Amygdala interconnections with the cingulate motor cortex in the rhesus monkey

Authors

  • Robert J. Morecraft,

    Corresponding author
    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
    • Laboratory of Neurological Sciences, Division of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, SD 57069
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  • David W. McNeal,

    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
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  • Kimberly S. Stilwell-Morecraft,

    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
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  • Matthew Gedney,

    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
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  • Jizhi Ge,

    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
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  • Clinton M. Schroeder,

    1. Division of Basic Biomedical Sciences, Laboratory of Neurological Sciences, University of South Dakota School of Medicine, Vermillion, South Dakota 57069
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  • Gary W. van Hoesen

    1. Department of Anatomy and Cell Biology, University of Iowa College of Medicine, Iowa City, Iowa 52242
    2. Department of Neurology, University of Iowa College of Medicine, Iowa City, Iowa 52242
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Abstract

Amygdala interconnections with the cingulate motor cortices were investigated in the rhesus monkey. Using multiple tracing approaches, we found a robust projection from the lateral basal nucleus of the amygdala to Layers II, IIIa, and V of the rostral cingulate motor cortex (M3). A smaller source of amygdala input arose from the accessory basal, cortical, and lateral nuclei, which targeted only the rostral region of M3. We also found a light projection from the lateral basal nucleus to the same layers of the caudal cingulate motor cortex (M4). Experiments examining this projection to cingulate somatotopy using combined neural tracing strategies and stereology to estimate the total number of terminal-like immunoreactive particles demonstrated that the amygdala projection terminates heavily in the face representation of M3 and moderately in its arm representation. Fewer terminal profiles were found in the leg representation of M3 and the face, arm, and leg representations of M4. Anterograde tracers placed directly into M3 and M4 revealed the amygdala connection to be reciprocal and documented corticofugal projections to the facial nucleus, surrounding pontine reticular formation, and spinal cord. Clinically, such pathways would be in a position to contribute to mediating movements in the face, neck, and upper extremity accompanying medial temporal lobe seizures that have historically characterized this syndrome. Alterations within or disruption of the amygdalo-cingulate projection to the rostral part of M3 may also have an adverse effect on facial expression in patients presenting with neurological or neuropsychiatric abnormalities of medial temporal lobe involvement. Finally, the prominent amygdala projection to the face region of M3 may significantly influence the outcome of higher-order facial expressions associated with social communication and emotional constructs such as fear, anger, happiness, and sadness. J. Comp. Neurol. 500:134–165, 2007. © 2006 Wiley-Liss, Inc.

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