ReviewEEG alpha oscillations: The inhibition–timing hypothesis
Section snippets
Introduction: basic principles underlying the inhibition–timing hypothesis
Osocillations reflect rhythmic changes in the (relative) level of depolarization in the (dendritic and somatic) membrane potentials of masses of neurons. Consequently, they reflect phases of low versus high excitability. The basic principle (shown in Fig. 1) can be illustrated by considering the phase of oscillatory activity together with the level of excitation in excitatory neurons. For simplicity, we assume that oscillatory activity is induced by inhibitory cells and reflects rhythmic
Alpha desynchronization (ERD) as a functional correlate of brain activation
The well-known alpha response – power suppression during eyes opening (described since the early days of EEG research, cf. Berger, 1929) – suggests that light stimulation (bottom-up processing) is responsible for the decrease of the large amplitudes which can be observed particularly at posterior recording sites during closed eyes. Most interestingly, this interpretation is questioned by the simple fact that alpha suppression can also be observed solely in response to eyes opening (a top-down
The timing aspect
As discussed in Section 2, an increase in rhythmic activity results in two different effects, in a general decrease in firing rate and an increase in rhythmic discharges (cf. Figs. 1A with B). We assume that the first effect reflects inhibition as discussed in Section 3. The second effect, however, underlies the timing of neuronal activity and will be discussed in this section.
The crucial aspect – as outlined in Fig. 1 – is that an increase in inhibition (driving an oscillation) is accompanied
The physiological basis of alpha oscillations
Since several decades, it was suggested that the thalamus plays a key role in the generation of cortical oscillations and sleep spindles in particular (Andersen and Andersson, 1968). Thus, it was tempting to assume that alpha, as the dominant oscillation in the human scalp EEG, also is generated by thalamic nuclei. This view has led to the idea that the cortex might be passively driven by a ‘thalamic pacemaker’ (cf. Basar et al., 1997, for a review). The seminal work by Lopes da Silva et al.,
Elaboration of the alpha inhibition–timing (AIT) hypothesis and critical questions
We have focused on two basic aspects, one referring to the state, the other to the timing of information processing. With respect to the first aspect, experimental evidence shows consistently that ERD reaches a maximum during a time window in which (conscious) task-related processes take place, whereas ERS can be observed when certain aspects of task performance are under top-down control. Although both cases reflect states of information processing, their functional difference can be best
Conclusions
The general line of our argumentation is that alpha – like other oscillations – is an active phenomenon but reflects – in contrast to other oscillations, a certain type of top-down process. The active role of alpha is seen in a mechanism that also may underlie the functional role of other oscillations: Synchronization in the alpha frequency range helps neurons in distributed networks to effectively activate common target cells. We think that this timing mechanism plays an important role in the
Acknowledgment
This research was supported by the Austrian Science Fund (FWF), P-16849-B022.
References (190)
- et al.
Figuring space by time
Neuron
(2001) - et al.
EEG alpha activity and the ERP to target stimuli in an auditory oddball paradigm
Int. J. Psychophysiol.
(2000) - et al.
Event-related potentials in the auditory oddball as a function of EEG alpha phase at stimulus onset
Clin. Neurophysiol.
(2004) - et al.
Alpha oscillations in brain functioning: an integrative theory
Int. J. Psychophysiol.
(1997) - et al.
Paradox lost? Exploring the role of alpha oscillations during externally vs. internally directed attention and the implications for idling and inhibition hypotheses
Int. J. Psychophysiol.
(2003) - et al.
Modelling event-related responses in the brain
NeuroImage
(2005) - et al.
EEG alpha power and intelligence
Intelligence
(2002) - et al.
Intelligence related upper alpha desynchronization in a semantic memory task
Brain Res. Bull.
(2005) - et al.
Phase of alpha brain waves, reaction time and visually evoked potentials
Electroencephalogr. Clin. Neurophysiol.
(1965) - et al.
The loci of oscillatory visual-object priming: a combined electroencephalographic and reaction-time study
Int. J. Psychophysiol.
(2000)
The genesis of the EEG
Int. Rev. Neurobiol.
Alpha rhythm of the EEG modulates visual detection performance in humans
Cogn. Brain Res.
The interplay of lorazepam-induced brain oscillations: microstructural electromagnetic study
Clin. Neurophysiol.
A mechanism for cognitive dynamics: neuronal communication through neuronal coherence
Trends Cogn. Sci.
Short communication: human brain alpha rhythm: nonlinear oscillation or filtered noise?
Brain Res.
When intelligence loses is impact: neural efficiency during reasoning in a familiar area
Int. J. Psychophysiol.
Intelligence and working memory systems: evidence of neural efficiency in alpha band ERD
Cogn. Brain Res.
Intelligence and changes in regional cerebral glucose metabolic rate following learning
Intelligence
Visual discrimination performance is related to decreased alpha amplitude but increased phase locking
Neurosci. Lett.
Differential conditioning of alpha amplitude: a fresh look at an old phenomenon
Clin. Neurophysiol.
Cognitive functions of gamma-band activity: memory match and utilization
Trends Cogn. Sci.
To act or not to act: neural correlates of executive control of learned motor behavior
NeuroImage
Phase synchronization of the ongoing EEG and auditory EP generation
Clin. Neurophysiol.
Are gifted individuals less chaotic thinkers?
Pers. Individ. Differ.
Changes in cortical activity when subjects scan memory for tones
Electroencephalogr. Clin. Neurophysiol.
The dynamics of phase relationships of alpha waves during photic driving
Electroencephalogr. Clin. Neurophysiol.
EEG-alpha rhythms and memory processes
Int. J. Psychophysiol.
EEG alpha and theta oscillations reflect cognitive and memory performance: a review and analysis
Brain Res. Rev.
Episodic and semantic memory: an analysis in the EEG-theta and alpha band
Electroencephalogr. Clin. Neurophysiol.
Event-related desynchronization in the alpha band and the processing of semantic information
Cogn. Brain Res.
Brain oscillations and human memory performance: EEG correlates in the upper alpha and theta bands
Neurosci. Lett.
‘Paradoxical’ alpha synchronization in a memory task
Cogn. Brain Res.
Alpha and beta band changes in normal and dyslexic children
Clin. Neurophysiol.
Phase locked alpha and theta oscillations generate the P1-N1 complex and are related to memory performance
Cogn. Brain Res.
The phase of postural hand tremor is not influenced by repetitive photic brain stimulation
Clin. Neurophysiol.
EEG-correlated fMRI of human alpha activity
NeuroImage
The Berger rhythm: potential changes from the occipital lobes in man
Brain
Closed loop neuronal computations: focus on vibrissa somatosensation in rat
Cereb. Cortex
Face recognition in human extrastriate cortex
J. Neurophysiol.
Physiological Basis of the Alpha Rhythm
Working memory
Science
Brain Function and Oscillations, Principles and Approaches, I
Important associations among EEG-dynamics, event-related potentials, short-term memory and learning
Int. J. Neurosci.
Sensory and cognitive components of brain resonance responses
Acta Oto-laryngol., Suppl.
Super-synergy in the brain: the grandmother percept is manifested by multiple oscillations
Int. J. Chaos Bifurcation
P300 in freely moving cats with intracranial electrodes
Int. J. Neurosci.
The pharmacodynamic properties of lorazepam and methylphenidate drugs on event-related potentials and power spectral analysis in normal subjects
Clin. Electroencephalogr.
Rhythmic whisking by rat: retraction as well as protraction of the vibrissae is under active muscular control
J. Neurophysiol.
Über das Elektroenkephalogramm des Menschen
Arch. Psychiat. Nervenkr.
Cyclic change in the excitability of the optic pathway of the rabbit
Am. J. Physiol.
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