Post on 19-Dec-2015
Elicited or Unconditioned Behavior Occurs without past experience Modifiable with experience (examples:
habituation and sensitization
Some Types of Elicited Behaviour An eliciting or unconditioned stimulus elicits a
response without any prior learning Types of Elicited Behaviour
Simple Reflex Orienting Reflex Taxis (taxes) Kinesis (kineses) Fixed/Modal Action Patterns
FAPs/MAPs
Sequence of behaviors directed at the eliciting (sign or releasing) stimulus
Sometimes requires underlying drive (hydraulic model)
Vigor of response depends on how closely the sign stimulus corresponds to the ideal stimulus (e.g., cute baby) Small (non-ideal) Normal (ideal) Supernormal (exaggerated ideal)
Supernormal stimulusAn accurate 3-dimensional model of a herring gull's
head (a), and a 'supernormal' bill (b).
Supernormal stimulus
Supernormal stimulus?
versus
1950s 1990s
Habituation
a simple type of learning which is shown by a change in elicited behaviour over trials
defined as a reduction in responsiveness (frequency, magnitude) over successive trials
sometimes short-lasting and sometimes long lasting
Habituation-One Type of Modifiability
Eric Kandel and Aplysia
Kandel`s Experiments
Touch Siphon
GillWithdrawal
Habituation
touch
gill withdrawal
Forms of Habituation
Short-Term lasts only a few minutes best if stimulus applied at short intervals (2-s)
Long-Term lasts weeks best if stimulus applied at longer intervals (30-s)
Simplified Circuit
What’s the Mechanism of Short-term?
loss of skinsensitivity
fatigue
decrease in motorsynapse
decreases in synaptic transmission
Pinsker et al., (1970) Science 167:1740
Evoked
Spontaneous
Not Muscle Fatigue
What’s the Mechanism of Short-term?
loss of skinsensitivity
fatigue
decrease in motorsynapse
decreases in synaptic transmission
Not Motor Synapse
skin
MN
SN
gillrecord
Kupfermann et al., (1970) Science 167:1743
electrical
After
Before
What’s the Mechanism of Short-term?
loss of skinsensitivity
fatigue
decrease in motorsynapse
decreases in synaptic transmission
Not Skin Sensitivity
skin
touch
MN
SN
gill
record MNactivity to assay
habituation
Kupfermann et al., (1970) Science 167:1743
Stage 1
Not Skin Sensitivity
Kupfermann et al., (1970) Science 167:1743
skin
touch
MN
SN
gill
record MNactivity to assay
habituation
block
What’s the Mechanism of Short-term?
loss of skinsensitivity
fatigue
decrease in motorsynapse
decreases in synaptic transmission
Mechanism of Short-term Habituation
Decrease in neurotransmitterreleased at the synapse with both the motor neuron and theinterneuron!
Mechanism of Long-Term Habituation
Change in the number of synapses!
Some Properties of Habituated Responses
1. Spontaneous Recovery 2. Dishabituation3. Generalization
Hi
Lo
Response
Number of Presentations
Spontaneous Recovery
Time Passes
Stimulus
Hi
Lo
Response
Number of Presentations
Dishabituation
Novel Event
(no timepasses)
Stimulus
HabituationDishabituation
Generalization
Sensitization- Another Type of Modifiability enhanced response to a “benign” stimulus after
exposure to a “noxious” one (most common) for example, startle
enhanced response after repeated presentations of a “not so benign” stimulus (less common) for example, kindling
RatStartle
Human Startle
Kindling
repeated stimulation of hippocampal cells increases responsiveness
after being sensitized, very little stimulation is required to produce the seizures
related to epilepsy
Dual Process Theory
1. S-R System: Habituation
2. State System: Sensitization
Competition between two separate processes
Examples
+
-
S
H
NET
+
-
S
H
NET
Trials Trials
Conditions Favouring Habituation
1. Calm organism2. Shorter interstimulus intervals3. Less variable interstimulus intervals4. Low intensity5. Less complexity6. More trials
Interstimulus Interval
Complexity
Trials
LookingTime
Imagine……… Kendra is an overly anxious person. She worries
about the smallest things. Some examples of the unpleasant symptoms she experiences include excessive sweating, heart palpitations, and a fitful sleep. Her anxiety places her at risk for depression, heart disease, and diabetes. A genetic test reveals Kendra has a vulnerability in the promoter region of her serotonin transporter gene. Her doctor tells her that if her mother had been more loving and attentive when Kendra was younger, she might have been calmer. The doctor maintains experience can program calmness, and calmness acquired by experience is inheritable.
Gene Expression-A third Type of Modifiability Genes affect bodily processes, including emotional
regulation Two copies of the “short” version of a promoter for the
serotonin transporter gene is a risk factor
Maternal Behavior
licking and grooming (LG) and arched-back nursing (ABN)
Low LG-ABN mothers
High LG-ABN mothers
Attentive Mothering Licking and arched-back nursing by mother
an immediate “calming” effect on baby rats in the first week after birth
a long-term reduction in stress responsiveness the promoter for the short version of serotonin
transporter gene is “switched on” by attentive mothering so, a vulnerable pup with two short copies of the
promoter for the serotonin transporter gene is cured by its mother’s licking (short gene works better)
this environmental effect is passed along to the pup’s own offspring
Brain of Vulnerable Baby Rat
high LG-ABN mother
short gene expressed
less anxiety
Cross-fostering Studies
Imagine………
Kendra’s doctor gives her a prescription for a pill that will promote the activity of the malfunctioning gene. No other therapy is necessary. Kendra’s children inherit the faulty gene, but its function is enhanced.