Low and high frequency intracranial neural signals match in the human associative cortex

In vivo intracranial recordings of neural activity offer a unique opportunity to understand human brain function. Intracranial electrophysiological (iEEG) activity related to sensory, cognitive or motor events manifests mostly in two types of signals: event-related local field potentials in lower frequency bands (<30 Hz, LF) and broadband activity in the higher end of the frequency spectrum (>30 Hz, High frequency, HF). While most current studies rely exclusively on HF, thought to be more focal and closely related to spiking activity, the relationship between HF and LF signals is unclear, especially in human associative cortex. Here we provide a large-scale in-depth investigation of the spatial and functional relationship between these 2 signals based on intracranial recordings from 121 individual brains (8000 recording sites). We measure selective responses to complex ecologically salient visual stimuli – human faces - across a wide cortical territory in the ventral occipito-temporal cortex (VOTC), with a frequency-tagging method providing high signal-to-noise ratio (SNR) and the same objective quantification of signal and noise for the two frequency ranges. While LF face-selective activity has higher SNR across the VOTC, leading to a larger number of significant electrode contacts especially in the anterior temporal lobe, LF and HF display highly similar spatial, functional, and timing properties. Specifically, and contrary to a widespread assumption, our results point to nearly identical spatial distribution and local spatial extent of LF and HF activity at equal SNR. These observations go a long way towards clarifying the relationship between the two main iEEG signals and reestablish the informative value of LF iEEG to understand human brain function.

Parallel processing by distinct classes of principal neurons in the olfactory cortex

Understanding how distinct neuron types in a neural circuit process and propagate information is essential for understanding what the circuit does and how it does it. The olfactory (piriform, PCx) cortex contains two main types of principal neurons, semilunar (SL) and superficial pyramidal (PYR) cells. SLs and PYRs have distinct morphologies, local connectivity, biophysical properties, and downstream projection targets. Odor processing in PCx is thought to occur in two sequential stages. First, SLs receive and integrate olfactory bulb input and then PYRs receive, transform, and transmit SL input. To test this model, we recorded from populations of optogenetically identified SLs and PYRs in awake, head-fixed mice. Notably, silencing SLs did not alter PYR odor responses, and SLs and PYRs exhibited differences in odor tuning properties and response discriminability that were consistent with their distinct embeddings within a sensory-associative cortex. Our results therefore suggest that SLs and PYRs form parallel channels for differentially processing odor information in and through PCx.

Segregation, connectivity, and gradients of deactivation in neural correlates of evidence in social decision making

Functional imaging studies of sensory decision making have detected a signal associated with evidence for decisions that is consistent with data from single-cell recordings in laboratory animals. However, the generality of this finding and its implications on our understanding of the organization of the fMRI signal are not clear. In the present functional imaging study, we investigated decisions in an elementary social cognition domain to identify the neural correlates of evidence, their segregation, connectivity, and their relationship to task deactivations. Besides providing data in support of an evidence-related signal in a social cognition task, we were interested in embedding these neural correlates in models of supramodal associative cortex placed at the top of a hierarchy of processing areas. Participants were asked to decide which of two depicted individuals was saddest based on information rich in sensory features (facial expressions) or through contextual cues suggesting the mental state of others (stylized drawings of mourning individuals). The signal associated with evidence for the decision was located in two distinct networks differentially recruited depending on the information type. Using the largest peaks of the signal associated with evidence as seeds in a database of connectivity data, these two networks were retrieved. Furthermore, the hubs of these networks were located near or along a ribbon of cortex located between task activations and deactivations between areas affected by perceptual priming and the deactivated areas of the default network system. In associative cortex, these findings suggest gradients of progressive relative deactivation as a possible neural correlate of the cortical organization envisaged by structural models of cortical organization and by predictive coding theories of cortical function.

The role of m1-cholinergic receptors in associative cortex of young rats in the performing autonomous regulation of heart rate during hypoxic exposure

<p>It is known that human cholinergic transmission in the cerebral cortex required for cognitive and behavioral reactions. However, in the literature there is not enough experimental data on the role of m1‑cholinergic receptors<br />in associative cortex in young rats with incubation in hypoxic environment under conditions of low atmospheric pressure, considering the functional asymmetry of the cerebral hemispheres. The aim of the experiment was to determine the functional consequences of blocking m1‑cholinergic receptors in the associative cortex in young rats with incubation in hypoxic environment under conditions of low atmospheric pressure. Functional consequences of blocking m1‑cholinergic receptors in the associative cortex in young rats with incubation in hypoxic environment under conditions of low atmospheric pressure are different in the case of right-sided and left-sided application of pirenzepin.</p>

ЗАСТОСУВАННЯ ІНФОРМАЦІЙНИХ ТЕХНОЛОГІЙ ДЛЯ ОЦІНКИ ОСОБЛИВОСТЕЙ РЕАКТИВНОСТІ ОРГАНІЗМУ МОЛОДИХ ЩУРІВ ПРИ ЕКСПЕРИМЕНТАЛЬНІЙ ГІПОКСІЇ

<p>Research of adaptation mechanisms in young body to factors such as hypoxic effect is an actual scientific problem. The aim of the experiment was to determine the functional consequences of changes in ion permeability of cell membranes in the associative cortex in young rats ufter incubation at hypoxic environment under conditions of low atmospheric pressure.<br />Incubation of rats in the hypoxic environment under conditions of moderately low atmospheric pressure leads to increased permeability of cell membranes for Na + and Cl- ions at the associative cortex. This is a functional feature of hypoxic damage to membrane structures of nerve tissue that causes compensatory limit the activity of the central contour regulation of heart rate and decrease activity of the sympathetic regulation. Peculiarities in reactivity of young rats exist due to the immaturity of fronto-thalamic brain system.</p>

Autonomous regulation of heart rate in conditions of blocking the beta 1-adrenergic receptors in associative cortex of young rats with hypoxic exposure

<p>The literature discusses modulation of beta-adrenergic receptors sensitivity of the cerebral cortex under changed<br />conditions for the functioning of the body. However, very little data on the effect of the hypoxic environment to the<br />sensitivity of beta-adrenergic receptors of the cerebral cortex in a young body, which possible to investigate in<br />experiments on rats. The aim of the experiment was to determine the functional consequences of the exclusion of<br />beta1-adrenergic receptors in the associative cortex in young rats after incubation in hypoxic environment under<br />conditions of low atmospheric pressure. Blocking the beta1-adrenergic receptors in young rat’s associative cortex<br />can significantly offset the regulatory effects on heart rate that occurred during incubation in the hypoxic environment<br />under conditions of low atmospheric pressure. Hypoxic effect in young rats resulted in a significant decrease in<br />sensitivity beta1-adrenergic receptors in the associative cortex.</p>

Differences in electric activity of women brain upon testing of simple sensomotor reactions during ovulation and lutein phases

As a result of researches of 10 women 20±2 years in 2 phases of a menstrual cycle it was revealed, that in functional trial "Simple sensomotor reaction" in comparison with functional trial "The open eyes" during the ovulation phase took place the activation of the fronto – parietal systems and the formation of the system top – down control over influence of the increased level of testosterone. While in the lutein phase under the influence of the increased level of a cortisol the formation of the right – hemisphere neural network with attraction of the associative cortex in the context of which the simple sensomotor reaction was realized was observed.