Lecture 1 - Neurobiological Influences on Behavior

Brain development is often considered to occur in the context of three specific areas..

the forebrain, midbrain, and hindbrain

The midbrain is an area of the brain that thought to be involved with…

secondary movement, hearing, and vision functions

The hindbrain houses structures that are involved in …

movement, sleep and arousal, and life sustaining processes

The forebrain is a complex area of the brain that is considered to be responsible for …

cognitive thinking processes, high level processing, vision, and hearing

Both cerebral hemispheres, the thalamus, and hypothalamus are housed in…

the forebrain

The prefrontal cortex

an area of the frontal lobe, is an area of the brain responsible for executive functioning, such as decision making, sensation-seeking, and impulse control

The amygdala

• an area of the brain often involved in emotional processing

• It is also a driving force behind behavior as it is part of the limbic system

The thalamus

• an area of the brain that acts as a relay station, receiving sensory information and sending it to appropriate processing centers of the brain

• stimuli that may be used in behavioral responses is first sent here to be sent to areas of the brain involved in behavioral responsiveness. 

The hypothalamus is involved in..

• emotional control and behaviors associated with motivation

• controls emotion through release of specific chemicals that can alter mood, such as increasing feelings of adrenaline

The nervous system, including the brain, consists of …

• cells called neurons which transmit sensory information, convey commands/controls to other parts of the body, and help to coordinate cognitive and subconscious processes

• connections between neurons and chemical signals transmitted between them shapes our thought processes, actions, and memory formations

Neurochemical signals in the brain are transmitted …

via an action potential; an electrical signal runs through the length of the neuron and coordinates the release of specific neurotransmitters that lead to differential effects throughout the body

Dopamine

• a neurotransmitter that is involved in the pleasure pathways of the brain

• often thought to associate rewards with behaviors

• produced largely in the substantia nigra pars compacta and ventral tegmental area of the brain and is released in the nucleus accumbens and prefrontal cortex

• chemical formula of this is very similar to that of cocaine, leading researchers to believe that cocaine stimulates reward centers of the brain, making it an addictive substance

• Behaviors and substances that can initiate the pleasure pathway can motivate continued engagement in those behaviors through positive reinforcement

Serotonin

• ia neurotransmitter believed to be associated with sleep onset, blood vessel constriction, and depression

• underproduction of this may be a contributing factor to the development of certain mental health disorders and diseases, such as depression

• (90%) production in the body is actually found in the gut microbiome establishing the importance of the enteric nervous system (or the gut-brain axis) in our understanding of behavior

Gamma-aminobutyric acid (GABA)

• a compound found to be related to feelings of calmness through an inhibitory effect in the brain

• It is possible that this is related to anxiety

• these receptors may be involved in motivation for heavy drinking and the development of alcohol addiction

Acetylcholine

• a neurotransmitter involved with muscle movements and hormone secretion in glands

• it is also involved in attention and cortex neuroplasticity

Neuroplasticity

• refers to a process by which the brain adapts and modifies neuronal connectivity

• As the brain develops, excess neurons are pruned (or eliminated) to increase the efficiency of the connections made and reduce errors in neuronal connectivity

  • this pruning aids in learning and other processes that may ultimately contribute to the development of specific behaviors

Plasticity may also refer to …

• the ability of the brain to adapt following injury, substance use/abuse, and behavioral changes over time

• Recent research has found that using substances, such as alcohol, restructures areas of the brain so that using these substances becomes more rewarding, while other behaviors become less rewarding

• Changes to the structure of the brain can impact behavior, and vice versa (Geng et al., 2021).

  • For example, Phinneas Gage in 1848 was struck by a rail rod through his prefrontal cortex. Following this injury, those around him noticed behavioral changes such that he was more aggressive than prior to the incident. While this is an extreme case, it demonstrates that changes to the structure of the brain can influence behaviors. 

Methods of Assessing the Brain’s Impacts on Behavior

• Functional magnetic resonance imaging (fMRI) is a method that allows researchers to see which areas of the brain are likely involved with different tasks/behaviors. This method evaluates blood flow and oxygenation to certain areas of the brain, indicating their activation during certain behaviors. 

• Positron emission tomography (PET) scans similarly provides researchers with spatial information about active structures of the brain. Scans are generated by bloodstream injections of a radioactive substance that emits positrons, allowing researchers to produce a color-coded image of activity. 

• Computed tomography (CT) scans were the first developed to provide researchers with a spatial analysis of the brain. These scans are created through compilation of two-dimensional cross-sectional images. This allows researchers to evaluate the scans as though they are viewing a three-dimensional image of the brain.   

• Electroencephalogram (EEG) is a form of temporal scanning which allows researchers to assess neuronal electrical activity between electrodes. However, a weakness of this method is that researchers are not able to assess what structures of the brain are active.

Neurobiology and Aggression 

• studies suggest that aggression may be an evolved trait to protect social status, pass genetic traits, and protect offspring.

• While human social interactions complicate evolutionary selected traits, there may be evolutionary pressures that preserve aggressive behaviors in the gene pool. 

• There have also been recent studies that have focused on the role of mono-amine oxidase A (MAOA) in the development of aggressive and violent behaviors. Specifically, low levels of MAOA has been shown to associate with increased propensity for aggression and antisocial behavior. However, low MAOA expression alone may not be sufficient for the development of aggression and antisocial behaviors; childhood maltreatment and early life adversity contribute to the relationship between MAOA expression and antisocial behavior. 

Neurobiology in the Criminal Legal System 

• Neuroscience has become increasingly important in our understanding of criminal behaviors, and has been reflected in practice in the criminal legal system. For example, legal precedent suggests that tumors contributing to erratic, enraged, or aggressive behavior are grounds to reduce a conviction from first-degree murder to second-degree murder.

• Despite advancements in our understanding of the neurobiology of behavior, concerns for premature integration of this information in the criminal legal system has been raised

• indicate that because of the complex nature of behavior and the possibility of misuse of neuroscientific information, neuroscience should be carefully integrated in the criminal legal system. 

biological structures and processes contribute to…

the development of human behaviors that we often observe in the criminal legal system. Understanding the human brain and nervous system can enhance our understanding behavioral development.

Which neurotransmitter imbalance is most commonly associated with increased impulsive aggression?

Decreased serotonin

How could understanding brain plasticity inform policies aimed at reducing recidivism?

By developing rehabilitation programs that focus on cognitive and emotional skill-building

Why is neuroimaging an important tool for understanding the function of the brain?

It offers a non-invasive method of studying the brain's structure and function

Which neuroimaging technique measures brain activity through changes in blood flow?

fMRI (Functional Magnetic Resonance Imaging)

True or False: Screening for traumatic brain injuries in incarcerated populations can help provide tailored treatment for related symptoms.

True