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Characterization of synaptically connected nuclei in a potential sensorimotor feedback pathway in the zebra finch song system.

Williams SM, Nast A, Coleman MJ - PLoS ONE (2012)

Bottom Line: As previously reported, we found similar timing in spontaneous bursts of activity in MMAN and HVC.However, inactivation of MMAN resulted in no consistent change in auditory responses in HVC.Taken together, these results indicate that MMAN provides functional excitatory input to HVC but does not provide significant auditory input to HVC in anesthetized animals.

View Article: PubMed Central - PubMed

Affiliation: Claremont McKenna College, Claremont, California, United States of America.

ABSTRACT
Birdsong is a learned behavior that is controlled by a group of identified nuclei, known collectively as the song system. The cortical nucleus HVC (used as a proper name) is a focal point of many investigations as it is necessary for song production, song learning, and receives selective auditory information. HVC receives input from several sources including the cortical area MMAN (medial magnocellular nucleus of the nidopallium). The MMAN to HVC connection is particularly interesting as it provides potential sensorimotor feedback to HVC. To begin to understand the role of this connection, we investigated the physiological relation between MMAN and HVC activity with simultaneous multiunit extracellular recordings from these two nuclei in urethane anesthetized zebra finches. As previously reported, we found similar timing in spontaneous bursts of activity in MMAN and HVC. Like HVC, MMAN responds to auditory playback of the bird's own song (BOS), but had little response to reversed BOS or conspecific song. Stimulation of MMAN resulted in evoked activity in HVC, indicating functional excitation from MMAN to HVC. However, inactivation of MMAN resulted in no consistent change in auditory responses in HVC. Taken together, these results indicate that MMAN provides functional excitatory input to HVC but does not provide significant auditory input to HVC in anesthetized animals. We hypothesize that MMAN may play a role in motor reinforcement or coordination, or may provide modulatory input to the song system about the internal state of the animal as it receives input from the hypothalamus.

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Stimulation of MMAN functionally excites the ipsilateral HVC.A. Example of the short latency response from MMAN stimulation to HVC response. Top trace is an exemplar of the raw HVC response to MMAN stimulation (large artifact). The dotted grey line denotes the spike threshold set by the user. Middle trace, raster plot of responses to thirty stimulus pulses in MMAN. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of HVC response to MMAN stimulation. B. Longer latency response in HVC to MMAN stimulation. Top two traces, raw exemples of two HVC responses to stimulation of MMAN. Middle trace, raster plot to of HVC response to 30 MMAN stimulations. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of the cumulative response in HVC to MMAN stimulation. For both A and B, bin size = 1 ms. A and B are from two different birds.
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pone-0032178-g005: Stimulation of MMAN functionally excites the ipsilateral HVC.A. Example of the short latency response from MMAN stimulation to HVC response. Top trace is an exemplar of the raw HVC response to MMAN stimulation (large artifact). The dotted grey line denotes the spike threshold set by the user. Middle trace, raster plot of responses to thirty stimulus pulses in MMAN. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of HVC response to MMAN stimulation. B. Longer latency response in HVC to MMAN stimulation. Top two traces, raw exemples of two HVC responses to stimulation of MMAN. Middle trace, raster plot to of HVC response to 30 MMAN stimulations. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of the cumulative response in HVC to MMAN stimulation. For both A and B, bin size = 1 ms. A and B are from two different birds.

Mentions: To examine the functional synaptic input from MMAN to HVC, we stimulated MMAN while recording extracellularly in the ipsilateral HVC (Figure 5). Stimulation in MMAN resulted in a complex excitatory response in HVC (n = 3). In one case there was a clear and consistent excitatory response in HVC with a delay between 10–17 ms (Figure 5A). In two cases, the MMAN stimulation resulted in a very long-lasting response in HVC. The example shown had a response between 9–70 ms (Figure 5B). The initial response (first peak) appeared to be consistent with the time of the response shown in Figure 5A. The second phase of the response could be due to recurrent activation of the feedback loop through HVC. Stimulation outside of MMAN did not result in a consistent latency response in HVC (n = 3; data not shown). These data suggest that MMAN provides functional excitatory input to HVC, with a synaptic delay of 10–17 ms, consistent with a previous report [25].


Characterization of synaptically connected nuclei in a potential sensorimotor feedback pathway in the zebra finch song system.

Williams SM, Nast A, Coleman MJ - PLoS ONE (2012)

Stimulation of MMAN functionally excites the ipsilateral HVC.A. Example of the short latency response from MMAN stimulation to HVC response. Top trace is an exemplar of the raw HVC response to MMAN stimulation (large artifact). The dotted grey line denotes the spike threshold set by the user. Middle trace, raster plot of responses to thirty stimulus pulses in MMAN. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of HVC response to MMAN stimulation. B. Longer latency response in HVC to MMAN stimulation. Top two traces, raw exemples of two HVC responses to stimulation of MMAN. Middle trace, raster plot to of HVC response to 30 MMAN stimulations. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of the cumulative response in HVC to MMAN stimulation. For both A and B, bin size = 1 ms. A and B are from two different birds.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3285214&req=5

pone-0032178-g005: Stimulation of MMAN functionally excites the ipsilateral HVC.A. Example of the short latency response from MMAN stimulation to HVC response. Top trace is an exemplar of the raw HVC response to MMAN stimulation (large artifact). The dotted grey line denotes the spike threshold set by the user. Middle trace, raster plot of responses to thirty stimulus pulses in MMAN. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of HVC response to MMAN stimulation. B. Longer latency response in HVC to MMAN stimulation. Top two traces, raw exemples of two HVC responses to stimulation of MMAN. Middle trace, raster plot to of HVC response to 30 MMAN stimulations. Grey bar indicates time in which stimulus artifacts were removed from the plot. Bottom trace, PSTH of the cumulative response in HVC to MMAN stimulation. For both A and B, bin size = 1 ms. A and B are from two different birds.
Mentions: To examine the functional synaptic input from MMAN to HVC, we stimulated MMAN while recording extracellularly in the ipsilateral HVC (Figure 5). Stimulation in MMAN resulted in a complex excitatory response in HVC (n = 3). In one case there was a clear and consistent excitatory response in HVC with a delay between 10–17 ms (Figure 5A). In two cases, the MMAN stimulation resulted in a very long-lasting response in HVC. The example shown had a response between 9–70 ms (Figure 5B). The initial response (first peak) appeared to be consistent with the time of the response shown in Figure 5A. The second phase of the response could be due to recurrent activation of the feedback loop through HVC. Stimulation outside of MMAN did not result in a consistent latency response in HVC (n = 3; data not shown). These data suggest that MMAN provides functional excitatory input to HVC, with a synaptic delay of 10–17 ms, consistent with a previous report [25].

Bottom Line: As previously reported, we found similar timing in spontaneous bursts of activity in MMAN and HVC.However, inactivation of MMAN resulted in no consistent change in auditory responses in HVC.Taken together, these results indicate that MMAN provides functional excitatory input to HVC but does not provide significant auditory input to HVC in anesthetized animals.

View Article: PubMed Central - PubMed

Affiliation: Claremont McKenna College, Claremont, California, United States of America.

ABSTRACT
Birdsong is a learned behavior that is controlled by a group of identified nuclei, known collectively as the song system. The cortical nucleus HVC (used as a proper name) is a focal point of many investigations as it is necessary for song production, song learning, and receives selective auditory information. HVC receives input from several sources including the cortical area MMAN (medial magnocellular nucleus of the nidopallium). The MMAN to HVC connection is particularly interesting as it provides potential sensorimotor feedback to HVC. To begin to understand the role of this connection, we investigated the physiological relation between MMAN and HVC activity with simultaneous multiunit extracellular recordings from these two nuclei in urethane anesthetized zebra finches. As previously reported, we found similar timing in spontaneous bursts of activity in MMAN and HVC. Like HVC, MMAN responds to auditory playback of the bird's own song (BOS), but had little response to reversed BOS or conspecific song. Stimulation of MMAN resulted in evoked activity in HVC, indicating functional excitation from MMAN to HVC. However, inactivation of MMAN resulted in no consistent change in auditory responses in HVC. Taken together, these results indicate that MMAN provides functional excitatory input to HVC but does not provide significant auditory input to HVC in anesthetized animals. We hypothesize that MMAN may play a role in motor reinforcement or coordination, or may provide modulatory input to the song system about the internal state of the animal as it receives input from the hypothalamus.

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