10 Questions
In the conditioned group, the US and CS were delivered in an unpaired manner on day 4 and 5.
False
The amplitude of the response on the third day was significantly larger in the conditioned group than in the control group.
False
The control group received paired stimuli on day 4 and 5.
False
The synaptic response in the control group was significantly larger than in the conditioned group on day 6.
False
The US stimulation alone is sufficient to induce LTP.
False
The EPSP was not affected by the unpaired stimulation in the control group.
True
The LTP induction is mediated by the activation of afferent fibers.
True
The conditioned group showed a decrease in synaptic transmission on day 6.
False
The CS stimulation alone is sufficient to induce synaptic plasticity.
False
The training procedure increased the efficacy of synaptic transmission at the synapses activated by the CS.
True
Study Notes
Hebb's Postulate and Synaptic Plasticity
- Hebb's postulate states that when two neurons are continuously activated, metabolic and morphological changes occur, leading to a modification in how they communicate with each other.
- This concept is often summarized as "cells that fire together wire together."
Experiment on Hippocampus
- The experiment involves placing a recording electrode at the dentate gyrus and a stimulating electrode at the perforant path.
- The stimulating electrode is used to depolarize axonal fibers and induce the release of neurotransmitters (NT) at the synaptic terminals.
- The recording electrode registers a signal coming from a population of excitatory postsynaptic potential (EPSP).
Induction of Long-Term Potentiation (LTP)
- LTP can be induced through electrical stimulation or chemical stimulation.
- Electrical stimulation protocols include Tetanus (100 Hz stimuli for 1 second) and Theta burst stimulation (intervals of 200 ms between every stimulation).
- Chemical stimulation involves adding Glutamate, AMPA, or potassium chloride to the extracellular solution to activate the presynaptic neuron.
LTP and Synaptic Transmission
- After inducing LTP, electrical stimuli at low frequency are used to monitor changes in the postsynaptic response.
- The plot shows the excitatory postsynaptic potential slope, allowing for the observation of possible changes in the post-synaptic potential.
Glutamatergic Receptors
- At the postsynaptic membrane, there are two types of glutamatergic receptors: AMPA receptors and NMDA receptors.
- AMPA receptors are mainly permeable to Na ions and are responsible for the baseline condition of synaptic transmission.
Conditioning and Synaptic Response
- The experiment involves training animals with paired and unpaired stimuli to observe the effect on synaptic response.
- In the conditioned group, the synaptic response is larger in respect to the baseline condition, while in the control group, this effect is not present.
- The larger evoked response is due to the electrical stimulation that activates the mechanisms at the base of LTP induction.
Hebb's postulate explains how neurons communicate with each other, leading to changes in their connections. This concept is summarized as 'cells that fire together wire together'. Learn more about the neural connections and synaptic modifications.
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