Thomas J. Carew

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The tail-withdrawal reflex of Aplysia can be sensitized by weak stimulation of a site outside the site used to test the reflex or by repeatedly stimulating the test site itself. The sensitization of tail-withdrawal responses is associated with enhanced activation of the tail motor neurons and heterosynaptic facilitation of the monosynaptic connections(More)
Three distinct temporal phases of synaptic facilitation (short-, intermediate-, and long-term) are induced by serotonin (5-HT) at sensory (SN) to motor (MN) synapses in Aplysia. Here, we characterize two mechanistically distinct forms of intermediate-term facilitation (ITF) at tail SN-MN synapses. One form, activity-independent ITF, is produced by five(More)
Mechanical, chemical, or electrical stimulation of the tail elicits a short-latency (less than 1 s) tail-withdrawal reflex that is graded with the intensity of the stimulus. The tail-withdrawal reflex is not elicited by stimulation of parts of the body outside of the tail region. Mechanoafferent neurons innervating the tail are located in a small subcluster(More)
Short- and long-term synaptic facilitation induced by serotonin at Aplysia sensory-motor (SN-MN) synapses has been widely used as a cellular model of short- and long-term memory for sensitization. In recent years, a distinct intermediate phase of synaptic facilitation (ITF) has been described at SN-MN synapses. Here, we identify a novel intermediate phase(More)
Recently there have been exciting advances in understanding the mechanisms and functional roles of a form of short-term synaptic enhancement (STE) that results from an activity-dependent accumulation of Ca2+ in the presynaptic terminal. This form of STE is composed of at least four processes: fast-decaying facilitation (FI), slow-decaying facilitation (F2),(More)
Serotonin (5HT)-induced short-term facilitation and long-term facilitation (STF and LTF) of the monosynaptic connection between tail sensory neurons (SNs) and motor neurons (MNs) in Aplysia have been useful in delineating possible cellular mechanisms contribution to short-term and long-term memory. Previous work from our laboratory showed that LTF can be(More)
Tyrosine kinases have been implicated in cellular processes thought to underlie learning and memory. Here we show that tyrosine kinases play a direct role in long-term synaptic facilitation (LTF) and long-term memory (LTM) for sensitization in Aplysia. Tyrosine kinase activity is required for serotonin-induced LTF of sensorimotor (SN-MN) synapses, and(More)
Three forms of nonassociative learning (habituation, dishabituation, and sensitization) have commonly been explained by a dual-process view in which a single decrementing process produces habituation and a single facilitatory process produces both dishabituation and sensitization. A key prediction of this view is that dishabituation and sensitization should(More)
Recent studies of long-term synaptic plasticity and long-term memory have demonstrated that the same functional endpoint, such as long-term potentiation, can be induced through distinct signaling pathways engaged by different patterns of stimulation. A critical question raised by these studies is whether different induction pathways either converge onto a(More)
Serotonin (5-HT) induces both short-term and long-term facilitation of the identified synaptic connections between sensory and motor neurons of Aplysia. Three independent experimental approaches showed that long-term facilitation can normally be expressed in the absence of short-term facilitation: (i) The 5-HT antagonist cyproheptadine blocked the induction(More)