From synapse to gene product: prolonged expression of c-fos induced by a single microinjection of carbachol in the pontomesencephalic tegmentum

The Ponto-Geniculo-Occipital (PGO) Waves in Dreaming: An Overview

Rapid eye movement (REM) sleep is the main sleep correlate of dreaming. Ponto-geniculo-occipital (PGO) waves are a signature of REM sleep. They represent the physiological mechanism of REM sleep that specifically limits the processing of external information. PGO waves look just like a message sent from the pons to the lateral geniculate nucleus of the visual thalamus, the occipital cortex, and other areas of the brain. The dedicated visual pathway of PGO waves can be interpreted by the brain as visual information, leading to the visual hallucinosis of dreams. PGO waves are considered to be both a reflection of REM sleep brain activity and causal to dreams due to their stimulation of the cortex. In this review, we summarize the role of PGO waves in potential neural circuits of two major theories, i.e., (1) dreams are generated by the activation of neural activity in the brainstem; (2) PGO waves signaling to the cortex. In addition, the potential physiological functions during REM sleep dreams, such as memory consolidation, unlearning, and brain development and plasticity and mood regulation, are discussed. It is hoped that our review will support and encourage research into the phenomenon of human PGO waves and their possible functions in dreaming.

Social contact elicits immediate-early gene expression in dopaminergic cells of the male prairie vole extended olfactory amygdala

Male prairie voles (Microtus ochrogaster) are a valuable model in which to study the neurobiology of sociality because, unlike most mammals, they pair bond after mating and display paternal behaviors. Research on the regulation of these social behaviors has highlighted dopamine (DA) neurotransmission in both pair bonding and parenting. We recently described large numbers of dopaminergic cells in the male prairie vole principal nucleus of the bed nucleus of the stria terminalis (pBST) and posterodorsal medial amygdala (MeApd), but such cells were very few in number or absent in the non-monogamous species we examined, including meadow voles. This suggests that DA cells in these sites may be important for sociosexual behaviors in male prairie voles. To gain some insight into the function of these DAergic neurons in male prairie voles, we examined expression of the immediate-early genes (IEGs) Fos and Egr-1 in tyrosine hydroxylase (TH)-immunoreactive (TH-ir) cells of the pBST and MeApd after males interacted or not with one of several social stimuli. We found that IEGs were constitutively expressed in some TH-ir neurons under any social condition, but that IEG expression in these cells decreased after a 3.5-h social isolation. Thirty-minute mating bouts (but not 6- or 24-h bouts) that included ejaculation elicited greater IEG expression in TH-ir cells than did non-ejaculatory mating, interactions with a familiar female sibling, or interactions with pups. Furthermore, Fos expression in TH-ir cells was positively correlated with the display of copulatory, but not parental, behaviors. These effects of mating were not found in other DA-rich sites of the forebrain (including the anteroventral periventricular preoptic area, periventricular anterior hypothalamus, zona incerta, and arcuate nucleus). Thus, activity in DAergic cells of the male prairie vole pBST and MeApd is influenced by their social environment, and may be particularly involved in mating and its consequences, including pair bonding.