The Frontal lobes - Mahidol University

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19/07/54 The extrapyramidal system can be affected in a number of ways, which are revealed in a range of extrapyramidal symptoms (EPS), also known as extrapyramidal side‐effects (EPSE), such as akinesia (inability to initiate movement) and akathisia (inability to remain motionless). Extrapyramidal symptoms (EPS) are various movement disorders such as acute dystonic reactions, pseudoparkinsonism, or akathisia suffered as a result of taking dopamine antagonists, usually antipsychotic (neuroleptic) drugs, which are often used to control psychosis. The Simpson‐Angus Scale (SAS) and the Barnes Akathisia Rating Scale (BARS) are used to measure extrapyramidal symptoms 16
19/07/54 The frontal eye fields (FEF) is a region located in the premotor cortex, which is part of the frontal cortex of the primate brain. Function The cortical area called frontal eye fields (FEF) plays an important role in the control of visual attention and eye movements. Electrical stimulation in the FEF elicits saccadic eye movements. The FEF have a topographic structure and represents saccade targets in retinotopic coordinates. The frontal eye field is reported to be activated during the initiation of eye movements, such as voluntary saccades and pursuit eye movements. There is also evidence that it plays a role in purely sensory processing and that it belongs to a “fast brain” system through a superior colliculus – medial dorsal nucleus –FEF ascending pathway.In humans, its earliest activations in regard to visual stimuli occur at 45 ms with activations related to changes in visual stimuli within 45–60 ms (these are comparable with response times in the primary visual cortex). This fast brain pathway also provides auditory input at even shorter times starting at 24 ms and being affected by auditory characteristics at 30–60 ms. The FEF constitutes together with the supplementary eye fields (SEF), the intraparietal sulcus (IPS) and the superior colliculus (SC) one of the most important brain areas involved in the generation and control of eye movements, particularly in the direction contralateral to the frontal eye fields' location. Brain: Frontal eye fields Frontal eye fields is roughly located between regions #4, #6, and #8 Brodmann area 8, or BA8, is part of the frontal cortex in the human brain. Situated just anterior to the premotor cortex (BA6), it includes the frontal eye fields (so‐named because they are believed to play an important role in the control of eye movements). Damage to this area, by stroke, trauma or infection, causes tonic deviation of the eyes towards the side of the injury. This finding occurs during the first few hours of an acute event such as cerebrovascular infarct (stroke) or hemorrhage (bleeding). Distinctive features (Brodmann‐1905): compared to Brodmann area 6‐ 1909, area 8 has a diffuse but clearly present internal granular layer (IV); sublayer 3b of the external pyramidal layer (III) has densely distributed medium sized pyramidal cells; the internal pyramidal layer (V) has larger ganglion cells densely distributed with some granule cells interspersed; the external granular layer (II) is denser and broader; cell layers are more distinct; the abundance of cells is somewhat greater. Other Functions The area is involved in the management of uncertainty. A functional magnetic resonance imaging study demonstrated that brodmann area 8 activation occurs when test subjects experience uncertainty, and that with increasing uncertainty there is increasing activation. An alternative interpretation is that this activation in frontal cortex encodes hope, a higher‐order expectation positively correlated with uncertainty. Brain: Brodmann area 8 Supplementary eye fields (SEF) are areas on the dorsal‐medial surface of frontal lobe of the primate brain that are involved in planning and control of saccadic eye movements. The SEF was first characterized by John Schlag and colleagues as an area where low intensity electrical stimulation can evoke saccades, similar to the more lateral frontal eye fields. More recently it was shown that SEF stimulation produces coordinated gaze movements of both the eyes and head. Neural recordings in the SEF show signals related to both vision and saccades somewhat like the frontal eye fields and superior colliculus, but currently most investigators think that the SEF has a special role in high level aspects of saccade control, like complex spatial transformations, learned transformations, and executive cognitive functions 17
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Page 33 and 34: 19/07/54 Frontal lobe and Executive
Page 35 and 36: 19/07/54 An interesting phenomenon
Page 37 and 38: 19/07/54 The Frontal Lobes The pref
Page 39 and 40: 19/07/54 Impairment of Abstract Rea
Page 41 and 42: 19/07/54 Impairment of Motor Functi
Page 43 and 44: 19/07/54 Confabulation and Reduplic
Page 45 and 46: 19/07/54 Schizophrenia • Schizoph
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