Biology subjects

Jordan, R.

Publications and source records attributed to Jordan, R..

3 recordsLinked to original sources

bioRxiv2018

Homing and egg discrimination in the Western Slimy Salamander, Plethodon albagula (Caudata: Plethodontidae)

In some species of vertebrates egg brooding is a costly form of parental care. Therefore, misdirection of parental care can significantly lower a females fitness. Because of the maternal investment and increased survivorship to offspring from egg guarding, a brooding female should home to her nest site after being displaced a short distance and discriminate between her own eggs and eggs from other females. In this study, we experimentally tested, in the field, alternative hypotheses concerning homing ability and egg discrimination in a population of nesting western slimy salamanders (Plethodon albagula). Fourteen brooding females were displaced 1 m to the left or right of their nest sites (determined randomly) for the homing experiment. Furthermore, brooding females (n = 13) were presented with their own clutches, which were displaced 50 cm to the left or right (determined randomly), and unfamiliar egg clutches at their original nest sites. The females were released at an equal distance from both egg clutches. After 24 hours, 12 displaced females (86%) had returned to their own nest sites and were brooding their egg clutches. Also, after 24 hours, nine test females had returned to their own nest sites and were brooding the unfamiliar egg clutches. No control or test females were present at the other new nest site locations. Therefore, we suggest that brooding female P. albagula do home to their nest sites and exhibit indirect egg discrimination.

animal behavior and cognition↗

bioRxiv2017

Sniff-invariant intensity perception using olfactory bulb coding of inhalation dynamics

For stable perception of odor intensity, there must exist a neural correlate that is invariant across other parameters, such as the highly variable sniff cycle. Previous hypotheses suggest that variance in inhalation dynamics alters odor concentration profiles in the naris despite a constant environmental concentration. Using whole cell recordings in the olfactory bulb of awake mice, we directly demonstrate that increased sniffing frequency mimics the effect of odor concentration increase at the level of both mitral and tufted cell (MTC) firing rate responses and temporal responses. In contrast, we find that mice are capable of discriminating concentrations within short timescales despite highly variable sniffing behavior. We reason that the only way mice can differentiate a change in sniff parameters and a change in concentration is to encode information about the inhalation parameters in parallel. While conceivably this could be achieved via corollary discharge from respiration control centres, we find that the sniff-driven activity of MTCs without odor input is informative of the kind of inhalation that just occurred, allowing rapid detection of a change in inhalation. Thus, a possible reason for sniff modulation of the early olfactory system may be to inform downstream centres of nasal flow dynamics, so that an inference can be made about environmental concentration independent of sniff variance.

neuroscience↗

bioRxiv2017

Active sampling state dynamically enhances olfactory bulb odor representation

The olfactory bulb (OB) is the very first site of odor information processing, yet a wealth of contextual and learned information has been described in its activity. To investigate the mechanistic basis of contextual modulation, we use whole-cell recordings to measure odor responses across rapid (<30 min) learning episodes in identified mitral/tufted cells (MTCs). Across these learning episodes, we found that diverse response changes occur already during the first sniff cycle. Motivated mice develop active sniffing strategies across learning, and it is this change of active sampling state that dynamically modulates odor responses, resulting in enhanced discriminability and detectability of odor representation with learning. Evoking fast sniffing in different behavioral states demonstrates that response changes during active sampling exceed those predicted from purely feed-forward input. Finally, response changes are highly correlated in tufted cells, but not mitral cells, indicating cell-type specificity in the effect of active sampling, and resulting in increased odor detectability in the tufted and enhanced discriminability in the mitral cell population over the rapid learning episodes. Altogether, we show that active sampling state is a crucial component in modulating and enhancing olfactory bulb responsiveness on rapid timescales.

neuroscience↗