Cross-Modal Effects of Olfactory Sense on Memory Recall

Memory and learning are aspects of the human conscience that have fascinated researchers for centuries. Over the course of our lives, we make constant use of these processes and are regularly adding, removing, or editing information. Uncovering these processes could potentially give rise to treatments that enhance one’s memory and learning ability and possibly even minimize side effects of neurodegenerative diseases such as Alzheimer’s. Furthermore, individuals with Korsakoff’s syndrome who have severe deficits in memory, lack impairment in olfactory memory, suggesting that there is a separate pathway between olfaction and memory (Woronczuk et al., 2001). The olfactory sense is connected to one’s memory by the direct connection to the central nervous system’s (CNS) limbic system – a system that’s associated with memory and emotion – through the nerve fibers of the olfactory bulb (Buchanan et al., 2003). These nerve fibers extend posteriorly towards the hypothalamus, amygdala, and hippocampus. Both the hippocampus and amygdala are structures that are well known for being associated with both short and long-term memory. The hippocampus has also been determined to have olfactory functions. Synapses between neurons from the olfactory sensory tract and neurons of the hippocampus exist and have been documented by neuroscientists utilizing the aid of functional magnetic resonance imaging (fMRI) (deOlmos et al., 1978). Such synapses are an essential component of the communication between these neurons and overall retrieval of any information stored in the limbic system; which leads specialists to believe that this could be the beginning explanation for why organisms have olfactory memory. Employing the already established physiological connections between the sense of smell and memory, we postulated that if a particular odor could be coupled to a single memory, for example a picture, then it might be easier (faster) to recall that particular piece of memory if one is later exposed to the same scent that was previously associated with the stimulus (e.g. picture). Recent research has shown a relationship between verbal memory and olfactory memory. Most people tend to think that visual and verbal cues are easier to remember, but research shows that visual, verbal, and olfactory memories are all similar and carry the same strength in memory recollection (White et al., 1997). Furthermore, there is a phenomenon that states that olfactory memory triggers more emotional responses as well as increased detail in memory; this is known as the Proust Phenomenon (Toffolo et al., 2012). In addition, evidence exists in vertebrates, like chipmunks and bats, which have demonstrated utilization of odor cues to localize vital nutrients and recognize their offspring (Stevenson et al., 2012; Vander Wall 1991; McKracken 1993). This experiment is aimed to answer one question; do olfactory senses influence memory recall? Our hypothesis is that the if the olfactory sense can positively affect one’s ability to make memories, then one’s performance in a memory test that includes the connection with olfactory senses would improve.