Functional restoration of acoustic units and adult-generated neurons after hypothalamic lesion.
The hypothalamus of the adult ring dove contains acoustic units that respond to species-specific coo vocalization. Loss of nest coo leads to unsuccessful breeding. However, the recovery of nest coo in some doves suggests that these units are capable of self-renewal. We have previously shown that lesioning the hypothalamus generates the addition of new neurons at the lesioned area. In this study, we sought to determine whether lesion-induced new neurons are involved in the recovery of coo-responsive units. We systematically recorded electrical activity in the ventromedial nucleus (VMN) of the hypothalamus, before and after lesion, for varying periods up to 3 months. Recordings were made when the birds were at rest (spontaneous discharge) and when the birds were exposed to acoustic stimulations (evoked discharge). Concurrently, the lesioned area was monitored for changes in cell types by using bromodeoxyuridine (BrdU) to label newly divided cells and NeuN to identify mature neurons. For 1 month after lesion, there was no sign of electrical activity, and only BrdU-labeled cells were present. When the first electrical activity occurred, it displayed abnormal spontaneous bursting patterns. The mature discharge patterns (both spontaneous and evoked) occurred after detection of BrdU+/NeuN+ double-labeled cells 2-3 months postlesion and were similar to those found in intact and sham-lesioned birds. Double-labeled cells bore morphologic characteristics of a neuron and were confirmed with z-stack analysis using confocal laser scanning microscopy. Moreover, double-labeled cells were not stained for glial fibrillary acidic protein (GFAP), suggesting that they were neurons. The number of coo-responsive units was significantly correlated with that of BrdU+/NeuN+ cells. Furthermore, the marker for recording sites revealed that coo-responsive units were colocalized with BrdU+/NeuN+ cells. Taken together, the evidence strongly suggests that lesion-induced addition of new neurons promotes the functional recovery of the adult hypothalamus.
Cheng
Mei-Fang
MF
Department of Psychology, Rutgers University, Newark, New Jersey 07102, USA. mcheng@axon.rutgers.edu
Peng
Jing-Pian
JP
Chen
Gang
G
Gardner
Jeffrey P
JP
Bonder
Edward M
EM
D000161:Acoustic Stimulation / Q000379:methods; D000162:Acoustics; D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000704:Analysis of Variance; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D002452:Cell Count / Q000379:methods; D048429:Cell Size / Q000502:physiology / Q000528:radiation effects; D002470:Cell Survival / Q000502:physiology; D010856:Columbidae; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D009474:Neurons / Q000502:physiology* / Q000528:radiation effects; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D020127:Recovery of Function / Q000502:physiology*; D013997:Time Factors; D014697:Ventromedial Hypothalamic Nucleus / Q000166:cytology / Q000293:injuries / Q000502:physiology; D014828:Vocalization, Animal / Q000502:physiology*
D005904:Glial Fibrillary Acidic Protein; D010751:Phosphopyruvate Hydratase; D001973:Bromodeoxyuridine