Sherman, S. M. Tonic and burst firing: dual modes of thalamocortical relay. Trends Neurosci. 24, 122-126

Department of Neurobiology, State University of New York, Stony Brook, New York, NY 11794-5230, USA.
Trends in Neurosciences (Impact Factor: 13.56). 03/2001; 24(2):122-6. DOI: 10.1016/S0166-2236(00)01714-8
Source: PubMed


All thalamic relay cells exhibit two distinct response modes--tonic and burst--that reflect the status of a voltage-dependent, intrinsic membrane conductance. Both response modes efficiently relay information to the cortex in behaving animals, but have markedly different consequences for information processing. The lateral geniculate nucleus, which is the thalamic relay of retinal information to cortex, provides a reasonable model for all of thalamus. Compared with burst mode, geniculate relay cells that are firing in tonic mode exhibit better linear summation, but have poorer detectability for visual stimuli. The switch between the response modes can be controlled by nonretinal, modulatory afferents to these cells, such as the feedback pathway from cortex. This allows the thalamus to provide a dynamic relay that affects the nature and format of information that reaches the cortex.

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    • ", 2002 ) . When coding for comparable signals , bursts , in comparison with single spikes , have been shown to improve the SNR ratio ( Sherman , 2001 ) and are suggested to improve information transfer between neurons ( Lisman , 1997 ) . "
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    ABSTRACT: To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g. in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g. in auditory delay lines). Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs) that transfer information from the primary olfactory centers, the antennal lobe (AL), to a multimodal integration center, the mushroom body (MB). PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code).
    Frontiers in Physiology 07/2015; 6(208). DOI:10.3389/fphys.2015.00208 · 3.53 Impact Factor
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    • "However, combined application of Ino with muscimol, bicuculline and theophylline (Fig. 4B, D, F) suggests that absence epileptic activity increasing effect of Ino results mainly from the increase of inhibitory tone via thalamic GABA A receptors and/or by thalamic A 2A receptors evoked increase in GABAergic functions in WAG/Rij rats. In relation to Ino-evoked effects on absence epileptic activity, it is interesting to note that the excitatory tone increasing GABAergic antagonists and Ado receptor antagonists decreased absence epileptic activity (Peeters et al., 1989; Ates et al., 2004) whereas absence epileptic activity aggravated by increasing the inhibitory tone by Ado, GABAergic agonists and GABA reuptake blockers (Peeters et al., 1989; Coenen et al., 1995; Ilbay et al., 2001) probably because membrane hyperpolarization in thalamic relay neurons is necessary to evoke SWDs via burst firing mode (Sherman, 2001; Cope et al., 2009; Crunelli et al., 2012). In addition, augmented thalamic (relay nuclei) GABA A receptor subunit (a 4 and d) expression evoked increase in tonic inhibition of thalamic neurons may be in relation to the exacerbation of absence epileptic seizures in symptomatic WAG/Rij rats (Pisu et al., 2008). "
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    ABSTRACT: Adenosine (Ado) and non-adenosine (non-Ado) nucleosides such as inosine (Ino), guanosine (Guo) and uridine (Urd) may have regionally different roles in the regulation of physiological and pathophysiological processes in the central nervous system (CNS) such as epilepsy. It was demonstrated previously that Ino and Guo decreased quinolinic acid (QA)-induced seizures and Urd reduced penicillin-, bicuculline- and pentylenetetrazole (PTZ) -induced seizures. It has also been demonstrated that Ino and Urd may exert their effects through GABAergic system by altering the function of GABAA receptors whereas Guo decreases glutamate-induced excitability through glutamatergic system, which systems (GABAergic and glutamatergic) are involved in pathomechanisms of absence epilepsy. Thus, we hypothesized that Ino and Guo, similarly to the previously described effect of Urd, might also decrease absence epileptic activity. We investigated in the present study whether intraperitoneal (i.p.) application of Ino (500 and 1000 mg/kg), Guo (20 and 50 mg/kg), Urd (500 and 1000 mg/kg), GABAA receptor agonist muscimol (1 and 3 mg/kg), GABAA receptor antagonist bicuculline (2 and 4 mg/kg), non-selective Ado receptor antagonist theophylline (5 and 10 mg/kg) and non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist (+)-5-methyl-10,11-dihydro-5H-dibenzo (a,d) cyclohepten-5,10-imine maleate (MK-801, 0.0625 and 0.1250 mg/kg) alone and in combination have modulatory effects on absence epileptic activity in Wistar Albino Glaxo Rijswijk (WAG/Rij) rats. We found that Guo decreased the number of spike-wave discharges (SWDs) whereas Ino increased it dose-dependently. We strengthened that Urd can decrease absence epileptic activity. Our results suggest that Guo, Urd and their analogues could be potentially effective drugs for treatment of human absence epilepsy. Copyright © 2015. Published by Elsevier Ltd.
    Neuroscience 05/2015; 300. DOI:10.1016/j.neuroscience.2015.05.054 · 3.36 Impact Factor
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    • "Each sector of the TRN receives projections from corresponding cortical and thalamic neurones and projects back to the thalamic nucleus which innervates it. The thalamic nuclei have been classed as 'first' or 'higher' order (Sherman, 2001). Afferents to these nuclei arise from a range of sources and are classed as 'drivers' (Class 1) or 'modulators' (Class 2). "
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    ABSTRACT: The thalamus (comprising many distinct nuclei) plays a key role in facilitating sensory discrimination and cognitive processes through connections with the cortex. Impaired thalamocortical processing has long been considered to be involved in schizophrenia. In this review we focus on the thalamic reticular nucleus (TRN) providing evidence for it being an important communication hub between the thalamus and cortex and how it may play a key role in the pathophysiology of schizophrenia. We first highlight the functional neuroanatomy, neurotransmitter localisation and physiology of the TRN. We then present evidence of the physiological roles of the TRN in relation to oscillatory activity, cognition and behaviour. Next we discuss the role of the TRN in rodent models of risk factors for schizophrenia (genetic and pharmacological) and provide evidence for TRN deficits in schizophrenia. Finally we discuss new drug targets for schizophrenia in relation to restoring TRN circuitry dysfunction. © The Author(s) 2015.
    Journal of Psychopharmacology 01/2015; 29(2). DOI:10.1177/0269881114565805 · 3.59 Impact Factor
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