Mapping the Early Developmental Timeline for Auditory Neural Coding
Bahar Saadatmehr, Mohammadreza Edalati, Fabrice Wallois, Ghida Ghostine, Guy Kongolo et al.
(see article e0398242024)
An important stage of mammalian neurodevelopment is the onset of sound and auditory rhythm processing by the brain. The human brain responds to sounds as early as the beginning of the third trimester of pregnancy. To extend this finding in a new study, Saadatmehr et al. explored the development by the end of pregnancy. They used EEG to measure neural responses of prematurely born babies exposed to auditory rhythms. These recordings started at the age in which the human cortex becomes more responsive to the outside world (28 weeks gestational age) and continued until the prematurely born babies reached the age equivalent of full-term pregnancy. The authors discovered that the brain got better at following rhythmic structure with increasing gestational age. By the time the babies reached the age equivalent of full-term pregnancy, their neural oscillations entrained to auditory rhythms similarly to adults. According to the authors, this is the first demonstration of the early developmental timeline for the neural coding of sound and auditory rhythm.
Topographical scalp distributions of grand average synchronization index absolute values for beat-related frequencies. See Saadatmehr et al. for more information.
Heterogeneous Fast-Spike Interneuron Response Properties
Chuyi Su, Rosangela F. Mendes-Platt, Jose Manuel Alonso, Harvey A. Swadlow, and Yulia Bereshpolova
(see article e1116242024)
There are many fast-spiking interneurons throughout the layers of the visual cortex, but they may have different response properties and functions. Su et al. provide valuable insight into the heterogeneity of fast-spiking interneurons in this issue. Informed by previous work exploring inputs to interneurons in layer 4 of the visual cortex, the authors explored the functional properties and thalamic inputs to putative fast-spiking interneurons in layer 5 of the rabbit visual cortex in vivo. They discovered that some layer 5 interneurons receive powerful input from the lateral geniculate nucleus of the thalamus. Compared with previously collected data in layer 4, these interneurons bared more similar response properties to layer 4 interneurons than did layer 5 interneurons with little direct thalamic input. Interneurons with less thalamic input had sharper orientation tuning, longer visual response latencies, lower spontaneous and visually driven firing rates, and were located deeper in layer 5. The detailed thalamocortical analyses and results from this study may be translatable to other animal models and to other sensory circuits.
Footnotes
This Week in The Journal was written by Paige McKeon