PSYC 2800 Study Guide - Final Guide: Olfactory Receptor Neuron, Olfactory Bulb, Olfactory Mucosa

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20 Apr 2012
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Emotion
Cognitive interpretation of subjective feelings
Interpretation of physiological symptoms (chills, increased HR)
E.g., anger, sadness, fear
Can occur unconsciously and influence behavior
Motivation: What we do with emotions
Goal directed behaviour
Can result from emotions. Feel stressed so study.
Subjective; can occur without awareness. Ex: Eat without thinking
Neuroanatomy of emotion and motivation: Structures implicated=
Hypothalamus
Limbic System
Frontal Lobes
What Causes Behaviour?
Is it free will?
Possible explanation: brain needs stimulation? Experience world through
senses and engage in motor behavior to deal with it.
Sensory Deprivation
Subject is allowed only restricted sensory input: No sight, sound or
touch.
Low tolerance for deprivation and may even display hallucinations
If brain not receive stimulation , may produce it on its own
Hebb and Heron (1950s)
After about 4 to 8 hours, subjects became quite distressed; few
subjects lasted more than 24 hours
Brain has an inherent need for stimulation; one reason that we
engage in behavior is to stimulate the brain
Similar studies with rhesus monkeys: Do tricks to look through window
(stimulation) when deprived.
Drives and Behavior
Drive
Hypothetical state of arousal that motivates an organism to engage in
a particular behavior
Hungry-hunger drive-look for food
Drive theories of motivation assume the brain is storing energy for behavior
“Flush” model:
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Empty reservoir fills up over time, when full, engage in behavior to
empty reservoir again
Once a behavior is started, it will continue until all the energy
in its reservoir is gone
There are separate stores of energy for different behaviors
Later proved wrong, particularly when looking at non-biological drives
(friendship)
Neural Circuits and Behavior
Researchers have not been able to link drives and brain activity. Brain
during drive state no different than not in drive state.
Behavioral change correlates with changes in hormones and cellular activity
Example: A mans frequency of copulation is correlated with his levels
of male hormones, called androgens (male hormones related to level
of sexual interest). More of these hormones= have more sex.
Stimulating brain cells activated by androgens, induces sexual
behaviour. Motivational states correlated with brain activity.
Conclude: neuronal activity responsible for behaviour, not drives
Evolutionary Influences on Behavior
Innate Releasing Mechanism (IRM): Hypothetical mechanism that detects
specific sensory stimuli and directs an organism to take a particular action
Innate (part of genome); releasing (trigger behaviours)
Cats do attack behavior when shown Halloween cat image. Smile at
babies, they smile back (mimick). Blind kids show same facial
expressions .
The brain must have a set of norms against which it can match stimuli
so as to trigger an appropriate response
Although IRMs are prewired into the brain, they can be modified with
experience
Sexual stimuli not affect us when little but as we age, they have a different
meaning
Evolutionary Influences on Behavior (2)
Evolutionary Psychology
Discipline that seeks to apply principles of natural selection to
understand the causes of human behavior
Behaviors exist because the neural circuits producing them have been
favored through natural selection
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E.g., homicide – exists today because related to past adaptive
behaviours
The Chemical Senses
Play a central role in motivated and emotional behaviour
Smell: mark territories, identify group members (urine; sweat)
Taste: identify foods ( food from non food, avoid poisons)
Old senses
Olfaction
Stimulus: Odorants (volatile chemicals), something that enters air and can
exist in air molecule. Ex: Can’t smell a desk, its not volatile
Organ: Olfactory epithelium *OE+(retina of the nose)
Contains receptor cells (olfactory sensory neurons) and support cells
Receptor cells send cilia into the olfactory mucosa
Airborne chemicals dissolve in the olfactory mucosa and interact with the
cilia
Activation of metabotropic receptors leads to the opening of sodium
channels and subsequent change in membrane potential
Smell things, enter OE, receptor cells detect volatile odorants with
cilia 9receptors on cilia specific to detect specific odorants), causes
change in membrane potential by opening sodium channels. Go to
olfactory bulb (extension of our brain?)
Olfaction
Olfactory cells project to the olfactory bulb, ending in tufts of dendrites
called glomeruli
In the olfactory bulbs, synapses are formed with mitral cells, which then
project to several areas of the forebrain
Olfactory Pathways
Olfactory nerve goes to areas of limbic system: Pyriform cortex, entorhinal
cortex, amygdala, hypothalamus, thalamus, and the orbitofrontal cortex
Smell is very emotional sense. Ex: Cinnamon, popcorn. May trigger strong
emotional reactions. Olfactory memory very compelling.
Note: no connection through thalamus for amygdala and pyriform cortex!
Project there directly. Why such a strong emotional component to smell.
Taste and smell= flavour
Accessory Olfactory System
Pheromone: Animals use as signalling mechanism
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