scholarly journals Gaze-Related Activity in Primate Frontal Cortex Predicts and Mitigates Spatial Uncertainty

2021 ◽  
Author(s):  
Vishal Bharmauria ◽  
Adrian Schuetz ◽  
Parisa Abedi Khoozani ◽  
Xiaogang Yan ◽  
Hongying Wang ◽  
...  
Keyword(s):  
Frontal Cortex ◽  
Spatial Uncertainty ◽  
Primate Behavior ◽  
Related Activity ◽  
Conflict Task ◽  
Circular Distribution ◽  
Remarkable Feature ◽  
Future Events ◽  
Supplementary Eye Fields ◽  
The Brain

A remarkable feature of primate behavior is the ability to predict future events based on past experience and current sensory cues. To understand how the brain plans movements in the presence of unstable cues, we recorded gaze-related activity in the frontal cortex of two monkeys engaged in a quasi-predictable cue-conflict task. Animals were trained to look toward remembered visual targets in the presence of a landmark that shifted with fixed amplitude but randomized direction. As simulated by a probabilistic model based on known physiology/behavior, gaze end points assumed a circular distribution around the target, mirroring the possible directions of the landmark shift. This predictive strategy was reflected in frontal cortex activity (especially supplementary eye fields), which anticipated future gaze distributions before the actual landmark shift. In general, these results implicate prefrontal cortex in the predictive integration of environmental cues and their learned statistical properties to mitigate spatial uncertainty.

scholarly journals Decoding the future from past experience: learning shapes predictions in early visual cortex

2015 ◽  
Vol 113 (9) ◽  
pp. 3159-3171 ◽  
Author(s):  
Caroline D. B. Luft ◽  
Alan Meeson ◽  
Andrew E. Welchman ◽  
Zoe Kourtzi
Keyword(s):  
Visual Cortex ◽  
Large Scale ◽  
Sequence Structure ◽  
Neural Populations ◽  
Early Visual Cortex ◽  
Temporal Structures ◽  
Future Events ◽  
Sensory Predictions ◽  
Actual Stimulus ◽  
The Brain

Learning the structure of the environment is critical for interpreting the current scene and predicting upcoming events. However, the brain mechanisms that support our ability to translate knowledge about scene statistics to sensory predictions remain largely unknown. Here we provide evidence that learning of temporal regularities shapes representations in early visual cortex that relate to our ability to predict sensory events. We tested the participants' ability to predict the orientation of a test stimulus after exposure to sequences of leftward- or rightward-oriented gratings. Using fMRI decoding, we identified brain patterns related to the observers' visual predictions rather than stimulus-driven activity. Decoding of predicted orientations following structured sequences was enhanced after training, while decoding of cued orientations following exposure to random sequences did not change. These predictive representations appear to be driven by the same large-scale neural populations that encode actual stimulus orientation and to be specific to the learned sequence structure. Thus our findings provide evidence that learning temporal structures supports our ability to predict future events by reactivating selective sensory representations as early as in primary visual cortex.

Neural Mechanisms of Negative Symptoms

1989 ◽  
Vol 155 (S7) ◽  
pp. 93-98 ◽  
Author(s):  
Nancy C. Andreasen
Keyword(s):  
Frontal Cortex ◽  
Negative Symptoms ◽  
Neural Mechanism ◽  
Brain Regions ◽  
Brain Dysfunction ◽  
Neural Mechanisms ◽  
Dementia Praecox ◽  
Intellectual Abilities ◽  
The Brain ◽  
Psychic Mechanisms

When Kraepelin originally defined and described dementia praecox, he assumed that it was due to some type of neural mechanism. He hypothesised that abnormalities could occur in a variety of brain regions, including the prefrontal, auditory, and language regions of the cortex. Many members of his department, including Alzheimer and Nissl, were actively involved in the search for the neuropathological lesions that would characterise schizophrenia. Although Kraepelin did not use the term ‘negative symptoms', he describes them comprehensively and states explicitly that he believes the symptoms of schizophrenia can be explained in terms of brain dysfunction:“If it should be confirmed that the disease attacks by preference the frontal areas of the brain, the central convolutions and central lobes, this distribution would in a certain measure agree with our present views about the site of the psychic mechanisms which are principally injured by the disease. On various grounds, it is easy to believe that the frontal cortex, which is specially well developed in man, stands in closer relation to his higher intellectual abilities, and these are the faculties which in our patients invariably suffer profound loss in contrast to memory and acquired ability.” Kraepelin (1919, p. 219)

the Comparred Effect of Zyprasidone and Haloperidol at Hippocampal and Frontal Cortex at Rats

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
D. Marinescu ◽  
L. Mogoanta ◽  
T. Udristoiu
Keyword(s):  
Adverse Event ◽  
Frontal Cortex ◽  
Negative Symptoms ◽  
Structural Changes ◽  
Saline Solution ◽  
Neuroprotective Effect ◽  
Neuronal Loss ◽  
D2 Receptors ◽  
Cerebral Structure ◽  
The Brain

Background:The alteration of hippocampal and prefrontal structures is linked with schizophrenia cognitive impairment and negative symptoms. the antipsychotics can induced apoptotic mechanisms correlated with the psychopharmacological mechanism of excesive blocking of the D2 receptors. Distress determined increase of the glucocorticoid aggression wich drive to the decrease of neuroprotective capacity at the brain level.Methods:We formed 5 study lots (5 adults rats) and a control lot. the substancies were administrated intraperitoneal, daily, saline solution equivalent to: ziprasidone (1.25mg/kg/day) and haloperidole (0.20mg/kg/day), dexametasone (0.20mg/kg/day):N1 - Haloperidole; N2 - Dexametasone; N3 - Ziprasidone; N4 - Dexametasone and Haloperidole; N5 - Dexametasone and Ziprasidone; N6 -control lot.We monitorised the cardiovascular function, respiration and EPS, without signaling any serious deadly adverse event. the rats were sacrificed during the 10th day and 21th day.Results:Frontal cortex and hippocamp were the most intensely affected even since the 10-th day to the N4 (haloperidole and dexametasone) lot with massive neuronal loss at the VI, V, and IV frontal cerebral layers.The lots treated with ziprasidone presented significant lesser structural changes in frontal cortex and hippocamp, comparative to haloperidole. the lots treated with dexametasone and ziprasidone (N5) are lesser affected at the cerebral structure level.Conclusions:Haloperidole has a significant decrease in neuroprotection. Ziprasidone demonstrated an neuroprotective effect.

scholarly journals Human brain harbors single nucleotide somatic variations in functionally relevant genes possibly mediated by oxidative stress

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2520 ◽  
Author(s):  
Anchal Sharma ◽  
Asgar Hussain Ansari ◽  
Renu Kumari ◽  
Rajesh Pandey ◽  
Rakhshinda Rehman ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Corpus Callosum ◽  
Human Brain ◽  
Frontal Cortex ◽  
Oxidative Stress Marker ◽  
Somatic Variation ◽  
Single Nucleotide ◽  
Normal Human Brain ◽  
Normal Human ◽  
The Brain

Somatic variation in DNA can cause cells to deviate from the preordained genomic path in both disease and healthy conditions. Here, using exome sequencing of paired tissue samples, we show that the normal human brain harbors somatic single base variations measuring up to 0.48% of the total variations. Interestingly, about 64% of these somatic variations in the brain are expected to lead to non-synonymous changes, and as much as 87% of these represent G:C>T:A transversion events. Further, the transversion events in the brain were mostly found in the frontal cortex, whereas the corpus callosum from the same individuals harbors the reference genotype. We found a significantly higher amount of 8-OHdG (oxidative stress marker) in the frontal cortex compared to the corpus callosum of the same subjects (p<0.01), correlating with the higher G:C>T:A transversions in the cortex. We found significant enrichment for axon guidance and related pathways for genes harbouring somatic variations. This could represent either a directed selection of genetic variations in these pathways or increased susceptibility of some loci towards oxidative stress. This study highlights that oxidative stress possibly influence single nucleotide somatic variations in normal human brain.

scholarly journals Evaluation of Genotype-Based Gene Expression Model Performance: A Cross-Framework and Cross-Dataset Study

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1531
Author(s):  
Vânia Tavares ◽  
Joana Monteiro ◽  
Evangelos Vassos ◽  
Jonathan Coleman ◽  
Diana Prata
Keyword(s):  
Gene Expression ◽  
Frontal Cortex ◽  
Model Performance ◽  
Variation Method ◽  
Expression Model ◽  
The Brain ◽  
Gene Expression Model ◽  
And Training ◽  
Predict Gene Expression ◽  
Fold Cross Validation

Predicting gene expression from genotyped data is valuable for studying inaccessible tissues such as the brain. Herein we present eGenScore, a polygenic/poly-variation method, and compare it with PrediXcan, a method based on regularized linear regression using elastic nets. While both methods have the same purpose of predicting gene expression based on genotype, they carry important methodological differences. We compared the performance of expression quantitative trait loci (eQTL) models to predict gene expression in the frontal cortex, comparing across these frameworks (eGenScore vs. PrediXcan) and training datasets (BrainEAC, which is brain-specific, vs. GTEx, which has data across multiple tissues). In addition to internal five-fold cross-validation, we externally validated the gene expression models using the CommonMind Consortium database. Our results showed that (1) PrediXcan outperforms eGenScore regardless of the training database used; and (2) when using PrediXcan, the performance of the eQTL models in frontal cortex is higher when trained with GTEx than with BrainEAC.

scholarly journals Sleeping While Awake: The Intrusion of Neural Activity Associated with Sleep Onset in the Awake Human Brain

2020 ◽  
Author(s):  
Stephanie Hawes ◽  
Carrie R. H. Innes ◽  
Nicholas Parsons ◽  
Sean P.A. Drummond ◽  
Karen Caeyensberghs ◽  
...  
Keyword(s):  
Human Brain ◽  
Basal Forebrain ◽  
Brain Activity ◽  
Cognitive Task ◽  
Sleep Onset ◽  
Theoretical Modelling ◽  
Related Activity ◽  
Independent Dataset ◽  
Time Graph ◽  
The Brain

AbstractSleep can intrude into the awake human brain when sleep deprived or fatigued, even while performing cognitive tasks. However, how the brain activity associated with sleep onset can co-exist with the activity associated with cognition in the awake humans remains unexplored. Here, we used simultaneous fMRI and EEG to generate fMRI activity maps associated with EEG theta (4-7 Hz) activity associated with sleep onset. We implemented a method to track these fMRI activity maps in individuals performing a cognitive task after well-rested and sleep-deprived nights. We found frequent intrusions of the fMRI maps associated with sleep-onset in the task-related fMRI data. These sleep events elicited a pattern of transient fMRI activity, which was spatially distinct from the task-related activity in the frontal and parietal areas of the brain. They were concomitant with reduced arousal as indicated by decreased pupil size and increased response time. Graph theoretical modelling showed that the activity associated with sleep onset emerges from the basal forebrain and spreads anterior-posteriorly via the brain’s structural connectome. We replicated the key findings in an independent dataset, which suggests that the approach can be reliably used in understanding the neuro-behavioural consequences of sleep and circadian disturbances in humans.

scholarly journals Reducing future fears by suppressing the brain mechanisms underlying episodic simulation

2016 ◽  
Vol 113 (52) ◽  
pp. E8492-E8501 ◽  
Author(s):  
Roland G. Benoit ◽  
Daniel J. Davies ◽  
Michael C. Anderson
Keyword(s):  
Prefrontal Cortex ◽  
Dorsolateral Prefrontal Cortex ◽  
Ventromedial Prefrontal Cortex ◽  
Episodic Simulation ◽  
Dorsolateral Prefrontal ◽  
Future Events ◽  
The Right ◽  
Development Of Anxiety ◽  
The Brain

Imagining future events conveys adaptive benefits, yet recurrent simulations of feared situations may help to maintain anxiety. In two studies, we tested the hypothesis that people can attenuate future fears by suppressing anticipatory simulations of dreaded events. Participants repeatedly imagined upsetting episodes that they feared might happen to them and suppressed imaginings of other such events. Suppressing imagination engaged the right dorsolateral prefrontal cortex, which modulated activation in the hippocampus and in the ventromedial prefrontal cortex (vmPFC). Consistent with the role of the vmPFC in providing access to details that are typical for an event, stronger inhibition of this region was associated with greater forgetting of such details. Suppression further hindered participants’ ability to later freely envision suppressed episodes. Critically, it also reduced feelings of apprehensiveness about the feared scenario, and individuals who were particularly successful at down-regulating fears were also less trait-anxious. Attenuating apprehensiveness by suppressing simulations of feared events may thus be an effective coping strategy, suggesting that a deficiency in this mechanism could contribute to the development of anxiety.

Genesis of rhythmic respiratory activity in pons independent of medulla

1985 ◽  
Vol 59 (3) ◽  
pp. 684-690 ◽  
Author(s):  
W. M. St John ◽  
T. A. Bledsoe
Keyword(s):  
Brain Stem ◽  
Phrenic Nerve ◽  
Respiratory Activity ◽  
Respiratory Rhythm ◽  
Related Activity ◽  
Pharmacological Agents ◽  
Pneumotaxic Center ◽  
Trigeminal Nerves ◽  
The Brain ◽  
Pontomedullary Junction

We hypothesized that rhythmic respiratory-related activity could be generated in pons independent of medullary mechanisms. In decerebrate, cerebellectomized, vagotomized, paralyzed, and ventilated cats, we recorded efferent activities of the phrenic nerve and mylohyoid branch of the trigeminal nerve. Following transections of the brain stem at the pontomedullary junction, the phrenic and trigeminal nerves discharged with independent rhythms. Spontaneous trigeminal discharges eventually ceased but were reestablished after strychnine, doxapram, and/or protriptyline were administered. In some animals having no spontaneous trigeminal discharges after transection, these discharges appeared, with a rhythm different from the phrenic, following administration of these agents. In other cats having no transections between pons and medulla, these pharmacological agents induced trigeminal and phrenic discharges after kainic acid had been injected into the entire dorsal and ventral medullary respiratory nuclei. Phrenic and trigeminal discharges were linked, indicating survival of bulbospinal neurons or presence of pontospinal units. We conclude that rhythms, similar to respiratory rhythm, can occur by mechanisms in isolated pons. Such mechanisms are hypothesized to be within the pneumotaxic center and may underlie the neurogenesis of eupnea.

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