Procedural Memory System Flashcards
What can procedural memories involving the motor system be broken down into?
Acquisition of habits and skills.
Sensory-to-motor adaptations (involving adaptation of reflexes or Pavlovian conditioning).
What are procedural memories?
Habits and skills that become built into our motor system.
What is the primary motor cortex critical for?
The control of the force and flow of muscle movements
What is the premotor cortex critical for?
Movement preparation and sequencing
What are the two major subcortical structures that work with the primary and premotor cortices?
The striatum and the cerebellum
What do the striatum and the cerebellum feed into to connect back to the cortex?
The thalamus
What may the initial acquisition of procedural memories involve? When may this become consolidated into striatal circuits?
May initially involve a cortical store that during sleep becomes consolidated into striatal circuits
Who studied the effects of striatal lesions on the performance of rats in two variations of the radial arm maze?
Cook and Kessner (1988)
Who studied monkeys to demonstrate how habits and skills were encoded?
Kermadi and Joseph (1995)
Describe Kermadi and Joseph’s study
Trained monkeys to fixate on a central point, and then follow a sequence of three lights appearing to the left, right or above the fixation point.
Monkey then had to repeat this pattern by fixating on each location in the order the sequence was presented.
What did Kermadi and Joseph (1995) find about striatal cells in response to learned sequences?
There were cells in the striatum that would respond to one fixation location (e.g. ‘L’), but only when the monkey was going to make that response in a particular sequence (e.g. U, L, R).
The cell wouldn’t fire for L response in any sequence.
Where does the striatum receive input from?
The entire cortex
Where does the striatum project to, via the thalamus?
Premotor, motor and prefrontal association cortex
Where does the striatum have a very small projection to?
The brainstem
Where does the striatum not project to?
The spinal cord
What does the anatomy of the striatum suggest about its involvement in motor output?
Anatomy suggests that is not directly involved in controlling motor output
Why has it been suggested that the striatum might be involved in goal-oriented behaviour?
Because the striatum projects to regions involved in motivation and emotion (e.g. amygdala), and planning (PFC).
Where does the cerebellum receive input from?
Descending sensory and motor input from the cortex.
Sensory information direct from the spinal cord.
Major bi-directional connections between brain stem nuclei associated with spinal cord function.
Where does the cerebellum project to?
Primary motor and premotor cortices via the thalamus (but smaller projections compared to striatum).
How might the cerebellum guide reflex adaptations?
Compares motor plan from the premotor cortex with actual movements being made (from brainstem nuclei and spinal cord inputs) to compute an error signal. Then provides this information back up to the cortex to guide sensory-motor adaptations.
What does the anatomy of the cerebellar circuit suggest it may be involved in?
Execution of movements and acquisition of conditioned reflexes
Give an example of a well-studied conditioned reflex
The rabbit Pavlovian eye blink
Where does the cerebellum receive information about the tone from?
Auditory and pontine nuclei
Where does the cerebellum receive information about the air puff from?
The trigeminal system
Where does the association between the CS (tone) and US (air puff) occur within the cerebellum?
The interpositus nucleus
Where is the output for the CR (eye blink) generated in the cerebellum?
Red nucleus is the output for the interpositus nucleus.
Then via cranial motor nuclei to produce eye blink
How is the CR prevented?
By lesioning the interpositus nucleus.
Or protein synthesis block in the interpositus nucleus - thus blocking physical manifestation of the memory representation through LTP
Neither of these affect UR production (eye blink to corneal puff)
What happens when the red nucleus is reversibly inactivated, or the pathway between the interpositus and the red nucleus?
Temporary prevention of the CR, but upon recovery of the red nucleus (or pathway) the CR is elicited on every subsequent trial.
Shows that the CS-US association still builds up in the interpositus nucleus, but if the output is ina riveted then can’t produce CR.
Production of CR during training not necessary for conditioning
What happens if you reversibly inactivate the cerebellum?
Temporarily block production of the CR, however when activated again the CR is not elicited immediately - there is a gradual increase in the % of CRs elicited (i.e. the animal must learn the association).
Shows that the association is encoded within the cerebellum.
