9.031 Neural Basis of Learning and Memory: Lecture 2

Introduction to behavioral learning paradigms

avoidance learning - receive an unpleasant stimulus when the animal fails to make a response

- 2-sided shock chamber

learned helplessness - inescapable shock results in freezing

- used in context dependent fear conditioning

reward training - receive reinforcement when response is made

- shaping

escape - inevitable unpleasant stimulus continued unless response is made

punishment - receive an unpleasant stimulus when a response is made

can be subdivided into appetitive conditioning when the unconditioned stimulus is rewarding, or defensive conditioning if the stimulus is aversive.

Examples of classical conditioning paradigms are

• eyeblink/nictitating membrane
• taste aversion
• GSR

Discrimination learning - positive and negative stimuli, must identify the positive stimulus

lists

sequences

mazes

Paired associates - positive and negative stimuli.

radial maze

• stimulus/response preferences - some stimuli are more easily associated with some responses
• easy to jump or bar press for food; hard to condition to grooming or scratching
• - shock produced fear easily paired with visual/auditory stimuli; difficult to pair with taste
• - illness easily associated with taste but not visual/auditory stimuli
• - avoidance of shock easily paired with barrier jumping but not bar pressing.

• - easy for dogs to associate voice tone but not location

• - rats are good at radial maze but pigeons are poor, yet pigeons are good in open field tasks.
• - foraging patterns in rodents takes relative food quantity into consideration
• - instinctive drift observed in highly trained animals
• - imprinting

- study of behavior in relation to the environment; innate behavior

neuroethology - the study of the neural basis of innate behavior

• - echolocation in bats
• - electroreception in fish
• - sound localization in owls

• - activity dependent synaptic modification
• - presynaptic enhancement of release - facilitation/sensitization
• - presynaptic suppression of release - habituation
• - postsynaptic enhancement of response
• - alteration in membrane properties
• - enhancement of action potential transmission reliability
• - changes in neural excitability
• - structural changes

1) pharmacological manipulation

• agonists/antagonists
• systemic/local infusion

2) electrophysiology

• field potentials
• multiple unit activity
• single units
• ensemble activity

3) lesions

• resection/transection
• electrolytic - focal
• neurotoxic - selective (kill cells leaving fibers intact)

4) imaging

• PET - detection of small quantities of labelled compounds. radiolabelled glucose utilization
• MRI - differences in molecular composition - blood oxygenation
• optical dyes - electrical neural activity
• optical imaging of intrinsic signal - blood oxygenation

5) anatomy

• staining
• tracing
• electron microscopy (EM)
• metabolic labeling

6) genetic manipulation

• inducible (invertebrates)
• selective