Table of Contents
Annotations
(14/10/2023, 07:20:54 )
Organization of Claustrum similar to Thalamus
“Based on the widespread connectivity of claustrum with cortex, and the zones of cortical targeting in the claustrum, it appears that the organization of the claustrum resembles that of the thalamus (Olson and Graybiel, 1980)” (Mathur, 2014, p. 5)
CLA connections: projections into dorsal thalamus, Striatum, Hypothalamus
“Studies in the hedgehog, rat, cat, tree shrew, and macaque have reported claustral projections to the dorsal thalamic nuclei (LeVay and Sherk, 1981; Carey and Neal, 1986; Dinopoulos et al., 1992; Erickson et al., 2004; McKenna and Vertes, 2004; Vertes and Hoover, 2008), striatum (Arikuni and Kubota, 1985), hippocampus (Amaral and Cowan, 1980), and hypothalamus (LeVay and Sherk, 1981; Vertes, 1992; Yoshida et al., 2006).” (Mathur, 2014, p. 5)
CLA connections: “reicprocally connected with all cortical sites”
“Today it is generally accepted that the claustrum is reciprocally connected with all cortical sites (Sherk, 1986)” (Mathur, 2014, p. 4)
CLA connections: somewhat surrounded by insular cortex
“The pattern of purkinje cell protein 4 mRNA expression and retrograde labeling throughout the insula further supports that the claustrum is surrounded by insular cortex, rather than being arranged into “core” and “shell” subcomponents that have differential connectivity.” (Mathur, 2014, p. 6)
CLA connections: reciprocal connections mainly to cortex; probably less projections to subcortical sites
“the claustrum appears to connect (reciprocally) to cortex, and not to project to other prominent subcortical sites (lateral hypothalamus and mediodorsal nucleus of the thalamus) as once thought (Mathur et al., 2009). However, afferent connections from subcortical sites such as the dorsal raphe nucleus remain a possibility.” (Mathur, 2014, p. 9)
CLA function: rare knowledge of claustrum function
“The final, and most puzzling, “problem” of the claustrum lies in its function. Relative to other prominent telencephalic structures such as the cortex, striatum, and thalamus, knowledge of claustral function is sorely lacking.” (Mathur, 2014, p. 6)
Due to shape, CLA lesions difficult to achieve
“The shape of the claustrum has made complete and discrete claustrum lesions impossible to achieve using conventional chemical or mechanical means.” (Mathur, 2014, p. 6)
CLA sensory integration: apparently evidence for multisensory integration was found
“Based on its bidirectional cortical connectivity, the claustrum has been proposed to function as a multisensory integrator; serving to bind information from disparate sensory cortices. Supporting this notion, Segundo and Machne (1956) and later Spector et al. (1974) found electrophysiological evidence for sensory convergence in the claustrum” (Mathur, 2014, p. 6)
Most common CLA sensory integration observed somatoolfactory, somato-visceral, and somato-nocioceptive
“The most common convergences observed were somatoolfactory, somato-visceral, and somato-nocioceptive (Segundo and Machne, 1956).” (Mathur, 2014, p. 7)
CLA oscillation synchronization: proposal that claustrum synchronizes cortical activity (Ettlinger & Wilson 1990)
“Ettlinger and Wilson (1990), states that no one structure in brain executes the processes required for cross-modal performance. Instead, only a subcortical relay nucleus is required through which different sensory cortices can access each other in order to associate modalities. This subcortical relay nucleus was proposed to be the claustrum. In this way, the claustrum theoretically synchronizes cortical areas to accomplish the feat of crossing modalities” (Mathur, 2014, p. 7)
CLA divided into sensory zones
“the claustrum is subdivided into discrete sensory zones. That is, the visual zone of the claustrum preferentially and transiently responds to suddenly presented visual cues, while the auditory subdivision of the claustrum does the same for auditory cues (Remedios et al., 2010)” (Mathur, 2014, p. 7)
Problem: discriminate between claustral vs. insular activation
“The imaging studies that do support a role for the claustrum in multisensory integration do not address the question of where polymodal information is being bound exactly, and again suffer from the inability to discriminate between claustral vs. insular activation” (Mathur, 2014, p. 7)
[[Crick & Koch, 2005]]
“Crick and Koch (2005) hypothesized that the claustrum is where sensory information is bound, functioning as a generator of the unified perception of a multitude of sensory stimuli in one’s environment (conscious percepts)” (Mathur, 2014, p. 7)
“This hypothesis has received further theoretical support from Smythies et al. (2012), who propose that the claustrum functions as a detector, modulator, and integrator of synchronous oscillations for the purpose of subserving cognitive processes such as consciousness.” (Mathur, 2014, p. 7)
CLA salience: role leaning towards higher order association ares than only sensory areas
“The saliency detection concept fits with existing structural and functional data and presents testable predictions. The first prediction is that the claustrum is most intimately connected to higher order association cortices, rather than primary sensory cortices.” (Mathur, 2014, p. 8)
CLA salience: focus may be on detecting new stimuli
“As novel stimuli are often perceived as salient, the claustrum may also be involved in attentional allocation to cortical sites signaling to the striatal complex during the learning of novel actions” (Mathur, 2014, p. 9)
“It is clear that a consensus on the structural boundaries of the claustrum is required.” (Mathur, 2014, p. 9)
- Gibt es mittlerweile einen Konsensus?
“It is also possible that a cingulate cortex-to-claustrum-to-sensorimotor cortex/association cortex circuit may be recruited for allocation of attentional load to the necessary cortical sites demanded of a particularly salient stimulus. These hypotheses could possibly be tested using optogenetic activation/inactivation of cingulate fibers projecting to the claustrum during a modified 5-choice reaction test in rodents.” (Mathur, 2014, p. 8)