J Affect Disord
April 1, 2018
Facundo Carrillo, Mariano Sigman, Diego Fernández Slezak et al.
57 citations
An algorithm analyzing natural speech from baseline interviews can predict which patients with treatment-resistant depression will respond to psilocybin therapy. The approach uses vocal patterns and linguistic features to forecast treatment outcomes, suggesting that speech biomarkers may enable personalized medicine in mental health. This predictive capability could help identify likely responders before treatment begins, advancing precision psychiatry for depression.
Conscious Cogn
December 8, 2020
Camila Sanz, Carla Pallavicini, Facundo Carrillo et al.
34 citations
Language produced under the influence of LSD shows increased entropy and reduced semantic coherence, consistent with a state of heightened neural entropy. Non-semantic analysis of speech organization revealed increased verbosity and a reduced lexicon, changes more similar to manic psychoses than to schizophrenia, as confirmed by direct comparison with reference samples. Features related to language organization allowed machine learning classifiers to identify speech under LSD with accuracy comparable to that obtained by examining semantic content. These results provide a quantitative characterization of disorganized natural speech as a landmark feature of the psychedelic state.
Cortex; a journal devoted to the study of the nervous system and behavior
September 1, 2021
Santiago Alcaide, Jacobo Sitt, Tomoyasu Horikawa et al.
13 citations
Waking up from early sleep involves a two-stage brain process. First, subcortical and sensorimotor structures activate before most cortical regions, followed by rapid whole-brain activation, with frontal regions engaging slightly later. A second, slower stage may then occur, where cortical regions activate before subcortical structures and the cerebellum. This pattern suggests subcortical structures play a key role in initiating and maintaining conscious states.
Neuroimage
October 17, 2022
Natália Bezerra Mota, Ernesto Soares, Edgar Altszyler et al.
5 citations
Visual and emotional aspects of waking memories follow different paths as people fall asleep. Healthy adults viewed an emotional image, then were awakened seconds to minutes later during wakefulness, N1, or N2 sleep stages. Semantic similarity between the image and subsequent hypnagogic imagery—the 'image residue'—persisted and even increased during N1 sleep, lasting longer with more time in that stage. In contrast, the emotional tone of the image—the 'affect residue'—gradually faded as sleep progressed, becoming neutralized and reaching its lowest point during N2. Brain theta power (4.5–6.5 Hz) during N1 was inversely related to image residue. These findings suggest that visual content and strong negative emotions may decouple at sleep onset, possibly aiding emotional processing.
Neuroimage
April 1, 2018
Ezequiel Mikulan, Eugenia Hesse, Lucas Sedeño et al.
Gamma-band neural synchrony is thought to be important for cortical computation and consciousness, but prior evidence has been inconclusive due to methodological issues. By using intracranial EEG in three participants with implanted electrodes, researchers compared high-gamma connectivity (90-120 Hz) during passive wakefulness versus non-REM sleep. Connectivity and graph-theory measures were higher during wakefulness and distinguished the two states better than other frequency bands. This is the first intracranial EEG report of wake-sleep differences in high-gamma activity at both local and distant brain sites, highlighting the technique's value for studying neural correlates of consciousness.
Consciousness and Cognition
November 1, 2017
Edgar Altszyler, Sidarta Ribeiro, Mariano Sigman et al.
Word-embedding techniques, which quantify word associations in text, can identify patterns in dream reports even when the dataset is small. Latent Semantic Analysis (LSA) outperformed Skip-gram in extracting semantic associations from small corpora in two tests. LSA captured relevant word associations in dream collections, including cases with low-frequency words or few dreams. This approach offers a complementary method to traditional frequency-based dream content analysis and opens new avenues for dream interpretation and decoding.
arXiv Preprint Archive
October 5, 2016
Edgar Altszyler, Mariano Sigman, Sidarta Ribeiro et al.
Word embeddings are typically studied in large text datasets, but few studies examine small corpora like single-person text production. This paper compares Skip-gram and LSA for extracting semantic patterns from small dream report series. LSA outperformed Skip-gram on small training corpora in two semantic tests. As a case study, LSA captured relevant word associations in dream reports even with few dreams or low-frequency words. The authors propose LSA can explore word associations in dream reports, offering new insights for psychology research.
Behavioral and brain functions : BBF
December 23, 2013
Margherita Melloni, Lucas Sedeño, Blas Couto et al.
Long-term and short-term meditators showed lower anxiety and depression than non-meditators, but no improvement in executive function or social cognition, except for lower personal distress scores on empathy. Meditators did not differ from non-meditators in cardiac interoceptive sensitivity, measured by a heartbeat detection task. The authors suggest that mindfulness meditation may not influence cardiac interoception, possibly because awareness of heartbeat sensations is not emphasized in mindfulness or vipassana practice.
Neuroimage
February 1, 2012
Sebastien Marti, Mariano Sigman, Stanislas Dehaene
The psychological refractory period (PRP) and attentional blink (AB) are two well-known phenomena that limit the ability to process two successive tasks or stimuli. A neuromimetic model proposed they might share a common bottleneck—a serial stage where stimuli gain access to consciousness. Using magneto-encephalography (MEG) in a cross-modal paradigm with an auditory first target and a visual second target, the authors observed both PRP (delayed processing) and AB (missed detection) on different trials with identical stimuli. Brain recordings showed identical early sensory processing in visual cortices for both trial types, but later frontal activations (>350 ms) were delayed in PRP trials and absent in blinked trials. The results indicate that both phenomena arise from the same cortical stages and are distinguished by trial-by-trial fluctuations in task processing.