Amygdala interconnections with the cingulate motor cortex in the rhesus monkey

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.

Connectivity-Based Parcellation of Human Cingulate Cortex and Its Relation to Functional Specialization

“…This may, however, just reflect these small size of the areas, their proximity to the corpus callosum, and the care taken to avoid including callosal tissue in the cingulate mask. In addition, although an area with a high amygdala connection probability was identified that resembled the core amygdala-connecting region in macaque, there was no strong evidence for interconnection between dorsal cingulate motor regions and amygdala in the present study, although such connections exist, albeit at a lower density, in the macaque (Morecraft et al, 2007). It should, however, be noted that the region identified as interconnected with amygdala in the present study resembles that found to vary in tandem with amygdala in morphometric analyses of the human brain (Pezawas et al, 2005).…”

“…The probability of connections between cingulate and amygdala was assessed because, in the monkey, the amygdala is interconnected with anterior cingulate cortex (Porrino et al, 1981;Amaral and Price, 1984;Carmichael and Price, 1995;Ghashghaei et al, 2007;Morecraft et al, 2007).…”

Frontal Cortex Subregions Play Distinct Roles in Choices between Actions and Stimuli

“…The shared involvement of OFC and ACC S in reinforcementguided decision making is consistent with the areas' shared anatomical connections with brain structures critical for reinforcement learning such as the amygdala and ventral striatum (Porrino et al, 1981;Morecraft et al, 2007). The differences in OFC and ACC S function are also, however, consistent with differences in their relative strength of connection with sensory and motor systems.…”

Parallel Processing of Nociceptive A-δ Inputs in SII and Midcingulate Cortex in Humans

“…Alternatively, the late pMCC response may reflect an integrative response to inputs reaching the pMCC through multisynaptic corticocortical connections from both sensory and associative areas. Indeed, the pMCC receives inputs from multiple cortical sources, including other subregions of CC, posterior parietal cortex, insula, amygdala, and motor and premotor cortices, and sends back projections to most of them (Baleydier and Mauguière, 1980;Morecraft and Van Hoesen, 1992Hatanaka et al, 2003;Morecraft et al, 2007).…”