ScienceDaily (May 24, 2012) — Experiencing strong emotions synchronizes brain activity across individuals, a research team at Aalto University and Turku PET Centre in Finland has revealed.
Human emotions are highly contagious. Seeing others' emotional expressions such as smiles triggers often the corresponding emotional response in the observer. Such synchronization of emotional states across individuals may support social interaction: When all group members share a common emotional state, their brains and bodies process the environment in a similar fashion.
"Sharing others' emotional states provides the observers a somatosensory and neural framework that facilitates understanding others' intentions and actions and allows to 'tune in' or 'sync' with them. Such automatic tuning facilitates social interaction and group processes," says Adjunct Professor Lauri Nummenmaa from the Aalto University, Finland.
"The results have major implications for current neural models of human emotions and group behavior. It also deepens our understanding of mental disorders involving abnormal socioemotional processing," Nummenmaa says.
ScienceDaily (June 14, 2012) — Visual and auditory stimuli that elicit high levels of engagement and emotional response can be linked to reliable patterns of brain activity, a team of researchers from The City College of New York and Columbia University reports.
"Peak correlations of neural activity across viewings can occur in remarkable correspondence with arousing moments of the film," the researchers said in an article published in the journal Frontiers in Human Neuroscience. "Moreover, a significant reduction in neural correlation occurs upon a second viewing of the film or when the narrative is disrupted by presenting its scenes scrambled in time."
ScienceDaily (Aug. 12, 2012) — Major depression or chronic stress can cause the loss of brain volume, a condition that contributes to both emotional and cognitive impairment. Now a team of researchers led by Yale scientists has discovered one reason why this occurs -- a single genetic switch that triggers loss of brain connections in humans and depression in animal models.
The findings, reported in the Aug. 12 issue of the journal Nature Medicine, show that the genetic switch known as a transcription factor represses the expression of several genes that are necessary for the formation of synaptic connections between brain cells, which in turn could contribute to loss of brain mass in the prefrontal cortex.
"We wanted to test the idea that stress causes a loss of brain synapses in humans," said senior author Ronald Duman, the Elizabeth Mears and House Jameson Professor of Psychiatry and professor of neurobiology and of pharmacology. "We show that circuits normally involved in emotion, as well as cognition, are disrupted when this single transcription factor is activated."
So why has evolution equipped us with four or more senses of location?
Moser believes the ability to make a mental map of the environment arose very early in evolution. He explains that all species need to navigate, and that some types of memory may have arisen from brain systems that were actually developed for the brain's sense of location.
"We see that the grid cells that are in each of the modules send signals to the same cells in the hippocampus, which is a very important component of memory," explains Moser. "This is, in a way, the next step in the line of signals in the brain. In practice this means that the location cells send a different code into the hippocampus at the slightest change in the environment in the form of a new pattern of activity. So every tiny change results in a new combination of activity that can be used to encode a new memory, and, with input from the environment, becomes what we call memories.
About 40 percent of the cells in the hippocampus that were tagged during initial memory formation were reactivated, Wiltgen said. There was also reactivation of cells in parts of the brain cortex associated with place learning and in the amygdala, which is important for emotional memory.
There was no evidence of reactivation when the mice were tested in a new environment that they did not remember, Wiltgen said.
The researchers also looked at whether reactivation changed as memories got older. Over several weeks, reactivation in the cortex and parts of the hippocampus remained stable, but it decreased in other brain regions like the amygdala.