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Computations on the Nervous System: Some Results
Published in Theodore B. Achacoso, William S. Yamamoto, AY's Neuroanatomy of C. elegans for Computation, 2022
Theodore B. Achacoso, William S. Yamamoto
A neurologically coherent exemplification of neuronal activity which fits the convolution perspective is that by Cowan, as further developed by Stein et al. These models are membrane, (a + b)T/π. If the two pulse trains Z(a) and Z(b) are added, even if some pulses overlap, the total number of pulses is preserved in any sum over time. Adding the functions before filtering produces (a + b)T/π. The procedure is linear in the average, i.e., the average magnitude of the sum function is the sum of the average magnitudes of the functions. Any linear low-pass filter would also generate the linear magnitude relationship. If time is in any way quantized, the applicable mathematical tools for the single neuron would seem to be that of finite time series, i.e., autoregressive moving average representations [18]. One may conclude that, except for scaling factors, a low-pass filter recovers the average sum. Although, in general, low-pass filters do not recover the signal from frequency modulated form [29], in this case, impulse interval modulation followed by linear filter is a transformation pair that seems to satisfy Heiden’s generalization. Angle modulation as we have defined it, is a transformation of a continuous function in the time domain into a discrete function in the time domain. As interpreters of anatomy, we find this description awkward but hewing more closely to observation, and thus assisting in the quest for a functional neuroanatomy.
Theoretical Paradigms in Cognitive Science and in Theoretical Neurophilosophy
Published in Harald Maurer, Cognitive Science, 2021
In the "weight matrix" or "connectivity matrix"143W, all connection weights of a network are combined. The high connectivity of the neurons is achieved by a large number of weighted connections or links. Like neuroanatomic synapses, these connections have a weighting (or coupling) strength. These weights (modeled by a numerical value) represent either an excitatory or inhibitory influence of a presynaptic neuron on its postsynaptic neuron. Within the context of certain learning rules, it is now possible to learn in an artificial neural network by means of incremental144 synapse modifications by increasing or decreasing particular connection weights.
Brain Motor Centers and Pathways
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
Whereas the preceding chapter was concerned with the lower hierarchical level of the somatomotor system, the present chapter discusses the higher levels of this system. The neuroanatomy and neurophysiology of some of the components of this system have been investigated in considerable detail, and responses of individual neurons or groups of neurons have been correlated with applied stimuli and with behavior. Functions have been ascribed to the various components of the higher levels of the somatomotor system based on a wealth of clinical observations and experimental results, including the effects of genetic modifications in animals. Yet, the manner in which the neuronal structures and properties of a given component bring about the ascribed functions is, in most cases, only poorly understood or has been postulated in rather general terms. This is even more so when it comes to the interactions of the various components of the somatomotor system to produce a given motor action. Hence, the aim of this chapter is to present various aspects of the higher levels of the somatomotor system that are meaningful and relevant to a general understanding of motor performance.
Depressed skull fracture compressing eloquent cortex causing focal neurologic deficits
Published in Brain Injury, 2023
Alexander In, Brittany M. Stopa, Joshua A. Cuoco, Adeolu L. Olasunkanmi, John J. Entwistle
Depressed skull fractures are a cause of traumatic brain injury with an estimated incidence of 44 cases per 100,000 individuals per year (1). The morbidity and mortality of these fractures are notable (1–3). Indeed, a depressed fracture fragment can cause extra-axial hemorrhage, intraparenchymal hemorrhage, violation of the dura, and consequential pneumocephalus (2,3). Moreover, clinical sequelae may develop secondarily, such as seizure activity, cerebrospinal fluid leakage, meningitis, or brain abscess formation (2,3). Rarely, a depressed fracture fragment can cause focal neurologic deficit(s) due to direct compression of the eloquent cortex (4–7). Such cases may be considered an indication for emergent cranioplasty dependent upon the degree of neurologic symptomatology and time to presentation. Here, we present a case of a 40-year-old male who presented to the emergency department after a mechanical fall with the acute onset of several focal neurologic deficits. The neurologic deficits observed on examination were mostly attributed to a depressed skull fracture fragment compressing the underlying eloquent cortex. Our experience highlights a rare indication for emergent cranioplasty with an excellent functional outcome due to immediate fracture elevation and decompression of the eloquent cortex. Moreover, the present case emphasizes the importance of having a keen understanding of functional neuroanatomy.
Intimate partner violence and brain imaging in women: A neuroimaging literature review
Published in Brain Injury, 2023
Jirapat Likitlersuang, David H. Salat, Catherine B. Fortier, Katherine M. Iverson, Kimberly B. Werner, Tara Galovski, Regina E. McGlinchey
A study by Roos et al. (25) expanded analysis on volumetric and cortical thickness structural data using global and regional brain network connectivity measures (structural connectivity) based on structural graph theory. The model creates a brain region (aka hub) that is linked to another brain region based on physical connection (in this case neuroanatomy). This eventually forms a “small world network,” where there are multiple hubs and connection “links,” creating clusters of hubs. The result altered connectivity in the IPV group compared to the control are located at the cognitive-emotional control region of the brain. This includes caudal anterior cingulate, the middle temporal gyrus, left amygdala and ventral diencephalon (including thalamus). However, the association between PTSD and IPV was not reported.
A survey of teaching undergraduate neuroanatomy in the United Kingdom and Ireland
Published in British Journal of Neurosurgery, 2022
Andrew Edwards-Bailey, Howra Ktayen, Georgios Solomou, Emily Bligh, Abbey Boyle, Aref-Ali Gharooni, Guan Hui Tricia Lim, Adithya Varma, Susan Standring, Thomas Santarius, Daniel Fountain
Neuroanatomy provides essential knowledge for medical graduates to manage and understand neurological presentations. As medical schools move towards preparing students for a nationalised assessment of the knowledge, in the form of the MLA, it is important to understand how neuroanatomy teaching is delivered nationally. This understanding may be able to both inform the development of the MLA and identify the educational needs of medical students. We have observed a degree of variability in the amount and method of undergraduate neuroanatomy teaching across the UK and Ireland. Given the comparatively lower levels of confidence seen amongst medical students and junior doctors when it comes to neuroanatomy and clinical neurosciences as a whole, we suggest that there is a role for greater time devoted to neuroanatomical teaching in later years of study in order to improve confidence and levels of competence. Additional teaching initiatives would be best served by promoting the clinical relevance of neuroanatomy to both clinical and pre-clinical students and involving experienced clinicians such as senior neurosurgeons, neurologists and radiologists. These initiatives could then be incorporated more broadly to form a more standardised neuroanatomy undergraduate curriculum, which can be effectively delivered via a diverse range of teaching methods according to the institution and student preference. Moving forwards, methods making use of developing technologies, such as virtual and augmented reality, will likely play an important role in the changing face of undergraduate neuroanatomy teaching.