Amygdala and Orbitofrontal engagement in breach and resolution of expectancy - a case study

ABSTRACT

Humans constantly predict their environment to facilitate mutual interaction. Predictions are connected with emotions as nonfatal penalties and rewards (for incorrect and correct expectancies, respectively) that result in negative and positive emotions. Music is an ideal stimulus to explore the underlying neurophysiological mechanisms of prediction related emotions. Using the high spatial and temporal resolution of stereotactic depth electrodes, we identified activation patterns and examined their distribution in the bilateral Amygdalae and the orbitofrontal cortex (OFC). We used music excerpts with either (a) a deceptive cadence (i.e., an unexpected chord/breach) or (b) a tonic chord inserted instead of a deceptive cadence (regular chord/no breach). These events were followed by a chord progression leading to and ending on the tonic after a breach (c) or (d) on a tonic after no breach. We computed the differences of the analytic amplitudes in the theta band at these time-points (i.e., events a–d) by using t tests. We found a significant difference between the unexpected chord (a) and the expected chord (b) in the analytic amplitude of the theta band in the left amygdala. Further we found a difference between the 2 resolutions (c and d) in the analytic amplitude of the theta band within the OFC. In conclusion, our case study supports the notion that the amygdala and the OFC are important for emotional responses to musical expectancy breaches as well as of their resolution. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

AUTHORS

• Christian Mikutta

• S. Durschmid

• Nelson Bean

• Moritz Lehne

• James Lubell

• Andreas Altorfer

• Josef Parvizi

• Werner K. Strik

• Robert T. Knight

• Stefan Koelsch

Date: 2015

DOI: dx.doi.org/10.1037/pmu0000121

Elevated synchrony in Parkinson's Disease Detected with Electroencephalography

Authors:

• N. C. Swann

• Coralie De Hemptinne

• Adam R. Aron

• Jill Ostrem

• Robert T. Knight

• Philip A. Starr

Date: 2015

DOI: 10.1002/ana.24507

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Abstract:

Objective Parkinson disease (PD) can be difficult to diagnose and treat. Development of a biomarker for PD would reduce these challenges by providing an objective measure of disease. Emerging theories suggest PD is characterized by excessive synchronization in the beta frequency band (∼20Hz) throughout basal ganglia–thalamocortical loops. Recently we showed with invasive electrocorticography that one robust measure of this synchronization is the coupling of beta phase to broadband gamma amplitude (ie, phase–amplitude coupling [PAC]). Other recent work suggests that high-frequency activity is detectable at the scalp using electroencephalography (EEG). Motivated by these findings, we tested whether beta-gamma PAC over sensorimotor cortex, recorded noninvasively with EEG, differs between PD patients off and on medications, and healthy control subjects. Methods Resting EEG was compared from 15 PD patients and 16 healthy control subjects. PD patients were tested on and off medications on different days, in a counterbalanced order. For each data set we calculated PAC and compared results across groups. Results PAC was elevated in the patients off medications compared to on medications (p = 0.008) and for patients off medications compared to controls (p = 0.009). Interpretation Elevated PAC is detectable using scalp EEG in PD patients off medications compared to on medications, and compared to healthy controls. This suggests that EEG PAC may provide a noninvasive biomarker of the parkinsonian state. This biomarker could be used as a control signal for closed-loop control of deep brain stimulation devices, for adjustment of dopaminergic treatment, and also has the potential to aid in diagnosis. Ann Neurol 2015

Memory in Music and Emotions

ABSTRACT

Music is a basic and ancient feature of human socialization. Music is a powerful inducer of emotions , and humans appear to listen to music specifically because of this. It was shown that emotion is a powerful modulator of memory encoding. The following chapter provides an overview over music specific encoding mechanisms in the short- and long-term memory. Hereby music specific features of working memory model as well as the interaction of the acceding auditory pathways, music processing and memory encoding are discussed. Furthermore, we show the overlap and the differences between language and music memory. The impact of music-induced emotions on memory encoding is explored. Finally music’s ability to reveal autobiographic memories is summarized.

AUTHORS

• Christian Mikutta

• Werner K. Strik

• Robert T. Knight

• Andreas Altorfer

Date: 2015

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Sustained attention and prediction: distinct brain maturation trajectories during adolescence

ABSTRACT

Adolescence is a key period for frontal cortex maturation necessary for the development of cognitive ability. Sustained attention and prediction are cognitive functions critical for optimizing sensory processing, and essential to efficiently adapt behaviors in an ever-changing world. The aim of the current study was to investigate the brain developmental trajectories of attentive and predictive processing through adolescence. We recorded EEG in 36 participants from the age of 12–24 years (three age groups: 12–14, 14–17, 18–24 years) to target development during early and late adolescence, and early adulthood. We chose a visual target detection task which loaded upon sustained attention, and we manipulated target predictability. Continued maturation of sustained attention after age 12 was evidenced by improved performance (hits, false alarms (FAs) and sensitivity) in a detection task, associated with a frontal shift in the scalp topographies of the Contingent Negative Variation (CNV) and P3 responses, with increasing age. No effect of age was observed on predictive processing, with all ages showing similar benefits in reaction time, increases in P3 amplitude (indexing predictive value encoding and memorization), increases in CNV amplitude (corresponding to prediction implementation) and reduction in target-P3 latency (reflecting successful prediction building and use), with increased predictive content. This suggests that adolescents extracted and used predictive information to generate predictions as well as adults. The present results show that predictive and attentive processing follow distinct brain developmental trajectories: prediction abilities seem mature by the age of 12 and sustained attention continues to improve after 12-years of age and is associated with maturational changes in the frontal cortices.

AUTHORS

• Alix Thillay

• S. Roux

• Valerie Gissot

• Isabelle Carteau-Martin

• Robert T. Knight

• Frederique Bonnet-Brilhault

• Aurélie Bidet-Caulet

Date: 2015

DOI: 10.3389/fnhum.2015.00519, 2015

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Age-Related Changes in 1/f Neural Electrophysiological Noise

ABSTRACT

Aging is associated with performance decrements across multiple cognitive domains. The neural noise hypothesis, a dominant view of the basis of this decline, posits that aging is accompanied by an increase in spontaneous, noisy baseline neural activity. Here we analyze data from two different groups of human subjects: intracranial electrocorticography from 15 participants over a 38 year age range (15–53 years) and scalp EEG data from healthy younger (20 –30 years) and older (60 –70 years) adults to test the neural noise hypothesis from a 1/f noise perspective. Many natural phenomena, including electrophysiology, are characterized by 1/f noise. The defining characteristic of 1/f is that the power of the signal frequency content decreases rapidly as a function of the frequency ( f ) itself. The slope of this decay, the noise exponent (), is often1 for electrophysiological data and has been shown to approach white noise (defined as  0) with increasing task difficulty.Weobserved, in both electrophysiological datasets, that aging is associated with a flatter (more noisy) 1/f power spectral density, even at rest, and that visual cortical 1/f noise statistically mediates age-related impairments in visual working memory. These results provide electrophysiological support for the neural noise hypothesis of aging.

AUTHORS

• Bradley Voytek

• Mark A. Kramer

• John Case

• Kyle Q. Lepage

• Zachary Tempesta

• Robert T. Knight

• Adam Gazzaley

Date: 2015

DOI: 10.1523/JNEUROSCI.2332-14.2015

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Task-related activity in sensorimotor cortex in Parkinson’s disease and essential tremor: changes in beta and gamma bands

Authors:

• Nathan C. Rowland

• Coralie De Hemptinne

• N. C. Swann

• Qasim Salman

• Svjetlana Miocinovic

• Jill Ostrem

• Robert T. Knight

• Philip A. Starr

Date: 2015

DOI: 10.3389/fnhum.2015.00512

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Abstract:

In Parkinson's disease patients in the OFF medication state, basal ganglia local field potentials exhibit changes in beta and gamma oscillations that correlate with reduced voluntary movement, manifested as rigidity and akinesia. However, magnetoencephalography and low-resolution electrocorticography (ECoG) studies in Parkinson's patients suggest that changes in sensorimotor cortical oscillations differ from those of the basal ganglia. To more clearly define the role of sensorimotor cortex oscillatory activity in Parkinson's, we performed intraoperative, high-resolution (4 mm spacing) ECoG recordings in 10 Parkinson's patients (2 females, ages 47–72) undergoing deep brain stimulation (DBS) lead placement in the awake, OFF medication state. We analyzed ECoG potentials during a computer-controlled reaching task designed to separate movement preparation from movement execution and compared findings to similar invasive recordings in eight patients with essential tremor (3 females, ages 59–78), a condition not associated with rigidity or akinesia. We show that (1) cortical beta spectral power at rest does not differ between Parkinson's and essential tremor patients (p = 0.85), (2) early motor preparation in Parkinson's patients in the OFF medication state is associated with a larger beta desynchronization compared to patients with essential tremor (p = 0.0061), and (3) cortical broadband gamma power is elevated in Parkinson's patients compared to essential tremor patients during both rest and task recordings (p = 0.004). Our findings suggest an oscillatory profile in sensorimotor cortex of Parkinson's patients that, in contrast to the basal ganglia, may act to promote movement to oppose the anti-kinetic bias of the dopamine-depleted state.

Where Does One Stand: A Biological Account of Preferred Interpersonal Distance

Authors:

• Anat Perry

• Nikolay Nichiporuk

• Robert T. Knight

Date: 2015

DOI: 10.1093/scan/nsv115

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Abstract:

What determines how close you choose to stand to someone? Why do some people prefer farther distances than others? We hypothesized that an important factor is one's sensory sensitivity level, i.e. how sensitive one is to nearby visual stimulation, noise, touch or smell. The current study characterizes the behavioral, hormonal and electrophysiological metrics of interpersonal distance (IPD) preferences in relation to levels of sensory sensitivity. Using both an ecologically realistic task and EEG we found that sensory sensitivity levels predicted IPD preferences, such that the more sensitive one is the farther distance they prefer. Furthermore, electrophysiological evidence revealed that individuals with higher sensory sensitivity show more alpha suppression for approaching stimuli, strengthening the notion that early sensory cortical excitability is involved in one's social decision of how close to stand to another. The results provide evidence that a core human metric of social interaction is influenced by individual levels of sensory sensitivity.

How to stop or change a motor response: Laplacian and independent component approach

Authors:

• M. Rangel-Gomez

• Robert T. Knight

• Ulrike M. Krämer

Date: 2015

DOI: 10.1016/j.ijpsycho.2015.01.012

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Abstract:

Response inhibition is an essential control function necessary to adapt one's behavior. This key cognitive capacity is assumed to be dependent on the prefrontal cortex and basal ganglia. It is unresolved whether varying inhibitory demands engage different control mechanisms or whether a single motor inhibitory mechanism is involved in any situation. We addressed this question by comparing electrophysiological activity in conditions that require stopping a response to conditions that require switching to an alternate response. Analyses of electrophysiological data obtained from stop-signal tasks are complicated by overlapping stimulus-related activity that is distributed over frontal and parietal cortical recording sites. Here, we applied Laplacian transformation and independent component analysis (ICA) to overcome these difficulties. Participants were faster in switching compared to stopping a response, but we did not observe differences in neural activity between these conditions. Both stop- and change-trials Laplacian transformed ERPs revealed a comparable bilateral parieto-occipital negativity around 180 ms and a frontocentral negativity around 220 ms. ICA results suggested an inhibition-related frontocentral component which was characterized by a negativity around 200 ms with a likely source in anterior cingulate cortex. The data provide support for the importance of posterior medial frontal areas in inhibitory response control and are consistent with a common neural pathway underlying stopping and changing of a motor response. The methodological approach proved useful to distinguish frontal and parietal sources despite similar timing and the ICA approach allowed assessment of single-trial data with respect to behavioral data.

Oscillatory dynamics coordinating human frontal networks in support of goal maintenance

Abstract:

Humans have a capacity for hierarchical cognitive control—the ability to simultaneously control immediate actions while holding more abstract goals in mind. Neuropsychological and neuroimaging evidence suggests that hierarchical cognitive control emerges from a frontal architecture whereby prefrontal cortex coordinates neural activity in the motor cortices when abstract rules are needed to govern motor outcomes. We utilized the improved temporal resolution of human intracranial electrocorticography to investigate the mechanisms by which frontal cortical oscillatory networks communicate in support of hierarchical cognitive control. Responding according to progressively more abstract rules resulted in greater frontal network theta phase encoding (4–8 Hz) and increased prefrontal local neuronal population activity (high gamma amplitude, 80–150 Hz), which predicts trial-by-trial response times. Theta phase encoding coupled with high gamma amplitude during inter-regional information encoding, suggesting that inter-regional phase encoding is a mechanism for the dynamic instantiation of complex cognitive functions by frontal cortical subnetworks.

Authors:

• Bradley Voytek

• Andrew S. Kayser

• David Badre

• David Fegen

• Edward F. Chang

• Nathan E. Crone

• Josef Parvizi

• Robert T. Knight

• Mark D'Esposito

Date: 2015

DOI: 10.1038/nn.4071

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Specifying the role of the left prefrontal cortex in word selection

Abstract:

Word selection allows us to choose words during language production. This is often viewed as a competitive process wherein a lexical representation is retrieved among semantically-related alternatives. The left prefrontal cortex (LPFC) is thought to help overcome competition for word selection through top-down control. However, whether the LPFC is always necessary for word selection remains unclear. We tested 6 LPFC-injured patients and controls in two picture naming paradigms varying in terms of item repetition. Both paradigms elicited the expected semantic interference effects (SIE), reflecting interference caused by semantically-related representations in word selection. However, LPFC patients as a group showed a larger SIE than controls only in the paradigm involving item repetition. We argue that item repetition increases interference caused by semantically-related alternatives, resulting in increased LPFC-dependent cognitive control demands. The remaining network of brain regions associated with word selection appears to be sufficient when items are not repeated.

Authors:

• Stephanie Ries

• C.R. Karzmark

• E. Navarrete

• Robert T. Knight

• Nina F. Dronkers

Date: 2015

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Thalamic theta phase alignment predicts human memory formation and anterior thalamic cross-frequency coupling

Authors:

• Catherine M. Sweeney-Reed

• Tino Zaehle

• Jürgen Voges

• Friedhelm Schmitt

• Lars Buentjen

• Klaus Kopitzki

• Hermann Hinrichs

• Hans-Jochen Heinze

• Michael D. Rugg

• Robert T. Knight

• Alan Richardson-Klavehn

Date: 2015

DOI: 10.7554/eLife.07578

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Abstract:

Previously we reported electrophysiological evidence for a role for the anterior thalamic nucleus (ATN) in human memory formation (Sweeney-Reed et al. 2014). Theta-gamma cross-frequency coupling (CFC) predicted successful memory formation, with the involvement of gamma oscillations suggesting memory-relevant local processing in the ATN. The importance of the theta frequency range in memory processing is well-established, and phase alignment of oscillations is considered to be necessary for synaptic plasticity. We hypothesized that theta phase alignment in the ATN would be necessary for memory encoding. Further analysis of the electrophysiological data reveal that phase alignment in the theta rhythm was greater during successful compared with unsuccessful encoding, and that this alignment was correlated with the CFC. These findings support an active processing role for the ATN during memory formation.

Redefining the role of Broca’s area in speech

Authors:

• Adeen Flinker

• Anna Korzeniewska

• Avgusta Shestyuk

• Piotr Franaszczuk

• Nina F. Dronkers

• Robert T. Knight

• Nathan E. Crone

Date: 2015

DOI: 10.1073/pnas.1414491112

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Abstract:

For over a century neuroscientists have debated the dynamics by which human cortical language networks allow words to be spoken. Although it is widely accepted that Broca’s area in the left inferior frontal gyrus plays an important role in this process, it was not possible, until recently, to detail the timing of its recruitment relative to other language areas, nor how it interacts with these areas during word production. Using direct cortical surface recordings in neurosurgical patients, we studied the evolution of activity in cortical neuronal populations, as well as the Granger causal interactions between them. We found that, during the cued production of words, a temporal cascade of neural activity proceeds from sensory representations of words in temporal cortex to their corresponding articulatory gestures in motor cortex. Broca’s area mediates this cascade through reciprocal interactions with temporal and frontal motor regions. Contrary to classic notions of the role of Broca’s area in speech, while motor cortex is activated during spoken responses, Broca’s area is surprisingly silent. Moreover, when novel strings of articulatory gestures must be produced in response to non- word stimuli, neural activity is enhanced in Broca’s area, but not in motor cortex. These unique data provide evidence that Broca’s area coordinates the transformation of information across large-scale cortical networks involved in spoken word production. In this role, Broca’s area formulates an appropriate articulatory code to be implemented by motor cortex.

Intracranial recordings and human memory

Authors:

• Elizabeth L. Johnson

• Robert T. Knight

Date: 2015

DOI: 10.1016/j.conb.2014.07.021

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Abstract:

Recent work involving intracranial recording during human memory performance provides superb spatiotemporal resolution on mnemonic processes. These data demonstrate that the cortical regions identified in neuroimaging studies of memory fall into temporally distinct networks and the hippocampal theta activity reported in animal memory literature also plays a central role in human memory. Memory is linked to activity at multiple interacting frequencies, ranging from 1 to 500 Hz. High-frequency responses and coupling between different frequencies suggest that frontal cortex activity is critical to human memory processes, as well as a potential key role for the thalamus in neocortical oscillations. Future research will inform unresolved questions in the neuroscience of human memory and guide creation of stimulation protocols to facilitate function in the damaged brain.

Necessary, Yet Dissociable Contributions of the Insular and Ventromedial Prefrontal Cortices to Norm Adaptation: Computational and Lesion Evidence in Humans

Authors:

• Xiaosi Gu

• Xingchao Wang

• Andreas Hula

• Shiwei Wang

• Shuai Xu

• Terry Lohrenz

• Robert T. Knight

• Zhixian Gao

• Peter Dayan

• P. Read Montague

Date: 2015

DOI: 10.1523/JNEUROSCI.2906-14.2015

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Abstract:

Social norms and their enforcement are fundamental to human societies. The ability to detect deviations from norms and to adapt to norms in a changing environment is therefore important to individuals’ normal social functioning. Previous neuroimaging studies have highlighted the involvement of the insular and ventromedial prefrontal (vmPFC) cortices in representing norms. However, the necessity and dissociability of their involvement remain unclear. Using model-based computational modeling and neuropsychological lesion approaches, we examined the contributions of the insula and vmPFC to norm adaptation in seven human patients with focal insula lesions and six patients with focal vmPFC lesions, in comparison with forty neurologically intact controls and six brain-damaged controls. There were three computational signals of interest as participants played a fairness game (ultimatum game): sensitivity to the fairness of offers, sensitivity to deviations from expected norms, and the speed at which people adapt to norms. Significant group differences were assessed using bootstrapping methods. Patients with insula lesions displayed abnormally low adaptation speed to norms, yet detected norm violations with greater sensitivity than controls. Patients with vmPFC lesions did not have such abnormalities, but displayed reduced sensitivity to fairness and were more likely to accept the most unfair offers. These findings provide compelling computational and lesion evidence supporting the necessary, yet dissociable roles of the insula and vmPFC in norm adaptation in humans: the insula is critical for learning to adapt when reality deviates from norm expectations, and that the vmPFC is important for valuation of fairness during social exchange.

The electrophysiology of language production: what could be improved

Authors:

• Vitoria Piai

• Stephanie Ries

• Robert T. Knight

Date: 2015

DOI: 10.3389/fpsyg.2014.01560

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Abstract:

Recently, the field of spoken-word production has seen an increasing interest in the use of the electroencephalogram (EEG), mainly for event-related potentials (ERPs). These are exciting times to be a language production researcher. However, no matter how much we would like our results to speak to our theories, they can only do so if our methods are formally correct and valid, and reported in ways that allow replicability. Inappropriate practices in signal processing and statistical testing, when applied to our investigations, may render our conclusions invalid or non-generalizable. Here, we first present some issues in signal processing and statistical testing that we think deserve more attention when analysing data, reporting results, and making inferences. These issues are not new to electrophysiology, so our sole contribution is to reiterate them in order to provide pointers to literature where they have been discussed in more detail and solutions have been proposed. We then discuss other issues pertinent to our investigations of overt word-production because of the effects (and potential confounds) that speaking will have on the signal. Although we cannot provide answers to some of the issues raised, we invite researchers in the field to jointly work on solutions so that the topic of the electrophysiology of word production can thrive on solid grounds.

Sensory Deviancy Detection Measured Directly Within the Human Nucleus Accumbens

Authors:

• S. Durschmid

• Tino Zauhle

• Hermann Hinrichs

• Hans-Jochen Heinze

• Jürgen Voges

• Marta Garrido

• Raymond J. Dolan

• Robert T. Knight

Date: 2015

DOI: 10.1093/cercor/bhu304

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Abstract:

Rapid changes in the environment evoke a comparison between expectancy and actual outcome to inform optimal subsequent behavior. The nucleus accumbens (NAcc), a key interface between the hippocampus and neocortical regions, is a candidate region for mediating this comparison. Here, we report event-related potentials obtained from the NAcc using direct intracranial recordings in 5 human participants while they listened to trains of auditory stimuli differing in their degree of deviation from repetitive background stimuli. NAcc recordings revealed an early mismatch signal (50–220 ms) in response to all deviants. NAcc activity in this time window was also sensitive to the statistics of stimulus deviancy, with larger amplitudes as a function of the level of deviancy. Importantly, this NAcc mismatch signal also predicted generation of longer latency scalp potentials (300–400 ms). The results provide direct human evidence that the NAcc is a key component of a network engaged in encoding statistics of the sensory environmental.

Decoding Speech for Understanding and Treating Aphasia

Authors:

• Brian Pasley

• Robert T. Knight

Date: 2015

DOI: 10.1016/B978-0-444-63327-9.00018-7

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Abstract:

Aphasia is an acquired language disorder with a diverse set of symptoms that can affect virtually any linguistic modality across both the comprehension and production of spoken language. Partial recovery of language function after injury is common but typically incomplete. Rehabilitation strategies focus on behavioral training to induce plasticity in underlying neural circuits to maximize linguistic recovery. Understanding the different neural circuits underlying diverse language functions is a key to developing more effective treatment strategies. This chapter discusses a systems identification analytic approach to the study of linguistic neural representation. The focus of this framework is a quantitative, model-based characterization of speech and language neural representations that can be used to decode, or predict, speech representations from measured brain activity. Recent results of this approach are discussed in the context of applications to understanding the neural basis of aphasia symptoms and the potential to optimize plasticity during the rehabilitation process.