Top-down Approach to the Investigation of the Neural Basis of Geometric-optical Illusions: Understanding the Brain as a Theoretical Entity

Resistance to distraction is a key component of executive functions and is strongly linked to the prefrontal cortex. Recent evidence suggests that neural mechanisms exist for selective suppression of task-irrelevant information. However, neuronal signals related to selective suppression have not yet been identified, whereas nonselective surround suppression, which results from attentional enhancement for relevant stimuli, has been well documented. This study examined single neuron activities in the lateral PFC when monkeys covertly tracked one of randomly moving objects. Although many neurons responded to the target, we also found a group of neurons that exhibited a selective response to the distractor that was visually identical to the target. Because most neurons were insensitive to an additional distractor that explicitly differed in color from the target, the brain seemed to monitor the distractor only when necessary to maintain internal object segregation. Our results suggest that the lateral PFC might provide at least two top–down signals during covert object tracking: one for enhancement of visual processing for the target and the other for selective suppression of visual processing for the distractor. These signals might work together to discriminate objects, thereby regulating both the sensitivity and specificity of target choice during covert object tracking.

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Frontal lobes and attention: Processes and networks, fractionation and integration

Journal of the International Neuropsychological Society ◽

10.1017/s1355617706060358 ◽

2006 ◽

Vol 12 (2) ◽

pp. 261-271 ◽

Cited By ~ 79

Author(s):

DONALD T. STUSS

Keyword(s):

Frontal Lobes ◽

Task Demands ◽

Activation Process ◽

Top Down ◽

Supervisory System ◽

Current Task ◽

Frontal Processes ◽

General Activation ◽

Lesion Studies ◽

The Brain

The frontal lobes (FL), are they a general adaptive global capacity processor, or a series of fractionated processes? Our lesion studies focusing on attention have demonstrated impairments in distinct processes due to pathology in different frontal regions, implying fractionation of the “supervisory system.” However, when task demands are manipulated, it becomes evident that the frontal lobes are not just a series of independent processes. Increased complexity of task demands elicits greater involvement of frontal regions along a fixed network related to a general activation process. For some task demands, one or more anatomically distinct frontal processes may be recruited. In other conditions, there is a bottom-up nonfrontal/frontal network, with impairment noted maximally for the lesser task demands in the nonfrontal automatic processing regions, and then as task demands change, increased involvement of different frontal (more “strategic”) regions, until it appears all frontal regions are involved. With other measures, the network is top-down, with impairment in the measure first noted in the frontal region and then, with changing task demands, involving a posterior region. Adaptability is not just a property of FL, it is the fluid recruitment of different processes anywhere in the brain as required by the current task. (JINS, 2006,12, 261–271.)

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Ex Vivo Brain Preparation to Analyze Vocal Pathways of Xenopus Frogs

Cold Spring Harbor Protocols ◽

10.1101/pdb.prot106872 ◽

2021 ◽

Vol 2021 (9) ◽

pp. pdb.prot106872

Author(s):

Ayako Yamaguchi

Keyword(s):

Neural Activity ◽

Ex Vivo ◽

Neural Circuitry ◽

Neural Basis ◽

Vocal Production ◽

Basic Principles ◽

Electrophysiological Recordings ◽

The Brain

Understanding the neural basis of behavior is a challenging task for technical reasons. Most methods of recording neural activity require animals to be immobilized, but neural activity associated with most behavior cannot be recorded from an anesthetized, immobilized animal. Using amphibians, however, there has been some success in developing in vitro brain preparations that can be used for electrophysiological and anatomical studies. Here, we describe an ex vivo frog brain preparation from which fictive vocalizations (the neural activity that would have produced vocalizations had the brain been attached to the muscle) can be elicited repeatedly. When serotonin is applied to the isolated brains of male and female African clawed frogs, Xenopus laevis, laryngeal nerve activity that is a facsimile of those that underlie sex-specific vocalizations in vivo can be readily recorded. Recently, this preparation was successfully used in other species within the genus including Xenopus tropicalis and Xenopus victorianus. This preparation allows a variety of techniques to be applied including extracellular and intracellular electrophysiological recordings and calcium imaging during vocal production, surgical and pharmacological manipulation of neurons to evaluate their impact on motor output, and tract tracing of the neural circuitry. Thus, the preparation is a powerful tool with which to understand the basic principles that govern the production of coherent and robust motor programs in vertebrates.

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Brain Stem Feedback in a Computational Model of Birdsong Sequencing

Journal of Neurophysiology ◽

10.1152/jn.91154.2008 ◽

2009 ◽

Vol 102 (3) ◽

pp. 1763-1778 ◽

Cited By ~ 16

Author(s):

Leif Gibb ◽

Timothy Q. Gentner ◽

Henry D. I. Abarbanel

Keyword(s):

Computational Model ◽

Brain Stem ◽

Thalamic Nucleus ◽

Companion Paper ◽

Neural Basis ◽

Sequence Variations ◽

Neural Feedback ◽

Uniform Expansion ◽

The Brain ◽

Feedback Pathway

Uncovering the roles of neural feedback in the brain is an active area of experimental research. In songbirds, the telencephalic premotor nucleus HVC receives neural feedback from both forebrain and brain stem areas. Here we present a computational model of birdsong sequencing that incorporates HVC and associated nuclei and builds on the model of sparse bursting presented in our preceding companion paper. Our model embodies the hypotheses that 1) different networks in HVC control different syllables or notes of birdsong, 2) interneurons in HVC not only participate in sparse bursting but also provide mutual inhibition between networks controlling syllables or notes, and 3) these syllable networks are sequentially excited by neural feedback via the brain stem and the afferent thalamic nucleus Uva, or a similar feedback pathway. We discuss the model's ability to unify physiological, behavioral, and lesion results and we use it to make novel predictions that can be tested experimentally. The model suggests a neural basis for sequence variations, shows that stimulation in the feedback pathway may have different effects depending on the balance of excitation and inhibition at the input to HVC from Uva, and predicts deviations from uniform expansion of syllables and gaps during HVC cooling.

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Spike Phase Shift Relative to Beta Oscillations Mediates Modality Selection

Cerebral Cortex ◽

10.1093/cercor/bhaa125 ◽

2020 ◽

Vol 30 (10) ◽

pp. 5431-5448

Author(s):

Yanfang Zuo ◽

Yanwang Huang ◽

Dingcheng Wu ◽

Qingxiu Wang ◽

Zuoren Wang

Keyword(s):

Phase Shift ◽

Posterior Parietal Cortex ◽

Visual Stimuli ◽

Spike Timing ◽

Male Rats ◽

Top Down ◽

Beta Oscillations ◽

Neuronal Spike ◽

Beta Power ◽

The Brain

Abstract How does the brain selectively process signals from stimuli of different modalities? Coherent oscillations may function in coordinating communication between neuronal populations simultaneously involved in such cognitive behavior. Beta power (12–30 Hz) is implicated in top-down cognitive processes. Here we test the hypothesis that the brain increases encoding and behavioral influence of a target modality by shifting the relationship of neuronal spike phases relative to beta oscillations between primary sensory cortices and higher cortices. We simultaneously recorded neuronal spike and local field potentials in the posterior parietal cortex (PPC) and the primary auditory cortex (A1) when male rats made choices to either auditory or visual stimuli. Neuronal spikes exhibited modality-related phase locking to beta oscillations during stimulus sampling, and the phase shift between neuronal subpopulations demonstrated faster top-down signaling from PPC to A1 neurons when animals attended to auditory rather than visual stimuli. Importantly, complementary to spike timing, spike phase predicted rats’ attended-to target in single trials, which was related to the animals’ performance. Our findings support a candidate mechanism that cortices encode targets from different modalities by shifting neuronal spike phase. This work may extend our understanding of the importance of spike phase as a coding and readout mechanism.

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Effects of Early-Life Stress on the Brain and Behaviors: Implications of Early Maternal Separation in Rodents

International Journal of Molecular Sciences ◽

10.3390/ijms21197212 ◽

2020 ◽

Vol 21 (19) ◽

pp. 7212

Author(s):

Mayumi Nishi

Keyword(s):

Child Abuse ◽

Hpa Axis ◽

Brain Function ◽

Life Stress ◽

Early Life ◽

Maternal Separation ◽

Early Life Stress ◽

Emotional Behavior ◽

Neural Basis ◽

The Brain

Early-life stress during the prenatal and postnatal periods affects the formation of neural networks that influence brain function throughout life. Previous studies have indicated that maternal separation (MS), a typical rodent model equivalent to early-life stress and, more specifically, to child abuse and/or neglect in humans, can modulate the hypothalamic–pituitary–adrenal (HPA) axis, affecting subsequent neuronal function and emotional behavior. However, the neural basis of the long-lasting effects of early-life stress on brain function has not been clarified. In the present review, we describe the alterations in the HPA-axis activity—focusing on serum corticosterone (CORT)—and in the end products of the HPA axis as well as on the CORT receptor in rodents. We then introduce the brain regions activated during various patterns of MS, including repeated MS and single exposure to MS at various stages before weaning, via an investigation of c-Fos expression, which is a biological marker of neuronal activity. Furthermore, we discuss the alterations in behavior and gene expression in the brains of adult mice exposed to MS. Finally, we ask whether MS repeats itself and whether intergenerational transmission of child abuse and neglect is possible.

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Re-membering the body: applications of computational neuroscience to the top-down control of regeneration of limbs and other complex organs

Integrative Biology ◽

10.1039/c5ib00221d ◽

2015 ◽

Vol 7 (12) ◽

pp. 1487-1517 ◽

Cited By ~ 48

Author(s):

G. Pezzulo ◽

M. Levin

Keyword(s):

Information Processing ◽

Pattern Formation ◽

Computational Neuroscience ◽

Memory System ◽

The Body ◽

Signaling Networks ◽

Control Mechanisms ◽

Top Down ◽

The Brain

How do regenerating bodies know when to stop remodeling? Bioelectric signaling networks guide pattern formation and may implement a somatic memory system. Deep parallels may exist between information processing in the brain and morphogenetic control mechanisms.

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When the Brain Leaves the Scanner and Enters the Clinic

Contemporary Drug Problems ◽

10.1177/0091450918774918 ◽

2018 ◽

Vol 45 (3) ◽

pp. 227-243 ◽

Cited By ~ 7

Author(s):

Anthony Barnett ◽

Ella Dilkes-Frayne ◽

Michael Savic ◽

Adrian Carter

Keyword(s):

Drug Treatment ◽

Medical Treatment ◽

Neural Basis ◽

Treatment Providers ◽

Immoral Behavior ◽

Brain Recovery ◽

Different Types ◽

Moral Condition ◽

Moral Discourses ◽

The Brain

Addiction neuroscience promises to uncover the neural basis of addiction by mapping changes in the “diseased brains” of people with “drug addictions.” It hopes to offer revolutionary treatments for addiction and reduce the stigma experienced by those seeking treatment for a medical, rather than moral, condition. While the promises of addiction neuroscience have received considerable attention, relatively few studies have examined how neuroscientific discourses and promises play out in drug treatment settings. Instead of asking how neuroscience might measure or treat a preexisting addiction “problem,” we draw on poststructuralist ideas to trace how neuroscientific discourses produce addiction as a certain type of “problem” and the effects of these particular problematizations. Based on interviews with a range of different types of treatment providers working in Victoria, Australia, we discuss three themes that reveal neuroscientific discourses at work: (1) constituting pathological subjects, (2) neuroplasticity and “recovery,” and (3) the alleviation of guilt and shame via references to the “diseased brain.” On the basis of our analysis, we argue that dominant neuroscientific discourses produce patients as pathologized subjects, requiring medical treatment. We also contend that the intersection of neuroscientific and recovery discourses enacts “recovery” in terms of brain “recovery” through references to neuroplasticity. Further, when neuroscientific and moral discourses intersect, addicted subjects are absolved from the guilt associated with immoral behavior emerging from a “hijacked brain.” We conclude by emphasizing the need for future critical work to explore the complex ways in which neuroscientific discourses operate in localized care ecologies.

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Normal Aging and the Brain

Physiology ◽

10.1152/physiologyonline.1988.3.5.197 ◽

1988 ◽

Vol 3 (5) ◽

pp. 197-200

Author(s):

R Katzman

Keyword(s):

Episodic Memory ◽

Normal Aging ◽

Intelligence Tests ◽

Neural Basis ◽

Very Old ◽

Brain Processing ◽

The Brain

During normal aging, cognition as measured by intelligence tests is remarkably preserved, although most of the very old show significant slowing of brain processing and mild loss of episodic memory. The neural basis for these changes is poorly understood.

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