Table 2.

Behavioral effects observed in mice harboring mutations related to thyroid function or wildtype rats with thyroid hormone status manipulation.

Gene	Mutation	Manipulation	Effect on cognition	Task used	Neural effects	Effect on transcription	Citation
Deiodinase 2	Knockout	Euthyroid and hypothyroid (PTU)	N/A	N/A	Minimal	Abnormal regulation of negatively regulated genes	Morte et al. (2010)
MCT8	Knockout	Euthyroid and hypothyroid (PTU)	N/A	N/A	N/A	None	Morte et al. (2010)
TRα1	Resistance	N/A	Deficit	NOR	Decrease in neurogenesis	Repression	Venero et al. (2005)
TRα1	Knockout	N/A	No effect Deficit	CFC Extinction	Increase in neurogenesis	No longer regulated by TRα1	Guadano-Ferraz et al. (2003) and Kapoor et al. (2010)
TRα	Knockout	Hypothyroid (PTU)	Deficit	MWM	N/A	No longer regulated by TRα	Wilcoxon et al. (2007)
hyt/hyt	Hypothyroid	N/A	Deficit	MWM	N/A	Repression	Anthony et al. (1993)
TRβ	Resistance	N/A	N/A	N/A		Repression	Portella et al. (2010)
TRβ1	Resistance	N/A	Deficit	Operant	N/A	Repression	McDonald et al. (1998)
TRβ1	Knockout	N/A	None	MWM CFC	Minimal	No longer regulated by TRβ1	Forrest et al. (1996) and Leach et al. (2015)
Wildtype rat	None	Hypothyroid (thyroidectomy)	Deficit	WRAM	Deficits in LTP	Repression	Alzoubi et al. (2006) and Alzoubi et al. (2009)
Wildtype rat	None	Hyperthyroid (T3 or T4 administration)	Enhancement	CFC, MWM	Increased Reelin and cholinergic activity	Activation	Sui et al. (2006)
Wildtype rat	None	Subclinical hypothyroid (hemi-thyroidectomy)	Deficit	MWM	Increased ERK activity	Localized effects	Ge et al. (2012)

↓ = decrease, ↑ = increase, ↔ = no change, (n.d.) = not determined, fT3 = free T3, and fT4 = free T4.