Medullary afferent vagal axotomy disrupts NaCl-induced short-term taste aversion learning

Inferior Olive Lesions Impair Concurrent Taste Aversion Learning in Rats

“…Because, as mentioned previously, the cerebellum seems to participate in establishing concurrent TAL (Mediavilla et al, in press) it could be suggested that lesions in the IO nucleus may impair concurrent TAL in a manner similar to the way the vagal pathways are interrupted (Arnedo et al, 1990(Arnedo et al, , 1993. On the other hand, IO lesions may not affect the establishment of sequential TAL since this modality of learning uses different (nonvagal) anatomical pathways Ritter et al, 1980).…”

“…Specifically, vagal lesions at the subdiaphragmatic level and lesions in the medulla oblongata (Arnedo et al, 1990;Arnedo, Gallo, Agü ero, Molina, & Puerto, 1993) and medial parabrachial nucleus (mPBN) (Agü ero, Gallo, Arnedo, Molina, & Puerto, 1996 disrupt concurrent TAL, while lesions in the area pos-trema (AP) (Bernstein, Chavez, Allen, & Taylor, 1992;Coil & Norgren, 1981;Ritter, McGlone, & Kelley, 1980) and lateral parabrachial nucleus (lPBN) (Agü ero, Arnedo, Gallo, & Puerto, 1993a, b) impair sequential TAL. In this regard, a recent study conducted in our laboratory (Mediavilla, Molina, & Puerto, in press) demonstrates the importance of the cerebellum in TAL; lesions limited to the interpositus-dentate region block concurrent TAL, but they do not prevent development of sequential TAL.…”

Electrolytic Lesions of the Pedunculopontine Nucleus Disrupt Concurrent Learned Aversion Induced by NaCl

“…In particular, it could be thought that PPN lesions play a specific role in aversive learning since they impair acquisition of short-term TAL characterized by the simultaneous presentation of the gustatory and visceral stimuli that requires rapid transmission of both sensory modalities. From the data available, we cannot conclude whether the lesions interrupted transmission of the visceral information or if they affected entry of information from the cerebellum, but the results, once again do seem to support the anatomical specificity of the short-term and long-term TAL paradigms (Arnedo et al, , 1993.…”

“…Long-term/sequential learning can be established after administration of hypertonic NaCl in neurologically intact animals (Mediavilla et al, submitted for publication) and animals with lesions in the interpositus dentate region of the cerebellum (Mediavilla et al, 1998) and in animals vagotomized at the level of the medulla oblongata (Arnedo et al, 1993). This is not the case when LiCl is used (independent of the dose) to establish short-term TAL (Arnedo, 1987).…”

“…In this case, the vagus nerve seems to be the main pathway that rapidly conveys information about the aversive visceral stimulus to higher regions. For this reason, vagotomies at the subdiaphragmatic or bulbar level block this type of TAL paradigm (Arnedo et al, , 1991(Arnedo et al, , 1993. It has also been shown that the medial parabrachial nucleus (mPBN) is probably related to establishment of this paradigm (Agüero, Gallo, Arnedo, Molina, & Puerto, 1997), and involvement of the cerebellum has been demonstrated as well (Mediavilla, Molina, & Puerto, 1998).…”