Sociality and septal neuropeptides what is being modulated

Manipulations of septal AVT produce results that are consistent with the results described above, and support the idea that the AVT projection from the BSTm to the LS promotes affiliative behaviour. For instance, intraseptal AVT infusions reduce resident-intruder aggression in two species of songbirds that independently evolved territoriality — the violet-eared waxbill (Goodson, 1998b) and the field sparrow (Spizella pusilla; Fig. 4A) (Goodson, 1998a). In the colonial zebra finch, AVT actually increases aggression during competition to court (Goodson and Adkins-Regan, 1999; Goodson et al., 2004); however, this aggression is specifically linked to appetitive sexual behaviour (i.e. an affiliative context) (Adkins-Regan and Robinson, 1993).

These context-dependent effects on aggression are consistent with the hypothesis that AVT is influencing a broader emotional state such as anxiety. For instance, heightened anxiety may reduce aggression in a territorial bird that is faced with an intruder, but increase aggression in a gregarious zebra finch that is competing for a mate. Similar context-dependent effects are observed in male field sparrows housed outdoors on semi-natural territories. As just mentioned, resident-intruder aggression in field sparrows is decreased by intraseptal AVT infusions. However, spontaneous use of an agonistic song type during the ''dawn chorus'' (a time of elevated singing) is increased (Fig. 4B, C) (Goodson, 1998a). Both the decrease in overt aggression (when faced with an actual intruder) and the increase in agonistic singing (when an animal is attempting to keep

  1. 3. Species differences in linear 125I-V1a antagonist binding (adapted with permission from Goodson et al., 2006). (A, B) Representative binding in the septum of the territorial violet-eared waxbill (VEW; A), and moderately gregarious Angolan blue waxbill (ABW; B). (C, D) Representative sections for a male Angolan blue waxbill and male spice finch (colonial), respectively, showing species differences in binding for the nidopallium (N) and other areas of the forebrain. (E) Linear 125I-V1a antagonist binding in the dorsal (pallial) portion of the lateral septum (LS), shown as decompositions per minute per milligram (dpm/mg; means+ SEM). Different letters above the error bars denote significant species differences (Fisher's PLSD following significant ANOVA; p<0.05). The scale bar in B corresponds to 500 mm in panels A-B; the scale bar in D corresponds to 1 mm in panels C-D. Abbreviations: E, entopallium; HA, apical part of the hyperpallium; LSc, caudal division of the lateral septum (dorsal, ventrolateral and ventral zones denoted as LSc.d, LSc.vl and LSc.v, respectively); LSr, rostral division of the lateral septum; LSt, lateral striatum; MS, medial septum; N, nidopallium; SH, septohippocampal septum; TeO, optic tectum.
  2. 3. Species differences in linear 125I-V1a antagonist binding (adapted with permission from Goodson et al., 2006). (A, B) Representative binding in the septum of the territorial violet-eared waxbill (VEW; A), and moderately gregarious Angolan blue waxbill (ABW; B). (C, D) Representative sections for a male Angolan blue waxbill and male spice finch (colonial), respectively, showing species differences in binding for the nidopallium (N) and other areas of the forebrain. (E) Linear 125I-V1a antagonist binding in the dorsal (pallial) portion of the lateral septum (LS), shown as decompositions per minute per milligram (dpm/mg; means+ SEM). Different letters above the error bars denote significant species differences (Fisher's PLSD following significant ANOVA; p<0.05). The scale bar in B corresponds to 500 mm in panels A-B; the scale bar in D corresponds to 1 mm in panels C-D. Abbreviations: E, entopallium; HA, apical part of the hyperpallium; LSc, caudal division of the lateral septum (dorsal, ventrolateral and ventral zones denoted as LSc.d, LSc.vl and LSc.v, respectively); LSr, rostral division of the lateral septum; LSt, lateral striatum; MS, medial septum; N, nidopallium; SH, septohippocampal septum; TeO, optic tectum.

Fig. 4. Effects of intraseptal AVT infusions in male field sparrows housed on semi-natural territories (field-based flight cages placed in natural habitat; adapted with permission from Goodson, 1998a). (A) Chases during a 15-min resident-intruder test following infusion of saline control or 100 ng AVT. (B) The number of simple and complex songs given spontaneously during the dawn singing period; these song types are multipurpose and strictly agonistic, respectively (Nelson and Croner, 1991). (C) The ratio of complex to simple songs, showing an increase in the agonistic content of song following intraseptal infusion of AVT. All data are shown as means + SEM; *p<0.05, Wilcoxon signed ranks; n = 7.

Simple Complex

Fig. 4. Effects of intraseptal AVT infusions in male field sparrows housed on semi-natural territories (field-based flight cages placed in natural habitat; adapted with permission from Goodson, 1998a). (A) Chases during a 15-min resident-intruder test following infusion of saline control or 100 ng AVT. (B) The number of simple and complex songs given spontaneously during the dawn singing period; these song types are multipurpose and strictly agonistic, respectively (Nelson and Croner, 1991). (C) The ratio of complex to simple songs, showing an increase in the agonistic content of song following intraseptal infusion of AVT. All data are shown as means + SEM; *p<0.05, Wilcoxon signed ranks; n = 7.

other animals away) could potentially result from an increase in anxiety.

In support of this idea, septal V1a receptors influence anxiety in rodents (Landgraf et al., 1995) and V1a-like receptors modulate neural responses of the LS to stress in song sparrows (Melospiza melodia) (Goodson and Evans, 2004). In general, manipulations of AVT/AVP that influence social behaviour also tend to influence anxiety (Pitkow et al., 2001; Bielsky et al., 2004).

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