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Fig. 4. Effects of removal of external Ca2+ and Na+ on
olfaction in Carassius auratus. (A) Typical electroencephalogram
(EEG) responses from the olfactory bulb (lower traces) and their integrated
activity (upper traces) to 10-5 mol l-1 L-serine (black
horizontal bars) in AFW (open horizontal bar), to Ca2+-free and to
Na+-free (shaded horizontal bars) AFW flowing over the olfactory
epithelium. All three responses were recorded from the same fish. (B,C)
Histograms showing pooled data (means + S.E.M.) of responses to
10-5 mol l-1 L-serine in Ca2+-free AFW (B)
and Na+-free AFW (C) compared with their respective controls
(10-5 mol l-1 L-serine in AFW). The number of
observations is shown in parentheses. *P<0.05
(Student's t-test for paired data).