j *@ - Sociedade Brasileira de Psicologia

Imp tmohbtochemkqtry
149
In addition to conventional neuroanatomical teclmiques, immunohistochemistry
is an important method for analfzing the organization of a nervolzs system.
On the one hand it offers the possibility to recognize anatomically lmidentified
structures or to l-md chemical diversities nmong anatomicaly homogeneous cel
populations. On the other hnnd it rmn provide a first functional asm ct by revealing the
distribution of neurotransmitters or modulatory substances.
In the bee brsin and the SOG, the distribution of the inhibitory nmino acid
GABA (Bicker et al. 1985; Schaefer and Bicker, 1986a), and the presumed neuromodulator
serotonin (Schuermnnn and Klemm, 1984; Rehder et al., 1987) have been
studied in greatest detail. Other transmiters or modulators such as glutamate (Bicker
et aL, 1988), taurine (Schaefer ef al., 1988), and dopamine (Schaefer and Rehder, in
pres) have folowed recently. '
From these exm riments considerations about the fundion of these substances
e-qn be made. GABA is believed to normally serve an inhibitory transm itter fundion.
In the bee brnin , GABA is mninly restricted to local interneurons, where it could affect
synaptic interactions by lateral inhibition (Schaefer and Bicker, 1986a). ln contrast,
serotonin- and dopamin-immunoreactive cels span wide nemopilar areas, kuggesting a
neuromodulatory function (Schuermann and Klemm, 1984; Rehder et al., 1987).
Glutamate as the most abundant free amino acid in the honeybee brain probably acts
as an excitatory transmfter, at least in the motorneurons (Bicker et al. 1988). The
fm ction of taurine, the second-most abundant free nmino add in the bee brain, is
stil subjed to debate. Its function as a transmitter, a membrane stabilizer or as
regulator for Ca++ -flux across the photoreceptor membrane have been discussed
(Gi1$' 1 and Umerwood, 1985 ; Wright et al., 1986; .passantes-Morales and Moran, 1981).
Electrophysiolor
Another approach to the functional properties of a nervous system are .
electrophysiological experiments.
It is assumed that plastic changes during associative processes rmn be observed
on the level of single identified cels. This kind of analysis requires: (1) the identification
of the neurons involved in the proboscis reflex and in the processing of olfactory
information, and their characterization physiologicaly and morphologiœ ly, (2) that
plastic cbnnges of the neurons can be correlated with behavioural changes. Since little
is known even about the normal processing of olfactory information from the antennal
lobes to the mushroom bodies and SOG, intracellular recordings are made from the
sensory projections between antennal lobes and m'tqhroom bodies (a.g.t.'s), from
mltqhroom bodyextrinsic neurons and from interneurons and motom em ons in the