Spindle neurons of the human anterior cingul. Ate cortex

Abstract

The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer-assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triple was present in a large percentage of these neurons and that they did not contain calcium-binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.

The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

“…The VENs are also reduced in FI ). In contrast, Seeley et al (2006Seeley et al ( , 2007 found that the VENs were not significantly reduced in Alzheimer's dementia (AD) although a reduction had been reported in an earlier study which did not use stereological methods (Nimchinsky et al 1995). Rankin et al (2006) systematically investigated the capacity for empathic concern in a large population of neurological patients and found that this capacity was greatly reduced in FTD patients; while this capacity was variably expressed in Alzheimer's patients it was not significantly reduced relative to neurologically normal controls.…”

“…SAI appears to correspond to Rose's (1928) granular insular areas (i7, i8, and i9). The cytoarchitecture of area LA and the location of the VENs in this area of anterior cingulate cortex are illustrated in von Economo (2009) and Nimchinsky et al (1995Nimchinsky et al ( , 1999.…”

“…Rose (1927) additionally described cells of this type in anterior cingulate cortex of a chimpanzee brain. They have often been termed ''spindle cells'' (Nimchinsky et al 1995;, but because of possible confusion with other uses of this term, we have opted to call then von Economo neurons or VENs.…”

“…This architecture suggests that these cells may be comparing inputs to these two symmetrical dendrites (Watson et al 2006). The VENs in LA are filled retrogradely with the carbocyanin tracer DiI after it is deposited in the cingulum bundle, and thus the VENS are likely to be projection neurons with axonal connections extending through the underlying white matter to other parts of the brain (Nimchinsky et al 1995). The large size of the VENs and their preferential staining with the antibody for non-phosphorylated neurofilament are also characteristic features of cortical projection neurons (Nimchinsky et al 1995;Allman et al 2002).…”

Von Economo Neurons in the Elephant Brain

“…The VENs are more numerous in humans than in apes and may be part of the neural circuitry supporting complex social behavior in hominids (great apes and humans). The large size of the VENs, the morphological simplicity of their dendritic architecture, and many other features suggest that they are specialized for rapid transmission of information over long distances (Hofman et al, 1987;Nimchinsky et al, 1995;Allman et al, 2002). The bipolar dendrites of VENs are shaped and positioned to integrate information from an entire cortical minicolumn and to rapidly relay output to other brain structures (Watson et al, 2006).…”