PSYC453 - Midterm (Lectures)

Flashcards for lectures and presentations

Motivation

Psychological construct: energizing of behaviour in pursuit of a goal. Associated w/ direction, intensity and flexibility of behaviour.

What does motivation link together?

**External variables** (e.g., food) + **internal variables** (e.g., energy need) + **action/behaviour**

Homeostasis

Regulatory system to keep a particular physiological parameter constant.

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Change in the face of change so as to remain unchanged (e.g., stimuli trigger reflexes that reduce the stimulus).

Prototypic features of homestasis

System variable

Set point

Detectors

Correction mechanism

Hull’s drive reduction theory

Focuses on how motivation originates from biological needs or drives.

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E.g., We eat when we're hungry to reduce the discomfort that hunger causes within our bodies.

How does Homeostasis explain Motivation?

Drive Theories

(E.g., Deviation from physiological set point is aversive, eliciting drive to reinstate equilibrium)

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Natural Selection

(The need for physiological homeostasis is primary, and genes are selected if they increase our ability to maintain homeostasis).

Set point vs settling point

**Set point model:** physiological and genetic determinism, **Settling point model:** effects of social, nutritional & environmental factors.

Allostasis

Physiological regulation of changed states; Whereas homeostasis waits for errors and then corrects them, allostasis uses prior knowledge, both innate and learned, to prevent errors and minimize them.

Teitelbaum

Motivation must allow for flexible instrumental behaviour (e.g., We behave in anticipation of changes of homeostasis).

Wallace Craig

Motivated behaviors fall into two sequential

phases:

**Appetitive phase:** flexible approach behaviour towards the

motivational goal (pressing a lever to receive a reward)

**Consummatory phase:** stereotyped, species-typical pattern of movements (chewing and swallowing, licking and drinking water)

Epstein

3 criteria are need to distinguish true motivated behaviour:


1. **Flexible goal-directedness:** like Teitelbaum’s but requiring that strategies update when the goal changes
2. **Goal expectations:** evidence for declarative processes or goal predictions (refrigerator example)
3. **Affect:** receipt of the goal should elicit a hedonic reaction – the goal is actually something of value

Opponent process

The system wants to stay in equilibrium so generates an

opponent process to compensate for/oppose any deviation from equilibrium

(e.g., For any given hedonic a-process (leading to a

positive A-state), the body generates an opposing b-process (leading to a null or B state) to regain affective equilibrium

Bolles

Pair a neutral stimulus (S) w/ a hedonic stimulus (S\*)

Central nervous system

Brain and spinal cord, encapsulated w/ meninges

Peripheral nervous system

Somatic + Autonomic (parasympathetic & sympathetic) PNS

Spinal Cord

White matter tracks to and from the brain

Brain stem - Diencephalon

Cardiac and respiratory regulation

Cerebellum

Involved in classical conditioning and emotion regulation + refining movement

Midbrain - Limbic system

Thalamus: gateway for sensory info coming into brain

Cortex

Cerebrum, telencephalon

PNS routes

**Afferents** – white matter tracts travelling __**to**__ a particular brain region

**Efferents** – white matter tracts travelling __**from**__ a particular brain region

**Innervate** – white matter tracts which terminate on downstream structures such as brain regions and organs

Structure of a Neuron

• Cell body

Nucleus (contains DNA)

Grey Matter

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• Dendrites

Receive information from other neurons

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• Axon

Sends information

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• Myelin

Protects axon, speeds up communication

White Matter

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• Axon Terminals

Synapse onto dendrites of other neurons

Where neurotransmitters are released

Action potential

Input from other neurons bumps up voltage and can potentially surpass threshold, open voltage gates, then depolarization and sodium come into the cell = action potential. Then repolarizes when the gate stops sodium ions from coming in, potassium voltage-gated open, and potassium moves out of the cell. Cell goes below resting state because of the sodium channel block = hyperpolarization (can't fire until it's back at resting state) and then at resting state, block of na+ channel unblocks.

Basal Ganglia

* Movement + voluntary behaviour
* Impacted in Parkinson’s and Huntington’s Disease

(Striatum, caudate nucleus, putamen, nucleus accumbens, globus/ventral pallidum, subthalamic nucleus, substantia nigra)

(Cortico)Limbic System

Cortical: Prefrontal corex, orbitofrontal cortex

Subcortical: hippocampus, Nac, ventral pallidum, amygdala, hypothalamus, thalamus

Mesolimbic/Mesocorticolimbic Pathway

* Originates in the ventral tegmental area (dopamine neurons, part of midbrain)
* Projects to Nac, ventral pallidum, PFC
* Responsible for Motivation + Reward

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Hypothalamus

The primary interface of the brain with the visceral organs Helps the body maintain homeostasis


1. **Humoral response**: regulation of pituitary hormones
2. **Visceromotor response:** adjustment of the balance of the
sympathetic and parasympathetic outputs of the ANS
3. **Somatic motor response:** regulation of behavioural responses to adjust homeostasis

How do we study the brain?

Visualize activity/changes in the brain = **correlative** methods

Manipulation of activity within the brain = **causal** methods

Intracellular Electrophysiology

put electrode inside and outside cell, detect voltage inside and outside cell, determine whether neuron is active

Extracellular Electrophysiology

outside neuron, but very close, detect changes in current and whether they are firing action potentials

Calcium imaging

isolate at high resolution individual neurons

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use virus or transgenic animal to get indicator of calcium activity in a cell (calcium measure of cells activity)

Site-specific pharmacological infusion

Injection of pharmacological agonists/antagonists

into a region of interest

Genetic manipulation tools

**Transgenic organisms** – organisms with ‘extra’ DNA

inserted into the genome

**Knock-outs** – removal of genetic information from the genome

**Knock-ins** – addition of genetic information to a particular

location in the genome

Optogenetics

Allows the specific excitation or inhibition of neurons using

laser light

• Inserts photoreceptors into

neurons

Use of viruses for transgene insertion

**Type of viral vector** – this contains the genes required for the virus to function – to infect cells and get it’s vector transcribed

**The promoter** – sort of like an address, it tells the cell if the following gene should be transcribed – note, it is not used for coding the protein, just for identifying what the gene is

**Protein tool** – the transgene that the experimenter want to get into the cell

Cre-recombinase

Cre-Lox recombination is a site-specific recombinase technology, used to carry out deletions, insertions, translocations and inversions at specific sites in the DNA of cells. It allows the DNA modification to be targeted to a specific cell type or be triggered by a specific external stimulus

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***loxp surround gene that we may want to remove, cre removes/replaces it**

Anterograde transport

infect dendrites

Retrograde transport

infect cells that project to area of interest (axons)

Incentive salience hypothesis

Approach: Wanting, or incentive salience, is the incentive motivational value of a reward

Consumption: Liking, or hedonic value, is the affective experience of consummation

Alliesthesia

The relationship between the pleasure associated with a stimulus and the internal state of an organism.

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The increase in a stimulus' reward value because of its potential to move the body's physiological state toward homeostasis

Tolman’s maze

put rats on maze (3 groups)
1 group explored (no reward)
assess number of errors to get end
1 group from the beginning got a reward at the end of maze
1 group not reinforced then started reinforcement on day 11
learned faster to go to the end and better than always reinforced group

animals learning info about maze when exploring (no drive but seem to be learning anyways = latent learning)

Revaluation

a change in the hedonic or incentive value of a stimulus

A reduction in the hedonic value is referred to as devaluation (most common method)

Contingency theory

proposes that for learning to take place, a stimulus must provide the subject information about the likelihood that certain events will occur.

Instrumental behaviour terms

•**S-R: Stimulus – Response**; shorthand for reflexive or habitual response

•**R-O: Response – Outcome or (A-O: Action – Outcome)**; shorthand for goal-directed response

•**Variable interval (VI or RI, random interval) schedule:** The outcome is unavailable for lever-press until a randomized certain time passes

•**Variable ratio (VR or RR, random ratio) schedule:** the outcome is delivered after a randomized number of lever-presses

Loss of contingency

loss of ability to know that your actions are actually controlling the outcomes (outcome contingent upon your actions)

Striatum (dopamine has biggest effect)

Medium spiny neurons (MSNs): responsiv during movement, receive inputs from cortext, substanita nigra and interneurons and serotinergic pathways (inhibitory)

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Large aspin neurons (LA): receive inputs from thalamus

Direct pathway

Activation of D1-expressing MSNs tends to

release inhibition of motor (ventral lateral

thalamus

Indirect pathway

Activation of D2-expressing MSNs tends to

increase inhibition of motor (ventral

lateral thalamus

Phasic dopamine

*fast release of*

*dopamine leads to activation of D2*

*receptors*

Dorsomedial vs dorsolateral straitum

DMS = goal-directed actions

DLS = formation of habits: less neurons active at time of decision as behaviour becomes a habit (not thinking about where the goal is gonna be)

Dopamine as controlling motor function

if inhibited:

• Failure to orient to external stimuli

• Inability to initiate different types of behaviours

• Disruptions of typical locomotion patterns and

postures

Narcoleptics (dopamine antagonists)

lead to severely reduced pursuit of natural rewards, food, drink and sex; and reduced use of psychostimulants (even though they are able to pusue reward)

Reduction in reward pursuit could not be explained due to changes in motor function

Dopamine antagonism

reduces food consumption during free

feeding.

Animals were given bowls of 5 pellets every 36 seconds

Time to touch the first pellet was not affected by dopamine

antagonism, while the time to consume the pellets was

Incentive salience

motivation for rewards that is driven by both physiological state and previously learned associations about a reward cue. Similar to drug addiction, these cues can activate food-seeking and the development of compulsive habits.

Dopamine critical for reinforcement

incentive salience has to be learned da controls how motivating a stimulus is taking info about reward and finding any stimuli that predicted reward (retroactive)

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necessary to learn association btw stimuli + outcome, strengthens memory for association

Salience and reward prediction error:

neurons respond to surprising events and reward-related surprises

Incentive salience vs RPE

Incentive salience model focuses on explaining how predictive neutral stimuli come to motivate future actions – desire and ‘wanting’

Reward prediction error model focuses more on the process by which neutral stimuli (or states) become valued – how learning about value (or incentive salience) occurs

Dopamine antagonism

dopamine does not just attenuate the ability to respond, it appears to decrease motivation

RPE

The reward prediction error requires INCREASED activity during a positively valued surprise and DECREASED activity during a negatively valued surprise

Dopamine + motivation

It’s activated by sensory stimuli that are predictive of significant, or hedonically relevant outcomes.

It’s influenced by the current state of the animal

It appears to play a critical role in motivation of seeking rewards or goals.

James-Lang vs Cannon-Bard

The Cannon-Bard theory proposes that emotions and arousal occur at the same time (fear + heart rate spike). The James-Lange theory proposes the emotion is the result of arousal (heart rate spikes which makes us realize we are afraid).

Amygdala

• Involved in storage of emotional memories

• Necessary for fear conditioning and the

extinction of fear

• Involved in appetitive conditioning

Amygdala circuits

Central Amygdala: controls autonomic and

somatic responses to emotionally relevant

stimuli

Basolateral Amygdala: involved in formation

of memories of emotionally relevant stimuli

Limbic system in goal-directed behaviour

**Cortical areas**: involved in decision-making,

stimulus salience, contextual dependencies of

relevant stimuli, tracking of reward probabilities

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**Nucleus accumbens shell:** involved in feeding behaviour

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**Nucleus accumbens core:** Receives inputs from frontal

cortex and appears to be responsible for representing

motivationally relevant events

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**Ventral pallidum:** processes the hedonic value of stimuli

Papez take-away

Emotional reaction to stimuli must be learned. The limbic system is thought to be a critical system for learning about stimuli with emotional significance.