LONG-TERM SYNAPTIC PLASTICITY IN THE HONEYBEE

A monosynaptic response was recorded in vivo in the mushroom body of t he bee brain, an important site for memory consolidation. Focal electr ical stimulation of a major afferent input evoked an extracellular fie ld potential that consisted of a presynaptic fiber volley and a postsy naptic response. We report a long-lasting potentiation of the synaptic response (2.6-fold increase; less than or equal to 3.5 h). Potentiati on of the response was induced by low-frequency stimulation (0.02-1.0 Hz), was input specific. and was maintained in the absence of stimulat ion. Paired-pulse facilitation of the response was converted to paired -pulse depression after potentiation, suggesting a presynaptic mechani sm. This is the first demonstration of long-term synaptic plasticity i n the insect brain.