Biomedical subjects

Anne-Marie M Oswald

Publications and source records attributed to Anne-Marie M Oswald.

3 recordsLinked to original sources

PubMed2006

Synaptic mechanisms underlying auditory processing.

In vivo voltage clamp recordings have provided new insights into the synaptic mechanisms that underlie processing in the primary auditory cortex. Of particular importance are the discoveries that excitatory and inhibitory inputs have similar frequency and intensity tuning, that excitation is followed by inhibition with a short delay, and that the duration of inhibition is briefer than expected. These findings challenge existing models of auditory processing in which broadly tuned lateral inhibition is used to limit excitatory receptive fields and suggest new mechanisms by which inhibition and short term plasticity shape neural responses.

Animals↗

PubMed2004

Parallel processing of sensory input by bursts and isolated spikes.

Burst firing is commonly observed in many sensory systems and is proposed to transmit information reliably. Although a number of biophysical burst mechanisms have been identified, the relationship between burst dynamics and information transfer is uncertain. Electrosensory pyramidal cells have a well defined backpropagation-dependent burst mechanism. We used in vivo, in vitro, and modeling approaches to investigate pyramidal cell responses to mimics of behaviorally relevant sensory input. We found that within a given spike train, bursts are biased toward low-frequency events while isolated spikes simultaneously code for the entire frequency range. We also demonstrated that burst dynamics are essential for optimal feature detection but are not required for stimulus estimation. We conclude that burst and spike dynamics can segregate a single spike train into two parallel and complementary streams of information transfer.

Action Potentials↗

PubMed2002

Dynamically interacting processes underlie synaptic plasticity in a feedback pathway.

Descending feedback is a common feature of sensory systems. Characterizing synaptic plasticity in feedback inputs is essential for delineating the role of feedback in sensory processing. In this study, we demonstrate that multiple interacting processes underlie the dynamics of synaptic potentiation in one such sensory feedback pathway. We use field recording and modeling to investigate the interaction between the transient high-magnitude potentiation (200-300%) elicited during tetanic stimulation of the feedback pathway and the lower magnitude posttetanic potentiation (PTP; ~30%) that slowly decays on cessation of the tetanus. The amplitude of the observed transient potentiation is graded with stimulus frequency. In contrast, the induction of PTP has a stimulus frequency threshold between 1 and 5 Hz, and its amplitude is independent of stimulus frequency. We suggest that the threshold for PTP induction may be linked to a minimum level of sustained potentiation (MSP) during repetitive trains of stimuli. We have developed a novel model that describes the interaction between the transient plasticity observed during train stimulation and the generation of PTP. The model combines a multiplicative, facilitation-depression-type (FD) model that describes the transient plasticity, with an enzymatic network that describes the dynamics of PTP. The model links transient plasticity to PTP through an input term that reflects MSP. The stratum fibrosum-pyramidal cell (StF-PC) synapse investigated in this study is the terminus of a feedback pathway to the electrosensory lateral line lobe (ELL) of a weakly electric gymnotiform fish. Dynamic plasticity at the StF-PC synapse may contribute to the putative role of this feedback pathway as a sensory searchlight.

Action Potentials↗