Age at Deafening Affects the Stability of Learned Song in Adult Male Zebra Finches

Abstract

Male zebra finches (Taeniopygia guttata) master the imitation of a song model 80-90 d after hatching and retain it with little change for the rest of their lives. Acquisition and maintenance of this imitation require intact hearing. A previous report showed that male zebra finches deafened as adults start to lose some of the acoustic and temporal features of their song a few weeks after deafening and that by 16 weeks the learned song is severely degraded (Nordeen and Nordeen, 1992). However, this previous study noted no correlation between the age at deafening and the subsequent timing and extent of song loss. We deafened adult male zebra finches ranging in age from 81 d to 6 years. The song of birds deafened at the younger ages (81-175 d) deteriorated severely after a few weeks, and within that age bracket, the older the bird was at deafening, the longer it took for this degradation to occur and the slower the subsequent process of song deterioration. The song of birds deafened at 2 years and older showed little change during the first 51 weeks after deafening but was grossly altered by 100 weeks. We suggest (1) that this age effect could be independent of experience or (2) that each time a bird sings, a little bit of learning-motor engrainment-occurs, adding to memory duration in a cumulative manner.

Deafening-Induced Vocal Deterioration in Adult Songbirds Is Reversed by Disrupting a Basal Ganglia-Forebrain Circuit

“…The size of these structures (especially HVC) differs tremendously among individual adult zebra finches (Ward et al, 1998;Airey et al, 2000). Also, the diminishing effects of deafening with age (Lombardino and Nottebohm, 2000) could reflect a decline in the overall level of variability in LMAN activity (Kao and Brainard, 2006), and/or a greater influence of HVC-RA connections over behavior. Perhaps HVC-RA synapses become more stable over time, or the age-related decrease in the addition of new HVC neurons (Wang et al, 2002) reduces the susceptibility of the HVC-RA pathway to LMAN activity.…”

Long-Term Potentiation in an Avian Basal Ganglia Nucleus Essential for Vocal Learning

“…Pairing-induced potentiation in male adult zebra finches provides a possible mechanism underlying active song maintenance in adult songbirds and could also contribute to song degradation known to occur after manipulation of the auditory feedback (Woolley and Rubel, 1997;Leonardo and Konishi, 1999;Lombardino and Nottebohm, 2000;Brainard and Doupe, 2001) or tracheosyringeal nerve injury (Williams and Mehta, 1999). We next tested whether this form of LTP is also present in young zebra finches undergoing song learning.…”

“…LTP is inducible in adult and juvenile birds, suggesting that it may contribute to song degradation in adult birds, induced by manipulations of auditory feedback or sectioning of tracheosyringeal nerves (Woolley and Rubel, 1997;Leonardo and Konishi, 1999;Williams and Mehta, 1999;Lombardino and Nottebohm, 2000;Brainard and Doupe, 2001), and to sensorimotor learning in juvenile birds. Although our inability to induce LTP in younger birds does not necessarily exclude its presence, the difficulty suggests that this form of plasticity may not play a primary role during sensory learning.…”

“…In the sensorimotor learning phase (35-90 d after hatching), the young bird practices refining his own vocalizations to match the memorized template, after which he produces a highly stereotyped song resembling the tutor song. After the learning phases, the bird actively maintains song quality using auditory feedback (Nordeen and Nordeen, 1992;Woolley and Rubel, 1997;Leonardo and Konishi, 1999;Brainard and Doupe, 2000b;Lombardino and Nottebohm, 2000). The brain regions underlying vocal learning and production are known as the song system ( Fig.…”

Plasticity in Primary Auditory Cortex of Monkeys with Altered Vocal Production

“…Alterations in perceived formants induce compensatory changes in vowel production (Houde, 1997;Houde and Jordan, 1997, 2002. Similarly, deafness in birds during song learning interferes strongly with the production of a viable and stable song (Nordeen and Nordeen, 1992;Brainard and Doupe, 2000a,b;Lombardino and Nottebohm, 2000). These behavioral studies indicate that auditory feedback is integral to speech/vocal production and is directly involved in the dynamic control of some aspects of voicing.…”