Michal Zochowski

• PhD
• Professor (Full) at University of Michigan

The human brain is a complex system whose temporally and spatially multiscale structure gives rise to an immense functionality, which can coexist with pathophysiologic functioning in case of diseased states. Many important advances in various fields of research critically continue to improve our understanding of the structure and (dys-)function of...

Neuromodulatory processes in the brain can critically change signal processing on a cellular level leading to dramatic changes in network level reorganization. Here, we use coupled non-identical Kuramoto oscillators to investigate how changes in the shape of phase response curves from Type 1 to Type 2, mediated by varying ACh levels, coupled with a...

High frequency oscillations are a promising biomarker of outcome in intractable epilepsy. Prior high frequency oscillation work focused on counting high frequency oscillations on individual channels, and it is still unclear how to translate those results into clinical care. We show that high frequency oscillations arise as network discharges that h...

Forebrain acetylcholine (ACh) signaling has been shown to drive attention and learning. Recent experimental evidence of spatially and temporally constrained cholinergic signaling has sparked interest to investigate how it facilitates stimulus-induced learning. We use biophysical excitatory-inhibitory (E-I) multi-module neural network models to show...

Across vertebrate species, sleep consists of repeating cycles of NREM followed by REM. However, the respective functions of NREM, REM, and their stereotypic cycling pattern are not well understood. Using a simplified biophysical network model, we show that NREM and REM sleep can play differential and critical roles in memory consolidation primarily...

Rhythmic synchronization of neuronal firing patterns is a widely present phenomenon in the brain—one that seems to be essential for many cognitive processes. A variety of mechanisms contribute to generation and synchronization of network oscillations, ranging from intrinsic cellular excitability to network mediated effects. However, it is unclear h...

General anesthetics work through a variety of molecular mechanisms while resulting in the common end point of sedation and loss of consciousness. Generally, the administration of common anesthetics induces reduction in synaptic excitation while promoting synaptic inhibition. Exogenous modulation of the anesthetics’ synaptic effects can help determi...

Hidden hearing loss (HHL) is a deficit in auditory perception and speech intelligibility that occurs despite normal audiometric thresholds and results from noise exposure, aging, or myelin defects. While mechanisms causing perceptual deficits in HHL patients are still unknown, results from animal models indicate a role for peripheral auditory neuro...

General anesthetics work through a variety of molecular mechanisms while resulting in the common end point of sedation and loss of consciousness. Generally, the administration of common inhalation anesthetics induces decreases in synaptic excitation while promoting synaptic inhibition. Animal studies have shown that, during anesthesia, exogenously...

Sleep is indispensable for most animals’ cognitive functions, and is hypothesized to be a major factor in memory consolidation. Although we do not fully understand the mechanisms of network reorganisation driving memory consolidation, available data suggests that sleep-associated neurochemical changes may be important for such processes. In particu...

Sleep is critical for memory consolidation, although the exact mechanisms mediating this process are unknown. Combining reduced network models and analysis of in vivo recordings, we tested the hypothesis that neuromodulatory changes in acetylcholine (ACh) levels during non-rapid eye movement (NREM) sleep mediate stabilization of network-wide firing...

Theta and gamma rhythms and their cross-frequency coupling play critical roles in perception, attention, learning, and memory. Available data suggest that forebrain acetylcholine (ACh) signaling promotes theta-gamma coupling, although the mechanism has not been identified. Recent evidence suggests that cholinergic signaling is both temporally and s...

[This corrects the article DOI: 10.1371/journal.pcbi.1008499.].

Hidden hearing loss (HHL) is an auditory neuropathy characterized by normal hearing thresholds but reduced amplitudes of the sound-evoked auditory nerve compound action potential (CAP). In animal models, HHL can be caused by moderate noise exposure or aging, which induces loss of inner hair cell (IHC) synapses. In contrast, recent evidence has show...

Hidden hearing loss (HHL) is an auditory neuropathy characterized by normal hearing thresholds but reduced amplitude of the sound-evoked auditory nerve compound action potential (CAP). It has been proposed that in humans HHL leads to speech discrimination and intelligibility deficits, particularly in noisy environments. Animal models originally ind...

Acetylcholine (ACh), one of the brain’s most potent neuromodulators, can affect intrinsic neuron properties through blockade of an M-type potassium current. The effect of ACh on excitatory and inhibitory cells with this potassium channel modulates their membrane excitability, which in turn affects their tendency to synchronize in networks. Here, we...

Sleep plays a critical role in memory consolidation, although the exact mechanisms mediating this process are unknown. Combining computational and in vivo experimental approaches, we test the hypothesis that reduced cholinergic input to the hippocampus during non-rapid eye movement (NREM) sleep generates stable spike timing relationships between ne...

Recent experimental results have shown that the detection of cues in behavioral attention tasks relies on transient increases of acetylcholine (ACh) release in frontal cortex and cholinergically‐driven oscillatory activity in the gamma frequency band(Howe et al., 2017).The cue‐induced gamma rhythmic activity requires stimulation of M1 muscarinic re...

The relation between mental and behavior process has provided an enduring focus in psychology since the field’s genesis, with an impressive number of theories advanced to explain and predict this relationship. To a large extent, these theories part ways in the primacy they attach to the operation of mind versus the conduct of action. Some emphasize...

Social Entrepreneurs (SE) solve pressing and insurmountable social problems, making an immense, yet durable and irreversible social impact. They do these remarkable things with minimal investments, having as assets their passion, commitment, big yet realistic visons for change, creativity, and entrepreneurial skills.

The emergence of conscious experience from distributed neural activity is possibly the most dramatic example of how coordination of elements leads to function. We can depict mental processing as a continuous process of organizing items into functional units. If we accept the assumption that the brain is the source of cognition, consciousness and th...

Social interaction and social relations have each provided a central focus in social psychology since the field’s inception. Social interaction can take many forms, from parallel play to coordinated action and from nonverbal displays to the exchange of abstract ideas in words. Social relations, too, vary along several dimensions, including antagoni...

The traditional psychotherapeutic approaches (i.e., psychoanalytic or neo-behavioral) focus on individuals who develop specific symptoms. We present here a different approach, based on the Family System Theory, which considers the process of synchronization and the way synchronizing elements generate dysfunctional or functional units.

Human behavior can take very diverse forms. In the course of a few hours, you may be preparing breakfast, having an empathic conversation with your partner, dealing with an obnoxious salesperson on the phone, working on a scientific manuscript, engaging in a group discussion with colleagues, and replacing a flickering light in a conference room. Ea...

Humans are a social species and spent most of their time interacting with many people and forming relationships with a significantly smaller subset of these people. While the previous chapter focused on dyadic interactions and the formation of dyadic relationships, it is clearly the case that much of social life takes place in the context of more t...

Social change, when neither imposed from the outside nor the result of major upheavals, seems an intriguing phenomenon, especially when it stems from endogenous social processes coordinated in time. It often happens that the activated societal dynamics are temporary and short-lived—bursting forth and, in fairly short order, fading away. These short...

Conscious thoughts are obviously the result of the brain’s functioning. Less obvious is how the ongoing synchronization of multiple neural assemblies gives rise to a single and relatively stable higher-order thought.

Recent work has explored spatio‐temporal relationships between excitatory (E) and inhibitory (I) signaling within neural networks, and the effect of these relationships on network activity patterns. Data from these studies have indicated that excitation and inhibition are maintained at a similar level across long time periods, and that excitatory a...

This book introduces the reader to the concept of functional synchronization and how it operates on very different levels in psychological and social systems – from the emergence of thought to the formation of social relations and the structure of societies. For years, psychologists have investigated phenomena such as self-concept, social judgment,...

Rate coding and phase coding are the two major coding modes seen in the brain. For these two modes, network dynamics must either have a wide distribution of frequencies for rate coding, or a narrow one to achieve stability in phase dynamics for phase coding. Acetylcholine (ACh) is a potent regulator of neural excitability. Acting through the muscar...

We explore the possible role of network dynamics near a critical point in the storage of new information in silico and in vivo, and show that learning and memory may rely on neuronal network features mediated by the vicinity of criticality. Using a mean-field, attractor-based model, we show that new information can be consolidated into attractors t...

The communication of neurons is primarily maintained by synapses, which play a crucial role in the functioning of the nervous system. Therefore, synaptic failure may critically impair information processing in the brain and may underlie many neurodegenerative diseases. A number of studies have suggested that synaptic failure may preferentially targ...

Nodal contribution to network-wide MPC as a function of its degree for incoming networks for different direction ratios and failure recovery time constant T. Higher direction ratios result in a more obvious increase in MPC of hubs for T = 5 ms when there’s more failure. MPCs are averaged over 5 degrees and results are averaged over 5 randomized net...

Nodal contribution to network-wide MPC as a function of its degree for outgoing networks for different connectivities and failure recovery time constant. Higher connectivities result in a bigger increase in MPC for T=0.5 ms with higher failure psyn. MPCs are averaged over 5 degrees and results are averaged over 5 randomized network realizations.

Nodal contribution to network-wide MPC as a function of its degree for incoming networks for different connectivities and failure recovery time constant T. The increase in MPC of hubs with higher failure cannot be observed for lower or higher connectivities for T = 5 ms. MPCs are averaged over 5 degrees and results are averaged over 5 randomized ne...

Network spike frequency (A,C) and mean phase coherence (B,D) for various frequencies of random input Irand, for incoming (A,B) and outgoing (C,D) networks. Results are averaged over 5 randomized network realizations.

Nodal contribution to network-wide MPC as a function of its degree for outgoing networks for different direction ratios and failure recovery time constant T. For T = 0.5 ms, the increase in MPC values of psyn = 1.0 is more pronounced for lower direction ratios. MPCs are averaged over 5 degrees and results are averaged over 5 randomized network real...

Decades of neurobehavioral research has linked sleep-associated rhythms in various brain areas to improvements in cognitive performance. However, it remains unclear what synaptic changes might underlie sleep-dependent declarative memory consolidation and procedural task improvement, and why these same changes appear not to occur across a similar in...

Sleep plays a critical role in memory consolidation, however, the exact role that sleep and its effects on neural network dynamics play in this process is still unclear. Here, we combine computational and experimental approaches to study the dynamical, network-wide underpinnings of hippocampal memory consolidation during sleep. We provide data to s...

Significance Networks of neurons need to reliably encode and replay patterns and sequences of activity. In the brain, sequences of spatially coding neurons are replayed in both the forward and reverse direction in time with respect to their order in recent experience. As of yet there is no network-level or biophysical mechanism known that can produ...

Familial cerebral cavernous malformations type III (fCCM3) is a disease of the cerebrovascular system caused by loss-of-function mutations in ccm3 that result in dilated capillary beds that are susceptible to hemorrhage. Before hemorrhage, fCCM3 lesions are characterized by a hyperpermeable blood-brain barrier (BBB), the key pathologic feature of f...

The granule cells born during adult neurogenesis in the dentate gyrus (DG) are thought to be involved in formation of new memory representations. At the same time, they are implicated in exacerbation of the pathology during epilepsy. Moreover, it has been found that patterns of their integration into DG circuits are significantly different in healt...

The interconnectivity between excitatory and inhibitory neural networks informs mechanisms by which rhythmic bursts of excitatory activity can be produced in the brain. One such mechanism, Pyramidal Interneuron Network Gamma (PING), relies primarily upon reciprocal connectivity between the excitatory and inhibitory networks, while also including in...

Background: Recent advances in neurophysiological recording techniques have increased both the spatial and temporal resolution of data. New methodologies are required that can handle large data sets in an efficient manner as well as to make quantifiable, and realistic, predictions about the global modality of the brain from under-sampled recording...

Network oscillations across and within brain areas are critical for learning and performance in memory tasks. While a large amount of work has focused on the generation of neural oscillations, their effects on neuronal populations’ spiking activity and information encoding is less known. Here, we use computational modeling and in vivo recording to...

Significance Previous studies have demonstrated a role of state-specific neural activity in plasticity; however, a mechanism for these changes has yet to be elucidated. Here, we demonstrate that sensory response changes occur in thalamic neurons immediately following novel visual experience, but that subsequent nonrapid eye movement (NREM) oscillat...

This corrects the article DOI: 10.1038/ncomms15039.

Supplementary Figures and Supplementary References

The topical landscape of psychology is highly compartmentalized, with distinct phenomena explained and investigated with recourse to theories and methods that have little in common. Our aim in this article is to identify a basic set of principles that underlie otherwise diverse aspects of human experience at all levels of psychological reality, fro...

Activity in hippocampal area CA1 is essential for consolidating episodic memories, but it is unclear how CA1 activity patterns drive memory formation. We find that in the hours following single-trial contextual fear conditioning (CFC), fast-spiking interneurons (which typically express parvalbumin (PV)) show greater firing coherence with CA1 network...

Supplementary Figures and Supplementary References

The brain forms and stores distributed representations from sparse external input that compete for neuronal resources with already stored memory traces. It is unclear what dynamical properties of neural systems allow formation and subsequent consolidation of new, distributed memory representations under these conditions. Here we use analytical, com...

Astrocytes form interconnected networks in the brain and communicate via calcium signaling. We investigate how modes of coupling between astrocytes influence the spatio-temporal patterns of calcium signaling within astrocyte networks and specifically how these network interactions promote coordination within this group of cells. To investigate thes...

While the interplay between neuronal excitability properties and global properties of network topology is known to affect network propensity for synchronization, it is not clear how detailed characteristics of these properties affect spatiotemporal pattern formation. Here we study mixed networks, composed of neurons having type I and/or type II pha...

The plethora of inhibitory interneurons in the hippocampus and cortex play a pivotal role in generating rhythmic activity by clustering and synchronizing cell firing. Results of our simulations demonstrate that both the intrinsic cellular properties of neurons and the degree of network connectivity affect the characteristics of clustered dynamics e...

Presentation on "25th Annual Computational Neuroscience Meeting: CNS-2016 " BMC Neuroscience 17, 112-113 (2016).

The characteristics of neural network activity depend on intrinsic neural properties and synaptic connectivity in the network. In brain networks, both of these properties are critically affected by the type and levels of neuromodulators present. The expression of many of the most powerful neuromodulators, including acetylcholine (ACh), varies tonic...

The brain can reproduce memories from partial data; this ability is critical for memory recall. The process of memory recall has been studied using auto-associative networks such as the Hopfield model. This kind of model reliably converges to stored patterns which contain the memory. However, it is unclear how the behavior is controlled by the brai...

ICGenealogy: towards a common topology of neuronal ion channel function and genealogy in model and experiment Ion channels are fundamental constituents determining the function of single neurons and neuronal circuits. To understand their complex interactions, the field of computational modeling has proven essential: since its emergence, thousands...

States of arousal, or consciousness with the brain are regulated largely by the neurotransmitter acetylcholine (ACh). Specifically, ACh is likely responsible for the transition between slow wave sleep (SWS; where ACh is absent) and rapid eye movement sleep or waking states (where ACh is high). Patterns of neural activity within the cerebral cortex...

Inhibitory neural networks have the capacity to fire synchronously depending strongly on synaptic current dynamics. Various types of inhibitory interneurons, including some with adaptation currents, are present in hippocampal circuits and are implicated in governing overall network pattern formation. However, the contribution of intrinsic cell firi...

It has been shown that seizures occur more frequently at the transition from wake to sleep, or from one stage of sleep to another. Acetylcholine (ACh) is a neuromo-dulator that controls wake and sleep stages, and is present at high levels during waking and is absent in slow wave sleep (SWS). ACh has also been shown to switch the excitability as mea...

Acetylcholine (ACh) is a regulator of neural excitability and one of the neurochemical substrates of sleep. Amongst the cellular effects induced by cholinergic modulation are a reduction in spike-frequency adaptation (SFA) and a shift in the phase response curve (PRC). We demonstrate in a biophysical model how changes in neural excitability and net...

Heterogeneity in brain networks extends to both intrinsic properties of neurons and the synaptic connections between neurons. Intrinsic neural firing and response properties vary with changing levels of potent neuromodulators that are released throughout the brain by subcortical areas. Synaptic structure can vary by two distinct mechanisms: (1) the...

Understanding spontaneous transitions between dynamical modes in a network is of significant importance. These transitions may separate pathological and normal functions of the brain. In this paper, we develop a set of measures that, based on spatio-temporal features of network activity, predict autonomous network transitions from asynchronous to s...

Understanding the mechanisms underlying distributed pattern formation in brain networks and its content driven dynamical segmentation is an area of intense study. We investigate a theoretical mechanism for selective activation of diverse neural populations that is based on dynamically shifting cellular resonances in functionally or structurally cou...

We study the synchronization of neuronal networks with dynamical heterogeneity, showing that network structures with the same propensity for synchronization (as quantified by master stability function analysis) may develop dramatically different synchronization properties when heterogeneity is introduced with respect to neuronal excitability type....

Many networks are embedded in physical space and often interact with it. This interaction can be exemplified through constraints exerted on network topology, or through interactions of processes defined on a network with those that are linked to the space that the network is embedded within, leading to complex dynamics. Here we discuss an example o...

A period of sleep over the first few hours following single-trial contextual fear conditioning (CFC) is essential for hippocampally-mediated memory consolidation. Recent studies have uncovered intracellular mechanisms required for memory formation which are affected by post-conditioning sleep and sleep deprivation. However, almost nothing is known...

Brain networks are unique in their capacity to modify synaptic structure while at the same time modulating neuronal firing properties. We investigated the interaction of these plastic network properties with overall network dynamics in large, biophysical neuronal network models. We modulated firing properties of individual neurons by simulating cha...

Neurogenesis in the adult hippocampus is critical process in learning and memory where immature granule cells project dendrites to the molecular layer and axons to CA3 pyramidal cells[1]. While the developmental processes that govern the maturation of new granule cells have been well characterized, the manner in which the structure of the establish...

How can groups of neurons selectively encode different memories? We investigated a possible mechanism for the selective activation of regions of a network based on the resonance properties of individual neurons and het-erogeneities in the network connectivity. In network simulations of coupled resonate and fire neurons, we incorporated the experime...

Computation in the brain is often thought of as being carried out solely by neurons without regards to their supporting cells. Recent work suggests that astrocytes may play a role alongside neurons in information processing. We investigated what types of spatio-temporal patterning can be supported for such a network. Namely the astrocyte networks c...

The dynamics of neuronal networks in the brain can undergo sudden changes during an epileptic seizure. We are interested in identifying and characterizing the dynamical correlates of transition from asynchronous into synchronous network dynamics in order to detect the signatures of such a transition on the level of activity patterns of individual n...

Although sleep is a fundamental behavior observed in virtually all animal species, its functions remain unclear. One leading proposal, known as the synaptic renormalization hypothesis, suggests that sleep is necessary to counteract a global strengthening of synapses that occurs during wakefulness. Evidence for sleep-dependent synaptic downscaling (...

http://deepblue.lib.umich.edu/bitstream/2027.42/112627/1/12868_2012_Article_2523.pdf

Neuronal phase response curves (PRCs) generally fall into one of two classes. Type I PRCs exhibit exclusively phase advances and lead to decreased propensity for synchronization of excitatory networks, while Type II PRCs show regions of both phase delay and phase advance and better facilitate synchronization of excitatory networks. One little-inves...

Within the brain, the interplay between connectivity patterns of neurons and their spatiotemporal dynamics is believed to be intricately linked to the bases of behavior, such as the process of storing, consolidating, and retrieving memory traces. Memory is believed to be stored in the synaptic patterns of anatomical circuitry in the form of increas...

Neurons in the mammalian cortex have conduction latencies that can scale up an order of magnitude or more with myelination and axon radius. These latencies can be categorized into two groups: distance dependent latencies associated directly with axonic/dendritic length and distance independent latencies due to intrinsic delays on synapses themselve...

Spatiotemporal pattern formation in neuronal networks depends on the interplay between cellular and network synchronization properties. The neuronal phase response curve (PRC) is an experimentally obtainable measure that characterizes the cellular response to small perturbations, and can serve as an indicator of cellular propensity for synchronizat...

Intrinsic oscillations are thought to play important and distinct roles in cognitive processes across nearly all regions of the brain. Their specific roles are highly dependent on their properties: low-frequency θ is thought to be important in the gating of cognitive processes, while high-frequency γ is believed to be essential for binding and spik...

We describe a novel mechanism that mediates the rapid and selective pattern formation of neuronal network activity in response to changing correlations of sub-threshold level input. The mechanism is based on the classical resonance and experimentally observed phenomena that the resonance frequency of a neuron shifts as a function of membrane depola...

Networks can be dynamical systems that undergo functional and structural reorganization. One example of such a process is adult hippocampal neurogenesis, in which new cells are continuously born and incorporate into the existing network of the dentate gyrus region of the hippocampus. Many of these introduced cells mature and become indistinguishabl...

In this work we investigate the relationship between gross anatomic structural network properties, neuronal dynamics and the resultant functional structure in dissociated rat hippocampal cultures. Specifically, we studied cultures as they developed under two conditions: the first supporting glial cell growth (high glial group), and the second one i...

http://deepblue.lib.umich.edu/bitstream/2027.42/112608/1/12868_2010_Article_1746.pdf