Hand-Rearing Method for Infant Marmosets

The common marmoset (Callithrix jacchus) is a small and highly social New World monkey with high reproduction rates, which has been proven to be a ...

Zhejiang University

Enhancement of Neuronal Activity in the Auditory Thalamus After Simulated Slow-Wave Oscillation.

Stigma characteristics are important factors affecting the seed yield of hybrid rice per unit area. Natural variation of stigma characteristics has been reported in rice, but the genetic basis for this variation is largely unknown. We performed a genome-wide association study on three stigma characteristics in six environments using 1.3 million single-nucleotide polymorphism (SNPs) characterized in 353 diverse accessions of Oryza sativa. An abundance of phenotypic variation was present in the three stigma characteristics of these collections. We identified four significant SNPs associated with stigma length, 20 SNPs with style length (SYL), and 17 SNPs with the sum of stigma and style length, which were detected repeatedly in more than four environments. Of these SNPs, 28 were novel. We identified two causal gene loci for SYL, OsSYL3 and OsSYL2; OsSYL3 was co-localized with the grain size gene GS3. The SYL of accessions carrying allele OsSYL3 was significantly longer than that of those carrying allele OsSYL3 . We also demonstrated that the outcrossing rate of female parents carrying allele OsSYL2 increased by 5.71% compared with that of the isogenic line carrying allele OsSYL2 in an F hybrid seed production field. The allele frequencies of OsSYL3 and OsSYL2 decreased gradually with an increase in latitude in the Northern Hemisphere. Our results should facilitate the improvement in stigma characteristics of parents of hybrid rice.

OsSYL2 , an allele identified by gene-based association, increases style length in rice (Oryza sativa L.).

Temporal processing is crucial for auditory perception and cognition, especially for communication sounds. Previous studies have shown that the auditory cortex and the thalamus use temporal and rate representations to encode slowly and rapidly changing time-varying sounds. However, how the primate inferior colliculus (IC) encodes time-varying sounds at the millisecond scale remains unclear. In this study, we investigated the temporal processing by IC neurons in awake marmosets to Gaussian click trains with varying interclick intervals (2-100 ms). Strikingly, we found that 28% of IC neurons exhibited rate representation with nonsynchronized responses, which is in sharp contrast to the current view that the IC only uses a temporal representation to encode time-varying signals. Moreover, IC neurons with rate representation exhibited response properties distinct from those with temporal representation. We further demonstrated that reversible inactivation of the primary auditory cortex modulated 17% of the stimulus-synchronized responses and 21% of the nonsynchronized responses of IC neurons, revealing that cortico-colliculus projections play a role, but not a crucial one, in temporal processing in the IC. This study has significantly advanced our understanding of temporal processing in the IC of awake animals and provides new insights into temporal processing from the midbrain to the cortex.

Corticofugal modulation of temporal and rate representations in the inferior colliculus of the awake marmoset.

Cortical feedback has long been considered crucial for the modulation of sensory perception and recognition. However, previous studies have shown varying modulatory effects of the primary auditory cortex (A1) on the auditory response of subcortical neurons, which complicate interpretations regarding the function of A1 in sound perception and recognition. This has been further complicated by studies conducted under different brain states. In the current study, we used cryo-inactivation in A1 to examine the role of corticothalamic feedback on medial geniculate body (MGB) neurons in awake marmosets. The primary effects of A1 inactivation were a frequency-specific decrease in the auditory response of most MGB neurons coupled with an increased spontaneous firing rate, which together resulted in a decrease in the signal-to-noise ratio. In addition, we report for the first time that A1 robustly modulated the long-lasting sustained response of MGB neurons, which changed the frequency tuning after A1 inactivation, e.g. some neurons are sharper with corticofugal feedback and some get broader. Taken together, our results demonstrate that corticothalamic modulation in awake marmosets serves to enhance sensory processing in a manner similar to center-surround models proposed in visual and somatosensory systems, a finding which supports common principles of corticothalamic processing across sensory systems.

Yuanqing Zhang

Zhejiang University

Hand-Rearing Method for Infant Marmosets