bioRxiv
January 18, 2023
Cristina Delgado-Sallent, Thomas Gener, Pau Nebot et al.
preprint
In mice with NMDAR hypofunction induced by subchronic phencyclidine (PCP), memory and auditory perception impairments are linked to disrupted connectivity between the medial prefrontal cortex and the dorsal hippocampus. Short-term memory relies on high gamma connectivity from the prefrontal cortex to the hippocampus, while long-term memory retrieval depends on theta connectivity from the hippocampus to the prefrontal cortex. Subchronic PCP impairs both short-term and long-term memory, increases prefrontal activity, decreases hippocampal activity, and disrupts this connectivity. Two weeks of daily risperidone rescues memory deficits, attenuates hippocampal desynchronization, and also ameliorates auditory perception impairments and their neural correlates.
bioRxiv
July 27, 2022
preprint
A network analysis of the human structural connectome that includes the brainstem reveals a more complete picture of the brain's wiring, offering a new perspective on how consciousness may arise from the integrated activity of cortical and subcortical networks.
bioRxiv
July 22, 2022
Salma Salhi, Youssef Kora, Gisu Ham et al.
A computational graph-theoretic analysis of the human structural connectome, incorporating subcortical structures including the brainstem, finds that the brainstem ranks highest across degree, eigenvector, and betweenness centrality metrics. The averaged connectome was derived from 100 healthy adult subjects using Python DIPY and Nibabel libraries. The results indicate the importance of including the brainstem in structural network analyses and suggest that such network-based methods can inform theories of consciousness, including global workspace theory, integrated information theory, and the thalamocortical loop theory.
bioRxiv
October 12, 2021
Sophie Waldron, Rachel Pass, Simonas Griesius et al.
Genetic evidence links disruptions in the DLG2 gene to increased risk for schizophrenia, autism, and intellectual disability. To explore psychiatric traits associated with reduced DLG2 function, a rat model with one functional copy of the Dlg2 gene (Dlg2+/-) was tested for anxiety, sensorimotor gating, reward responses, social behavior, and movement after phencyclidine administration. The rats showed reduced PSD-93 mRNA and protein without compensation from related genes. They exhibited an exaggerated locomotor response to phencyclidine, a hallmark of psychosis models, but no deficits in other behaviors. These findings suggest that DLG2 haploinsufficiency produces subtle, psychosis-related effects, unlike the more severe impairments seen in models with complete gene loss.
bioRxiv
August 31, 2021
O. Alitalo, S. Kohtala, Marko Rosenholm et al.
preprint
Both pharmacological and non-pharmacological treatments for depression activate TrkB receptors—a known antidepressant target—by inducing a physiological response linked to sedation. Rapid-acting antidepressants trigger TrkB signaling by evoking a state characterized by electroencephalographic slow-wave activity, behavioral immobility, reduced cerebral glucose utilization, and lowered body temperature. This signaling was not impaired in animals with reduced activity-dependent BDNF release but was diminished by maintaining animals in a warm ambient temperature. Preventing the hypothermic response attenuated the behavioral effects of the rapid-acting antidepressant nitrous oxide. The findings suggest that changes in energy expenditure and thermoregulation are essential, but not sufficient, for antidepressant responses, challenging pharmacology-centric hypotheses and highlighting the role of bioenergetics and thermoregulation.
bioRxiv
July 14, 2021
Jian Li, W. Curley, B. Guérin et al.
preprint
The default mode network (DMN) supports self-awareness and introspection, key to consciousness. Using 7 Tesla resting-state functional MRI data from 168 healthy volunteers and a novel NASCAR tensor decomposition method, researchers mapped DMN subcortical connectivity. They found that signals in the central lateral thalamus and ventral tegmental area strongly correlate with the DMN, with additional sites in the median and dorsal raphe, lateral hypothalamus, and caudate nuclei. The putamen and globus pallidus are anti-correlated with the DMN, supporting the mesocircuit hypothesis of consciousness. This map can guide therapeutic neuromodulation targets for patients with disorders of consciousness.
bioRxiv
May 21, 2021
K. Kishida, L. P. Sands
preprint
Conscious subjective experience is private and dynamic, posing a challenge that neuroscience often sidesteps by focusing on information processing and behavior rather than the 'hard problem' of how neural activity produces phenomenal experience. Computational methods combined with brain-measurement tools are beginning to link dynamic changes in subjective affect with reproducible neurobehavioral signals. Research applying reinforcement learning theory has revealed connections between dopaminergic signals and changes in subjective affect, though dopamine alone cannot explain all affective dynamics. The authors review foundational work, highlight open questions, and propose a Dynamic Affective Core Hypothesis integrating how conscious experiences represent content and context with how they acquire affective subjective value.
bioRxiv
February 12, 2021
S. Trova, Yukie Tsuji, Haruka Horiuchi et al.
preprint
Six days of focused-attention meditation training in novices reduces functional connectivity within the default mode network (DMN), specifically between the ventromedial prefrontal cortex and the posterior cingulate cortex in theta and alpha bands, as measured by electroencephalography. This change correlates with increased state-level mindfulness scores. The findings indicate that even brief meditation practice can modify DMN activity in beginners.
bioRxiv
September 23, 2020
Pengmin Qin, Xuehai Wu, Changwei W Wu et al.
preprint
Local brain regions may support consciousness by acting as hubs within the brain's global network. Using resting-state fMRI data from people in various conscious states—NREM-sleep, REM-sleep, anesthesia, and brain injury patients—and a graph-theoretical measure for detecting local hubs, the authors identify higher-order sensory and motor regions whose degree centrality is significantly reduced during unconsciousness. These regions form a sensorimotor circuit that correlates with levels of consciousness. The findings suggest that integration of higher-order sensorimotor function may be a key mechanism of consciousness, opening novel perspectives for therapeutic modulation of unconsciousness.
bioRxiv
July 9, 2020
Josipa Alilovic, H. Slagter, S. van Gaal
preprint
Valid predictions improve conscious perception of a second target in an attentional blink task, but only when the predictive first target is consciously seen. Unseen first targets do not produce this benefit, regardless of the time interval between targets. The findings clarify how predictive processing and conscious access interact.
bioRxiv
November 2, 2019
R. Limongi, P. Jeon, M. Mackinley et al.
preprint
Psychosis may arise from disrupted brain connectivity caused by insufficient NMDA receptor activity. In a study of 20 people with first-episode psychosis and 20 healthy controls, glutamate levels in the dorsal anterior cingulate cortex (dACC) were linked to altered inhibitory connections within the salience network. Specifically, higher glutamate correlated with weaker inhibitory influence on excitatory neurons in the dACC among those with psychosis. Abnormalities in cognitive-control task performance were tied to these disrupted connections, and the strength of connections from the dACC to the anterior insula was inversely related to social withdrawal severity. The findings suggest that glutamate-driven disinhibition contributes to connectivity deficits and cognitive impairments in psychosis.
bioRxiv
June 29, 2018
Kaili-Larissa Martin, Farah Jindani, N. Turner et al.
preprint
Mindfulness meditation has been used effectively for over five years to treat problem gambling, but the neural mechanisms behind the improvements were unknown. Using resting-state electroencephalography, researchers measured changes in alpha oscillations before and after an eight-week mindfulness meditation intervention and a pre/post five-minute mindfulness meditation body scan in people with problem gambling. After the eight-week intervention, alpha power increased and alpha peak frequency decreased, while the opposite occurred after the brief body scan. The largest alpha rhythm changes were in the frontal and temporal lobes, areas involved in reward and sensory processing. These changes may reflect improved attentional control.