• General sensory perception that responds to odors
• Airborne molecules interact with nasal receptors
• Olfaction depends on molecules floating through the air
• When you smell something, you smell a little piece of whatever it is

• Receptor surface for olfaction
• Behind nasal passages/in the nasal cavity
• Composed of receptor cells and support cells
• Each receptor sends a process into a mucous layer known as the olfactory mucosa
• Chemicals in the air that we breathe dissolve in the mucosa to interact with the cilia
• The receptor surface of the epithelium varies widely across species (in humans, the area is much smaller than other animals)
• Roughly analogous to the tuning characteristics of cells in the auditory system, olfactory receptor neurons in vertebrates do not respond to specific odors, but rather to a range of odors

• Can respond to any number of different shapes of molecules
• Olfactory receptor proteins are GPCRs
• Humans ~350 genes (vs. other mammals at 1000 genes, fish at 100 genes, mice with 13000 genes)
• Number of genes is equivalent to number of GPCR receptors
• 350 functional olfactory receptors allow us to smell ~100,000 different odors
• We also have ~650 nonfunctional pseudogenes (not transcribed or translated into protein that actually works)
• Any one substance might activate a number of receptors by differing amounts (brain is able to compare different signals coming from different cells and extract a particular odor)

• A deficit in olfactory perception
• General anosmia - total loss of smell
• Specific anosmia - due to gene changes in olfactory GPCRS

• Right above the olfactory epithelium
• Receives neural input about odors detected by cells in the nasal cavity
• Axons of olfactory receptor cells extend directly into the highly organized olfactory bulb, where information about odors is processed 
• Goes to thalamus/orbitofrontal cortex
• Also amygdala/temporal cortex/hypothalamus (limbic system)

• Olfactory bulb to thalamus to orbitofrontal cortex
• Also to amygdala/temporal cortex/hypothalamus (limbic system)
• Olfactory epithelium is connected through olfactory bulb

• Transient Receptor Potential
• TRPV1 -activated by chemicals such as capsaicin, peperine
• TRPM8 - sensitive to menthol and cold
• TRPA1 - activated by pungent chemicals such as those from the mustard family (mustard, horseradish, wasabi)

• Chili peppers (Capsicum annum) - many varieties, come from S. America, Columbus "discovered" and called them peppers because he was originally looking for black pepper)
• Capsaicin - molecule that gives rise to hotness, major "hot" substance from chili peppers
• Capsaicin receptor - Ca++ channel, depolarization
• TRPV1 - capsaicin receptor
• Why hot? Because capsaicin activates same receptors as temp., receptors all over skin/body, heat is the speeding up of molecular motion

• Cooling properties
• Menthol - named after mint plant
• Activated by cold in the same way capsaicin reacts to heat
• Menthol receptor - Ca++ cell depolarization
• TRPM8 - menthol receptor

• "Pungent" chemicals from plants in the mustard family
• All contain allyl-isothiocynates
• Mustard, horseradish, wasabi
• Also heat-reactive
• TRPA1 - isothiocynate receptor

• Pit vipers use inferred
• Use TRPA1 receptor (activated by heat AND gives rise to a feeling of heat)
• Receptors located in pit organ
• TG = trigeminal nerve (5th cranial nerve) - goes into the brain, carries signal from this pit organ (among other things)

• Somato - means body
• Somatosensory - things that interact with our skin
• Some of these receptors are TRP type receptors responding to temperature (hot or cold) and other receptors are activated only by over the top stimuli (really high low)
• Pain, touch, pressure
• Associated with hair folecules

@font-face { font-family: "ＭＳ 明朝"; }@font-face { font-family: "ＭＳ 明朝"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 10pt; font-size: 12pt; font-family: Cambria; }.MsoChpDefault { font-family: Cambria; }.MsoPapDefault { margin-bottom: 10pt; }div.WordSection1 { page: WordSection1; } clusters of cells along spinal chord that receive input from somatosensory cells

• Region of the visual world that stimulates a receptor cell of neuron
• Pain
• Touch/pressure - mechanoreceptors, often associated with hair follicles, hair is there to provide an added level of sensitivity
• Temperature

• Anterior parietal lobe (relative location)
• Posterior to the central sulcus (relative location)
• Postcentral gyrus (actual location)
• The connectivity between the somatosensory cortex and the body is contralateral

• Neurosurgeon in Canada
• Began this work way back in the 1930s, long before people were doing any kind of brain recording
• Used surgery to test patients' response to stimuli (would poke electrodes in the brain and ask patient if they felt anything or watched to see if anything twitched)
• Put together the Penfield Map or Somatosensory Homunculus (literally means "little guy" (body map along the postcentral gyrus in the parietal lobe, you can take a frontal section and look at the edge of that slice)

• Created by Wilder Penfield
• Literally means "little guy"
• Body map along the postcentral gyrus in the parietal lobe
• You take a frontal section and look at the edge of that slice

• Region of the cerebral cortex lying mostly on the parietal operculum
• S2 activation in response to light touch, pain, visceral sensation, and tactile attention
• First the somatosensory cortex goes to the S1 then S2 then S3 and so on 
• Highly interconnected
• Lesion in this can result in "neglect syndromes"

• Lesion in "secondary"/"supplementary/"association input can result in these
• You don't pay attention to a certain part of the world (can also happen to vision)
• You're not blind and if you're forced to pay attention you can see it but in the ordinary world you're unaware
• With touch people don't pay attention to certain parts of their bodies

• The loss of being able to identify what is going on
• If you had your eyes closed and were asked to identify something by manipulating it with your hand you would not have any clue, you could feel it and recognize that you're feeling it but you can't put the info. together

• Mice whiskers are main sense of touch
• If you look at a mouse brain there is a somatosensory map of the mouse's brain and body - the whiskers have substantial representation
• Whisker barrels - S1 in the mouse brain
• Amputating a whisker - the nearby barrels actually expand, reorganized their connections in some way so they receive information from the surrounding whiskers (neuroplasticity)

• Ability to alter neural patterns in some way
• Forming new connections that were not there before
• Strengthening synapses

• What happens in the human brain after an amputation (ex. arm)
• Victims have the perception that the thing they lost is still there (they can physically feel it and feel like they can move it)
• The adjacent areas take over that part of the map which is no longer there (map reorganization)

• Adjacent areas to amputated limb take over that part of the map which is no longer there

• Apo - off, detached
• Temno - cut
• Philia - liking, loving
• This person WANTS to have a body part cut off
• They don't like it like this part of their body and are actually very upset and constantly obsessing over it
• Some patients actually DO end up cutting off their body part, after which they feel better
• Maybe there is some kind of disruption for the body map for that part of the body for regions of the brain that are building the map up and connecting with the emotional experience

• Anterior of the central sulcus
• Called the precentral gyrus
• Penfield discovered this map of the body associated with motor movement
• Controlateral mapping of the body with this as well
• M1 lesion - paralysis, motor equivalent of scotoma

• A disorder caused by damage to specific areas of the cerebrum, characterized by loss of the ability to execute or carry out learned purposeful movements
• Victims can still move (no paralysis) but there is a disruption in the organization of movement

Mirror Neurons

• Active during movement AND during observation of movement areas in the frontal lobe (cortex)
• In the motor areas
• Some of these neuron cells were active when the monkey moved and when the monkey saw someone else doing the same thing
• They respond to a mirror image of what is going on in the world in the same way that they respond to their own body

• Means of communication of the use of signs, sounds, and gestures having understood meanings 
• Animal communication:  bird songs, primate calls, honeybee dance
• Human language:  great complexity

• Disorder of language due to a lesion
• Study of these led into the modern area of neurology 

• Identified a disorder of language in people (like not being able to speak and write) even though they were not paralyzed
• After people like this died (often due to stroke) he would look at their brain and identified a region of the left frontal lobe (Broca's area)
• Broca's aphasia:  production aphasia for spoken word and written language (victims can understand buy cannot speak or write)

• A contemporary of Broca
• Wernicke's area:  found an area in the left posterior temporal lobe
• Wernicke's aphasia:  comprehension aphasia for spoken and written language (they can speak but they have a problem comprehending language so they can't understand that people tell them)

• John Wada developed the Wada test to see prior to brain surgery which hemisphere the language areas were in
• Usually they were on the left but not always
• The reason that they were finding this out is because they were going to do surgery on this person (usually for seizure disorders
• A barbiturate/sedative hypnotic drug was injected into one of the carotid arteries (carries blood from the heart to the brain) at a time while the person is awake and conscious and able to respond to questions

• The whole left brain right brin thing started with him
• Got Nobel prize in physiology/medicine
• Pioneer in illuminating lateralization of function in the human brain
• Presented with the opportunity to study patients with corpus callosum

• Thomas Harvey performed autopsy on Einstein in 1955
• Einstein died of a ruptured aorta and Harvey kept the brain
• Years later he cut up the brain and sent it around to people to study 
• Marian Diamond suspected that glial cells might be important
• She found that there were a couple areas in the frontal and parietal lobes in Einstein's brain that contained a large number of glial cells
• Something different about gyrus and sulci

• Left hemisphere:  language, calculation, visual detail
• Right hemisphere:  nonverbal linguistic, 3-D spatial, visual gestalt, harmony, timbre

• Denial
• Rationalization
• Projection
• Reaction formation - taking the extreme opposite stance (exaggerating abilities of paralyzed hand as a way for dealing with the problem

• How is mind related to the physical processes in the body?
• Idea that mental experiences are intimately related to the body
• We can investigate the mind-body relationship through brain lesions, brain imaging, sensory pathways, pharmocology, and studying different sorts of brains (like Einstein's)

• French scientist
• Interested in how body and brain worked
• Lots of dissections (anatomy)
• Before any notion of how electrical signals work
• Dualism - mental and material domain

• A Treatise Concerning the Principles of Human Knowledge
• Bishop of Cloye (connection to Cloyne Court) Reality is really coming from perception (Mentalism or idealism)
• There is no objective existence (all we have is our mental experience)

• Everything is describable in terms of physical properties

• When you put things together, you get a new property that didn't exist before

• Idea was to focus the study on the external world
• Newton put Gallileo and Copernicus' ideas together