Biomedical subjects

Gabriel B Mindlin

Publications and source records attributed to Gabriel B Mindlin.

6 recordsLinked to original sources

PubMed2004

Spike timing and synaptic plasticity in the premotor pathway of birdsong.

The neural circuits of birdsong appear to utilize specific time delays in their operation. In particular, the anterior forebrain pathway (AFP) is implicated in an approximately 40- to 50- ms time delay, DeltaT, playing a role in the relative timing of premotor signals from the nucleus HVc to the nucleus robust nucleus of the archistratium (RA) and control/learning signals from the nucleus lateral magnocellular nucleus of the anterior neostratium (lMAN) to RA. Using a biophysical model of synaptic plasticity based on experiments on mammalian hippocampal and neocortical pyramidal neurons, we propose an understanding of this approximately 40- to 50- ms delay. The biophysical model describes the influence of Ca2+ influx into the postsynaptic RA cells through NMDA and AMPA receptors and the induction of LTP and LTD through complex metabolic pathways. The delay, DeltaT, between HVc --> RA premotor signals and lMAN --> RA control/learning signals plays an essential role in determining if synaptic plasticity is induced by signaling from each pathway into RA. If DeltaT is substantially larger than 40 ms, no plasticity is induced. If DeltaT is much less than 40 ms, only potentiation is expected. If DeltaT approximately 40 ms, the sign of synaptic plasticity is sensitive to DeltaT. Our results suggest that changes in DeltaT may influence learning and maintenance of birdsong. We investigate the robustness of this result to noise and to the removal of the Ca2+ contribution from lMAN --> RA NMDA receptors.

Action Potentials↗

PubMed2004

Mapping neural architectures onto acoustic features of birdsong.

The motor pathway responsible for the complex vocalizations of songbirds has been extensively characterized, both in terms of intrinsic and synaptic physiology in vitro and in terms of the spatiotemporal patterns of neural activity in vivo. However, the relationship between the neural architecture of the song motor pathway and the acoustic features of birdsong is not well understood. Using a computational model of the song motor pathway and the songbird vocal organ, we investigate the relationship between song production and the neural connectivity of nucleus HVc (used as a proper name) and the robust nucleus of the archistriatum (RA). Drawing on recent experimental observations, our neural model contains a population of sequentially bursting HVc neurons driving the activity of a population of RA neurons. An important focus of our investigations is the contribution of intrinsic circuitry within RA to the acoustic output of the model. We find that the inclusion of inhibitory interneurons in the model can substantially influence the features of song syllables, and we illustrate the potential for subharmonic behavior in RA in response to forcing by HVc neurons. Our results demonstrate the association of specific acoustic features with specific neural connectivities and support the view that intrinsic circuitry within RA may play a critical role in generating the features of birdsong.

Action Potentials↗

PubMed2003

Highly structured duets in the song of the South American Hornero.

The South American Hornero (Furnarius rufus) is a suboscine bird widely known for its mud-made, oven-looking nest. Beyond their architectural skills, the male and female Horneros sing in highly structured duets. The analysis of field recordings reported in this work reveals that as the male increases the note production rate the female responds by switching to different locking states: the ones predicted by the theory of nonlinear forced oscillators. This gives the duet a most appealing rhythm, and unveils the nonlinear nature of the underlying brain activity needed to generate the song.

Animals↗

PubMed2002

Diversity within a birdsong.

We present a model for the activities of neural circuits in a nucleus found in the brains of songbirds: the robust nucleus of the archistriatum (RA). This is a fore brain song control nucleus responsible for the phasic and precise neural signals driving vocal and respiratory motor neurons during singing. Driving a physical model of the avian vocal organ with the signals generated by the neural model, we produce synthetic songs. This allows us to show that certain connectivity architectures in the RA give rise to a wide range of different vocalizations under simple excitatory instructions.

Journal Article↗

PubMed2002

Coupled optical excitable cells.

In this work we investigate experimentally the dynamics of two coupled optical excitable cells, namely, two semiconductor lasers with optical feedback. We analyze the dynamics observed in terms of the statistical properties of the time series and in terms of the phase space reconstruction from the data. We build a model based on a simple set of deterministic equations (on a two torus) plus noise in order to capture the essential features of the dynamics observed. We discuss the validity of our theoretical results in terms of families of excitable systems and coupling terms.

Journal Article↗

PubMed2002

Neuromuscular control of vocalizations in birdsong: a model.

We present a dynamical model of the processes involved in birdsong production, relating qualitatively its parameters with biological ones. In this way, we intend to unify the activity patterns of the muscles controlling the vocal organ with the resulting vocalization. With relatively simple paths in the parameter space of our model, we reproduce experimental recordings of the Chingolo sparrow (Zonotrichia capensis).

Journal Article↗