Topic 5: Cerebral Hemisphere Lobes, Functions, and Blood Supply

Frontal lobe

One of the major lobes of the cerebral hemisphere.

Parietal lobe

One of the major lobes of the cerebral hemisphere.

Temporal lobe

One of the major lobes of the cerebral hemisphere.

Occipital lobe

One of the major lobes of the cerebral hemisphere.

Insular cortex

Located deep to the lateral sulcus.

Limbic cortex

Functionally distinct cortex that includes the cingulate gyrus

Primary cortex

Initial processing of sensory or motor information.

Unimodal association cortex

Processes information related to a single modality (e.g.

Multimodal association cortex

Integrates information across multiple sensory modalities; involved in higher-level cognition

Primary Somatosensory Cortex

Located in the postcentral gyrus and receives input from the ventral posterior (VP) nucleus of the thalamus.

Primary Auditory Cortex

Located in the superior temporal gyrus and receives input from the medial geniculate nucleus (MGN) of the thalamus.

Primary Visual Cortex

Located in the calcarine sulcus in the medial occipital lobe and receives input from the lateral geniculate nucleus (LGN) of the thalamus.

Olfactory Cortices

Not processed in the neocortex; processed in paleocortical regions including the medial temporal lobe and orbital surface of the frontal lobes.

Vestibular Cortices

Located at the parieto-temporal junction and includes the Parietal-Insular Vestibular Cortex (PIVC).

Gustatory (Taste) Cortex

Located in the insular cortex

Unimodal Sensory Association Cortical Regions

Regions adjacent to the primary sensory cortices that perform further processing specific to that same sensory modality.

What Stream

A visual processing pathway from primary visual cortex to the inferior temporal lobe responsible for object recognition.

Where Stream

A visual processing pathway from primary visual cortex to the posterior parietal lobe responsible for spatial awareness and motion.

Primary Motor Cortex

Located in the precentral gyrus of the frontal lobe; executes voluntary motor movements.

Motor Association Cortex

Involved in planning and programming motor activity before it is executed by the primary motor cortex.

Prefrontal Cortex

Governs executive functions and higher-order cognition essential for adaptive and socially appropriate behavior.

Somatotopy

Organization of the primary motor cortex as a motor homunculus with larger areas for face and hands.

Corticospinal tract

Pathway through which the primary motor cortex sends axons down to influence lower motor neurons (LMNs).

Functions

Planning

Initiative

Motivation

Restraint

Judgment

Planning and Judgment

Anticipates and sequences complex behaviors; understands cause-effect relationships and long-term consequences.

Decision-Making

Weighs risk and reward and integrates emotional and sensory input.

Social Behavior

Regulates impulse control and socially appropriate conduct.

Abstract Reasoning & Mental Flexibility

Supports problem-solving and adaptation to new situations.

Cortical Connections

Strong reciprocal connections with parietal

Limbic System Connections

Interconnected with the amygdala and mediodorsal thalamic nucleus integrating emotion

Clinical Insight

Damage to the prefrontal cortex may result in poor impulse control

Chronic Pain and the Prefrontal Cortex

Chronic pain impacts psychological

Cortical Damage

Chronic pain leads to structural and functional damage in cortical regions not directly related to pain perception including the prefrontal cortex.

Mechanistic Links

Mechanistic links between pain

Chiropractic Implications

Study: Lelic D.

Spinal manipulation

Influences sensorimotor integration in the prefrontal cortex.

Chiropractic care

May modulate brain function and plasticity related to pain and motor control.

Broca's area

Located in the inferior frontal gyrus (left hemisphere) and responsible for expressive language.

Wernicke's area

Located in the posterior superior temporal gyrus (left hemisphere) and responsible for receptive language.

Aphasia

General term for language impairment.

Broca's aphasia

Difficulty producing language (non-fluent).

Wernicke's aphasia

Difficulty understanding language (fluent but nonsensical).

Anterior (Carotid) Circulation

Supplied by internal carotid arteries feeding the anterior and middle cerebral arteries.

Posterior (Vertebrobasilar) Circulation

Supplied by vertebral arteries forming the basilar artery leading to posterior cerebral arteries.

Anterior cerebral artery (ACA)

Supplies medial frontal and parietal lobes and superior motor and sensory cortices for the lower limb.

Middle cerebral artery (MCA)

Supplies lateral surface of frontal

Posterior cerebral artery (PCA)

Supplies occipital lobe (visual cortex) and inferior temporal lobe.

Thalamus

Acts as the gateway to the cerebral cortex serving as a relay station for sensory and motor information.

Relay Functions of Thalamus

Most sensory information except olfaction is relayed to the cortex via thalamic neurons.

Thalamic Nuclei

Organized into four main nuclear regions: Anterior

Internal medullary lamina

Y-shaped myelinated band that divides the thalamus into four main nuclear regions.

Integrative Functions of Thalamus

Filters and modulates information acting as a gatekeeper for cortical input.

Thalamic Nuclei Additional Regions

Includes Midline and Reticular nuclei.

Ventral posterolateral nucleus (VPL)

A thalamic nucleus involved in sensory processing.

Ventral posteromedial nucleus (VPM)

A thalamic nucleus involved in sensory processing.

Lateral geniculate nucleus (LG)

A thalamic nucleus involved in visual processing.

Medial geniculate nucleus (MG)

A thalamic nucleus involved in auditory processing.

Anterior nucleus

Part of the Papez circuit involved in memory and learning.

Dorsomedial (DM) nucleus

Involved in multimodal processing

VPL (lateral VP nucleus)

Relays somatosensory information from the body (trunk and limbs).

VPM (medial VP nucleus)

Relays somatosensory information from the face and taste.

VA & VL

Motor relay from basal ganglia and cerebellum to motor cortex.

Intralaminar nuclei

Involved in arousal and motor integration.

Reticular nucleus

Regulates activity of other thalamic nuclei.

Lateral geniculate (LGN)

Visual relay from retina to occipital cortex.

Medial geniculate (MGN)

Auditory relay from inferior colliculus to cortex.

Ventral anterior (VA)

Transmits motor signals from basal ganglia.

Ventral lateral (VL)

Transmits motor signals from cerebellum.

Ventral posterolateral (VPL)

Somatosensory relay for body.

Ventral posteromedial (VPM)

Somatosensory relay for face and taste.

Lateral dorsal (LD)

Part of thalamic nuclei.

Lateral posterior (LP)

Part of thalamic nuclei.

Pulvinar

Part of thalamic nuclei.

Diffuse-Projecting Thalamic Nuclei

Part of the Ascending Reticular Activating System (ARAS).

Consciousness

Maintained by diffuse projections from thalamic nuclei.

Damage to ARAS

Can result in coma.

Papez circuit

Involved in memory and learning.

Somatosensory Relay

VPL for body and VPM for face and taste.