Is the Motor Cortex Only an Executive Area? Its Role in Motor Cognition
Alexa Riehle, Eilon Vaadia in Motor Cortex in Voluntary Movements, 2004
The simulation hypothesis is a rather broad framework accounting for the relationship of mental phenomena to the activity of the neural substrate. Its empirical basis accumulated from experiments in cognitive neuroscience in the past two decades. One of the most influential results showed that visual mental images rely on activation of the early stages of information processing of the visual system. The primary visual cortex (V1) is consistently involved in visual mental imagery,5253 with an additional selective involvement of the inferotemporal cortex during imagery of visual objects and of the occipitoparietal cortex in visual spatial imagery. The explanation put forward for an activation of low-level processing areas during a high-level cognitive activity is that activation of topographically organized areas, such as V1, is needed for replacing the image within a spatial frame of reference. Higher-order areas, because they lack topographical organization, would not be able, by themselves, to achieve this task. In other words, the processing of visual imagery would have to follow the same processing track as visual perception for giving an image its spatial layout, a process that requires the participation of V1.
ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
The visual system is the part of the BRAIN that receives information from the eyes and processes that information to facilitate actions and decisions. The information received and processed can be used to control directly undertaken actions, such as walking or grasping an object, but can also be used to facilitate the planning of future actions. The first stage of the visual system is to be found in the EYE itself. An image of the scene is focused by the lens of the eye on to the RETINA, the layer of photosensitive cells or receptors which lines the back of the eye. The light causes a pattern of electrical activity in the receptor cells. This pattern is converted into a pattern of neuronal impulses at the stage of the retinal ganglion cells. These cells send axons up the OPTIC NERVE and into the brain proper. The information first gets processed at the LATERAL GENICULATE NUCLEUS (LGN) and is then passed on to the VISUAL CORTEX. These early stages of the visual system are generally concerned with ensuring that the best quality of information is recovered from the image as possible. For example, the range of luminances in a scene can be extremely high—much beyond the capacity of the bandwidth of the visual system. Some parts of the image are very dim and the luminance differences are very small, but at the same time, other parts of the image can be very bright and have relatively large luminance differences. The early stages of the visual system are concerned with making sure that, whatever the local image luminance is, the important contrast information is re-ceived at the visual cortex, where the bulk of the visual processing occurs.
Stress, Perceptual Distortions, and Human Performance
Darrell L. Ross, Gary M. Vilke in Guidelines for Investigating Officer-Involved Shootings, Arrest-Related Deaths, and Deaths in Custody, 2018
The limbic system is responsible for the functions of arousal, emotions, and memories. It deals with high and low functions and is found in the brain stem within the cerebrum. The major components include the thalamus, hypothalamus, amygdala, hippocampus, and basal ganglia. The thalamus lies deep inside the brain and is responsible for several functions. With the exception of smell, the thalamus serves to pick up sensory and motor stimuli and relays it to other portions of the brain, while regulating sleep and consciousness. The thalamus is associated with the visual system, receiving input from the retina and then transmitting information through the optic nerve and onto the occipital lobe. It is involved in sensory perception and movement.
Impact of Alzheimer’s Disease in Ocular Motility and Visual Perception: A Narrative Review
Published in Seminars in Ophthalmology, 2022
AD is characterised by the accumulation of amyloid-Aℬ proteins and hyperphosphorylated Tau and neuronal loss, causing progressive posterior cortical atrophy and cognitive impairment. The most studied oculomotor manifestations are deficiencies in the saccades that are correlated with reductions in cortical thickness.13–15,19,25,26,28–31,36,38,39,41,44,45,66,67,72,74,75,80 Various studies have shown that these ocular alterations can be considered as markers of AD in early stages and a criterion for characterizing the progression of the disease.13–15,19,25,26,28–31,36,38,39,41,44,45,66,67,72,74,75,80 Besides alterations in ocular motility, different alterations in visual perception have been reported in patients with AD that are summarized in Table 3. All these alterations can be explained by the cerebral disorders occurring in AD. It should be noted that the central nervous system shares vascular and cellular components with the visual system.16 For this reason, disorders in ocular motility and visual perception may be important biomarkers for an early diagnosis of AD. These biomarkers could be combined with retinal biomarkers to develop more consistent and reliable criteria for early detection of AD. However, the diagnostic ability of oculomotor and visual variables for the detection of AD has not been directly evaluated, with no clear definition of specific cut-off points to this date. More research is needed on this issue to define clinical protocols in visual assessment helping in the early diagnosis of AD.
Functional and anatomical variations in retinorecipient brain areas in Arvicanthis niloticus and Rattus norvegicus: implications for the circadian and masking systems
Published in Chronobiology International, 2019
Dorela D. Shuboni-Mulligan, Breyanna L. Cavanaugh, Anne Tonson, Erik M. Shapiro, Andrew J. Gall
Volume analysis for the high-resolution T2-weighted images was conducted using the Measure tool in the ImageJ Program (NIH, Bethesda, MD). Three components of the visual system were clearly visible with MRI: SC, lateral geniculate nucleus (LGN), Habenula (EPI), and optic tract (opt). Two non-visual areas were also outlined as controls, the cortex (CTX) and hippocampus (HPC). The whole brain was then outlined to correct for total volume differences between the two species. A percentage was calculated by dividing the volume of each area by the whole brain volume and then multiplying by 100. Prior to statistical analysis, the percentage data were arcsine transformed. The 3D MRI were used to create 3D volume rendering of the regions of interest using 3D Slicer 4.8 (https://www.slicer.org/; Fedorov et al. 2012).
Multidisciplinary speech and language therapy approach in a child with multiple disabilities including blindness due to retinopathy of prematurity: a case study with a one year follow-up
Published in Logopedics Phoniatrics Vocology, 2023
Slavica Maksimović, Nina Stanojević, Saška Fatić, Silvana Punišić, Tatjana Adamović, Nenad Petrović, Vanja Nenadović
This paper describes a case of a child with multiple disabilities and blindness due to ROP. The main characteristics of the development of a child with blindness due to ROP are neurodevelopmental disorders and sensory processing impairment [15]. In our case, the problem was much greater, given that the child could not walk. Walking was hindered by visual deficits. The visual system plays an important role in providing information about where the body is in space, how fast it is moving, and what the possible obstacles are. It also participates in maintaining balance by sending vestibular information about the space in which the body is moving [68]. It was known that the child had no neurological or muscle impairment that would affect his walking ability; thus, it was a result of sensory processing difficulties and vision impairment. The perception of oneself, others, and space was based only on tactile and auditory senses, which were also impaired due to sensory processing difficulties. The basic goals of the treatment were to develop conditions for an optimal field of acceptance, modulation, and internal organization of external stimuli in order to create and modify adaptive mechanisms, trust (confidence), behavior, and development of speech and language.