CANOLTY CAL Berkeley Oscillation Phase Couples Cell Assemblies PNAS 2010

Sep 26, 2010 12:26 PM  from Cal Berkeley

PNAS;  Sept 2010; senior author is Jose Carmena at Cal Berkeley

Main author is Ryan Canolty:  post doc fellow with Jose  (formerly with Bob Knight)

note paper was edited by Nancy Kopell!

sent to me by Bernie Sept 25 2010.  he also wants to discuss with Stan Franklin.

ABSTRACT

Hebb proposed that neuronal cell assemblies are critical for effective

perception, cognition, and action. However, evidence for brainmech-

anisms that coordinate multiple coactive assemblies remains lacking.

Neuronal oscillations have been suggested as one possible mecha-

nism for cell assembly coordination. Prior studies have shown that

spike timing depends upon local !eld potential (LFP) phase proximal

to the cell body, but few studies have examined the dependence of

spiking on distal LFP phases in other brain areas far from the neuron

or the in"uence of LFP–LFP phase coupling between distal areas on

spiking. We investigated these interactions by recording LFPs and

single-unit activity using multiple microelectrode arrays in several

brain areas and then used a unique probabilistic multivariate phase

distribution to model the dependence of spike timing on the full

pattern of proximal LFP phases, distal LFP phases, and LFP–LFP phase

coupling between electrodes. Here we show that spiking activity

in single neurons and neuronal ensembles depends on dynamic

patterns of oscillatory phase coupling between multiple brain

areas, in addition to the effects of proximal LFP phase. Neurons that

prefer similar patterns of phase coupling exhibit similar changes in

spike rates, whereas neurons with different preferences show diver-

gent responses, providing a basic mechanism to bind different neu-

rons together into coordinated cell assemblies. Surprisingly, phase-

coupling–based rate correlations are independent of interneuron dis-

tance. Phase-coupling preferences correlate with behavior and neural

function and remain stable over multiple days. These f!ndings suggest

that neuronal oscillations enable selective and dynamic control of

distributed functional cell assemblies.

Experimental Data (v last para of paper):

Surgery, Electrophysiology, and Analysis. Two adult monkeys were chronically

implanted with multiple microelectrode arrays bilaterally inM1 and PMd and

performed a BMI task. Two different monkeys engaged in a working memory

task and had acute recordings made from multiple prefrontal areas. The

pairwise phase distribution of LFP measurements was modeled using a prob-

abilistic model (30). For each neuron, two models were fitted using either all

LFP data or LFP phases occurring at spike times alone and then related using

Bayes’ rule.

Page 1 

began with Hebb 60 years ago... proposal abt cell assemblies doing the work.

but how to coordinate the assemblies.

Key Q  how do diverse groups of neurons all over the cortex coordinate their activity

to form larger functional networks.

A  brain rhythms with a dynamic hierarchy of neuronal oscil, modulating local computation

and long range communication.

this hypthesis is supported by evidence that spiking activity depends on the LFP 

local field potential in both hippocampus HC and neocortex.

Single neuron spike timing depends on freq specific oscillatory LFP phase,

both proximal (close in) and at distal locations.

page 1 col 2... Look at  Fig S1 at bottom of supple material ... v easy to understand.

most spikes occur at peaks of amplitude of envelope of LFP and at indiv peaks.

supplement material graphs are excellent... pretty clear.

page 2 col 2...  "

Given the strong modulation in the high beta band for most recorded

neurons , for the M1–PMd datasets we therefore focused ex

clusively on the dependence between spikes and 36-Hz phases.

Bob note... similar to Crick/Koch 40 Hz focus.

What are the network origins of this dependence? One possi-

bility is that the spiking of this neuron is directly dependent on the

LFP activity occurring in the opposite hemisphere, perhaps medi-

ated by direct synaptic contact of projecting transcallosal axons.

Alternatively, the neuron may be directly coupled to the proximal

LFP through synaptic connections with local interneurons, but not

coupled to distal LFP signals, whereas the LFPs from proximal and

distal cortical areas are nonetheless in phase coherence. In the

second case, spikes and distal LFP phases would not be dependent

once proximal LFP phases were known—spikes and distal LFP

phases would be conditionally independent given proximal LFP

DISCUSSION:

CANOLTY CAL Berkeley Oscillation Phase Couples Cell Assemblies PNAS 2010

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