Neural oscillations
202308162003
Slow oscillatory activity reflects alternating periods of activity and silence (“up and down states”) of cortico-thalamo-cortical networks resulting from synchronized changes in membrane potential and synaptic activity of neuronal ensembles (src: Nichols2016)
Oscillations in the brain display harmonics, where higher frequency oscillations are nested within lower frequencies (Jensen2007).
(8-12Hz)
Summary
The alpha rhythm likely arises from the synchronous activity of thalamic pacemaker cells. It’s most reliably recorded in the occipital cortex during wakeful, eyes-closed rest.
- Thought to be related to temporal framing in perceptual processing (Lorincz2009, Klimesch2011 (src: Carhart-Harris2014))
- Positive relationship found b/w self-reflection and power (Knyazev2011 and synchronization during rest and BOLD activity in regions of the DMN (Jann2009])
- Mature developmentally and evolutionarily (Basar2009, src: Carhart-Harris2014)
- Decrease in the PCC after psilocybin (Carhart-Harris2014), correlates with ego dissolution.
- Thought to reflect a state of enhanced cortical excitability (Muller2013)
- Top-down inhibition (Klimesch2007) and more specifically, conferring top-down expectations about perceptual stimuli (Mayer2016)
- Correlates positively with DMN activity (Mantini2007)
- ! Cross-cultural EEG study showed that is most pronounced in the most technologically advanced cultures (N=400) (Parameshwaran2017)
- Top-down inhibition of motor control (Fries2015)
- Intracranial recordings from ventral PCC in humans show dominance of theta (Foster2012)
- Modulate amplitude of high- oscillations and magnitude of coupling fluctuates at frequency consistent with spontaneous BOLD signal fluctuations (~0.1Hz)
- Canonical rhythm of the Hippocampus (Buzsaki2002)