The Neuroscience Approach

LEARNING OBJECTIVES

• How do the basic developmental forces benefit from the neuroscience approach?

• What is the major focus of the neuropsychological approach to neuroscience?

• Describe the difference between the correlational approach and the activation imaging approach to studying neuroscience.

• What is the difference between MRI and fMRI scanning?

t age 70, Margaret was diagnosed as having a tumor in her right motor cortex. She was treated with radiation therapy. Surgery could have left her paralyzed on the left side. With the aid of image — guided surgery, the tumor was found to be more accurately located in the front of the motor cortex. The tumor was removed and Margaret recovered comfortably.

An advanced technology involving a magnetic resonance imaging (MRI) scan was conducted on Margaret. This allowed areas of the brain associ­ated with specific functions to be identified and the level of activity in these areas to be monitored. The scan produced an image showing the anatomi­cal location of interest and the degree to which it was activated. In this case it was used to show more accurately the outline of a tumor and the critical areas of the cerebral cortex, especially those areas involved in controlling movement, sensation, speech, or vision. In addition to the clinical impli­cations of MRI scanning, we are interested in how such tools advance our understanding of how the brain changes as we grow older. Do the changes reflect decline, stability, or perhaps improvement and compensation? Is there plasticity in the aging brain? These are important questions that research­ers in the field of contemporary neuroscience and aging are exploring.

The 21st century has been described as the century of the brain. This is partly a function of numerous recent technological advances, such as the development of magnetic resonance imaging (MRI) that was used in Margaret’s surgery. This procedure and others have facilitated the study
of brain structure and functions using nonin­vasive methods. Because of these advances we can now more systematically examine the links between brain function and behavior in living beings. Of particular importance to the graying of America, neuroscientific approaches are being widely applied to research questions that deal with both cognitive and social-emotional aging. Although the greater part of neuroscience and aging research has focused on cognitive function­ing alone in older adults, recently researchers have used these techniques to investigate processing preferences for emotional compared to neutral information in older adults (see Mather, Canli, English et al., 2004). Similarly, research in the emerging field of social cognitive neuroscience has shown associations between brain structures and a variety of social cognitive tasks such as per­son perception, stereotypes, and theory of mind (Amodio & Frith, 2006; Ochsner & Lieberman,

2001) . One of the challenges for adult develop­ment theories will be to incorporate these models and techniques into our conceptual understanding of the aging process. We will introduce the neuro­science approach in this chapter and refer back to this approach when we tackle the specific areas of cognition, social cognition, and emotion.

A neuroscientific approach to the study of aging has specific advantages. For example, one par­ticularly beneficial outcome of this approach to research is that the neuroscience approach has taken intervention research to new pinnacles. Interventions that are important in enhancing the quality of life of older adults can now be eval­uated not only by observing behavioral change but also at the neurological level (e. g., Colcombe, Erickson, Raz et al., 2003). In particular, the neu­roscience approach offers a new level of analysis to understanding cognitive and social-emotional functioning. For example, neuroscience research demonstrates that areas of the brain related to visual processing decline with age. This provides a neuro­biological link for behavioral studies that show decline in visual functioning in older age is linked to declines in cognitive performance (Baltes & Lindenberger, 1997).

Implications of the Developmental Forces

The neuroscience approach offers a new level of analysis relating to the life-span thread that runs throughout this book, that is, behavior and devel­opment are multiply determined. At the simplest level, age is not the best predictor of behavior. As we learned earlier, age is related to specific psycho­logical, social, and biological phenomena that are associated with age-related change. Behavior across the life span is determined by multiple forces, some of which are age-related, such as biological changes, differing opportunity structures in soci­ety, and changes in motivational orientations and emotional functioning. From the perspective of neuroscience and aging, researchers now acknowl­edge that cognitive, social, and emotional change in older adulthood is influenced at multiple levels of analysis including both structural changes in brain volume and density and functional changes of brain areas. We must consider these biological changes in concert with behavior levels of analy­sis, including performance on cognitive tasks and social variables such as the positive and negative effects of stereotyping on cognition. As indicated, more complete investigation of these multiple forces on development has become more tractable for the biological level of analysis as new technolo­gies and research methods, such as brain imaging, have evolved.

Advances in understanding the dynamic and interactive process of these levels of analysis will be best exemplified when we talk about plasticity of the brain later in this chapter. Instead of simply looking at changes at the behavioral level, we can more directly observe the influence of environmen­tal interventions on the structure and activation of the brain itself. This can have important impli­cations for our understanding of irreversible and reversible changes in the brain and the possibility for behavioral changes that can occur throughout the life span. We have more converging evidence on the degree to which social interventions, biologi­cal interventions, and psychological interventions influence positive change and negative change as we grow older.

Neuroscience Tools

Magnetic resonance imaging (MRI) is a nonin­vasive technique that employs a powerful magnet (the MRI scanner) and radio waves to produce images of the brain. Whereas an MRI focuses on the structure of the brain, functional magnetic resonance imaging (fMRI) focuses on the func­tion of the brain. The MRI scanner has the ability to monitor the blood flow to different regions of

the brain as the participants in a particular study respond to specific stimuli such as an image of a face, words, or sounds. The difference between the MRI and the fMRI is that the more conventional MRI provides static snapshots of specific brain structures, whereas the fMRI monitors activities in the brain that are time-locked to behavioral performance.

These techniques and others offer new oppor­tunities to test models of cognitive aging. Neu­roscience has become increasingly more relevant to cognitive aging research as the focus has expanded beyond studying pathologies of the aging brain, such as Alzheimer’s or Parkinson’s disease, toward investigating normal and healthy aging. In addi­tion, neuroscientific data are more informative for models of cognitive aging and usher in increased progress in the field by testing established theories using cutting-edge methods. Furthermore, exami­nation of the structure and function of the brain has become even more informative for cognitive aging research as the focus has shifted from describ­ing brain activation patterns toward explaining them. However, it is easy to be seduced by these novel and available methods of neuroscientific investigation. The field of neuroscience and aging must be careful to base empirical studies on a solid theoretical foundation. The field of cognitive aging is a good example of an area that has profited from major advances in neuroimaging techniques, which have revealed findings that enhance our understanding of normal and pathological aging, yet require theoretical explanations (see Cabeza, 2004; Hedden & Gabrieli, 2004; Kramer, Fabiani, & Colcombe, 2006).