Neuropsychiatry: brain injury, mental health–substance use
David B Cooper in Practice in Mental Health—Substance Use, 2018
Five major frontal-subcortical circuits have been described for this condition:8Dorsolateral-prefrontal circuit — executive function.Orbitofrontal circuit — social intelligence.Anterior cingulate circuit — motivation and emotional experience.Motor circuit — voluntary motor function.Frontal eye fields — eye movements.
Anatomy for neurotrauma
Hemanshu Prabhakar, Charu Mahajan, Indu Kapoor in Essentials of Anesthesia for Neurotrauma, 2018
Functional areas of the brain: Different areas of the cerebral cortex have specific functions, often described as Brodmann’s areas. The frontal lobe is involved in cognitive functions like reasoning and judgment, and in speech and language. The control of voluntary movement of skeletal muscles lies in the precentral gyrus (Brodmann’s area 4), also called the primary motor area or motor strip, immediately anterior to the central sulcus. It contains the cell bodies of the pyramidal tract. The area of the cortex representing a part of the body is proportional to the amount of motor control needed by that area, not just its size. Large areas of the cortex are, therefore, dedicated to the lips and hands (motor homunculus). The premotor area (Brodmann’s area 6), immediately anterior to the motor strip, is responsible for programming of motor movements. The frontal eye field in the middle frontal gyrus just anterior to the precentral gyrus (Brodmann’s area 8) controls the conjugate eye movements, visual reflexes, and pupillary constriction and dilatation. The motor commands for speech are programmed in the Broca’s area (Brodmann’s area 44,45), located in the inferior frontal gyrus of the dominant hemisphere. Biological intelligence, or executive functions such as reasoning and judgement, are controlled in the most anterior part of the frontal lobe (Brodmann’s area 9,10,11).
Giacomo Rizzolatti (b. 1937)
Andrew P. Wickens in Key Thinkers in Neuroscience, 2018
In 1971, Rizzolatti began his first experiments on monkeys. One of the brain regions that interested him were the frontal eye fields – an area located in the frontal cortex, just in front of the premotor cortex. This area was known to be involved in the shifting of gaze and the generation of eye movements, especially when tracking a moving object. However, in his attempt to record from neurons in this area, Rizzolatti also came across an adjacent region located in the premotor region itself, which only responded to visual stimuli close to the body or within the monkey’s reaching distance. This was an unexpected finding since this area of the brain was believed to be primarily involved in the planning and execution of motor action through its direct projections to the spinal cord. Rizzolatti also found that many of its neurons were bimodal, responding to both visual and tactile information, as occurs in hand-to-mouth movements. Clearly, the motor areas of the cortex still had secrets to give up, and in an attempt to elucidate their role, Rizzolatti began to map out its regions with new neuroanatomical techniques. According to Rizzolatti, this would show that the motor cortex does not consist of two main areas (e.g. primary and premotor areas) as classic accounts of the brain held but a mosaic of cortical areas with specific connections and functional properties. Rizzolatti would number these areas F1 to F5. Later, he would add two more regions (F6 and F7) to his classification of the premotor cortex.
Saccadic Eye Movements in Young-Onset Parkinson’s Disease - A BOLD fMRI Study
Published in Neuro-Ophthalmology, 2020
Anshul Srivastava, Ratna Sharma, Vinay Goyal, Shefali Chaudhary, Sanjay Kumar Sood, S. Senthil Kumaran
Functional neuroimaging has proved useful in exploring the saccadic circuitry and its intersection with cognitive circuitry.11 Furthermore, imaging studies have reported that saccadic tasks which involve inhibition of saccades versus simple visually guided saccades show different activation patterns. Greater blood-oxygen-level-dependent (BOLD) activity in the Frontal eye field (FEF) is attributed to saccadic initiation and reaction time.12 The supplementary eye field (SEF), a part of the medial frontal cortex is linked to saccadic tasks, which require performance monitoring.13 The frontal eye fields have been found to be activated more during response selection and saccadic goals.14 The frontal eye field is functionally distinct within itself where the lateral and medial FEF are involved in reflexive and volitional saccades respectively. The parietal eye field (PEF) and superior colliculus (SC) are also closely associated with reflexive saccades.12 The dorsolateral prefrontal cortex (DLPFC) is involved in the decision- making process by inhibiting undesirable reflexive saccades and therefore provides top down control of saccades.15 Error monitoring and saccadic inhibition are associated with anterior cingulate (ACC) activity as seen in antisaccades.12
Comparison of Functional Connectivity during Visual-Motor Illusion, Observation, and Motor Execution
Published in Journal of Motor Behavior, 2022
Katsuya Sakai, Junpei Tanabe, Keisuke Goto, Ken Kumai, Yumi Ikeda
All channels were referenced to 10–20 system landmarks (nasion, inion, right, and left preauricular points) and recorded using a 3 D digitizer (3 SPACE®, Fastrak®, Polhemus Co., Ltd, Colchester, VT, USA) to determine which brain regions corresponded to each channel positions. All channels then converted these coordinates into the locations of 40 channels based on an estimated Montreal Neurological Institute (MNI) space using NIRS-statistical parametric mapping (NIRS-SPM) (Tsuzuki et al., 2007; Tsuzuki & Dan, 2014). NIRS-SPM transforms the functional image to MNI space using probabilistic registration in reference to 3D digitized data of all channels and landmark positions using the 10–20 system (Tsuzuki & Dan, 2014; Yamazaki et al., 2020). This analysis demonstrated that the regions of interest (ROI) were the dorsolateral prefrontal cortex (DLPFC, channels 1–4), frontal eye field (channels 5–9), PMC (channels 10–22), M1 (channels 23–27), somatosensory area (Sa, channels 28–31), and Pa (channels 32–40).
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
Traumatic causes of focal neurologic deficits may include intraparenchymal hemorrhage, subdural hematoma, epidural hematoma, or internal carotid artery dissection. However, altered mentation would usually be observed in the presence of intra- or extra-axial hemorrhage that is large enough to cause focal deficits. Although an internal carotid artery dissection may lead to contralateral hemiplegia, it typically is associated with headache, neck pain, or Horner’s syndrome and tends not to disturb the frontal eye fields. In the absence of trauma, the differential diagnosis of the observed symptomatology may include ischemic stroke or seizure activity. Ischemic stroke and seizure activity can certainly present in a similar fashion; however, gaze preference should be a differentiating factor between these diagnoses. In the setting of ischemic stroke, inhibition of the frontal eye field would cause gaze deviation toward the lesion. Comparatively, seizure activity would stimulate the frontal eye field and cause gaze deviation away from the lesion.
Related Knowledge Centers
- Brodmann Area 8
- Eye Movement
- Middle Frontal Gyrus
- Paramedian Pontine Reticular Formation
- Retinotopy
- Saccade
- Smooth Pursuit
- Frontal Lobe
- Brain
- Precentral Gyrus