#calbindin

[oaresearchpaper]

Calcium ion (Ca2+) is involved in various neurochemical signalling that contributes to neuronal activation, neurotransmitter modulation and synaptic connections. Hence, it is homeostatic regulation in the brain is of vital importance. Calcium-binding proteins (CaBPs) are key regulators of intracellular Ca2+ in the brain. The major CaBPs are calbindin, calretinin, and parvalbumin and are also markers for variety of neuronal subtypes in the brain. Understanding the distribution of brain neurons positively expressing these CaBPs as well as potential sex dimorphism in their expression is of huge relevance given their role in brain disorders. The present study examines calbindin, calretinin, and parvalbumin immunoreactivity in the cerebellum and any potential sex-specific differences. The results showed marked expression of these CaBPs in the cerebellum with calbindin and parvalbumin dominantly reactive in the molecular and Purkinje layers, and calretinin most predominant in the granular layer. Also, we see significantly higher calbindin immunoreactivity in male rats compared to female. While calretinin and parvalbumin immunoreactivity were also higher in males, this effect however did not reach significant levels. In conclusion, the present study demonstrates differential distribution patterns of the major CaBPs, calbindin, calretinin and parvalbumin, in the cerebellum and possible sex-specific differences in their immunoexpression.

[shaunicethescientist]

A dopamine gradient controls access to distributed working memory in the large-scale monkey cortex

https://www.cell.com/neuron/fulltext/S0896-6273(21)00621-8

Summary

Dopamine is required for working memory, but how it modulates the large-scale cortex is unknown. Here, we report that dopamine receptor density per neuron, measured by autoradiography, displays a macroscopic gradient along the macaque cortical hierarchy. This gradient is incorporated in a connectome-based large-scale cortex model endowed with multiple neuron types. The model captures an inverted U-shaped dependence of working memory on dopamine and spatial patterns of persistent activity observed in over 90 experimental studies. Moreover, we show that dopamine is crucial for filtering out irrelevant stimuli by enhancing inhibition from dendrite-targeting interneurons. Our model revealed that an activity-silent memory trace can be realized by facilitation of inter-areal connections and that adjusting cortical dopamine induces a switch from this internal memory state to distributed persistent activity. Our work represents a cross-level understanding from molecules and cell types to recurrent circuit dynamics underlying a core cognitive function distributed across the primate cortex.