L4Physiological pt2

Introduction to Physiological Psychology

• Part two of the lecture series focusing on neurotransmitters and their role in neural communication.

Neurotransmitters

• Definition: Chemical messengers involved in neural communication, released by neurons in response to action potentials.

• Process of Release:

  • When a neuron fires, neurotransmitters are released into the synapse (space between two neurons).

  • They bind to receptor sites on the dendrites of the receiving neuron.

• Action Potential: If enough neurotransmitters bind, sodium gates open, altering the polarization of the neuron, potentially leading to its own firing.

• Reuptake Process:

  • If neurotransmitters are not utilized, they are reabsorbed by the presynaptic neuron for future use.

  • This process is called reuptake, pivotal for neurotransmitter regulation.

Serotonin

• Importance in Psychology: Linked to mood, emotion, sleep, appetite, and sexual desire.

• Connection to Depression:

  • Theories suggest serotonin deficits may contribute to depression.

  • Possible reasons include insufficient production of serotonin or lack of receptor availability despite normal production.

• SSRIs (Selective Serotonin Reuptake Inhibitors):

  • Medications like Prozac and Zoloft work by blocking the reuptake of serotonin, increasing its availability in the synapse.

Dopamine

• Role: Involved in reward, pleasure, voluntary movement.

• Connection to Psychological Disorders:

  • Schizophrenia: Linked to excessive dopamine in the brain; treated with dopamine antagonists which block receptors, reducing symptoms.

  • Parkinson's Disease: Connected to dopamine deficiency; treated with L-Dopa, a dopamine agonist that stimulates receptor sites and increases dopamine production.

• Addiction: Many substances affect dopamine levels, causing feelings of euphoria. This can lead to repeated use and addiction due to changes in the dopamine system.

Drug Impact on Dopamine System

• Cocaine: Inhibits dopamine reuptake, leading to increased dopamine in the synapse.

• Methamphetamine: Blocks reuptake and stimulates dopamine release, leading to higher surges of dopamine and extensive damage to the system over time.

Consequences of Drug Abuse

• Increased tolerance and need for higher doses to achieve the same effects.

• Damaged dopamine system leading to reduced pleasure from everyday activities (anhedonia), even after ceasing drug use.

• Risk of overdose as individuals seek to replicate earlier highs.

Brain Imaging Techniques

• Lesion Studies: Examine behavior changes following brain damage to identify functions related to specific brain regions.

• EEG (Electroencephalography): Measures overall brain activity and can identify different states of consciousness.

• MRI (Magnetic Resonance Imaging): Provides high-resolution images of brain structures to identify abnormalities like tumors and damage.

• fMRI (Functional MRI): Tracks brain activity by measuring changes in blood flow, allowing researchers to see active brain areas during tasks.

  • Useful in understanding emotional responses and specific cognitive functions.

Case Studies in Brain Psychology

• Phineas Gage: His accident revealed the concept of localization of function in the brain, demonstrating specific regions control specific abilities.

• H.M. (Henry Molaison): Surgery to treat seizures resulted in anterograde amnesia, highlighting the hippocampus's role in memory formation.

Advances in Neuroimaging and Understanding the Brain

• Brain imaging tech has illuminated specialized functions in the brain, such as areas responsible for processing faces, language, and auditory stimuli.

• Despite advancements, challenges remain:

  • Determining the causal relationships between brain regions and mental functions.

  • Understanding connectivity between regions and how that relates to various cognitive tasks.

Conclusion

• The exploration of the brain and its functions continues to be a pivotal area in psychology, merging biological understandings with psychological phenomena.

• The journey of understanding human experience through the lenses of neuroscience is an ongoing quest.