Brain Circuit (Week 9/10)

Pavlovian conditioning is _____

2 Dimensional

2D categories for Pavlov

Stimulus-action event (Excitatory/inhibitory)

Motivation property event (Appetitive/aversive)

4 types of Pavlov conditioning

Appetitve excitatory = Stimulus present predicts arrival of food

Appetitive inhibitory = stimulus prediction omission of food

Aversive excitatory = Stimulus predicts electric shock

Aversive inhibitory = Stimulus predicts omission of shock

Types of Pavlovian CS

Discrete CS = have start & end —> ie. auditory, tone, light

Context CS = no. imminent start/end —> ie. conditioning chambers

CS that has start & end

Discrete CS

CS w. no end/start

Context US

How to distinguish discrete and context CS

Discrete = Test discrete CS in distinct chamber

Context = test in diff contexts (ABA, ABC)

At what points of time should the brain be manipulated to study acquisition, consolidation & retrieval

Acquisition = Before fear cond/ext

Consolidation = Just after fear cond/ext

Retrieval = Before test

Process to how brain forms association (3 steps)

1. Process discrete CS individually

2. Process US

3. Combine info of CS & US —> form CAUSAL relo —> CS-US forming CR

Brain region for CS modality: auditory CS

Auditory thalamus + auditory cortex

Brain region for CS modality: visual CS

Visual thalamus + visual cortex

Brain region for CS modality: context CS

Hippocampus

Hippocampus related to ____ CS

Context

Auditory/visual thalamus + cortex related to ____ CS

Auditory/visual CS

Difference between thalamus + cortex

Thalamus = process info more rapidly

Cortex = Provides more detailed info

____ processes info more rapidly

Thalamus

y

____ provides more detailed info than ____

Cortex, thalamus

Where is the hippocampus found

Medial temporal lobe

Medial temporal lobe holds _____ (2)

Hippocampus & amygdala

What happens when the hippocampus is silenced (via lesions) pre/post fear conditioning?

Pre-cond = No effect

Post-cond = decreased freezing

What conclusion could be made about the hippocampus (fear cond)

Pre-cond = prevent configural representation forming (prefer to use)

• Lead to process elements independently —> Thus equiv freezing to controls

• Only contextual conditioning

Post-cond = allowed configural representation formation

• Post-lesion prevented RETRIEVAL

• Thus no fear displayed

Configural rerpresentation

Elements of a context are linked and established as a “configural representation” of the space/context

Advantages fo configural representations (2)

Pattern completion —> enable retrieval all elements of context by perceiving a few

Reduces cog load

Which brain region does the dual-process theory occur

Hippocampus

Dual process theory of the hippocampus 3 assumptions

1. Context can be processed as separate elemental features in relevant elemental areas (ie. auditory, visual cortex/thalamus)

2. Context can be processed via configural representation

3. By default, brain favours configural representations (<cog. load)

Amygdala found in ____

Medial temporal lobe

Subnuclei of amygdala (2)

Basolateral Amygdala & Central Nucleus

Basolateral Amygdala subnuclei (BBL)

Basolateral Amygdala

Basomedial Amygdala

Lateral Amygdala

Lateral Amygdala purpose in fear conditioning

Receives discrete cue projections (auditory & visual) for fear cond

_____ receives discrete cue projections (auditory & visual) for fear cond

Lateral Amygdala

Basal Amygdala purpose in fear conditioning

Context fear conditioning —> receive hippocampus projections

____ receive hippocampus projections for fear conditioning

Basal Amygdala

Muscimol drug

Receptor agonist of GABA

Receptor agonist of GABA

Muscimol drug

GABA

Inhibitor of neuronal activity

Inhibitor of neuronal activity (receptor)

GABA

BLA inactivation findings

BLA needed for:

• Acquisition of discrete cues + context

• Retrieval/expression of fear memory

NDMAr purpose

Triggers memory formation (supports learning)

_____ Triggers memory formation

NDMAr

Ifenprodil drug

Blocks NDMAr —> wthin BLA

____ blocks NDMA

Ifenprodil

NDMA receptor inhibited pre/post conditioning results

Pre-cond = Impaired acquisition

• Thus NDMA needed for ACQUISITION

Post-cond = No effect (no retrieval impairments)

What happens during consolidation (post-conditioning)

Protein synthesis to form CS-US pairings

Purpose of protein synthesis

Implementation of structural + physiological changes in neuron supporting a memory

Anisomycin

Blocks protein synthesis

_____ blocks protein synthesis

Animycin

Protein Synthesis Inhibition ___ conditioning results (increasing dosage)

Post —> consolidation = protein synth —> occur post-cond

>impairement of fear w. dosage

Protein synth is needed for CONSOLIDATION

Memory Engram

Phys + biochem changes in brain representing storage of specific memory

______ = Phys + biochem changes in brain representing storage of specific memory

Memory engram

What happens to neurons during memory engrams

Event activates neuronal ensemble (specific pop of neurons) that undergo physiological change

Change enable memory formation + storage

What does retrieval of memory involve (engrams)

Reactivation of specific neuronal ensemble

____ is the reactivation of specific neuronal ensemble

Retrieval

How are neuronal ensembles manipulated?

1. Condition in context A —> see which neuronal ensemble is activated

2. Tag activated neuronal ensemble w. OPSINS

3. Place in context A (test) —> should see neuronal ensemble light up

4. Place in context B —> Able to manipulate via optogenetics

   • Able to see fear in context A in B —> usually won’t happen

What genetic tool was used for neuronal ensemble manipulation

Optogenetics

What did fear engrams (tagging) support the BLA subnuclei’s indiv purposes?

Basal amyg = lit up during context fear

• Ie. freeze more in high fear context

Amygdala = lit up during discrete fear

• Freeze more from auditory cues

What did fear engram tagging suggest overall

Fear memory engrams are present within BLA

• Involved in acquisition, consolidation & retrieval of memories

Muscimol drug used to inhibit GABA in:

BLA & CeA (Central nucleus Amygdala) & Interlimbic Cortex

Ifenprodil used to inhibit

NDMA receptors in BLA

Anisomycin used to inhibit

Protein synthesis

CeA inhibition findings pre cond/testing:

Pre-cond = Little fear

• Couldn’t form memory

Pre-testing = little fear

• Couldn’t retrieve/express memory

CeA needed for ACQUISITION + RETRIEVAL

CeA roles

Controlled by BLA + contribute to acquisition & retrieval of fear memories

Amygdala lesion but intact hippocampi?

Can process contextual, not discrete CS

• Ie. don’t learn to fear auditory or visual, can process factual info

Whst brain region is hyperactive for anxiety disorders? Why?

Amygdala

Pavlovian fear cond increases amyg activity

CeA subnucleis

Lateral & medial

What are all the brain parts related to Pavlovian Fear Conditioning

Bonus: Purposes of each if can remember

Amygdala (2 subs, 3 and 2 extra sub respectively)

NDMA receptors

Protein synth

Cortex + thalamus (discrete)

Hippocampus (context)

Goal directed behaviour

Action based on its consequences & have goal

Help learn + update new skills

Cognitively demanding

Habitual behaviour

Little thinking/automatic behav

Little cog oversight

Help refine skills —> esp motor (ie. playing piano)

Can we look at performance to distinguish goal & habitual behav - why?

No, both forms promote actions & responses

Causality & value —> difference between goal & habitual

Goal

• Have causal relo w. outcome

• Deem outcome w. VALUE

• Thus sensitve to change in causality/value

Habitual

• Insensitive to change —> no cause or value

• Can obtain via overtraining

Schedules of reinforcement difference between goal & habitual

Ratio = no. action correlate w. no. delivered outcomes —> goal-directed

Interval = time interval dictates outcome delivery —> habitual

What is contingency degradation used for?

Used to test causality in instrumental cond

What is contingency degradation & probabilities

Tests for causality

Initially learn 2 positive contingencies (lever = outcome)

• Prob. higher for CS-US than CS-noUS when press lever

Then freely deliver outcome sometimes during instrumental conditioning

• Equal prob. in CS-US & CS-noUS

  • Lead to causality loss

What is the probability of CS-US & CS-noUS in positive contingency learning

CS-US higher than CS-noUS

What is the probability of CS-US & CS-noUS in positive contingency degradation

Equal chance of both

Contingency degradation effect

Perform non-degraded action more than degraded action

• Larger for goal-directed indiv (loss of causality)

• Smaller for habituation

Is the contingency degradation effection larger for goal or habituation & why

Goal —> loss of causality

Habituation doesn’t need any causality to begin with

Outcome devaluation purpose

Test whether goal directed behav. is influenced by value

• Cause one lever to be more “valued”

Types of outcome devaluation

Sensory-specific satiety & conditioned taste aversion

Sensory-specific satiety

Gives hungry animal free access to one food for brief time period

• Gorge themselves w. outcome (devaluing)

_____ gives hungry animal free access to one food for brief time perio

Sensory-specific satiety

Conditioned Taste-Aversion

Outcome given freely too

• But injected w. LITHIUM CHLORIDE —> make mildly sick

• Repeated process (associate food w. sickness)

• Takes away food appeal

_____ gives outcome freely, then makes mildly sick using ____

Conditioned taste aversion, lithium chloride

Lithium chloride use:

Outcome devaluation

• Make sick & devalue an outcome

Tests for instrumental conditioning are extinction tests because:

Reflect animal’s knowledge of what was encoded during training

Specific satiety testing between 2,5 & 20 days results & type of behav

2-5 days show devaluations effect

• More response to “valued” than devalued

• GOAL-DIRECTED

20 days showed no devaluation effect

• Equiv response between both lever outcomes

• HABITUATION

Which brain sections are related to goal-directed behaviour:

Amygdala & prelimbic cortex’s: medial prefrontal + dorsal striatum

Prelimbic cortex & specific satiety test & pre/post lesions

Pre-cond w. lesions = show habituation

• Therefore show prelimbic cortex necessary for ACQUISITION of value

Post-cond w. lesions = show outcome devaluation

• Not necessary for consolidation

Is the prelimbic cortex related to goal directed/habitual behaviour

Goal-dirercted

Prelimbic cortex relevance in goal-directed behaviour

Acquisition of value

Striatum relevance to humans

Represents instrumental conditioning in humans via CAUDATE

posterior vs anterior lesions & specific satiety

Lesions for either posterior or anterior were presented pre-cond

pDMS showed indifference between levers

pDMS needed for acquisition of goal-oriented actions

Further looking into pDMS (pt2) pre & post-cond lesion for specific satiety

Pre-training = shows insensitive to devaluation (equal pressing)

Post-training = shows insensitive to devaluation (equal pressing)

• Therefore important for RETRIEVAL OF GOAL-DRECTED ACTIONS

BLA (basolateral amygdala) pre-cond lesions results for specific satiety

Insensitive to specific satiety

• Relevant for ACQUISITION

BLA (pt2) specific satiety (pre & post devaluation)

Pre-devaluation = showed insensitive to devaluation

Post-devaluation = showed sensitive to devaluation

• Results higher than vehicle’s valued lever

Overall imply that BLA is important for processing changes in assignment of value

• Not really involved in encoding contingencies

Which brain network involved in habitual actions

Corticostriatal network (Infralimbic cortex, dorsalateral striatum & central amygdala)

Brain parts involved in habitual actions (ICDS)

Infralimbic cortex

Dorsalateral striatum

Infralimbic Cortex (IL) vs Prelimbic Cortex (PL) in outcome devaluation

Pre-training lesions

• 2 diff contexts trained in (overtrained and undertrained w. diff outcomes)

Undertrained

• IL = show devaluation effect

• PL = equal responding (insensitive)

  • PL have role in ACQUISITION OF GOAL DIRECTED ACTIONS

Overtrained

• IL = equal responding (insensitive)

  • IL have role in ACQUISITION OF HABITUAL ACTIONS

• PL = devaluation effect

Interlimbic Cortex’s role in instrumental conditioning

Needed for acquisition & retrieval of habitual actions

Prelimbic cortex’s role in instrumental conditioning

Needed for acquisition of goal directed action

Interlimbic cortex study (devaluation)

Post-devaluation (muscimol infusion) of overtrained rats

• Sensitive to outcome devaluation (despite overtraining)

IL needed for retrieval of habitual actions