This paper is a tutorial review of the structure, composition, and statistical modeling of the organization of the neocortex. It begins with a general overview of the layered structure of the neocortex and its organization as a network of interconnected functional columns. Next it discusses the various classes of neurons that populate the neocortex using as a classification system the several g...

Stem cells generate neurons in discrete regions in the postnatal mammalian brain. However, the extent of neurogenesis in the adult human brain has been difficult to establish. We have taken advantage of the integration of (14)C, generated by nuclear bomb tests during the Cold War, in DNA to establish the age of neurons in the major areas of the human cerebral neocortex. Together with the analys...

The adult mammalian neocortex consists of numerous 'areas' distinguished from one another largely on the basis of distinctions in cytoarchitecture and connections. The developing neocortex, though, lacks many of these area-specific distinctions, and is more uniform across its extent. This less differentiated structure, here termed the 'protocortex' undergoes considerable modification after neur...

A recent assertion that new neurons are continually added to the neocortex of adult macaque monkeys has profound implications for understanding the cellular mechanisms of higher cognitive functions. Here we searched for neurogenesis in adult macaques by using immunofluorescent triple labeling for the DNA-replication indicator, bromodeoxyuridine (BrdU), and neuronal and glial cell markers. Altho...

The thalamus serves as a gate that regulates the flow of sensory inputs to the neocortex, and this gate is controlled by neuromodulators from the brainstem reticular formation that are released during arousal. Here we show in rats that sensory-evoked responses were suppressed in the neocortex by activating the brainstem reticular formation and during natural arousal. Sensory suppression occurre...

Temporal lobe epilepsy (TLE) is a chronic neurodegenerative disease with a high prevalence of psychiatric disorders. Temporal neocortex contributes to either seizure propagation or generation in TLE, a situation that has been associated with alterations of the γ-amino-butyric acid (GABA) system. On the other hand, an impaired neurotransmission mediated by GABA in temporal neocortex has also bee...

During corticogenesis, cells from the medial ganglionic eminence (MGE) migrate tangentially into the neocortical anlage. Here we report that gamma-aminobutyric acid (GABA), via GABAA receptors, regulates tangential migration. In embryonic telencephalic slices, bicuculline produced an outward current in migrating MGE-derived cells in the neocortex, suggesting the presence of and tonic activation...

Long-term potentiation (LTP) and depression (LTD) are activity-dependent changes in synaptic strength that model how the brain might store memories. The mechanisms of LTP and LTD have been studied extensively in the hippocampus because the hippocampus is critical for memory storage. The neocortex is also believed to be critical for the long-term storage of memories, but less work on LTP and LTD...