Questions and Answers
What type of stimulus does an air puff to the cornea represent?
What is the key site of plasticity in the eye blink conditioning model?
Purkinje cells
What is required for learning in the eye blink conditioning circuit?
Conditioned stimulus paired with unconditioned stimulus
Which of the following statements about Purkinje cells is true?
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The conditioned stimulus in eye blink conditioning is the _____.
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The unconditioned stimulus in eye blink conditioning is the _____.
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What happens to Purkinje cells after conditioning?
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Purkinje cells release GABA onto the neurons of the nucleus interpositus.
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What is the role of mossy fibers in the conditioned stimulus pathway?
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What results from the convergence of CS and US in eye blink conditioning?
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What is the timeframe within which the conditioned stimulus and unconditioned stimulus must meet to facilitate learning?
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Study Notes
Air Puff Conditioning
- Air puff to the cornea serves as an unconditioned stimulus, triggering an eye blink response in humans and nictitating membrane response in rabbits.
- Sensory information from the cornea follows the trigeminal nerve to the cranial motor nucleus, leading to eyelid closure.
- Reflex pathways remain constant, allowing for the conditioned stimulus to evoke an eyeblink response.
Purkinje Cells Function
- Purkinje cells are crucial for neural plasticity involved in conditioning processes.
Cerebellum Access Mechanisms
- Conditioned stimulus access to the cerebellum occurs via mossy fibers interacting with granule cells, activating parallel fiber systems, allowing communication with Purkinje cells.
- The reflex pathway remains accessible for the unconditioned stimulus but activates only after conditioning.
Reflex Pathway Activation
- After learning, the conditioned stimulus gains access to the reflex response pathway.
Inhibition Before Conditioning
- Prior to conditioning, the conditioned stimulus (tone) can only partially activate interpositus neurons due to strong GABAergic inhibition from Purkinje cells.
- The unconditioned stimulus (air puff) generates the eye blink response by bypassing this inhibition.
Timing of Stimulus Pairing
- Learning necessitates that the conditioned stimulus must be paired with the unconditioned stimulus within a critical time frame of approximately 200 milliseconds, targeting Purkinje cell dendrites.
Anatomical Pathways
- The conditioned stimulus pathway involves the Pontine nucleus, mossy fibers, granule cells, and Purkinje cells.
- The unconditioned stimulus pathway includes the inferior olive and climbing fibers leading to the eye blink response.
- Purkinje cells release GABA and inhibit Nucleus Interpositus (Int) activity while being postsynaptic to climbing fibers.
Conditioning Process
- The conditioned stimulus is represented by a tone.
- The unconditioned stimulus is identified as the air puff.
Purkinje Cells Overview
- Purkinje cells serve as the exclusive inhibitory output neurons of the cerebellum, projecting to cerebellar nuclei and influencing motor systems.
Long-Term Depression Mechanism
- Convergence of conditioned (mossy fibers) and unconditioned (climbing fibers) stimuli leads to long-term depression (LTD) of synapses:
- Upon activation, glutamate released at Purkinje dendrites causes calcium release from internal stores.
- Calcium inactivation of glutamate receptors occurs slowly, making them temporarily susceptible.
- If the unconditioned stimulus is applied timely, it can lead to internalization of glutamate receptors, resulting in LTD. Delayed application results in loss of susceptibility, preventing LTD.
Eye Blink Conditioning Circuit Dynamics
- The circuit begins with the tone engaging auditory pathways, leading to granule and Purkinje cell activation, but inhibition prevents conditioned responses until learning occurs.
- Ultimately, successful timing of tone followed by air puff leads to conditioned eyeblink responses.
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Description
This quiz covers key concepts related to classical conditioning using the air puff eye model. You will learn about unconditioned stimuli, reflex responses, and the physiological mechanisms involved in eye blinks. Perfect for students studying psychology and behavioral responses.
