The behavioral signature of stepwise learning strategy in male rats and its neural correlate in the basal forebrain.

Studies of associative learning have commonly focused on how rewarding outcomes are predicted by either sensory stimuli or animals' actions. However, in many learning scenarios, reward delivery requires the occurrence of both sensory stimuli and animals' actions in a specific order, in the form of behavioral sequences. How such behavioral sequences are learned is much less understood.

Synchronization across sensory cortical areas by electrical microstimulation is sufficient for behavioral discrimination.

The temporal correlation hypothesis proposes that cortical neurons engage in synchronized activity, thus configuring a general mechanism to account for a range of cognitive processes from perceptual binding to consciousness. However, most studies supporting this hypothesis have only provided correlational, but not causal evidence. Here, we used electrical microstimulation of the visual and somatosensory cortices of the rat in both hemispheres, to test whether rats could discriminate synchronous versus asynchronous patterns of stimulation applied to the same cortical sites.

Age-dependent increases in apoptosis/necrosis ratios in human lymphocytes exposed to oxidative stress.

Unlike apoptosis, mechanisms leading to necrosis are less well understood. Moreover, changes in necrosis as a function of age have not been studied in human lymphocytes. H(2)O(2)-induced death of peripheral lymphocytes (56 healthy donors, 24-95 years) was evaluated by flow cytometry and propidium iodide staining, caspase activation, DNA laddering, and electron microscopy.