In recent years, many new cortical areas have been identified in the macaque monkey. The number of identified connections between areas has increased even more dramatically. We report here on (1) a summary of the layout of cortical areas associated with vision and with other modalities, (2) a computerized database for storing and representing large amounts of information on connectivity patterns, and (3) the application of these data to the analysis of hierarchical organization of the cerebral cortex. Our analysis concentrates on the visual system, which includes 25 neocortical areas that are predominantly or exclusively visual in function, plus an additional 7 areas that we regard as visual-association areas on the basis of their extensive visual inputs. A total of 305 connections among these 32 visual and visual-association areas have been reported. This represents 31% of the possible number of pathways if each area were connected with all others. The actual degree of connectivity is likely to be closer to 40%. The great majority of pathways involve reciprocal connections between areas. There are also extensive connections with cortical areas outside the visual system proper, including the somatosensory cortex, as well as neocortical, transitional, and archicortical regions in the temporal and frontal lobes. In the somatosensory/motor system, there are 62 identified pathways linking 13 cortical areas, suggesting an overall connectivity of about 40%. Based on the laminar patterns of connections between areas, we propose a hierarchy of visual areas and of somatosensory/motor areas that is more comprehensive than those suggested in other recent studies. The current version of the visual hierarchy includes 10 levels of cortical processing. Altogether, it contains 14 levels if one includes the retina and lateral geniculate nucleus at the bottom as well as the entorhinal cortex and hippocampus at the top. Within this hierarchy, there are multiple, intertwined processing streams, which, at a low level, are related to the compartmental organization of areas V1 and V2 and, at a high level, are related to the distinction between processing centers in the temporal and parietal lobes. However, there are some pathways and relationships (about 10% of the total) whose descriptions do not fit cleanly into this hierarchical scheme for one reason or another. In most instances, though, it is unclear whether these represent genuine exceptions to a strict hierarchy rather than inaccuracies or uncertainities in the reported assignment.

/pdf/distributed-hierarchical-processing-in-the-primate-cerebral-1dvblm6d82.pdf

Distributed Hierarchical Processing in the Primate Cerebral Cortex

Microglia: a sensor for pathological events in the CNS

Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.

Physiology of Microglia

ContextIn the intensive care unit (ICU), delirium is a common yet underdiagnosed
form of organ dysfunction, and its contribution to patient outcomes is unclear.ObjectiveTo determine if delirium is an independent predictor of clinical outcomes,
including 6-month mortality and length of stay among ICU patients receiving
mechanical ventilation.Design, Setting, and ParticipantsProspective cohort study enrolling 275 consecutive mechanically ventilated
patients admitted to adult medical and coronary ICUs of a US university-based
medical center between February 2000 and May 2001. Patients were followed
up for development of delirium over 2158 ICU days using the Confusion Assessment
Method for the ICU and the Richmond Agitation-Sedation Scale.Main Outcome MeasuresPrimary outcomes included 6-month mortality, overall hospital length
of stay, and length of stay in the post-ICU period. Secondary outcomes were
ventilator-free days and cognitive impairment at hospital discharge.ResultsOf 275 patients, 51 (18.5%) had persistent coma and died in the hospital.
Among the remaining 224 patients, 183 (81.7%) developed delirium at some point
during the ICU stay. Baseline demographics including age, comorbidity scores,
dementia scores, activities of daily living, severity of illness, and admission
diagnoses were similar between those with and without delirium (P>.05 for all). Patients who developed delirium had higher 6-month
mortality rates (34% vs 15%, P = .03) and spent 10
days longer in the hospital than those who never developed delirium (P<.001). After adjusting for covariates (including age,
severity of illness, comorbid conditions, coma, and use of sedatives or analgesic
medications), delirium was independently associated with higher 6-month mortality
(adjusted hazard ratio [HR], 3.2; 95% confidence interval [CI], 1.4-7.7; P = .008), and longer hospital stay (adjusted HR, 2.0;
95% CI, 1.4-3.0; P<.001). Delirium in the ICU
was also independently associated with a longer post-ICU stay (adjusted HR,
1.6; 95% CI, 1.2-2.3; P = .009), fewer median days
alive and without mechanical ventilation (19 [interquartile range, 4-23] vs
24 [19-26]; adjusted P = .03), and a higher incidence
of cognitive impairment at hospital discharge (adjusted HR, 9.1; 95% CI, 2.3-35.3; P = .002).ConclusionDelirium was an independent predictor of higher 6-month mortality and
longer hospital stay even after adjusting for relevant covariates including
coma, sedatives, and analgesics in patients receiving mechanical ventilation.

https://jamanetwork.com/journals/jama/articlepdf/198503/JCE30038.pdf

Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit

Degeneration and regeneration of the nervous system

https://www.cell.com/trends/neurosciences/pdf/0166-2236(88)90110-5.pdf

Macrophages and microglia in the nervous system

https://www.cns.nyu.edu/~shapley/Publications/shap-perry1986.pdf

V. Hugh Perry

Papers

Macrophages and microglia in the nervous system

Cat and monkey retinal ganglion cells and their visual functional roles

Macrophages and inflammation in the central nervous system

Macrophage dependence of peripheral sensory nerve regeneration: Possible involvement of nerve growth factor

Inflammation in the nervous system.