scholarly journals Task-dependent modulation of SI physiological responses to targets and distractors

2013 ◽  
Vol 109 (4) ◽  
pp. 1036-1044 ◽  
Author(s):  
Elsie Spingath ◽  
Hyun-Sug Kang ◽  
David T. Blake
Keyword(s):  
Time Course ◽  
Cortical Plasticity ◽  
Task Demands ◽  
Neural Responses ◽  
Task Condition ◽  
Sensory Stimuli ◽  
Cortical Implants ◽  
Physically Identical ◽  
The Relationship ◽  
The Brain

Selective attention experimental designs have shown that neural responses to stimuli in primary somatosensory cortex are stronger when the sensory stimuli are task relevant. Other studies have used animals under no task demands for data collection. The relationship between neural responses in the brain during behavior, and while an animal has no task demands, remains underexplored. We trained two animals to perform somatosensory detection for several weeks, followed by somatosensory discrimination for several weeks. Data in response to physically identical stimuli were collected from cortical implants while the animal was under no task demands before each behavioral session and also during that behavioral session. The Fourier spectra of the field potentials during detection or discrimination compared with the no task condition demonstrated suppression of the somatosensory μ-rhythm that is associated with readiness and anticipation of cognitive use of somatosensory and motor inputs. Responses to the task target were stronger during detection and discrimination than in the no task condition. The amplitude normalized time course of the target evoked response was similar in both cases. Evoked responses to the task distractor were not significantly stronger during behavior than in recordings under no task demands. The normalized time course of the distractor responses showed a suppression that peaks 30–35 ms after the onset of the response. The selectivity of this within trial suppression is the same as the selectivity of enduring suppression evident in studies of sensory cortical plasticity, which suggests the same neural process may be responsible for both.

Simultaneous Reorganization in Thalamocortical Ensembles Evolves Over Several Hours After Perioral Capsaicin Injections

1999 ◽  
Vol 82 (2) ◽  
pp. 963-977 ◽  
Author(s):  
Donald B. Katz ◽  
S. A. Simon ◽  
Aaron Moody ◽  
Miguel A. L. Nicolelis
Keyword(s):  
Cortical Neurons ◽  
Time Course ◽  
Cortical Plasticity ◽  
Population Analysis ◽  
Receptive Fields ◽  
Somatosensory System ◽  
Spontaneous Firing ◽  
Neural Responses ◽  
Spatial Coupling ◽  
Neural Ensembles

Reorganization of the somatosensory system was quantified by simultaneously recording from single-unit neural ensembles in the whisker regions of the ventral posterior medial (VPM) nucleus of the thalamus and the primary somatosensory (SI) cortex in anesthetized rats before, during, and after injecting capsaicin under the skin of the lip. Capsaicin, a compound that excites and then inactivates a subset of peripheral C and Aδ fibers, triggered increases in spontaneous firing of thalamocortical neurons (10–15 min after injection), as well as rapid reorganization of the whisker representations in both the VPM and SI. During the first hour after capsaicin injection, 57% of the 139 recorded neurons either gained or lost at least one whisker response in their receptive fields (RFs). Capsaicin-related changes continued to emerge for ≥6 h after the injection: Fifty percent of the single-neuron RFs changed between 1–2 and 5–6 h after capsaicin injection. Most (79%) of these late changes represented neural responses that had remained unchanged in the first postcapsaicin mapping; just under 20% of these late changes appeared in neurons that had previously shown no plasticity of response. The majority of the changes (55% immediately after injection, 66% 6 h later) involved “unmasking” of new tactile responses. RF change rates were comparable in SI and VPM (57–49%). Population analysis indicated that the reorganization was associated with a lessening of the “spatial coupling” between cortical neurons—a significant reduction in firing covariance that could be related to distances between neurons. This general loss of spatial coupling, in conjunction with increases in spontaneous firing, may create a situation that is favorable for the induction of synaptic plasticity. Our results indicate that the selective inactivation of a peripheral nociceptor subpopulation can induce rapid and long-evolving (≥6 h) shifts in the balance of inhibition and excitation in the somatosensory system. The time course of these processes suggest that thalamic and cortical plasticity is not a linear reflection of spinal and brainstem changes that occur following the application of capsaicin.

The Development of Multisensory Integration in the Brain

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 35-35 ◽  
Author(s):  
M T Wallace
Keyword(s):  
Multisensory Integration ◽  
Time Course ◽  
Receptive Fields ◽  
Developmental Time ◽  
Response Latencies ◽  
Sensory Stimuli ◽  
Sensory Inputs ◽  
Response Enhancement ◽  
Sensory Responses ◽  
The Brain

Multisensory integration in the superior colliculus (SC) of the cat requires a protracted postnatal developmental time course. Kittens 3 – 135 days postnatal (dpn) were examined and the first neuron capable of responding to two different sensory inputs (auditory and somatosensory) was not seen until 12 dpn. Visually responsive multisensory neurons were not encountered until 20 dpn. These early multisensory neurons responded weakly to sensory stimuli, had long response latencies, large receptive fields, and poorly developed response selectivities. Most striking, however, was their inability to integrate cross-modality cues in order to produce the significant response enhancement or depression characteristic of these neurons in adults. The incidence of multisensory neurons increased gradually over the next 10 – 12 weeks. During this period, sensory responses became more robust, latencies shortened, receptive fields decreased in size, and unimodal selectivities matured. The first neurons capable of cross-modality integration were seen at 28 dpn. For the following two months, the incidence of such integrative neurons rose gradually until adult-like values were achieved. Surprisingly, however, as soon as a multisensory neuron exhibited this capacity, most of its integrative features were indistinguishable from those in adults. Given what is known about the requirements for multisensory integration in adult animals, this observation suggests that the appearance of multisensory integration reflects the onset of functional corticotectal inputs.

scholarly journals Dietary modulation of cortical excitation and inhibition

2017 ◽  
Vol 31 (5) ◽  
pp. 632-637 ◽  
Author(s):  
Anika K Smith ◽  
Alex R Wade ◽  
Kirsty EH Penkman ◽  
Daniel H Baker
Keyword(s):  
Dietary Intervention ◽  
Control Group ◽  
Gamma Aminobutyric Acid ◽  
Neural Responses ◽  
Dietary Interventions ◽  
Sensory Stimuli ◽  
Inhibitory Neurotransmitter ◽  
Clinical Benefits ◽  
Cortical Excitation ◽  
The Brain

The balance of excitatory and inhibitory neurotransmitters in the brain affects both neural responses and behaviour in humans and animals. Here we investigated whether dietary intervention aimed at increasing levels of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) can influence neural responses to basic sensory stimuli. Using a steady-state electroencephalography (EEG) paradigm, we found that the neural response to visual patterns was reduced in individuals who consumed a yeast extract product rich in substances associated with the production of GABA (glutamate and B vitamins), but not in a control group who consumed a placebo substance ( n = 14 per group). This demonstrates that the balance of excitation and inhibition in the brain can be influenced by dietary interventions, suggesting possible clinical benefits in conditions (e.g. epilepsy) where inhibition is abnormal.

scholarly journals A cortical circuit for abrupt visual learning in the primate brain

2021 ◽  
Author(s):  
Bennett A Csorba ◽  
Matthew Ryan Krause ◽  
Theodoros P Zanos ◽  
Christopher C Pack
Keyword(s):  
Cortical Plasticity ◽  
Visual Learning ◽  
Sensory Information ◽  
Task Demands ◽  
Visual Signals ◽  
Dramatic Improvement ◽  
Primate Brain ◽  
The Moment ◽  
Visual Cortical ◽  
The Brain

Visual cortical plasticity declines sharply after the critical period, and yet we easily learn to recognize new faces and places throughout our lives. Such learning is often characterized by a moment of insight, an abrupt and dramatic improvement in recognition. We studied the brain mechanisms that support this kind of learning, using a behavioral task in which non-human primates rapidly learned to recognize visual images and to associate them with particular responses. Simultaneous recordings from the inferotemporal and prefrontal cortices revealed a transient synchronization of neural activity between these two areas that peaked around the moment of insight. This synchronization was strongest between inferotemporal sites that encoded images and prefrontal sites that encoded rewards. Moreover, its magnitude built up gradually with successive image exposures, suggesting that abrupt learning is the culmination of a search for informative visual signals within a circuit that links sensory information to task demands.

Quantitive studies of the reactions to horizontal angular accelerations in axolotls. II. head-turning reflexes in animals with a supernumerary pair of labyrinths

1977 ◽  
Vol 66 (1) ◽  
pp. 15-31
Author(s):  
K. Brandle
Keyword(s):  
Linear Relationship ◽  
Semicircular Canal ◽  
Time Course ◽  
Reaction Threshold ◽  
Head Turning ◽  
Horizontal Semicircular Canal ◽  
Reference Parameter ◽  
Intensity Functions ◽  
The Relationship ◽  
The Brain

In axolotls (Ambystoma mexicanun) the labyrinths and the associated parts of the medulla were doubled artificially. In these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles. The head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. The form and the time-course of the reactions were almost identical in both groups. Tandem-heads showed a linear relationship between stimulus intensity and reaction strength, parallel to that in normal animals but with a greater reaction for a given stimulus. Consequent to this shift in the relationship, there was a significant decrease in the reaction threshold. The removal of one horizontal semicircular canal in tandem-heads proved that both pairs of labyrinths were functionally connected with the brain. It was suggested that during ontogenesis there exists a kind of specificity in the connexion of vestibular fibres. From the parallel shift of the intensity functions it was concluded that the input from both pairs of labyrinths in tandem-heads is not simply accumulate but compared with a reference parameter, which is also double in tandem-heads.

scholarly journals Cholinergic shaping of neural correlations

2017 ◽  
Vol 114 (22) ◽  
pp. 5725-5730 ◽  
Author(s):  
Victor Minces ◽  
Lucas Pinto ◽  
Yang Dan ◽  
Andrea A. Chiba
Keyword(s):  
Basal Forebrain ◽  
Neuronal Response ◽  
Receptive Fields ◽  
Cholinergic Neurons ◽  
Sensory Stimuli ◽  
Optogenetic Stimulation ◽  
Basal Forebrain Cholinergic Neurons ◽  
The Relationship ◽  
The Brain ◽  
Do So

A primary function of the brain is to form representations of the sensory world. Its capacity to do so depends on the relationship between signal correlations, associated with neuronal receptive fields, and noise correlations, associated with neuronal response variability. It was recently shown that the behavioral relevance of sensory stimuli can modify the relationship between signal and noise correlations, presumably increasing the encoding capacity of the brain. In this work, we use data from the visual cortex of the awake mouse watching naturalistic stimuli and show that a similar modification is observed under heightened cholinergic modulation. Increasing cholinergic levels in the cortex through optogenetic stimulation of basal forebrain cholinergic neurons decreases the dependency that is commonly observed between signal and noise correlations. Simulations of correlated neural networks with realistic firing statistics indicate that this change in the correlation structure increases the encoding capacity of the network.

scholarly journals Neural responses to naturalistic clips of behaving animals in two different task contexts

2018 ◽  
Author(s):  
Samuel A. Nastase ◽  
Yaroslav O. Halchenko ◽  
Andrew C. Connolly ◽  
M. Ida Gobbini ◽  
James V. Haxby
Keyword(s):  
Task Demands ◽  
Neural Representation ◽  
Imaging Data ◽  
Neural Responses ◽  
Test Bed ◽  
Repetition Detection ◽  
Complex Stimuli ◽  
Quality Control Metrics ◽  
Brain Imaging Data ◽  
The Brain

Neuroimaging studies of object and action representation often use controlled stimuli and implicitly assume that the relevant neural representational spaces are fixed and context-invariant. Here we present functional MRI data measured while participants freely viewed brief naturalistic video clips of behaving animals in two different task contexts. Participants performed a 1-back category repetition detection task requiring them to attend to either animal taxonomy or animal behavior. The data and analysis code are freely available, and have been curated according to the Brain Imaging Data Structure (BIDS) standard. We thoroughly describe the data, provide quality control metrics, and perform a searchlight classification analysis to demonstrate the potential utility of the data. These data are intended to provide a test bed for investigating how task demands alter the neural representation of complex stimuli and their semantic qualities.

scholarly journals Attention as Reward-Driven Optimization of Sensory Processing

2013 ◽  
Vol 25 (11) ◽  
pp. 2904-2933
Author(s):  
Matthew Chalk ◽  
Iain Murray ◽  
Peggy Seriès
Keyword(s):  
Sensory Processing ◽  
Visual Processing ◽  
Task Demands ◽  
Neural Responses ◽  
Efficient Coding ◽  
Sensory Environment ◽  
Divisive Normalization ◽  
Visual Cortices ◽  
The Brain ◽  
Visual Neuron

Attention causes diverse changes to visual neuron responses, including alterations in receptive field structure, and firing rates. A common theoretical approach to investigate why sensory neurons behave as they do is based on the efficient coding hypothesis: that sensory processing is optimized toward the statistics of the received input. We extend this approach to account for the influence of task demands, hypothesizing that the brain learns a probabilistic model of both the sensory input and reward received for performing different actions. Attention-dependent changes to neural responses reflect optimization of this internal model to deal with changes in the sensory environment (stimulus statistics) and behavioral demands (reward statistics). We use this framework to construct a simple model of visual processing that is able to replicate a number of attention-dependent changes to the responses of neurons in the midlevel visual cortices. The model is consistent with and provides a normative explanation for recent divisive normalization models of attention (Reynolds & Heeger, 2009 ).

Morphological Changes in the Brain of Acutely Ill and Weight-Recovered Patients with Anorexia Nervosa

2014 ◽  
Vol 42 (1) ◽  
pp. 7-18 ◽  
Author(s):  
Jochen Seitz ◽  
Katharina Bühren ◽  
Georg G. von Polier ◽  
Nicole Heussen ◽  
Beate Herpertz-Dahlmann ◽  
...  
Keyword(s):  
Anorexia Nervosa ◽  
Cognitive Deficits ◽  
Time Course ◽  
Morphological Changes ◽  
Meta Analysis ◽  
Short Term ◽  
Clinical Prognosis ◽  
Qualitative Review ◽  
Brain Changes ◽  
The Brain

Objective: Acute anorexia nervosa (AN) leads to reduced gray (GM) and white matter (WM) volume in the brain, which however improves again upon restoration of weight. Yet little is known about the extent and clinical correlates of these brain changes, nor do we know much about the time-course and completeness of their recovery. Methods: We conducted a meta-analysis and a qualitative review of all magnetic resonance imaging studies involving volume analyses of the brain in both acute and recovered AN. Results: We identified structural neuroimaging studies with a total of 214 acute AN patients and 177 weight-recovered AN patients. In acute AN, GM was reduced by 5.6% and WM by 3.8% compared to healthy controls (HC). Short-term weight recovery 2–5 months after admission resulted in restitution of about half of the GM aberrations and almost full WM recovery. After 2–8 years of remission GM and WM were nearly normalized, and differences to HC (GM: –1.0%, WM: –0.7%) were no longer significant, although small residual changes could not be ruled out. In the qualitative review some studies found GM volume loss to be associated with cognitive deficits and clinical prognosis. Conclusions: GM and WM were strongly reduced in acute AN. The completeness of brain volume rehabilitation remained equivocal.

Grenzenlose Verantwortung

2010 ◽  
Vol 2010 (1) ◽  
pp. 5-22
Author(s):  
Ralf Becker
Keyword(s):  
Personal Freedom ◽  
The Relationship ◽  
The Brain

The article examines the relationship between freedom, guilt and responsibility in Dostojewski’s and Sartre’s works. Both attribute a great measure of personal freedom to man. Therefore, they do not tolerate excuses. Whoever is free, carries responsibility and gets caught up in guilt. Dostojewski’s focus is mainly on guilt, Sartre’s is on responsibility. They share the conviction that we can delegate responsibility for our actions or our way of living neither to a whole, of which we are a part, like society (the ,milieu'), nor to a part, for which we are the whole, like the ,brain' or the ,genes'. In that sense, Dostojewski’s and Sartre’s attempts at an ethic of responsibility also offer convincing arguments against determinism.

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