Similarly, in response to high-dose injections of corticosterone, eyeblink conditioning acquisition was facilitated in male Long-Evans rats, but there was no impact on acquisition in female rats ( Wentworth-Eidsaune, Hennessy, and Claflin 2016). In response to stress from a repeated tail shock, male rats acquired trace eyeblink conditioning (tEBC) faster than their female and unstressed male counterparts ( Shors et al. Sexually dimorphic effects of stress on learning have been shown on a variety of behavioral tasks.
2006 Elzinga and Roelofs 2005 Kirschbaum et al. 2005) or impair acquisition ( Diamond et al. Notably, stress exposure before learning can either enhance ( Domes et al. 1997 Magarinños and McEwen 1995 Sousa et al. 2005 Magariños, García Verdugo, and Mcewen 1997 Wiegert, Joëls, and Krugers 2007), a decrease in Brain Derived Nerve Growth Factor (NGF) ( Bath, Schilit, and Lee 2013 Lakshminarasimhan and Chattarji 2012 Smith and Cizza 1996), and a retraction of dendrites ( Gould et al. 2003), an increase in glutamate ( Karst et al. 2016) through several mechanisms such as an increase in neurodegeneration and decrease in neurogenesis ( McEwen 2000 Pham et al. As a result, chronic stress can cause impaired hippocampal-dependent function ( Moreira et al. Glucocorticoids alter many brain regions, including the hippocampus, which contains a large number of glucocorticoid receptors ( Moreira et al. Stress exposure can activate the hypothalamic-pituitary-adrenal (HPA) axis, leading to production of glucocorticoids, neurotransmitters and neuropeptides ( Lindau, Almkvist, and Mohammed 2016). Therefore, it is necessary to understand how the implementation of chronic recordings affects acquisition of learning and memory. In-vivo recording remains a critical tool for neuroscience research, especially as it expands with new technologies ( Hong and Lieber 2019). 2005), and time cells ( Manns, Howard, and Eichenbaum 2007). In fact, many fundamental neuroscience advances have come from extracellular recordings over the last half a century, including: place cells ( O’Keefe and Dostrovsky 1971), orientation-selective cells ( Hubel and Wiesel 1959), grid cells ( Hafting et al. Tandem mass tag mass spectrometry and western blot analysis suggest that significant alterations in the MAPK pathway, acute inflammation, and brain derived neurotrophic factor may underlie these observed sex- and surgery-dependent effects on learning.Įlectrophysiology has allowed neuroscientists to study a variety of phenomena including the activity of individual neurons and larger population encoding of groups of neurons have been studied with in vivo neuronal recording techniques ( Obien et al. These effects were not due to the weight of the drive alone, as there were no significant sex-differences in learning of animals that received “dummy drive” implants without tetrodes lowered into the brain. Microdrive implanted male mice acquired the associative learning paradigm faster than both intact and ovariectomized females.
While previous research showed intact female mice acquired trace eyeblink conditioning faster than male and ovariectomized females, implantation of chronic microdrive arrays showed sexually dimorphic effects on learning. Including both female and male mice in our associative learning experiments shed light on sex differences on the impact of chronic implantation of tetrodes on learning. Neuroscience techniques, including in vivo recording, have allowed for a great expansion in knowledge however, this technology may also affect the very phenomena researchers set out to investigate.
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