Biopsychology: Parts of the Brain

Biopsychology Study Notes

Parts of the Brain

  • Date: Jan 29, PSYC110

Main Brain Divisions

  • Forebrain: Responsible for motivation, emotion, complex thought, and planning movement.

  • Midbrain: Involved in movement and dopamine production.

  • Hindbrain: Manages survival functions and movement.

  • Spinal Cord: Serves as a communication pathway between the body and the brain in both directions.

Hindbrain

  • Medulla:

    • Location: At the top of the spinal cord.

    • Function: Controls essential survival functions such as heart rate and breathing.

  • Pons:

    • Location: Above the medulla.

    • Function: Regulates sleep and arousal; coordinates movements on the left and right sides of the body.

  • Cerebellum:

    • Location: At the back of the brainstem.

    • Function: Essential for coordinated movement and balance.

Midbrain

  • Overview: Involved in the reflexive movement of the eyes and body.

  • Substantia Nigra:

    • Function: Initiates voluntary motor activity; critical for the production of dopamine.

    • Implication: Parkinson’s disease is associated with the death of substantia nigra cells, leading to a decrease in dopamine production.

Forebrain: Limbic System (Subcortical)

  • Thalamus:

    • Function: Acts as the gateway for almost all incoming sensory information before it reaches the cortex.

  • Hypothalamus:

    • Function: Regulates various bodily functions and influences basic motivated behaviors.

  • Hippocampus:

    • Function: Associated with the formation of memories.

  • Amygdala:

    • Function: Vital for processing the emotional significance of stimuli, particularly fear, and involved in memory processing during emotional arousal.

Forebrain: Cerebral Cortex

  • Overview: The outer layer of the forebrain, divided into two hemispheres:

    • Left Hemisphere

    • Right Hemisphere

  • Connection: Two hemispheres are connected by the Corpus Callosum, a massive bridge consisting of millions of axons.

Lobes of the Cerebral Cortex

  • Occipital Lobes:

    • Function: Important for vision.

    • Processing Center: Primary visual cortex (V1) characterized by a retinotopic map.

  • Parietal Lobes:

    • Function: Involved in touch and spatial relationships.

    • Processing Center: Primary somatosensory cortex helps in touch perception and space perception diagrammed as a "Homunculus."

  • Temporal Lobes:

    • Function: Important for processing auditory information and recognizing objects and faces.

    • Processing Centers:

    • Primary auditory cortex for hearing.

    • Fusiform face area (FFA) critical for face recognition.

  • Frontal Lobes:

    • Function: Key roles in movement, complex thought, and processes like rational thinking, attention, and social processing.

    • Processing Centers:

    • Prefrontal Cortex (PFC) for attention, self-control, and social interactions.

    • Primary motor cortex for controlling voluntary motor acts.

Pre-Frontal Cortex

  • Proportion: The prefrontal cortex occupies approximately 30 percent of the human brain.

  • Differentiation: The human brain differs from other animals primarily in the complexity and organization of its prefrontal neural circuits.

  • Lobotomy: A surgical procedure involving deliberate damage to the prefrontal cortex aimed at controlling behavior.

Primary Somatosensory

  • Parietal Lobes:

    • Location: Located in front of the occipital lobes and behind the frontal lobes.

    • Function: Involved in the sense of touch and in picturing the environment's spatial layout.

    • Processing Center: Primary somatosensory cortex.

Primary Sensory & Motor Homunculus

  • Representation of body parts in the brain concerning sensory and motor functions:

    • Notable body parts include:

    • Thumb, neck, face, eye, etc. for both sensory and motor processing.

  • The homuncular representation illustrates sensorimotor mapping, indicating the proportion of cortical area dedicated to different body parts.

Lateralized Function

  • Lateralization: A concept that suggests that specific cognitive functions (like language or spatial reasoning) are localized in one hemisphere of the brain rather than evenly distributed.

  • Hemineglect: A condition where an individual has difficulty attending to stimuli either on the opposite side of their body or space after brain damage, usually due to a stroke impacting the right hemisphere.

  • Broca’s Area:

    • Location: A small region in the left frontal lobe crucial for producing speech.

    • Expressive Aphasia: A condition where individuals know what they want to say but have difficulty forming words or sentences, often omitting smaller, connective words.

  • Wernicke’s Area:

    • Location: Located in the left temporal region, essential for language comprehension and processing.

    • Receptive Aphasia: A condition where individuals can produce grammatically correct sentences but may lack meaning and struggle to understand spoken or written language.

Split Brain Patients

  • Overview: In cases where the brain's hemispheres are surgically separated, the communication pathway between them is disrupted.

  • Finding: Experiments with split-brain patients showed when a participant is asked to name an object felt with the left hand, they can identify the object as known but fail to articulate it due to the lack of communication between hemispheres (Gazzaniga, 2002).

Conclusion: Understanding the structure and function of the various parts of the brain aids in appreciating the complexity of human behavior and thought processes.