chapter 7 Flashcards
Learning as an Adaptation in Juncos and increased feeding experiment
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Research question:
Does age affect feeding efficiency? (Sullivan 1988)
Does you increased experience (age) affect feeding efficiency.
Hypothesis:
As birds age they should have more experience handling food
Prediction:
Older birds should handle food faster than younger birds
Methods:
Mealworms cut into small or large pieces
Smaller pieces easier to mandibulate
Handling the food, preparing it
Recorded handling times (time from first contact until consumption) of recently fledged, young, and older juveniles, as well as adults
From first contact to when you actually eat it
Results
X axis just means as you get older
Looked at 4 different age groups
As you get older, the handling time will go down, meaning you get better
The efficiency was measured in time and profitability
Profitability is calculated to estimate how much energy the animals were able to extract from the food items (jules/s)
As you go across the age groups, the handling time goes down and the profitability goes up and you can infer that the survivability is increased
Spending less time on a food item while also maximizing the profit
Yes having experience is a good thing
Simplest Forms of Learning
Habituation is the simplest form of learning
Habituation, Environmental Stimulus, Response definitions
Habituation: reduction of response to a stimulus over time
Environmental stimulus: anything in the environment that elicits a response
Response: reaction to a stimulus
Dear Enemy Hypothesis
Dear Enemy Hypothesis: once another male comes around and begins the establish his territory, he is still a rival but don’t spend as much time being aggressive
The focal males response of aggression goes down and this response becomes habituated
very costly to be so aggressive all the time, if you are spending all time being aggressive, when are you going to attract mates, feeding, set up territory
Territorial Frogs and Dear Enemy Hypothesis Experiment
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Research Question:
Does the dear enemy hypothesis explain aggression in territorial green frogs? (Owen & Perrill 1998)
Hypothesis:
The level of aggression to a conspecific will vary with familiarity due to habituation
Conspecific = member of the same species
Mechanism allowing this to occur is habituation
Habituation is a decreased in response over time so it’s expected to see a decreasing trend, but sometimes the data shows an increase
Prediction:
There should be a decrease in their response to a new rival’s vocalization after an initial aggressive response
Methods:
Studied males at four ponds
Created synthesized calls of two males
Dominant frequency of 350Hz
Dominant frequency of 450Hz
Playback of calls from speakers 1-2 m from focal calling male
Recorded focal male response calls & movements toward speaker
The researchers listened to the vocalization and are produced at a frequency (Hz)
They wanted to simulate an intruder → you can know there is an intruder by listening to the intruders vocals
2 types of frequencies used
Dominant = the one they focused on 350 Hz and 450 Hz
The speaker was placed in a particular territory
Played the primary frequency back to the focal male, measured the focal males response to the calls
They can control the call because it is not alive animal that they are using
Animals response to 350 Hz frequency
The x axis it time
When looking at habituation we are looking at change in behavior over time
Y axis is the number of movements by the focal male
Trend: as time increases, and the sounds is continuously heard, the movement decreases
He is becoming habituated to the sound
As time increases, the 350 Hz was played and then turned off, and then there was a second broadcast which resulted in a little rebound in movement but eventually, habituation reoccurred
Second (450 Hz) had the same results as 350 Hz
Want to be able to measure habituation in different ways
Data can sometimes have an upward trend which may also indicate habituation
In the graph below, the y axis dominant frequency of the focal male is being measured (what is being heard most of the time, what frequency is most common)
The x axis is categories
Base represent baseline → when there is no manipulation by the researchers, how is the animal behaving.
450-1 → when the synthesized call is played at 450 Hz what is the response of the focal male
When he starts to hear a synthesized called at 450, the frequency of his own vocalization changes, it gets a little lower
The number 1 is the first time that the 450 is played
End -1 → a point near the end of the time where the 450 Hz is being played
Near the end of the 450 being played, there is an increase in the call frequency of the focal males which is habituation, close to baseline
Rest → no synthesized called being played, close to baseline
450 -2 → the two means this is the second time the synthesized call is played after a period of rest. There is a decrease in the focal male frequency released
End - 2 → there is a rebound, indication of habituation
350 Hz → synthesized frequency played and the vocalization of the male goes down in frequency
Note that when the vocalization goes down, it is a dominance call, more aggressive
Critical period is the category
Neuroscience of Learning
Assess if learning is taking place by looking at the quantity of neural chemicals in a particular part of the brain
Increase or decrease
Impriting
Imprinting is very fast learning
Exposure to a stimulus very early in life and the learning that occurs is follow the stimulus around
Usually is the mother, she offers nutrition and protection
Follow a stimulus that was there at the time at birth
Ducks followed boots, imprinted on the boots
Imprinting is non discriminatory, does not have to be a mother
Neuroscience of Learning Experiment on Imprinting
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Research question:
Is the release of neurotransmitters from the presynaptic neuron associated with imprinting learning? (Meredith et al. 2004)
Methods:
Control Vs. Exp group
- the experimental chicks were presented an red box or blue cylinder when they were young.
- the control chicks were not exposed to the a colour.
Trained on running wheel
-the animals were trained to run on the wheel
Measured movement toward stimulus was recorded
- the animals where then presented with either red boxes or blue cylinders and the movements were recorded.
- the animals had a higher preference score on the imprinted objects.
- the control animals showed very little movement when presented with a stimulus.
Measured amino acid transmitters in intermediate and medial portions of hyperstriatum ventrale (IMHV)
- the preference scores correlated with the release of GABA
- there was also increase in glutamate release
Preference score
running time towards the imprinted object in a fixed time period / total running time to both object
preference score was calculated by placing two objects in front of the chick on the wheel
a preference score below 50 is just chance, a score above 50 shows preference
Memory
Neural Plasticity
Dendritic Spines
definition
Memory: retention of learned experiences
Neural plasticity: structural changes in the brain
Dendritic spines: found on dendrites of neurons
measure if memory has occured by measuring the change in structure in the brain by measuring the number of dendritic spines on the neurons
Dendritic spines in mice experiment
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Research question: Is dendritic spine formation associated with learning in mice? (Yang et al. 2009)
The spines change in relation to learning that occurs
Methods:
Control: no training
Experimental: mice trained to run on a rotorod
Measure the formation of new dendritic spines
Connect wheel to a motor so you can set acceleration
As the mouse starts to be better equipped, the amount of time the mouse is spending on the wheel increases
Are there changes in neuroplasticity associated with learning?
Measure the number of dendritic spines
In the control there is no training, in the experimental group, there is training on how to run on it
Results
If there is training, the number of dendritic spines increase in the motor cortex
Conclusion: formation of new dendritic spines is associated with learning
There are 3 control treatments
No training
Non acceleration → wheel is moving but the speed remains the same
Barrel cortex → part of the brain in the mouse that captures information related to sense of touch
This area is not associated with motor learning
In the first two controls, they measured dendritic spines in motor areas and in the third control they took information from different areas in the brain (the barrel cortex) which is part of the somatosensory system
Are other parts of the brain, not connected to motor learning, is there a change in dendritic spines
Training → acceleration, speed increases over time, the rod speed increases overtime
They looked at young animals and old animals, different spines occurring in young vs. old animals
The young training = most dendritic spine formation
In the other young, there is some spines but not as much
In the adults, the pattern is the same but there is not as much dendritic spine formation
In the motor area, there is more dendritic spine formation from training than in the other control groups
Part 2 of experiment
The technique the researchers used allowed the animals to continue living, using an imaging technique, they did not have to kill the animal
The experiment continued on and used the young animals
Some animals stopped training, some continued with the same training regime and a final group got a new training regime
New training, wheel is moving backwards now
There is increased spines in the changed regime
This shows that the system is very flexible
Note a decrease in number of spines just means that the experience is not really changing
The expression of change in dendritic spines is more apparent in younger animals
If the information is coded in the brain well, there is less forgetting
Decrease in dendritic spines does not mean that there is a loss of information
Cache
Episodic Memory
Definition
Cache: storage of foods
Even within a family, there are some animals that cache a lot vs. some that do not, there is a lot of variability in the caching behavior
Hippocampus function
Spatial memory is associated with the hippocampus (hippocampal formation)
Animals that cache very heavily have a larger hippocampus compared to those that do not cache as frequently
Pavlovian Conditioning in Japanese Quail Experiment
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Research question: How does learning affect fitness? (Adkins-Regan & MacKillop 2003)
Hypothesis: Individuals can benefit by learning to associate environmental cues (a place) with mating opportunities
If mating were to occur, it is best to go to a certain part of the environment where mating often occurs
Prediction: Reproductive success will be higher in the condition where individuals learned that mating often occurs
Methods
Trial = days
Day 6 is test 1, day 7 is test 2
Create 2 environments, one with a mating opportunity, one without
Cage A and B have different environments
Cage A made of plexiglass
Cage B made of wood
The circled cages mean that there is a mating opportunity
In cage B there is no …..
In the training, the males are exposed to the environments, one of which allows mating, one that does not
Test 1: there is training
Take a male, introduce female allow them to mate in CS+ environment
Male learned that in the CS+ there is a mating opportunity
The male then introduced into the CS- and there is mating
Based on the prior environment (trial stage) how does it impact the mating in the current environment (CS+ or CS-)
The test male bird will be conditioned in Cage A and Cage B for 5 trial days
During test 1, you put him in the learned mating cage and measure eggs
Put same guy into learned no mating cage, but now there is a female, they mate and see the number of eggs
Results: there are more eggs in the CS+
Depending on the first environment will affect the fitness
If they were in the Cage A for the trial (where allowed to mate with the females) and in Cage B were not allowed to mate, they will produce more eggs in Cage A in the test days
Same experiment was done in females and showed similar results
Conclusion: Pavlovian conditioning can affect fitness
Learning Curve in Macaques
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Research question:
How quickly can individuals learn to overcome an innate preference?
Methods:
Training:
Offered six subjects choice of one or four peanut halves
Got either 4 peanut halfs or 1 peanut half
If choose one, subject received four peanut halves
If chose four, subject received one peanut half
If you select 4, the reward was not as much (if you chose 4, you actually got 1, if you chose 1 you actually get 4)
4 loonies vs. 1 five dollar bill → takes kids a while to figure out
Measured how quickly individuals learned to select the smaller quantity
Shows different subjects, the percentage of error went down
Some were faster learners than others
A lot of variation in learning
How fast they were able to override their leaning
