such as acetylcholine which is vital for learning.

    Another factor can be chronic stress which makes our body on hyper-alert and can kill our brain cells and degrade our learning capabilities.
Depression and isolation can also be the cause,40% of depressed people are more likely to develop memory problems.
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