¹Yale University, Psychiatry, New Haven, United States, ²Yale University, Neuroscience, New Haven, United States, ³University of Pittsburgh, Psychiatry, Pittsburgh, United States

Background: The recently evolved dorsolateral prefrontal cortex (DLPFC) is essential to higher cognition, working memory and abstract thought, with pyramidal cell microcircuits in layer III that are able to excite each other to keep information “in mind” without sensory stimulation^1,2. However, these pyramidal cells are remarkably susceptible in neuropsychiatric disorders, where layer III is the focus of synapse dendritic atrophy in schizophrenia and neurodegenerative disorders such as Alzheimer’s disease (AD), where it highly correlates with degree of cognitive impairment^3-6. Mutations in CACNA1G and CACNA1C, which encode the T-type (Cav3.1) and L-type (Cav1.2) voltage-gated calcium channels, are strongly associated with risk for mental disorders^7-10. However, it remains unclear why these channels are so critical for cognition, and whether they directly affect the vulnerable layer III pyramidal neurons of the DLPFC that are central to working memory.

Aims & Objectives: This study aimed to define the molecular and physiological mechanisms by which calcium channel signaling supports the specialized function of layer III DLPFC pyramidal neurons in primates. We sought to (1) integrate transcriptomic data from human and macaque DLPFC to identify voltage-gated calcium channel signatures of vulnerable pyramidal cell populations; (2) map the anatomical, subcellular, and cell-type–specific distribution of Cav3.1 and Cav1.2 channels in macaque cortex; and (3) determine how these channels regulate persistent neuronal firing essential for working memory.

Method: We combined transcriptomic analyses from human and macaque DLPFC with anatomical, molecular, and electrophysiological approaches in macaques, including assessments of connectivity, subcellular localization, cell-type–specific protein expression, and neuronal physiology.

Results: Layer III DLPFC pyramidal neurons displayed a calcium-centered functional interactome with elevated CACNA1G and CACNA1C expression, and prominent Cav3.1 and Cav1.2 protein localization within dendritic spines adjacent to endoplasmic reticulum calcium stores. CACNA1G was enriched in human layer III pyramidal cells, with Cav3.1 channels observed presynaptically on glutamatergic terminals, and postsynaptically on dendritic spines—both at synaptic and extrasynaptic sites—as well as on dendritic shafts. Electrophysiology showed that Cav3.1 and Cav1.2 exert strong control over the persistent neuronal firing required for working memory. Channel blockade produced an inverted-U response: high-dose inhibition reduced persistent firing, demonstrating the necessity of T-type channels, while low-dose inhibition increased firing, indicating that excessive Cav3.1 activity suppresses firing, paralleling the effects of excessive Cav1.2-dependent SK channel activation.

Discussion & Conclusions: These findings provide a mechanistic framework for understanding how either loss- or gain-of-function alterations in CACNA1G (Cav3.1) or CACNA1C (Cav1.2) disrupt the finely tuned calcium signaling required for persistent firing in layer III DLPFC pyramidal neurons. By demonstrating that both channels are strategically positioned within dendritic spines to shape calcium dynamics within nanodomains, and that their activity follows an inverted-U relationship with neuronal excitability, this work explains how deviations in either direction can abrogate microcircuit computations that support working memory. Such dysregulation offers a biologically grounded pathway linking genetic variation in calcium channel genes to DLPFC dysfunction, cognitive impairment, and increased vulnerability to schizophrenia and related neuropsychiatric disorders.