Perception and cognition require the integration of feedforward sensory information with feedback signals. Using different sized stimuli, we isolate spectral signatures of feedforward and feedback signals, and their effect on communication between layers in primary visual cortex of male macaque monkeys. Small stimuli elicited gamma frequency oscillations predominantly in the superficial layers. These Granger-causally originated in upper layer 4 and lower supragranular layers. Unexpectedly, large stimuli generated strong narrow band gamma oscillatory activity across cortical layers. They Granger-causally arose in layer 5, were conveyed through layer six to superficial layers, and violated existing models of feedback spectral signatures. Equally surprising, with large stimuli, alpha band oscillatory activity arose predominantly in granular and supragranular layers and communicated in a feedforward direction. Thus, oscillations in specific frequency bands are dynamically modulated to serve feedback and feedforward communication and are not restricted to specific cortical layers in V1.
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http://dx.doi.org/10.7554/eLife.62949 | DOI Listing |
Neuroscience
December 2024
Department of Psychology, Concordia University, Montreal, Canada. Electronic address:
Estrogens and progesterone can have rapid effects on neuronal function and can modify the use of spatial navigation strategies dependent upon the prefrontal cortex, striatum, and hippocampus. Here, we assessed the effects of 17β-estradiol (E2), progesterone, and its metabolite allopregnanolone, on evoked excitatory postsynaptic potentials in the infralimbic region of the female rat prefrontal cortex. Field excitatory postsynaptic potentials (fEPSPs) evoked by stimulation of layer I were first characterized by recording responses at multiple depths between the cortical surface and the underlying white matter.
View Article and Find Full Text PDFEpilepsia
December 2024
Department of Neurology, University of Virginia, Charlottesville, Virginia, USA.
Objective: Focal cortical seizures travel long distances from the onset zone, but the long-distance propagation pathways are uncertain. In vitro and in vivo imaging techniques have investigated the local spread of seizures but did not elucidate long-distance spread. Furthermore, classical studies in slices suggested seizure spread locally along deep cortical layers, whereas more recent in vivo imaging studies posit a role for superficial cortical layers in local spread.
View Article and Find Full Text PDFPLoS One
December 2024
School of Biomedical Sciences, Monash University, Melbourne, Victoria, Australia.
A central topic in neuroscience is the neural coding problem which aims to decipher how the brain signals sensory information through neural activity. Despite significant advancements in this area, the characterisation of information encoding through the precise timing of spikes in the somatosensory cortex is limited. Here, we utilised a comprehensive dataset from previous studies to identify and characterise temporal response patterns of Layer 4 neurons of the rat barrel cortex to five distinct stimuli with varying complexities: Basic, Contact, Whisking, Rough, and Smooth.
View Article and Find Full Text PDFAlzheimers Dement
December 2024
Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA.
Introduction: We investigated whether the cerebellum develops neuropathology that correlates with well-accepted Alzheimer's disease (AD) neuropathological markers and cognitive status.
Methods: We studied cerebellar cytoarchitecture in a cohort (N = 30) of brain donors. In a larger cohort (N = 605), we queried whether the weight of the contents of the posterior fossa (PF), which contains primarily cerebellum, correlated with dementia status.
Brain Stimul
December 2024
Department of Electrical and Computer Eng., Worcester Polytechnic Inst., Worcester MA USA; Department of Mathematical Sciences, Worcester Polytechnic Inst., Worcester MA USA.
Background: Modeling brain stimulation at the microscopic scale may reveal new paradigms for various stimulation modalities.
Objective: We present the largest map to date of extracellular electric field distributions within a layer L2/L3 mouse primary visual cortex brain sample. This was enabled by the automated analysis of serial section electron microscopy images with improved handling of image defects, covering a volume of 250 × 140 × 90 μm³.
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