“There's always a pigeonThat'll come shit on your hood”: Hippocampal Formation in Homing Pigeon Sun Compass-Based Spatial Learning
Historical Aspect-Military • Ancient times • Persian King Cyrus sent information • Greeks sent news of Olympics victories • France used status and prestige • War times • 1870 Franco Prussian war 4 month siege of Paris had 400 birds deliver over 115,000 messages • WWI Gen. John Pershing ordered development of pigeon communication system
Historical Aspect-Military • World War I and II • WWI • Over half million birds used • 95% success rate (more accurate than wire service) • Cher Ami most famous • WWII • Germans had 50,000 pigeons ready • Americans rebuilt pigeon program • Used during radio silence times and as recon • English and Germans develop falcon program to intercept birds and communication • Pigeon Clip. World of Wings Center
BACKGROUND • Mammalian and Bird HF homologous • Development • Connectivity • Neurochemistry • For birds, lesioning the hippocampus impairs landmark navigation • In particular, homing pigeons HF critical for navigation map learning, navigation by landmarks near and far.
Background • Pigeons in unfamiliar locations utilize navigational maps to determine location relative to their home • Enclosed areaHFL impair acquisition, HFR do not • Homing pigeons dependent on sun compass/magnetic field for sense of direction
materials • N=60 homing pigeons (all have previous homing experience • 3 groups=C, HFR, HFL • Ablations to left and right hippocampal regions were done through aspiration under anesthesia. • Sham were anaesthetized, incised, and sutured. • Training during sun visibility
PRE-TRAINING • 1st day: Food visible in the goal boxes • 2nd day: Food not visible in the goal boxes • Pigeon removed after all food eaten or after 30 min • 3rd day: Food only in target goal box • Pigeon only removed if food found correction procedure
EXPERIMENTAL TRAINING • Ten trials per session • Each trial: pigeon allowed to enter 1 box and then removed • No correction procedure • Trial scored correct if pigeon chose same target box as before • Birds tested alternately if at same time (ITI around 15-20 min) • Test probe=5 trials w/ no food reward
Experiment 1…cont’d • Pigeons housed for 6 days in light proof room • Artificial day started and ended 6 hrs before natural light phase • First 3 days: Pigeons fed normally • Last 3 days: Pigeons not given any food • Tested in arena w/o feature cues 5 times (unreinforced)
Experiment 2…cont’d • Pigeons housed for 6 days in light proof room • Artificial day started and ended 6 hrs before natural light phase • Tested in arena 5 times (unreinforced) with the sun compass and feature cues in CONFLICT with each other
Experiment 3—cont’d • After training ended, pigeons given 1 test session • Associated feature cues rotated 90º • Test session had 5 trials (unreinforced) with the sun compass and feature cues in CONFLICT with each other. • **Did they do the 6hr light phase?
Experiment 4—cont’d • Pigeons housed for 6 days in light proof room • Artificial day started and ended 6 hrs before natural light phase • Tested in arena w/o feature cues • To demonstrate sun compass learning w/o feature cues • Tested in arena w/ 5 trials (unreinforced)
Histology and lesions • Exp 1 and 2 pigeons sacrificed • Black area = damage common to 9/12 pigeons • Striped area = damage common to 4/12 pigeons
Discussion • Controls • Preferred sun compass based goals, esp seen during the 6hr phase shift • Preferred sun compass over feature cues in spatial learning and behavior
DISCUSSION • HFL Pigeons • No indication that shifts in orientation was due to sun compass use • EXP 3 pigeons shifted mainly due to feature cues • Could also be relying on other information to guide their directions (EXP 1 birds learned tasks without feature cues) • Therefore, HFL pigeons had a sun compass learning deficit
DISCUSSION • HFR Pigeons • In general, shifted direction appropriately according towards the sun compass • However, during presence of feature cues, HFR pigeons preferred use of feature cues vs. sun compass (ability for sun compass is still present • Therefore, ONLY the left HF is capable of supporting sun compass-based learning and plays the more important role in sun compass based spatial learning
CONCLUSIONS • Partial segregation of the spatial processing elements involved in sun compass based learning (via HL) and goal location w/in geometrical framework (via HR) • Lesioned HR had sun compass abilities but preferred feature cues when available • Relying on extra-hippcampal circuits when there are feature cues? Not relying on these circuits when there aren’t feature cues? • Lesioned HL impaired spatial cognition and prevented sun-compass based learning • Are there extra-hippocampal circuits? Or is it just the right region?
REFERENCES • Gagliardo, A., Ioale, P., Odetti, F., Bingman, V.P., Seigel, J.J., & Vallortigara, G. (2001). Hippocampus and homing in pigeons: left and right hemispheric differences in navigational map learning. European Journal of Neuroscience, 13, 1617-1624. • Glagliardo, A., Vallortigara, G., Nardi, D., & Bingman, V.P. (2005). A lateralized avian hippocampus: preferential role of the left hippocampal formation in homing pigeon sun compass-based spatial learning. European Journal of Neuroscience, 22, 2549-2559. • World of Wings http://www.pigeoncenter.org/militarypigeons.html