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Delve into the intricate structures and functions of the frontal lobes, their evolution and vulnerabilities to various impairments such as trauma, neurodegenerative diseases, and psychiatric disorders. Explore how degenerative disorders like Pick's disease manifest in the frontotemporal region.
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Frontotemporal Dementia Thomas G. Bowers, Ph.D.
Frontal Lobes • Executive functions • Include attention, problem solving, hypothesis testing, social cognition and judgment • Relatively recent evolutionary development • Last structure to mature and develop (~25 years old)
Impact of Frontal Lesion • Gage’s behavior became socially very inappropriate • Displayed consistently poor social judgment
Basic Gross Anatomy • Motor, Premotor and Prefrontal regions • Many projections to premotor from other cortical regions • Extensive limbic projections to the premotor region
Frontal Organization • From anterior • 1. Prefrontal • 2. Premotor • 3. Motor
Frontal Organization • Prefrontal • Does not receive any primary sensory input except olfactory stimuli • Extensive projections from other cortical regions • Extensive projections from the limbic system • Reciprocating projections
Frontal Organization • Premotor • Broca’s Area • Critical convergence zone
Frontal Organization • Motor • Linked with the premotor cortex, sensory cortex, and the basal ganglia • Gives rise to pyramidal tacts that descend subcortically
Frontal Organization • Prefrontal – Limbic Links • Includes amygdala, hippocampus, thalamus, temporal lobe pole • Involves social processing as empathy, moral emotions, interpersonal judgment
Frontal Organization • Prefrontal – Subcortical Links • Thalamofrontal • Frontial-striatal • Difficulties here can include disinhibition, perserveration, loss of motivation, attentional disorders, hemispatial neglect
Vulnerable to Impairment • Traumatic brain injury • Axonal shearing, contusions, laceration, hemorrhage • Stroke • ACA, rostral aspects of MCA • Aneurysm • Neurodegenerative disease • Pick’s • Frontotemporal dementia
Vulnerable to Impairment • Psychiatric disorders • Hydroencephalus • Brain tumors • Orbitofrontal meningioma
Frontal Region is Vulnerable • Frontal pole and anterior horn of the temporal lobe in particular are sensitive to lesions • Coup injury • Contrecoup • Shearing injuries • Small petechial hemorrhage
Degenerative Disorders • Pick’s Disease • Atrophy has an affinity for the frontotemporal region • Development of Pick’s bodies • Frontotemporal dementia • Not frequent, but 10% of degenerative dementias