Cell Diversity and Connection Specificity between Callosal Projection Neurons in the Frontal Cortex

The Basal Ganglia

“…Patterns of connectivity between pyramidal neurons suggest the organization of excitatory networks that segregate functional pathways for processing different types of information (Otsuka and Kawaguchi, 2011;Morishima et al, 2011). These networks are formed by connections between cortical areas that differentially target layer 2/3 neurons and PT and IT layer 5 neurons (Mao et al, 2011), by differential connections from layer 2/3 neurons onto PT and IT layer 5 neurons (Anderson et al, 2010), and by differential probability of connections between PT and IT layer 5 neurons (Brown and Hestrin, 2009).…”

“…These networks are formed by connections between cortical areas that differentially target layer 2/3 neurons and PT and IT layer 5 neurons (Mao et al, 2011), by differential connections from layer 2/3 neurons onto PT and IT layer 5 neurons (Anderson et al, 2010), and by differential probability of connections between PT and IT layer 5 neurons (Brown and Hestrin, 2009). These distinct functional channels of excitatory networks are suggested to differentially regulate the output of PT and IT corticostriatal neurons (Morishima et al, 2011;Otsuka and Kawaguchi, 2011). These patterns of segregated excitatory circuits are proposed to underlie the integration of sensory and motor representations within motor cortical areas involved in sensorimotor learning (Huber et al, 2012).…”

Serotonin and Prefrontal Cortex Function: Neurons, Networks, and Circuits

“…Although similar in many regards, cortical pyramidal neurons are not homogenous, but have been subdivided into discrete subtypes based on morphological, physiological, and axonal target projections [22–30]. More importantly, subtypes of pyramidal neurons are very selective in their connectivity and form multiple parallel excitatory pathways within the cortical circuit that target specific cortical and subcortical structures via long-distance axonal projections [23,27–29,31]. In addition to excitatory pyramidal neurons, the PFC also contains a diverse complement of inhibitory GABAergic interneurons that are also selective in forming connections with each other and with networks of pyramidal neurons.…”

Projections, Partaken Circuits and Axon Initial Segments of Cortical Principal Neurons

“…between projection subtypes of all of these intratelencephalic cells is similar [57] [44,[54][55][56]. Principal cells of layer 6 of intratelencephalic projection have a higher probability of extending reciprocal connections between one another than with other type of projection cells.…”

“…Type II cells of layer 5 have a thick apical dendrite extending into cortical layer 1 with a prominent terminal tuft; these cells produce distinctive initial bursts of tonic firing in response to current injection [46,[53][54][55]. Depending on the cell-body position in layer 5, type I cells are characterized by having an apical dendrite that can tuft in cortical layer 1 or ascend to this layer without tufting; type I cells tend to fire phasically [44,46,[54][55][56][57]. In addition, cells of layer 5b of short apical dendrite may project to the thalamus and superior colliculus but not to the striatum [18].…”