BOOK CHAPTER 1: Cognitive Neuroscience: Definitions, Themes, and Approaches

Introduction

• Cognitive neuroscience is a relatively new discipline emerging from the convergence of neuroscience and cognitive science.
• It integrates the study of brain structure and function with the measurement of cognitive abilities and behavior.
• Cognitive neuroscience seeks to understand how the human brain works at all levels, from basic perceptual and motor processing to complex thoughts and emotions.
• It addresses questions such as memory formation, social understanding, and decision-making.
• Cognitive neuroscientists employ diverse tools, including monitoring single neurons, tracking metabolic changes in the brain, examining the effects of brain damage, and temporarily inactivating specific brain regions.
• It aims to develop new models of cognitive functions that integrate ideas from both neuroscience and cognitive science.

Cognition

• Cognition, derived from the Latin term for "knowing," encompasses the processes that enable humans and animals to perceive stimuli, extract information, retain it in memory, and generate goal-directed thoughts and actions.
• While cognition is sometimes equated with processing by the mind, the term "mind" is difficult to define, often referring to subjective, conscious experiences.
• Cognitive neuroscientists study information processing, including processes that occur without conscious awareness, such as rapid reactions or automatic background processes.
• The term "mind" is restricted to the subjective sense of self, while "cognition" or "cognitive functions" describes the specific information processing studied.

Natural Philosophy and Early Psychology

• The nature of cognition has long been a subject of philosophical inquiry, addressing questions of perception, mental content, and free will.
• Historically, philosophers relied on introspection and reasoning to understand mental life due to the lack of experimental methods.
• In the 19th century, psychologists began to develop models of mental processes through behavioral observation and experimental manipulation.
• Pioneers like Wilhelm Wundt, Hermann von Helmholtz, and William James maintained connections with neuroscience while focusing on mental life.
• Their experimental methods, such as psychophysical judgment and memorization, are still used today to quantify cognitive processes.

Behaviorism

• The early 20th century saw growing dissatisfaction with the lack of progress in studying mental processes, particularly language and reasoning.
• Experimental methods like introspection were deemed imprecise.
• Behaviorism emerged as a dominant approach, emphasizing controlled experiments that matched objective external stimuli to measurable behavior.
• Behaviorism rejected subjective work on mental functions as unscientific.
• Behaviorists like John Watson and B. F. Skinner examined how changes in stimulus presentation could shape behavior.
• Skinner's concept of "operant conditioning" demonstrated that rewards reinforce preceding behaviors, leading to interest in reinforcing or discouraging specific behaviors.
• Because learning processes were considered common across species, research focused on non-human animals, such as rats and pigeons.
• Behaviorism was applied to human problems, including education and addiction treatment.
• Behaviorism advanced the scientific understanding of behavior and grounded psychology in an objective experimental approach.
• However, its focus on rewards led to the neglect of other cognitive functions, with mental states dismissed as inappropriate for scientific study.
• The view that psychological concepts could only be discussed in terms of experimental manipulations was termed "operationism."
• Ignoring complex mental states simplified experiments but reduced the scope of psychology.

Cognitive Science

• The mid-20th century saw a revival of psychological research on cognitive functions, spurred by the advent of computational science.
• Information theory provided new insights into perception, memory, and motor performance.
• George Miller's study in the 1950s showed that people can represent only about 7 unique items at one time in immediate memory.
• Miller argued that memory actively recodes complex stimuli into smaller units for cognitive processing.
• Computers provided a new model for mental processes, including symbolic representations and hidden layers of meaning.
• The metaphor of "mind as computer" became prevalent in psychology.
• Researchers began to reject the simplicity of the behaviorist research agenda and explore more complex aspects of mental life.
• Psychologists challenged the behaviorist concept of operationism, arguing that psychological states exist independently of experiments.
• Noam Chomsky argued that behaviorism could not explain the structural and generative properties of language.
• Psychologists began to involve more human participants in their research and investigate high-level, conscious processes.
• Cognitive science unifies research on mental processes across various disciplines.
• It focuses on information processing associated with cognitive functions and includes research with human participants, studies in non-human animals, and computational simulation of cognitive functions.
• Cognitive scientists come from various disciplines, including cognitive psychology, social psychology, psychiatry, neurobiology, linguistics, and philosophy.
• They aim to characterize phenomena and behavior associated with cognitive functions and create cognitive models that describe underlying psychological processes.
• Cognitive models predict how sensory input leads to behavioral output but posit psychological processes and internal states based on factors extrinsic to a specific experiment.
• The psychological processes invoked in cognitive science models do not necessarily map onto specific physical processes in the brain.
• Elements of cognitive models are sometimes called psychological constructs, created to explain phenomena without reference to their ultimate causes in the brain.
• Progress in cognitive science has been driven by experimentation and refinement of psychological constructs.
• Developments in neuroscience hold promise for grounding psychological constructs in neurobiological processes.

Neuroscience

• Neuroscience studies the organization and function of nervous systems in humans and animals.
• Early knowledge of nervous system function came from clinical cases and holistic views of brain function.
• Physician-scientists made inferences about brain function despite lacking experimental methods.
• The Roman physician Galen recognized that brain damage could affect cognition.
• By the early 19th century, physicians became interested in the functional properties of the cerebral cortex.
• Damage to the cerebrum led to various effects, with some individuals showing selective deficits.
• Franz Joseph Gall hypothesized that differences in cognitive functions and personality traits were associated with different parts of the cerebral cortex.
• Gall's hypothesis led to phrenology, which mapped the skull to assign functions and traits to different parts of the cortex.
• Phrenology faded as measurements of the skull were found to have no relation to brain structure or function.
• Phrenology introduced the idea of localization of function, which posits that different parts of the brain contribute to different sorts of information processing.
• Rigorous experimental approaches to neuroscience began to flourish in the second half of the 19th century.
• Santiago Ramón y Cajal's identification of neurons as separate cells implied that cognitive processes are carried out by large populations of neurons.
• Work on the electrical properties of neurons showed that signals are transmitted along axons by action potentials.
• Researchers developed recording techniques to track changes in electrical signals and explore chemical substances used to stimulate cells.
• Neurotransmitters are released at synapses and bind to receptor molecules on target neurons, altering their membrane potential.
• Understanding how neurotransmitters contribute to brain function remains important for both basic and clinical neuroscience.
• Neuronal signaling processes require energy from oxygen and metabolites supplied by the vascular system.
• Measurements of increased energy consumption and blood flow in active brain regions provide the bases for imaging methods.
• By the early 20th century, neuroscientists possessed experimental techniques for addressing questions about functional localization.
• Studies by neurosurgeons like Wilder Penfield mapped the cerebral cortex by applying weak electrical currents to the exposed cortex.
• Electrical stimulation allowed Penfield to create a map of the somatosensory cortex.
• Cellular physiology studies revealed how single neurons change their firing rate in response to specific information.
• Clinical neuroscience has shown that neurological conditions and psychiatric disorders reflect specific cellular problems or neurotransmitter dysfunction.

Cognitive Neuroscience: The Neurobiological Approach to Cognition

• Cognitive neuroscience combines cognitive science and neuroscience.
• Cognitive neuroscientists must understand cognitive processes and relate them to underlying brain function.
• It involves measuring brain function and assessing cognition and behavior, then linking them together.
• Cognitive neuroscience aims to create neurobiologically grounded models of cognition.
• Models of perception and motor control have been transformed by findings from neuroscience.
• Evidence from neuroscience has shaped debates in the field, such as whether attention filters perceptual stimuli at initial stages or later.
• By recording brain activity during attention tasks, investigators found that attentional filters operate at both levels.
• Cognitive neuroscience models have practical applications, such as understanding individual differences in cognitive abilities.
• By linking individual differences in cognition to brain function, researchers understand the neural bases for typical and atypical cognition.
• Differences in cognitive abilities can link genes and behavior.
• Understanding how different brain systems interact to support particular functions can guide genomic analyses in health and disease states.
• Cognitive neuroscience seeks to create biologically grounded models of cognitive function, informing and constraining prior cognitive science models.

Methods: Convergence and Complementarity

• Cognitive neuroscience uses research techniques from cognitive science and neuroscience.
• It employs diverse paradigms, from simple controlled experiments to more naturalistic behavior.
• It applies various neuroscience methods to measure or manipulate physiological processes.
• Using multiple methods provides convergence and complementarity.

Convergence

• Convergence combines results from multiple experimental paradigms to illuminate a single theoretical concept.
• This approach helped shift psychology away from behaviorism.
• Demonstrating the existence of internal mental states requires convergence.
• Cognitive neuroscience also requires convergence across paradigms.
• Consistent results across a range of experimental tasks lead to stronger inferences.
• Convergence is facilitated by meta-analytic methods.

Complementarity

• Complementarity of research methods provides different sorts of information about brain function.
• Cognitive neuroscientists use methods that provide insight into different aspects of physiology, such as fMRI, EEG, PET, TMS, single-neuron recording, neurological disorders, lesion studies, and assessments of behavior.
• Techniques vary in the aspects of brain function they record, their sensitivity to rapid or slow changes, and whether they collect information from single neurons or the brain as a whole.
• Perturbation techniques alter brain function and can be used to evaluate the causal contribution of specific brain regions or systems.
• Results obtained from multiple techniques are more compelling than results from a single approach.
• Convergence and complementarity also apply across research topics.
• Commonalities in brain regions engaged by different tasks can spur investigation of common processes.
• Cognitive neuroscientists must develop facility with a variety of research methods.

Box 1A: Convergence through Meta-Analysis

• Meta-analysis techniques combine information across multiple studies to improve inferences about cognitive functions
• Meta-analyses improve the power and precision with which researchers can detect and specify conclusions.
• Meta-analyses increase the effective sample size for analyses, allowing the identification of effects that replicate across studies.
• Meta-analyses may be especially important for understanding the neural basis of complex cognitive functions that can be evoked within a wide range of contexts.
• Approaches include: qualitative meta-analysis, quantitative meta-analysis, and semantic/ontological meta-analysis.

Conclusions

• Cognitive neuroscience provides a rich opportunity for students, despite the complexity of human mental life and the need to understand different technical approaches.
• The book takes a student-centered approach, with fundamental background material and examples of recent developments.
• The sequence of cognitive functions progresses from basic perceptual and attentional processes to memory, emotions, executive processes, decision making, evolution, and development.
• There is ample coverage of research methods.
• The aim is to describe how cognitive neuroscience has extended the scientific scope of both cognitive psychology and neuroscience.
• The primary goal is to help students gain an appreciation of the intellectual and methodological principles of cognitive neuroscience.
• By understanding the approach of cognitive neuroscience and its conclusions, students will gain a deeper understanding of the cognitive capabilities that define human beings.

Summary

1. Cognitive science seeks to understand the information processing associated with functions like perception, memory, and decision making.
2. Neuroscience seeks to characterize the structure and function of the nervous system.
3. Cognitive neuroscience is a new discipline that applies research methods from neuroscience to the functions and behaviors studied by cognitive science.
4. Cognitive neuroscientists use diverse research methods and experimental paradigms to develop models of mental function and behavior.