Speech rate as a sticky switch: a multiple lesion case analysis of mutism and hyperlalia.
Though it has long been known on the basis of clinical associations and serendipitous observation that speech rate is related to mood and psychomotor baseline, it is less known that speech rate is also related to libido and to immune function. We make the case for a bipolar phenomenon of "psychic tonus," encompassing all these dimensions. The elated, agitated, libidinal, immunofacilitated, and talkative pole is an "approach" disposition primarily activated by the normal left hemisphere-especially, though not exclusively, its frontal lobe. The dejected, lethargic, delibidinized, immunosuppressed, and mute pole is an "avoidance" disposition primarily activated by the normal right hemisphere-especially, though not exclusively, its frontal lobe. In support of this proposed model, we present new evidence, via meta-analysis of previously published single lesion case reports, of a highly significant association between right hemisphere lesions and non-aphasic hyperlalia, and between left hemisphere lesions and non-aphasic mutism.
Braun
Claude M J
CM
Centre de Neurosciences de la Cognition, Université du Québec à Montréal, CP 8888 Succ Centre-Ville, Montreal, Que., Canada H3C 3P8. braun.claude@uqam.ca
Dumont
Mathieu
M
Duval
Julie
J
Hamel-Hébert
Isabelle
I
D000339:Affect / Q000502:physiology; D001143:Arousal / Q000502:physiology*; D001714:Bipolar Disorder / Q000503:physiopathology; D001921:Brain / Q000503:physiopathology*; D001925:Brain Damage, Chronic / Q000503:physiopathology*; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D009155:Mutism / Q000503:physiopathology*; D012919:Social Behavior; D013068:Speech Production Measurement; D014705:Verbal Behavior / Q000502:physiology*