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<\/p>\nThe cerebral cortex consists of two hemispheres, which are connected to each other by a white matter tract known as the corpus callosum. A specific subset of cortical neurons send axons through the corpus callosum to share information bilaterally within the two cortical hemispheres. Our lab has found that serotonin (5-HT), a ubiquitous neuromodulator in the cortex, selectively activates those cortical neurons that project across the corpus callosum to the contralateral cerebral hemisphere.<\/p>\n
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5-HT selectively excites callosal-projection neurons. A: Image of tracer injection location in the prefrontal cortex (left) and schematic of neuron labeling (right). B: Image of trace injection location in the pons (left) and schematic of neuron labeling in the prefrontal cortex(right). C: Excitatory (left) and biphasic (right) responses to focal 5-HT application in callosal projection neurons (\"COM\" neurons). D: Inhibitory responses to 5-HT in a pontine-projecting (\"CPn\") neuron. E: Proportion of callosal and pontine projecting neurons excited (red), inhibited (blue), or having biphasic (orange) responses to 5-HT. Non-responsive neurons (NR) shown in grey. F: Serotonergic excitation of callosal projection neurons (left) and inhibition of pontine-projecting neurons (right) was blocked by antagonists specific for 2A (MDL 11939) or 1A (WAY 100635) receptors, respectively.<\/p>\n
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This figure shows physiological and morphological differences in callosal projecting (\"COM\") and pontine-projecting (\"CPn\") neurons. A: Top - Responses to somatic current injections in retrograde-labeled COM and CPn L5PNs. Bottom - Comparison of input resistance (RN) in neurons having different responsiveness to 5-HT. B: Average (\u00b1 SEM) voltage responses to hyperpolarizing current injections sufficient to generate a peak hyperpolarization of ~20 mV in labeled COM and CPn neurons grouped according to 5-HT response (blue indicates inhibition, red indicates excitation, and orange indicates biphasic responses). Comparison of results is inset. C: Representative morphologies of COM and CPn neurons. D-G: Comparisons of morphological properties in COM and CPn L5PNs (n = 10 for each group). Asterisks indicate p < 0.05.<\/p>\n","protected":false},"excerpt":{"rendered":"
The cerebral cortex consists of two hemispheres, which are connected to each other by a white matter tract known as the corpus callosum. A specific subset of cortical neurons send axons through the corpus callosum to share information bilaterally within the two cortical hemispheres. Our lab has found that serotonin [\u2026] <\/p>\n