What's in a smell?

When you smell the lovely aroma of freshly baked bread you probably don't think "wow those are some good smelling chemicals", but more likely your mouth waters and you might even become hungry. You might also remember a time you were out with friends and had a pastry or a time your mom baked bread. Smell is very important; it can alert us of a fire, prevent us from eating rotten food, and gives food much of its taste.

While we can smell more than 10,000 different smells and have hundreds of olfactory receptors, rodents have thousands of olfactory receptors. So how exactly does smell work? Let's start with some basic anatomy and physiology involved in olfaction, which is the sense of smell. Just as your nervous system uses neurons to function, smell also has specialized neurons for smell called olfactory cells. The special cells line the back of your nasal passages and have tiny threadlike hairs called, cilia. If the olfactory receptor is stimulated an impulse will be sent.

The cilia will then send the impulse (smell) to the olfactory bulb, which then sends it to certain areas in the brain. The brain is then left to interpret the pattern of the molecules or odorants as a specific odor. This takes place in the olfactory area in the cerebral cortex. 

While this explains how we are able to associate a certain chemical trace with a "smell", why is it that certain smells bring back memories? A certain breezy perfume may bring to memory a day at the beach or a certain musty smell may remind you of days spent at grandmas. 

Well as the olfactory bulb sends the odorants to the cerebral cortex, it also sends it to other parts such as the hippocampus, hypothalamus and the amygdala. These structures (including the olfactory bulbs) are part of the limbic system, which deal with memory and emotional behavior. 

The reason smells can trigger a memory is because when you first encounter a new odor you connect it to a certain moment, person, or place unconsciously. For example, if you were to smell minty scent while eating a candy can you would associate a candy cane with the smell of mint. The next time you get a whiff of mint you will (probably) remember that moment and how you felt. So why is it that not everyone likes the same smells? It is because everyone has a different memory and mood attached to different scents; what may have made you happy while smelling mint may have given someone a headache. 

I hope this clarified how olfaction occurs, happy smelling!

References:

Kalat, J. (2012). Biological Psychology. Cengage Learning.

http://health.howstuffworks.com/mental-health/human-nature/perception/smell.htm
http://www.bbc.com/future/story/20120312-why-can-smells-unlock-memories

How to improve your ...um what's the word???? Oh, memory!

Have you guys ever experienced this???

Well if so, you have experienced the 'tip of the tongue' phenomenon (not a very clever name, right?)
Although this may be one of the few times your memory "fails" you, your memory is actually amazing. It may sound silly, but do you know what memory is?? It is the ability to encode, store, and retrieve information and experiences at any given moment. I am sure if I asked you for your birth date you would answer automatically as well as if I asked for your name, age, or mother's name. This information was probably told to you by your parents at one time and you successfully encoded, stored, and can now retrieve it on the spot.

First, there are many different types of memory.

Here is a brief summary in the three main types of memory.

   

  Sensory Memory: This is the shortest type of memory that is detected by the senses (touch, taste, smelling, hearing, and seeing). It only lasts about 1 second!! It can either be ignored or perceived and that is what makes it so short.

     Short-term Memory (STM) or Working Memory (WM): It used to describe events that have just occurred and are currently manipulating or thinking about. While it is short lasting as well, it can last around 30 seconds to a minute, but beware once you stop focusing or become distracted it is gone forever.

     Long-term Memory (LTM): This is typically the type of memory we think of when we remember our 8th birthday party, first kiss, learning to drive, or graduation. It refers to memories that happened further back and have been encoded, stored, and available for recall. We are able to store unlimited amount of information for infinite amount of time. 

Here is a good video summary on the types of memory as well as tips to improving your memory.

 

Easy ways to improve memory

1. Paying attention

       - As obvious as it sounds giving your full attention to a task helps.

2. Coffee

       - helps because as a stimulant drug it increases levels of arousal making it easier to retain the information.

3. Exercise

       - Other than for memory exercise is good for many things (health, mood, alertness...) as well.

4. Sleep

       - Studies have shown if you take a break during studying your brain can consolidate and solidify information. 

Nap anyone?

5. Chewing gum

       - It increases activity in the hippocampus, a very important area for memory.

       - Increases oxygen levels.

6. Meditating

       - It increases the cerebral cortex, the area responsible for concentration.

7. Chunking

       - You have probably used this before such as when you read a phone number or your SSN. It helps because you put the information into more manageable pieces.

8. Use imagery

        - When you're going grocery shopping use imagery when thinking about what you need.

Try these and see what works for you!

References:

Kalat, J. (2012). Biological psychology. Cengage Learning.
http://www.businessinsider.com/research-tested-ways-to-improve-your-memory-2014-3
http://www.human-memory.net/types.html

Cutting the cables: The split brain

Epilepsy is a serious neurological disorder often characterized by recurrent episodes of increased and abnormal activity in the brain. Epilepsy can occur due to gene mutation, trauma, tumors, infections, or even from the brain being exposed to toxic substances however, the cause is usually unknown.

The Surgery

While there are a couple of methods of treatment, the more severe cases of epilepsy in patients can be treated by performing a rare surgery that cuts the corpus callosum called corpus callosotomy.

It is a risky and invasive treatment option because the corpus callosum will not heal therefore is left as last alternative. As you may know, the main responsibility of the corpus callosum  is allowing communication between the two hemispheres. It is the reason why even though each hemisphere is specialized for certain tasks it never feels as if two people are sharing one body. Severing the corpus callosum works because it stops the epileptic seizures from crossing into the other hemisphere and therefore shorten the time the seizures last as well. Sometimes if the surge of electrical activity cannot "ping" back and forth, a seizure will not even develop! 

Aftermath

You may be thinking, "this sounds great, no more seizures!" however, any surgery has risks associated with it and this is no exception. People who have undergone corpus callosotomy are often referred to as split-brain people who although maintain motor and intellectual abilities have difficulty performing tasks that are not familiar to them. Severing the corpus callosum affects what split -brain people can see; if an object is presented to them in one hemisphere, the other will not see it. One benefit found in split-brain people is they can use their two hands independently in a way non split-brain people cannot. What do I mean by this? They have the ability of simultaneously moving the left hand and right hand in different directions. They are able to do this because they can plan two actions at once since each hemisphere process information independently. Eventually conflicts between the two hemispheres will diminish as the brain begins to adapt and use smaller connections between the hemispheres.

Hemisphere Specialization 

Studies have shown people suffering damage to a certain hemisphere lose specific abilities and functions which leads to the concept of lateralization. Lateralization is division of labor between the two hemispheres such as the left hemisphere to be involved in language and logical thinking with the right mainly specialized in emotions and creative thinking.

Patients with damage to the left hemisphere are more apt at recognizing and understanding gestures and facial expression because the right hemisphere is better at perceiving emotions, recognizing humor and sarcasm, as well as spatial relations. With the left hemisphere "out of the way", the right hemisphere is able to do what it does best, recognizing emotions. Need clarification? Here is a video that further explains the concept of lateralization and split-brain theory.

In conclusion...

References:

Kalat, J. (2012). Biological psychology. Cengage Learning.

http://www.nature.com/news/the-split-brain-a-tale-of-two-halves-1.10213