"Theta waves appear to be an invaluable key to the understanding of associative processing capacities of the human central nervous system."
"In a comprehensive review Klimesch (1996) stressed the implications for a more anteriorly organized (limbic) theta system, functionally linked to tasks involving episodic memory, and a posterior (thalamic) alpha-system modulated by long term memory tasks. His experimental findings support the following hypothesis: short term (episodic) memory demands lead to synchronization in the theta band manifested in an increase in band power. However, long-term (semantic) memory demands lead to a task specific desynchronization in the upper alpha band (decrease of power). Oscillations in these frequency bands possibly provide the basis for encoding, accessing and retrieving cortical codes that are stored in form of widely distributed but intensively interconnected cell assemblies. Investigations of our own group also lead to the conclusion that these distinct frequency-bands are attributable to various brain functions (Basar and Schurmann, 1994; Schurmann and Basar, 1994). The fact that alpha and theta band-power change upon tasks with a cognitive load in a reciprocal way, lead to the idea that functions like sensory processing and cognitive processing might be represented by `preferred frequencies' (Basar, 1992).
(...) Previous results led us to postulate the existence of a selectively distributed theta-response system in the brain (Basar et al., 1992; Basar, 1998, 1999). We tentatively assumed that the theta component of the evoked potentials and/or slower responses might reflect the responsiveness of various brain areas involved with global associative-cognitive performance."
In patients who experienced a stroke, it appears that mental imagery training was able to enhance task analysis
"Further analysis of other ability measures administered to patients in this study reveals that the relearning may be attributed to the improved attention and sequencing-processing abilities of patients who underwent mental imagery training, which is indicated by their improved CTT subscale scores. Improved attention is associated with improved planning and execution of task performance. Improved sequential processing is associated with the generation of images depicting each step of the daily tasks. Such behavioral observation is also confirmed by the results of other studies that used radiologic imaging techniques. Parson et al used positron emission tomography scans to demonstrate the activation of the prefrontal, parietal, and cerebellar regions of the brain during mental imagery tasks. Functionally, these activations refer to enhanced attention and working memory and a higher level of processing ability."
The caudal thalamic reticular nucleus may be specifically concerned with how stimulation is dealt with (e.g. analysis enhancement)
"The thalamic reticular nucleus (TRN), and especially its caudal, sensory related, half (cTRN), has been hypothesised for years to be at the very heart of thalamic sensory processing modulation, and attentional processes in particular.
(...) 6.7. Conclusion Combined, the results of our four investigations suggest that despite being implicated in attentional processes (e.g. chapter II) cTRN may not be involved in the generation of certain attentional behaviours such as the cross-modal division of attention (chapter III) and the endogenous and exogenous movement of visuospatial attention (chapters IV and V). Instead, our findings suggest that cTRN’s role may be more specifically concerned with how certain forms of stimulation are dealt with, within these forms of attentional behaviour (e.g. detection or analysis enhancement). Overall, therefore, and despite the absence of major attentional deficits following its destruction, our results do not rule out the involvement of cTRN in what are broadly labelled “attentional processes”. Given the multiple facets of attention, cTRN’s role may be limited to specific aspects of only some of these processes. A more detailed delineation of its functional anatomy and the electrophysiological relationship with its afferents and efferents would aid the identification of these attentional aspects and guide the search for the exact attentional mechanisms, if any, for which cTRN is responsible."
Attention is the bottleneck
"In general terms, attentional abilities form the most crucial 'bottleneck' in the cognitive capabilities and determine a subject's ability to adapt, learn, and remember information, and possibly to experience consciousness [1-10,57,65]. Thus, alterations in attentional functions, if persistent, globally and devastatingly affect a subject's cognitive status [61,72]. It is speculated, therefore, that drug-induced enhancement of attentional abilities in the long-term is capable of significantly improving a subject's general cognitive status."
- Sakowitz, O. W., Schürmann, M., & Başar, E. (2000). Oscillatory frontal theta responses are increased upon bisensory stimulation. Clinical Neurophysiology, 111(5), 884-893. https://doi.org/10.1016/S1388-2457(99)00315-6
- Liu, K. P., Chan, C. C., Lee, T. M., & Hui-Chan, C. W. (2004). Mental imagery for promoting relearning for people after stroke: A randomized controlled trial. Archives of physical medicine and rehabilitation, 85(9), 1403-1408. https://doi.org/10.1016/j.apmr.2003.12.035
- Petrof, I. (2007). Behavioural analysis of the role of caudal thalamic reticular nucleus in attention (Doctoral dissertation, University of St Andrews). http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.127.2158&rep=rep1&type=pdf
- Sarter, M., & Bruno, J. P. (1997). Trans-synaptic stimulation of cortical acetylcholine and enhancement of attentional functions: a rational approach for the development of cognition enhancers. Behavioural brain research, 83(1-2), 7-14. https://doi.org/10.1016/S0166-4328(97)86039-1