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Abstract

Abstract
Background:

Methodological discrepancies between studies have made it difficult to conclude whether heat exposure does or does not adversely affect cognitive function and under what specific environmental and physiological conditions these alterations appear.

Purpose:

To investigate what triggers cognitive and neuromuscular alterations during passive heat exposure.

Eight volunteers performed simple (OTS-4) and complex (OTS-6) cognitive tasks as well as neuromuscular testing (maximal isometric voluntary contractions of the thumb with electrical stimulation of the motor nerve and magnetic stimulation of the motor cortex). These tests were performed at the start (T1), after 1h30 (T2), 3h (T3) and 4h30 (T4) of exposure in both hot (HOT, WBGT = 38 ±1.4°C) and neutral (CON, WBGT =19 ±0.3°C) environments. Environmental temperatures were adjusted during the HOT session to induce target core temperatures (T) (T1 ∼37.3; T2 ∼37.8; T3 ∼38.3; T4 ∼38.8oC).

Results:

There were global effects of time (p < 0.014) and condition (p < 0.001), as well as the interaction (p < 0.001) for T. At T1 and T4 the OTS-6 performance was impaired in HOT compared to CON in response to the rapid increase in skin temperature (T) and to hyperthermia, respectively. In HOT, the increase in T limited force production capacity, possibly via alterations occurring upstream of the motor cortex (from T ∼37.8°C), but also via a decrement in motor cortical excitability (from T ∼38.3°C).

Discussion:

These alterations in cortex excitability failed to explain the cognitive alterations that can originate from an additional cognitive load imposed by temperature variations. Therefore, we suggest that the cognitive load imposed by the rapid increase in T or T caused performance decrements in complex cognitive task.

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/content/papers/10.5339/qfarf.2010.BMP29
2010-12-13
2020-09-26
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References

  1. N. Gaoua, J. Grantham, O. Girard, S. Racinais, Atypical Rett syndrome diagnosis by molecular testing, QFARF Proceedings, 2010, BMP29.
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http://instance.metastore.ingenta.com/content/papers/10.5339/qfarf.2010.BMP29
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