Introduction to Biopsychology

What is Biopsychology?

• Biopsychology is the scientific study of the influence of biology on behavior
• Focuses on how the brain, nervous system, hormones, and genetics affect psychological functions like learning, memory, emotion, and perception
• It is also referred to as behavioral neuroscience or psychobiology
• These terms emphasize a biological approach to understanding psychological processes

Origins of Biopsychology

• Biopsychology became a major field in the 20th century
• A key milestone was the publication of "The Organization of Behavior" (1949) by D. O. Hebb
• Hebb's theory connected brain activity to complex psychological functions, including memory, emotions, and perception
• His work integrated experiments, clinical studies, and observations, and supported the concept that behavior has roots in brain processes
• Biopsychology is a rapidly growing scientific discipline despite being relatively new

Biopsychology's Relationship to Other Neuroscience Disciplines

• Biopsychology plays a key role in neuroscience by focusing on how the nervous system controls behavior
• Biopsychologists contribute expertise in behavior and research methods
• Biopsychologists integrate knowledge from neuroscience fields to better understand their connection, since the nervous system's main function is to produce and regulate behavior

Relevant Neuroscience Disciplines

• Neuroanatomy studies the structure of the nervous system
• Neurochemistry studies the chemical bases of neural activity
• Neuroendocrinology studies the interactions between the nervous system and the endocrine system
• Neuropathology studies nervous system disorders
• Neuropharmacology studies the effects of drugs on neural activity
• Neurophysiology studies the functions and activities of the nervous system

The Visual System

• Light reflected from objects is the basis for sight
• Light can be thought of as photons or waves of energy
• Light is defined as electromagnetic energy waves between 380 and 760 nanometers

Properties of Light

• Wavelength
• Intensity

Pupil

• The irises regulate the amount of light reaching the retinas as light enters through the pupil
• The adjustment of pupil size, a compromise between sensitivity and acuity, changes in illumination
• High illumination constricts pupils
• Low illumination dilates pupils

Lens

• Located behind the pupil
• Near gaze: the lens refracts.
• Distant gaze: the lens is flattened.
• Accommodation is adjusting the configuration of the lenses to bring images into focus on the retina

Binocular Disparity and Eye Position

• Vertebrates have two eyes because they have two sides, creating the opportunity to perceive depth
• Binocular disparity is the difference in the positions of the same image on the two retinas
• Your visual system uses the degree of binocular disparity to construct a three-dimensional perception resulting from the two two-dimensional retinal images

Retina and Translation of Light

• After passing through the pupil and lens, light reaches the retina
• The retina then converts light to neural signals
• The signals are conducted toward the central nervous system
• The signals participate in processing

Composition of the Retina

• Composed of five types of neurons: receptors, horizontal cells, bipolar cells, amacrine cells, and retinal ganglion cells
• Retinal neurons communicate both chemically via synapses and electrically via gap junctions
• The retina is inside-out, causing two visual problems:
  • Incoming light is distorted by the retinal tissue
  • A gap must exist in the receptor layer for bundle of retinal ganglion cell axons to leave the eye

Fovea

• Minimizes visual problems
• It is the area of the retina that is specialized for high-acuity vision

Completion

• A solution is required for the second visual problem, the blind spot, created by the inside-out structure of the retina
• The visual system uses information provided by the receptors around the blind spot to fill in gaps in your retinal images

Surface Interpolation

• It is the process by which we perceive surfaces

Cone and Rod Vision

• There are types of receptors in the human retina
  • Cone-shaped receptors, cones
  • Rod-shaped receptors, rods

Duplexity Theory of Vision

• The theory that cones and rods mediate different kinds of vision

Spectral Sensitivity

• A graph of the relative brightness of lights of the same intensity presented at different wavelengths is the spectral sensitivity curve

Photopic and Scotopic Spectral Sensitivity

• Photopic spectral sensitivity of humans can be determined by having subjects judge the relative brightness of different wavelengths of light shone on the fovea
• Scotopic spectral sensitivity can be determined by asking subjects to judge the relative brightness of different wavelengths of light shone on the periphery of the retina at an intensity too low to activate the few peripheral cones located there

Purkinje Effect

• As light levels decrease, an eye's peak sensitivity to light shifts toward the blue-green end of the spectrum, causing reds to appear darker relative to other colors

Eye Movement

• Involuntary fixational eye movements consist of: tremor, drifts, and saccades

Visual Transduction

• Converting light to neural signals happens using visual receptors

Pathway From Retina to Primary Visual Cortex

• The most studied visual pathway is the retina-geniculate-striate pathway
• This conducts signals from each retina to the primary visual cortex, or striate cortex, via the lateral geniculate nuclei of the thalamus

Retinotopic Organization

• The retina-geniculate-striate system is retinotopic
• Each level of the system is organized like a map of the retina

M and P Channels

• Two parallel channels of communication flow through each lateral geniculate nucleus
• These are the parvocellular layers (P Layers) and magnocellular layers (M Layers)

Receptive Fields: Neurons of the Retina-Geniculate-Striate System

• The reaction of most neurons in the retina-geniculate-striate system depended on whether they were on-center cells or off-center cells
• The reaction would be "on" firing or "off" firing to respond to light in a particular part of the receptive field

Field Receptiveness

• Receptive fields of most primary visual cortex neurons fall into one of two classes: simple or complex
• Simple cells:
  • these are like lower layer IV neurons
  • they have receptive fields
  • these can be divided into antagonistic "on" and "off" regions
  • they are thus unresponsive to diffuse light
• Complex cells:
  • more numerous than simple cells
  • they have rectangular receptive fields
  • respond best to straight-line stimuli in a specific orientation
  • they are unresponsive to diffuse light

Organization of Primary Visual Cortex

• Organized into functional vertical columns
• The location of functional columns in the primary visual cortex is influenced by:
  • the location on the retina of the column's visual fields
  • by the dominant eye of the column
  • by the column's preferred straight-line angle
• As Hubel and Wiesel's studies progressed from retina, to thalamus, to lower layer IV of visual cortex, to simple cortical cells, to complex cortical cells, the "preferences" of the neurons became more complex

Seeing Color

• Three different kinds of color receptors in the Component Theory (Trichromatic Theory):
  • Each with a different spectral sensitivity The color of a particular stimulus is encoded by the ratio of activity in the three kinds of receptors
• The Opponent-Process Theory suggests there are two classes of cells in the visual system:
  • Two encode color and another encodes brightness
• Color constancy refers to the fact that the perceived color of an object is not a simple function of the wavelengths reflected by it
• The visual system calculates the reflectance of surfaces to perceive their colors:
  • This compares the light reflected by adjacent surfaces in at least three different wavelength bands
• Injury to some areas of cortex may abolish certain aspects of vision while leaving others unaffected based on the Where versus what theory of vision
• Akinetopsia is a deficiency in the ability to see movement progress in a normal smooth fashion

Classified Visual Cortex

• Primary visual cortex receives most of its input from the visual relay nuclei of the thalamus
• Secondary visual cortex receives input from the primary visual cortex
• Visual association cortex receives input from areas of the secondary visual cortex as well as from the secondary areas of other sensory systems

Streams of Visuals - Dorsal and Ventral

• Dorsal streams flow from the primary visual cortex to the dorsal prestriate cortex to the posterior parietal cortex
• Ventral streams flow from the primary visual cortex to the ventral prestriate cortex to the inferotemporal cortex

Mechanisms of Perception

• Features of Sensory System Organization: Hierarchical Organization
  • The hierarchical organization of sensory systems is apparent from a comparison of damage effects to various levels. The higher the damage level, the more specific and complex the deficit

Functional Segregation Sensory System Organisation

• Parallel processing and summary model of sensory system organization

Auditory System

• The function is the perception of sound

The Ear

• Sound waves travel down the auditory canal
• They cause the tympanic membrane to vibrate
• These vibrations are then transferred to the three ossicles, the small bones of the middle ear: the malleus, the incus, and the stapes
• The stapes's vibrations trigger vibrations in the oval window membrane which transfers the vibrations to the cochlea
• The cochlea is a long, coiled tube with an internal structure that is the auditory receptor organ, the organ of corti

From Ear to Auditory to Primary Auditory Cortex

• The sensory signals ascend in a hierarchy through the nuclei to areas of the association cortex in prefrontal and posterior parietal cortex

Somatosensory Agnosias

• Astereognosis: is the inability to recognize objects by touch
• Asomatognosia: the failure to recognize parts of one’s own body

Perception of Pain

• Pain is paradoxical
• An experience that seems in every respect to be so bad is in fact extremely important for our survival

Pain

• The lack of clear cortical representation
• The ability to descend pain control is due to the fact that this most compelling of all sensory experiences can be so effectively suppressed by cognitive and emotional factors

Chemical Senses: Smell and Taste

• Smell and taste are chemical senses
• Molecules of food excite both smell and taste receptors creating an integrated sensory impression termed flavor
• The main adaptive role of the chemical senses is the evaluation of potential foods in natural environments

Smell System

• It consists of the nose and the nasal cavities, which in their upper parts support the olfactory mucous membrane for the perception of smell acting as respiratory passages in the lower areas
• Taste involves the Gustatory System
  • It is responsible fo the perception of taste stimulated when a substance in the mouth reacts chemically with taste receptor cells which are located mainly on the lounge
• Broad tuning vs narrow tuning - The archaic five-primary component processing theory of taste implied there are a variety of receptor molecules and mechanisms

Selective Attention

• Attention that suggests your brain can block from conscious awareness all stimuli:
  • except those of a particular kind while unconsciously monitoring the blocked-out stimuli just in case something comes up that requires your attention
• Simultanagnosia: a difficulty in attending visually to more than one object at a time
• Attention can focus in two ways:
  • By internal cognitive processes (endogenous attention)
  • By external events (exogenous attention)
• Cocktail Party Phenomenon is an example of attention

The Sensory Motor System

• Motor Output is guided by Sensory Input
• Learning changes the nature and locus of Sensorimotor control
• Sensorimotor system is Hierarchically Organized
• Sensorimotor Association Cortex in major areas:
  • Plays an important part in integrating two kinds of information, directing behavior by providing spatial information, and in directing attention across the Posterior Cortex
• Dorsolateral Association for the Prefrontal
• Receives projections from the posterior parietal cortex and it sends projections to areas of secondary motor cortex, to primary motor cortex, and to the frontal eye field
• Secondary Motor Cortex has output from the primary motor cortex
• Primary Motor Cortex: Is the major point of convergence of cortical sensorimotor signals, and it is major point of departure of sensorimotor signals from the cerebral cortex
• The Cerebellum:
  • Receives descending motor signals from brain stem motor nuclei, responses and vestibular systems
• Sensorimotor spinal circuits motor circuits show considerable complexity
• Descending motor signals are controlled and voluntary movements

Spinal Musculature and Ganlia

• Basal ganglia group near the center of your brain
• They connect to allow different areas of your brain to work together
• The ascending scending motor patrols and help one more

Central Programs

• Sensorimotor programs are those that have a sensory
• central sensorimotor programs motor equivalence and motor practices

Phases of Neurodevelopment

• The zygote differentiates and its cells align to form structures during neurodevelopment
• Neural Proliferation does not occur at the same rate
• Neuron death leads to passive and active cells

Postnatal

• Potentials affect development

Adulthood

• Neurons death is Synaptic

Experience and periods versus sensitive periods

• The competitive nature and manipulations of early experience that have effects on ocular.
• Neuroplasticity is where the brain is developed
• This relates to the disorders:
• Autism
• Williams syndrome