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Cortical Visual Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Laboratory measures of manual responses sho increased latency, abnormal hand trajectories, increased variability of the end of the reach, a tendency to reach to one side as well as dissociations of distance and direction control (395–397). In optic ataxia, reaching is usually normal toward foveated objects but impaired for objects in peripheral vision, with a correlation between reaching errors and target eccentricity (398, 399). Also, reaching is characteristically worse when performed immediately to the target: a delay of a few seconds can improve both reaching accuracy (45, 400) and the ability to avoid obstacles during movement (401). This suggests that the parietal cortex may play a specific role in rapid visuomotor control, and that there are alternative routes using the ventral stream for calculating object location and guiding slow reaching movements. This is supported by observations that patients with visual agnosia have normal rapid reaching responses but are impaired if action is delayed for a few seconds (402). Additional studies in patients with unilateral optic ataxia show that the reaching errors occur in a gaze- or eye-centered map, rather than a body frame-of-reference (403–405).
Neurofeedback in Application to the ADHD Spectrum
Published in Hanno W. Kirk, Restoring the Brain, 2020
The right parietal cortex plays an important role in integrating information from our senses to build a coherent picture of the world around us. It is involved in visual-spatial processing, spatial and body awareness, orientation of the body in space, and motor coordination on the macro-scale. Impaired function of the right parietal cortex can lead to a lack of self-awareness and spatial awareness, and it can result in the inability of the subject to control body movement, leading to hyperactivity.
Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Certain areas are identified with specific brain functions. The pre-central gyrus is known as the motor cortex and is the origin of all voluntary movements. The post-central gyrus is known as the sensory cortex and receives and appreciates all general sensations. Other important areas include the auditory area, which receives impulses from the auditory nerve and is situated in the cortex of the temporal lobe immediately below the lateral sulcus; the visual area, situated in the cortex of the occipital lobe and receives impulses via the optic chiasm; and the motor speech area (Broca’s area), which initiates tongue movements and is situated in the cortex of the frontal lobe just above the anterior end of the lateral sulcus. The sensory speech area that interprets the written and spoken word is situated in the lower part of the parietal cortex.
Navigation ability in patients with acquired brain injury: A population-wide online study
Published in Neuropsychological Rehabilitation, 2022
M. N. A. van der Kuil, J. M. A. Visser-Meily, A. W. M. Evers, I. J. M. van der Ham
Location-based navigation impairments describe problems in remembering, processing and updating the locations of landmarks in an environment (Burgess, 2006). In order to understand the location of objects in an environment, one constructs a mental representation of space. Impairments occur in the construction of egocentric representations (understanding where objects are in relation to your own location) and allocentric representations (understanding the configuration of objects in the environment regardless of your own location) (Klatzky, 1998). The parietal cortex is the key neural correlate involved in processing egocentric references frames while the hippocampus, parahippocampal gyrus and thalamus are typically involved processing allocentric representations during navigation (Colombo et al., 2017; Johnson & Davis, 1998).
Spatial neglect treatment: The brain’s spatial-motor Aiming systems
Published in Neuropsychological Rehabilitation, 2022
A. M. Barrett, Kelly M. Goedert, Alexandre R. Carter, Amit Chaudhari
Finally, a true understanding of directional motor biases will require that we are able to consider several neurophysiological fundamental sources of asymmetry. Posterior parietal cortex is (a) involved in motor planning and (b) may support improved movement after rehabilitation in patients with spatial neglect (Mattingley et al., 1998). We also need to measure electrophysiologic, hemodynamic, and cellular activation parameters to test, for example, whether loss of competitive equilibrium between hemispheres (Kinsbourne, 1977), altered gradients of information flow in local circuits (Nakayama et al., 2016), changes in preferred directional tuning at the level of individual neurons, or the disruption of cholinergic, adrenergic and dopaminergic neurotransmission (Luvizutto et al., 2015) may be more likely to account for symptoms. These method may be fruitful to co-integrate with lesion-symptom studies (Karnath et al., 2018), once large groups of well-characterized spatial neglect patients with Aiming spatial neglect are available. Thus, researchers studying spatial neglect rehabilitation should consider (1) dividing patients by presence or absence of frontal/striatal injury, or frontal brain disconnection (2) examining pre/post neurophysiologic parameters such as motor or sensory evoked potentials, brain activation, and brain vascular dynamics (Boukrina et al., 2019).
The medial prefrontal cortex: a potential link between self-deception and affect
Published in International Journal of Neuroscience, 2021
Kelly A. Duran, Hannah O’Halloran, Heather Soder, Saeed Yasin, Rachel Kramer, Sydney Rosen, Janet Brenya, Katherine Chavarria, Liliia Savitska, Julian Paul Keenan
There is substantial evidence that the medial prefrontal cortex (MPFC) is involved in self-evaluation and self-monitoring [1–5]. The MPFC has also been associated with self-referential encoding [6, 7]. Self-reflection and mentalizing consistently elicit activity in the MPFC [1, 8], and the MPFC has been shown to be involved in determining of the self-relevance of a statement [9]. Certainly, the MPFC is not the only area implicated in self-evaluation. The orbitofrontal cortex, anterior cingulate cortex [1], right PFC (Keenan, Falk, & Gallup, 2002), and precuneus (PZ) [10] have also been implicated. In addition, the lateral prefrontal cortex, parietal cortex, occipital cortex, cerebellum and caudate are involved in successful retrieval of self-encoded words [7]. It has been found that those who suffer from frontotemporal dementia, of which the behavior variance is characterized by frontal lobe atrophy [11], display a general deficit in self-awareness and error monitoring (O’Keeffe et al., 2007), and overestimated positive qualities while minimizing negative ones [12]. All together, these findings suggest that the MPFC may influence affect through maintaining a positive self-image.