bims-climfi 2020-08-09 papers

Issue of 2020‒08‒09
two papers selected by
Jun Maruta
Mount Sinai Health System

Brain Behav Evol. 2020 Jul 31. 1-15

Allometric Scaling Rules of the Cerebellum in Galliform Birds.

Cunha F, Racicot K, Nahirney J, Heuston C, Wylie DR, Iwaniuk AN.

Although the internal circuitry of the cerebellum is highly conserved across vertebrate species, the size and shape of the cerebellum varies considerably. Recent comparative studies have examined the allometric rules between cerebellar mass and number of neurons, but data are lacking on the numbers and sizes of Purkinje and granule cells or scaling of cerebellar foliation. Here, we investigate the allometric rules that govern variation in the volumes of the layers of the cerebellum, the numbers and sizes of Purkinje cells and granule cells and the degree of the cerebellar foliation across 7 species of galliform birds. We selected Galliformes because they vary greatly in body and brain sizes. Our results show that the molecular, granule and white matter layers all increase in volume at the same rate relative to total cerebellum volume. Both numbers and sizes of Purkinje cells increased with cerebellar volume, but numbers of Purkinje cells increased at a much faster rate than size. Granule cell numbers increased with cerebellar volume, but size did not. Sizes and numbers of Purkinje cells as well as numbers of granule cells were positively correlated with the degree of cerebellar foliation, but granule cell size decreased with higher degrees of foliation. The concerted changes among the volumes of cerebellar layers likely reflects the conserved neural circuitry of the cerebellum. Also, our data indicate that the scaling of cell sizes can vary markedly across neuronal populations, suggesting that evolutionary changes in cell sizes might be more complex than what is often assumed.

Keywords: Brain allometry; Brain evolution; Cerebellum; Comparative neuroanatomy

DOI: https://doi.org/10.1159/000509069

Neurosci Lett. 2020 Aug 02. pii: S0304-3940(20)30555-3. [Epub ahead of print] 135285

NMDARs contribute to the facial stimuli-evoked mossy fiber-granule cell synaptic transmission in vivo in mice.

Zhang XY, Zhang GJ, Li BX, Bing YH, Cui BR, Cui LN, Chu CP, Qiu DL.

N-methyl-D-aspartate receptors (NMDARs) are expressed in granule cell and involve in mossy fiber-granule cell (MF-GC) synaptic transmission in cerebellar cortex. In the absence GABAA receptor activity, we here studied the role of NMDARs during the facial stimulation evoked MF-GC synaptic transmission in urethane-anesthetized mice using electrophysiological recording technique and pharmacological methods. Our results showed that facial stimuli train (20 Hz, 5 pulses) evoked 5 field potential responses (N1-N5) in mouse cerebellar granular layer, which identified MF-GC synaptic transmission. Blocking NMDARs induced significant depression in the amplitude of N2 to N5, accompanied with significant decrease in pulse ratios, area under the curve (AUC) and half-width of N1. A selective GluN2A antagonist, PEAQX (10 µM) also produced significant depression in the amplitude of N2 to N5, and decreases in pulse ratios. However, a selective GluN2B antagonist, TCN-237 (10 µM) did not significantly attenuate the facial stimuli train-induced mossy fiber-granule cell synaptic transmission. Application of NMDA (1 μM) produced increases in the AUC and half-width of Ron, as well the amplitude and AUC of Roff, which was reversed by following application of PEAQX. Our present results indicated that NMDARs, especially GluN2A contribute to the facial stimulation-evoked MF-GC synaptic transmission, suggesting that the NMDARs play an important role during the lateral sensory information synaptic transmission in the cerebellar granular layer in vivo in mice.

Keywords: In vivo electrophysiological recording; Mossy fiber-granule cell synaptic transmission; N-methyl-d-aspartate receptors (NMDARs); Neuropharmacology; Sensory stimulation

DOI: https://doi.org/10.1016/j.neulet.2020.135285