Modulation of long-term synaptic plasticity at excitatory striatal synapses

Area of Science:

• Neuroscience
• Synaptic Plasticity
• Neurotransmission

Background:

• Long-term plasticity in the striatum is crucial for motor control and learning.
• The roles of metabotropic glutamate receptors (mGluRs) and dopamine in modulating this plasticity are not fully understood.

Purpose of the Study:

• To investigate how intrinsic metabotropic glutamate receptor activation and nigrostriatal dopamine influence long-term plasticity at excitatory striatal synapses.
• To determine the specific contributions of mGluRs and dopamine to activity-dependent plasticity.

Main Methods:

• Intracellular recordings were used to measure excitatory postsynaptic potentials (EPSPs) in striatal synapses.
• Tetanic stimulation was applied to induce long-term plasticity.
• Pharmacological blockade of mGluRs (using 3-aminophosphonovaleric acid) and lesions of the substantia nigra (using 6-hydroxydopamine) were employed.

Main Results:

• Tetanic stimulation typically induced a slight long-term depression of EPSPs, but response patterns were variable.
• Blocking mGluRs increased the proportion of cells exhibiting long-term potentiation.
• Lesions to the substantia nigra also increased the expression of long-term potentiation.
• Paired-pulse stimulation suggested a presynaptic component to long-term plasticity expression.

Conclusions:

• Metabotropic glutamate receptor and dopamine receptor activation regulate the expression of activity-dependent plasticity at corticostriatal synapses.
• These modulatory systems fine-tune synaptic plasticity, influencing whether potentiation or depression occurs.