Speech Lecture Notes

Speech      Message generation: o Areas involved: left superior frontal gyrus, left frontal operculum and rostral left temporal cortex. Message sense – word retrieval: o Areas involved: medial temporal lobe. o In degenerative diseases, there are reductions in the volume of the left temporal cortex, left inferior and lateral frontal areas, anterior cingulate and right inferior frontal and temporal areas. Message sense – verbal knowledge: o Areas involved: anterolateral and inferior temporal lobe. Message structure: o Areas involved: inferior frontal gyrus and insula. o Phonological encoding is likely to involve a distributed left peri-Sylvian network involving the left inferior frontal lobe, and anterior and posterior superior temporal areas. Motor programming: o Areas involved: insula, pars opercularis and its subcortical connections. o Early mutism has been associataed with atrophy involving the pars opercularis and its subcortical connections. Word finding in different aphasias  Deficits of single-word comprehension are characteristics of disordered verbal knowledge in senile dementia and are also common in acute lesions involving the anterior temporal lobe.  Fluent aphasia arising from acute damage involving the posterior superior temporal lobe tends to be associated with less severe impairment of single-word comprehension, and more prominent phonological errors and neologisms. Unilateral spatial neglect  Hemispatial neglect typically results from damage of the right inferior parietal lobule (Brodmann areas).  Patients deviate their head and eyes to the side of the lesion and frequently neglect objects in the contralateral visual space.  Neglect of self: o Occasionally, the body half is neglected as well (personal neglect). o Entails a lack of spontaneous movements of that half (motor neglect).  In terms of distance: o Occasionally, neglect concerns only objects in far space (extrapersonal neglect) or near objects (peripersonal neglect). o Elementary visual and somatosensory functions may be preserved, but if compromised, the hemineglect may be so  severe that patients do not recognise the opposite body side as their own (alien-hand syndrome). o In less servere, more restricted cases, patients will not attend to objects in the opposite field of view (e.g. they will not draw the opposite sides of the objects). Syndrome of contralesional neglect reflects a severe disruption in spatial attention and is caused by lesions which damage the dorsal parieto-frontal streams of sensory processing. o Patients with unilateral spatial neglect ignore details in the left visual field. o Patients behave as if sensory events within the left extrapersonal hemispace have lost their salience, especially when competing events are concurrently occurring on the right side. Heautoscopy  The phenomenon in which a person experiences seeing a second own-body in extracorporeal space.  Subjects often report self-identification with the second own-body and heautoscopy is often associated with the sensation of being in two places at the same time.  Associated with vestibular sensations and detachment from emotional and bodily processing from the physical body, suggesting links with depersonalisation disorder.  Proposed that it is a disorder of multisensory (in this case, visual, tactile and proprioceptive) integration of bodily signals and an additional disintegration of such cues with vestibular signals.  Lesions in the right temporoparietal junction can induce perceptions of body being externalised – patients with epileptic seizures in this location report an out-of-body experience.  Can also be induced by application of transcranial magnetic stimulation to the right temporoparietal junction. Conclusions  Localisation of certain cortical functions is lateralised to either the left or right cerebral cortices.  Language is lateralised to the left side.  Broca’s area is located within the pars opercularis and pars triangularis of the left inferior frontal gyrus – rostral = semenatic; caudal = phonological processing.         Wrenicke’s area is located in the left posterior superior temporal cortex and is associated with the auditory images of speech. The arcuate longitudinal fasciculus is the long fibre tract that connects posterior (Wernicke) and anterior (Broca) language areas. It is important to recognise that damage to any of these left cortical areas will cause aphasia, including problems with fluency, articulation, word-finding, repetition, and producing and comprehending complex grammatical structures, both orally and in writing. Few patients present with either a purely expressive (motor) or receptive (sensory) speech deficit. Unilateral spatial neglect occurs almost exclusively after right hemisphere lesions which damage the dorsal parieto-frontal streams of sensory processing. Patients with unilateral spatial neglect behave as if sensory events within the left extrapersonal hemispace have lost their salience, especially when competing events are concurrently occurring on the right side. The right temporoparietal junction (TPJ) includes areas in which multisensory integration occurs. Lesions in the right TPJ can induce perceptions of the body being externalised: patients with epileptic seizures in this location report an out-of-body experience.