Memories

  Memory   (All credits to: The Human Brain – Rita Carter)

Memory is basically a broad term used to represent a number of different brain functions. They are stored in fragments all around the brain. You react towards past memories using the same neurons that created that memory. Memory can be as simple as reciting phrases or recognizing people, walking, or even knowing that the cereal is waiting in the right most cupboards. Different events or phenomena involve learning or the full/ partial reconstruction of the past. 

  When you re-call an experience you recollect (recreate)  it. Recollecting makes the original neurons even more involved in the past experience this makes remembering much easier and then to a point that it simply pops up into your consciousness more frequently. So, repeatedly reconstructing memories makes it easier to recall. For example, lets take something simple like walking. You walk very often, so this memory is for your motor cortex(movement center - see previous posts). This memory is then stored.

  When a memory sparks off, the hippocampus triggers various aspects of it in unison. For example, remembering a pet dog Different areas of the brain recall different things about this dog. Such as feeding the dog, the dog will howl, or even the roughness of its fur. 

Thalamus – Directs Attention

Parietal Lobe – Spatial memories (cognitive, records memories)

Frontal Lobe – Working, processing memory

Cerebellum – Memory and events linked by time

Hippocampus – converts short term memory into long term

Amyglada – Emotional memory is store

Mamillary bodies – episodic memories (memories you can recall)

Temporal Lobe – General knowledge

Declarative memories are facts you can bring to mind consciously. This is processed by the hippocampus.

  Short Term memories will stay until they have no further use, such as a phone number you only use once. Long term memories will be recalled even after years or decades. It will take 2 years at least for a long term memory to form. 

  Working memories are important. Processed in the frontal lobe, it holds a plan of action based on past experiences. This includes calling pieces of memory from all over the brain. Brilliant tacticians have a good working memory.

  Memories from different senses are stored in the limbic system (found in the temporal lobes). This will remind you of the mushy texture of rotten banana or the stench of a dead lizard. Perhaps even the voice and tone that lets you know that your father is angry at you.

  

  

Sense of Smell- Olfaction

    Vision has become the key sense for us humans today. But the sense of smell (olfaction) remains very important to our survival because it will warn us of hazardous substances in the area. Perhaps rotting food.  Other animals such as snakes depend on the sense of smell for many things. Such as the positioning of potential prey.The sense of taste and smell are very closely linked.

    Smell is a chemical sense, like taste. Special receptors in the nasal cavity detect scent molecules. The molecules travel up the nose because of air currents. Sniffing, obviously will take in more molecules giving you a better smell. Olfactory receptors, located at the top of the nasal cavity pick up scent information and send it through electrical impulses to the olfactory bulbs in the limbic system. 

  The Olfactory bulbs are located in the limbic system. They are in control for many things such as emotions, desires and instincts. This is why smell can trigger emotional reactions. Once processed by the Olfactory bulbs your reflex will take place. This is how olfaction occurs.  

Credits: The Human Brain
Author: Rita Carter

Cells in the Brain

Neurons are clearly differentiated by their way to communicate and interact with other cells through electrical and chemical signaling. They come in many different morphologies. This is determined by their tails, nucleus, and branches. Axons are the long  hot dog bun connected body of the Neuron.Dendrites are the branches which come off the end of the axons known as terminals. Dendrites are used for signaling in a process called synapses. Synapses helps convey information from neuron to neuron in a nerve. At the end of each dendrite is a synapse.

  

    This synapse will meet with others from different neurons to continue a message towards or from the Central Nervous System (CNS). Axons are the tails of neurons. On one side of them is the big circle where the neurons and axons exist. On the other side is the axon ending. There are 100 billion neurons existing in the human brain. The amount of information that 1 neuron took in its life time is measured in converge. And the amount of information 1 neuron sent in life is divergence.

    Glial cells out number neurons 3:1. The word Glial comes from the Greek word Glia or glue. This is because the Greeks thought Glial cells hold the nervous system together. Although they have large numbers they do not interact with electrical or chemical signaling or synapses. The purpose of Glial cells is for helping in recovery such as concussions, speeding up signaling, or cleaning wounds, all depending on what Glial cell type they are..

Different types of Glia include

Oligodendrocytes- Only found in the CNS. Lay a layer of lipids called Myelin to speed up electrical signaling and synapses of neurons.

Schwann cells- Only found in PNS also lay Myelin in nerves.

Microglia- Remove debris from injuries in normal cells.