Biomaterial Database

Startle amplitude and fear in an acoustic startle paradigm: lesions to the brachium of the inferior colliculus or the lateral tegmental tract. 2001

R N Leaton, and F H Brucato

Department of Psychological and Brain Sciences, Dartmouth College, Hanover, New Hampshire 03755, USA. leaton@dartmouth.edu

In 2 experiments, startle amplitude and startle stimulus-induced freezing (an index of fear) were measured in an acoustic startle response (ASR) paradigm in rats. Lesions to lateral tegmental tract (LTG), a pathway medial to brachium of the inferior colliculus (BIC), significantly decreased freezing and produced a persistent 5-fold increase in ASR amplitude compared with sham-operated controls. Lesions to BIC increased both ASR amplitude (2-fold) and freezing. Neither BIC nor LTG lesions affected startle amplitude when startle was elicited by a brief footshock stimulus. Characteristics of the lesion effects were tested with manipulations of interstimulus interval, stimulus intensity, and prepulse inhibition. The data suggest (a) an ascending pathway medial to BIC that carries the fear-inducing dimensions of an acoustic stimulus and (b) a descending pathway that provides tonic inhibition of the sensory input to the ASR circuitry.

UI	MeSH Term	Description	Entries
D007245	Inferior Colliculi	The posterior pair of the quadrigeminal bodies which contain centers for auditory function.	Colliculus, Inferior,Brachial Nucleus of the Inferior Colliculus,Caudal Colliculus,Colliculus Inferior,Inferior Colliculus,Posterior Colliculus,Colliculi, Inferior,Colliculus Inferiors,Colliculus, Caudal,Colliculus, Posterior,Inferior, Colliculus,Inferiors, Colliculus
D008297	Male		Males
D009415	Nerve Net	A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.	Neural Networks (Anatomic),Nerve Nets,Net, Nerve,Nets, Nerve,Network, Neural (Anatomic),Networks, Neural (Anatomic),Neural Network (Anatomic)
D009433	Neural Inhibition	The function of opposing or restraining the excitation of neurons or their target excitable cells.	Inhibition, Neural
D009434	Neural Pathways	Neural tracts connecting one part of the nervous system with another.	Neural Interconnections,Interconnection, Neural,Interconnections, Neural,Neural Interconnection,Neural Pathway,Pathway, Neural,Pathways, Neural
D001931	Brain Mapping	Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.	Brain Electrical Activity Mapping,Functional Cerebral Localization,Topographic Brain Mapping,Brain Mapping, Topographic,Functional Cerebral Localizations,Mapping, Brain,Mapping, Topographic Brain
D005239	Fear	The affective response to an actual current external danger which subsides with the elimination of the threatening condition.	Threat Cues,Threat Sensitivity,Cue, Threat,Fears,Sensitivity, Threat,Threat Cue,Threat Sensitivities
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001307	Auditory Perception	The process whereby auditory stimuli are selected, organized, and interpreted by the organism.	Auditory Processing,Perception, Auditory,Processing, Auditory
D013216	Reflex, Startle	A complex involuntary response to an unexpected strong stimulus. The reaction involves physical movement away from the stimulus, MUSCLE CONTRACTION and limb flexion, BLINKING, and changes in HEART RATE, BLOOD PRESSURE, and RESPIRATION.	Startle Reaction,Acoustic Startle Reflex,Reflex, Moro,Startle Response,Moro Reflex,Reaction, Startle,Reactions, Startle,Reflex, Acoustic Startle,Response, Startle,Responses, Startle,Startle Reactions,Startle Reflex,Startle Reflex, Acoustic,Startle Responses