Habit Learning Flashcards
(28 cards)
what is habit
repeated performance of instrumental actions in a stereotyped fashion
gradual formation of certainty and predictability
stimulis-response - inflexible
means of dealing with repetition - free attention for alt means
how long does it take for a habit to be learned
must build confidence in assoc between a-o
if environment is stable enough then over time learning becomes habitual
repeated in the same environment over a long period of time
a-o shifts vi continued training from the consequence to the antecedent = s-r
how do you know when a behaviour is habitual
it becomes s-r oriented - no longer impacted by its outcome
insensitive to devlautaion
where are a-o associations learnt
VS
involved in limbic and reward processing
form associations between an action and its consequences
where are S-R associations implemented
DS
sensorimotor, beh control/cog control processes
involved in motor planning and action selection in S-R associations
how do a-o become s-r?
DA innervation of the striatum in the nigrostriatal pathway
haber
input from the midbrain innervating the striatum - connects striatal subdivisions in habit formation
what are reinforcement schedules
important to investigate a habit learning
allow experience of uncertainty and delay
intervals make it faster for a habit to be learned - contingency between a response and its outcome is weakened
define continuous reinforcement schedule
always recieve the reward immediately following an action
define fixed interval reinforcement schedule
recieve the reward after a delay (must be tolerable for the rat)
alwas after a delay - learn eventually how long to wait for it
define random interval reinforcement schedule
reciept of the reward following a delay is never exactly certain
delay time averages out over cumulated trials
makes habit learning faster because it seperates the association between the VS and the DS - action performed continuously following the cue but the reciept of the reward can never be completely predicted
role of interval schedules in temporal discounting
random interval makes the rat discount the reward as account of its delay period - perform the action but longer delay = not as valuable as one was
behaviour becomes more s-r oriented than a-o oriented
contingency by an action and its outcome is gradually weakened
dissoc motor action beh from the valued reward so faster to become habitual due to heightened exploitation of the DL > VMS
means to devalue a reward
satiety (faure)
aversion (yin et al)
yin et al
method
rats with leisons in the DLS (1) or DMS (2) prior to training (using NMDA infusions to damage)
- magazine train sucrose to lever
- different reinforcement schedules
- lithium chloride devaluation
- 3 daily sessions of sucrose and lithium chloride or saline - extinction test
yin et al
hyp
sham rat (no lesion to the DLS) will not reduce their response following devaluation - habit
DLS leisons be rapidly aversed by lithium chloride
- unable to assoc VS - DLS to make a-o s-r oriented
yin et al
results
devaluation- both leisoned and sham rats gradually reduced their sucrose consumption over 3days when presented with the averisve lithium chloride
extinction test:
after devaluation - extinction test on the levers
devaluation did not affect responding in the sham or DMS groups but effected those with selective lesions to the DLS - DLS sig reduced lever pressing in extinction after devaluation
yin et al
explanation
DLS did nto form a habit and therefore remained sensitive to the devaluation of the reward
DMS and sham rats still able to form a habit - do not link the action to its consequences and not devalue
s-r and a-o processes can operate independently to control instrumental performance
role of DLS
recieved excitatory projections from sensorimotor cortices and influence of motor systems via projections to brainstem and thalamocortical pathways
+ somatotopically organised with the cortex
DLS rats able to acquire and maintain responding to outcome devaluation - responses not mediated by S-R learning
dissociation between goal-directed and habit learning systems
how does a habit become a habit
haber et al
nigrostriatal pathway
transfer of information between VS to DLS based on connectivity between the striatal subdivisions using descending glutamatergic projections to the SN and ascending DA projections from the SN topographically from the VMS to the DLS
SN innervates, following medial/ventral input, via DA terminals, the striatum slightly more dorsally than before -
positive ascending spiral shifts representations via VMS innervation towrds motor/exec circuits (DLS)
haber et al
how investigate the nigrostriatal pathway
PRIMATES
retrograde and anterograde tracing
- placed into striatal regions associated with limbic, cognitive, or motor corticostriatal pathways
- allow the detailed descriptions of neuronal projections from a single neuron or a defined population of neurons
-“mapping” of connections between neurons in a particular structure
nigrostriatal pathway
ASCENDING FEED-FORWARD CORTICOSTRIATAL LOOP
interface between striatal regions via the midbrain DA from SN and VTA - organized in an ascending spiral interconnecting different functional regions of the striatum
functional gradient from assoc limbic to motor domains by virtue of the striatonigrostriatal circuit
glutamatergic projections from shell target the VTA and vmSN
Midbrain projections from the VTA to the shell form a
“closed,” reciprocal SNS loop
Projections from the medial SN feedforward to the core forming the first part of a spiral which continues
through the SNS projections with pathways originating in the core and projecting more dorsally
ventral striatal regions influence more dorsal striatal regions via spiraling SNS projection
parkinsons and the nigrostriatal pathway
degeneration of DA neurons in SN lead to progressive DA depletion
assoc w/ motor impairments, cog deficits, and habit learning deficiencies
SN cannot innervate more dorsal regions of the striatum
dependent on disease severity and task demands
faure et al hypothesis
DA dysfunction impact habit learning?
investigate the role of DA in the nigrostriatal pathway and its impact in habit learning in rats
faure et al
method
asses S-R status of instrumental performance using satiety-specific devaluation procedure of reward following overtraining
skinner boxes
stereotaxic injections of 6-hydroxydopamine to striatum - interacts with transcending DA neurons, attaches to DA receptors and induces partial retrograe bilat degeneration of nigrostriatal path
train on two responses: lever press and chain pull
chain more complicated - longer to learn /form a habit
faure et al
devaluation procedure
use extinction paradigm
given adlib subcrose pellets or food pellets
give access to reward ad lib - no longer desire the receipt of the reward in the instrumental procedure (UNLESS HABIT)
