Tag Archives: brain

The Bidirectional Relationship Between the Brain and Behavior

Memory and Medicine

Cameron Hay is a cultural anthropologist who specializes in medical and psychological anthropology. Her research endeavors revolve around understanding, experiencing, and coping with illness and disease from the perspective of patients, family members, and health care providers. The goal of her research is to facilitate mutual understanding between patients, physicians, and public health experts in order to allow for enhanced communication, ultimately leading to better health outcomes. Specifically, she hones in on the social distribution of medical knowledge, health disparities, health literacy, empathetic communication, healer-patient communication, health care decision making, experiencing chronic illness, and psycho social stress and health. Hays is currently a professor and the chair of the department of Anthropology at Miami University in Oxford, Ohio. She also serves as the director of the Global Health Research Innovation Center and the coordinator of the Global Health Minor at Miami. Her secondary position is at the University of California in Los Angeles where she works as a researcher at the Center for Culture and Health at the Semel Institute for Neuroscience and Human Behavior.

Hays conducts ethnographic research in Lombok, Indonesia. Her case study titled, “Memory and Medicine”, that was featured in the book, “The Encultured Brain”, is a comparative study of the memory systems of Sasak healers and American physicians. This chapter is an analysis of contrasting medical practices of rural traditional Indonesian healers from the island of Lombok and urban biomedical doctors from California. Knowledge, memory, and memorization are the three key concepts that are employed in both healing systems. However, the extent to which each of these is deferentially used is crucial to understanding how medical information is socially and neurologically organized. Hays believes that different medical traditions utilize different types of memory systems which bolster the neurological memory processes in different ways. Three key arguments that shape her research are that memory and medicine co-evolve within local contexts, the co-evolution of these processes are not only evident in the analysis of medicine, and in order to understand her argument, we have to mend the gap between biological science, social sciences, and humanities.

Hays believes that the reason why neurological differences exist between these two types of healers is not because one practitioner is more intelligent than the other, but rather the neurological processes elicited in the memory encoding, organization and retrieval processes are intertwined with social, technological, and institutional traditions specific to that culture. In order to heal, the Sasak use jampi, or memorized formulas that are solely orally transmitted to selected individuals. Anxiety invoked during memorization is believed to enhance the memory encoding process. In America, formal training consisting of learning through evidence based scientifically published articles. In contrast to the Sasak, emotional anxiety is discouraged and viewed as a breech of clinical objectivity. Sasak medical tradition utilizes episodic memory which elicits the use of the hippocampal associative systems and is bolstered by emotional reactivity of the amygdala. American medical tradition utilizes a combination of episodic memory, semantic memory and procedural memory. The integration of medical knowledge is facilitated by the hippocampus but once schemas, or representative models are formed, schemas can be accessed independently of the hippocampus. Overall, Hay’s main argument is that any knowledge set is biocultural and influenced by differences in local assumptions, information distribution, learning and remembering processes, and the strengthening of certain neural pathways.

This article reminds me of several articles that I have read about fire walkers. Fire walkers are oftentimes able to recall specific details about their experience during this rite of passage.  This enhancement in memory is because the event was emotionally significant, causing their amygdala to become highly active, which assists with memory storage. Similarly, better memorization of a jambi formula may be due to the anxiety invoked when slapped on the arm. The ability to recall particular details about one’s fire walking practice or a specific jambi line is associated with the consolidation of episodic memories. This article also reminds me of the idea of synaptic pruning and the brains remarkable plasticity. For example, the brains of blind individuals show weakened neural associations within the visual cortex but enhanced neural associations in other brain regions such as those associated with sound.

I enjoyed reading this article but was also hoping she would have included articles in support of her suggestions. I wished there was an accompanying study depicting neurological evidence of a correlation between higher rates of neural activation in certain brain regions and specific health care providers. She mentions that the bridging of disciplines in order to enhance biocultural understanding is valuable, however, she fails to display this transdisciplinary and collaborative research essence in her own work. I also recognize that she may have other studies that do exactly what she proposes. What I did not fully see in her article is the applicability of her research. I understand why it is important that the brain is able to shift and differentially allocate resources to certain regions but other readers may wonder why it is important to know that some healers predominately use a specific type of memory. How is this research valuable and applicable to us? Most grant proposals and published articles require an explanation of the “bigger picture”. What I did not grasp as well was this “bigger picture” and exactly what her research contributes to the field of neuroanthropology.

Questions to Consider

  1. How can we benefit from this newly learned knowledge about the influence of cultural practice on neural pathways and the recollection of memories?
  2. What type of hypothetical research project could we propose to test the validity of the idea that health care traditions strengthen certain specific neural pathways?
  3. How can you use the “use it or lose it” phenomena to explain why certain neural pathways are augmented in healers cross-culturally?

Body, Brain, and Behavior: The Neuroanthropology of the Body Image

Charles D. Laughlin is currently a professor of religion at the University of Ottawa and is a professor emeritus of the Carleton University in Ontario, Canada where he previously taught anthropology and religion. Laughlin is interested in a theory that he and his friends, Eugene G. d’Aquili and John McManus, developed during the 1970s and 80s. The theory of biogenetic structuralism is a type of neuroanthropology that incorporates the brain, consciousness, and culture. Laughlin has devoted a large part of his career to collecting ethnographic data in Northeastern Uganda. Later, his interests in consciousness and the ways in which societies structure and interpret alternative states of consciousness led him to live in various Tibetan Buddhist monasteries in Nepal and India.

Lauglin’s article titled, “Body, Brain, and Behavior: The Neuroanthropology of the Body Image”, focuses on how an individual’s neurocognitive model of his or her body is comprised of a combination of internal and external sensory systems. He defines body image as, “a dynamic set of models within their cognized environment that integrates currently anticipated and remembered perceptions of their body, as well as all other habitually entrained neural networks producing affect, cognitions, and habitual motor patterns related to their body”. He proposes that the model of the body is already present within each individual upon birth but develops and takes shape through genetic predispositions and subsequent sociocultural influences. Prior to explaining his position, Lauglin provides the reader with a list of traits associated with the neuroanthropological theory of body image. He states that the body image is a construct of the nervous system, the body is transcendental relative to body image, and behavior controls perception so that the body perceived matches what is expected. This means that the ability to acknowledge one’s body is innate, developing prenatally, the actual physical body is much more complex than the nervous system’s model of it, and lastly, behavior provides a negative feedback loop so that individuals act in accordance with their desired body image.

Lauglin describes how the nervous system models the environment within the body by explaining the neural networks that are involved with body image development. He lists the different types of memory images and indicates that eidetic imagery, or images that occur vividly but are not perceived as real, may be used to change one’s body image. Lauglin also explains how the multiple representation model, or the belief that verbal and imaginal systems are distinct and independent modes of representation, is the most widely believed model, as opposed to collapsing both systems. He breaks down this model by explaining how the right hemisphere predominantly processes nonverbal imagery while the left hemisphere processes verbal symbolism. Lastly, Lauglin discusses how body image may be changed by using clinical methods that utilize ritualized visualizations and guided imagery may prove to be therapeutic and help change negative body image.

I enjoyed reading this article because body image is such a fascinating topic and a very salient topic as well, especially on a college campus. This article reminds me of the use of cognitive behavioral therapy (CBT) and dialectical behavioral therapy (DBT) to help alter maladaptive thought patterns. Lauglin’s article also relates to other articles I have read that discuss how facial and physical symmetry are one of the few characteristics that are seen as attractive and desired features of a prospective mate cross-culturally. I believe that from an evolutionary anthropology perspective, physical and facial symmetry are subconscious indicators of health and fertility. Symmetry may be an indicator of superb genes and people may subconsciously seek more symmetrical mates in order to reproduce with an individual who is more fertile and more likely to yield healthier offspring.

With respect to physical body size, the notion of attractiveness also varies from culture to culture. Some regions in the Middle East and Africa believe that larger body size indicates wealth since they can afford to eat and become large. Furthermore, larger body size may also be indicative of health and reproductive capacity since being undernourished may cause for fetal termination since it may not have enough nutrition to survive to birth. On the other hand, in America, it is believed that those who are thinner are wealthier since they have the means and resources to purchase higher quality foods or can afford to spend their money on gym memberships and their time exercising instead of working. Neither of these “indicators” may actually be true but this article led me to wonder about how body image disorders develop and why.

Questions to Consider

  1. What are some current ways in which body image disorders are currently being treated and how can we improve upon these methods according to Lauglin?
  2. Do you think that certain cultures have an increased incidence or prevalence of body image disorders compared to others? Ie. Do women in America have more rates of anorexia because thinness is portrayed in the media? Or do women in South Africa have more rates of binge eating disorder because being overweight is valued in that culture?
  3. Tying in Hay’s article, do you think that the neural pathways associated with negative body image are strengthened over time while positive body image pathways are weakened? Do you think this impacts one’s memory encoding, organization, and retrieval processes in any way?

The Evolving Human Brain

EVOLUTION AND THE BRAIN

It has long been appreciated that there is something about the human brain that makes it unique amongst other primates and mammals in general. Dr. Greg Downey  and Dr. Daniel Lende explore how and why the human brain has evolved the way that it has in Chapter 4 of The Encultured Brain: An Introduction to Neuroanthropology. The authors are well-qualified to provide an overview on this topic as both have a wealth of publications in this area, as well as being leaders in the development of the field of Neuroanthropology.

SIZE MATTERS

Blue Whale at The American Museum of Natural History

What makes a human brain unique? Is it simply the sheer size of it? Well, no. Anyone who has visited the American Museum of Natural History in New York City can clearly see that the enormous blue whale hanging from the ceiling has a brain much larger in size than that of a human’s. Perhaps the issue is not sheer size then, but the size relative to one’s own body. Unfortunately, we once again do not have a satisfactory explanation for human’s unique cognitive capabilities. While looking at relative size does work to explain the blue whale example (a blue whale’s brain only accounts for 0.01% of its body’s mass while a human brain accounts for 2%) we see other species that are an exception to this rule. For instance, a pocket mouse has a brain that comprises 10% of their body mass, much more than that of a human and yet we don’t see the unique functionality of a human brain expressed in a mouse.

Pocket Mouse at White Sands National Monument

However, when we turn instead to the encephalization quotient (i.e. the ratio of predicted brain mass to observed brain mass) we see that humans do stand out in this respect. In fact, humans exhibit an encephalization quotient that is between five to seven times higher than what is predicted for a mammal of our size. While greater encephalization is found across primates, humans are still an outlier and it appears this has been true for quite some time. Around two million years ago the genus Homo appears and with it we see a tripling in brain size in our ancestors as compared to other apes. However, it is not just the increase in size that is notable here–brain organization is a key component in better understanding our cognitive evolution.

STRUCTURE MATTERS

So, do humans simply have brains that have a ton of new structures that other primates don’t possess? This is once again an incorrect assumption. Rather than humans and primates differing in existing regions of the brain, our current evidence suggests that the differences are actually proportional which has fascinating implications for our evolutionary understanding of cognitive function. Instead of evolving new structures, it appears that humans have modified or repurposed existing structures so that certain brain regions have expanded at a different rate than others. This evolutionary trade-off has resulted in decreased development in areas like the human olfactory bulb, while structures like the cerebellum which is involved in frontal lobe functioning has shown great expansion.

Human Olfactory Bulb


CONNECTIONS MATTER

In addition to size and structure changing across evolutionary time, connections among regions of the brain have also seen significant changes.

In particular, we have seen an increase in the total number of neurons and with this, we see that larger brains tend to develop areas that are increasingly independent or modular which requires an increase in white connective matter. Understanding the brain’s connectivity is likely a key component of understanding human consciousness. Further, many researchers are now emphasizing the failure of previous metaphors such as the brain being “hard-wired” which does not capture the way in which brains are shaped through interactions and development (i.e. “wet-wired”).

NOT A BRAIN ALONE

To better understand how it is that experiences help shape the brain, Downey and Lende draw on the concept of niche construction which emphasizes the role that organisms play in shaping their own environment and subsequent selective pressures.

The authors argue that niche construction provides a place for cultural researchers within evolutionary studies–an interdisciplinary relationship that is too rarely created. This relationship is absolutely necessary since an understanding of human “intelligence” cannot be obtained by looking simply at the size and structure of the brain. Rather, we must also consider how our social relationships allow us to transfer and amass all of the components that we regard as forms of “intelligence” (e.g., technology, skills, information). Moreover, the authors emphasize how emotions, motivation, and perception are all factors that play into our social and cultural complexity and, thus, cognitive evolution.

MY THOUGHTS

This last section of the chapter was by far my favorite as I feel the authors made a convincing argument for the role of culture and social relationships in our understanding of human evolution. Additionally, I think that they do a great job of not allowing those who are skeptical or critical of previous evolutionary research to “throw the baby out with the bathwater.” I think their point is best summed up in the following quote:

Powerful, but overly simple, models of evolution that assume evolutionary traits will necessarily result in human universals need to give way, not to erase evolutionary explanations, but to provide richer accounts that incorporate data emerging from genetics, paleoanthropology, comparative neuroscience, and anthropology, including research on human diversity (p. 124).

EVOLUTION OF THE CEREBELLAR CORTEX: THE SELECTIVE EXPANSION OF PREFRONTAL-PROJECTING CEREBELLAR LOBULES

The lead author for this paper is Dr. Joshua Balsters whose research interests are in the area of social and emotional decision making. While not covered in the article, Dr. Balsters states that his specific interest is in Autism Spectrum Conditions (ASC) which he studies using a combination of fMRI, EEG, and computational modeling.

STUDY OVERVIEW

Capuchin Monkey

At the broadest level, the researchers are interested in whether the process of brain evolution is mosaic (i.e. evolutionary pressures act on individual neural structures) or concerted (i.e. evolution acts on interconnected parts of the brain that comprise whole functional systems). To test this, the researchers examine the cortico-cerebellar system in three different primate species: humans, chimpanzees, and capuchin monkeys.

METHODS

Chimpanzee

The study consisted of obtaining high-resolution MRI scans from 10 primates from each of the previously mentioned species (5 females and 5 males). All of the included primates had either reached sexual maturity or were close. The researchers were able to isolate the cerebellum and examine the lobules related to the primary motor cortex and the prefrontal cortex.

RESULTS

The data demonstrate that the lobules related to motor and prefrontal cortex occupy a greater proportion of the human cerebellum (83.87%) as compared to chimpanzees (67.1%) and capuchin monkeys (56.82%). Moreover, the results show that where there were increases in the prefrontal cortex, there were proportional decreases in the motor cortex. Since the volume of areas of the prefrontal cortex increased relative to cerebellar lobules connected to the motor cortex, these data suggest that these associated functional systems evolved together.

Cerebellum in Humans

DISCUSSION

This study provides support for the idea that brain systems evolve in a concerted fashion. The results from this study are important as they suggest a potential route to find clues regarding the evolutionary pressures that may have contributed to various expansions in the brain. Additionally, this research demonstrates how comparative MRI can be utilized to examine differences across primates.

MY THOUGHTS

I was able to somewhat follow the methodology of this study; however, I found myself both intrigued and somewhat intimidated by what I couldn’t grasp. This makes me wonder about some of the practical issues with interdisciplinary collaboration. I loved Downey and Lende’s description of how cultural researchers could and should be involved in evolutionary research, but there will likely be some limitations to this collaboration. In many ways, Balsters et al. (2009) is speaking a different language with words and acronyms that will have no meaning to someone who is not well-versed in the cognitive literature. Even simply grasping the hypothesis or overall finding for the study would likely be quite difficult for someone outside the field to grasp. Here is our challenge: if we were to reduce the complexity of the article, perhaps more researchers could understand the results; contrastly, researchers most likely to utilize this study will need a detailed report of the methodology and results in order to replicate or expand on this study. How do we find this balance? 

DISCUSSION QUESTIONS

  • How would our understanding of human brain evolution be different if we didn’t consider it in terms of niche construction?
  • What are some arguments against the idea that humans have “unusual cognitive abilities?”
  • In light of new ideas regarding “dual-inheritance,” what are some reasons why anthropologists might be uniquely qualified to examine human cognitive evolution?
  • How might we define “culture” in evolutionary terms?
  • With the full acknowledgement that there is very likely more than one explanation for human brain encephalization, what is your favorite theory for why humans evolved such large and complex brains?
  • How can we encourage interdisciplinary research when each field has their own “language”?

Gambling is not just a game

While reading the article “Compulsive features in behavioral addictions: the case of pathological gambling” written by Nadyel-Guebaly, I had several ideas for my research proposal, the biggest of which was to include gamblers as well as alcoholics.

Even though gambling is a behavioral addiction and alcoholism is a substance use disorder, they have many similarities.  I think it would be interesting to compare a behavioral addiction to a biologically based addiction because they are both addictions, just with different bases.  However, it might be hard to isolate gamblers from alcoholics because gambling often occurs with alcoholism.

One of the primary features of substance dependence is that “use is continued despite knowledge of having a persistent or recurrent physical or psychological problem.” Addicts compulsively use drugs without any thought of the consequences.  This is similar to pathological gamblers, who can have a hard time quitting gambling despite negative consequences such as losing all of their money.  These compulsive behaviors are associated with obsessive thoughts over the behaviors.  Both of these addictions are ego-syntonic, meaning they feel pleasure, gratification, or relief when they commit the act.  They cannot stop their addiction, because when they are in withdrawal they feel stress and anxiety which they want to get rid of.  The easiest way to not feel withdrawal symptoms is to not be in withdrawal anymore by taking the addictive substance or doing the addictive behavior.  Gamblers feels craving and withdrawal just like alcoholics do.

There are, according to Koob and Volkow, three stages of the addiction cycle: binge/intoxication, withdrawal/negative effect, preoccupation/anticipation (craving).  There are specific brain regions associated with each of these stages.  Binge/intoxication is associated with the ventral tegmental and ventral striatum.  Withdrawal/negative affect is associated with the extended amygdala.  Preoccupation/anticipation is associated with the orbitofrontal cortexdorsal striatum, prefrontal cortex, basolater amygdala, hippocampus, and insula.  It is this stage that I am particularly interested in.  I hypothesize that the preoccupation and anticipation of the addiction might be similar to having a mantra in meditation, which is related to increased pain tolerance.

For even more biology, there are different neurotransmitter systems that contribute to substance addiction and gambling.  Serotonin contributes to behavioral inhibition, and when it is suppressed the addicts feel a euphoric high.  Dopamine is related to learning, motivation, and salience of stimuli, including pleasureful rewards for enacting the addictive behavior.  Even though gambling is a behavioral addition and alcoholism is a substance use addiction, both of them effect the brain is a similar manner.

Evolving Brain Stuff, Y’all (part 2)

****Pictures coming soon***

I was especially excited to review “Evolution and the Brain ” from The Encultured Brain because evolution is something that interests me. I really like to see how evolutionary theory applies to different disciplines (can anybody say EvoS?). Theodosius Dobzhansky said “Nothing in biology makes sense except in the light of evolution.” I have found that this can apply to many different fields other than biology.

I have studied development in the context of evolution before, but never in a neurological context. This chapter really built onto my existing understanding of human evolution. As someone studying anthropology (I guess this is a neuroanthropology blog), I was especially excited to read about how the human brain and culture interact and how we can understand this interaction in an evolutionary context. Below is a quick summary of the chapter.

About the Authors

Greg Downey is Head of Department and Associate Professor of anthropology at Macquarie University. His interests include, but are not limited to, neuroanthropology, ethnomusicology, economic anthropology, and evolutionary theory. His main research focus is on skill acquisition from a neuroanthropological perspective.

Daniel H. Lende is an Associate Professor at the University of South Florida. His interests include neuroanthropology and biocultural medical anthropology. His research interests focus on substance and abuse, stress, cancer, PTSD, among others.

Together, Downey and Lende run the PLOS (Public Library of Science) blog site. The PLOS blog site is intended to facilitate discussion about science and medicine.

Size Matters

When we talk about how special human brains are, we typically first talk about size. Although size itself is not the only feature important when studying the brain, it is especially important to consider in an evolutionary context. It takes a lot of energy from high quality food sources to develop and maintain large brains. However, absolute size isn’t the determining factor of intelligence, and neither is relative brain size. Rather, the encephalization quotient of an animal best predicts brain and body size relationships. Humans are outliers, with a ~6X higher encephaliztion quotient for mammals our size.

Before our ancestors enjoyed an increase in brain size, they were distinguished by bipedalism. After this initial divergence, our ancestors’ brains tripled in size by two million years ago. Body size also increased, but not at the same rate. Another jump in brain size occurred about 500,000 years ago. Genetic research has revealed a great deal of similarity between humans and chimpanzees (our closest relatives) especially compared to our other primate relatives. Even the small differences in our genes account for huge phenotypic variation.

“Evo-devo” is a recently developed paradigm combining evolutionary theory and developmental biology. The idea that we can look at developmental processes to get an idea of how evolution has shaped us is not a new idea, but only recently has it been a widely accepted way of evaluating how evolution has shaped us.

Structure Matters

Comparative neuroscience is a great way to see how evolution has acted on the brain structure itself. By looking at human brains along with other primates we can see that evolution acts on existing structures, changing the function of a structure instead of creating a completely new structure. One way this is exhibited is by increasing the size of certain regions in proportion to others. There are often trade-offs when this happens; when one region increase another must decrease in order to remain metabolically stable. Humans are especially unique in our hemispheric specializations. This creates a streamlined process for quicker and more varied neural processing but also leaves us highly susceptible to injury (trade-off). Brain regions growing disproportionately is a demonstration of natural selection acting on this growth.

Connections Matter

The larger our brains get, the more neurons we possess, opening up more connections in neural pathways. Evolution acts, not only on the number of neurons in a region, but also on connections within and between regions. In humans, control of our larynx has been affected by a neocortical “invasion,” which is important for language. Other animals do not have these connections, and are therefore missing brain function vital to speech.

Not a Brain Alone

I think it is hard for people to grasp that intelligence is not shaped entirely within. Culture plays a big role in our learning and brain development. During the first three months after birth, there are many neurons in an infant’s brain that adults will not possess. During these three months, vital connections are made, and there is a pruning of neurons that go unused. It is during this time that a lot of cultural cues become ingrained in people. The social intelligence hypothesis places paramount importance on intelligence as a tool for cooperation. The focus is on the individual and how collaborative actions benefit the individual. In the cultural niche hypothesis, emphasis is on the interaction between multiple brain. Many human intelligence innovations could not be possible without the collaboration of multiple peoples’ brains. Regardless, sociality is a large contributing factor to human intelligence.