Challenges and opportunities of advancing fMRI resolution, interpretability, and utility

by prof. Peter Bandettini, National Institute of Health, USA

When: September 29th, 2022 – 3:00 pm

Where: Zoom meeting. Recording available on Mediaspace

Abstract: Functional MRI has been advanced by improvements in acquisition, processing, and our understanding of the neurovascular response, leading to new insights, applications, and avenues of research. In this lecture, the challenges and opportunities in working with fMRI at its limits of resolution,
sensitivity, and interpretability are described. Several examples of ultra-high resolution mapping of cortical layer activity and connectivity are shown, opening up the capability of fMRI to map directional connectivity and functional hierarchy. Also presented are some of my lab’s recent work on tracking ongoing cognition, assessing vigilance, and reducing physiologic noise – all through the integration of novel pulse sequences, paradigms, and processing methods.

A novel electrocortical approach for the identification of dysfunctional emotional processing in dysphoria

Reduced approach motivation, indexed by reduced emotional responding to pleasant stimuli, and increased cognitive elaboration of unpleasant stimuli, are increasingly considered putative risk factors for depression. A novel approach to simultaneously examine these two processes is to examine time-frequency delta and theta power while participants are exposed to emotional pictures. Indeed, delta power appears to have a functional role in monitoring the motivational relevance of affective cues and in the identification of pleasant/rewarding stimuli and is generated by subcortical regions involved in the motivational system. Whereas theta power reflects the processing of salient events and can be employed to assess cognitive processing during the viewing of affective content.

Physics and Neuroscience: complex models of injured brains predict neurological deficits

The study ‘Recovery of neural dynamics criticality in personalized whole brain models of stroke‘ published in Nature Communications, fruit of an international collaboration among physicists, neurologists, psychologists, and PNC members Samir Suweis, Marco Zorzi and Maurizio Corbetta, proposes the theory of brain criticality to explain brain-behavior relationships in neurological patients.

Criticality is a physical state at the transition between order and disorder, and previous studies had shown that healthy brains work at criticality.

This study shows that patients affected by stroke present at three months decreased levels of neural activity, decreased entropy, and decreased strength of functional connections.

Proff. Annachiara Cagnin, Diego Cecchin and colleagues published a paper about brain amyloid PET analysis

To date, there is no consensus on how to semi-quantitatively assess brain amyloid PET.

Researchers used data from 85 patients who underwent dual time-point PET/MRI acquisitions. The correlations with a gold standard (SI) were computed and the methods compared with the visual assessment.

Each quantifier exhibited excellent agreement with visual assessment and strong correlation with SI (average AUC = 0.99, ρ = 0.91). Among the other methods, TDr came closest to the reference with less implementation complexity.

The ability of techniques integrating blood perfusion to depict age-related variations in amyloid load in amyloid-negative subjects demonstrates the goodness of the estimate.

New paper by Prof. Bisazza and colleagues about the cognitive abilities of newly hatched zebrafish

What are the cognitive abilities of a newly hatched zebrafish? A research from the University of Padova found that hatchings are able to associate a visual stimulus with presence of food. Learning occurs much faster in larvae than in adult zebrafish, requiring less than 48h to establish an association.

This feature was exploited to assess the capacity of larval zebrafish to recognize objects. Larvae can easily discriminate two objects by their color or shape. They can also perceive more complex visual properties, being able to discriminate two identical objects with a different spatial orientation or an object from its mirror image.

‘Little brain’, big contributions – Reflection on cerebellar circuitry in action, perception, and cognition

by prof. Sonja Kotz – University of Maastricht

When: July 7th, 2022 – 3:00 pm

Where: Sala Seminari, VIMM. Recording available on Mediaspace

Abstract: It is well established that cortico-cerebellar-cortical circuitry monitors motor behavior, but recent evidence established that this circuitry similarly engages in the temporal encoding of basic and more complex (multi)sensory information. Consequently, cerebellar computations may generally apply to the temporal encoding of motor and basic and complex (multi)sensory information as (i) such information stimulates and monitors cortical information processing, and (ii) cerebellar-thalamic output might be a possible source of endogenous activity, predicting the outcome of cortical information processing and (iii) possibly providing a temporal frame for the binding of information.

Thalamic regulation of prefrontal dynamics for cognitive control

by prof. Michael Halassa – MIT, Boston

When: June 23th, 2022 – 3:00 pm

Where: Sala Seminari, VIMM. Recording available on Mediaspace

Abstract: Interactions between the thalamus and cortex are critical for normal cognition. Although classical theories emphasize its role in transmitting signals to or between cortical areas, recent studies show that the thalamus modulates cortical function through additional mechanisms. In this talk, I will discuss findings that highlight the role of the mediodorsal (MD) thalamus in regulating prefrontal excitatory/inhibitory balance and effective connectivity during decision making. I will present recently published data showing that the MD thalamus dynamically adjusts prefrontal evidence integration according to incoming stimulus statistics.

From synapse to network: models of information storage and retrieval in brain networks

by prof. Nicolas Brunel, Duke University

When: June 16th, 2022 – 3:00 pm

Where: VIMM Meeting room – Recording available on Mediaspace

Abstract: Brains have a remarkable ability to store information about the external world, on time scales that range from seconds to the lifetime of an animal. What are the mechanisms by which information is stored in the brain, and how is stored information retrieved from memory? One of the central hypothesis of neuroscience is that information is stored through synaptic plasticity – modifications of synaptic connectivity between neurons. Theoretical models have explored the impact of such synaptic plasticity mechanisms on network dynamics.

Deciphering how cortical astrocytes dynamically regulate synaptic plasticity ensuring the information storage in memory circuits

by prof. Marco Canossa, CIBIO, University of Trento

When: June 9th, 3:00 PM

Where: Aula 0B, Complesso di Biomedicina, Fiore di Botta, Padova

Abstract: In the cerebral cortex neurons are organized in specific layers and form connections both within the cortex and with other brain regions, thus forming a network of synaptic connections comprising distinct circuits. Plasticity is a fundamental feature of neuronal connections in the brain, where experience-dependent changes in synaptic strengths are crucial for creating learning and memory circuits (engrams). Deciphering how neurons dynamically express synaptic plasticity while ensuring the formation of memory circuits remains a key challenge. Glial cells respond to neuronal activation and release neuroactive molecules (termed “gliotransmitters”) that can affect synaptic activity and modulate plasticity.

A diurnal rhythm of intracellular chloride in pyramidal neurons affects cortical dynamics and signal processing in the cortex

by prof. Gian Michele Ratto, Consiglio Nazionale delle Ricerche, Pisa

When: May 26th, 2022 – 3:00 pm

Where: Sala Seminari at VIMM. Recording available on Mediaspace

Abstract: Living organisms navigate through a cyclic world: activity, feeding, social interactions
are all organized along the periodic daily rhythm synchronized by external environmental cues and
brain function varies markedly through the day. An obvious contributory factor is the large change
in the level of sensory drive from day to night. Less obvious is the degree to which intrinsic
neuronal activity might vary, yet there is abundant clinical data supporting the idea that many
functional neurological and psychiatric conditions have strong diurnal patterns.

PNC

Padova Neuroscience Center

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