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Mechanisms and Functional Role of Internally Generated Brain Activity

Research Summary

Eva Pastalkova is studying the neuronal mechanisms that generate brain activity internally, while a rat performs a cognitive task. The influence of the external stimuli on the recorded activity is eliminated by making the stimuli stationary or irrelevant.

The brain processes a plethora of data from a variety of sources, makes multiple dependent and independent decisions, stores and calls up thoughts from the past (memories), generates thoughts, and monitors and controls bodily senses and functions, all at the same time. Many of these mental activities arise independent of external stimuli, leading to the assumption that these processes are generated internally and spontaneously. The role of this "added" network activity is more prominent in brain regions that support complex computations, such as memory, emotions, and planning. Therefore, these functions can be understood only through the mechanisms that regulate the activity of neurons within a network when a cognitive task, such as remembering, is being carried out.

My work focuses on episodic and spatial memory. I study neuronal activity in animals while they perform a memory task in an environment that reduces or eliminates external stimuli. I also study neural activity while the animals sleep.

I am particularly interested in the following questions:

1. What are the mechanisms of the internally organized activity in the dorsal and ventral hippocampus and its major input-ouput structure, the entorhinal cortex, during a hippocampus-dependent memory task?

2. What are the mechanisms organizing the spontaneous patterns of sleep, and how do they organize memories acquired during the performance of a memory task?

I study the mechanisms that internally organize neuronal activity in two ways. First, I record activity from two or more anatomically connected regions and study the relationship between the signals generated within each of these regions. Second, I interfere with the neuronal network within one region and study the consequences of this on activity in the other region. I employ various techniques to interfere with neuronal activity: light-induced excitation of channelrhodopsin-expressing neurons, light-induced suppression of halorhodopsin-expressing neurons, local change of brain temperature, and electrical stimulation.

As of September 01, 2009


Scientist Profile

Janelia Group Leader
Janelia Research Campus