ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The BARREL CORTEX is a region of SOMATOSENSORY CORTEX in mice and rats that contains discrete groups of multicellular units, or barrel cells, each of which receives innervation from a single hair or VIBRISSAE on the contralateral face. Mechanical stimulation of a single whisker leads to local DEPOLARIZATION of the cells within this unit, which can be detected electrophysiologically. Cortical barrels are arranged topographically, resulting in a SOMATOTOPIC map of vibrissal cortical innervation. These barrels are arranged in columns running throughout the depth of the cortex, and thus receive information from, and send impulses to, other cortical and subcortical structures such as the THALAMUS. Cortical barrels are therefore considered computational units which transform vibrissal information and distribute it to various somatosensory processing areas of the brain. Cortical barrels have been studied extensively because of the ease with which single barrels may be excited through whisker stimulation.
Wheels of Motion: Oscillatory Potentials in the Motor Cortex
Alexa Riehle, Eilon Vaadia in Motor Cortex in Voluntary Movements, 2004
Gamma oscillations have been elicited by stimulation of reticular activating systems.97 In other words, they are associated with high levels of arousal.4,5 During rat exploratory whisking, a burst of gamma oscillation (30-35 Hz) in S1 has been observed to precede the onset of whisking.98 The mean lead time was 268 msec, and the oscillation ceased very soon after the onset of whisking. The gamma rhythm may reflect anticipatory activities in the barrel cortex for the subsequent sensory input from the whiskers.98
Voltage-Sensitive Dye and Intrinsic Signal Optical Imaging
Yu Chen, Babak Kateb in Neurophotonics and Brain Mapping, 2017
VSDi experiments, using a flexible fiber optic image bundle, have been carried out in freely moving mice to visualize neural activity in the barrel cortex while simultaneously filming whisker-related behavior (Ferezou et al., 2006). More recently, VSDi has been used to examine the functional map of the directional sensitivity (Tsytsarev et al., 2010) and gamma oscillations (Khazipov et al. 2013) of the rat barrel cortex.
Combination Effects of Forced Mild Exercise and GABAB Receptor Agonist on Spatial Learning, Memory, and Motor Activity in Striatum Lesion Rats
Published in Journal of Motor Behavior, 2019
Shaghayegh Modaberi, Soomaayeh Heysieattalab, Mehdi Shahbazi, Nasser Naghdi
In a direct pathway, striatum (Str) releases gamma-aminobutyric acid (GABA) neurotransmitter to inhibit GABAergic neurons of the internal Globus Pallidus (GPi) which projects GABAergic outputs to many nuclei of the BG including Str, STN, entopeduncular nucleus, and substantia nigra (SN) (Bevan, Booth, Eaton, & Bolam, 1998; Hazrati, Parent, Mitchell, & Haber, 1990; Kita, 1994; Kita & Kita, 1994, 2001). In indirect pathways, cortical activation results in the activation of the GABAergic striatum, followed by enhanced inhibition of GABAergic neurons in the Globus Pallidus external (GPe). Therefore, a direct pathway excites thalamus while an indirect one results in inhibition of thalamic activity (Galvan, Devergnas, & Wichmann, 2015). Block, Kunkel, and Schwarz (1993) showed that injection of quinolinic acid (QA) into the striatum of rats induced deficits in spatial learning and motor performance similar to those observed in Huntington's disease (Block et al., 1993). However, Lee et al. (2011) investigated sensory processing in the barrel cortex neurons of an animal model of Alzheimer’s disease (AD) by infusion of ibotenic acid (IA) into nucleus basalis of Meynert (NBM). They showed that IA infusion into NBM significantly reduced memory and sensory processing, and contact discrimination in AD animals (Goshadrou, 2011). Several studies have described that lesions of GP alone or in combination with SN cause motor activity deficits (Mink, 1996). Output of both direct and indirect pathways through GPi and SNr, projects to the thalamus and brainstem (Walter & Vitek, 2012). GABAB receptors are involved in the modulation of GABAergic transmission in the GPe and GPi. It is possible that changes in the function or localization of these receptors contribute to the alterations of GABAergic transmission (Galvan, Hu, Smith, & Wichmann, 2011). Previous studies suggested that GABAB receptor in the GP plays an important role in the regulation of movement by modulating of GABAergic inputs at a presynaptic site (Chen, Chan, & Yung, 2002) and microinjection of Baclofen in the GPe and GPi leads to a significant increase in the proportion of spikes in parkinsonian animals (Galvan et al., 2011). So, striatum dysfunction disturbs inhibitory inputs to the GPi and other nuclei. In addition, human’s research indicated Baclofen to be an effective treatment for spasticity in cerebral palsy, dystonia, and other various movement disorders (Kraus et al., 2017). However, studies showed that GABAergic transmission in BG has an effective role in memory processes. For example, post-training infusions of the GABA receptor antagonist picrotoxin into the SN and dorsal striatum impairs memory (Kim & Routtenberg, 1976; Salado-Castillo, del Guante, Alvarado, Quirarte, & Prado-Alcalá, 1996).
Related Knowledge Centers
- Cortical Column
- Cytochrome C Oxidase
- Somatosensory System
- Synaptic Plasticity
- Trigeminal Nerve
- Thalamus
- Whiskers
- Topographic Map
- Trigeminal Nerve Nuclei
- Secondary Somatosensory Cortex