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Olfactory responses to natal stream water in sockeye salmon by BOLD fMRI.

Bandoh H, Kida I, Ueda H - PLoS ONE (2011)

Bottom Line: Many studies have shown that juvenile salmon imprint olfactory memory of natal stream odors during downstream migration, and adults recall this stream-specific odor information to discriminate their natal stream during upstream migration for spawning.The odor information processing of the natal stream in the salmon brain, however, has not been clarified.We concluded that sockeye salmon could process the odor information of the natal stream by integrating information in the Dl area of the telencephalon.

View Article: PubMed Central - PubMed

Affiliation: Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan.

ABSTRACT
Many studies have shown that juvenile salmon imprint olfactory memory of natal stream odors during downstream migration, and adults recall this stream-specific odor information to discriminate their natal stream during upstream migration for spawning. The odor information processing of the natal stream in the salmon brain, however, has not been clarified. We applied blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging to investigate the odor information processing of the natal stream in the olfactory bulb and telencephalon of lacustrine sockeye salmon (Oncorhynchus nerka). The strong responses to the natal stream water were mainly observed in the lateral area of dorsal telencephalon (Dl), which are homologous to the medial pallium (hippocampus) in terrestrial vertebrates. Although the concentration of L-serine (1 mM) in the control water was 20,000-times higher than that of total amino acid in the natal stream water (47.5 nM), the BOLD signals resulting from the natal stream water were stronger than those by L-serine in the Dl. We concluded that sockeye salmon could process the odor information of the natal stream by integrating information in the Dl area of the telencephalon.

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Related in: MedlinePlus

Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) maps of the same fish.A: L-serine; B: natal stream water. i: olfactory bulb; ii–iv: telencephalon. The activation map is defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. The BOLD signals are overlaid on the anatomical MRI image. Scale bar = 1.0 mm. CB, cerebellum; Dld, dorsal part of lateral area of dorsal telencephalon; Dlv, ventral part of lateral area of dorsal telencephalon; GL, glomerular layer; HL, hypothalamus; OB, olfactory bulb; OT, optic tectum; T, telencephalon.
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pone-0016051-g001: Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) maps of the same fish.A: L-serine; B: natal stream water. i: olfactory bulb; ii–iv: telencephalon. The activation map is defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. The BOLD signals are overlaid on the anatomical MRI image. Scale bar = 1.0 mm. CB, cerebellum; Dld, dorsal part of lateral area of dorsal telencephalon; Dlv, ventral part of lateral area of dorsal telencephalon; GL, glomerular layer; HL, hypothalamus; OB, olfactory bulb; OT, optic tectum; T, telencephalon.

Mentions: Figure 1 shows the averaged functional images from six trials of the same fish defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. There were very few variations of activated areas among six fish. The activated pixels were elicited by a 3-min odorant stimulation of L-serine (Fig. 1A) or natal stream water (Fig. 1B) in the right olfactory epithelium. Except for one BOLD signal observed in the left hemisphere of the olfactory bulb, the BOLD signals were mostly detected in the right olfactory bulb and telencephalon (Fig. 1A, B). There were not many differences in activated areas between L-serine and the natal stream water in the olfactory bulb (Fig. 1Ai and 1Bi). In contrast, the activated extent in the telencephalon were clearly different between L-serine (Fig. 1Aii–iv) and the natal stream water (Fig. 1Bii–iv). Indeed, the BOLD signal response to the natal stream water was significantly higher than the response to L-serine (P<0.05). The distinct activations were mainly observed in dorsal (Dld) and ventral part (Dlv) of the lateral area of dorsal telencephalon (Fig. 1Bii–iv).


Olfactory responses to natal stream water in sockeye salmon by BOLD fMRI.

Bandoh H, Kida I, Ueda H - PLoS ONE (2011)

Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) maps of the same fish.A: L-serine; B: natal stream water. i: olfactory bulb; ii–iv: telencephalon. The activation map is defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. The BOLD signals are overlaid on the anatomical MRI image. Scale bar = 1.0 mm. CB, cerebellum; Dld, dorsal part of lateral area of dorsal telencephalon; Dlv, ventral part of lateral area of dorsal telencephalon; GL, glomerular layer; HL, hypothalamus; OB, olfactory bulb; OT, optic tectum; T, telencephalon.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3022028&req=5

pone-0016051-g001: Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) maps of the same fish.A: L-serine; B: natal stream water. i: olfactory bulb; ii–iv: telencephalon. The activation map is defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. The BOLD signals are overlaid on the anatomical MRI image. Scale bar = 1.0 mm. CB, cerebellum; Dld, dorsal part of lateral area of dorsal telencephalon; Dlv, ventral part of lateral area of dorsal telencephalon; GL, glomerular layer; HL, hypothalamus; OB, olfactory bulb; OT, optic tectum; T, telencephalon.
Mentions: Figure 1 shows the averaged functional images from six trials of the same fish defined by a threshold of P<0.05 corrected for multiple comparisons using false discovery rate approach. There were very few variations of activated areas among six fish. The activated pixels were elicited by a 3-min odorant stimulation of L-serine (Fig. 1A) or natal stream water (Fig. 1B) in the right olfactory epithelium. Except for one BOLD signal observed in the left hemisphere of the olfactory bulb, the BOLD signals were mostly detected in the right olfactory bulb and telencephalon (Fig. 1A, B). There were not many differences in activated areas between L-serine and the natal stream water in the olfactory bulb (Fig. 1Ai and 1Bi). In contrast, the activated extent in the telencephalon were clearly different between L-serine (Fig. 1Aii–iv) and the natal stream water (Fig. 1Bii–iv). Indeed, the BOLD signal response to the natal stream water was significantly higher than the response to L-serine (P<0.05). The distinct activations were mainly observed in dorsal (Dld) and ventral part (Dlv) of the lateral area of dorsal telencephalon (Fig. 1Bii–iv).

Bottom Line: Many studies have shown that juvenile salmon imprint olfactory memory of natal stream odors during downstream migration, and adults recall this stream-specific odor information to discriminate their natal stream during upstream migration for spawning.The odor information processing of the natal stream in the salmon brain, however, has not been clarified.We concluded that sockeye salmon could process the odor information of the natal stream by integrating information in the Dl area of the telencephalon.

View Article: PubMed Central - PubMed

Affiliation: Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, Sapporo, Japan.

ABSTRACT
Many studies have shown that juvenile salmon imprint olfactory memory of natal stream odors during downstream migration, and adults recall this stream-specific odor information to discriminate their natal stream during upstream migration for spawning. The odor information processing of the natal stream in the salmon brain, however, has not been clarified. We applied blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging to investigate the odor information processing of the natal stream in the olfactory bulb and telencephalon of lacustrine sockeye salmon (Oncorhynchus nerka). The strong responses to the natal stream water were mainly observed in the lateral area of dorsal telencephalon (Dl), which are homologous to the medial pallium (hippocampus) in terrestrial vertebrates. Although the concentration of L-serine (1 mM) in the control water was 20,000-times higher than that of total amino acid in the natal stream water (47.5 nM), the BOLD signals resulting from the natal stream water were stronger than those by L-serine in the Dl. We concluded that sockeye salmon could process the odor information of the natal stream by integrating information in the Dl area of the telencephalon.

Show MeSH
Related in: MedlinePlus