Biomedical subjects

Gary J Rose

Publications and source records attributed to Gary J Rose.

7 recordsLinked to original sources

PubMed2005

Pulse rise time but not duty cycle affects the temporal selectivity of neurons in the anuran midbrain that prefer slow AM rates.

Recovery-type auditory neurons in the anuran inferior colliculus (IC) respond with band-pass or low-pass selectivity for sinusoidal AM. These cells respond to each modulation cycle at slow AM rates and respond only at the onset of fast AM or pulse repetition rate (PRR) stimuli, failing to recover from the effects of early pulses. This selectivity is not altered by changes in pulse duty cycle. The recovery process is governed therefore by the interpulse interval and not the dimension of the gap between sound pulses. Most of these neurons preferred fast rise times, which is characteristic of the sound pulses in the calls of Hyla regilla and Rana pipiens, the two species selected for this study.

Acoustic Stimulation↗

PubMed2004

Species-typical songs in white-crowned sparrows tutored with only phrase pairs.

Modern theories of learned vocal behaviours, such as human speech and singing in songbirds, posit that acoustic communication signals are reproduced from memory, using auditory feedback. The nature of these memories, however, is unclear. Here we propose and test a model for how complex song structure can emerge from sparse sequence information acquired during tutoring. In this conceptual model, a population of combination-sensitive (phrase-pair) detectors is shaped by early exposure to song and serves as the minimal representation of the template necessary for generating complete song. As predicted by the model, birds that were tutored with only pairs of normally adjacent song phrases were able to assemble full songs in which phrases were placed in the correct order; birds that were tutored with reverse-ordered phrase pairs sang songs with reversed phrase order. Birds that were tutored with all song phrases, but presented singly, failed to produce normal, full songs. These findings provide the first evidence for a minimal requirement of sequence information in the acoustic model that can give rise to correct song structure.

Acoustic Stimulation↗

PubMed2004

Structure and function of neurons in the complex of the nucleus electrosensorius of Sternopygus and Eigenmannia: diencephalic substrates for the evolution of the jamming avoidance response.

The ability to discriminate the sign of the difference in frequency (DF) between two wavelike signals is integral to the jamming avoidance response (JAR) of weakly electric gymnotiform fish such as Eigenmannia. 'Whole-cell' intracellular recordings from neurons in the nucleus electrosensorius (nE) of Sternopygus, a gymnotiform that lacks the JAR, revealed that this nucleus receives information from both the ampullary and the tuberous electrosensory systems. Most tuberous units responded to DF stimuli, and many of these cells were DF sign-sensitive, i.e., they responded differently for one sign of DF. Although the distribution of ampullary units was somewhat restricted, sign-sensitive units were found in all areas of the nE in Sternopygus. Whole-cell recordings made in the nE of Eigenmannia revealed that, as in Sternopygus, sign-sensitive cells were not restricted to areas associated with control of the JAR. The diverse neurophysiology and connectivity of the nucleus electrosensorius suggests that, besides its role in the JAR of some members of the order, this nucleus likely serves as an interface between sensory input and neural circuits controlling other behaviors and endocrinological states in other gymnotiforms as well. The discovery of sign sensitivity in the nE of Sternopygus indicates that this property is not uniquely associated with the presence of a JAR; rather, the ability to discriminate the sign of DF may be relevant to many other behavioral contexts in gymnotiforms. Existing evidence indicates that the JAR evolved more than once in this group; the presence of sign sensitivity in ancestral gymnotiforms may have made this parallelism more likely.

Animals↗

PubMed2004

Insights into neural mechanisms and evolution of behaviour from electric fish.

Both behaviour and its neural control can be studied at two levels. At the proximate level, we aim to identify the neural circuits that control behaviour and to understand how information is represented and processed in these circuits. Ultimately, however, we are faced with questions of why particular neural solutions have arisen, and what factors govern the ways in which neural circuits are modified during the evolution of new behaviours. Only by integrating these levels of analysis can we fully understand the neural control of behaviour. Recent studies of electrosensory systems show how this synthesis can benefit from the use of tractable systems and comparative studies.

Animals↗

PubMed2003

Voltage-gated Na+ channels enhance the temporal filtering properties of electrosensory neurons in the torus.

Regenerative processes enhance postsynaptic potential (PSP) amplitude and behaviorally relevant temporal filtering in more than one-third of electrosensory neurons in the torus semicircularis of Eigenmannia. Data from in vivo current-clamp intracellular recordings indicate that these "regenerative PSPs" can be divided in two groups based on their half-amplitude durations: constant duration (CD) and variable duration (VD) PSPs. CD PSPs have half-amplitude durations of between 20 and 60 ms that do not vary in relation to stimulus periodicity. In contrast, the half-amplitude durations of VD PSPs vary in relation to stimulus periodicity and range from approximately 10 to 500 ms. Injection of 0.1 nA sinusoidal current through the recording electrode demonstrated that CD PSPs and not VD PSPs can be elicited by voltage fluctuations alone. In addition, CD PSPs were blocked by intracellular application of either QX-314 or QX-222, whereas VD PSPs were not. These in vivo data suggest, therefore, that CD PSPs are mediated by voltage-dependent Na+ conductances.

Action Potentials↗

PubMed2002

Auditory midbrain neurons that count.

Many acoustic communication signals, including human speech and music, consist of a precise temporal arrangement of discrete elements, but it is unclear whether this precise temporal patterning is required to activate the sensory neurons that mediate signal recognition. In a variety of systems, neurons respond selectively when two or more sound elements are presented in a particular temporal order and the precise relative timing of these elements is particularly important for 'delay-tuned' neurons, including 'tracking' types, in bats. Here we show that one class of auditory neurons in the midbrain of anurans (frogs and toads) responds only to a series of specific interpulse intervals (IPIs); in the most selective cases, a single interval that is slightly longer or shorter than the requisite interval can reset this interval-counting process.

Acoustic Stimulation↗

PubMedDate not supplied

Roles for short-term synaptic plasticity in behavior.

Short-term synaptic plasticity is phylogenetically widespread in ascending sensory systems of vertebrate brains. Such plasticity is found at all levels of sensory processing, including in sensory cortices. The functional roles of this apparently ubiquitous short-term synaptic plasticity, however, are not well understood. Data obtained in midbrain electrosensory neurons of Eigenmannia suggest that this plasticity has at least two roles in sensory processing; enhancing low-pass temporal filtering and generating phase shifts used in processing moving sensory images. Short-term synaptic plasticity may serve similar roles in other sensory modalities, including vision.

Animals↗