Exam (elaborations) Neuroscience - Lecture notes for Exam 2 (2021)

Consumer Neuroscience Exam 2 Notes
Lecture 14: Simple Choice II
1. A model of making simple choices
2. How do we identify stimulus value signals?
3. Evidence for stimulus value signals in tasks
4. How does attention affect this process?
5. How are stimulus value signals formed?
6. Is there causal evidence to suggest the regions we identify are used in simple choice?
Chib et al. (2009)
 Demonstrated with: money, snacks, and trinkets
 Pre-scanning: Free response time/BDM auction
 During fMRI Scanning: 2 sec binary choice, 1-10 sec fixation
 Certain tasks can describe different tasks we might be interested in

However, certain simple consumer choice situations are not able to be captured by certain tasks
(ex. Choose between a food on left vs food on right side of screen)
 Foods are allowed to vary over trials; do we buy the apple or the orange?
Why is this a Complication Regarding Simple Choice?
 if SV (stimulus value) is coded as SVoption – SVreference, it’s not clear what is the option
and what is the reference
o with both changing constantly how do you evaluate apple vs orange
 attention is likely to fluctuate among different items that are evaluated over the course
of the decision
o this fluctuation can affect the SV computations (Relative decision value)
Krajbich et al. (2009)
- examples of simple choice with attention
Computational Model w/Attention




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, Lim et al. (2011)
- Relative Value Signals and Attention
- The ventromedial Pre-Frontal
Cortex (vmPFC) plays a role in
relative value signals and attention




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How is SV Computed?
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Evidence so far suggests vmPFC responses at decision time encode SV
- How are these SV signals encoded?
o Some Learning
 Subjects repeatedly face very similar stimuli, and have cached values for
items
o Some attribute integration
 Builds on the fact that stimuli can be complex bundles of simple attributes
 Simple ex. being (value apple = value sweetness + value calories + …)
Hare et al. (2009)
- Studied attribute integration by comparing how subjects valued health and taste


Causal Role of vmPFC?




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, - Correlational evidence that indicates the vmPFC is involved in encoding SV
o But observing this correlation is not enough to establish causality
- Gold Standard Test:
o Manipulate vmPFC activity at the time of choice
o Does this lead to changes in choices that are consistent with the model?
- Baumgartner et al. (2011)
o apply rTMS to dlPFC
o rTMS (repetitive transcranial magnetic stimulation; involves using a
magnet to target and stimulate certain areas of the brain)
 dlPFC (dorsolateral prefrontal cortex; gateway for directing cognitive
control because of its vast neural connections to virtually all sensory and
motor systems and subcortical structures, Miller 2000)
o immediately afterwards, they measure vmPFC activity during choices with fMRI
data
o Results find diminished activation in dlPFC and vmPFC
o Found changes in choice behavior to match diminished activation
- Lesions
o Lesion studies are effective at determining the role of vmPFC
o There are certain clinical populations that have damage in and around vmPFC
 Results in:
 Violation of transitivity
 Impairment in value maximization problems
o Evidence is not definitively conclusive
Chapter Summary
- Understanding simple choices is the foundation for understanding basic consumer
choices (relative valuations, action value, stimuli value, action cost)
- Testing neurocomputational models of choices gives evidence that vmPFC encodes SVs
at the time of choice
- However, there are still many open questions regarding the brain’s precise mechanisms
for making even simple choices
Lecture 15: Attention
Attention
- Our senses are bombarded with info everyday
- Our outer senses process this info but we are not consciously aware of all of it
- Our nervous system assigns relevance and value to information
o Is info novel/old? Intense/vague? Does it fit what we are already searching for?
There are 2 broad types of processing: bottom-up attention and top-down attention***
- Connection between the 2 is seen in everyday activities/actions (voluntary task switch)
Bottom-Up Attention (think random intrusive attention paid to sensory input)
- Sensory input can enter the mind by force (extremely bright, noisy, unexpected)


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, - Our lower senses are stimulated to such an extent that they produce effects higher up
in the processing system
- Properties of the stimulus can attract attention (bottom up cont’d)
- Not only vision
- Three Main characteristics of bottom-up attention
o Automatic
 Happens automatically as a response to certain events
o Fast
 Immediate response
o Non-voluntary
 Does not require one to purposefully focus their mind/attention
- Ex of studies: non-voluntarily identifying the one different pattern in a field due to
“noisy” attribute
- Neural Mechanisms of BUA
o Analysis restricted to visual system
 Visual cortex has cells that respond to things like movement, density,
contrast (if something moves then your eyes capture it)
 If a region stands out, our visual system detects this early on
 Visually salient information is detected first
 Primary Visual (sensory) cortex > Parietal > Frontal
o Some work suggests that a 2nd parallel route of BUA exists
 works by bypassing the primary sensory cortex with information being
sent to insular cortex and ACC (anterior cingulate cortex: located in
middle of frontal lobe, front of corpus callosum (L-R brain connector,
regulates emotions, task prep, error detection, executive functions) from
thalamus
 saliency (how notable something is) might be so important that it may
have evolved multiple routes to be processed
 Salient Processing may occur relatively fast or slow
 Fast saliency testing does not need detailed processing from
sensory cortices
Bottom-Up Attention can drive choice
- Milosavljevic et al. (2012)




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