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Hypoglycemia reduces the blood‐oxygenation level dependent signal in primary auditory and visual cortex: A functional magnetic resonance imaging study
Author(s) -
Driesen Naomi R.,
Goldberg Philip A.,
Anderson Adam W.,
Tang Lin,
Flanagan Daniel E.,
Sherwin Robert S.,
Gore John C.
Publication year - 2006
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.21146
Subject(s) - hypoglycemia , functional magnetic resonance imaging , visual cortex , magnetic resonance imaging , auditory cortex , medicine , blood oxygen level dependent , diabetes mellitus , blood flow , audiology , anesthesia , psychology , neuroscience , endocrinology , radiology
Studies of the effects of hypoglycemia on the brain using neurocognitive testing have suggested that mainly complex functions subserved by secondary and tertiary cortex are affected by mild to moderate hypoglycemia and that intensively treated patients with Type I diabetes mellitus (T1DM) may have altered sensitivity to the central nervous system effects of hypoglycemia. Functional magnetic resonance imaging provides a sensitive, regionally‐specific probe of possible neurophysiologic changes related to hypoglycemia in the brain. Eleven intensively‐treated T1DM patients and 11 matched non‐diabetic controls took part in a 2‐day protocol in which functional magnetic resonance imaging (MRI) was used to measure changes in the patterns of brain activation produced by simple auditory and visual stimuli in different conditions. On one day, participants were euglycemic the entire time. On the other day, an initial 50‐min euglycemic period was followed by a 50‐min hypoglycemic period. Results indicated that hypoglycemia reduced the amplitude of the blood‐oxygenation level dependent response in primary auditory and visual cortex to simple auditory and visual stimuli. The latency and duration of the transient hemodynamic response function were not affected. Responses to hypoglycemia were similar in diabetic and non‐diabetic participants. These results suggest that mild to moderate hypoglycemia may alter the balance of blood flow and oxygen extraction when glucose levels are lowered. Intensively‐treated T1DM, with its attendant frequent hypoglycemic episodes, did not seem to alter hypoglycemic responses in primary visual and auditory cortex. © 2006 Wiley‐Liss, Inc.