Topic: local field potentials

Gaute Einevoll explains how biophysical models connect neural activity to extracellular measurements such as spikes, local field potentials and EEG.

This webinar will showcase new approaches for electrophysiological recordings using our silicon neural probes and surface arrays combined with diverse optical methods such as wide-field or 2-photon imaging, fiber photometry, and optogenetic perturbations in awake, behaving mice. Multi-modal recording of single units and local field potentials across cortex, hippocampus and thalamus alongside calcium activity via GCaMP6F in cortical neurons in triple-transgenic animals or in hippocampal astrocytes via viral transduction are brought to bear to reveal hitherto inaccessible and under-appreciated a

In understanding circuit operations, a key issue is the extent to which neuronal spiking reflects local computation or responses to upstream inputs. Because pyramidal cells in CA1 do not have local recurrent projections, it is currently assumed that firing in CA1 is inherited from its inputs – thus, entorhinal inputs provide communication with the rest of the neocortex and the outside world, whereas CA3 inputs provide internal and past memory representations. Several studies have attempted to prove this hypothesis, by lesioning or silencing either area CA3 or the entorhinal cortex and examinin

The interaction between spontaneously and externally evoked neuronal activity is fundamental for a functional brain. Increasing evidence suggests that bursts of high-power oscillations in the 15-30 Hz beta-band represent activation of resting state networks and can mask perception of external cues. Yet demonstration of the effect of beta power modulation on perception in real-time is missing, and little is known about the underlying mechanism. In this talk I will present the methods we developed to fill this gap together with our recent results. We used a closed-loop stimulus-intensity adjustm

Starting with the work of Hodgkin and Huxley in the 1950s, we now have a fairly good understanding of how the spiking activity of neurons can be modelled mathematically. For cortical circuits the understanding is much more limited. Most network studies have considered stylized models with a single or a handful of neuronal populations consisting of identical neurons with statistically identical connection properties. However, real cortical networks have heterogeneous neural populations and much more structured synaptic connections. Unlike typical simplified cortical network models, real network

Coherent oscillations of neuronal activity are ubiquitous across brain spatial and temporal scales. Gamma oscillations (30-120Hz), detectable with Local Field Potentials (LFPs), are classically analyzed through massive trial averages. This approach leaves us with one average oscillation shape, one mean power and a view based on rigid frequency bands. Consistently, mechanisms based on biophysical models of neural networks typically predict periodic oscillations (e.g. PING models [1]). The functional role of oscillations have been largely investigated in the hippocampus, where, different gamma-f

In visual scenes, the presence of corner elements greatly simplifies object recognition [1]. It has been suggested that cortical area V4 is responsible for the processing of these elements, since neurons exhibit selectivity for different curvatures [2]. However, V4 response properties and their contribution to contour integration or shape completion are still far from being understood. We investigated visually-evoked responses of macaque V4 neurons to sparse random stimuli, composed of angled segments pointing in two directions like clock hands (Fig 1a). Recordings were obtained using a 96-cha

The ability to withhold a response and appropriately time one’s actions is an essential component of goal-directed behavior. Aspects of such cognitive control in rodents are supported by the medial prefrontal cortex (mPFC). The mPFC and its subareas are a site of distinct delay-related activity during motor preparation. However, how mPFC integrates relevant information and exercises the control over behavioral responses remains incompletely understood. Here we characterized local field potentials (LFPs) within mPFC with a focus on the detection of beta bursts – discrete oscillatory events in t

Flexible routing of visual input signals has been linked to changing patterns of synchrony between gamma rhythms of distant neural groups. It has been proposed that attention increases distant gamma-band synchrony by increasing the gamma frequency of the sender group processing the attended stimulus. This stimulus is subsequently preferentially processed. However, the frequency of gamma activity fluctuates over time, varies between areas, and depends on stimulus characteristics, which may complicate entrainment between oscillators. Here, we investigate the relationship between the frequency of

The reciprocal connectivity of the nucleus reuniens (RE) of the ventral midline thalamus with the prefrontal cortex (PFC) and hippocampus (HC) is suggestive of the RE being a critical node within a large-scale brain network underlying spatial cognition. The RE activity has been implicated in navigation, decision making, and spatial memory consolidation. We have previously shown that the RE activity is critical for the retrieval of spatial memory. Yet, the network mechanisms of the RE contribution to the extended prefrontal-thalamo-hippocampal circuit remain to be explored. It has been suggeste