Lecture 1- The Limbic System Flashcards
Define the limbic system
Describes the limbic lobe, together with closely associated subcortical nuclei including the amygdala, septum, hypothalamus, habenula, anterior thalamic nuclei, parts of basal ganglia
Divisions of limbic structures
Archicortex
Paleocortex
Neocortex
Archicortex
Dentate gyrus
Subiculum
Hippocampus proper
= Hippocampal formation
Hippocampal formation
Hippocampus
Fimbria
Dentate gyrus
Subiculum
Plays a decisive role
Paleocortex
Piriform cortex of anterior hippocampal gyrus
Neocortex
Cingulate gyrus
Parts of the limbic system (modern definition)
Cingulate cortex Amygdala Septal Nuclei Hippocampal formation Part of hypothalamus (mammillary bodies) Ant nuclei of dorsal thalamus Vent striatopallidal complex
Cortex components of limbic system
Cingulate gyrus Subcallosal gyrus Dentate gyrus Parahippocampal gyrus Hippocampal formation Hippocampus proper Subiculum
Nuclei of the limbic system
Amygdaloid body (nuclear complex)
Septal nuclei (nuclear complex)
Some thalamic nuclei
Some hypothalamic nuclei
Connections of limbic system
Alveus Cingulum Fimbria Fornix Mammillothalamic tract Mammillointerpeduncular tract Mammillotegmental tract Perforant pathway Septohippocampal tract Stria terminalis Stria medullaris thalami Ventral amygdalohypothalamic tract
Limbic lobe
Cingulate gyrus
- Hyppocampal formation
- – via fornix
- Amygdala
- – via stria terminalis or ventral amygdalofugal pathway
- Septum
- – via forebrain bundle
All to Hypothalamus
Neocortical input to the limbic system
Parieto-occipital association cortex
Frontal association cortex
Temporal association cortex
to the limbic system, to the hypothalamus
Papez circuit definition
Closed circuit which linked the hippocapus with the cingulate cortex, via the mammillary bodies and anterior thalamus
Papex circuit theory
Emotional expression is …
organised in the hippocampus
experienced in the cingulate gyrus
expressed via the mammillary bodies
Components of Papex circuit
Backward-projecting neurons Projection into the entorhinal cortex Projection into hippocampus Fornix Mammillothalamic tract Projections from anterior nucleus of thalamus to cingulate cortex
Papez circuit purpose
Hypothalamus is the site where hippocampal processes gain access to autonomic nervous system outflow that controls expression of emotional states
Involved in cognitive processes, mneumonic functions and spatial short-term memory, and behavioural expression or emotions
Factors in production of emotion
The reinforcement contingency
Intensity of the reinforcer
Environmental stimuli have a number of different reinforcement associations
Theories for function of emotion
Elicitation of autonomic and endocrine responses prepare body for action
Flexibility of behavioural response to reinforcement stimuli
Motivation
Communication
Social bonding
Cognitive elevations of events or memories
Storage of memories
Continued motivation and direction of behaviour
Triggering of memories stored in neocortex
The septal nuclei location
- Beneath rostrum of corpus collosum
- Dorsal to ant commisure
- Ant to columns of fornix
Septal nuclei groups
Dorsal (dorsal septal)
Lateral (lateral septal)
Medial (medial septal nuclei and nuclei of diagonal band of Broca)
Caudal (fimbrial and triangular septal nuclei)
Efferent connections of medial septal nuclei
Habenular (via stria medullaris)
Hypothalamus (preoptic, lateral and mammillary bodies)
Hippocampus (most parts, except CA1)
Afferent connections of medial septal nuclei
Hypothalamus (preoptic, lateral, anterior, ventromedial)
Most are GABAergic or cholinergic and form part of topographical organised basal forebrain cholinergic system
Efferent connections of lateral septal nuclear group
Medial septal nuclear group
Hypothalamus (area above mammillary bodies, lateral dorsomedial preoptic anterior)
Ventral tegmental area
Afferent connections of lateral septal nuclear group
Hippocampal formation (some from both sides of brain) Ventral tegmental area (dopamine) Locus coeruleus (noradrenaline) Amygdala
