Functional Subdivisions of the Orbito-Frontal Cortex
PSYC3209: Cognitive Neuroscience 2012
Q2. Discuss the neural mechanisms that underlie value-based decision making. Consider a situation where a choice needs to be made between hunting for food and seeking a warm shelter. To decide between these two fundamentally different rewards, the brain needs to calculate the values and costs associated with each option, consider different motivational, cognitive and contextual variables, construct a plan to obtain reward outcomes, and finally input these signals into a choice process. This essay aims to consider the function of the different brain areas involved in the above processes and how they may work together in a network to give rise to value-based decision making. Valuation-based learning and decision-making occur largely in the fronto-striatal network, involving four main regions, each responsible for a different function, as identified by Rushworth et al (2011): the ventromedial prefrontal cortex and adjacent medial orbitofrontal cortex (vmPFC/mOFC), lateral orbitofrontal cortex (lOFC), Anterior Lateral Prefrontal Cortex (aPFC) or Frontal Pole, and the Anterior Cingulate Cortex (ACC). Figure 1 depicts the above brain areas on a macaque brain, from which more precise research have been conducted in the field. While research in both human and macaque brains will be considered in this essay, neural imaging research in human often faces limitations such as the difficult-to-reach anatomical positions of these areas (many of them are located behind the eye lobes), and these brain regions being part of a “default network” (Raichle and Snyder, 2007), which means that they remain active at rest, and BOLD signals correspond to different degrees of deactivation compared to rest, rather than activation.
Figure 1. Frontal Brain Regions in the Macaque involved in valuation-based learning and decision-making.
The vmPFC/mOFC is the most well documented area in the four regions mentioned above. BOLD signals in this area has
Q2. Discuss the neural mechanisms that underlie value-based decision making. Consider a situation where a choice needs to be made between hunting for food and seeking a warm shelter. To decide between these two fundamentally different rewards, the brain needs to calculate the values and costs associated with each option, consider different motivational, cognitive and contextual variables, construct a plan to obtain reward outcomes, and finally input these signals into a choice process. This essay aims to consider the function of the different brain areas involved in the above processes and how they may work together in a network to give rise to value-based decision making. Valuation-based learning and decision-making occur largely in the fronto-striatal network, involving four main regions, each responsible for a different function, as identified by Rushworth et al (2011): the ventromedial prefrontal cortex and adjacent medial orbitofrontal cortex (vmPFC/mOFC), lateral orbitofrontal cortex (lOFC), Anterior Lateral Prefrontal Cortex (aPFC) or Frontal Pole, and the Anterior Cingulate Cortex (ACC). Figure 1 depicts the above brain areas on a macaque brain, from which more precise research have been conducted in the field. While research in both human and macaque brains will be considered in this essay, neural imaging research in human often faces limitations such as the difficult-to-reach anatomical positions of these areas (many of them are located behind the eye lobes), and these brain regions being part of a “default network” (Raichle and Snyder, 2007), which means that they remain active at rest, and BOLD signals correspond to different degrees of deactivation compared to rest, rather than activation.
Figure 1. Frontal Brain Regions in the Macaque involved in valuation-based learning and decision-making.
The vmPFC/mOFC is the most well documented area in the four regions mentioned above. BOLD signals in this area has