PSYB51H3 Lecture Notes - Lecture 12: Angular Velocity

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1 Oct 2011

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PSYB51 Lecture 12
Short Answer Question:
What is haptic perception? Why can you say that action is for (haptic) perception? Why the reverse is true
too: perception is for action?
Is from touch haptic perception is the process of actively feel/explore objects using your hands for
recognizing/ identifying of object, surface and their properties . This is useful in darkness e.g. feel for
light switch. Haptic perception is different compared to just other somatosensory perception (just touch)
is for this perception you need active exploration in order to get clearer perception. Haptic perception (
meaning you actively explore) is better because we use muscles actively and this gets at more info via
efference copy ( info about what we‟re doing w/ our muscles). The efference copy also allows additional
info about where is actually the fingers in space thus, allows for integration of where your hands are at
different times in space.
Perform certain type of action (usually from hands) to gather information about certain type of (haptic)
features of objects. These actions involve using hands with different strategies/actions (stereotypical) to
measure different features (e.g. weight vs. texture). The reverse is also true that perception is meant to
guide our actions for e.g. stable grasping of cup as you drink that doesn‟t allow the cup to slide
between your hand & spill coffee. The perception of your hands will guide the action of your hand to
grasp the cup properly.
Final Exam w/ 60 mc & 3 out 4 SAQ for SAQ focus on later lectures
**** Odour = in CANADA ODOR so whenever it spelled ODOUR Spell it ODOR *****
- We have 6 senses (vestibular system not long ago) further research leading to discovery of new
Olfaction & Taste
- taste vs. flavour are 2 different things
when we smell something (use olfactory system ) that means we have some chemical interaction
w/ certain molecules (chemical compounds)
is only certain sets of molecules (chemical compounds) that we can perceive w/ olfaction (odors)
main are w/ these features:
o Volatile
o Small
o Hydrophobic
o But not all
For e.g. carbon monoxide is a small molecule but we can‟t smell it but is very
dangerous that‟s why you need a detector at your house
Human Olfactory Apparatus
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Nose have the main purpose of providing us w/ air (breathing)
o these swilling air that entering the nose is also what we need for the olfaction because
the air enters pass along the sensory apparatus thus, secondary purpose of the nose
Nose : small ridges, olfactory cleft, olfactory epithelium
Olfactory epithelium the “retina” of the nose & has 3 type of cells:
o Supporting cells - pretty much limited to supporting functions (not have anything to do
w/ actual perception)
o Basal cells are (infants) precursors of OSNs
o Olfactory Sensory Neurons (OSNs) - are the cells that actually do engage in perception
are cilia protruding into mucus covering olfactory epithelium -- OR (olfactory
receptor) :
are designed somewhat like hair cells (similarity to auditory system & as well as
the vestibular system)
the difference is that the auditory & vestibular system use these “hairs” that is
sitting in the dendrites of these neurons for mechanic changes these are
„mechanoreceptors‟ (also found in touch )
for the olfactory system these (hairs) cilia work in „chemical‟ way -- they
interact w/ odorants (so whenever chemical (odor) lock onto these receptors ,
action potentials are elicited & are send along the Olfactory Nerve to olfactory
olfactory nerve which is Cranial Nerve 1 (basically multiple bundles of axons looks like brush)
goes through the skull into the brain (especially into olfactory bulb)
o imagine have car accident & hit your front head brain inside the skull hit the front
which could cause brain trauma but at the same time olfactory bulb kind moves forward
when that happens could have olfactory nerve are being sheared off
(equivalent to shaving razor) as result left w/ Anosmia cannot perceive smell
o another reason (lesion to olfactory nerve) causing Anosmia Infections of these axons
& causes swelling of these axons
because these axons passes through skull the axons squeeze themselves into
when you cannot smell can‟t sense flavour of the food but know taste whether
something is sour or sweet , also cannot smell potentially dangerous fume
o another reason for anosmia or lack of smell is during earlier stages of Alzheimer &
Parkinson -- can use this as symptoms to diagnose Alzheimer & Parkinson
anosmia or lack of smell is quite common
Olfactory Bulb
Nerve enters the Olfactory bulb it sits just 2 finger underneath the frontal cortices
Olfactory bulb is where the axons from olfactory neurons will synapse onto mitral cells and tufted
cells in such a way called “Glomeruli”
Glomeruli spherical structures inside olfactory bulb Glomeruli is organised in Chemo-
topography manner
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o These glomeruli will code for different olfactory receptors specific for certain type of
odors (different chemical structures/ compound)
After Olfactory Bulb have connections to other parts of brain :
o Olfactory Cortex have discussion on where exactly this structure really is but is
somewhere in the temporal cortex rather than medial sides
o Amygdala- hippocampal Complex have clear connection to memory/ emotions
o Entorhinal Cortex also have connection to memory
Genetic Basis of Olfactory Receptors:
1000 different types of genes that are involved in forming these different ORs
o each codes for single type of OR (olfactory receptors - cilia of OSNs) need single gene
to determine the structure of a single ORs
don‟t usually all the genes use only something like 30-40% of these genes
most of these genes are dormant (have them but never really use them to create ORs called
o in dogs 20% of them the actual amount of genes being expressed are way more than
humans in humans 60-70% are pseudogenes
there is speculation that there is a trade-off b/w vision & olfaction w/ dogs being
much more good at smelling things & humans better w/ vision
o Humans have much more capability in smell than we actually use but we could change
that to some extent w/ training
Multisensory Perception
Olfaction is sensory perception itself but it often comes together w/ other senses/ system
typically w/ somatosensory system
o Odorants can stimulate somatosensory system (touch, pain, temperature receptors)
For e.g. if you smell something peppery also experience pain perception (feel
something burning inside your nose goes the pathway of Crania Nerve V)
o These sensations are mediated by the trigeminal nerve (V)
From Chemicals to Smells
Shape-Pattern Theory is probably the dominant explanation for how we sense smells
o The theory is that we smell odours at ORs in some kind of key-lock fashion odours
function like a key & odour receptors is like a lock
o so if proper key goes into the proper lock lock/ Odour receptors open & have action
potential have some kind of sensation based on that
= Basically the match b/w odour (key) & odour receptors (lock) odour
receptors are like the negative version of odour
Odorant might lock into different types of receptors doesn‟t have to perfect match
Odorants could have all sorts of molecular structures w/ different versions of structures when
we talk about the pattern part of the theory is how they deal w/ this
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