The pulvinar is the largest extrageniculate thalamic visual nucleus in mammals. It establishes reciprocal connections with virtually all visual cortexes and likely plays a role in transthalamic cortico-cortical communication. In cats, the lateral posterior nucleus (LP) of the LP-pulvinar complex can be subdivided in two subregions, the lateral (LPl) and medial (LPm) parts, which receive a predo...

Visual information is mediated by two major thalamic pathways that signal light decrements (OFF) and increments (ON) in visual scenes, the OFF pathway being faster than the ON. Here, we demonstrate that this OFF temporal advantage is transferred to visual cortex and has a correlate in human perception. OFF-dominated cortical neurons in cats responded ∼3 ms faster to visual stimuli than ON-domin...

In primary visual cortex (V1), connectivity between layer 2/3 (L2/3) excitatory neurons undergoes extensive reorganization after the onset of visual experience whereby neurons with similar feature selectivity form functional microcircuits (Ko et al., 2011, 2013). It remains unknown whether visual experience is required for the developmental refinement of intracortical circuitry or whether this ...

Circadian rhythms in mammals are controlled by the neurons located in the suprachiasmatic nucleus of the hypothalamus. In physiological conditions, the system of neurons is very efficiently entrained by the 24 h light-dark cycle. Most of the studies carried out so far emphasize the crucial role of the periodicity imposed by the light-dark cycle in neuronal synchronization. Nevertheless, heterog...

Introduction: Repetitive cortical spreading depression (CSD) can lead to cell death in immature brain tissue. Caspases are involved in neuronal cell death in several CSD-related neurological disorders. Yet, whether repetitive CSD itself can induce caspase activation in adult or juvenile tissue remains unknown. Inducing repetitive CSD in somatosensory cortices of juvenile and adult rats in vivo,...

The fundamental function of the nervous system is to accurately process and respond to external stimuli. This issue's Neurobiology Select highlights recent findings exploring how neurons and their networks within the nervous system may be modulated to ensure accurate signal detection, transmission, and response. In larvae of the frog Xenopus laevis, light regulates a neural circuit in the ventr...

Some neurochemical responses of dopaminergic neurons in the rabbit retina have been measured during prolonged light or dark adaptation. Light adaptation produced small increases (20%) in dopamine levels but larger increases (50-100%) in the two metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid. Light also significantly increased tyrosine hydroxylase activity; the increase was mo...

The mushroom body (MB) is a higher center of the insect brain and is critical to olfactory and other forms of associative memory. Here, we report that repetitive modular subunits, which we refer to as slabs, are present in the internal matrix of the alpha lobe, a major output neuropil of the MB in the cockroach. The methods employed were osmium-ethyl gallate, Bodian-reduced silver, and Golgi st...