This post is a part of our Bioethics in the News series
By Laura Cabrera, PhD
Should we be worried about the use of direct brain stimulation to improve memory? Well, it depends. If we think of people with treatment refractory memory conditions, or those situations where drugs are not helping the patient, such an approach might seem like the next sensible step. There is reason, however, to remain skeptical that this strategy should be used to improve the memories of people who function within a normal memory spectrum.
The quest to improve memory is hardly new. Throughout time people have engaged in ways to improve their memories, such as eating particular foods, employing mnemonic strategies, or taking certain drugs, but the quest does not end there. A recent New York Times article discussed findings from a direct brain stimulation study (Ezzyat et al., 2018) on the possibility of using brain stimulation to rescue functional networks and improve memory. In that study, 25 patients undergoing intracranial monitoring as part of clinical treatment for drug-resistant epilepsy were additionally recruited with the aim of assessing temporal cortex electrical stimulation on memory-related function.
The prospect of using brain stimulation to improve memory, initially introduced in the 1950s (Bickford et al., 1958) re-emerged in 2008 when a study using hypothalamic continuous deep brain stimulation (aka open-loop DBS) to treat a patient with morbid obesity revealed an increased recollection capacity in that same patient (Hamani et al., 2008). Subsequent studies have attempted to prove that direct brain stimulation is useful for memory improvement. However, the data on open-loop deep brain stimulation currently remains inconclusive.
The approach by Ezzyat and colleagues, wherein neural activity is monitored and decoded during a memory task, suggests an improvement over open-loop approaches. In this treatment modality stimulation is delivered in response to specific neural activity, detecting those times when the brain is unlikely to encode successfully and rescuing network activity to potentially improve overall performance.
In that study stimulation was triggered to respond exclusively to those patterns of neural activity associated with poor encoding, effectively rescuing episodes of poor memory and showing a 15% improvement in subsequent recall. Indeed, those results might sound promising, but this type of memory intervention raises a number of ethical issues.
In a very direct fashion memory is related to the core of who we are. It allows us to build an interpretation of ourselves and our environments, and in so doing gives us orientation in time as well as in our moral life. As surrealist Luis Bunuel put it, “Life without memory is no life at all … Our memory is our coherence, our reason, our feeling, even our action. Without it, we are nothing …” Equally, memory plays a crucial role in cognition, learning, and performance, and as such it is not a surprise that many people feel particularly drawn to memory improvement strategies. Yet there are salient, concerning issues when directly meddling with the human brain, including those risks associated with deep electrode insertion such as infection, hemorrhage, seizure and hardware complications. One might reasonably question whether a 15% memory improvement is worth such high stakes risks?
Another concern is the potential for undesirable – but as yet undetermined – side effects. Those uncertainties are why it seems unlikely that such an approach will be used in healthy individuals or for mild memory dysfunction cases. Still and yet, closed-loop deep brain stimulation has alternative utility. It can be used to improve understanding about the specific brain target most centrally related to certain memory functions, and then use that information to employ less invasive interventions, such as transcranial magnetic stimulation (TMS).
The sorts of studies engaged by Ezzyat’s team and others overlook the fact that memories are not just physically located within the cranial cavity. We have external technologies such as photographs, videos, and agendas to help us remember, and so one might reasonably ask if we really need invasive brain implants to achieve the same ends? The brain’s plasticity is equally overlooked, erroneously assuming that the same brain targets will bring equivalent outcomes for healthy individuals as well as for those with memory impairments. Moreover, the identified interventions improve memory encoding, but do not help with the many errors to which memory is perplexingly prone, such as misattribution, suggestibility, and bias. For healthy individuals, addressing those common memory errors could potentially be more helpful than improving encoding with brain stimulation.
In addition, certain types of memory enhancement could bring new perspectives on one’s life, and even affect the ability to understand the past and imagine the future. In fact if we truly were to remember everything we encounter in our lives we might well be overburdened with memories, unable to focus on current experiences and afflicted by persistent memories of those things that we deem unimportant.
Open-loop neural implants already bring a different configuration of human agency and moral responsibility. Closed-loop implants with their ability to both stimulate and continuously monitor neural patterns bring further issues for consideration, such as neurosecurity (e.g. brain hacking) and mental privacy. Improved connectivity of this type of implant further enables the potential for malicious interference by criminals. Concerns about mental privacy figure prominently in other neurotechnologies, which, similar to brain implants, have the ability to access neural data correlated with intentions, thoughts, and behaviors. This enhanced proximity encroaches on the core of who we are as individuals, providing access to mental life that in the past was accessible only to oneself.
Finally, the media hype in itself is problematic. The New York Times’ article mentioned that the 15% improvement observed in the Ezzayt study was a noticeable memory boost. This sort of inflated media coverage does a disservice to the good intentions and professional rigor of scientists and engineers, and misleads the reader to be either overly-optimistic or overly-worried about the reported developments.
With these many considerations in mind, it is clear that direct brain stimulation will replace neither pharmaceuticals nor less invasive memory improvement options anytime soon. Those who crave memory improvement through memory intervention technologies might best be mindful of the aforementioned ethical and social considerations.
Laura Cabrera, PhD, is an Assistant Professor in the Center for Ethics and Humanities in the Life Sciences and the Department of Translational Science & Molecular Medicine at Michigan State University.
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More Bioethics in the News from Dr. Cabrera: Can brain scans spot criminal intent?; Forgetting about fear: A neuroethics perspective
- Bickford RG, Mulder DW, Dodge HW, Svien HJ, Rome HP. 1958, Changes in memory function produced by electrical stimulation of the temporal lobe in man. Research Publications of the Association for Research in Nervous & Mental Disease, 36: 227-40. https://www.ncbi.nlm.nih.gov/pubmed/13527786
- Cabrera LY, Carter-Johnson J. 2018, It’s not my fault, my brain implant made me do it. The Conversation. https://theconversation.com/its-not-my-fault-my-brain-implant-made-me-do-it-91040
- Carey B. 2018, A brain implant improved memory, scientists report. The New York Times. https://nyti.ms/2Ek9q5R
- Ezzyat Y, Wanda PA, Levy DF et al. 2018, Closed-loop stimulation of temporal cortex rescues functional networks and improves memory. Nature Communications, 9: 365. https://www.nature.com/articles/s41467-017-02753-0
- Hamani C, McAndrews MP, Cohn M, Oh M, Zumsteg D, Shapiro CM, Wennberg RA, Lozano AM. 2008, Memory enhancement induced by hypothalamic/fornix deep brain stimulation. Annals of Neurology, 63(1): 119-23. https://www.ncbi.nlm.nih.gov/pubmed/18232017