Oscillatory gamma activity in humans: a possible role for object representation

Bertrand, Olivier; Tallon‐Baudry, Catherine

doi:10.1016/s0167-8760(00)00166-5

Cited by 269 publications

(156 citation statements)

References 43 publications

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“…According to a celebrated hypothesis (Singer 1993;von der Malsburg and Schneider 1986) rhythmic synchronization in the gamma-band would permit the solution of the binding and segmentation problem, i.e., it allows different objects to be simultaneously held in memory avoiding misinterpretations. Experimental evidence supporting this hypothesis for object recognition has been given, not only for what concerns bottom-up processing but also internally driven representations (Bertrand and Tallon-Baudry 2000). Furthermore, gamma-band synchronization agrees with recent temporal rules of Hebbian potentiation (Abbott and Nelson 2000;Markram et al 1997).…”

Section: Discussionsupporting

confidence: 52%

An integrated neural model of semantic memory, lexical retrieval and category formation, based on a distributed feature representation

2011

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This work presents a connectionist model of the semantic-lexical system. Model assumes that the lexical and semantic aspects of language are memorized in two distinct stores, and are then linked together on the basis of previous experience, using physiological learning mechanisms. Particular characteristics of the model are: (1) the semantic aspects of an object are described by a collection of features, whose number may vary between objects. (2) Individual features are topologically organized to implement a similarity principle. (3) Gamma-band synchronization is used to segment different objects simultaneously.(4) The model is able to simulate the formation of categories, assuming that objects belong to the same category if they share some features. (5) Homosynaptic potentiation and homosynaptic depression are used within the semantic network, to create an asymmetric pattern of synapses; this allows a different role to be assigned to shared and distinctive features during object reconstruction. (6) Features which frequently occurred together, and the corresponding word-forms, become linked via reciprocal excitatory synapses. (7) Features in the semantic network tend to inhibit words not associated with them during the previous learning phase. Simulations show that, after learning, presentation of a cue can evoke the overall object and the corresponding word in the lexical area. Word presentation, in turn, activates the corresponding features in the sensorymotor areas, recreating the same conditions occurred during learning, according to a grounded cognition viewpoint. Several words and their conceptual description can coexist in the lexical-semantic system exploiting gamma-band time division. Schematic exempla are shown, to illustrate the possibility to distinguish between words representing a category, and words representing individual members and to evaluate the role of gamma-band synchronization in priming. Finally, the model is used to simulate patients with focalized lesions, assuming a damage of synaptic strength in specific feature areas. Results are critically discussed in view of future model extensions and application to real objects. The model represents an original effort to incorporate many basic ideas, found in recent conceptual theories, within a single quantitative scaffold.

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Section: Discussionsupporting

confidence: 52%

An integrated neural model of semantic memory, lexical retrieval and category formation, based on a distributed feature representation

2011

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“…Given that the modulation of gamma bands plays a role in linking different brain areas involved in object representation as well as in unifying coherent percepts and in focusing the top-down flow of attentional mechanisms (Bertrand and Tallon-Baudry, 2000) it could be suggested that, perhaps independently by the antiepileptic mechanism, these effects might contribute to the improvement of the quality of life in epileptic subjects as well as in depressed patients.…”

Section: Discussionmentioning

confidence: 99%

Increase in 20–50Hz (gamma frequencies) power spectrum and synchronization after chronic vagal nerve stimulation

Marrosu¹,

Santoni²,

Puligheddu³

et al. 2005

Clinical Neurophysiology

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Objective: Though vagus nerve stimulation (VNS) is an important option in pharmacoresistant epilepsy, its mechanism of action remains unclear. The observation that VNS desynchronised the EEG activity in animals suggested that this mechanism could be involved in VNS antiepileptic effects in humans. Indeed VNS decreases spiking bursts, whereas its effects on the EEG background remain uncertain. The objective of the present study is to investigate how VNS affects local and inter regional syncronization in different frequencies in pharmacoresistent partial epilepsy. Methods: Digital recordings acquired in 11 epileptic subjects 1 year and 1 week before VNS surgery were compared with that obtained 1 month and 1 year after VNS activation. Power spectrum and synchronization were then analyzed and compared with an epileptic group of 10 patients treated with AEDs only and with 9 non-epileptic patients. Results: VNS decreases the synchronization of theta frequencies (P!0.01), whereas it increases gamma power spectrum and synchronization (!0.001 and 0.01, respectively). Conclusions: The reduction of theta frequencies and the increase in power spectrum and synchronization of gamma bands can be related to VNS anticonvulsant mechanism. In addition, gamma modulation could also play a seizure-independent role in improving attentional performances. Significance: These results suggest that some antiepileptic mechanisms affected by VNS can be modulated by or be the reflection of EEG changes. q

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Section: Introductionmentioning

confidence: 99%

“…Tallon-Baudry et al, 1996, 2003Gruber et al 2004Gruber et al , 2005Rodriguez et al 1999) explored activity in a range of frequencies higher than 20 Hz, which were addressed as "gamma-band". Specifically, many studies have associated between high-level perceptual mechanisms and the so-called "induced" gamma-band activity (iGBA; for review see Bertrand and Tallon-Baudry, 2000).iGBA is a measure for local neural synchronization appearing as bursts of high-frequency EEG activity which is event-related but is not necessarily phase locked to the stimulus onset (and thus may be cancelled out in traditional ERP analysis). The amplitude of these bursts is modulated by physical stimulus attributes such as size, contrast and spatial-frequency spectrum…”

mentioning

confidence: 99%

Human face preference in gamma-frequency EEG activity

et al. 2008

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Previous studies demonstrated that induced EEG activity in the gamma band (iGBA) plays an important role in object recognition and is modulated by stimulus familiarity and its compatibility with pre-existent representations. In the present study we investigated the modulation of iGBA by the degree of familiarity and perceptual expertise that observers have with stimuli from different categories. Specifically, we compared iGBA in response to human faces versus stimuli which subjects are not expert with (ape faces, human hands, buildings and watches). iGBA elicited by human faces was higher and peaked earlier than that elicited by all other categories, which did not differ significantly from each other. These findings can be accounted for by two characteristics of perceptual expertise. One is the activation of a richer, stronger and, therefore, more easily accessible mental representation of human faces. The second is the more detailed perceptual processing necessary for within-category distinctions, which is the hallmark of perceptual expertise. In addition, the sensitivity of iGBA to human but not ape faces was contrasted with the face-sensitive N170-effect, which was similar for human and ape faces. In concert with previous studies, this dissociation suggests a multi-level neuronal model of face recognition, manifested by these two electrophysiological measures, discussed in this paper.Cognitive neuroscience research has been enriched during the last decade by studies associating high-frequency EEG activity with the generation of unified perceptual representations in both vision and audition, and the activation of pre-stored memory representations (Busch, et al., 2006;Kaiser and Lutzenberger, 2003). Changing the conception that physiologically pertinent EEG frequencies are lower than 20 Hz, studies in animals (Singer and Gray, 1995) and in humans (e.g. Tallon-Baudry et al., 1996, 2003Gruber et al. 2004Gruber et al. , 2005Rodriguez et al. 1999) explored activity in a range of frequencies higher than 20 Hz, which were addressed as "gamma-band". Specifically, many studies have associated between high-level perceptual mechanisms and the so-called "induced" gamma-band activity (iGBA; for review see Bertrand and Tallon-Baudry, 2000).iGBA is a measure for local neural synchronization appearing as bursts of high-frequency EEG activity which is event-related but is not necessarily phase locked to the stimulus onset (and thus may be cancelled out in traditional ERP analysis). The amplitude of these bursts is modulated by physical stimulus attributes such as size, contrast and spatial-frequency spectrum

show abstract

Oscillatory gamma activity in humans: a possible role for object representation

Cited by 269 publications

References 43 publications

An integrated neural model of semantic memory, lexical retrieval and category formation, based on a distributed feature representation

An integrated neural model of semantic memory, lexical retrieval and category formation, based on a distributed feature representation

Increase in 20–50Hz (gamma frequencies) power spectrum and synchronization after chronic vagal nerve stimulation

Human face preference in gamma-frequency EEG activity

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