Exercise Two: Perception and Cognition Research(smell)

Exercise Two: Perception and Cognition Research- by Cathy Lai

Do you know!?

The olfactory system, which senses and processes odors, is one of the oldest and most vital parts of the brain. For most animals, it is the primary mode of communication and influences many important functions, including reproduction and taste. Scientists are just beginning to learn how the olfactory system works.

The nose contains specialized sensory nerve cells, or neurons, with hairlike fibers called clilia on one end. Each neuron sends a nerve fiber called an axon to the olfactory bulb, a brain structure just above the nose.

Odor molecules entering the nose are thought to be recognized by receptors found in cilia of olfactory neurons. Neurons with specific receptors are arranged randomly within zones in the olfactory lining of the nasal cavity. Signals from neurons with the same receptors converge on structures called glomeruli in the olfactory bulb. The pattern of activity in these glomeruli creates a pattern or code that the brain may interpret as different odors. The information is carried by nerve fibers to many brain regions, where it affects thoughts, emotions, and behavior.

Unfortunately I didn't come to the first class due to the ticket. I tried following the description and hopefully I'm on the right track for this exercise.

resource:http://www.sfn.org/index.cfm?pagename=brainbriefings_smellandtheolfactorysystem

Exercise Two: Perception and Cognition Research (Smell)

Exercise Two: Perception and Cognition Research (Smell)
Desiree Beaubien & Bradley Crystal

In many cases, smell is the first of the senses to respond to stimuli. It prevents us from drinking rotten milk and it warns us if there is fire. Such odors and many others are detected by sensory cells called Chemoreceptors.

Chemoreceptors which are made up of about five million nerve endings and make up a patch about the same area as a quarter, detect odor molecules in the air. At the end of each nerve is a knob shaped Dendrite. Dendrites sends electrical pulses through axons into the Olfactory Bulb. Some of the nerves which transmit information to the Olfactory Bulb are responsible for transmitting odor information while others are responsible for transmitting pain information. This is why when the odor of a chemical such as Ammonia is inhaled, the body feels a stinging pain. This is the body's natural response to what may cause harm.

The Olfactory Bulb is part of the brain's Limbic system. This area is responsible for memory and emotion. The Bulb has direct access to the part of the brain which is responsible for associative learning which creates conditioned responses. Every time the body encounters a new smell, it is linked to an even, person or place and a link is forged by the brain. When the smell is encountered again, the brain can instantly recall the memory or emotion associated with it.

Source: How Stuff Works - http://images.google.ca/imgres?imgurl=http://static.howstuffworks.com/gif/pollution-sniffer-2.gif&imgrefurl=http://science.howstuffworks.com/pollution-sniffer1.htm&usg=__JP6U77MpiqNc9_UMeFh-i1IgeRg=&h=296&w=400&sz=48&hl=en&start=3&um=1&tbnid=VlEBnRCz_Ji65M:&tbnh=92&tbnw=124&prev=/images%3Fq%3Dolfactory%2Bdiagram%26um%3D1%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US:official%26sa%3DG

Exercise Two - Perception and Cognition Research

Exercise Two: Perception and Cognition Research

By: Sarah Sien

Sight

Sight is the ability to see, and eye is the organ of sight. The eye is a complex organ that is constructed with the pupil, the iris, the lens, the cornea, the retina and many more. First of all, the pupil is the round opening located at the center of the eye in the iris that determines how much light can enters the eye through the transparent lens. Both the pupil and the lens are covered by the cornea, which is the outer part of the eye and is transparent as well. The Retina is the lining at the back of the eyeball where the light falls on. The retina sends electrical signals to the brain and the signal are carried by the optic nerve. Furthermore, vitreous humor is a clear, transparent and colorless jelly, that fills the space between the lens and the retina lining in the eyeball.

Unfortunately, I missed the first class due to a schedule change, and if I were in class I am sure I wouldn’t be able to come up with a precise system model for sight anyway, since I only remember the pupil, the iris and the lens.

Word Cite:
Scholastic Science Dictionary. Scholastic Inc. New York. 2002.
http://en.wikipedia.org/wiki/Eye

Exercise Two:Perception & Cognition Research

IN TOUCH WITH TASTE
By:Tarz Sachdeva

In our first class, we demonstrated a diagram to familiarize ourselves with the workings of the sense: Taste. Even though we touched all the essential elements, there was still some information missing that is now being discussed in the second exercise where the detailed information is provided. In addition to that it is essential to point out the misconception that the taste buds are only located on the tongue and have specific zones on the tongue for a specific taste.

The sense of taste begins with the Taste Buds. You might call the little knobs dotting the surface of your tongue taste buds, but you'd be wrong. Those are Papillae, and there are four kinds of them: fungiform and filiform on the front half, foliate and vallate on the back. Taste buds are sensory organs that are found all over the mouth: the tongue (maximum), the pharynx, the palate, the epiglottis and the entrance of the larynx and allow you to experience tastes that are Sweet, Salty, Sour, and Bitter and Umami. Taste buds have very sensitive microscopic hairs called Microvilli. Those tiny hairs send messages to the brain about how something tastes, so you know if it's sweet, sour, bitter, or salty.

DID YOU KNOW: The average person has about 10,000 taste buds and they're replaced every 2 weeks or so. But as a person ages, some of those taste cells don't get replaced. Smoking also can reduce the number of taste buds a person has.

Where does the message go in the brain?

When something tasty enters the mouth, its chemicals are dissolved by the saliva:

• The free-floating molecules enter the taste bud through a pore in its center.
• Microvilli excites that cell into issuing a series of chemical and electrical signals.
  
• Taste messages shoot up a pathway to the medulla.
• From there the information is relayed to the gustatory cortex for conscious perception of taste (located right under the somatosensory cortex)
• and to the hypothalamus, a mygdala and insula, which are responsible for behavioral responses like aversion, stomach secretion, and feeding behavior.

Also:
It's important to thank your nose. While you're chewing, the food releases chemicals that immediately travel up into your nose to trigger the olfactory receptors inside the nose. They work together with your taste buds to create the true flavor.

REFERENCES:

1. http://www.msginfo.com/about_taste_how.asp?bhcd2=1231697150
2. http://www.wisegeek.com/how-does-the-sense-of-taste-work.htm