Biology subjects

Mpodozis, J.

Publications and source records attributed to Mpodozis, J..

4 recordsLinked to original sources

bioRxiv2025

The development of an asymmetric accessory olfactory bulb in Octodon degus and the influence of social behavior in its establishment

The vomeronasal system (VNS) has been extensively associated with the regulation of sexual and social behaviors in mammals. This system comprises two types of vomeronasal neurons sending parallel projections from the vomeronasal organ (VNO) to the anterior and posterior portions of the accessory olfactory bulb (aAOB and pAOB, respectively). Members of caviomorph rodents develop either a larger aAOB or pAOB bias, which has been associated with ecological traits related to the pheromonal communication displayed by these species. However, it is still unknown how and when such AOB asymmetries emerge and whether experience may influence their establishment. To explore these factors, we studied the development of the VNS in Octodon degus, a caviomorph that exhibits an asymmetric AOB, in which the aAOB is larger and has more glomeruli than the pAOB. We found that both VNO and AOB are present at birth, but exhibiting substantial immature traits. Both VNS structures develop postnatally, showing mature patterns by the end of the first postnatal month. By the second postnatal week, aAOB becomes larger in size than pAOB, however, in the glomerular layer such bias appears later, by the end of the first postnatal month. The AOB asymmetry increases in extent until adulthood, as in this period the pAOB shows a minor growing rate than the aAOB. Additionally, we found that animals raised in restricted social contexts displayed a reduced AOB asymmetry in comparison to wild degus. Overall, we suggest that social experiences contribute to the development of the AOB asymmetry in degus. Key pointsO_LIIn degus, the vomeronasal organ and the accessory olfactory bulb are present by birth, both displaying immature anatomical traits. More mature, adult-like vomeronasal structures are suggested to be present by the end of the first postnatal month. C_LIO_LIA bias toward a larger volume of the anterior portion of the accessory olfactory bulb compared to its posterior portion, as reported in adult degus, emerges within the first postnatal month, but continues to increase in extent until adulthood. C_LIO_LIThe AOB asymmetry is reduced in captivity-reared compared to wild-captured degus and it is absent entirely in individuals raised in isolation conditions. C_LI

neuroscience↗

bioRxiv2025

Binocular vision emerges from the coordinated development of orbit convergence, eye orientation, and high-acuity retinal specializations

Binocular vision requires both eyes to be aligned such that their visual fields overlap. A long-standing premise derived from comparative studies is that the orientation of the orbits determines eye position, and thereby the extension of this overlap, the binocular field. In addition, to produce an accurate neural representation, the binocular field must integrate with the position of retinal high-acuity areas and with the extent of uncrossed retinal projections. It remains unknown, however, whether the binocular field is already formed at the time of eye-opening, as well as when and how it integrates with neuroanatomical visual traits during development. Using the diurnal rodent Octodon degus, a suitable animal model for visual neuroscience, we combined CT-based 3D cranial reconstructions, quantitative measurements of visual-field geometry, whole-mount retinal topography, neural tracing of retinal projections, and behavioral assays to reconstruct the postnatal assembly of the binocular visual system. We show that orbital and ocular orientations shift substantially after birth, broadening the dorsal binocular field; that retinal ganglion cell distributions sharpen into a horizontal visual streak and a defined area centralis; and that ipsilateral projections to the superior colliculus mature in parallel to binocular expansion. These changes coincide with the emergence of binocular-dependent behaviors such as depth discrimination and looming-evoked escape responses. Together, our findings demonstrate that binocular vision emerges through the coordinated alignment of multiple developmental processes across levels of organization.

neuroscience↗

bioRxiv2024

Chilean brush tailed mouse (Octodon degus): a diurnal precocial rodent as a new model to study visual receptive field properties of superior colliculus neurons

Lab rodent species used to study the visual system and its development (hamsters, rats, and mice) are nocturnal, altricial, and possess simpler visual systems than carnivores and primates. To widen the spectra of studied species, here we introduce an alternative model, the Chilean degu (Octodon degus), a diurnal, precocial Caviomorph rodent with a cone enriched, well-structured retina, and well-developed central visual projections. To assess degus visual physiological properties, we characterized the visual responses and receptive field (RF) properties of isolated neurons in the superficial layers of the superior colliculus (sSC). To facilitate comparison with studies in other rodent species, we used four types of stimuli: (1) a moving white square, (2) sinusoidal gratings, (3) an expanding black circle (looming), and (4) a stationary black circle. We found that as in other mammalian species, RF size increases from superficial to deeper SC layers. Interestingly, compared to other lab rodents, degus have smaller RF sizes, likely indicating higher acuity. sSC neurons displayed spatial frequency tuning to grating stimuli from 0.08 to 0.24 cycles/degree. Additionally, neurons from sSC showed transient ON, OFF, or ON-OFF responses to stationary stimuli but increased their firing rates as a looming object increased in size. Our results suggests that degus have higher visual acuity, higher frequency tuning, and lower contrast sensitivity than commonly used nocturnal lab rodents, positioning degus as a well-suited model for studies of diurnal vision that are more relevant to humans.

neuroscience↗

bioRxiv2021

Envelope analysis of the human alpha rhythm

The origin of the human alpha rhythm has been a matter of debate since Lord Adrian attributed it to synchronous neural populations in the occipital cortex. Although some authors have pointed out the Gaussian characteristics of the alpha rhythm, their results have been repeatedly disregarded in favor of Adrians interpretation; even though the first EEG Gaussianity reports can be traced back to the origins of the field. Here we revisit this problem using the envelope analysis -- a method that relies on the fact that the coefficient of variation of the envelope (CVE) for continuous-time zero-mean Gaussian noise (as well as for any filtered sub-band) is equal to [Formula], thus making the CVE a fingerprint for Gaussianity. As a consequence, any significant deviation from [Formula] is linked to synchronous neural dynamics. We analyzed occipital EEG and iEEG data from massive public databases. Our results showed the human alpha rhythm can be characterized either as a synchronous or as a Gaussian signal based on the value of its CVE. Furthermore, Fourier analysis showed the canonical spectral peak at {approx} 10[Hz] is present in both the synchronous and Gaussian cases, thus demonstrating this same peak can be produced by different underlying neural dynamics. This study confirms the original interpretation of Adrian regarding the origin of the alpha rhythm but also opens the door for the study of Gaussianity in brain dynamics. These results suggest a broader interpretation for event-related synchronization/desynchronization (ERS/ERD) may be needed. Envelope analysis constitutes a novel complement to Fourier-based methods for neural signal analysis relating amplitude modulation patterns (CVE) to signal energy.

neuroscience↗