PSYC 2800 Study Guide - Final Guide: Olfactory Receptor Neuron, Olfactory Bulb, Olfactory Mucosa
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– 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=
– 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
– 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
– 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:
– 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
• 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 man’s 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
– 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
• Sexual stimuli not affect us when little but as we age, they have a different
– 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
– E.g., homicide – exists today because related to past adaptive
• 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
• 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
– 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?)
• Olfactory cells project to the olfactory bulb, ending in tufts of dendrites
• 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