What do you notice? https://www.youtube.com/watch?v=5v5ebf2kwf8&t=143s
Models for communication between neuron groups Communication through neuronal coherence Neuron Groups 1 and 3 send projections to Neuron Group 2 Neuron Group 1 Neuron Group 2 Neuron Group 3 Communication requires oscillatory synchrony within a region AND temporal coordination (coherence) across regions. Fries, Trends in Cognitive Science, 2005
Communication through Coherence This coherence can have a slight delay. Two brain regions that work cooperatively to process information may exhibited temporally coordinated activity in the form of coherent neural oscillations.
If we observe coherent oscillations in two different regions of the brain, what can we learn about their interactions?
A spatial working memory task: Jones and Wilson, PLOS Biology, 2005
During decision making, the prefrontal cortex might need to integrate spatial information from the hippocampus with information about routes and task rules. Entorhinal cortex Amygdala Hippocampus The prefrontal cortex receives direct projections from the hippocampus Nucleus accumbens Nucleus reuniens Jin and Maren, Front. Sys. Neuro., 2015
Simultaneous recording of neural activity in the rat prefrontal cortex and the hippocampus: A correct choice A forced choice Increases in theta coherence observed during correct choices Turn left or right (depending on the starting point) Forced run (gray) Choice run (red) 0.8mV 0.5s Jones and Wilson, PLOS Biology, 2005
Simultaneous recording of neural activity in the rat prefrontal cortex and the hippocampus: Neurons in the prefrontal cortex exhibit phase relationships to the theta rhythm in the hippocampus selectively during correct choice epochs Jones and Wilson, PLOS Biology, 2005
Synchrony between the prefrontal cortex and the hippocampus depends on ventral midline thalamus: Entorhinal cortex Amygdala The prefrontal cortex receives direct projections from the hippocampus Nucleus accumbens The prefrontal cortex does not have direct projections back to hippocampus. Nucleus reuniens Jin and Maren, Front. Sys. Neuro., 2015
Synchrony between the prefrontal cortex and the hippocampus depends on ventral midline thalamus: Inactivation of nucleus reuniens with muscimol (GABA A agonist): Theta coherence during choice points is correlated with performance in the delayed-alternation (DA) task 250ms DA = choice is based on alternation CD = choice is based on contextual discrimination Hollack et al., J. Neurosci., 2016
Synchrony between the prefrontal cortex and the hippocampus depends on ventral midline thalamus: Changes in gamma are observed first in mpfc at choice points. Changes in theta are observed first in hippocampus during start box occupancy. Hollack et al., J. Neurosci., 2016
Synchrony between the prefrontal cortex and the hippocampus depends on ventral midline thalamus: The lead in gamma by mpfc is eliminated with muscimol in nucleus reuniens. The lead in theta by hippocampus is eliminated with muscimol in nucleus reuniens. Hollack et al., J. Neurosci., 2016
Coherent oscillations can indicate (at least) the following: 1) Direct interactions (communication) and cooperative processing 2) Indirect interactions through a third region and cooperative processing 3) Interactions with a third region and independent, parallel processing
If we observe coherent oscillations in two different regions of the brain, what can we learn about their interactions?