Regional and Laminar Differences in In Vivo Firing Patterns of Primate Cortical Neurons

2005 ◽  
Vol 94 (1) ◽  
pp. 567-575 ◽  
Author(s):  
Shigeru Shinomoto ◽  
Youichi Miyazaki ◽  
Hiroshi Tamura ◽  
Ichiro Fujita
Keyword(s):  
Cortical Neurons ◽  
Temporal Cortex ◽  
Local Variation ◽  
Inferior Temporal Cortex ◽  
Regular Type ◽  
Cortical Areas ◽  
Different Types ◽  
Area Te ◽  
Firing Characteristics

The firing rates of cortical neurons change in time; yet, some aspects of their in vivo firing characteristics remain unchanged and are specific to individual neurons. A recent study has shown that neurons in the monkey medial motor areas can be grouped into 2 firing types, “likely random” and “quasi-regular,” according to a measure of local variation of interspike intervals. In the present study, we extended this analysis to area TE of the inferior temporal cortex and addressed whether this classification applies generally to different cortical areas and whether different types of neurons show different laminar distribution. We found that area TE did consist of 2 groups of neurons with different firing characteristics, one similar to the “likely random” type in the medial motor cortical areas, and the other exhibiting a “clumpy-bursty” firing pattern unique to TE. The quasi-regular type was rarely observed in area TE. The likely random firing type of neuron was more frequently found in layers V–VI than in layers II–III, whereas the opposite was true for the clumpy-bursty firing type. These results show that neocortical areas consist of heterogeneous neurons that differ from one area to another in their basic firing characteristics. Moreover, we show that spike trains obtained from a single cortical neuron can provide a clue that helps to identify its layer localization.

scholarly journals Cortical neurons exhibit diverse myelination patterns that scale between mouse brain regions and regenerate after demyelination

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cody L. Call ◽  
Dwight E. Bergles
Keyword(s):  
Cortical Neurons ◽  
Regional Differences ◽  
Brain Regions ◽  
Axon Diameter ◽  
Neuronal Identity ◽  
Cortical Areas ◽  
Myelin Sheaths ◽  
Parvalbumin Interneurons ◽  
Selection Of

ABSTRACTAxons in the cerebral cortex show a broad range of myelin coverage. Oligodendrocytes establish this pattern by selecting a cohort of axons for myelination; however, the distribution of myelin on distinct neurons and extent of internode replacement after demyelination remain to be defined. Here we show that myelination patterns of seven distinct neuron subtypes in somatosensory cortex are influenced by both axon diameter and neuronal identity. Preference for myelination of parvalbumin interneurons was preserved between cortical areas with varying myelin density, suggesting that regional differences in myelin abundance arises through local control of oligodendrogenesis. By imaging loss and regeneration of myelin sheaths in vivo we show that myelin distribution on individual axons was altered but overall myelin content on distinct neuron subtypes was restored. Our findings suggest that local changes in myelination are tolerated, allowing regenerated oligodendrocytes to restore myelin content on distinct neurons through opportunistic selection of axons.

scholarly journals Association Between Visual Memory and In Vivo Amyloid and Tau Pathology in Preclinical Autosomal Dominant Alzheimer’s Disease

2020 ◽  
pp. 1-9
Author(s):  
Yamile Bocanegra ◽  
Joshua T. Fox-Fuller ◽  
Ana Baena ◽  
Edmarie Guzmán-Vélez ◽  
Clara Vila-Castelar ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Verbal Memory ◽  
Visual Memory ◽  
Autosomal Dominant ◽  
Clinical Symptoms ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Amyloid Burden

Abstract Objective: Visual memory (ViM) declines early in Alzheimer’s disease (AD). However, it is unclear whether ViM impairment is evident in the preclinical stage and relates to markers of AD pathology. We examined the relationship between ViM performance and in vivo markers of brain pathology in individuals with autosomal dominant AD (ADAD). Methods: Forty-five cognitively unimpaired individuals from a Colombian kindred with the Presenilin 1 (PSEN1) E280A ADAD mutation (19 carriers and 26 noncarriers) completed the Rey–Osterrieth Complex Figure immediate recall test, a measure of ViM. Cortical amyloid burden and regional tau deposition in the entorhinal cortex (EC) and inferior temporal cortex (IT) were measured using 11C-Pittsburgh compound B positron emission tomography (PET) and 11F-flortaucipir PET, respectively. Results: Cognitively unimpaired carriers and noncarriers did not differ on ViM performance. Compared to noncarriers, carriers had higher levels of cortical amyloid and regional tau in both the EC and IT. In cognitively unimpaired carriers, greater cortical amyloid burden, higher levels of regional tau, and greater age were associated with worse ViM performance. Only a moderate correlation between regional tau and ViM performance remained after adjusting for verbal memory scores. None of these correlations were observed in noncarriers. Conclusions: Results suggest that AD pathology and greater age are associated with worse ViM performance in ADAD before the onset of clinical symptoms. Further investigation with larger samples and longitudinal follow-up is needed to examine the utility of ViM measures for identifying individuals at high risk of developing dementia later in life.

Presumed Inhibitory Neurons in the Macaque Inferior Temporal Cortex: Visual Response Properties and Functional Interactions With Adjacent Neurons

2004 ◽  
Vol 91 (6) ◽  
pp. 2782-2796 ◽  
Author(s):  
Hiroshi Tamura ◽  
Hidekazu Kaneko ◽  
Keisuke Kawasaki ◽  
Ichiro Fujita
Keyword(s):  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Inhibitory Neurons ◽  
Visual Features ◽  
Similar Degree ◽  
Visual Response ◽  
Response Properties ◽  
Cross Correlation Analysis ◽  
Area Te

Neurons in area TE of the monkey inferior temporal cortex respond selectively to images of particular objects or their characteristic visual features. The mechanism of generation of the stimulus selectivity, however, is largely unknown. This study addresses the role of inhibitory TE neurons in this process by examining their visual response properties and interactions with adjacent target neurons. We applied cross-correlation analysis to spike trains simultaneously recorded from pairs of adjacent neurons in anesthetized macaques. Neurons whose activity preceded a decrease in activity from their partner were presumed to be inhibitory neurons. Excitatory neurons were also identified as the source neuron of excitatory linkage as evidenced by a sharp peak displaced from the 0-ms bin in cross-correlograms. Most inhibitory neurons responded to a variety of visual stimuli in our stimulus set, which consisted of several dozen geometrical figures and photographs of objects, with a clear stimulus preference. On average, 10% of the stimuli increased firing rates of the inhibitory neurons. Both excitatory and inhibitory neurons exhibited a similar degree of stimulus selectivity. Although inhibitory neurons occasionally shared the most preferred stimuli with their target neurons, overall stimulus preferences were less similar between adjacent neurons with inhibitory linkages than adjacent neurons with common inputs and/or excitatory linkages. These results suggest that inhibitory neurons in area TE are activated selectively and exert stimulus-specific inhibition on adjacent neurons, contributing to shaping of stimulus selectivity of TE neurons.

scholarly journals Against memory systems

2002 ◽  
Vol 357 (1424) ◽  
pp. 1111-1121 ◽  
Author(s):  
David Gaffan
Keyword(s):  
Temporal Lobe ◽  
Cortical Neurons ◽  
Medial Temporal Lobe ◽  
Temporal Cortex ◽  
Memory Systems ◽  
Memory System ◽  
Memory Processing ◽  
Multiple Memory Systems ◽  
Cortical Areas ◽  
Severe Impairment

The medial temporal lobe is indispensable for normal memory processing in both human and non–human primates, as is shown by the fact that large lesions in it produce a severe impairment in the acquisition of new memories. The widely accepted inference from this observation is that the medial temporal cortex, including the hippocampal, entorhinal and perirhinal cortex, contains a memory system or multiple memory systems, which are specialized for the acquisition and storage of memories. Nevertheless, there are some strong arguments against this idea: medial temporal lesions produce amnesia by disconnecting the entire temporal cortex from neuromodulatory afferents arising in the brainstem and basal forebrain, not by removing cortex; the temporal cortex is essential for perception as well as for memory; and response properties of temporal cortical neurons make it impossible that some kinds of memory trace could be stored in the temporal lobe. All cortex is plastic, and it is possible that the same rules of plasticity apply to all cortical areas; therefore, memory traces are stored in widespread cortical areas rather than in a specialized memory system restricted to the temporal lobe. Among these areas, the prefrontal cortex has an important role in learning and memory, but is best understood as an area with no specialization of function.

Temporal encoding of two-dimensional patterns by single units in primate primary visual cortex. II. Information transmission

1990 ◽  
Vol 64 (2) ◽  
pp. 370-380 ◽  
Author(s):  
B. J. Richmond ◽  
L. M. Optican
Keyword(s):  
Cortical Neurons ◽  
Activity Patterns ◽  
Temporal Cortex ◽  
Principal Component ◽  
Response Strength ◽  
Inferior Temporal Cortex ◽  
Temporal Code ◽  
Response Code ◽  
Stimulus Response ◽  
Black And White

1. Previously, we studied how picture information was processed by neurons in inferior temporal cortex. We found that responses varying in both response strength and temporal waveform carried information about briefly flashed stationary black-and-white patterns. Now, we have applied that same paradigm to the study of striate cortical neurons. 2. In this approach the responses to a set of basic black and white pictures were quantified through use of a set of basic waveforms, the principal components (extracted from all the responses of each neuron). We found that the first principal component, which corresponds to the response strength, and others, which correspond to different basic temporal activity patterns, were significantly related to the stimuli, i.e., the stimulus drove both the response strength and its temporal pattern. 3. Our previous study had shown that, when information theory was used to quantify the stimulus-response relation, inferior temporal neurons convey over twice as much information in a response code that includes temporal modulation as in a response code that includes only the response strength. This study shows that striate cortical neurons also carry twice as much information in a temporal code as in a response strength code. Thus single visual neurons at both ends of a cortical processing chain for visual pattern use a multidimensional temporal code to carry stimulus-related information. 4. These results support our multiplex-filter hypothesis, which states that single visual system neurons can be regarded as several simultaneously active parallel channels, each of which conveys independent information about the stimulus.

scholarly journals Excess interictal activity marks seizure prone cortical areas and mice in a genetic epilepsy model

2021 ◽  
Author(s):  
William F Tobin ◽  
Matthew Weston
Keyword(s):  
Cortical Neurons ◽  
Cortical Activity ◽  
Epileptic Encephalopathy ◽  
K Channel ◽  
Future Research ◽  
Dorsal Cortex ◽  
Cortical Areas ◽  
Epileptiform Discharges ◽  
Spontaneous Seizures

Genetic epilepsies are often caused by variants in widely expressed genes, potentially impacting numerous brain regions and functions. For instance, gain-of-function (GOF) variants in the widely expressed Na+-activated K+ channel gene KCNT1 alter basic neurophysiological and synaptic properties of cortical neurons, leading to developmental epileptic encephalopathy. Yet, aside from causing seizures, little is known about how such variants reshape interictal brain activity, and how this relates to epileptic activity and other disease symptoms. To address this knowledge gap, we monitored neural activity across the dorsal cortex in a mouse model of human KCNT1-related epilepsy using in vivo, awake widefield Ca2+ imaging. We observed 52 spontaneous seizures and 1700 interictal epileptiform discharges (IEDs) in homozygous mutant (Kcnt1m/m) mice, allowing us to map their appearance and spread at high spatial resolution. Outside of seizures and IEDs, we detected ~46,000 events, representing interictal cortical activity, in both Kcnt1m/m and wild-type (WT) mice, and we classified them according to their spatial profiles. Spontaneous seizures and IEDs emerged within a consistent set of susceptible cortical areas, and seizures propagated both contiguously and non-contiguously within these areas in a manner influenced, but not fully determined, by underlying synaptic connectivity. Seizure emergence was predicted by a progressive concentration of total cortical activity within the impending seizure emergence zone. Outside of seizures and IEDs, similar events were detected in WT and Kcnt1m/m mice, suggesting that the spatial structure of interictal activity was largely preserved. Several features of these events, however, were altered in Kcnt1m/m mice. Most event types were briefer, and their intensity more variable, across Kcnt1m/m mice; mice showing more intense activity spent more time in seizure. Furthermore, the rate of events whose spatial profile overlapped with where seizures and IEDs emerged was increased in Kcnt1m/m mice. Taken together, these results demonstrate that an epilepsy-causing K+ channel variant broadly alters physiology. Yet, outside of seizures and IEDs, it acts not to produce novel types of cortical activity, but rather to modulate its amount. The areas where seizures and IEDs emerge show excessively frequent and intense interictal activity and the mean intensity of an individual's cortical activity predicts its seizure burden. These findings provide critical guidance for targeting future research and therapy development.

Effect of Motion on the Recognition of Area by Rhesus Monkeys in a Pseudo-Matching Task

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 249-249
Author(s):  
H Malecki ◽  
S G Rosolen ◽  
R Bonnier
Keyword(s):  
Rhesus Monkeys ◽  
Visual Recognition ◽  
Temporal Cortex ◽  
The Other ◽  
Inferior Temporal Cortex ◽  
Matching Task ◽  
Target Area ◽  
Target Speed ◽  
Cortical Areas ◽  
Better Than

We examined the effect of target motion on the visual recognition of target area in rhesus monkeys. We used a pseudo-matching visual task, where ten adult monkeys were trained to recognise and point out the bigger one of two achromatic squares of different areas but having the same luminance and presented on the same background. The video screen was placed 0.5 m in front of their faces. The two areas were randomly sampled out of five areas (49, 72.25, 100, 132.25, and 169 mm2). The speed of the targets was varied in this paradigm (0, 6, 11, 16, 21, or 26 deg s−1). Performance in terms of area recognition thresholds was calculated for each monkey on the basis of 100 trials in standardised environmental conditions. Statistical analysis showed that performance with a target speed of 16 deg s−1 was significantly better than in the other conditions ( p<0.01). We conclude that this pseudo-matching task, based on a cognitive paradigm, reveals a significant effect of motion on the visual recognition of area in rhesus monkeys. The activities of specific cortical areas (V4 and V5) should be studied by other techniques in order to characterise those involved in remembering an object's qualities and those responding to motion. The links between V4, V5, and inferior temporal cortex could be tested with the aid of this pseudo-matching task.

Functional Double Dissociation Between Two Inferior Temporal Cortical Areas: Perirhinal Cortex Versus Middle Temporal Gyrus

1997 ◽  
Vol 77 (2) ◽  
pp. 587-598 ◽  
Author(s):  
M. J. Buckley ◽  
D. Gaffan ◽  
E. A. Murray
Keyword(s):  
Performance Test ◽  
Temporal Cortex ◽  
Color Discrimination ◽  
Perirhinal Cortex ◽  
Inferior Temporal Cortex ◽  
Middle Temporal Gyrus ◽  
Middle Temporal ◽  
Postoperative Performance ◽  
Double Dissociation ◽  
Cortical Areas

Buckley, M. J., D. Gaffan, and E. A. Murray. Functional double dissociation between two inferior temporal cortical areas: perirhinal cortex versus middle temporal gyrus. J. Neurophysiol. 77: 587–598, 1997. There is both anatomic and cytoarchitectural evidence for dorsal-ventral subdivisions of the inferior temporal cortex. Despite this, there has been only limited evidence of corresponding functional subdivisions and no evidence that two adjacent cortical areas within the inferior temporal cortex, namely area TE and the perirhinal cortex, have distinctly different roles in vision and memory. We assessed the color discrimination abilities of cynomolgus monkeys with either bilateral ablation of the perirhinal cortex or bilateral ablation of the middle temporal gyrus. The stimuli were isoluminant colored squares presented on a touch screen. In each trial the subject had to learn to discriminate and select the correct choice (green) from among a maximum of eight other foils, each varying in either hue or saturation. Relative to unoperated controls, monkeys with middle temporal gyrus lesions were severely impaired in the color discrimination task, whereas monkeys with perirhinal lesions were unimpaired on this task. We also assessed the visual recognition abilities, as measured by a basic delayed nonmatching-to-sample task with trial-unique objects presented in a Wisconsin General Test Apparatus, of rhesus monkeys with bilateral middle temporal gyrus lesions. We then tested the monkeys' postoperative performance on a delayed nonmatching-to-sample task with delays and extended list lengths. The results from this experiment were compared with those from two other groups of rhesus monkeys, an unoperated control group and a group with bilateral perirhinal cortex lesions, both of which had performed the identical tasks in a previous experiment. Relative to unoperated controls, monkeys with perirhinal cortex lesions were severely impaired both in relearning the basic delayed nonmatching-to-sample task and on the postoperative performance test. In contrast, monkeys with middle temporal gyrus lesions were only mildly affected in relearning the basic nonmatching task and were unimpaired on the postoperative performance test. Thus our data demonstrate a clear functional double dissociation between the perirhinal cortex and the middle temporal gyrus. This result gives strong support to the hypothesis that the perirhinal cortex and the adjacent area TE have distinctly different roles in visual learning and memory.

Neural Processing in the Subsecond Time Range in the Temporal Cortex

1998 ◽  
Vol 10 (3) ◽  
pp. 567-595 ◽  
Author(s):  
Kiyohiko Nakamura
Keyword(s):  
Empirical Data ◽  
Cortical Neurons ◽  
Model Simulation ◽  
Temporal Cortex ◽  
Time Range ◽  
Neural Responses ◽  
Neuronal Populations ◽  
Cortical Areas ◽  
Response Onset ◽  
Ventral Pathway

The hypothesis that cortical processing of the millisecond time range is performed by latency competition between the first spikes produced by neuronal populations is analyzed. First, theorems that describe how the mechanism of latency competition works in a model cortex are presented. The model is a sequence of cortical areas, each of which is an array of neuronal populations that laterally inhibit each other. Model neurons are integrate-and-fire neurons. Second, the model is applied to the ventral pathway of the temporal lobe, and neuronal activity of the superior temporal sulcus of the monkey is reproduced with the model pathway. It consists of seven areas: V1, V2/V3, V4, PIT, CIT, AIT, and STPa. Neural activity predicted with the model is compared with empirical data. There are four main results: (1) Neural responses of the area STPa of the model showed the same fast discrimination between stimuli that the corresponding responses of the monkey did: both were significant within 5 ms of the response onset. (2) The hypothesis requires that the response latency of cortical neurons should be shorter for stronger responses. This requirement was verified by both the model simulation and the empirical data. (3) The model reproduced fast discrimination even when spontaneous random firing of 9 Hz was introduced to all the cells. This suggests that the latency competition performed by neuronal populations is robust. (4) After the first few competitions, the mechanism of latency competition always detected the strongest of input activations with different latencies.

Differences in Spiking Patterns Among Cortical Neurons

2003 ◽  
Vol 15 (12) ◽  
pp. 2823-2842 ◽  
Author(s):  
Shigeru Shinomoto ◽  
Keisetsu Shima ◽  
Jun Tanji
Keyword(s):  
Functional Properties ◽  
Cortical Neurons ◽  
Local Variation ◽  
Interspike Intervals ◽  
Cortical Areas ◽  
Spike Sequences ◽  
Spike Sequence

Spike sequences recorded from four cortical areas of an awake behaving monkey were examined to explore characteristics that vary among neurons. We found that a measure of the local variation of interspike intervals, LV, is nearly the same for every spike sequence for any given neuron, while it varies significantly among neurons. The distributions of LV values for neuron ensembles in three of the four areas were found to be distinctly bimodal. Two groups of neurons classified according to the spiking irregularity exhibit different responses to the same stimulus. This suggests that neurons in each area can be classified into different groups possessing unique spiking statistics and corresponding functional properties.

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