Prefrontal Microcircuits: Membrane Properties and Excitatory Input of Local, Medium, and Wide Arbor Interneurons

By L. Krimer, Patricia S. Goldman-Rakic. 2001

148 citations recorded by the source corpus.

To elucidate cortical mechanisms involved in higher cortical functions such as working memory, we have examined feedforward excitation transmitted by identified pyramidal cells to interneurons with predominantly horizontal axonal arbors, using dual somatic recordings in prefrontal cortical slices. Interneurons with local (narrow) axonal arbors, especially chandelier interneurons, exhibited extremely narrow action potentials and high evoked firing rates, whereas neurons identified with wide arbor axons generated wider spikes and lower evoked firing rates with considerable spike adaptation, resembling that of pyramidal cells. Full reconstruction of differentially labeled neuronal pairs revealed that local arbor cells generally received a single but functionally reliable putative synaptic input from the identified pyramidal neuron member of the pair. In contrast, more synapses (two to five) were necessary to depolarize medium and wide arbor neurons reliably. The number of putative synapses and the amplitude of the postsynaptic response were remarkably highly correlated within each class of local, medium, and wide arbor interneurons (r = 0.88, 0.95, and 0.99, respectively). Similarly strong correlations within these subgroups were also present between the number of putative synapses and variance in the EPSP amplitudes, supporting the validity of our morphological analysis. We conclude that interneurons varying in the span of their axonal arbors and hence in the potential regulation of different numbers of cortical modules differ also in their excitatory synaptic input and physiological properties. These findings provide insight into the circuit basis of lateral inhibition and functional interactions within and between cortical columns in the cerebral cortex.

Subfields: Cognitive Neuroscience, Electrical and Electronic Engineering, Statistical and Nonlinear Physics, Neuroscience

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Citations in the corpus

An Integrated Micro- and Macroarchitectural Analysis of the Drosophila Brain by Computer-Assisted Serial Section Electron Microscopy (2010, background): “Typical ‘‘microcircuits’’ in the mammalian brain, formed by multiple interconnected elements providing for stimulus convergence and divergence and inhibitory/excitatory feed forward and feed back loops, will occupy volumes of (300–1,000 mm)(3) diameter [7,57,58].”
Origins of Cortical Interneuron Subtypes (2004, background): “The interneurons, which comprise 20 –30% of cortical neurons, serve a vital role in modulating cortical output (Cherubini and Conti, 2001; Krimer and Goldman-Rakic, 2001).”
Area patterning of the mammalian cortex. (2007, background): “…interneurons, which account for about 20% of all cortical neurons, are GABAergic and also typically express distinct neuropeptides that help define subclasses (Cherubini and Conti, 2001; Krimer and Goldman-Rakic, 2001; Kawaguchi and Kondo, 2002; Butt et al., 2005; Wonders and Anderson, 2006).”
Gene Expression Deficits in a Subclass of GABA Neurons in the Prefrontal Cortex of Subjects with Schizophrenia (2003, background): “Given the heterogeneity in axonal arbors, synaptic targets, and electrophysiological properties of different subclasses of PFC GABA neurons (Lund and Lewis, 1993; Kawaguchi and Kubota, 1997; Krimer and Goldman-Rakic, 2001), identification of the affected subset is critical for understanding the neur”