Nerves

Definition: Biological psychology (physiological psychology) studies the connections between psychological functions and biological processes (both peripheral and central).
Key Interest: Examining how biological characteristics, including genetics, influence psychological functioning.
Overlap with Psychophysiology: Both fields measure physiological changes, but differ mainly in their approach and techniques used (invasive vs. non-invasive).
Historical Context: Psychophysiology has more established measurement methods which are also utilized in biological psychology.

Nerve Cells: The main functional units of the nervous system, involved in communication and processing of information.
Nervous System Composition:
- Central Nervous System (CNS): Comprises the brain and spinal cord.
- Peripheral Nervous System (PNS): Includes all other neurons and glial cells, often located in ganglia throughout the body.
Neuronal Communication:
- Neurons transmit information in one direction: from cell body to axon terminals.
- Afferent Neurons: Carry impulses to the CNS (input).
- Efferent Neurons: Carry impulses from the CNS to target organs (output).
- Associated functions: Sensory receptors provide information regarding environment (exteroception) and bodily state (proprioception, visceroception).
Motor Systems:
- Somatic Nervous System: Controls voluntary movements (striated muscles).
- Autonomic Nervous System (ANS): Governs involuntary functions, influencing cardiac muscle, smooth muscle, and glands.

ANS Components:
- Sympathetic Nervous System (SNS):
  - Prepares the body for activity (increased heart rate).
  - Connects CNS through spinal cord segments; utilizes norepinephrine as a primary neurotransmitter (except sweat glands).
- Parasympathetic Nervous System (PNS):
  - Promotes energy conservation (decreased heart rate).
  - Utilizes cholinergic synapses; postganglionic neurons release acetylcholine.
- Enteric Nervous System: A complex network of neurons regulating gastrointestinal functions.
Reciprocal Coupling: Activation of one division often correlates with the deactivation of another, but there are exceptions (e.g., coactivation).

Similarities: Both types of cells are elongated and excitable; respond to stimulus with electrical changes.
Neurotransmission:
- Neurons communicate via synapses; neurotransmitters are released in response to an action potential.
- Action Potential: A wave of depolarization along an axon, critical for nerve signal propagation.
Muscle Contraction: Initiated by nerve impulses; smooth muscle can contract without direct neural control due to intrinsic rhythms.

Measurement challenges: Requires sophisticated, often invasive techniques; signals can be weak.
Recording Considerations:
- Surface measurements affected by tissue depth, orientation of cells, and skin properties.
- Abrasion of the skin can enhance signal clarity.

Signal Acquisition: Use of electrodes placed on the skin to capture bioelectrical potentials.
Signal Adjustment: Filtering to remove noise and amplify the signal (e.g., low-pass, high-pass filters).
Display/Storage: Finalized signal is stored/processed for analysis.

Signal Instability: Recorded signals can vary due to external factors or internal physiological changes.
Baseline Activity:
- Tonic Activity: Refers to ongoing physiological signals impacting interpretations.
- Evoked Responses: Changes in physiological signals in response to stimuli.
Difference in Responses:
- Stimulus-response specificity and individual response stereotypy affect data interpretation.
- Directional fractionation in response patterns (e.g., varying heart rate and skin conductance under different conditions).

Safety Protocols: Laboratories must balance safety measures with experimental exploration.
Ethical Considerations: Participation must be voluntary and participants can opt out anytime; data handling requires consent.
Importance of awareness regarding psychological effects of stimuli, considering individual differences in responses.