Sensory cortical neurons are highly sensitive to brain state, with many showing changes in spatial and/or temporal response properties and some becoming virtually unresponsive when subjects not alert. Although of these undoubtedly attributable state-related filtering at the thalamic level, another likely source such effects is thalamocortical (TC) synapse, where activation nicotinic receptors on TC terminals have been shown enhance synaptic transmission vitro . However, monosynaptic has...

Thalamocortical conduction times are short, but layer 6 corticothalamic axons display an enormous range of times, some exceeding 40–50 ms. Here, we investigate (1) how axonal corticogeniculate (CG) neurons related to the visual information conveyed thalamus, and (2) alert versus nonalert awake brain states affect processing across spectrum CG times. In female Dutch-Belted rabbits, found 58% be visually responsive, 42% unresponsive. All responsive had simple, orientation-selective receptive...

The effects of different EEG brain states on spontaneous firing cortical populations are not well understood. Such state shifts may occur frequently under natural conditions, and baseline patterns can impact neural coding (e.g., signal-to-noise ratios, sparseness coding). Here, we examine the transitions from alert to nonalert awake in rabbit visual cortex (5 s before after state-shifts). In layer 4, examined putative spiny neurons fast-spike GABAergic interneurons; 5, corticotectal neurons....

Extracellular recordings were obtained from two cell classes in layer 4 of the awake rabbit primary visual cortex (V1): putative inhibitory interneurons [suspected (SINs)] and excitatory cells with simple receptive fields. SINs identified solely by their characteristic response to electrical stimulation lateral geniculate nucleus (LGN, 3+ spikes at >600 Hz), field structure, requiring spatially separate ON and/or OFF subfields. Notably, no met both criteria, we studied 62 33 SINs....

We used spike-triggered current source-density analysis to examine axonal and postsynaptic currents generated in the visual cortex of awake rabbits by spontaneous spikes individual sustained transient dorsal lateral geniculate nucleus (LGNd) neurons. Using these data, we asked whether sustained/transient sensory responses are related short-term synaptic dynamics at thalamocortical synapse. Most (34 40) (24 25) neurons monosynaptic layer 4 and/or 6 aligned cortical domain, with input from...

Arrays of closely spaced quartz-insulated, platinum-tungsten microelectrodes are widely used to obtain acute recordings from chronically prepared subjects. These electrodes have excellent recording characteristics and can be fabricated a wide variety tip specifications. Typically, in such experiments, introduced into, removed from, the brain on daily basis and, over many months study, hundreds penetrations may made through an intact dura. This procedure has benefits as well problems risks....

The spread of somatic spikes into dendritic trees has become central to models integrative properties and synaptic plasticity. However, backpropagating action potentials (BPAPs) have been studied mainly in slices, which they are highly sensitive multiple factors such as firing frequency membrane conductance, raising doubts about their effectiveness the awake behaving brain. Here, we examine spatiotemporal characteristics BPAPs layer 5 pyramidal neurons visual cortex adult, rabbits,...

Associative Hebbian-type synaptic plasticity underlies the mechanisms of learning and memory; however, Hebbian rules lead to runaway dynamics weights lack for competition.Heterosynaptic may solve these problems by complementing at synapses that were active during induction, with opposite-sign changes non-activated synapses. In visual cortex, a potential candidate mechanism normalization is induced purely postsynaptic protocol, intracellular tetanization. Here we asked if tetanization can...

Directionally selective (DS) neurons are found in the retina and lateral geniculate nucleus (LGN) of rabbits rodents, rabbits, LGN DS cells project to primary visual cortex. Here, we compare response properties with those layer 4 simple cells, most which show strong direction/orientation selectivity. These populations differed dramatically, suggesting that may not contribute significantly synthesis receptive fields: 1) whereas first harmonic component (F1)-to-mean firing rate (F0) ratios...

Awake mammals can switch between alert and nonalert brain states hundreds of times per day. Here, we study the effects alertness on two cell classes in layer 4 primary visual cortex awake rabbits: presumptive excitatory “simple” cells fast-spike inhibitory neurons (suspected interneurons). We show that both classes, increases strength greatly enhances reliability responses. In simple cells, also temporal frequency bandwidth, but preserves contrast sensitivity, orientation tuning, selectivity...

Information transmission in neural networks is influenced by both short-term synaptic plasticity (STP) as well nonsynaptic factors, such after-hyperpolarization currents and changes excitability. Although these effects have been widely characterized vitro using intracellular recordings, how they interact vivo unclear. Here, we develop a statistical model of the dynamics spike that aims to disentangle contributions based only on observed presynaptic postsynaptic spiking. The includes dynamic...

Each point in visual space is encoded at the level of thalamus by a group neighboring cells with overlapping receptive fields. Here we show that fields these differ size and response latency but not random. We have found cat lateral geniculate nucleus (LGN) field neurons are significantly correlated: larger field, faster to stimuli. This correlation widespread LGN. It groups belonging same type (e.g., Y cells), different types (i.e., X Y), within specific layer or across layers. These...

The neuronal connections from the retina to dorsal lateral geniculate nucleus (dLGN) are characterized by a high specificity. Each retinal ganglion cell diverges connect small group of cells and each receives input number cells. Consistent with specificity connections, sharing same afferent thought have very similar receptive fields. However, magnitude receptive-field mismatches, which has not been systematically measured across different types in dLGN, seems be contradiction functional...

The retinas of rabbits and rodents have directionally selective (DS) retinal ganglion cells that convey directional signals through the lateral geniculate nucleus (LGN) thalamus to primary visual cortex (V1). Notably, function synaptic impact in V1 these LGN are unknown. Here we measured, awake rabbits, generated by individual DS neurons. We show neurons make fast strong connections layers 4 6, with postsynaptic effects similar those made concentric neurons, main thalamic drivers V1. By...

Abstract Background The daily peak in dopaminergic neuronal activity at the area of biological clock (hypothalamic suprachiasmatic nuclei [SCN]) is diminished obese/insulin resistant vs lean/insulin sensitive animals. impact targeted lesioning dopamine (DA) neurons specifically surrounding (and that communicate with) SCN (but not within itself) upon glucose metabolism, adipose and liver lipid gene expression, cardiovascular biology normal laboratory animals has been investigated was focus...

Corticotectal (CTect) neurons of layer 5 are large and prominent elements mammalian visual cortex, with thick apical dendrites that ascend to 1, “intrinsically bursting” membrane properties, fast-conducting descending axons terminate in multiple subcortical domains. These comprise a major output pathway primary but virtually nothing is known about the synaptic influence single CTect impulses on superior colliculus (SC). Here, we examine distribution monosynaptic currents generated...

The Y pathway in the cat visual system is traditionally viewed as a single channel that originates retina. However, most cells from contralateral retina diverge to innervate two different layers of lateral geniculate nucleus, suggesting possible split: C (Y cell layer C) and A A). We tested functional significance this anatomical divergence by comparing response properties simultaneously recorded with overlapping receptive fields. Our results demonstrate significantly differ large number...

Sensory adaptation serves to adjust awake brains changing environments on different time scales. However, has been studied traditionally under anesthesia and for short periods. Here, we demonstrate in rabbits a novel type of sensory that persists >1 h acts visual thalamocortical neurons their synapses the input layers cortex. Following prolonged stimulation (10-30 min), cells dorsal lateral geniculate nucleus (LGN) show severe reduction spontaneous firing rate. This effect is bidirectional,...

Abstract Introduction Within the ventromedial hypothalamus (VMH), glucose inhibitory (GI) neurons sense hypoglycaemia while excitatory (GE) hyperglycaemia to initiate counter control mechanisms under normal conditions. However, potential electrophysiological alterations of these two neuronal types in vivo insulin‐resistant states have never been simultaneously fully documented. Further, anti‐diabetic effect dopamine agonism on this VMH system insulin resistance has not studied. Methods This...