Cerebellum & Classical Conditioning Flashcards
what is a simple form of learning studied to understand the underlying brain changes relating to memory/learning?
classical conditioning
Overview of the terminology/ the steps of classical conditioning
- Before training, the unconditioned stimulus (US) e.g. food, produces an unconditioned response (UR) e.g. salivation.
- During training, the conditioned stimulus (CS) e.g. bell, is paired with an unconditioned stimulus e.g. food.
- After training, the CS, e.g. bell, produces a conditioned response (CR) e.g. salivation (without the presence of US)
in eyeblink conditioning in humans, what are the US, CS, CR and UR?
US = airpuff in eye
CS= audio tone
CR and UR = eyeblink/eyelid movement
name of 3rd eyelid that some animals e.g. rabbits, have
nictitating membrane
what is NMR
the nictitating membrane response- involuntary response of nictitating membrane closure to stimulus
why is studying NMR often preferred to eyelid CR?
it has no voluntary interference and low levels of spontaneous activity
draw graphs showing the development of rabbit NMR to an auditory stimulus and airpuff over time
see drawing/description in notes
what are the 2 important features of eyeblink/NMR conditioning
1) US overlaps with the end of CS (delay conditioning
2) US is usually a brief shock or airpuff to skin around eye
briefly outline how the parts of the brain involved in eyeblink conditioning were found historically
- since the 50s the role of the hippocampus in memory has been known, with HM’s lesioned hippocampus leading to anterograde amnesia where STM is intact but LTM isn’t (inability to insert new memories into LTM)
- eyeblink conditioning is LTM, however, eyeblink conditioning is intact in patients with hippocampal lesions (anterograde amnesia). This indicates that there is more than one kind of LTM
- rabbits lacking forebrain/hippocampus/decerebrated rabbits maintain eyeblink conditioning
- hence it was clear the Brainstem and cerebellum had a role
outline early physiological recording/mapping during conditioning
(researchers systematically recorded units in the cerebellar cortex and deep cerebellar nuclei, with the deep cerebellar nuclei showing activation in eyeblink conditioning
(almost all cerebellar output is via these deep nuclei)
outline early lesion work into eyeblink conditioning
- when the entire cerebellum was lesioned, CR was abolished and could not be relearnt
- they found specifically the anterior of interpositus nuclei removed CR. The UR was not affected, indicating the lesion did not cause a motor deficit. To show the lack of CR was not due to deafness, they found unilateral lesions only affect the ipsilateral eyeblink- so the rabbits can hear.
draw and label the unconditional reflex pathway for NMR
a basic 3 neuron reflex arc- see diagram in notes
draw and label the conditioned reflex circuit for NMRadding in conditioned reflex
see notes
input from cerebellar interpositus via red nucleus to the accessory abducens nucleus
where does output for the cerebellum primarily leave from?
the deep cerebellar nuclei
where does input for the cerebellum primarily come in?
the cerebellar cortex
different regions of the cerebellar cortex project to differing parts of
deep cerebellar nuclei
which particular cerebellar cortical region projects to the anterior interpositus and is concerned with eye blink
Hemisphere of lobule VI (HVI)
draw the conditioned reflex pathway, including input from the cerebellar cortex
look in notes
is cerebellar cortex HVI input to interpositus nucleus excitatory or inhibitory?
inhibitory (tonically active)
where does the HVI get its input?
pontine nuclei
draw a diagram of the conditional reflex circuit, including the CS pathway
look at notes
CS from light/sound travelling via forebrain and midbrain to pontine nuclei, via mossy fibres to cerebellar cortex etc.
draw the overall basic circuitry underlying delay NMR conditioning labelling the CR, US, CS and UR aspects of the pathways
see notes